Analysis of real life 109E performance for CloD

[camber]

Many posters have stated their preference for CloD FMs to be historically accurate. Personally, I don't believe that it is possible. It is not historically accurate to clone a single aircraft across a whole theatre of battle. Additionally, "average" historical performance, even compiled with the least possible bias and most technical knowledge is still imprecise, and subjective decisions then need to be made (by the devs) about how to set up aircraft performance in the simulation.

But that said, I wanted to attempt to answer the question...if I had the opportunity to set CloD 109E performance as historically accurate as I could, what would I set?

Real life 109 performance is somewhat controversial..this thread is a good indication and summary:

http://forum.1cpublishing.eu/showthread.php?t=31450&page=19

The disagreement can be summarised as:

Position 1 (Fast guaranteed 109s): Messerchmitt guaranteed 500kmh on the deck and 572kmh max TAS for the 109E. The E1 prototype duplicates these figures theoretically once the actual flight tests are corrected for a measured engine deficiency of around 50PS.

Position 2 (Slow low 109s): Actual flight tests of production 109Es, both by Messerchmitt and by foreign governments on captured 109Es, indicate lower performance (primarily at low alt). Speeds are around 475kmh IAS/TAS on the deck and 560 kmh max TAS.

I support position 2, for reasons as follows.

Here is all the test data summarised. I am appending the data links at the end of the post. Most of this data is on "competing" websites (http://kurfurst.org and http://www.wwiiaircraftperformance.org). Most of it is on both, and it is exactly the same data..... however the interpretation is different. I will give kmh and mph figures, plus boost psi and ata.

http://i406.photobucket.com/albums/pp142/wjhawaii/109_performance.jpg

Postion 1 (Fast guaranteed 109s) requires explanations to why all the 109E actual flight tests show lower performance than "guaranteed". A good start is assigning lower significance to tests on captured aircraft, as these may not operating at maxiumum efficiency (for various reasons). However this makes no real difference to the data set, as the flight tests (besides the E1 prototype) are all similar. The only exception is the Russian captured aircraft which appears to be a (low performance) outlier at low altitude, and can perhaps be discarded from consideration.

For test 1 (E1 prototype) the converted (theoretical) data appears reasonable. The engine power deficiency was measured on the test stand and used to provide a theoretical correction to actual flight data.

For tests 2 and 3, the suggested reason for low performance is that the results are not corrected for nominal DB601A output, as was done for the E1 prototype (http://kurfurst.org/Performance_tests/109E_MP_E3_1792/WNr1792_E3_MP16feb39.html). However this begs the question, why were multiple production 109Es failing in tests to reach their guaranteed performance because of underperforming DB601s? This seems an unlikely scenario, and rather a bone of contention between Messerchmitt and Daimler Benz!

For test 5, the explanation for underperformance relates to the function of the DB601 supercharger. The hydraulic supercharger coupling of the 109 was intensely interesting to the British and there is a couple of very good, detailed explanations of it's operation in the period press:

www.wwiiaircraftperformance.org/me109/DB-601A-Flight-7Nov40.pdf
http://www.flightglobal.com/pdfarchive/view/1942/1942%20-%200516.html

Both the DB601 and Merlin had the same problem...a supercharger powerful enough to allow high altitude performance would give so much overboost (unthrottled) at sea level to cause predetonation and engine damage. The Brits developed a boost controller that automatically throttled the supercharger inlet to avoid overboost. The Germans worked out an elegant hydraulic supercharger coupling that spun the supercharger impeller slower at sea level and faster at height.

The DB601 hydraulic coupling had two oil pumps which pumped oil into the engine to impeller junction. One pump operated continuously but insufficiently for efficient coupling, allowing slippage of about 30%. As altitude rose, a barometric control increased the action of the secondary oil pump, reducing slippage to the minimum possible, about 2%. The corresponding impeller ratios were 7.2:1 at sea level rising to 10.2:1 at FTH.

The continuously varied supercharger output accounts for the curved nature of the 109 speed vs alt curves (e.g test 4) Unfortunately some tests seem to omit data points in favor of straight lines, making it hard to assess whether the curves are characteristic of the hydraulic coupling or not (e.g test 5)

The (fast guaranteed 109s) explanation for the test 5 underperformance is based on the hypothesis that the hydraulic supercharger setup can be altered in tests to act a two speed supercharger, and the Swiss were testing in high altitude configuration at all altitudes including at ground level. As a consequence the high altitude speed is about right but the sea level speed is low (http://kurfurst.org/Performance_tests/109E_SwissJ347/109E_J347.html)

This does not seem to be possible in light of the operation of the hydraulic coupling as explained in the references above. Manual operation of the variable oil pump (if possible) would have the following effects:

* If the variable oil pump is set to off, impeller slippage remains at 30%. Aircraft will perform normally at sea level, but boost will decay rapidly with altitude with consequent underperformance.
* If the variable oil pump is set to maximum, impeller slippage is held at 2%. The engine will be highly overboosted at sea level and will be unable to perform at all!

This also contradicts the idea that the test 1 (E1 prototype) performance is from a DB601 with hydraulic supercharger coupling manually manipulated to act as a two speed system. The data explicitly refers to a two speed system, so in the prototype it appears that the supercharger is an earlier direct and not hydraulic type.

The fact that the E1 prototype achieved higher sea level performance but similar maximum performance suggests that the hydraulic coupling had an efficiency penalty at low altitude as compared to a direct coupling. But the advantage of the hydraulic supercharger coupling in reducing pilot load in combat was probably considered an overriding factor.

I am not aware of other explanations of underperformance in the other actual 109E flight tests.

As to the Messerchmitt guaranteed performance, I am somewhat intrigued as it seems serial production 109s with hydraulic supercharger couplings did not meet it (at least at sea level). It would be nice to know the specific conditions (loading, boost etc) that went along with the guarantee, to assess what role it played.

So based on the above a reasonable (serial 109E with hydraulic supercharger) performance is based on the actual flight tests (minus the prototype):

475kmh IAS/TAS at SL 1.35ata 2400rpm
560 kmh TAS at 5000m 1.35ata 2400rpm top speed

1.35ata is 5 min combat limit. It is rather open to debate what effects sustained 1.35ata should have in the sim, what performance 1.45ata should give and whether it should work at all at height (historically it is a takeoff only boost after all).

camber

References for flight tests:

1 http://kurfurst.org/Performance_tests/109E_V15a/Geschw_109V15a.html
2 http://www.wwiiaircraftperformance.org/me109/Me-109E1-1791.jpg
3 http://kurfurst.org/Performance_tests/109E_MP_E3_1792/WNr1792_E3_MP16feb39.html
4 http://kurfurst.org/Performance_tests/109E_French_trials/french_109e_performanceT.html
5 http://kurfurst.org/Performance_tests/109E_SwissJ347/109E_J347.html
6 http://www.wwiiaircraftperformance.org/me109/Me-109E3-US.jpg
7 http://www.wwiiaircraftperformance.org/me109/Me-109E3-Russian.jpg

[IvanK]

Some more grist for the mill :)

The source is AVIA 6/9352 RAE Performance tests on the bF110 and BF109E
In the UK National Archives

http://i40.photobucket.com/albums/e215/zulu64/RAE109Espeeds.jpg

[41Sqn_Stormcrow]

I personally do not think that any plane should be modelled after some specifications. However seeing the dispersion of the test results one wonders why the 109 can only do 450 kph (pre-patch) at sea level and from what I read will do only 467 kph with the new patch.

Seems completely arbitrary to set it to 467.

To my understanding IvanK's graph shows a 109 with Rolls Royce radiators (because the original ones were damaged during the forced landing of the 109?) and which is well below in altitude speed than the French test.

[fruitbat]

pffft, everyone knows the 109E climbed better than an Electric Lightning, turned better than an Albatross, and had super cruise.

[Ernst]

The criticism on the Me flight tests is valid. Then the same criticism should be applied on R.A.E tests of the spitfires and hurricanes too, right? ;)

[von Brühl]

I personally do not think that any plane should be modelled after some specifications. However seeing the dispersion of the test results one wonders why the 109 can only do 450 kph (pre-patch) at sea level and from what I read will do only 467 kph with the new patch.

Seems completely arbitrary to set it to 467.

To my understanding IvanK's graph shows a 109 with Rolls Royce radiators (because the original ones were damaged during the forced landing of the 109?) and which is well below in altitude speed than the French test.


Strange, I can only get 430kph level flight after the patch, anyone else confirm 467? I didn't see the 109s speed in the patch release notes, so thought it hadn't been fixed yet.

354mp/h also seems to agree with the Basic Flight Manual, Military Intellegence, Identification of German Aircraft published in 1942 by the War Department March 11, 1942 (page 16). It lists the 109Fs at 380mp/h.

http://img209.imageshack.us/img209/7819/109specs.jpg (http://imageshack.us/photo/my-images/209/109specs.jpg/)

Uploaded with ImageShack.us (http://imageshack.us)

Even more reinforcement is the ranges, first I've seen comparative ranges in a time period specification. If it's top speed is truly 470kph, then 322mph in range would have to be diving, and it could hardly dive 540miles without starting in space!

[Kurfürst]

Some more grist for the mill :)

The source is AVIA 6/9352 RAE Performance tests on the bF110 and BF109E
In the UK National Archives

http://i40.photobucket.com/albums/e215/zulu64/RAE109Espeeds.jpg

IMHO that graph illustrates how hopeless is it sometimes to come up with the 'correct' performance figures. All of these tests were performed with the same 109E-3, WNr 1304 by various establishments in varying power and aerodynamic conditions, and they all differ wildly.

[robtek]

I really dont understand this discussion, any 109 not meeting the guaranteed values from Messerschmitt was rejected by the Luftwaffe to be refurbished by Messerschmitt.

Each and every plane had a acception flight to prove it delivered the guaranteed values.

If there should be a deviation from the guaranteed values programmed in game, this deviation must be valid for ALL planes in this sim.

[41Sqn_Stormcrow]

This just says that the 109 performance was quite certainly above the 500 kph minus 5% and would in no way exceed 500 kph plus 5%. But where should be the S/L speed be set for the 109 ingame?

The specification says NOTHING about average performance. The 500 kph is a fully theoretical value and was never meant to reflect real average performance.

I also highly doubt that the average 109 reached 500 kph and all tests indicate that it did not reach this value.

My guess is that the average speed at s/l was somewhere between 475 and 485 kph considering the flight tests.

If the average flight speed was 500 kph one should find flight tests showing individual 109s with speeds ABOVE 500 kph. I have never seen anything like that.

[robtek]

I've seen such a acceptance diagram from Meserschmitt 109's, but i don't know which series it was, anyway the general deviation was about 10 km/h below the guaranteed value, iirc. A few were above, the majority slightly below and five had to be refurbished because they've failed.
Found it: http://www.kurfurst.org/Performance_tests/109G_Erlatrials/Erla109G_13speedrun_scatter_web.jpg

[41Sqn_Stormcrow]

I've seen such a acceptance diagram from Meserschmitt 109's, but i don't know which series it was, anyway the general deviation was about 10 km/h below the guaranteed value, iirc. A few were above, the majority slightly below and five had to be refurbished because they've failed.
Found it: http://www.kurfurst.org/Performance_tests/109G_Erlatrials/Erla109G_13speedrun_scatter_web.jpg

That's been a 109G if I remember well (and the speeds as far as I can read them confirm that it is not a 109E). I have some doubts if the 10 kph can be transposed to an earlier model. I am not sure if the scattering could be transposed to the 109E. It would be great to find a similar graph for the E version but all presented tests of the E indicate that the performance was below 500 kph.

[Kodoss]

@Robtek: And it says Erla 109G_13speedrun...
DB 605A Steig- Kampfleistung...

Has nothing to do with any E-Series!

[TomcatViP]

What I don't understand is why ppl here simply don't have a more modest approach with plane perf and simply listen to what flight manual told us.

Is there any flight manual available that lies greatly abt the perf plane for any major country during WWII ? No

The variability is even accepted as beinh ard 5% for german plane wich were certainly the most hard pressed aero industry for all metals airplanes (with JN) during the war.

So why do we hev to rely on obscure test flights when we all know that foreign test of captured aircraft is always a difficult exercise ?

Are the 33000+ Me109 delivered just a gigantic scam shared by all the pilots that flew them ?

Enough is enough.

On one side we hve Spits fanatics that want to prove that actual flight manuals were wrong and perfs were better due to field made mod that nobody really heard abt etc..

ANd on the other side, the anti 500-kph mafia put on every thread test flight with less than average test result for the 109.

Messer had some problem with their deliverable, notably due to the innovative construction tech and higly tuned cellules and aerodyn. This is a well known fact and the german autorities put high pressure on him to fix this.

[ConjucturingMode=ON] That one low performing 109 was flight tested to prove that meaning in front of Messer's officials and low perfs duely recorded does not mean that Messer was allowed to sell 3000+ under performing E model... C'mon guys. Heads up for a while. WHat about that much talked SA ! [/ConjoncturingMode=OFF]

Just relax. Ok there is some test from Fr for example with planes that we know had crashed landed somewhere on their way to test facilities etc.. etc...

But if the flight manual says abt 500 deck, damn we will have heard abt since long if it didn't !!!! Pilots would hve complain, military would hve cancel orders etc.. etc... 465 is not 500. 35 kph at that time was a vital asset. It matters !

It's even illogical way to think, that UK did play some dangerous alchemy trying to convert their eng with 100 oct fuel if the enmy in front used low performing planes...

I urged all to stop searhing on the net or hanging too much time browsing the SpitPerf.cow website. Read books instead. Many are written by serious historians, not self proclaimed prophets.

And what ever... if you think that you can't handle the planes that your fav side gets in CoD... C'mon, it's a game, switch side and enjoy flying the finger pointed übers planes !

[robtek]

Of course i know that the chart was from a G model, to implement that i didn't know what i posted points to someone with more enthusiasm as common sense.

It was a example of typical deviations from a set value!

[Kwiatek]

Tomcat read German speed test for serial 109 E series not manual or prototype.

Most German speed test for serial 109 E claimed 467 km/h (E-3) - 475 km/h (E1) at sea level with 5- mintues emergency power ( 1.3 Ata). Such performacne is confirmed and corensponed very close to speed test made by other countries like Swiss ( E-3 with 601Aa), French or USA.

German test for serial 109 E-1 - 475-476 km/h at 0

http://www.wwiiaircraftperformance.org/me109/Me-109E1-1791.jpg


German test for serial 109 E-3 - 467 km/h at 0

http://www.wwiiaircraftperformance.org/me109/me109e3-1792.jpg

USA test for serial 109 E-3 - 467 km/h at 0

http://www.wwiiaircraftperformance.org/me109/Me-109E3-US.jpg

French test for serial E-3 ( radiator closed) - 480 km/h at 0

http://www.wwiiaircraftperformance.org/me109/Me-109E3-French.jpg

Swiss test for serial E-3 with Db601Aa - 467 km/h

http://www.wwiiaircraftperformance.org/me109/Me-109E-Swiss.jpg

Another German manual data for 109 E

http://www.wwiiaircraftperformance.org/me109/me109e-handbookcurve.jpg


There are only 2 different speed results :
- 1 is made for prototype V15a which clearly for me had not hydraulic supercharger but rather 2-stage - still it is for prototype 109E not serial production ones.
- 2 is manual for 109 but there is any information about these data

I belive that 109 E speed at sea level was between 467-475 km/h at 1.3/1.35 Ata (radiator 1/4 open) and faster speed could be possible to achived at 1-minutes take off power 1.4/1.45 Ata but truly speaking it is only for very short time. I dont belive any serial 109 E could do more then 490-500 km/h at sea level and even such speed probably could be achived with extremaly condition.

[TomcatViP]

Again, it's exactly what I am describing:

-Flight test of capt aircraft (we know tht both of those capt'ed 109s had structural failure as one of the french ferry/test pilot is famous for his flight testing postwar (Dassault)).
- Swiss 109 tht were not exactly in the same config of the German built (Yugoslavian were - Romanian shld be also)
-April 39 flight test...
There was only a minority of E model during the campaign of France. Most were D models. So V15 is an early test model. Just like saying in 50years tht tht F35 was not supersonic showing early flight test data. (Pls note tht I am not actually writing tht 109 shld be supersonic in CoD!!!)

....

Regarding the S/C on the 109, he he I am glad to read it from you now ;-)

But 450+ is the speed of the MS406 and Curtiss tht french used in majority. The D even was faster than those aircraft. I don't see how the E could hve the very same perf.

Note also tht cruise pow for the DB605 was ard 880HP giving G model a 450+ cruise speed. I don't see how the E cellule with 1100+ HP could be slower.

It's simply a question of logics (perf comparison, flight manuals, history books (reals ones), Maths and logics).

~S

[Kurfürst]

Tomcat read German speed test for serial 109 E series not manual or prototype.

Most German speed test ...

... you show are not performance tests at all. Two tests shown were aimed at showing the difference between guns installed/unistalled, slats sealed/unsealed.

for serial 109 E claimed 467 km/h (E-3) - 475 km/h (E1) at sea level with 5- mintues emergency power ( 1.3 Ata).

Compared to E-1 running at 1.35ata.... is it really a surprise that planes flying at lower power settings are SLOWER?

Such performacne is confirmed and corensponed very close to speed test made by other countries like Swiss ( E-3 with 601Aa), French or USA.

The French got around 480 with a less powerful engine. The Swiss conditions are unknown completely. The US did not test low altitude performance at all.

There are only 2 different speed results :
- 1 is made for prototype V15a which clearly for me had not hydraulic supercharger but rather 2-stage - still it is for prototype 109E not serial production ones.

Stop making up and spreading this BS again and again about the allaged lack of hydraulic supercharger... its getting tiresome.

The V15a was in every way akin to the 'serial production' 109E types. It was in every way identical to serial production machines, as clearly stated by the report itself.


I belive that 109 E speed at sea level was between 467-475 km/h at 1.3/1.35 Ata (radiator 1/4 open) and faster speed could be possible to achived at 1-minutes take off power 1.4/1.45 Ata but truly speaking it is only for very short time. I dont belive any serial 109 E could do more then 490-500 km/h at sea level and even such speed probably could be achived with extremaly condition.

At that is based on a Swiss graph of which's test conditions we know absolutely nothing, the idea that two uncorrected tests at 1.3ata were representative of 1.35ata performance etc.

It still begs an answer for the question why on earth did Messerschmitt contract for the delivery of 4000 planes at 65 000 Reichmarks each doing 500 km/h and not 460 on the deck.

I guess he was desperate for a 260 million RM deficit for violating the delivery contract's terms...

[Kurfürst]

I am looking for the following information.

What was the top speed of the Spitfire I, at +6 1/2 and +12 at SL, and what power it corresponded to.

What was the top speed of the Spitfire I, at +6 1/2 at rated altitude, and what power it corresponded to.

What was the top speed of the 109E, at 1.3/1.35ata at SL and at rated altitude, and what power it corresponded to.

[41Sqn_Stormcrow]

.
It still begs an answer for the question why on earth did Messerschmitt contract for the delivery of 4000 planes at 65 000 Reichmarks each doing 500 km/h and not 460 on the deck.

I guess he was desperate for a 260 million RM deficit for violating the delivery contract's terms...

Messerschmidt did not guarantee 500 kph but 500 +/- 5% so if each 109 would have been at 475 kph it would have been perfectly acceptable.

This means however also that it can fairly be assumed that the speed on the deck should be 475 kph at minimum.

[TomcatViP]

Well Storm,

if you sell 4000 unit of a product that all meet only minimal requirements, you certainly won't sell 29000 more.... even in the complete madness of the Nazi regime. Hve a look at the 210/410 scandal (read the "Fana de l'aviation" 2011 paper ;-) )

[Timberwolf]

LoL Everyones talking about top speeds, and Alt speeds ... Most people is using a test from other people and countries. That would fuel up a 109 take it up and see.. One of the most major factors left out was the use of Synthetic fuel that the Germans used. And American testing on German Aircraft. The American fuel which had a higher octane And had a great affect on speeds even more with supercharged planes Yet no one has talked about it just lines from other websites ..and those don't have which fuel was used on the test

[TomcatViP]

LoL everyones talking about top speeds and Alt speeds ... Most people is test from other people and countries that would fuel up a 109 take it up and see.. One of the most major factor the use of Synthetic fuel that the germans used To American fuel which had a higher octaneand had a great affect on speeds even more with supercharged planes Yet no one has talked about it just lines from other websites ..and those don't have which fuel was used on the test

How right you are.

But perso I became allergic to all fuel's grade discussion with month arguing my best (with honesty) on the recently closed thread abt 100oct fuel ;)

[Kurfürst]

First, thank you for putting time in an obviously well thought out and coherent posts. Its a rare thing to see something like that on this board.

And now the barrage ;)


The disagreement can be summarised as:

Position 1 (Fast guaranteed 109s): Messerchmitt guaranteed 500kmh on the deck and 572kmh max TAS for the 109E. The E1 prototype duplicates these figures theoretically once the actual flight tests are corrected for a measured engine deficiency of around 50PS.

Position 2 (Slow low 109s): Actual flight tests of production 109Es, both by Messerchmitt and by foreign governments on captured 109Es, indicate lower performance (primarily at low alt). Speeds are around 475kmh IAS/TAS on the deck and 560 kmh max TAS.

I support position 2, for reasons as follows.

Here is all the test data summarised. I am appending the data links at the end of the post. Most of this data is on "competing" websites (http://kurfurst.org and http://www.wwiiaircraftperformance.org). Most of it is on both, and it is exactly the same data..... however the interpretation is different. I will give kmh and mph figures, plus boost psi and ata.

http://i406.photobucket.com/albums/pp142/wjhawaii/109_performance.jpg


Postion 1 (Fast guaranteed 109s) requires explanations to why all the 109E actual flight tests show lower performance than "guaranteed".

Similarly Position two (Slow 109s based on trials with uncorrected/unknown conditions) requires explanations as to why ignore the most detailed actual flight tests which the manufacturer choose to guarantee.

A good start is assigning lower significance to tests on captured aircraft, as these may not operating at maxiumum efficiency (for various reasons). However this makes no real difference to the data set, as the flight tests (besides the E1 prototype) are all similar. The only exception is the Russian captured aircraft which appears to be a (low performance) outlier at low altitude, and can perhaps be discarded from consideration.

For test 1 (E1 prototype) the converted (theoretical) data appears reasonable. The engine power deficiency was measured on the test stand and used to provide a theoretical correction to actual flight data.

The Russian results are probably easy to understand if anyone looks at the climb curves. They show an abnormally steep fall of climb rate near SL, which is a clear indication something was wrong with near-SL power outputs of the specific plane.

For tests 2 and 3, the suggested reason for low performance is that the results are not corrected for nominal DB601A output, as was done for the E1 prototype (http://kurfurst.org/Performance_tests/109E_MP_E3_1792/WNr1792_E3_MP16feb39.html). However this begs the question, why were multiple production 109Es failing in tests to reach their guaranteed performance because of underperforming DB601s? This seems an unlikely scenario, and rather a bone of contention between Messerchmitt and Daimler Benz!

While Test 1 was made at 1,35ata and higher output, with known (measured) engine outputs Tests 2 and 3 were made with a 1,3ata - test 2/3 were flown at lower boost. This explains some of the difference but not all.

The important difference between Test 1 and Test 2/3 however is that while Test 1 is a performance test, and wanted to obtain accurate and absolute performance figures for the whole altitude spectrum, Test 2/3 were never intended to do the same.

Test 2/3 were about finding the relative difference in performance in various aerodynamic conditions, presumably for seeking out the viability for future improvements (guns installed not installed etc.). All they wanted to gain is relative speed difference on the same plane to get an idea how much drag penalty these items induce. They were never meant to be representative performance flight trials.


For test 5, the explanation for underperformance relates to the function of the DB601 supercharger.

Also for Test 2 and 3. One part that is not mentioned in the table that all flight trials (none of which we know the supercharger setup) show very close agreement, within a few km/h to Test 1's performance with the high altitude supercharger speed in operation.


The hydraulic supercharger coupling of the 109 was intensely interesting to the British and there is a couple of very good, detailed explanations of it's operation in the period press:

www.wwiiaircraftperformance.org/me109/DB-601A-Flight-7Nov40.pdf
http://www.flightglobal.com/pdfarchive/view/1942/1942%20-%200516.html

Both the DB601 and Merlin had the same problem...a supercharger powerful enough to allow high altitude performance would give so much overboost (unthrottled) at sea level to cause predetonation and engine damage. The Brits developed a boost controller that automatically throttled the supercharger inlet to avoid overboost. The Germans worked out an elegant hydraulic supercharger coupling that spun the supercharger impeller slower at sea level and faster at height.

There seem to be a misunderstanding. You seem to assume that the British used a boost controller, the Germans did not, and relied solely on the barometrically controlled hydraulic supercharger coupling and - did not have a throttle on the engine at all! :D

This is however a false assumption, as apart from controlling the supercharger, the DB engines had automatic boost controller as the RR engines did. In fact those engines that did not and the throttle was controlled manually were the exception.

The hydraulic coupling provided the apprx. amount of boost needed, usually a bit more just to make sure, but fine adjustment was made by the throttle on the DB, which limited boost to the nominal pressures.

The DB601 hydraulic coupling had two oil pumps which pumped oil into the engine to impeller junction. One pump operated continuously but insufficiently for efficient coupling, allowing slippage of about 30%. As altitude rose, a barometric control increased the action of the secondary oil pump, reducing slippage to the minimum possible, about 2%. The corresponding impeller ratios were 7.2:1 at sea level rising to 10.2:1 at FTH.

The continuously varied supercharger output accounts for the curved nature of the 109 speed vs alt curves (e.g test 4) Unfortunately some tests seem to omit data points in favor of straight lines, making it hard to assess whether the curves are characteristic of the hydraulic coupling or not (e.g test 5

There seem to be an assumption that the supercharger output on the DB engine was continously varied. However it is not true to the 1st s/c speed, ie. the Bodenlader speed or MS gear in British terminology, at which only the first, constant supply oil pump supplied oil to the hydraulic clutch, and was therefore a fixed speed unit.

The second variable oil supply pump was only engaged at around 1.5-2 km altitude, above which the s/c output was contiously varied indeed - but not before that.

This characteristic is clearly visible on DB power curves (straight power line between 0-2km).

The (fast guaranteed 109s) explanation for the test 5 underperformance is based on the hypothesis that the hydraulic supercharger setup can be altered in tests to act a two speed supercharger, and the Swiss were testing in high altitude configuration at all altitudes including at ground level. As a consequence the high altitude speed is about right but the sea level speed is low (http://kurfurst.org/Performance_tests/109E_SwissJ347/109E_J347.html)

Correct. It should be noted that this explanation gives a rational explanation for the great difference between various measured values. We are not talking about 10-20 km/h but 40 km/h speed difference, which is rather tricky to explain with individual variation between planes.

Also it not only true for the Swiss testing (conditions completely unknown, but the lack of any curvature and good agreement between V15a Hoehenlader results also suggest this), but also to the two other German 109E flight tests.

This does not seem to be possible in light of the operation of the hydraulic coupling as explained in the references above.

You are simply wrong.. there is no technical difficulty in doing so.

Manual operation of the variable oil pump (if possible) would have the following effects:

* If the variable oil pump is set to off, impeller slippage remains at 30%. Aircraft will perform normally at sea level, but boost will decay rapidly with altitude with consequent underperformance.

Yet this is not what is happening in real life. As a matter of fact the variable fuel pump (2nd speed) is completely off even in normal operation up to around 2 km, ie. impellor slippage is constantly at around 30% up to that altitude. Yet the boost does NOT fall, its constant 1.3ata.

In short, the DB 60x series supercharger's first speed is ALWAYS fixed ratio, yet as opposed what you speculate, that the engine boost would decrease above sea level, it doesn't. On the contrary, power curves show it increases, peaking out at about 2000m, where the variable oil pump is engaged by barometric control.

The reason is simple, when the slippage is at 30% (first s/c or 'Bodenlader') the supercharger compresses far more air (at around 1.6-1.7ata) than the necessary (1.3-1.45 ata), but the boost regulator only feds the engine with the necessary amount. This also means that at near SL the air is much more compressed, than a bit above, and as a result heats up more, decreasing output a bit.

The actual pressures can be seen on this graph on a 109G. See the difference between Ladedruck (boost) and Geblaesedruck (which is the pressure in the supercharger itself): http://kurfurst.org/Performance_tests/109G1_messung601e605a/files/blatt6.jpg

* If the variable oil pump is set to maximum, impeller slippage is held at 2%. The engine will be highly overboosted at sea level and will be unable to perform at all!

Nope, the engine won't be overboosted. The supercharger with minimum slip will develop a lot-lot more pressure at low levels, heat up the air a lot more in the process, decrease output greatly as a result.

What will simply happen is that the supercharger will develop at low altitudes a lot more pressure than needed, and before it enters the engine it will be throttled down to the nominal levels.

The whole 'not possible because of the use of a hydraulic coupling' is nonsense. The only thing the hydraulic coupling change is the gear ratio of the supercharger, between 7.2:1 and 10.2:1, just like a mechanical gear in a more simple two-speed supercharger would do, the only difference is that the hydraulic is capable of any intermediate interval, ie. any ratio between 7.2:1 and 10.2:1, the mechanical linkage is not.

This also contradicts the idea that the test 1 (E1 prototype) performance is from a DB601 with hydraulic supercharger coupling manually manipulated to act as a two speed system. The data explicitly refers to a two speed system, so in the prototype it appears that the supercharger is an earlier direct and not hydraulic type.

There is no such thing stated in the E1 prototype. The report Blatt 6 curve shows the supercharger operation in Bodenlader and Hoehenlader, which is always used by Germans to describe the low altitude (MS) and high altitude (FS) supercharger speeds/gears.

Furthermore Rechlin's much later trials with G-6 show exactly the same operation of high/low supercharger gears. Unless you want to tell me that hydraulic coupling was also missing on the DB 605A/109G-6...

http://kurfurst.org/Performance_tests/109G14_May44trials/109G-6_DB605A.jpg

The fact that the E1 prototype achieved higher sea level performance but similar maximum performance suggests that the hydraulic coupling had an efficiency penalty at low altitude as compared to a direct coupling. But the advantage of the hydraulic supercharger coupling in reducing pilot load in combat was probably considered an overriding factor.

The whole of this thesis assumes that the E-1 prototype had more power at low altitude because it supposedly would have used a direct coupling (something that is nowhere stated in the report) which was supposedly] more efficient at low altitudes, and in the end gave more power to the propeller.

Problem is that all of the above runs aground since the report clearly states the aircraft doing 493 km/h with 951 PS power, at 1.31ata with the supposedly more powerful engine.*

For comparison the DB 601A-1 static output at SL was 990 PS at 1.3ata, and that of the 601Aa at 1.35ata was 1045 PS.

In short the tested aircraft's propeller had exactly the same power as serial production machines, regardless of what happened in the engine before that.

*The results were later corrected to 996 PS, the nominal output in flight.



I am not aware of other explanations of underperformance in the other actual 109E flight tests.

As to the Messerchmitt guaranteed performance, I am somewhat intrigued as it seems serial production 109s with hydraulic supercharger couplings did not meet it (at least at sea level).

1, All Bf 109s with DB engines had hydraulic supercharger couplings

2, The guarantee was for 1.35ata performance, +/- 5% for 500 km/h. That means that anything between 475 km/h and 525/h is OK for acceptance, for an Emil with DB 601Aa and operating at 1.35ata.

Compared to that, it would the French got around 480 km/h at 1.3ata from a crashed aircraft and the Germans iirc 474 km/h for another test machine, again at 1.3ata. In both cases the nominal output of the engines was at least 55 PS less than that of the Aa engine.

I would say serial production machines stack up really well to the specs.


So based on the above a reasonable (serial 109E with hydraulic supercharger) performance is based on the actual flight tests (minus the prototype):

475kmh IAS/TAS at SL 1.35ata 2400rpm
560 kmh TAS at 5000m 1.35ata 2400rpm top speed

And this is based on which test or official data...?


1.35ata is 5 min combat limit. It is rather open to debate what effects sustained 1.35ata should have in the sim, what performance 1.45ata should give and whether it should work at all at height (historically it is a takeoff only boost after all).

Uhm, so by what connection how does 1.35 ata performance come into the picture? You basically show threww German tests (at uncorrected power) at 1.3ata, which only show performance for SL, and suddenly 1.3ata performance is now the same as 1.35ata performance?

How are uncorrected 1.3ata tests are in connection with 1.35ata performance?

[camber]

Dear Kurfurst and others

Thank you for the response. That was exactly the critique I was looking for.


While Test 1 was made at 1,35ata and higher output, with known (measured) engine outputs Tests 2 and 3 were made with a 1,3ata - test 2/3 were flown at lower boost. This explains some of the difference but not all.

The important difference between Test 1 and Test 2/3 however is that while Test 1 is a performance test, and wanted to obtain accurate and absolute performance figures for the whole altitude spectrum, Test 2/3 were never intended to do the same.

Test 2/3 were about finding the relative difference in performance in various aerodynamic conditions, presumably for seeking out the viability for future improvements (guns installed not installed etc.). All they wanted to gain is relative speed difference on the same plane to get an idea how much drag penalty these items induce. They were never meant to be representative performance flight trials.

Also for Test 2 and 3. One part that is not mentioned in the table that all flight trials (none of which we know the supercharger setup) show very close agreement, within a few km/h to Test 1's performance with the high altitude supercharger speed in operation.?

I agree with you that Tests 2 and 3 are comparative (interestingly the changes made never affected performance). I consider them useful for consideration as they are among a limited range of official Messerschmitt 109E flight tests I am aware of, although they are certainly non-optimal (comparative, no height curve, sea level speed probably extrapolated etc.). More German speed tests would be be very useful, a few more and we could remove these ones if desired.

I would say however that provided the rated conditions are known, the "control" speed (i.e without configuration changes, not that this changed anything) should be considered in the data set in light of stated boost (1.30ata).

But I can't agree that (lack of) engine power correction is a good explanation of low altitude underperformance in multiple tests (i.e. other than test 1). It suggests that 109E underperformance due to DB601 defficiency is typical and might be a factor in actual production aircraft (unlikely). In this case the 109s underperform but it is a DB rather than Me problem.



There seem to be a misunderstanding. You seem to assume that the British used a boost controller, the Germans did not, and relied solely on the barometrically controlled hydraulic supercharger coupling and - did not have a throttle on the engine at all! :D

This is however a false assumption, as apart from controlling the supercharger, the DB engines had automatic boost controller as the RR engines did. In fact those engines that did not and the throttle was controlled manually were the exception.

The hydraulic coupling provided the apprx. amount of boost needed, usually a bit more just to make sure, but fine adjustment was made by the throttle on the DB, which limited boost to the nominal pressures.


Yes, I did make that (false) assumption. In my defense, I will say that I was seduced late at night by the romance of a boost control system engineered by hydraulic slippage of the supercharger by German engineering geniuses. I will look further into the total system but point conceded as the system you describe makes more sense.

This certainly knocks over one of the legs of my argument (but not all ;)). With separate boost control and provided ability to alter the variable oil pump operation, the coupling could indeed act similarly to a two geared system. However, it is still a hypothesis that the Swiss 109 was tested in high altitude mode at all altitudes (decreasing low alt performance). An alternative hypothesis is that the speed/height curve has been simplified as a straight line, similarly to the original 109E specification. Without actual data points we can't tell.

This unfortunately gets us back to the original problem of a somewhat large range of possible low altitude 109 performance, with reasonable grounds (in my opinion) to argue both ends of the spectrum:

* A guaranteed technical specification
* A prototype that meets the spec provided engine power is corrected
* Multiple flight tests (with boost variability) that are specification "passes" for max speed but around the pass/fail level at sea level speed. Some plausible but unproveable hypotheses are presented for underperformance in these real tests.


The guarantee was for 1.35ata performance, +/- 5% for 500 km/h. That means that anything between 475 km/h and 525/h is OK for acceptance, for an Emil with DB 601Aa and operating at 1.35ata.

Compared to that, it would the French got around 480 km/h at 1.3ata from a crashed aircraft and the Germans iirc 474 km/h for another test machine, again at 1.3ata. In both cases the nominal output of the engines was at least 55 PS less than that of the Aa engine.


Actually better, I get ~480kmh at 1.26ata from my pressure conversion for the French test. I'm not sure what the relevance is to the Aa export motor (comparison to Test 5?)


And this is based on which test or official data...?

Uhm, so by what connection how does 1.35 ata performance come into the picture? You basically show threww German tests (at uncorrected power) at 1.3ata, which only show performance for SL, and suddenly 1.3ata performance is now the same as 1.35ata performance?

How are uncorrected 1.3ata tests are in connection with 1.35ata performance?


Well, I admit that was rather sloppy, but we do have to deal with a set of tests with varying boost levels :). It was a rough estimation of performance from the flight tests excluding the prototype and Russian test, to answer my original question : "if you had to derive a single set of figures, what would they be?". A better method would be to attempt to correct all speeds for a standard boost (1.35ata) in some manner, then average. Otherwise one can only say (based on flight tests minus tests 1 and 7)

SL speed 465-480kmh at 1.25-1.3ata
Top speed 547-565kmh at 1.25-1.3ata

With a theoretical correction to 1.35 ata, I would estimate we are looking at a low specification "pass" at SL and close to bang on spec at height.

I've seen such a acceptance diagram from Meserschmitt 109's, but i don't know which series it was, anyway the general deviation was about 10 km/h below the guaranteed value, iirc. A few were above, the majority slightly below and five had to be refurbished because they've failed.
Found it: http://www.kurfurst.org/Performance_tests/109G_Erlatrials/Erla109G_13speedrun_scatter_web.jpg

Looking at these tests for the 109G (Thank you), it appears (although the plot is a bit hard to make out) that acceptance testing was based on max speed only. The failed 109Gs are underperforming at height, and it doesn't appear that SL performance is being considered. The pattern of the true max speed average falling a little under the spec average seems rather plausible as well.

Based on this all, I would suggest that "typical" series 109Es
* Performed close (maybe a little below) to their max speed average spec at 5000m (572 kmh TAS)
* Performed close (but above) their minimum "pass" rate at sea level (475kmh IAS/TAS)

Based on the 109G test data I would hypothesise that slight deviations under sea level minimum spec might be possible in individual "passed" aircraft (provided they passed the max speed test at height).

From the CloD point of view we are perhaps over-focussed on the sea level performance. We spend a lot of time chasing and being chased at sea level in 1v1 battles, and when we "test" the aircraft we skim the waves in a way no actual test pilot would care to do on a routine basis ;)

camber

[IvanK]

Some more info.

I have a Russian (What I think) is an Engineering and Performance apprasial on the BF109E3 done in 1941. Its 117 pages and very detailed but being written in Cyrillic is hard going. Evident in the document the E3 has Auto Prop pitch.

http://i40.photobucket.com/albums/e215/zulu64/Russ109E3Perf2.jpg

Buried in the document for what its worth is this graph:

http://i40.photobucket.com/albums/e215/zulu64/Russ109E3Perf.jpg

Looks like two sets of TAS v Altitude lines for different conditions and two sets of Time to height lines "t".

Be nice if a Russian speaker could repost the graph with the legends to the lines and the statement at the bottom in English.

[ZaltysZ]

This is level speed (TAS vs Altitude) and climbing (Climb time vs Altitude) chart. Units: m, km/h, min. I will look at this book later for translating the legends, because these are abbreviations in chart.

EDIT #1: curves with bubbles - "Manufacturer data", curves with crosses - "Data of Research institute (НИИ - Научно-исследовательский институт)"
EDIT #2: Tests were done at 2400RPM/1.35ATA. This is true for climbing test only until 5 minute mark, after which lower power setting was used.

[camber]

IvanK,

Nice document. That is clearly the full appraisal that goes with Test 7 (Russian captured E3) in the original thread post. The curve matches pretty much exactly.

The Russians clearly took the Messerchmitt guaranteed 109 performance seriously.. they have plotted it alongside. If I was shopping for a secondhand 109E for the local pylon races I think I would give that one a miss, it really seems a bit of a lemon.

Cheers, camber

[5./JG27.Farber]

In what conditions were all these aircraft captured? I remember reading somewhere the 109 needed a service after 10 flying hours.

[JG4_Helofly]

Is it still a discussion about correcting performance in the game or do we fight the real BOB again?
If it's still about the game, then I doubt that taking some perf. tests from captured aircrafts will get us very far. It's pointless to discuss about taking such data for the FM. Why? Simply because it would be impossible to estimate the average performance of several thousands of planes at a given time in a given battle. Especially when you don't have a representativ number of tests.
How can it be justified to change the top speed of the 109 based on a few testflights from foreign countrys?
And if we would go down that road, how about low production quality in late war scenarios? Or other factors who would affect performance?

IMO the only way to have acceptable performance data is to take the theoretical values which should be reached by production aircrafts under normal conditions. Everything else is just BS.

[camber]

Is it still a discussion about correcting performance in the game or do we fight the real BOB again?

Well actually neither, it was a discussion about whether the actual 109E performance possibly deviated from (or within) the Messerchmitt specs, based on German and captured aircraft tests. Of course then there is a further argument about whether it would be best for which data to be in CloD. Currently the sea level 109 is too slow for either side of the argument.


If it's still about the game, then I doubt that taking some perf. tests from captured aircrafts will get us very far. It's pointless to discuss about taking such data for the FM. Why? Simply because it would be impossible to estimate the average performance of several thousands of planes at a given time in a given battle. Especially when you don't have a representativ number of tests.

I disagree. It is never pointless to examine actual flight tests provided their limitations are considered...but you are correct captured aircraft tests should be treated with extra suspicion, as in the original post.


How can it be justified to change the top speed of the 109 based on a few testflights from foreign countrys?
And if we would go down that road, how about low production quality in late war scenarios? Or other factors who would affect performance?

IMO the only way to have acceptable performance data is to take the theoretical values which should be reached by production aircrafts under normal conditions. Everything else is just BS.

That is a valid position for argument. However I do not think that means alternative arguments are BS. I would also say the Messershmitt specs are +/- 25 kmh at sea level, even adjustments within these bounds may change your online experience with such closely matched aircraft as Spits and 109s.

camber

[JG4_Helofly]

@ Camber. I understand that you want the game to be as close as possible to RL. But we don't have the data to do this. If you had several thousands of test data from production aircrafts, then it would be representativ. Since we don't have this amount of data everyone can pick one of the tests and say: "but plane X was 25 km/h slower in this test". People who like plane X will say: "But it was 25km/h faster in an other test".
And there will be arguments about production quality, fuel availability, maintenance problems etc.
And that's exactly what we have now. That's why we need a solid base. Data we can agree on. That's why the only realistic approache is to model the planes according to standard specifications and taking all other variables out of the equation. Otherwise we will continue to argue about every km/h and everyone will pull out the test result which fits the agenda.

IMO the only alternative would be to have a performance spread of +/- 5% for every plane. So every plane would have it's standard performance values it should reach, but you could get a plane with a few % worse or better performance.

I really don't see how you could do it otherwise without having arbitrary performance values.

[Crumpp]

I really dont understand this discussion, any 109 not meeting the guaranteed values from Messerschmitt was rejected by the Luftwaffe to be refurbished by Messerschmitt.

Each and every plane had a acception flight to prove it delivered the guaranteed values.
If there should be a deviation from the guaranteed values programmed in game, this deviation must be valid for ALL planes in this sim.


Exactly.

That is how airplanes work. Why anyone would think a customer would pay for something that does not work as advertised is beyond me.

[camber]

@ Camber. I understand that you want the game to be as close as possible to RL. But we don't have the data to do this. If you had several thousands of test data from production aircrafts, then it would be representativ. Since we don't have this amount of data everyone can pick one of the tests and say: "but plane X was 25 km/h slower in this test". People who like plane X will say: "But it was 25km/h faster in an other test".
And there will be arguments about production quality, fuel availability, maintenance problems etc.
And that's exactly what we have now. That's why we need a solid base. Data we can agree on. That's why the only realistic approache is to model the planes according to standard specifications and taking all other variables out of the equation. Otherwise we will continue to argue about every km/h and everyone will pull out the test result which fits the agenda.

IMO the only alternative would be to have a performance spread of +/- 5% for every plane. So every plane would have it's standard performance values it should reach, but you could get a plane with a few % worse or better performance.

I really don't see how you could do it otherwise without having arbitrary performance values.

Actually I pretty much agree with you. My original analysis was an attempt to get as close as I could (with the limited data available) to "typical" 109E performance for historical purposes as a starting point for FMs. But I actually don't believe CloD is best served by neccessarily served by setting such values as single "cloned" variants into the game. Personally I think the sim is best served by getting performance within into the range that is consistent for historical performance (which is imprecise!), then making some subjective judgements that (if possible) allows matchups that are rewarding for both red and blue. For example the current Spit II vs 109E matchup is good, it relatively approximates a Mk1a +12psi vs 109E (at around 30kmh too slow at SL for both!). Based on data I believe historically the Mk1a would have actually been a bit quicker on the deck, but having them exactly the same speed is arguably within historical range and makes for satisfying online experiences.

Your idea of using factory data with a "performance slider" would also work well for the same reason, but I am not sure if there is much likelyhood the devs would ever do this!

Cheers, camber

[5./JG27.Farber]

How much fuel was in the aircraft during any of these tests? That could be another factor that affects top speed. What if the German tests were with half a tank of Benzine and the Russian/UK/USA tests were with of full tank of there own grade of fuel? This would be a big difference. around 200kilos or 440lbs... Also is the aircraft clean and trimmed properly? Is the airframe bent from battle damage or crash landing?

[Crumpp]

Guys,

Airplanes also work as any other machine. They require break in periods, have an area where their performance will peak, and they lose performance if the engine/airframe is abused or aged.

Military aircraft in war are consistently abused. They operate from rough fields, suffer weather, and often poor piloting from inexperienced pilots.
The environment plays a huge role on their performance. Is that data corrected to standard? ALL OF IT? The engine is data is adjusted for a standard day while the engine is adjusted by a mechanic on the day he picks up the wrench. That means in some engines, depending on the design, you will not develop the calibrated manifold pressure/rpm depending on density altitude while others will meet or exceed that by a small percentage.

Airplanes also require an extraordinary amount of maintenance. Much of that maintenance is specialized specific knowledge to that design. That is why by convention, the manufacturer publishes a maintenance manual on every component and subcomponent as well a consolidated type specific instructions. These instructions are extremely detailed and specify exactly what the mechanic or maintenance personnel can do. The "How to" is compulsory and part of the airworthiness instructions of the aircraft. The "When to" is more flexible and up to the operator's as well maintenance personnel.

For example, a 10 hours service on break in requires you to change the mineral oil in the engine and examine the filter to ensure the engine is making the appropriate amount of metal as the parts settle in.

Most of the engines during WWII used what is today termed an "oil screen" not an oil filter. They called it a filter but don't confuse it with the spin off type found in your car. There are some important differences in reality that have no bearing on a game.

Each engine is a little different by on average you are going to change the oil at least twice and examine the filter during break in. When the rings seat and the amount of metal being made levels out you can tell because the oil consumption will stabilize. Then you can generally change to an ashless dispersant oil for normal use.

You don't have to the "10 hour" maintenance at exactly 10 hours. You can fit it in as operational demands require. You do have follow the "how to" instructions exactly to the letter when you decide to do it.

If you don't all of the required and specified maintenance instructions including the specific lubricants and fuels, it will generally not work properly.

For example, it is very easy to damage a propeller just lubricating it. When it starts spitting grease, it becomes unbalanced and further damage occurs. All of this effects the power the engine can produce and the performance one will get.

[pstyle]

Guys,

Airplanes also work as any other machine. They require break in periods, have an area where their performance will peak, and they lose performance if the engine/airframe is abused or aged.


exactly.
Just look at an F1 team
Two drivers (team mates) can be in just about as identical car as possible, both on the same track, under the same weather conditions. Yet you get all sorts of different performance, because so many other factors influence the system.

[5./JG27.Farber]

You might find German engines are run in at the factory. As for the rest of your post Crump, exactly! - With these aircraft being captured they are not going to be clean crisp factory models either. Their going to be thrashed work horses proberbly in poor condition due to shortages and desperate actions..

[camber]

You might find German engines are run in at the factory. As for the rest of your post Crump, exactly! - With these aircraft being captured they are not going to be clean crisp factory models either. Their going to be thrashed work horses proberbly in poor condition due to shortages and desperate actions..

I agree. Except for the navigation error guys, imagine going on the reciprocal compass bearing, landing, quietly shutting everything down then looking up at the armed people around the plane.

But to clarify, you are quite right that comparing captured a/c tests against the official Me compliance tests (and going for captured) would be inappropriate. However the original thread post doesn't make that argument..it notes that what captured data there is agrees with two Messerchmitt tests and a Swiss export model, except for a Russian test which is very slow on the deck. Kurfurst has presented reasonable arguement against these tests..I don't necessarily agree but they are valid technical arguements.

My question to you would be, given the keys to CloD, what would you set the 109E performance to be? Within the 109 guaranteed spec, that +/-5% makes a difference with the close match between Spit and 109. And we don't have a lot of variants to work with here.

There is not many actual tests, what would really clinch the issue is the RLM compliance data for the 109E (which we don't have as far as I know). This is the equivalent of RAF RAE data, i.e taken not by the manufacturer but the (hopefully skeptical) client. 109G tolerance tests appear to show the pass (to service)/fail (back to the factory) performance being evaluated only for max speed (not sea level). The average top speed at altitude is a little under the average spec speed but still easily passing, which seems rather plausible.

So my current position (based on thread discussion above) is that the most appropriate (typical, historical) performance for 109Es if we must go with a single cloned aircraft in the simulation is low (but pass) spec at sea level and about average spec at height.

But despite this if you really gave me the keys to the Clod FMs, I would actually use the Messerchmitt guaranteed data. I would then set Spit I performance to RAE data, and with +12psi, which should give a nicely balanced Spit vs 109 matchup even on the deck. Single cloned aircraft are pretty unhistorical anyway, better to balance the simulation (once you are within the zone historical and aircraft-aircraft imprecision). People often hate the concept of balance, but what to do once you are within the historical imprecision zone, and you are giving everyone on each side exactly the same aircraft?

Cheers, camber

[robtek]

I believe the variable of the pilots is enough to simulate the factory tolerances.

Especially if wrong engine management gives feelable results, or engine temperatures acting more to the load of the engine instead of rpm.

If one is flying by the book he should have a fine performing machine, if one is riding rough he should have a short living advantage followed by a lame ride.

[notafinger!]

Personally I think the sim is best served by getting performance within into the range that is consistent for historical performance (which is imprecise!), then making some subjective judgements that (if possible) allows matchups that are rewarding for both red and blue. For example the current Spit II vs 109E matchup is good, it relatively approximates a Mk1a +12psi vs 109E (at around 30kmh too slow at SL for both!). Based on data I believe historically the Mk1a would have actually been a bit quicker on the deck, but having them exactly the same speed is arguably within historical range and makes for satisfying online experiences.

I agree 100%. I would prefer the devs give us FM's that fit the historical anecdote of the battle, yet are fun & challenging to fly online. The three major fighters should each have distinct advantages/disadvantages & be competitive when flown to their strengths. It will be impossible to get 100% realism so at least give us something that feels right and is fun to play for both sides.

[tools4fools]

The three major fighters should each have distinct advantages/disadvantages & be competitive when flown to their strengths.

So a Hurricane flown to its strenght should be competitive with a 109 flown to its strenght?
Or a G50 vs a Spitfire?
How would that be possible?

Don't think so, they should perform as they did and if one plane was noticable inferior in overall combat capabilities then it should be that way.
+++++

[notafinger!]

So a Hurricane flown to its strenght should be competitive with a 109 flown to its strenght?
Or a G50 vs a Spitfire?
How would that be possible?
Don't be daft. If a Hurricane's strength should be it's turning ability and a 109's it's speed then the respective pilots should have two very different fighting styles. The pilot that tries to fight the other man's game will lose. In the current version of the sim the Hurricane is useless as it does nothing well, hence very few people fly it. If the devs were to take the current FM's and simply swap the the turning abilities of the Hurricane and Spitfire & copy the speed/climb info of the Spit II into the Ia I think you would see a much more dynamic and enjoyable experience online.

Don't think so, they should perform as they did and if one plane was noticable inferior in overall combat capabilities then it should be that way.
+++++
Who is to say how they did perform? Nobody alive today can say that, certainly nobody playing this game. Instead we have a mountain of conflicting technical information & pilot accounts that prove nothing. What we do have is historical anecdote that says the Spit & 109 were about equal in most aspects (one a little faster, the other turns a bit better) and the Hurricane was a little slower but turned the best. There are going to be rivet counters who will never be pleased but the vast majority would accept FM's that simply were in-line with the accepted lore of the battle.

[CWMV]

No no no no no!
Accuracy over all else. Arcade players be darned.

[Seadog]

Historically, under 10,000 ft, the Hurricane I was superior to the Me109e due to its better turn radius, and with 12lb boost, better climb rate, and was only slightly slower. At very low altitudes, say under 5000ft the Me109e was at a severe disadvantage as it could no longer dive away to disengage, and it did not have a sufficient, if any, speed advantage when the Hurricane pilot "pulled the plug" and the Hurricane could easily turn inside the 109e.

[JtD]

It would still be able to extend using negative g manoeuvres. Maybe the Hurricane was the superior dogfighter down low, but I don't think it was the superior fighter aircraft.

[Seadog]

It would still be able to extend using negative g manoeuvres. Maybe the Hurricane was the superior dogfighter down low, but I don't think it was the superior fighter aircraft.

No, it wasn't the overall equal of the 109E, and at high altitude was at a severe disadvantage, but then the main role of the Hurricane (and Spitfire) was to shoot down Luftwaffe bombers, and engaging the fighter escort was a very secondary task. The 109E had a favourable kill ratio over either RAF fighter because they were trying to engage the bombers while the 109s were, largely, freed to bounce the RAF fighters from above.

[tools4fools]

In the current version of the sim the Hurricane is useless as it does nothing well, hence very few people fly it

And of course the G50 is useless too, hence very few people fly it, so we improve that one to a little bit as well, right?

No no no no no!
Accuracy over all else. Arcade players be darned.

My vote goes for accuracy as well.
With a performance variable added.

[notafinger!]

My vote goes for accuracy as well.
With a performance variable added.

Be sure to tell the rest of us when a level of accuracy has been reached that is acceptable to both red & blue. The real arcade players are the ones who need their plane to have every advantage. The performance variable is the person sitting behind the controls.

[tools4fools]

when a level of accuracy has been reached that is acceptable to both red & blue.That's where the problem starts - people that think 'blue' and 'red'.
It will never be acceptable to them.

Performance variable would a a plus/minus 5% power output from the specs for all planes, or something like that.
That would be realistic in the first place and challenging for the game too - nobody could rely on the performance of their planes.
But that's the last the 'red' and 'blue' thinkers would like.

[bw_wolverine]

I think a performance variance included in the sim would be great.

I also think PERSISTANT performance variance for your online aircraft would be great.

Par Examply: I take a Hurricane and it gives me +5% performance over the 'baseline' Hurricane. I'm very happy. I fly this aircraft until I crash it, or bail out of it, or quit the game while in the air. It's gone. Next time I load a Hurricane, it gives me a new aeroplane with a new +/- variance. Maybe this time I get -2.5%.

I guess the only problem would be that people would instantly attempt to crash the bad aircraft to get a better one. :/ Stupid gamers.

[von Brühl]

I guess the only problem would be that people would instantly attempt to crash the bad aircraft to get a better one. :/ Stupid gamers.

LOL, that was my first reaction, "I wonder how many you crashed to get the +5%?". There's always people gaming the system. What you shouldn't get is a report telling you the performance increase/decrease of your plane, it's simply your plane. You can figure out on your own what the limits are, if you are good enough to reach them.

[Kwiatek]

Historically, under 10,000 ft, the Hurricane I was superior to the Me109e due to its better turn radius, and with 12lb boost, better climb rate, and was only slightly slower. At very low altitudes, say under 5000ft the Me109e was at a severe disadvantage as it could no longer dive away to disengage, and it did not have a sufficient, if any, speed advantage when the Hurricane pilot "pulled the plug" and the Hurricane could easily turn inside the 109e.

It wasnt superior but with +12 lbs emergency boost it was also seriously opponent for 109 at low altitude. Polish Pilots from 303SQN proof these enough. Hurricane I with +12 lbs and CSP could be very close to 109 E speed at low level alt. Of course 109 was better plane these is not question about it but in some cases Hurricane could be fair opponent ( better turn at low to medium alts, comparable climb and speed at 12 lbs emergency power at low alts).

I read some interesting combat raports from Skalski who had fight with 109 E starting at higher alts when 109 attacked him and they made circles and 109 was very close in these to Hurricane but when fight drop to medium and low alts Hurricane could outturn and outmanouver 109 which was shoted down by Skalski.

[Kodoss]

I guess the only problem would be that people would instantly attempt to crash the bad aircraft to get a better one. :/ Stupid gamers.

Simple solution: If you crash too often (no enemy contact, no bullet holes) you only get bad planes. Why waste a good plane to a bad pilot?!:rolleyes:

[CaptainDoggles]

I think a performance variance included in the sim would be great.

...

I guess the only problem would be that people would instantly attempt to crash the bad aircraft to get a better one. :/ Stupid gamers.

They could only do that if they instantly knew they had a bad one. If done right it wouldn't be readily apparent.

[5./JG27.Farber]

Given the keys to CloDo... was the question I was asked.

Well I would grant the reds the 100 octane performance data. I'd give the 109 the factory data. I would certainly adjust the roll rate of the padal winged spitfire.

Folklore and stuff in books by any pilot would be pretty much out of the window. Sorry Notafinger... However I would include the percularities of certain aircraft, like the 109's port wing stalls first near the stall etc.

As for random degress of performance in an aircraft, I'd say no...




The table in the OP only includes TAS, ingame I only have IAS. How do i know if the 109 is fast enough at 5k? According to the graph released by B6 its too slow at around 5k by 30 or was it 50 kmh?

[camber]

No no no no no!
Accuracy over all else. Arcade players be darned.

Well that's simple to say. But once the "rivet counters" (I seem to have become one lately :)) have spent time analysing the historical record, then developed (valid) competing arguments which give a range of performance, what would you do? Pick your favorite rivet counter?

Given the keys to CloDo... was the question I was asked.

Well I would grant the reds the 100 octane performance data. I'd give the 109 the factory data. I would certainly adjust the roll rate of the padal winged spitfire.

Folklore and stuff in books by any pilot would be pretty much out of the window. Sorry Notafinger... However I would include the percularities of certain aircraft, like the 109's port wing stalls first near the stall etc.

As for random degress of performance in an aircraft, I'd say no...


I agree with you on speed (haven't looked at roll issues). Would you give the factory average spec for 109s (it is +/-5%) though? My analysis suggested that would be OK for 5000m but a bit optimistic for sea level (Not that you have to use that :))

I would think that period pilot reports would rank higher than folklore but lower than flight tests when considering historical sources.



The table in the OP only includes TAS, ingame I only have IAS. How do i know if the 109 is fast enough at 5k? According to the graph released by B6 its too slow at around 5k by 30 or was it 50 kmh?


I calculate TAS as 2% greater than IAS per 1000ft altitude using this link (http://www.csgnetwork.com/tasinfocalc.html), there may be a more accurate calculation out there.

I just did some altitude speed tests offline (beta patch), they are OK for 109 but a bit horrifying for the RAF as they are below the B6 patch curves. I tested for full Throttle height (above which boost declines at full throttle). My assumption was that top TAS should be around FTH.

109E4 (prop pitch control on)

FTH: 5000m (boost has dropped a bit to 1.32ata, declines rapidly above 5000m)

425kmh IAS@5000m = 569kmh TAS, exactly right for Messerchmitt official average spec.

Spit Ia

FTH = 16500 ft
at 6.25psi, 2750rpm (rad open) engine fails after about 3 minutes. Just enough time to get stable 245mph IAS (with 3000rpm couldn't get this alt without engine death)

245mph IAS@16500ft = 323mph TAS = 520 kmh TAS

Oh dear, this is under even B6 plot speed (560kmh TAS at 16500ft).

Spit IIa

FTH = 13500 ft (?!)
at 6.25psi, 2750rpm (rad open) engine fails after about 3 mins

260mph IAS@13500 = 328mph TAS = 528 kmh TAS

I really hope I making some kind of testing error here. Tried online and got same values. I wouldn't feel confident taking any Spit against 109s at alt with these values.

camber

[Kwiatek]

If you results are correct speed performacne of both Spitfire version is way off for sea level (low level) but also at higher alts. Actually in beta patch british fighters performance doesnt match even historical performacne at 87 Octan fuel. So just after betapatch these British fighters are way too slow.

I wonder what you get with Hurricane MK1 Rotol beacsue at sea level it is also much too slow comparing to RL data?

I wonder why 1C cant do it correctly? Even in old Il2 146 when i was making FM tuning for Ultr@pack i could achived very accurate results from 0 to 10 km in speed and climb for all these planes????

[robtek]

I believe there is a general error in the game engine with the calculation of the athmospheric density or something like that, causing the problems above 7000 m and MG is now trying to fix that with FM changes.

That will never work, imo

[6S.Manu]

I believe there is a general error in the game engine with the calculation of the athmospheric density or something like that, causing the problems above 7000 m and MG is now trying to fix that with FM changes.

That will never work, imo

This.

[Kwiatek]

I believe there is a general error in the game engine with the calculation of the athmospheric density or something like that, causing the problems above 7000 m and MG is now trying to fix that with FM changes.

That will never work, imo

If they cut sea level speed for british fighters (and now they are way too slow) it would affected also for speed at higher alts. It looks that most British fighters are too slow about 40 km/h at all alts - and thats only for 87 octan fuel performacne. So how it could work????


"Hurricane MK 1 Rotol

238 mph /383 kph at the deck at +6 1/2 boost ------ should be 262-265 mph /420-426 kph !!!!

So it is 24-27mph/ 38-43 kph too slow at + 6 1/2 boost power !!!!

There is no WEP - so no 100 octan fuel performacne - which should give ab. 25 mph/ 40 kph extra speed at low alts

Spitfire MK1a

255 mph/410 kph at the deck at 6 1/2 boost ---------should be 283 mph/455 kph !!!!

So it is 28 mph/45 kph too slow at 6 1/2 boost.

No 100 Octan fuel performance at all - boost cut out doesnt rise power at all.

Spitfire MK II

268 mph/431 kph at deck at 6 1/2 lbs
285 mph/458 kph at deck at 9 lbs ------ should be 286-290 mph so it is quite accurate result!!!!

No emergency take off power +12 lbs included."


and



109E4 (prop pitch control on)

FTH: 5000m (boost has dropped a bit to 1.32ata, declines rapidly above 5000m)

425kmh IAS@5000m = 569kmh TAS, exactly right for Messerchmitt official average spec.

Spit Ia

FTH = 16500 ft
at 6.25psi, 2750rpm (rad open) engine fails after about 3 minutes. Just enough time to get stable 245mph IAS (with 3000rpm couldn't get this alt without engine death)

245mph IAS@16500ft = 323mph TAS = 520 kmh TAS

Oh dear, this is under even B6 plot speed (560kmh TAS at 16500ft).

Spit IIa

FTH = 13500 ft (?!)
at 6.25psi, 2750rpm (rad open) engine fails after about 3 mins

260mph IAS@13500 = 328mph TAS = 528 kmh TAS

I really hope I making some kind of testing error here. Tried online and got same values. I wouldn't feel confident taking any Spit against 109s at alt with these values.

camber



For 109 speed curve is much more close to RL data ( RL 467-475 km/h at 1.3 Ata at the deck and 570 km/h at 5 km). 109 is only about 20 km/h too slow at low level and deck.

Il2 CLOD is successor of IL2 1946 if some things could be possible to achive in old Il2 i dont belive it is not possible to achive in CLOD.

[ATAG_Snapper]

If you results are correct speed performacne of both Spitfire version is way off for sea level (low level) but also at higher alts. Actually in beta patch british fighters performance doesnt match even historical performacne at 87 Octan fuel. So just after betapatch these British fighters are way too slow.

I wonder what you get with Hurricane MK1 Rotol beacsue at sea level it is also much too slow comparing to RL data?

I wonder why 1C cant do it correctly? Even in old Il2 146 when i was making FM tuning for Ultr@pack i could achived very accurate results from 0 to 10 km in speed and climb for all these planes????

These results correlate with what I and others have found. It was Camber's initial observations several weeks ago which led me to test the Ia and IIa both online and offline. The IIa actually has different performance curves online compared to offline. Online the IIa performance curve tails off significantly with altitude compared to its offline counterpart!

[5./JG27.Farber]

I believe there is a general error in the game engine with the calculation of the athmospheric density or something like that, causing the problems above 7000 m and MG is now trying to fix that with FM changes.

That will never work, imo

Yes I think its allot more complex than moving two points on a graph.

I wonder if they will bodge it?

[camber]

If you results are correct speed performacne of both Spitfire version is way off for sea level (low level) but also at higher alts. Actually in beta patch british fighters performance doesnt match even historical performacne at 87 Octan fuel. So just after betapatch these British fighters are way too slow.

I wonder what you get with Hurricane MK1 Rotol beacsue at sea level it is also much too slow comparing to RL data?

I wonder why 1C cant do it correctly? Even in old Il2 146 when i was making FM tuning for Ultr@pack i could achived very accurate results from 0 to 10 km in speed and climb for all these planes????

I actually just had a go with the rotol hurri offline, beta patch.

FTH 15500ft
2700 rpm +6.1psi
235mph@15500 ft = 305mph TAS

I rechecked the Spit I and Spit II again got exactly the same values before except I found out at 2700rpm the engines were fine and 2800rpm the engines blew. Speed didn't change though.

[Crumpp]

235mph

If it is indicated airspeed in a Hurricane you subtract 4 mph from your IAS to get CAS and 6 mph for compressibility effects to get 225 EAS.

225mph EAS * .869 = 195.525 KEAS

EAS * SMOE = TAS

195.525 KEAS * 1.27105 @ 15500 feet = 248.5KTAS

248.5KTAS * 1.15 = 285.8mph TAS

However that is all nonsense as the conditions in the summer of 1940 were not a standard day.

Your density altitude is actually much higher than standard in the game. That means you will see reduced Indicated airspeeds over the data converted to standard at the same altitude. Your TAS will be higher because the Standard Means Of Evaluation increases with altitude.

To calculate for the actual conditions in your game you need some atmospheric information:

Temperature
Pressure
density
dewpoint spread

At a minimum you can need pressure and temperature to approximate the density altitude.

You should be able to get both from aircraft cockpit instruments. Many airplanes have an OAT or outside temperature gauge and you have to set your altimeter to the pressure.

[Crumpp]

FTH 15500ft
2700 rpm +6.1psi
235mph@15500 ft = 305mph TAS



If that is standard day data, then it seems to give excellent agreement with measured data depending on the weight of the Hurricane in CLoD.

[Crumpp]

Spit Ia

FTH = 16500 ft
at 6.25psi, 2750rpm (rad open) engine fails after about 3 minutes. Just enough time to get stable 245mph IAS (with 3000rpm couldn't get this alt without engine death)

245mph IAS@16500ft = 323mph TAS = 520 kmh TAS

Oh dear, this is under even B6 plot speed (560kmh TAS at 16500ft).


What data are you looking at camber?

If it is this:

http://www.spitfireperformance.com/n3171.html

Then you are not at the same engine settings as this data. This data is 6.5lbs @ 3000 rpm at 16,500 feet.

Unfortunately we only have the one airplane and not Supermarines mean with a percentage variation.

If you look at this test:

Aeroplane and Armament Experimental Establishment
Boscombe Down
30 July 1940
Comparison of Performance of Rotol and DH Airscrews on Spitfire


Both the aircraft are similar externally and are fitted with bullet proof windscreen and armour plating over the tank, etc.

Aircraft R6774 is fitted with DH airscrew and N3171 with Rotol airscrew.

It will be noted that these aircraft are about 12 miles an hour down in speed against the previously tested K9793, but the relative comparison remains. This loss in speed is accounted for, by 6 miles an hour for the bullet proof windscreen and 6 miles an hour due to loss in engine power.

Level Speed miles per hour.


Aeroplane Altitude Feet


14000 16000 Max. speed 20000 22000
R6774 342 349 355 @ 17,800' 350 341
N3171 336 343 354 @ 18,900' 354 352



--------------------------------------------------------------------------------


The above tests were all carried out using 87 octane fuel with boost limited to +6.25 lbs./sq.in. Climb figures were achieved using the 2600 rpm 1/2 hour climb limit. By the Battle of Britain all operational squadrons had changed over to 100 octane fuel and the engine limits on the Spitfires had been increased to +12 lbs./sq.in. 3,000 rpm with 1/2 hour climb limit increased to 2850 - 3000 rpm. Royal Aircraft Establishment figures for a Spitfire I using +12 lbs/sq. in. boost are 314 mph at Sea Level and 359 mph at a full throttle height of 11,500 feet.



We don't have the entire report but we do have the poster's comments at the bottom. Throwing those out the window we get a little closer to our 2750 rpm.

BTW, running a propeller at a higher rpm on a hot day at high altitude does not mean the airplane will go faster. Usually it will go slower than it will at a lower rpm.

On that report, the data is only between 7% to 5% off from the reported figures at the lower rpm. We don't know the weights, so the data could be spot on or it might be off.

In order to make a definative statement we need:

1. Atmospheric conditions
2. Speed at same engine settings
3. weights of the aircraft

[Seadog]

If that is standard day data, then it seems to give excellent agreement with measured data depending on the weight of the Hurricane in CLoD.

Except that Full throttle = 3000 rpm and 6.25lb boost:

http://www.wwiiaircraftperformance.org/hurricane/l2026-level.jpg

[camber]

What data are you looking at camber?


The B6 data was that posted by B6 (1c representative) about the post-beta patch CloD performance in this thread (i.e. sim not historical data):

http://forum.1cpublishing.eu/showthread.php?t=31450


If it is this:

http://www.spitfireperformance.com/n3171.html

Then you are not at the same engine settings as this data. This data is 6.5lbs @ 3000 rpm at 16,500 feet.


Agreed on the rpm. However the boost in the posted link for N3171 is stated as +6 1/4 psi nominal, and during the top speed test table it is listed as +6.1psi at 16500ft. The CloD Merlin failed within minutes at rpm> 2700 and FTH, and max available boost at or just below FTH is +6.2psi for the SpitI (and Spit II). So 2700rpm, +6.2psi was tested as CloD max practical height performance(BTW 3000rpm at same boost did not indicate any speed increase in the moments before the engine failed, rad open)


On that report, the data is only between 7% to 5% off from the reported figures at the lower rpm. We don't know the weights, so the data could be spot on or it might be off.

In order to make a definative statement we need:

1. Atmospheric conditions
2. Speed at same engine settings
3. weights of the aircraft

I think an interesting issue is the difference in TAS we have calculated, me using a rather simple thumb rule (TAS = IAS + 2% increase per 1000ft), you with a more rigorous approach. Eg for Hurricane:

Rotol Hurri = 235mph IAS@15500 ft

My calculation (2% rough rule) gives 305mph TAS, your calc gives 286mph. Thanks for providing a more rigorous calculation.

I actually hadn't checked whether how the Hurri compares at height to the B6 data and RAE Hurri tests, I just did a quick offline Hurri sim test in response to a question from Kwiatek...sounds like from your analysis it is not too bad. Earlier I was referring to the Spit and 109 data which (for Spits) showed TAS at FTH being too low for both the B6 data (hence what 1c intended the patch to allow) and historical RAE tests. The 109 is pretty good at height according to my 2% rule calc (i.e about the average Messerchmitt guaranteed spec). It might drop under with your calc method, I guess an important consideration is what are the equations in the simulation of how IAS and TAS relate.

Cheers, camber

P.S I should note my IAS speeds at height are from offline, and Snapper has noted some oddities and discrepencies for the SpitII between online and offline

[Crumpp]

equations in the simulation

The equations in the sim should be the same.

The CloD Merlin failed within minutes at rpm> 2700 and FTH

What were your other settings? Radiators and how did you treat the engine before hand?

What rating did you climb and did you allow the temperature to recover after climbing?

Climbing is the hardest thing you do to an airplane engine.

Except that Full throttle = 3000 rpm and 6.25lb boost:


285 mph at 2700 vs 315mph at 3000rpm....

Do you understand the conversation Seadog? I really don't think so but rather feel the need to comment because you somehow believe I am a threat to your favorite gameshape.

My suggestion would be to learn about how aircraft perform and put your pointy tin foil hat aside.

[Seadog]

285 mph at 2700 vs 315mph at 3000rpm....

Do you understand the conversation Seadog? I really don't think so but rather feel the need to comment because you somehow believe I am a threat to your favorite gameshape.

My suggestion would be to learn about how aircraft perform and put your pointy tin foil hat aside.

A) the poster made a point of stating that higher RPM led to engine failure, but this was the rated RPM for full power and this needs to be addressed for the game to properly simulate Merlin III engined aircraft.

B) Boost at height is related to engine RPM and there's no way that 2700 rpm at an altitude/pressure altitude of more that 16500 ft would permit 6.25lb boost to be attained - another flaw in the simulation. I am rather shocked that you don't know that.

Maybe you should have considered these points.

I know you admire the RR Merlin very much but you need a better understanding of it's capabilities.

[camber]

The equations in the sim should be the same.

One certainly might hope so but perhaps not count on it


What were your other settings? Radiators and how did you treat the engine before hand?

Radiators fully open, I polished the engine and swapped the rubber hoses for braided stainless steel :)


What rating did you climb and did you allow the temperature to recover after climbing?

Climbing is the hardest thing you do to an airplane engine.


Climbed from sea level to FTH at 140mph IAS, full throttle, 6.2psi, 2700rpm. Full fuel and normal ammunition load. FTH@2700rpm detected via onset of boost drop from 6.2psi. Aircraft allowed to settle at close as possible to FTH@2700rpm and 0 fpm. Speed taken from guage in no cockpit view.

Your point is correct that cooling the engine (e.g by throttling back at FTH to give say 150mph IAS for a while, then accellerating to maximum speed) might make it possible to stay on 3000rpm for longer without engine failure. But 2700rpm to 3000 rpm at FTH gave no hint of speed increase prior to the engine failure.


Cheers, camber

[Robo.]

285 mph at 2700 vs 315mph at 3000rpm....

My suggestion would be to learn about how aircraft perform and put your pointy tin foil hat aside.

Crumpp please have a go yourself, I am looking forward for your tests at FTH at full power. ;)

[Crumpp]

Climbed from sea level to FTH at 140mph IAS, full throttle, 6.2psi, 2700rpm

That looks like a problem. According to the Operating Notes, Vy for the Spitfire Mk I is 185mph ASI below 12,000 feet, 179 mph ASI to 15,000 feet, and 169 mph ASI to 20,000 feet.

Climbing at such a reduced airspeed will limit the cooling of the engine at a very high manifold pressure and rpm.

If your oil temperature and coolant temperatures are high, you won't last as long at any overboosted condition.

Try climbing at the faster speed. You should get to altitude quicker and have a cooler engine.

But 2700rpm to 3000 rpm at FTH gave no hint of speed increase prior to the engine failure.


In reality it won't either so that actually sounds realistic. In fact, on a summer day, the aircraft will slow down instead of speeding up. That is why I was saying many folks will be mad if they realistically model density altitude effects.

Once the propeller tips begin to approach their mach limits, the ability of the propeller to make thrust diminishes. So you get less thrust the faster your propeller turns at high density altitudes.

[camber]

That looks like a problem. According to the Operating Notes, Vy for the Spitfire Mk I is 185mph ASI below 12,000 feet, 179 mph ASI to 15,000 feet, and 169 mph ASI to 20,000 feet.

Climbing at such a reduced airspeed will limit the cooling of the engine at a very high manifold pressure and rpm.

If your oil temperature and coolant temperatures are high, you won't last as long at any overboosted condition.

Try climbing at the faster speed. You should get to altitude quicker and have a cooler engine.


True for a real MkI, but remember we are talking about a CloD Spitfire with modelling issues.

I tried climbing at 170mph IAS to 16500ft, +6.2psi 2700 rpm
Oil temp at 16500 feet 93'C, coolant 107'C
Itunes playlist: Kim Wilde 1980's pop diva
Throttle back to +2psi 5 mins for cooling, Oil 91'C, coolant 100'C
Then 3000rpm +6.2psi for max speed test.
Itunes Song: Kim Wilde "Kids in America"

What do you get under similar conditions? I don't want to give away all the flight tests, we need to encourage a cadre of high alt flight testers for CloD to get some data variability :)

Cheers, camber

[Crumpp]

we need to encourage a cadre of high alt flight testers

When am I supposed to fit that in?

:grin:

[fruitbat]

True for a real MkI, but remember we are talking about a CloD Spitfire with modelling issues.

I tried climbing at 170mph IAS to 16500ft, +6.2psi 2700 rpm
Oil temp at 16500 feet 93'C, coolant 107'C
Itunes playlist: Kim Wilde 1980's pop diva
Throttle back to +2psi 5 mins for cooling, Oil 91'C, coolant 100'C
Then 3000rpm +6.2psi for max speed test.
Itunes Song: Kim Wilde "Kids in America"

What do you get under similar conditions? I don't want to give away all the flight tests, we need to encourage a cadre of high alt flight testers for CloD to get some data variability :)

Cheers, camber

Camber I see your problem.

Its a well known fact you will climb better with Elton John - Rocket Man.

Of course, you will bleed from your ears.....

[bongodriver]

Of course, you will bleed from your ears.....

And other places if Elton has his way......

[Crumpp]

rubber hoses for braided stainless steel

Bad idea in an airplane....

I have experienced a cut oil return line (low pressure thankfully) and had a hole in the intake manifold cut by braided stainless steel lines.

I got rid of every one. Braided stainless steel and airplane engines do not mix very well.

[5./JG27.Farber]

Hang on a minute... Was this thread not about the 109?

[notafinger!]

Hang on a minute... Was this thread not about the 109?

No, these are the 100 octane forums.

[ATAG_Snapper]

Bad idea in an airplane....

I have experienced a cut oil return line (low pressure thankfully) and had a hole in the intake manifold cut by braided stainless steel lines.

I got rid of every one. Braided stainless steel and airplane engines do not mix very well.

Nor Harleys!

Last year out for a ride I noticed my gas consumption radically increasing, plus my left leg suddenly feeling very cold. Pulled over and found 94 octane gas sprinkling down from under the gas tank and sizzling on the hot air-cooled V-Twin underneath. Fortunately closing the fuel petcock stopped the flow, but the nifty s/s braiding had worn through the fuel line it was covering leading to the carb. Loosened two hose clamps and one of my buds made a quick trip with the braided line to a nearby Canadian Tire for a plain rubber counterpart. The fix was quick, easy, and cheap in this case, but can't imagine the huge danger this would've been in an aircraft!

[5./JG27.Farber]

Same thing happened to me, fuel line split, half a tank rolled straight down one of the steepest hills in sheffield at night. I thought about lighting it to burn it off but decided that would be worse than gushing nine letres of Petrol down the hill... Unfortunatley the Kawasaki er5 doesnt have a stop on the fuel cock. -Only res and on!

They were not braided... I suppose better visual inspection is the lesson here... I also had to push all 100kilos of it up the rest of the hill with the aid of my drunken cousin who insisted the bike had to be straight instead of leaning slightly my way, so it was twice as hard and took twice as long...

[camber]

Hang on a minute... Was this thread not about the 109?

Yes it was, I cleverly managed to derail my own thread on historical 109 performance by posting CloD high alt flight tests of all aircraft. Then my flight tests contaminated another thread on turn rates with all the power of 100 octane :).

Then I managed to derail it again by making a joke about stainless steel hoses.

What you people don't seem to understand is that you should take everything I say about the 109 as gospel because unlike you, I own a real 109, have flight tested it and have the video. Sure it is a 109G, and must be Hartmann's old ride because it has his girlfriend's name on the side. But I am sure he took good care of it and always kept his braided stainless steel hoses clean :):

(Apologies I post this video anytime I feel I can get away with it):

http://www.youtube.com/watch?v=8aVsEwvjfNI

I have my own MkII Spit as well, 1C has failed to model the high altitude propellor falling off flight condition:

http://www.youtube.com/watch?v=a8q6g4n7tdg

camber