how was that patronising drivel?

that was just plain rude.

also on the ignore list, im ouita this conversation. leave to your 2 oversized ego's

I wish we were having this conversation in the pub, I woulda bashed you both out by now.

Oh crap, sorry......I somehow saw Crumpps avatar and your post, I honestly had no idea I replied to someone else, my most sincere appologies.....I think it's because it was quoting the same post by me.

Read macros reply to my post and learn how to actually process information.

:confused:

Youre confused?....ok I'll take you through it carefully

Kurfurst said of the Spit in his scenario 'can hardly turn at all'......but why would the aircraft suddenly not be able to turn any more?......it in fact will continue to turn quite happily, what it won't do is sustain speed.

As my 6 year old would say, I am confused on who is whose friend, LOL.

:wink:

:-P

:confused:

But your graph Crumpp bears little resemblance to the RAE chart. Your chart gives the 109 a better sustained capability whilst the RAE chart gives the Spitfire a better sustained turn performance ?

RAE Chart from AVIA 6/2394

http://i40.photobucket.com/albums/e2...109susturn.jpg

Crumpp chart:
http://imageshack.us/a/img228/1949/s...bf109e3sus.jpg

Dont see any parameters/conditions/assumptions used on your chart either Crumpp

Who is right RAE or Crumpp ?

Do some math....

The RAE chart is at 12,000 feet and was taken off one data point. It did puzzle me as our radius and other data aligns. It puzzled me until I stated getting into the details of the chart.

According to that chart, the Spitfire Mk 1 is capable of reaching 340mph (+) at 12,000 feet on 1050 bhp.

The RAE graph found in AVIA 6/2394 is a performance estimate from September 1940.


A flight report from March 1940 gives the power at 12,000 feet:

And lists the Vmax for the type as 326 mph TAS.

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

The AVIA 6/2394 does not fit the only +12lbs estimate we have for level speeds.

http://www.spitfireperformance.com/s...-rae-12lbs.jpg

This estimate shows 359mph TAS at 12,000 feet.

That is over a 5% error from the speed found in AVIA 6/2394. It would be unusual for such a large estimate error in an established design.

I don't know what Spitfire data they used but I suspect it was for an improved high altitude version as we saw before in a similar report previously posted on these forums in which you were involved in the discussion.

All that can be said is we don't know the details and the ones we do know, do not fit any existing service model at the time.

When we plug in the data from the Spitfire Mk I serving in the RAF during the BoB, we get a different result.

Another anomaly is the CLmax. In order to get a CLmax of 1.87 on the Spitfire, you have to drop the stall speed far below what the Spitfire POH list's to a scant 62 knots.

At the 76mph Vs (69mph IAS Vs + 7mph PEC) found in the POH, we get a CLmax of 1.69 which is far below the 1.87 Gates uses in the report.

I am pretty sure Gates was not using a standard Spitfire Mk I for his base data in the estimate. It does not align with one.


Calculate Sea level CL max:

CL = Lift/(dynamic pressure * Reference Area)
Dynamic Pressure = density ratio * Velocity^2 / 295

Dynamic pressure = (1 * 66^2)/295 = 14.76610169psf

CL = 6050lbs / (14.76610169psf * 242sqft) = 1.693067034

Lift = CLqS

Lift = 1.87 * 14.76610169psf * 242sqft = 6682 lbs of Lift generated.

"I don't know what Spitfire data they used but I suspect it was for an improved high altitude version as we saw before in a similar report previously posted on these forums in which you were involved in the discussion.

All that can be said is we don't know the details and the ones we do know, do not fit any existing service model at the time."

"Normal B.H.P 950/990 at Rated Altitude 12,250 ft '

Garbage ! you are confusing rated power at 2600RPM with maximum power at 3000RPM. Here are 2 inspection test certificates for 2 different Spitfire MKI's one with a Merlin II the other with Merkin III. As you can see Max power is 1030hp at 16,250ft. at 6.25lbs boost 3000RPM.

The RAE chart references 1050hp at 6.25lbs Boost 3000RPM at 12,000ft.

http://i40.photobucket.com/albums/e2...ps5d31181a.jpg

http://i40.photobucket.com/albums/e2...ps805b515b.jpg

You are again trying to change history. You cover up your case by a smokescreen of Mathematical verbiage. RAE calculated that the Spitfire MKI had better sustained turn performance than the BF109E3. Pretty much every other report technical and general from either side of the conflict say the same. You on the other hand construct a graph that clearly shows the opposite.

Find another single independent reference that proves the BF109E3/4 had better sustained turn performance than a Spitfire MKI.

Whilst you are at it show us what this Mythical improved high altitude version that I supposedly referred to in another report and how this is supposedly used in the RAE turn chart

And what do we see on the 109 data? Estimate on chart = 1,200 Bhp at 2,400 rpm 15,000 feet, TAS 340 mph + at 12,000 which Crumpp, conveniently has ignored, whereas the true output was about 960 ps 2,300 rpm at about 3,500 metres

http://www.wwiiaircraftperformance.o...oct40-pg22.jpg

So Gates was also using an unusually powerful 109 for the chart as well. I suspect it was probably an experimental high-altitude 109E.

Question is what data did Crumpp use to compile his chart? There's no engine rating shown, no take of weights, nor anything else to indicate on what basis Crumpp's "calculations" were made. For any proper analysis Crumpp's chart is totally useless.

The data is listed in the thread.

Here it is too, right off the spreadsheet:

Spitfire Mk I

Aircraft Data
weight 6050lbs
Power 990bhp
Level speed 247KEAS
Propeller efficiency 0.8
Wing area 242 sqft
wing efficiency 0.85
Dynamic pressure 206.8101695psf
Aspect Ratio 5.6
Mass 187.8881988 ft/s^2


Bf-109E-3

Aircraft Data
weight 5580lbs
Power 990bhp
Level speed 269KEAS
Propeller efficiency 0.85
Wing area 174.9 sqft
wing efficiency 0.85
Dynamic pressure 245.2915254
Aspect Ratio 5.77
Mass 173.2919255 ft/s^2

Again, it just calls into question the validity of the RAE estimate. I just figured it was a given the RAE would not have the best data on the German aircraft.

They did a lot of estimating off very few data points. The CLmax for both aircraft closely matches the full flaps CLmax and not clean configuration.

Well clearly you haven't read AVIA 6/2934 They had reasonable data on the aircraft in question. AVIA 6/2934 is based on actual flight test of a BF109E3 in RAF hands.

Here is AVIA 6/2934 summary of turn performance based on Flight tests and calculation :

http://i40.photobucket.com/albums/e2...ps5a547e44.jpg

So the RAE determined the opposite to you based on flight test and calculation.

To me it seems RAE determined something entirely different than Crumpp's calculation... (turns at and only at minimum turn radius vs. Crumpps calculations over the speed range)

The RAE chart on its own shows sustained G over the complete speed range at 12,000ft altitude.
Its the a similar but more detailed chart to Crumpps.

RAE's calculation also using estimated/guessworked stall speeds, Clmax and rather questionable power values for both the Spit and 109 (the latter probably understood with the effect of engine thrust). That's the problem with these charts in general - there's such a margin of error with the base values, that the results are all over the place. (estimated) Propeller effiency can vary results by 5-10% alone, drag values are unknown, the wing's oswald effiency factor is unknown (directly shifts the results, since its a multiplier in the equation), Cl max is unknown.

Just to make it clear I don't doubt the Spit had a sustained turn advantage at lower speeds, but OTOH I am pretty sure the situation reverses at higher speeds (for the 6 1/2 lbs version) at lower altitudes, since the 109E has both less drag and more power.

I am also curious about the effect of the two speed prop on turn capacity. Having 990 HP at the prop shaft is nice, but its all for naught if the two pitch prop can't properly convert it into thrust at turning speeds.

The RAE chart shows a Spitfire sustained turn advantage across the entire speed range from the Lift limit through to the max 1G sustained speed of around 340mph.

i.e. if the "Angle of straight climb" (Ps=0) for both the Spitfire and BF109 were overlayed on the same chart the Spitfire angle of straight climb would be above the 109 line from the Lift limit through to 1G Vmax. So at any speed in this range the Spit can sustain a higher G according to the RAE .... but not according to the Crumpp plot ... at any speed.

Both aircraft in this chart having similar values of 1g Vmax at the charted altitude.

There is no mention of prop type in the AVIA report for either the Spitfire or the 109. I take your point on propeller efficiency though ... that is touched on in another AVIA report (AVIA 6/13805) in which the RAE believe the 109 and Spit prop efficiency was essentially the same at 10,000ft with the 109 around 3% better at 15,000ft.... though with caveats.

http://i40.photobucket.com/albums/e2...psdc0a9590.jpg

Just one observation. Janes gives the Merlin III with 100 octane as 1,310 hp at 9,000 ft, not 990 hp, which would make a difference

Interesting how the Bf 109E-3 loading chart http://www.wwiiaircraftperformance.o...ladeplanes.jpg shows the weights as 2,608 kg (5,749 lbs) fully loaded for combat while, without ammunition for training flights, the weight is 2,532kg (5,582 lbs)...

All that extra power from 12 fewer litres. According to some of the logic here I conclude, mathematically, that the DB601 was rubbish.

Well good for you, now would you kindly push that thing you call a flight stick forward. :p

I got the weights from several flight test but did not have a ladeplan. The weight I used leaves out the pilot.

I fixed it and it narrows the gap but does not eliminate it.

The RAE chart uses CLmax neither airplane can attain in clean configuration by any calculation or measurement, including the RAE's. Read the report you claim I have not!

In fact, the CLmax comes very close to matching full flaps for both aircraft.

I don't know about rubbish, that is a bit strong, but its worth remembering that it was soon changed for the DB 605 and the Germans wouldn't have done that without a reason. I can only assume that it lacked development potential

Why on earth would you leave out the pilot?

Seriously are you going to redo the numbers with the extra Merlin power, 30% will make a huge difference.

Crumpp has to be carefull...if he starts using realistic figures the results won't come out as he intends.

I guess RAE were clueless ... and you have superior knowledge Crumpp... trouble is your graph reflects the opposite of pretty much every known record,chart,computation or actual flight test or pilots account of the facts !

http://i40.photobucket.com/albums/e2...ps42dd3e5b.jpg

One more from the RAE clearly showing better turn performance of the Spitfire in all regimes.

It is not a more detailed chart. It is the same thing.

Only difference is the CLmax estimates. The RAE used a trailing rake to measure speed.

Those are very accurate when properly operated but are complex to operate. They measured the CLmax in flight. I see a problem with operating such a system at the edge of the envelope trying to stall a high performance fighter.

As for the weight of the Bf-109, my original estimate just used the one the RAE used for the test. Using the ladeplan does not change the relative performance significantly.

http://kurfurst.org/Tactical_trials/...ls/Morgan.html

My calculated CLmax agrees with the RAE measurements for the Bf-109.

Speeds Dynamic pressure CL
82 22.79322034 1.433906325


http://imageshack.us/a/img705/576/109estallandslats.jpg

My Spitfire CLmax agrees with the NACA findings and the calculations were made using standard data on the type with the weights and stall speed listed in the Operating Notes.

That was my first thought. Gates was using high angle of attack theory to determine turn performance. High angle of attack theory is good for estimation but has to be based on measured data otherwise it is a complete crapshoot and guesswork.

The stumbling block to the assumption that Gates used high angle of attack theory is the fact he clearly list's the 1G stall CLmax for both aircraft.

That listed CLmax is clearly labeled on the chart as "assumed values of CLmax":

Spitfire 1G CLmax = 1.87

Bf-109E-3 1G CLmax = 1.95

The only way either aircraft can achieve such a CLmax at 1G is in landing configuration with full flaps and gear down.

The CLmax Gates used matches both aircraft in landing configuration.

It is definate proof Gates used the landing configuration CLmax for his estimate.

Give the guy a chance, he said he would

Explain the "assumed values for CLmax at 1G" listed on the chart, Ivan??

I am listening....

Here is the mathmatical proof it is not correct for a clean configuration fighter:

Calculate Sea level CL max:

CL = Lift/(dynamic pressure * Reference Area)
Dynamic Pressure = density ratio * Velocity^2 / 295

Dynamic pressure = (1 * 66^2)/295 = 14.76610169psf

CL = 6050lbs / (14.76610169psf * 242sqft) = 1.693067034

Lift = CLqS

Lift = 1.87 * 14.76610169psf * 242sqft = 6682 lbs of Lift generated.

Hi crumpp, I've no issue with the math. Frankly I'm not scooled up in the formulae to critique it anyways. My interest is more as a historian, rather than engineer.

Can you advise why the Merlin power assumption is around 990bhp? And, when you use, say the Merlin 3, the auto prop and/or the 100 octanes, how do the graphs look?

Sorry if this creates loads of work....

With landing gear and flaps down......

Crummp, when quoting other people in the thread, please could you leave in the name of the person you're quoting as above? Quoting people without reference to who it is makes following the conversation very difficult.

Many thanks. :)

At 300MPH?

No problem at all. In fact I am going to clean up the sheet and post it so others can use it. It just runs the math for the conditions given.

I wish I was more computer savvy to make it more user friendly. Perhaps some in the community can improve upon it.

The 990 hp comes directly from the RAE.

Once I get good engine data on 100 Octane, I will do the estimate.

On these charts the data does not line up. The FTH do not even come close to assume RAM effect.

Level speed - FTH MS Gear = 11,000 ft

http://www.spitfireperformance.com/s...-rae-12lbs.jpg

Engine power estimate at Vmax (RAM effect) shows a FTH MS Gear = 8,000 ft

http://www.spitfireperformance.com/merlin3curve.jpg

Not saying the data is bad, just that this engine does not match this airplane. We need to find the same engine in the same airplane to get good data points.

Exactly....

Once again, explain the assumed values of CLmax on the RAE chart. I am listening.

Sure thing.

Thanks. I think this would be a good idea.
At least then we are all able to work to the same assumptions and review each others work. It's be good to see how the manipulation of one or more of the variables influences tge overall outputs.

Crummp, when the RAE refer to "normal bhp", do you know what the term "normal" refers to. Are there other bhp values which might be arrived at which are outside of that description?

Uhmm... the DB 605 is the same thing as the 601, but with "bored-up" cylinders... which had a larger diameter by a mighty [i]4 milimeter (0,154 inch for you guys).

The RAE shows better turn radius in this chart. The Spitfire always has a better turn radius than the Bf-109.

Radius being just one parameter of turn performance and not the most important either.

Not specifically. It appears to be RAM power because the chart list's power in flight.

Exactly, once the parameters are input, the math does it's magic.

Clmax is also depend of engine power. Prop wash adds considerable lift due to the higher speed of airflow.

Looking RAE turn charts for 109 and Spitfire there is discribtion:
" Assumed values for Clmax at full throttle ".

So Clmax in RAE charts is not for landing configuration or stall speed ( engine idle) but assumed for full engine power which of course is needed in sustained turn rate.

I'm not Ivan but they are obviously power on clmax.

Edit: Kwiatek is right, it is stated on the chart in plain text.

Flaps... ;)

True, if the aircraft are BOTH at the same speed (according to that chart) , the spitfire will have less distance to travel, and thus will turn faster, in every case.

I think I can convert the figures to turn rate fairly easily... Then we can see, using that very ddata, the combinations of speeds at which the two have varying turn speeds right?
See here, http://s13.postimage.org/4fo4e806f/turns_comparison.jpg

According to that, Provided the sptfire remains between 200kph and 370kph TAS, the 109 can never out turn it.

Wow....maths really is magic........it made Crumpp dissapear.

"Normal" shld stand for standard atmospheric value. The HP being a function of the air density, the Power have to be converted to the reference to be absolutely rigorous.

Note that standards varies (and still does) from one country to another.

ISO being 0°C and 1013mbar - CFM around 15°C etc..

Note also that if this is the case, there might be some error in the the conversion.

They are not at the same speed or angle of bank!

They don't match CLmax power on for either type. In otherwords, a bad assumption.

http://kurfurst.org/Tactical_trials/...ls/Morgan.html

I think you are right.

Doesn't matter if they are not at the same angle of bank, it's almost entirely the point that the spitfire was able to maintain level and sustained turns at a higher angle of bank than the 109.....kinda the key to a tighter turn don't you think? and in any case the Spit is achieving the tighter turn at higher speed than the 109 too.


I'd still rather accept the professionals theory on it opposed to yours....no offence.


Not sure why you quoted a snippet from a 'stalling' Cl max trial.

So while Crumpp is prepared to say that maths has all the answers compromises, such as leaving out the pilot and reducing the weight of an aircraft is okay - especially if it favours one type in particular over another. "I fixed it and it narrows the gap" but no explanation as to how this was done. Instead we are told to have faith in Crumpp's genius because he knows better than everyone else, as per usual.

Yep, one of the main flaws of Crumpps beloved maths, put garbage in and get more garbage back.

http://i40.photobucket.com/albums/e2...ps42dd3e5b.jpg

Er the chart above also shows Sustained G for any given IAS....at pretty much any IAS the Spitfire can sustain somewhere around 0.5G more than the BF109 ..... (not hard to determine turn rate here either)

The Blue RAE chart (from the same document) also shows sustained G, Turn times for 360 and also provides a means to determine Ps for bleeding turns ..... So we have turn radius, turn rate, sustained G (Ps=0) and a means to determine -Ve Ps values for energy bleed .... what more is there to turn performance ...... give us a break !

So far you have admitted to a weight error in your calculation. We know you made an error on the Spitfire power as well using 950/990BHP whilst RAE used 1050Hp at 12,500ft .... and we also know that a Merlin II power rating at Combat power was 1030hp at 16,500ft as detailed in the 2 seperate Inspection and test certificates.... shown earlier. And in Post 209 with respect Spitfire BHP you said "I suspect it was for an improved high altitude version".... when we know it wasn't and that RAE used standard Combat Power ratings.

Are you saying that, because we don;t know the AoB, we cannot therefore assume that their rotational velocity is equivalent - because the air passing over the indicator would not be equally displaced with respect to each aircraft's flight path?

If so, then yes, you're right I suppose.
Rotational velocity is dependant on more that simply airspeed and turn radius.. it needs "ground speed", essentially - which is the "real" speed around the spatial unit that is the turn.
Can we make any assumptions about likely AoB? The graph indicates that the turn is level (horizontally in each case). Do we know what the AoB differential is likely to be for each aircraft in each case? (then we can work out the proportion of airspeed that is in the horizontal plane).

Now lets look at this Clmax discussion which Crumpp claims the RAE cocked up. Lets look at some other peoples estimates for Spitfire Clmax values.

How about we start with NACA ... we will use that very same report Crumpp that you are so smitten with that you used in setting up the "Spitfire Dangerous Stability thread". Here is NACA's estimate on Clmax

http://i40.photobucket.com/albums/e2...ps0dfde387.jpg

So at Cruise power (3.75lbs boost 2650RPM) in clean configuration they come up with 1.68 (Recalling that the RAE plot is based on +6.25Lbs/3000RPM)


Then lets look at the RAE document they wrote in response to the NACA report:

http://i40.photobucket.com/albums/e2...psa488cccd.jpg

Interestingly the RAE methodolgy is slightly different to NACA's (Trailing versus Pole with swivel head) the RAE came up with Clmax on the glide (power off) of 1.36 and at max power of 1.89. The RAE Blue Turn plot uses a Clmax value under full power of 1.87

Of course we know the NACA report was based on a Spitfire MKVA so there will be some variance to the numbers of a Spitfire MKI but it does give some validation of the RAE determined Clmax under power values.

The NACA Spitfire MKVA document was good enough for you Crumpp in the stability argument regarding the MKI so I assume its an acceptable reference in this discussion ?

That is correct.

Why don't you do the math IvanK? You have a better idea of how to interpret aircraft data. That is not being patronizing, it is just a fact. You can set emotion aside and let numbers fall where they may....

If you do the math, you will find the values for CLmax align with the NACA's!!

Spitfire Mk I:

Speeds Dynamic pressure CL
66 14.76610169 1.693067034

http://imageshack.us/a/img716/1508/n...ps0dfde387.jpg


Once more, the RAE admits that operating a trailing static head is difficult as best. Do you know what you have to do? When installed, you have a tangle of tubes in the cockpit that the pilot must pinch off with an airtight seal on the correct lines at the right time. It is hard enough in cruise flight and would be extremely difficult to do accurately in a high performance fighter at the stall point.

That is why they labeled the values as "assumed values of CLmax".

http://imageshack.us/a/img571/9113/r...psa488cccd.jpg

Because of the difficulty in obtaining accurate measurements under certain conditions of flight.....

See above.

Glad you brought up all these points. You read my mind. .

You can use the NACA's values for some things on the Spitfire Mk V. The airfoil is the same. Airfoil selection is what determines Coefficient of lift.

If I would have posted it, some people would have just attacked it was from a different variant without understanding what is comparible and what is not.

Let me guess here.

The 'math' (or 'maths' as it's referred to over here) according to Crummp, shows something adverse to the documented real life performance of the Supermarine Spitfire relative to the performance of the Bf109.

There is a distinct pattern developing here.

I find it surprising that a man who purports to concern himself with the performance of 'real aircraft', does not spend his time debating these issues on a more appropriate forum involving comparisons between 'real world' aircraft.

Why would such an expert in his field waste his time on a forum geared to the analysis of a Battle of Britain based computer game? With most of his efforts geared toward the discrediting of the Supermarine Spitfire relative to the Messerschmidt Bf109?

It's a mystery to me, but maybe a psychologist could write a thesis.

:rolleyes:

It is not documented real life performance.....

It is calculated from a single data point with assumed values for CLmax.

That single data point was measured from a trailing static head.

What do you think the spreadsheet is??? Try the same the exact thing...calculated performance from data.

I just have the advantage of being able to use Mtt data, Supermarine, and NACA data that did not exist in 1940.

Uhm, the weight Crumpp used for the Spitfire I doesn't include the weight of armor either. So how this - marginal - weight difference favours one type over the other, Sherlock?

I see. Crumpp understands the formulae behind calculating turn radii and time, you do not, and somehow he is to be blamed for your ignorance? Or maybe it is his fault that after your never ceasing personal attacks, he is not particularly inclined to bother to explain it to you? :D

Crumpp
You are reading something into the paper which isn't there and as a result are making an incorrect assumption.

You are right in some of what you say but have ignored other parts of the quote. The paragraph can be summerised as follows

a) An accurate calculation of the turn performance is dependent on an accurate measure of the CL max in level flight
b) The only way that the CLmax can be accurately measured is the use of the trailing static head.
c) It is difficult to do (this is the part which you highlight)
d) Despite it being difficult it has been successfully done on both the Spitfire and Me109
e) That the method used by the NACA is not as reliable and gave a misleading result

By ignoring the other relevent parts your assumption that the RAE had to calculate the results because they couldn't measure the CL max is fundamentally flawed.

Its because they were able to get an accurate measure of the CL max in a glide and max throttle that an accurate calculation of turn performance was possible

I should add that the RAE did exactly the same with the Me109 so these are by far the best calculations around.

No, it's correct, RAE admits that it has estimated Bf 109 Clmax values from earlier Spitfire flights, and did not measure them.

The " stall boundary " depends on an estimate of CL max at full throttle. In the case of the Spitfire this has been measured in flight, while the Me.109 figures were based on the Spitfire results; tables of the assumed values of CL max are given in Fig. 17. CL max falls off as g is increased, because the stalling speed increases as g gets larger, thus lessening the slipstream effect.

In contrast, RAE only measured Clmax in throttled back conditions:

Only one flight was made, as operating a suspended static head from a single-seater aircraft with a rather cramped cockpit is difficult.[b] Stalling speeds with engine throttled right back were measured/b] with flaps and undercarriage up and down, and the speed at which the slots opened were also noted ; in every case both slots opened almost simultaneously.

http://kurfurst.org/Tactical_trials/...ls/Morgan.html

Nope. What RAE did can be best described as a reasonably close estimate based on guessworked Clmax, with wrong weight, and with wrong power. REA did not measure full throttle Clmax on the 109, they have estimated that from results with the Spitfire... so who's quoting out of context now, David?

The most accurate calculations for the Me 109 turn capability are those done by Messerschmitt A.G., for obvious reasons.

This paper clearly states that these measurements had been successfully done on the Me109. and it is clear that they had been measured on the Spitfire, Me109, Buffalo and Whirlwind.


So you agree that they were measured

Quote:

Stalling speeds with engine throttled right back were measured/b] with flaps and undercarriage up and down, and the speed at which the slots opened were also noted ; in every case both slots opened almost simultaneously.

And you agree that they were measured in landing configuration (flaps and gear down), plus gliding config (with flaps and gear up).

It should be noted that this section in the paper is titled
Stalling Tests 4.4 4.41 determination of CL max
Would you really expect them to comment on the CL max at full throttle during stalling tests?

However, you are corect when you say that the CL max at full throttle was based on the SPit figures but the RAE did have the accurate figs on the Stall and Gliding configs which is half the battle so would be a good estimate

Let me reword this for you
What RAE did can be best described as a close estimate of CL max at full throttle based on known Clmax for Gliding config.

I would say both of us missed something. However Crumpp when commenting on the RAE reply on the NACA tests missed a heck of a lot.

One obvious point which no one including me has mentioned, is that the RAE did have the 109. If their calculations said that one was better than the other at something, they had the aircraft to test the results. A luxury that we would love to have

PS - By the way, I have no problem you using my real name but can I ask what yours is?

And we have 70 years of data including classified documents from the people who built, designed, and flew the airplane in service.

Sorry, but we have the information advantage.

Are you saying that having the real aircraft, most up to date test facilities at the time, the only trained test pilots in the world (at the time) is not an advantage when testing theory.

There is a reason why the premier Aviation University in the UK is at Cranfield (not Cambridge who do not teach Aeronautical engineering or theory) its because they have their own test flight of aircraft often passed down from the RAF research establishments.
You should tell them they don't need the aircraft, it would save them a ton of money

That is a good point. We are talking about the test pilots who felt the Bf-109 was "embarrassed" by the slats opening in the turn.

I would not be surprised if the pilots did not operate the propeller at its most efficient point at the single data point the RAE used. That would throw off all of Gates assumption for the entire envelope.

In order to reproduce the RAE results, I have to drop the propeller efficiency to below average and assume VDM could not properly design a propeller.

:rolleyes:

It is the ones from Mtt that the RAE did not have access too. Germany was at war with England at the time so they were not exactly sharing information.

Instead, a pilot with little experience with a selectable pitch propeller had to go up and operate it to record data using a very difficult method of gathering airspeed data.

My Spitfire analysis is in agreement with the RAE's analysis.

The relative performance is not in agreement, but that has to do with Bf-109 performance and not the Spitfire's.

It's great that some of the information survived all these years, I've often wondered. Here in the States much of our early mechanical history, can be found in the library of Congress.

You can find all the patent information and applications in the National Archives. The Smithsonian has a bunch too.

Even foreign patents, I got all of BMW and Focke Wulfs on one of my visits.

So we can all look forward to you sharing this data so we can all draw our own conclusions? or are we just going to get your assurance you've seen it and done the maths and we can take your word for it?

As it happens yes they are. The UK had the first and at that time only test pilot training school in the world. As for being embarrased yes the Me109E was embarased by the way the slots opened, which no doubt was why they were redesigned for the Me109F. Unless you have a better reason for the redesign.

As for you having to drop the propeller efficiency to get the same results, working on the basis that you are not a trained test pilot then I can only assume that your model is wrong. I know you believe that the test pilots are not important but if I had to pick between their hard earned experience and training, backed up be the science of the day and access to the real aircraft, against your maths and how you read documents, I would go for the experts.

The title of the thread is:

Spit/109 sea level speed comparisons in 1.08 beta patch

So, we know that all aircraft are two slow, surely we just need a general consensus of which top speeds are correct given the fact that:

• 109 speed tests are not full throttle, 1.3 Ata is the maximum recorded/logged
• Aircraft have a gate system for more power
• speeds are slightly different on multiple tests
• Specific engines

So from this can we just agree on some numbers to submitted? :confused:

Crumpp,

You said:

"That is a good point. We are talking about the test pilots who felt the Bf-109 was "embarrassed" by the slats opening in the turn.

I would not be surprised if the pilots did not operate the propeller at its most efficient point at the single data point the RAE used. That would throw off all of Gates assumption for the entire envelope.

In order to reproduce the RAE results, I have to drop the propeller efficiency to below average and assume VDM could not properly design a propeller".

Given what Rall said below, would you not say that the "embarassed" remark was fair comment? If an event and effect designed for taking off and landing happens in the middle of fast air combat with no warning, when you do not intend it to happen, it is not a good thing is it? Esp if the slats do not function in an even way as per the design function. I would have thought that this effect should be part of the CloD FM. Thoughts?

Talisman

Me 109 E:
"And there I discovered the first thing you have to consider in a 109. The 109 had slots. The slot had a purpose to increase the lift during takeoff and landing. In the air automatically it's pressed to the main wing. And if you turn very roughly you got a chance, it's just by power, the wing, the forewing, comes out a little bit, and you snap. This happened to me. I released the stick immediately and it was ok then. "
- Major Gunther Rall in April 1943. German fighter ace, NATO general, Commander of the German Air Force. 275 victories. Source: Lecture by general Rall.

Me 109 E/F/G: - The plane had these wing slats and you mentioned they pop open uneven?
"Two meter slots on fore wings. The reason was to increase the lift during low speed take off and landing. To reduce the length of runway you need. In the air, if you make rough turns, just by gravity, the outer slot might get out. You can correct it immediately by release of stick, you know? Only little bit, psssssssht, its in, then its gone. You have to know that. And if you know it, you prevent it."
- Major Gunther Rall. German fighter ace, NATO general, Commander of the German Air Force. 275 victories. Source: Lecture by general Rall.

Its only fair to point out that problems with automatic leading edge slots that opened suddenly, were not unique to the Me109 at this time . The Westland Whirlwind also had the same issue but the squadrons decided in most (maybe all) cases to lock them so they wouldn't come out and live with the extra landing speed.

The Luftwaffe with the greater emphasis on these devices changed the design on the Me109F so they opened gradually. Kurfurst knows more than me about this but I think thats the basic situation.

This is not correct. They hve always open gradully. The diff in pressure makes them open as a function of it. It's a suction effect. The more, the wider ( humm.... stay focused.. )

The prob with the wider LE was IMOHO with the prop wash that in certain situation (yaw) prevented one slat to fully open. Having yaw angle is fairly comune during a DF unless you stay focused on your slip angle.

~S!

This is not correct, when the aircraft is pulling tight turns the g load on the slats makes them snap open, they are designed only to open gently at slow speeds for landing and take off.

The leading edge slats of the 109 work through air pressure distribution and this is depending on the angle of attack. The slats deploy gradually over a small range of the angle of attack, making it possible for them to snap open in abrupt manoeuvres, but they can also be made deploy gradually when increasing angle of attack gently.

The leading edge slats were reworked with the F series in that their span was reduced and the mechanism simplified. I don't think the deployment was changed a lot.

In my mind Kurfurst is the person for this, but what isn't in question is that they were redesigned for the 109F

No.

Here is handley page automatic slats in operation on my old airplane:

http://www.youtube.com/watch?v=-vbqgfjyW2Q

Unless they are new to you, the slats are nothing of note as far as piloting goes.

What do for the airplane is outstanding. You can pull some insane body angles with them.

Here is another video I made on the way to work. It was beautiful day to fly.

http://www.youtube.com/watch?v=UdgohV4gpXE

Pilot notes to a whole new level

When the Whirlwind's slats were tested at the A&AEE, it was found that when the slats were locked shut the take-off and landing characteristics remained the same, while the aircraft was more pleasant to fly at speeds during which the slats were normally open:
http://i91.photobucket.com/albums/k3...psbaca5f5f.jpg

http://i91.photobucket.com/albums/k3...ps6824eb2e.jpg

Crumpp, you need to take some drawings lessons :rolleyes:

It was cool to fly over that pretty countryside though...Crumpp what engine, a Lycoming?

I prefer this one, showing the glorious NZ countryside ;)

http://www.youtube.com/watch?v=yEWKC6cX2o8

You went through all that trouble instead of just showing me a scan of a pilot's license? the aircraft in the first video is not pulling high G so no wonder the slats are quite gentle.

Since you asked, yes intro flights are probably much more expensive in the UK than in the US, if you want to fly with me in a Stearman it will cost about £360 per hour, I don't remember what we charge for the 152's or warriors but it's around £150 per hour.

Heres the vid of me and fruitbat in a Stearman taken from that GoPro camera on my head in my avatar pic, check 14:30 for the 'hello Crumpp' and 17:30 for some basic aero's.

http://www.youtube.com/watch?v=oq4Ro...&feature=g-upl

Heres a vid of me flying the Learjet, 2008 fresh back from Dallas and doing my 6 cirquits to finish the type rating.

http://www.youtube.com/watch?v=Ud2Rb...&feature=g-upl

Very cool. Here's me and Riley squished in a Spit cockpit.....


http://www.youtube.com/watch?v=IZUZrruIAB8&sns=em

Sigh........sayin' nuffin.

Thanks for this

You're welcome - That comes from Victor Bingham's book on the Whirlwind
http://www.amazon.com/Whirlwind-West.../dp/1853100048

There is a reason why I am not a commercial artist, LOL.

Here is picture of my hanger, these are my planes....sole ownership....

Means you are alone on the bills too! ;)

http://imageshack.us/a/img198/2444/thehanger.jpg

Both are fully aerobatic but the Thorp is not a good platform for it. It is too slick and you really have to pay attention to your speeds when you point the nose down.

The Thorp is a good cheap, fast, and fun to fly cross country machine. It has a Lycoming O-360 with a Hartzell CSP. It is IFR, four place, and a traveling machine.

The Extra 300 is my sky cutter. It has a Lycoming IO-540 with an MT propeller.

Back to the thread....

Looking at all the data and trying to pick averages staying away from either extreme using both Supermarines and Mtt data......

This is the relative turn performance of these two aircraft taking as much data from the Operating Notes and Flugzeug Handbuch.

http://imageshack.us/a/img62/1949/sp...bf109e3sus.jpg

Here is a Rate of Turn comparison. Rate of turn is the most important aspect of turn performance as it represents how fast the aircraft can swing its guns thru the compass to bear on a target.

http://imageshack.us/a/img402/8112/rateofturn.jpg

Hope it helps!

There's some info on the 109 slats here http://109lair.hobbyvista.com/index1024.htm apparently the Fs still used the swing arm assembly of the E to actuate the slats, while the G series used a simplified roller track.

If you pull hard they will open with a loud bang but you don't even feel it on the stick.

You feel it most when you slowly change angle of attack.

The graphs having different scales makes it very hard to compare
http://www.gqth.info/0.jpghttp://www.gqth.info/7.jpghttp://www.gqth.info/8.jpghttp://www.gqth.info/9.jpghttp://www.ymeu.info/test5.jpg

Which Graphs?

What is the input data for your calculation?
- clmax (or stall speeds used + source)
- cdo (or power output, boost, rpm and speed + source)
- weight (source)
- assumed wing efficiency
- assumed prop efficiency

I would think the relation is about OK, but both planes are turning too fast and I also think that the high speed relation is a bit off.

Crumpp..Nice barn! but too small:-P

LOL, Yes it is and now I need a bigger one!

I don't have everything to do with WWII Aviation Nztyphoon.

Never claimed too but I do sit on the Board of Directors for a warbird restoration company.

Try spending a month looking for a waffengeber for a month and see if you don't learn something.

The airplanes are at sea level. Of course they are turning too fast....

Density effects will increase velocity, widen the radius, and increase the rate of turn. The engine power will also change with supercharger characteristics.

As for the high speed relation, anytime the aircraft has more excess thrust it will have a better turn rate as it can sustain more angle of bank at velocity.

The relationship is correct.

Considering the shape of the building and the powers of Google earth, it's for the best that you removed it.

Planes at sea level still turn as physics determine, not "of course too fast". If you posted your input data as requested, I could easily check if there's anything I'd disagree with.I could easily see that if you posted requested input data. The way it looks from here, you chose 285 mph for the Spitfire and 500 km/h for the 109 - which leaves me to wonder: Do you know of a lower sea level top speed for the Spitfire and do you know of a higher sea level top speed for the 109? Just asking, because I don't.

Yes they do and the formula's are all standard BGS for calculating aircraft performance.

They are same ones found in Perkins & Hage, Aerodynamics for Naval Aviators, Flight Mechanics, and Flight Theory and Aerodynamics.

You can argue with the authors of these books....

http://www.amazon.com/Mechanics-Flig.../dp/0470539755

http://www.amazon.com/Flight-Theory-...d+aerodynamics

http://www.amazon.com/Airplane-Perfo...ty+and+control

http://www.amazon.com/Aerodynamics-N...naval+aviators

The formulas are correct and the performance agrees with generic turn performance charts used in aircraft flight planning.

Input the correct parameters for wing area, power, aspect ratio, CLmax, and the formulas produce the results.

It is that simple.