I know that there no Boost button but under a FM coding point of view the boost behavior is equal to WEP.

That´s because you should make overheating and damage for it so the best way is implement it in the code as is done with WEP.

speaking tolerances..., in piston engines, I learned while attending a college in auto mechanics.. and engine rebuilding, that the tolerance for engine pistons in cylinders was purposely set a bit loose like .004 of an inch for faster break ins for engines that needed less break in times from the factory... , though you could set the tolerance down to .003 inch clearance of the pistons and cylinder for a much tighter fit, but slower break in times..

I would bore the cylinder and put a .003 inch clearance in the cylinder of v8 engines.
I also cut valves, rods, etc, on machining equipment.

Taking into account this was a long time ago in engines from the 1960's. the engine parts from the 1930's and 40's were still much older and had much different metal properties that the engines I worked on... and now they are completely different metal properties and break in periods..

the differences are the metals, and cast and forged engine components.. and the rings are totally different too... The oils were absolutely different back then, they were non detergent oils...

I was thinking the tolerances must have been much looser, as they really didn't have time to run long break ins to get performance.

The altitude difference and the condensation from going up and coming down in altitude is considerable and must have introduced a lot more water into the engines and oil, from more open breathing designs of engines...

The condensation buildup or moisture in aircraft (of any age) is significant from the changes in altitude and humidity, inside and outside of aircraft, and even more so when pressurized. Those engines must have been through hell to go into war when new, and no time to break in parts..

I could see how there could be large differences in the performance of the same type aircraft... as the first few hours of engine running made a lot of difference in the life of the aircraft parts.. so a 50-100 kmh difference makes sense..

When they say "boost" they just mean manifold pressure i.e. the throttle setting. The term doesn't always refer to any kind of emergency power. The overheating behaviour doesn't necessarily correspond between the aircraft capable of operating at +12lb/sq. in. and previous variants because different fuels were used. What was previously unsafe using 87 octane fuel would be achievable for limited periods and what was previously a 5 minute limit might then be a 15 minute limit, etc. Likewise there might be no changes to some of the operating limits. The devil is in the details. It's a struggle to find all the details because amendments to RAF Pilots' Notes and other such documents were often pasted on or clipped in as loose paper, and we usually only have scans or facsimiles of full editions to refer to.

Klem, I agree totally.

So to summarise as I understand it, we currently have a Spit I that has low alt performance about right for boost controlled at +4 psi (although the gauge reads +6 1/4 psi, the correct boost setpoint for 87 octane). The new plots suggest that this performance might be degraded in the patch to about equivalent to if the boost controller setpoint was +2 1/4 psi. Of course this leaves aside that frontline BoB Spit Is had 100 octane and a modified boost control cutout that increased the boost setpoint to +12 psi, and we don't know if the devs have any plans to fix that.

B6 if this is correct, I don't think the Spit I will be useable in MP, it is almost unusable now.

Wouldn't it be cool if the Spit I and Hurricane boost cutout actually worked? Incidently this would tell us the octane number of the fuel in those virtual tanks.

If they are unmodified and running 87, pulling the cutout at full throttle on the deck would give an instant +17psi boost. The engine would make horrible noises, lose power and become damaged in short order. Sneaking the throttle up tells you the octane, if it starts making the predetonation plinking noise (that the game seems to model) at around +7psi, it is 87. +12 psi, it is 100 octane. Greater than that, it must be 150 octane (seems a bit unlikely :)). Of course with 100 octane the boost cutout should have been virtually modified so that it is no longer a cutout, but instead controls boost at the higher +12 psi value.

The boost cutout in the Spit II is a bit strange, it just unlocks a bit more boost but clearly it has 87 octane inside as it starts to predetonate at around +7 psi.

EDIT INCORRECT STATEMENT with mixture/ rpm changes the Spit II will sit happily on +9 psi and go 320 mph IAS/TAS on the deck So it models 100 octane boost behaviour.

But if we have to have to use Spit Is and Hurris in their pre-Battle of France fuel configuration, the original (working) boost cutout would be fun! People would be using it to squeeze a little more power from their 87 octane but blowing up motors left right and centre. A bit arcade I know but I would love seeing it in MP. Perhaps a server side setting would be useful if you didn't want it ("crew chief secretly used extra thick wire on boost cutout after what happened last time" setting).

It is a problem that WEP configurations for combat edge carry little penalty if modelled correctly..because the problem is for the virtual erks or the next guy that flies your plane if problems are not addressed. Again most people would consider it arcade, but I would love to see that if you used combat concessions, you are that "next guy"...engine wear is accellerated over reality to "simulate" that effect. People would only use WEP configurations if they really thought their virtual life was in danger or interception was critical.

Well, you can dream,
camber

BTW Ramstein, great post on engine stuff

iirc camber, what you see in the spit II is acurate for what you would see when the boost cut out is used, as the actual gauge at that time only went up to 8, so that is your indication of 100 octane fuel.

Thanks Fruitbat,

I will have another look offline where you can turn off the cockpit and get a higher reaching boost guage.

I was basing that on flying in ATAG MP in the II and pulling the cutout, the engine was making the odd distressed noise I considered the devs use to signal predetonation at around +7psi, so I assumed 87 octane but I will recheck.

Would be interesting if the II modelled a modified boost cutout system but where a confused erk but in 87 octane limiting the useful boost to +7 psi :)

when using the boost cut out with the spit II adjust the fuel mix, and the engine runs fine. Have no idea if that is historical, but thats how it is in game.

Really!? I had no idea! I already felt overly advantaged in the II and that was without using the boost cutout.

Any idea of how 1) how much total boost can you get this way and 2) how much boost can you get with a healthy sounding engine? If 2) is > +7psi you are correct, 100 octane is in the tank.

Edit: In the end Spit II can happily function at +9psi and so is 100 octane

http://www.ww2aircraft.net/forum/alb...php?file=20311

http://www.wwiiaircraftperformance.o...601a-curve.jpg

http://www.wwiiaircraftperformance.o...b601-power.jpg

Note that "1 minute power" is only given "am Boden beim Abflug" (on ground for take-off) and not given for "in Bodennähe" (near ground level). There is nothing that indicates that "1 minute power" could be used up to FTH.

But I agree that the "5 minute power" at sea level is to slow for most of the presented post-patch graphs.

i remember having read on these very forums, that +12 boost was cleared only in conjunction with weak mixture. however ingame i could use boost cut-out for ages whilst having rich mixture (below 3000ft).

"Boost" is alway present, its the manifold pressure, and is increased and decreased by the movement of the throttle, from below -4lbs (closed throttle) up to + 6 1/4 lbs at full throttle. There is a limit to the time +6 1/4lbs can be used otherwise damage results. This is already coded in.

The problem may be this: if we assume that the gauge reading of +6 1/4lbs is a true value, i.e. it truly represents the maximum manifold pressure, then there is something wrong in the conversion of the boost value to thrust and speed. I don't know how this is coded in CoD but its probably somewhere in the chain of formulas and values that convert throttle position to manifold pressure, manifold pressure to engine power output, rpm setting, propeller/thrust modelling, drag factors, atmospheric pressure, and probably other factors, to arrive at speed.

I assume several of these are the same for both Spitfire and Hurricane (same engine, same propeller) so it could be a common factor (engine modelling) and/or different aerodynamics for the two aircraft (they are both undermodelled at low altitude).

Is there a graph for the spit IIa (real life, before and after patch lines)?

Thats the Spit Mk I, he asked for the Mk II mate, As far as i'm aware B6 hasn't posted the Mk II yet.

I was pointing to
I don't have any other graphs or information now.

Boy! your easily pleased!!!

No, its more of a glass half full/half empty type of thing I am sure....

yes maybe your right ??

It's hard without knowing how the devs have configured their flight model formulae, but it seems likely to be as you say. Of course coding in this way makes it hard to calibrate to exact speed vs altitude (or any other) profile, as max speed (i.e where accelleration = 0) is at the termination of a chain of calculations where changes along the chain (to constants or altering the formulae themselves) can have unpredictable effects, and it may come down to laborious trial and error getting the two curves to match. Of course just getting the speed vs altitude curve right does not mean sim fidelity, for example if the plane accellerates in a non historical way to get there.

But we can compare along the chain where there is historical data, and currently boost is kind of right but the final speeds are wrong.

There are some problems with boost though, last night looking at the offline with cockpit off (apologies, I'm sure similar data has cropped up in many other threads):

Spits and Hurris have a boost controller (red cutout "off") that gives +5 1/4 to +5 1/2 psi minus boost cutout at 3000rpm full throttle. Boost drops as soon as the throttle is retarded, so CoD model is closest to the "variable datum" type of boost controller for all RAF aircraft. This should be +6 1/4 psi though.

Oddly, CoD boost increases to about right (+6.2 psi) when rpm is decreased to the 2600-2800 rpm range. From my reading this is incorrect, the boost controller should not be rpm dependant.

The Spit II with boost cutout activated (sea level; full throttle) achieves +9psi at 2600 rpm, +8psi at 3000 rpm (again the rpm-boost quirk). So the CoD Spit II acts most like a 100 octane conversion where the cutout was modified for +9 instead of +12 psi. At 3000rpm, the engine makes some distressed noises/ vibration but does not fail. Dropping rpm to 2600 rpm and/or putting mixture to weak smooths the engine. At sea level, boost cutout on, rad half open, weak mixture, 2600 rpm and +9 psi boost I could maintain 320 mph (IAS and TAS) for a full sortie. That is some serious speed (512 kmh)

The CoD Spit Ia/Hurri act (in boost characteristics) like 100 octane conversions where someone drilled the wrong size holes in error and gave tiny increments in boost. You can see the boost cutout effect in Hurri at 2600 rpm if you turn it off and on and watch the boost gauge(+6.2 to +6.4 psi), alhough I could not detect a speed difference. So you can't tell if the virtual tanks have 87 or 100 octane in them, it doesn't matter because the boost never gets high enough.

But getting the boost behaviour exactly right doesn't help much if the model does not pass the next check..that the boost combined with other inputs ends up producing overall performance in line with historical norms...which is more of a problem.

I didn't realise the Spit II could sit on 320 mph. Had an online sortie on ATAG, I just zigzagged up and down the channel on the wavetops at 320 mph, and started bouncing people from below. Fun, but not very historical I guess :)

camber

Well ... all the problems that they have adapting the performance curve to RL comes from the inefficiency of the formulae to bring the fast boost of the pressure changes (+6 psi at full throttle).

A base curve and then add pressure changes to the FM, as I said, is a effective method to fix this, but is only my opinion.

Whatever is the solution I hope that they are on it.

Given that most fighting tends to happen below 6,000m, the current game is closer to the flight tests than the patch.

Good work camber, thank you. FM's are a complete mess today, but the team is working on that. Let's hope that the final result is better than what we have now, with uber Spit II and Hurricane, and poor G.50 crippled to complete uselessness.

Cheers!

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???

What are you guys talking and complaining about?

I can´t hear all this complaining anymore.

Emil that was actually a joke about G.50... Good one btw. :grin:

If you are trying to say that his arguments are foul because he does fly blue, then the same applies to red pilots.

Ergo, nobody flying red or blue only may argue.

I don´t think you want to say that, do you?

We all took a concious decision, to have 1C concentrate their ressources to make a better graphics model.
It is therefore beyond doubt that we will have to wait for the graphics model to get finalised and afterwards, the long, hard discussion about the flight models will start.

I have always avoided discussions because speed is only one parameter; There is a lot more which plays a role in a dogfight.

What I would really like to see is that somebody downloads the CoD plane parameters and creates an IL2Compare like we had for IL2!

http://grathos.de/temp/CoD/il2compare_bf109_spit.jpg

http://grathos.de/temp/CoD/il2compare_funplot.jpg

If we have that, we will have the required transparency to start discussions.

As I had commented in the improvements thread months ago, watching the "wing load" responsiveness of the airplanes (can be seen by the planes flying reasonably well with half-wing sawn off) makes me believe that, as far as the FM of COD is concerned, "speed" is one small piece of the puzzle.

~S~

I think his "U's" with the two little dots over them are overmodelled........

Ubermodelled...

This is another problem with the engine model - switching to auto weak mixture at high boost settings should have quite the opposite affect, causing severe detonation and rapid engine damage. The manual states a maximum boost of 3 3/4 lb when using a weak mixture. These are 100 octane settings and you can halve them if using 87 octane.

I agree Sutts, that mixture feature of the CloD Spit II does not make sense. I can live with it but I would rather it not be there.

I also am concerned about the fact that top speed in the Hurri and Spits is achieved at lower rpm than maximum (2600-2800 vs 3000). I have not seen any historical reference that to get top level speed, you should retard rpm. On the contrary, maximum speed data is given for 3000rpm.

I suspect it is a consequence of the rpm-boost quirk of the CloD engine model. Lowering rpm from 3000 to 2600 in CloD adds some boost (although in reality the boost controller should be keeping boost constant regardless of rpm). More boost = more power = more thrust in the flight model (presumably), so the non-historical boost increase at lowered rpm gives a corresponding non-historical speed increase at lowered rpm.

In the various Spit Speed tests in the Nat archives I actually came across one report that actually achieved better speed at 2800RPM than 3000RPM. It was so unusual that it was cause for comment in the report. I will try and hunt it down.

Edit Found a ref to this phenomenon in Hurricane I ROTOL trials. In the Hurricane test they specifically tested for for this phenomenon as it had occurred on Spit I ROTOL trials on aircraft N3171 in AAE/692. This reference in the Hurricane report AVIA 16/681 Hurricane I ROTOL Trials.

Here is the relevant page in the Hurricane tests that references it:

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

EDIT 2
Here is the text from the N3171 report:

4.2 Controlling R.P.M. Speed tests were made at three heights below full throttle height with the boost pressure maintained constant at 6¼ lb. per sq.inch whilst the R.P.M. was varied over a range from 2600 to 3000.

The results show that the maximum level speed is reached with the airscrew controlling at 2800 engine r.p.m. On increasing the r.p.m. to 3000 the speed was reduced, on the average by 4 m.p.h.

For the particular engine fitted there is a reduction of 17 b.h.p. at constant boost (+6¼ lb) when the r.p.m. are increased from 2800 to 3000. The loss of speed is therefore probably due to the loss of power accompanied by a slight decrease in airscrew efficiency. The matter is being further investigated by Messrs.Rolls-Royce and Messrs.Rotols. It will be noted that reducing the R.P.M. from 3000 to 2800 lowers the full throttle height by 2000 feet.

Conclusions.

1.This aeroplane has a much better take-off and climbs faster than other Spitfires fitted with wooden fixed pitch or metal two pitch airscrews.

2.There is a drop of 13 m.p.h in maximum level speed compared with the 2-pitch airscrew aeroplane but of this, 8 m.p.h. can be attributed to sources other than the airscrew.

3. Below full throttle height an increase in speed of about 4 m.p.h. can be attained by controlling the engine R.P.M. at 2800 instead of 3000.

4.The limiting diving speed can be reached much more rapidly with this aeroplane than with Spitfires fitted with fixed pitch wooden and 2-pitch metal airscrews.

This text cut and paste coming from here:

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

I'd just like to add that RPM does affect boost in reality. The greater the RPM, the greater the suction in the intake leading to lower intake pressure. With lower RPMs the suction reduces and the pressure rises slightly.

However, if the boost is high enough for the boost cutout mechanism to be in operation then no change in boost should be apparent with a change in RPM since the mechanism will automatically compensate to keep boost at it's maximum permissable value. I believe this is what you are referring to. Just don't want people thinking the whole link between RPM and boost is a quirk in CloD.

Hi Sutts,

I agree with you but would state it slightly differently:

Although manifold pressure ("boost") and rpm are linked in a physical sense, the Merlin boost controller manipulates the throttle valve to maintain a boost pressure setpoint. It will compensate for rpm and height changes within it's mechanical limits, and thus keep boost pressure constant.

IvanK:

Very interesting report. It does make sense that the airscrew efficiency curve could cause a reduction in thrust with increasing rpm. But I think you are right that this is an unusual finding in a specific case that requires investigation. There is not much point giving 3000 rpm availability on the CSP control generally (as was ubiquitous on Hurris and Spits) if this represents a thrust reduction due going past an optimum on a prop efficiency curve.

Sorry for the stupid question, but summaryze the report, what is the maximum achieved speed on Hurry Rotol and Spit Rotol?

Spitfire IA (beta patch): 248 mph @ 0m

That's a 'tad' bit too slow. I assume this is for combat rating, 6.25 / 3000..?

All out +6.25 and 3,000 RPM, however change from 2,600 RPM to 3,000 RPM didn't make a notable difference. Radiator open/close also didn't change anything

So still that radiator bug ...

My fear is that there are so many issues and considering that they are currently working on the big issues right now and how long it takes, it will take another 3 years to fix this sort of issues ... *sigh*

Should be 284mph (305 :(

My friend tells me he can't get Spit II to more than 270mph @ 500feet, should be ~290mph :(
He also finds max Hurricane speed at SL is 220mph. Not even what they published for the patch (272mph) or RL data 262mph.

EDIT: I found Hurri gives 234mph

Well, my beta patch gives me CTDs within 5 mins of taking off in ATAG MP. 50% of people chatting seem to be in the same boat, whereas the other 50% are totally CTD cured for hours on end. Go figure :)

So what else to do but go single player, turn off the cockpit and get SL speeds for the patch?

Technique: skim waves, centre ball, settle as close as possible to 0fpm. As noted above the tool tip in cockpit view does not agree with the cockpit guage (possibly it rounds down to nearest 10mph?), all these speeds are based on the guage in no cockpit view.

My SL speeds and observations:

Spit II
275-280mph 3000rpm full throttle (~6.25psi boost)
290-295mph 3000rpm full throttle red tab (~9psi boost)

rpm boost quirk (drop in rpm increases boost) is gone, boost stays constant with rpm. Dropping rpm to 2600rpm does not lead to speed increase any more

Spit Ia

255-260 mph 3000rpm full throttle (~6.25psi boost)

As per Spit II, rpm boost quirk is gone (boost constant with rpm), and dropping rpm now does not increase speed. Boost cut out still does nothing.

Rotol Hurri

240-245mph 3000rpm full throttle (~5.25psi boost)

Boost quirk is still there for the Hurri, i.e boost increases to approx correct value (+6.25 psi) only if rpm dropped to 2600rpm. However unlike before, this does not increase speed.

109E4
with prop auto at 2300rpm only
450-460kmh (280-286mph) at 1.35ata
460-470kmh (286-292mph) at 1.45ata


On the bright side, E4/Spit II matchup may be rather "balanced" with max SL speeds almost identical. Both Spit Ia and Rotol Hurri are now "I like a challenge" only planes :)

camber

I think you're right about the tooltip and I removed that from my post but we can't get those speeds on line :(

I was read the cockpit gauge. But there could be simple texture mapping errors. I think we should standardize on use of no-cockpit-view gauges for test flights.

Hmmm, is it possible that there is a difference between offline and online performance of aircraft in Cliffs of Dover? I was unable to achieve (online) the values that Camber did offline.

EDIT: Just did some testing of the Spitfire Ia and IIa offline and online (ATAG Server). Looks like there may be a different curve for the Spitfire IIa between online and offline flying. This might explain the difference between what Camber recorded and what is happening online. Please ignore the A2A data -- apples to oranges to Cliffs of Dover.

http://theairtacticalassaultgroup.co...2238#post12238

@BlackSix: Why does the Spitfire Mark IIa fly so differently offline vs online? Per my findings on #6 post at http://theairtacticalassaultgroup.co...2238#post12238

It might help if you reupload the file to this forum or somewhere the devs dont have to sign up to read (as I assume they wont bother).

I tried Jimmy -- the pdf file exceeds the minimal 19 kb limit set by 1C. I'll see if there isn't another format I can use that will be accepted by this forum.

I have to think that if a dev can't be bothered checking into the forum of one of the busiest Cliffs of Dover servers.....then they'll hardly be bothered looking at a chart....:rolleyes:

Another interesting test to perform with the Spits is maximum speed in a dive.

It's difficult to get over 400mph, even from 15,000ft in a vertical dive, and if you force it to 420mph, your ailerons and rudder fall off. This is in the Ia and IIa, the MkI seems more resilient, but still no more speed IIRC.

Although any speed trial is difficult at the moment with the over-sensitive/non-functioning throttle control.

I have noted the same during my roll rate tests with the Mk II, its very hard to reach 400 mph. This was before the beta patch.

Screen shot it and post as .jpg

That works! :grin:

Please keep in mind that A2A is not equal to real life flight tests. These comparisons say and mean nothing.

That is not to say that the CoD data is correct but who knows about the truthfulness of A2A data.

Just because A2A claims their models be absolutely accurate (that's their selling claim) does not make them absolutely accurate per se.

Interesting stuff, Snapper, thanks for posting, even if it is a depressing read....

The A2A data doesn't enter into it. Please read my post more carefully next time. I was drawing attention to CoD's offline vs online performance data. However, 1C should already be aware of this discrepancy -- it IS their sim after all.

Just a wild guess and don't laugh...is possibly a head wind:-P

Definitely a good thought, Slip. I don't believe winds are programmed in either the offline or online (ATAG server). Even so, I'm not sure wind would have too much (if any) effect on INDICATED airspeed per my chart. It certainly would on TRUE air speed.

Yea I remember having trouble turning on ground in ATAG 1

I'll check into that. Engine torque would also affect ground handling AFAIK.

BTW, I'm no test pilot -- real life or virtual. I certainly invite anyone/everyone to try this or any variation and/or aircraft. It was Camber's post somewhere in this forum that got me to wondering about offline to online. The A2A data I had done earlier for my own interest -- apples to oranges as I've already expressed on this forum.

Wind does not/cannot affect IAS or TAS (True) , it will affect Ground Speed. From IAS you determine TAS you then apply the wind effect to get Ground Speed.

I reasoned that wind would be the only variable between the on-line and off-line test's done by Snapper...pitot tubes have been installed in RL with environmental faults (inherent errors) magnified due to placement error, and after all we are dealing with a game here, and proper coding being done.:-P

Thanks for the clarification, IvanK!

Hmm, my test results are fast compared to others on this forum...as a professional scientist this worries me :) Obviously on-line "test piloting" is not particularly precise, but SL speeds should be reasonably comparable I think with care.

I can get on ATAG and fly for hours without CTD post patch as long as I stay away from other planes :( so I retested on-line and offline for the Spit II only.

To summarise:

* significant and unpredictable speed differences between the tool tip (roundimg to 10mph doesn't help), the cockpit gauge and the no-cockpit gauge.
* No real difference between online and offline speeds for me, and Spit II offline speeds consistent with last test
* full to 1/2 radiator makes a small difference (about 10mph)
* canopy closed/open makes no difference

Again, ball centred, wave skimming, time allowed to settle.

Online speeds are
(tool tip reading)/(approx cockpit gauge to 5mph)

1/2 rad +6.25psi 3000rpm 270/275
full rad +6.25psi 3000rpm 260/265
1/2 rad +9psi 2800rpm 290/290

Offline speeds we can also add the no cockpit gauge
(tool tip reading)/(approx cockpit gauge to 5mph)/(no cockpit gauge)

1/2 rad +6.25psi 3000rpm 260/270/270
1/2 rad +9psi 2800rpm 280/280/293

I think the new patch is trying to make me feel better, it CTDs so fast so it lets me get there faster than others :grin:

Thanks for posting this, Camber.

Your SL data for the IIa squares with what I got for both online and offline ie 290 mph IAS +/- 2 mph. Where my data began to diverge (offline vs online) is when I climbed to 5,000 feet and 10,000 feet. The online Spit IIa begins to seriously decline in IAS while the offline Spit IIa holds a fairly steady IAS right up to 10,000 feet (and possibly higher -- did not test beyond 10K).

I can't fathom why the two flight models for the two same aircraft should be so different at emergency combat settings ie. 2800 at full overboost. (The needle goes off scale on the boost gauge, so I can't tell if it's +9 lbs or +12 lbs -- or something else for that matter).

I haven't used the no-cockpit gauges but why they woulld read differently is a real worry, surely these are the same gauges or are the gauges in the cockpit set in the 3D model whilst the no cockpit gauges are 'made' separately. In that case either the gauge plates could be calibrated differently or perhaps the needle rotation formulae are different.

Regarding the on line versus offline difference it could be that different atmospheric conditions are modelled, e.g. perhaps one is a 'standard day' and the other not or perhaps both are not and are different from eachother. Then again, the test environment used by 1C could be different from both.

http://stoenworks.com/Tutorials/Unde...0airspeed.html
That standard is:
1. at sea level
2. standard day (temperature, humidity)
3. a barometric setting of 29.92 inches of pressure

If any of these criteria are off then the indicated airspeed will be different than the actual airspeed of the aircraft.

http://www.elsevierdirect.com/compan...-d/default.htm
IAS = 'indicated airspeed'- this is the speed displayed on the aircraft instruments. As such it is a function of height (static pressure) and forward momentum (dynamic pressure). The value displayed on the instrument will be affected by local atmospheric conditions and by errors from the installation of the sensors on the aircraft.

I've added the 1940 documented data from spitfireperformance.com charts to your jpg so we can see how all the IAS's are off if its supposed to be a standard day.

However, note that the IAS's given for Spitfire IIa in the spitfireperformance chart we have been referring to is 'raw' so I have deducted the Positional Error Compensation and the Comp. figutres to give the true IAS's. I suspect this is what os modelled in CoD, I doubt if they modelled in a Positional Error or Comp. error.

I for my part as an almost exclusive 109 Pilot must say that i am having nice challenges against spits now after the patch. Seemingly the Spit IIa isnt as uber as it was before the patch. I cannot understand why everyone always complains until their plane is absolutely uber modeled so skill doesnt count anymore. I can understand if someone moans because his side/plane got nerfed to hell and back. But that is seemingly not the case with this patch. The 109 does roll like a tank since the newest patch but it at the same time feels much more authentic this way if you take into consideration the airspeed at wich this rolls take place. It just feels right.
I cannot tell about the Spitfire or hurricane. Only that good pilots make good fights now and not just the plane.

Winger

"Only that good pilots make good fights now and not just the plane."

That is all well and good to an extent. The boys in our JG26 LW arm are now saying that things are way too easy and no longer a challenge because the109 has lost it's stall characteristics. He is now able to out-turn Spitfires easily, no longer needs to be careful about approach because if he gets involved he can escape anyway.

I did a quick test on the Hurricane Rotol and Couldn't get more than 230mph ASi out of it, trimmed, level flight, at various RPm (best 2650). According to this:

http://www.wwiiaircraftperformance.o...rricane-I.html

I should get 261mph with the Rotol which is 290mph TAS. Essentially the Hurricane is 50-60mph too slow. When I looked at the graphs B6 provided too the 109 is faster than RL up to 6km too, so we have an inaccuracy of around 80mph!!

Also, I've found problems in climb. Maybe it's me but the Spitfire Ia ROC seems to fall off badly above 16kft. I can only seem to manage about 1000fpm constantly when I should be able to manage 2400fpm @ 15kft and 1,840fpm @ 20kft.
I may have a bad airspeed or RPM for the task but I was using 2600rpm and full power rad open trying to maintain 160mph ASI. Temperatures looked dangerously high, I found 140-150 seemed to give better climb.

This is too inaccurate as a test, I would like some opinion on it though.

I fought a Spit yesterday and dove away. The guy followed me and i wasnt able to get distance on him. He seemingly then lost sight of me and broke off. Wich was my luck. I think people should Fly the crates for a while untily they know the strengths and weaknesses and then after maybe 1-2 weeks start complaining. But not already at day 1.

Winger

EDIT: But i surely understand red jockeys if the get upset fast. I would too. Did so already. Until i then realized it was me and the situation and not the plane:)

I attacked Wellingtons at 3.5 km height on ATAG on my 109-E1, and suddenly found 3 or 4 Spits and Hurries buzzing around. After a bit of DF I dove for life, but at least one if not 2 Spits managed to stay on my tail down to < 1 km.
They should have hit some controls because trying to shake them again I went into an unrecoverable spin and crashed into the channel.

That's not to deny the FM mistakes of red fighters, which MUST be corrected asap by the devs, but to hint that the Bf-109 is not that invicible machine.

Cheers!

I haven't managed to find a fight yet since the patch, I get up to 18kft where the Spitfire is meant to be stronger but nobody is ever there. It sucks.

I am going by what our JG26 boys have said, DavidRed has had a couple of 'Ace in a Sortie' flights already - that's just turkey shooting. Maybe some are turkeys but they aren't all turkeys. Like I say, I don't know personally so will have to experience it. I fly the Hurricane and it is 60mph slower than it should be (30mph @ 6.25lbs), which is massive for the slowest fighter anyway. I did a quick turn test with one of our 109 guys and he could stay with me easily in sustained 180mph turn - I should have been able to tail him in 2 circuits like that (though I appreciate that's not how to fly a 109!)

Your link don't work.

The RL tests measure the 109's 1.32 ata power. It's the "no WEP" line. :-| This graph is slower 35 km/h (on the deck) than it should.

http://www.sukhoi.ru/forum/attachmen...3&d=1334842797
- pilot's manual
- game with WEP
- game no WEP

I can't follow you calculations, how do you get 80 mph difference...?

Updated it.

OK, so you cannot apply wep? What happens then? (I understand the wep limit should be 1 minute correct?)

Speed is just one part of the puzzle anyway, ROC, turn stall etc etc....... We need some sort of IL2COD_Compare

Looking for 109 speed graph for patch i think speed is quite accurate modeled - max speed 500 km/h at the deck and 580? km/h at FTH, without 'WEP?" it looks like about 460-470 km/h which is accurate for RL serial test 109 with 1.3 Ata power ( 5-minutes WEP power).

But looking at patch speed graph for british fighters there is really big joke for me.
Hurricane MK1 with CSP at 6 1.2 lbs power should reach ab. 260 mph ( 420 kph) at the deck and some raported after patch it could reach only 230 mph (370 kph)???? WTF???
50 km/h difference? And these is without 100 octan fuel performance.


Strange that 1C FM engeneer could achived very accurate results for 109 E in game ( beta patch) but srew a lot with british fighters performacne ?!

If the Hurri slower 30 mph, and the 109 slower 10-20 mph, then the difference is 20-10 mph... not 60.

The WEP have limits, we didn't testing with the new engine, but we notice, the cooling leak causes engine failure. It should testing the other systems before I say anything.

We notice a huge difference the old and the new FM. Have to learn to fly with all planes.The stall characterics changed drastically (the 109's too). Far worse agile, and far less stability on slow speed (and i like it. I just flew gliders, but the high AoA flight, the stall, spin and the wing flaps looks more real now). The spin is stronger, and hard to recover. No more tight turn with open flap (you dorp your speed quickly, and fall like a rock - particularly the Spit/Hurri's Split-Flap).

I've only just flown the Hurricane and the SPIT IIa briefly today, well frankly on first impressions its not much fun. I wouldn't be confident taking either into a dogfight against a 109.
Flying the Spit didn't feel like a plane that struck fear into the Lufwaffe.
Is there some kind of agenda from 1C? I can't imagine what it is, but it seems that for flight sim enthusiasts they have no love for two of the most famous planes in history. Ho Hum.

Tom, this is @ 10kft and with any 12lbs boost. You are talking about SL where the 109 difference is greatest, the difference there for the 109 is about 15-20kmph? I think its a big difference. When the Spitfire II was 30mph too fast the LW complained so much it was banned, suddenly there are few on the LW fighting the cause for the RAF types which run way too slow now.

Interesting what you say about coolant now causing engine failure - that's a big fix and will be interesting to see the behaviour.

I'm not say, the small difference is OK, I also want that the graphs become accurate. I'm just say, the difference isn't 60-80mph (as the IIa was).

Yesterday one of my mate notice this coolant leak, but need further testing - or ask Luthier the detailed change list...

One of you is talking 50mph and the other 50km/h.

Lack of 50 km/h is at only 6 1/2 lbs power settings for beta patch Hurricane but when you know that BOB Hurricane MK1 was flying with 100 Octan fuel at +12 lbs emergency power the difference - lack of speed would be 50 mph at the deck.

Hi Tom, I know that 1C has stated the IIa was 60 mph faster than the RL Spitfire IIa, but my tests to 10,000 feet (where the majority of ATAG combat takes place) seems to place it within 20 mph (too fast). Have you seen the chart(s) that 1C has used? IC has adjusted the RAF fighter FM's downwards accordingly and I'm frankly puzzled by this turn of events and the reasoning or logic behind it.

Hi. No, I didn't see the 1C measurement results, but i don't understand, B6 why would say this, if it's not true.
ps. Some kind of Clod-compare would be the best. Everyone would be happy if we can get accurate and detailed performance graphs.

Actually to my understanding the flaps of the Spits and Hurris were only used for landing. Unsurprisingly because they really destroy any speed quickly. They are rather airbrakes than high lift devices considering their angle at which they are exposed to the air stream. For the seafire they used a trick to lock shortly and only once per flight the flaps to a halfway position for takeoff.

I checked 109 sea level speeds and nothing change comparing to pre beta patch version.

109 E-3 (manual prop)/ E-4 auto prop

1.35 Ata at 2400 RPM - 450 kph at 0
1.45 Ata at 2500 RPM - 460 kph at 0

So i think there is no changes in FM of 109 ( also there is no info about it in beta patch notes). So still 109 is to slow ab. 20 km/h at 1.3 Ata power and ab. 20 km/h at 1.4 Ata - so generally 40 km/h slowier at the deck.

Moreover i checked british fighters in beta patch and i got:

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 at deck at 6 1/2 lbs
285 mph at deck at 9 lbs ------ should be 286-290 mph so it is very accurate result!!!!

Still no 100 octan fuel performance - so no emergency +12 lbs.

P.S.

Test was made in the same map and settings over channel at near sea level, i checked different RPM settings, radiator etc. for all fighters and choose the best ones to achive the best results.

strange....I just couldn't get the mk2 spit above 240 mph at sea level

Do you use some kind of level-flight aid or just a very steady hand? I would like to test at FTH as well but I have trouble keeping it within +/- 50m.

Trimm trimm trim and steady hand plus watch vario + above 10 years flying sims + 8 years real life flying + ab. 3 years flight model modding and testing in il2 :)

Are you sure it is MKII not MK1?? Cause i cant get MK1 above 240 mph at sea level - max speed 238 mph at 6 1/2 lbs.

SRY i made mistake in these post cause i miss Hurricane with SPitfire. Of course SPit MK1a in beta patch reach 255 mph at 6 1/2 lbs and Spitfire MKII reach 268 mph at the same boost.

I will check again, sounds like thats what happened.

Of course, this is only used for landing in RL.
But in the game, some (less experienced) red pilot use the landing flap to tight turn :rolleyes:. Of course small angular velocity can be obtained for a short time, but the speed dropped fast - even before the patch too. Now the consequences is much more drastic.

Kwiatek, did you make those tests off line or on line? Just curious because on line at 100 feet off Manston we couldn't get more than 248mph in Spit MkIa. Not that 8mph matters when its so far off.

Is there any way to check the atmosphere settings for on and off line? Is one or neither a 'standard day'?

Hi Klem,

Here's what I got yesterday for the Spit Ia at sea level:

6.5 lbs, 2800 rpms: 245 online, 249 offline
6.5 lbs, 3000 rpms: 252 online, 253 offline

Did you try offline at 3000 RPM? Comparing different RPM settings is rather counter-intuitive.

I don't understand your question. Both online and offline are there, for two rpms. What's so "counterintuitive" about that?

Ups sry i made mistake Hurricane ( 238 mph) speed with Spitfire MK1 (255 mph).

I got 255 mph for Spitfire MK1a at sea level. Speed achived with acceleration in level flight not a dive.

All test i made was offline, single player mission, quick fly over channel.

WOW. I can't read. Sorry.

I don't even-

255mph amost identical to ATAG_Sappers figure of 253mph for Spit Ia offline.

I think there's an atmosphere issue between on line and off line.

btw guys when you read off those ASI mph figures on the spitfire performance charts don't forget to deduct the PEC and Comp errors, e.g. SpitIa at 10,000 feet, ASI 286mph, Corrected (CAS) 275.4mph.

Hi all,

My speeds are somewhat higher than others
For example, I get around 255-260mph SL offline for Spit Ia (3000rpm, +61/2psi)

EDIT: what am I talking about? Looking back the speeds are pretty similar for the last few posts. But will leave following points in:

A few things:

The cockpit gauge is not very precise, and tool tip gives speed in 10mph increments only (the no cockpit guage is a lot better). How are people recording +/-1 mph speeds online, is it estimating from needle position? I feel like estimating within 5mph is pushing it, and above 280mph the marks are in 20mph increments so to 10mph is pushing it.

The radiator position does give small increments in speed. I found that open to 1/2 open radiator gives 5-10mph extra (1/2 open to closed gives -250mph :)). What radiator position are people using?

I also found that accelleration can be glacially slow for the final few mph. How long are people attempting to wave skim at their best 0fpm before recording a value?

Cheers, camber

I have my trim controls assigned to two levers on my CH Quadrant which gives me pretty precise control in levelling out at the proscribed setting. That said, it sometimes took a minute or three before I was satisfied that I was flying perfectly level at the exact altitude. By that time the speed is rock stable. I'm now virtually hands off so I can easily zoom in to the airspeed gauge to get a reasonably accurate reading despite the coarse scale. I agree the speeds will be +/- a few mph, but it's not too hard to make a fair estimation -- certainly within the precision of any concern.

All my readings were taken with radiator at 50%.

I'm running about 50 feet off the waves. I use my trim axis, not my joystick axis, to make the final delicate adjustments to maintaining perfectly level flight. I found it exacting and time consuming, but the airspeed held rock steady so I felt confident in the reading I was taking -- within +/- 2 mph at the most.

Hopefully others will have data, including the LW a/c, in case others fall on the short side of the curve at various altitudes.

Other parameters, in time, will need to be looked at as well such as turn radii, dive speeds, climb rates, etc.

Have you found a magical way to trim in the roll axis?
Or do you: 1. trim the rudder to offset the roll (thereby introducing drag) or 2. just hold the stick over (well, that would introduce some drag from the ailerons too I suppose).

Hey guys,

Just out of curiocity (and 'cause I am too thick to go through the 30 pages and understand):

Does the current Spit MK1a and Hurri MK1a performance (after the alpha patch) match the graphs that were posted on page 1 of this thread????


~S~

Please, can someone summarize the results of the tests? I'm lost between RL, offline, online speeds of Hurricane, Spit I, Ia, IIa etc.