The P40 thread

[Guest deleted@83466]

The P-40 could be switched to Fixed Pitch propeller mode, and the switch operated the pitch of the blades and then fixes it there, where it will obviously rise or fall with different power and airspeed.  In automatic mode, it operates as a constant speed prop with RPM controlled by the lever on the throttle quadrant.

[Multimetal]

The P-40 could be switched to Fixed Pitch propeller mode, and the switch operated the pitch of the blades and then fixes it there, where it will obviously rise or fall with different power and airspeed.  In automatic mode, it operates as a constant speed prop with RPM controlled by the lever on the throttle quadrant.

Gotcha-is this modelled in the game, and I'm just not properly set up?  Right now for me the prop pitch control uses the panel switch, not the quadrant lever.

[LukeFF]

Gotcha-is this modelled in the game, and I'm just not properly set up?  Right now for me the prop pitch control uses the panel switch, not the quadrant lever.

 

You should be using the same controls that are used to control prop RPM in the Yaks, La-5, LaGG-3, etc. Again, don't bother with the switch on the panel. There is always the manual, too, that explains this. (hint: page 30).

 

Some period documentation about this:

 

Edited September 5, 2017 by LukeFF

[Venturi]

Numbers from that data sheet are CALCULATED (i.e. theoretical), actual weight of P-40E was simply higher.

 

Standard weight of P-40E-1 in game - 3819.1 kg ( 8420 lbs.). Standard weight is in this case airplane with full fuel + 1410 rounds of ammunition.

 

Standard weight of P-40E according VVS manual - 3819.6 kg ( 8421 lbs.). In manual is 3840 kg, but with 1560 rounds of ammunition (weight 212 kg).

 

Standard weight of P-40E (No. 40-384) according USAAF report - 8434 lbs.. Weight without ammunition in that report is 8011 lbs., 1410 rounds of ammunition weights 423 lbs.. - http://www.wwiiaircraftperformance.org/P-40/P-40E_40-384_PHQ-M-19-1300-A.pdf

 

Standard weight of P-40E (No. 40-633) according USAAF report - 8458 lbs.. Weight without ammunition in that report is 8035 lbs., 1410 rounds of ammunition weights 423 lbs.. - http://www.wwiiaircraftperformance.org/P-40/P-40E_40-633_FS-M-19-1580-A.pdf

 

Standard weight of P-40E-1 according Boscombe Down report - 8408 lbs.. This is measured weight, not theoretical. And there is no extra equipment, it is standard P-40E-1.

 

Conclusion - weight of P-40E-1 in game is on point.

 

----------

 

 

Sorry I couldn't get back to you earlier or more completely earlier. 9 hour licensing exams come first - I have been studying for three weeks hard, and IL-2 is a hobby only. As much as I enjoy our little debates on the forums and trying to make it better and more historical for everyone myself included. In fact, I just spent another $500 on a new PC video card just for IL-2BOx. I have purchased every product from this team to support their efforts, because no one else has done as good a job so far in recreating, in a holistic sense, WW2 aerial combat.

 

So, with that out of the way, now that I have the day off, let's have a discussion. Thanks for bringing up all your sources.

 

First off, I don't think we actually know what "standard weight" is in the game, because the devs don't specify. We don't know if this is 100% fuel, or if it is 80% fuel, or what. Unless you have insider information that I don't. 

 

We have to work off of the dev's EMPTY weight, and add in the fuel and ammo and pilot and oil. Because that's where most of the discrepancies are... and all the other loadout stuff are details that add to this basic error, and obscure it.

 

Since you value lines up exactly with the US Army weight data sheet, I assume you are getting your weight for ammo there, which is correct in my opinion - as this was the actual form which allowed for actual pilots to calculate actual flight ranges and loads. But, you cannot discredit a source and then later use it credibly!

 

So, to start with the actual numbers, let's look at the EMPTY weight for the IL-2BOx P-40E. It is: 6775lbs (3073kg).

 

Again, we assume this is the aircraft weight with everything, except consumables and removable/optional items, but we don't know for sure. This is a different definition from the US ARMY empty weight on the weight data sheet, and from the "tare" weights on the Boscombe Down trials (below).

 

First, let's do some number crunching to see if the total weight listed in the game is actually accurate, using the devs listed "empty weight" for the plane, and adding in the additional missing weight from the ammo, pilot, fuel, and oil, using the US ARMY weight data sheet.

 

+423lbs for 1410rds ammo 

 

NOTE: By the way, 1410 rds is the correct standard load of ammunition, not 1686 rds. This was an ARBITRARY amount of ammunition that the Boscombe Down test aircraft had in it and is the ONLY place I can find this amount of ammunition for the P-40E listed anywhere. In fact, why it is aberrant is explained, below. The MAXIMUM DESIGN ammunition load is 1870 rds, which is 561lbs, per the US ARMY weight data.

 

Continuing on...

 

+873lbs for 145gal fuel

+180lbs for pilot

+120lbs for 16gal oil

 

That is a total addition of 1596 lbs we must add to the "IL-2BOx empty weight" number. Then, add in an additional 83lbs for the extra 276 rounds of ammunition (weight per round extrapolated from the previous number) that we have in the game's "standard load" of 1686 rds.

 

= 8454 lbs, NOT 8420 lbs!  So, if the IL-2BOx EMPTY weight of 6775 lbs is correct, then the total weight with the "IL-2 standard load" is actually too low!

 

Anyways, continuing on...

 

The source we should be using for EVERYTHING - and which you maligned but actually still used to get data on the ammunition - is the ACTUAL data source used for calculating flight loads and ranges! Red outlined paragraph. Right in the 1943 US ARMY Pilot's Instuction Manual for P-40 D&E (April 10 1943). 

 

 

You can see here, this page details the weight data referenced in the 1943 manual, above. It is a page from the same manual, 1941 version, for the P-40E (revised Feb 1942). You will note that the aircraft EMPTY weight, with radio, is 5894 lbs (2674kg). That is in comparison to the IL-2 Developer's empty weight of 6775lbs (3073kg)!

 

 

 

 

 

The major thing I actually dispute is the IL-2 BOx empty weight of 6775 lbs and the "standard configuration" loadout. If you look at the US ARMY P-40E weight data, above, it gives the aircraft weight as 5982 lbs (with radio), +384lbs (6x 0.5cal BMG), +108.5lbs (armor), +94lbs (gun equipment)... for a total weight of 6569 lbs, which is the equivalent weight in the "IL-2 BOx EMPTY WEIGHT" configuration. 

 

In other words, when we look at a apples to apples comparison, there's a 207 lb discrepancy, where IL-2 BOx overweights the basic weight of the plane against the US ARMY weight data sheet for the aircraft. This US ARMY data should be the ACTUAL design data for the aircraft! Not some beat up test examples which had miscellaneous equipment in it from all sorts of testing and various configurations!

 

So let's look at your sources and see how credible they are, in terms of EMPTY WEIGHTS:

 

1. VVS Manual: I don't have this source. I would appreciate your giving it to me for review. However, I do not see why this should be given MORE credence, as you seem to do, than the 1943 US ARMY aircraft manufacturer's manual or data sheet.

 

2. P-40E 40-384: 8011 lbs. You say this is simply minus ammo from the IL-2 "Standard Load". Therefore, empty weight on this plane would be 8011 lbs, minus fuel (which we will assume is 550 L / 145 gal), minus oil (16 gal), minus pilot. That would leave an empty weight of 6838 lbs as the equivalent "IL-2 BOx empty weight". This is 63lbs over the IL-2BOx listed empty weight of 6775 lbs, and 270 lbs over what the US ARMY weight data says. 

 

3. P-40E 40-384: 8035lbs. This aircraft is similar to the above configuration, without ammo but with full fuel, and with additional mounting for a spin chute. Therefore, similar calcuations apply, and show 87lbs over the IL-2BOx listed empty weight of 6775 lbs, and 294 lbs over what the US ARMY weight data says. 

 

4. Boscombe Down P-40E AK.572: 8480lbs, AL.229: 8485lbs

There were at least two P-40s in these trials.

 

(in Parts 8, 11, 15 here: https://drive.google.com/drive/folders/0B4pKiKbNRE3FdWNMVEhyZU1kV0U?usp=sharing )

 

This aircraft (AK.572) was "an early 4-gun model and has neither the various American modifications and improvements, nor any British modifications incorporated, and IS NOT THEREFORE REPRESENTATIVE OF KITTYHAWKS THAT WILL BE IN USE OPERATIONALLY." My question is, what are these various American and British modifications and improvements?

 

Also, then why is the presumably much lighter aircraft AK.572 approximately the same weight as AL.229? The answer is, because AL.229 had only 4 guns in it, but 6x blast tubes. THAT is why the below weights page has an odd amount of ammunition listed in it. And why we have an odd amount of ammunition in IL-2BOx for the P-40E.

 

 

 

And what we see here, is that the service weights include everything from item 15 and up. That includes:

 

-two radios (really, did all these aircraft come with two wireless sets?)

 

a. R3003 wireless and controls of 34lbs

b. TR90 wireless and controls of 53lbs (this was, by the way, an OPTIONAL addition, conforming to the US ARMY SCR-274-N, British pilot manuals do not mention it as being standard, except as noting provision for its installation)

 

 

The US ARMY radio sets for the P-40E were completely different, and were the SCR-274-N (for command unit purposes) and SCR-522A (voice transmission). The SCR-274-N was OPTIONAL. Another reason why not to mix data sources, and to use the US ARMY "EMPTY WEIGHT with radio"!

 

-200lbs for pilot and chute 

-4x 0.5cal BMG guns with 6x blast tubes and housings, for 463lbs 

-gunsight camera of 10lbs (which we don't have in our plane)

-additional "extra" oil of 1.5 gal over required for 13.5lbs

 

For a total tare weight of 1358lbs, which brings the aircraft weight to a convenient 8500 lbs! Of course, they are ALSO using 123gal fuel, not the 145gal which is in game and in the US ARMY manual weight data page!

 

If I take the "tare weight" of this aircraft and bring it to the "IL-2 BOx standard configuration" weight, using the US ARMY weight data, it goes like this:

 

Tare 6098 lbs 

+384 lbs for 6x 0.5BMG

+94 lbs for gun equipment

+157 lbs R3003 wireless and controls

+1697 lbs for pilot, 1686 rds ammo, 145gal fuel, and 16gal oil

 

=8430 lbs! With 145gal fuel and 6x 0.5BMG. This is not equivalent to the British test plane weight as it has 123 gal and 4x guns - if you are going to use that line of reasoning.

 

I think THIS is what the developers did: They took this British test plane's "tare" weight, and used the American US ARMY weight data to add the items for flying condition weight.

 

What they SHOULD have done, is take the design "empty" weight of the plane from the US ARMY weight data, as well as the weight data for the loadout from there, thereby keeping all their tabulations from one source. Additionally, this is the DESIGN data, and is not compromised by being taken from a beat up aircraft of unknown condition, with unknown additions and options, and with unknown weight measurement errors!

 

The bottom line, for the "IL-2BOx standard load", is that if we are using the US ARMY weight data source, then the airplane should be 8,012 lbs with 1410 rds, 6 guns, and 145gal fuel.

 

If we are using the Boscombe Down British source, then the airplane should be 8,500 lbs with 1686 rds, 4 guns, and 123gal fuel.

 

If we are using the US Army "test planes" 40-633 and 40-384, then it should be 8434 lbs and 8458 lbs, respectively, with 1410 rds, 6 guns, and - I assume - 145gal fuel.

 

NOT 8420 lbs for 6x guns, 145gal of fuel, and 1686 rds of ammo, which is what it is currently.

 

See what I mean?

 

In fact, the maximum permissible weight for all forms of flying was 8500 lbs, and anything over was only straight flight or slight gentle turns!

 

 

 

 

 

 

 

OK on to the other issue:

 

Why do you think that 90 mph stall speed is conservative?

 

Because the PEC correction gives it a -2 to -3mph to indicated at those speeds, and PEC is not modeled in the game. Therefore stall speed should be 88-90mph, not 95mph. This has a huge impact on CLmax. BTW, engine off / engine on, is a red herring. The plane stalls at 95mph with engine on in the game. You can see my analysis of the Boscombe Down and US ARMY PEC data (which you are aware of, already): https://forum.il2sturmovik.com/topic/25323-p-40-turn-rateflight-model-check/?p=428013

 

 

Additionally, beyond my previous analysis,

 

 

This also lines up with multiple pilot accounts and other manual versions, See the following, plus others. Just search on the forum for "P40 stall speed" with quotes around it like I posted here, you will find many posts. (Not you, Farky, you already know.)

 

[blitze]

I went out and purchased the P40.

 

First flight on WOL, she takes a bit of punnishment. Got chewed up in a bounce and she nursed me back to my home field. Darn German pilots on comms ))

[Venturi]

The P-40 D and E had the option for a mechanical or electrical bomb release system. That is most likely why you don't see those switches modeled and why, in the game, the bombs are armed via the handle on the floor of the cockpit.

 

 

I see the dash controls were actually separate from the bomb controls under the fuselage. The dash controls were used to control the 6x wing-mounted 120-lb bombs which the P-40E was capable of carrying.

 

So you're right, there are floor controls for bombs. And I'm right, there are also dash controls for bombs. Both.

 

The P-40 widely carried these bombs, and they should be an option for use. They're great for killing soft vehicles and such.

 

 

Edited September 5, 2017 by Venturi

[Multimetal]

You should be using the same controls that are used to control prop RPM in the Yaks, La-5, LaGG-3, etc. Again, don't bother with the switch on the panel. There is always the manual, too, that explains this. (hint: page 30).

 

Some period documentation about this:

 

01.jpg02.jpg

Thanks!  Great source too.

[LukeFF]

 

 

I see the dash controls were actually separate from the bomb controls under the fuselage. The dash controls were used to control the 6x wing-mounted 120-lb bombs which the P-40E was capable of carrying.  

 

So you're right, there are floor controls for bombs. And I'm right, there are also dash controls for bombs. Both.  

 

The P-40 widely carried these bombs, and they should be an option for use. They're great for killing soft vehicles and such.

 

 

Good catch! The only reason I can think as to why they aren't in the game is because the Soviets never installed the bomb racks to drop them (which would be FAB-50 in this case).

[unreasonable]

I cannot quote Venturi's post 645 - but looking at the last two documents on PEC I wonder how much credence to place on a table that shows a PEC for 60 mph, when the table below shows a minimum (gear up flaps down) stall speed of 80mph IAS.  This is obviously not a measured value - in addition, the lowest measured value on the chart used as an illustration is at 150mph! AFAIK not a single one of the P-40 PEC charts quoted here or in previous threads has measured values anywhere near stall speed. 

 

If you calculate for minimum operational weight minus 207lbs  (the potential overweight) and a stall speed of 88 mph you get a CLmax of 1.50, compared to 1.32 on unadjusted Tech Spec figures.  This would make it the highest CLmax of any fighter in the game by a considerable margin.  If the 88mph is for "standard weight - 207lbs" you get 1.76 - more than the airfoil IIRC.

 

The game Spitfire, with almost the same wing section, has a game CLmax of 1.34 at min stall speed and min operational weight. It has a min game stall speed some 12 mph higher than the IAS number given in the manual.  We know the reason for this: the developers are using the RAE tests, or something like them, to calculate a CLmax.  These also give a clue as to the PEC conundrum.

 

RAE tests of the Bf109 and Spitfire showed a massive measured discrepancy between IAS as observed by the pilot and as recorded by a trailing pitot at speeds close to the stall. Again we know the reasons for this: pitot tubes pointed into the airflow at an angle under-measure pressure and hence speed. Here is the table showing the measured result for the RAE tested 109. No doubt it will be argued that the P-40 installation was different: but I have yet to see an explanation of why the fundamentals should be reversed. 

 

 

It seems far more plausible to me that the correct extrapolation of the curve shown in Venturi's graph below 150 mph would be back to much higher +ve values. After all - continue the extrapolation of the same curve as in Venturi's chart and you would apparently be flying backwards when your IAS drops to zero. So the extrapolation must be wrong over a certain range. By contrast, a +ve PEC at very low IAS simply means that the indicator will show zero before you have actually stopped.

 

The Spitfire manual shows a +4 mph PEC for speeds of 100-140 mph. It does not show anything for speeds lower than 100 - and why should it?  PEC figures in manuals are used for navigational purposes, not for determining TAS at stall, a number of no interest to pilots.

 

If there are any other sources that actually measure IAS errors at stall speeds in WW2 planes, I do not recall seeing them posted.

Edited September 6, 2017 by unreasonable

[Venturi]

That is because it is a mathematical constant and you only need a few data points to determine the line equation.

 

from:

 

https://www.spaceagecontrol.com/USNTPS-FTM-C2.pdf

[Max_Damage]

I went out and purchased the P40.

 

First flight on WOL, she takes a bit of punnishment. Got chewed up in a bounce and she nursed me back to my home field. Darn German pilots on comms ))

Join red TS. But yes the language barrier However some of us can speak eng no problem and will help you.

 

Anyway i can only admire the p40. two days and two 3 kill sorties. While keeping my teammates safe. The guns are wh40k level. Also, open the canopy to look back.

http://il2stat.aviaskins.com:8008/en/sortie/log/2261357/?tour=26

http://il2stat.aviaskins.com:8008/en/sortie/log/2265101/?tour=26

Edited September 6, 2017 by Max_Damage

[unreasonable]

edit @Venturi - The most relevant section from that report states that

 

"Failure of the total pressure sensor to register the local pressure may result from the shape of the pitot static head, inclination to the flow due to angle of attack, α, or sideslip angle, β, or a combination of both. Pitot static tubes are designed in varied shapes. Some are suitable only for relatively low speeds while others are designed to operate in supersonic flight. If a proper design is selected and the pitot tube is not damaged, there should be no error in total pressure due to the shape of the probe. Errors in total pressure caused by the angle of incidence of a probe to the relative wind are negligible for most flight conditions. Commonly used probes produce no significant errors at angles of attack or sideslip up to approximately 20˚. With proper placement, design, and good leak checks of the pitot probe, zero total pressure error is assumed."page 2.26

 

This is of course a modern report discussing modern instruments. The RAE tests demonstrate that the pitots in the 109 and Spitfires tested were producing a very large pressure error at angles of attack near the minimum speed stall - ie below but approaching 20 degrees, (according to the game data). You will also remember the videos posted by glider pilots showing you the variation in the IAS as they yaw.

 

I am not sure how you derive your formula but it seems to me that the extrapolations we see ignore alpha and beta, which is perfectly reasonable for most of the operating range, but not appropriate for close to the Vmin stall for instruments of this era. If alpha is taken into account in your formula can you tell me how?  

Edited September 6, 2017 by unreasonable

[unreasonable]

I have another question for Venturi: if as he said earlier that the most important thing is that the P-40 fits into the right place in the range of aircraft in the game, what does he think the stall speed of the Spitfire Vb should be?

 

Currently it is 137-144 kph = 85 - 89 mph.  The pilot's notes say 73 mph IAS F+G up at 6,400lbs which is close to the upper end of the weight scale in BoS.  So the PEC is up to +16 mph, which is in line with the RAE findings.

 

How is a plane with a smaller wing - based on a very similar airfoil - and weighing in at least 20% more supposed to have the same Vmin as the Spitfire?  If the P-40 stall speed is currently badly wrong then so is every other aircraft for which I have been able to find a IAS Vmin.

[Venturi]

Then you should start your own topic about the Spitfire.

[Venturi]

The fact that the line formula can be generated by data points above stall speed, which predicts PEC at stall speed and thus avoids any of the associated incident angle airflow errors, is why no measurements for PEC are taken at speeds approaching aircraft stall.

 

That does not mean that PEC cannot be extrapolated all the way down to stall speed and even lower (as the manual shows), because the mathematical constants are known from data points at higher speed, and a line can be drawn for all speeds including stall, accurately.

 

We are not stalling real aircraft and in the game PEC is not taken into account. However, IT IS on real aircraft manuals.

 

When an aircraft manual says "this plane stalls at 90mph indicated" what it is saying, is that the TAS stall speed = the INDICATED AIRSPEED of stall (90mph in this example), plus or minus the PEC, to arrive at a stall TAS. That is why PEC is plainly stated. The fact that real aircraft have airspeed indicators which may not provide accurate information at the very edge of a stall IS IRRELEVANT to the game, because PEC is not modeled.

 

It is ONLY important, that we understand what TAS the real aircraft did stall at. And this was at a TAS of 88-90mph.

Edited September 6, 2017 by Venturi

[Farky]

First off, I don't think we actually know what "standard weight" is in the game, because the devs don't specify. We don't know if this is 100% fuel, or if it is 80% fuel, or what. Unless you have insider information that I don't.

 

 

We do know what is STANDARD WEIGHT in game. From game specifications - Minimum weight (no ammo, 10% fuel): 3264.2 kg . We know, that 100% of fuel is 404 kg. So to get weight of airplane without ammo or fuel : 3264,2 - 40,4 = 3223,8 kg. Now we know that let's call it BASIC WEIGHT of P-40E-1 in game (aircraft ready to fly minus fuel and ammo) is 3223,8 kg (7 107 pounds). 100% of fuel is 404 kg, 1410 rouns of ammo is 423 lbs. (192 kg). So, 3223,8 + 404 + 192 = 3819,8 kg. Conclusion - STANDARD WEIGHT 3820 kg (8422 lbs.) in game is 100% fuel and 1410 rounds of ammunition. Check my previous post to compare this weight with real data - https://forum.il2sturmovik.com/topic/14610-p40-thread/?p=506559

 

EMPTY WEIGHT - there were different standards for EMPTY WEIGHT, so I don't know how to compare them. And it doesn't matter, if we know that weight of airplane without fuel and ammo is correct, than who cares about EMPTY WEIGHT. We also know that weight of the fuel and ammunition is right in the game. 

 

 

Since you value lines up exactly with the US Army weight data sheet, I assume you are getting your weight for ammo there, which is correct in my opinion - as this was the actual form which allowed for actual pilots to calculate actual flight ranges and loads. But, you cannot discredit a source and then later use it credibly!

 

 

Weight for ammo is from various sources, not just from that calculated USAAF data sheet. Do a cross-check is always good idea. VVS manual is saying that 1560 rounds is 212 kg, therefore 1410 round is 192 kg ( 191,6 kg to be exact). Boscombe Down report 5th part - 2460 rounds is 738 pounds, therefore 1410 rounds is 423 lbs.. Boscombe Down report 15th part - 1686 round is 505 lbs., therefore 1410 round is 422,3 lbs.. RAAF report F.8 is same as Boscombe Down report 15th part.

 

 

NOTE: By the way, 1410 rds is the correct standard load of ammunition, not 1686 rds.

 

 

Sure, that's why we have 1410 rounds as standard load in game.

 

 

The source we should be using for EVERYTHING - and which you maligned but actually still used to get data on the ammunition - is the ACTUAL data source used for calculating flight loads and ranges! Red outlined paragraph. Right in the 1943 US ARMY Pilot's Instuction Manual for P-40 D&E (April 10 1943).

...

You can see here, this page details the weight data referenced in the 1943 manual, above. It is a page from the same manual, 1941 version, for the P-40E (revised Feb 1942). You will note that the aircraft EMPTY weight, with radio, is 5894 lbs (2674kg).

 

 

This isn't same manual. First version is from 1941 and revision is from September 1941, not February 1942. Data there are CALCULATED and it can be leftover from first issue of this manual in April 1941. There wasn't any P-40D or E in April 1941 whatsoever. Btw. we can not say if this data sheet was revised in September 1941, because this copy was send to RAAF and it isn't complete (there isn't amendment sheet) . If you wanna talk about weight sheet from 1943 manual, use 1943 weight sheet from there. There isn't weight sheet in this version, I know.

 

 

This aircraft (AK.572) was "an early 4-gun model and has neither the various American modifications and improvements, nor any British modifications incorporated, and IS NOT THEREFORE REPRESENTATIVE OF KITTYHAWKS THAT WILL BE IN USE OPERATIONALLY." My question is, what are these various American and British modifications and improvements?

 

 

AK 572 was P-40D, so yes, this wasn't "REPRESENTATIVE OF KITTYHAWKS THAT WILL BE IN USE OPERATIONALLY". I was however talking about weight sheet of AL 229, which was P-40E-1 model.

 

 

Also, then why is the presumably much lighter aircraft AK.572 approximately the same weight as AL.229? The answer is, because AL.229 had only 4 guns in it, but 6x blast tubes.

 

 

No. 15th part of Boscombe Down report is absolutely clear - "the aeroplane was equiped with 6 x 0.5" guns in the wing ...". And answer why AK 572 (lighter P-40D) have approximately the same weight as AL 229 is easy - weight sheet for AK 572 is with 2460 rounds of ammo (weight 738 lbs.) and for AL 299  AL 229 is with 1686 rounds (505 lbs.). So, with same amount of ammunition, AK 572 will be 233 pounds lighter.

 

 

Of course, they are ALSO using 123gal fuel, not the 145gal which is in game and in the US ARMY manual weight data page!

 

 

Units! In Boscombe Down reports, they are indeed using 123 gallons of fuel - IMPERIAL GALLONS (UK GALLONS) not US GALLONS !  123 Imp. gal = 147.7 US gal.. They are also using more oil, 17,5 Imp. gal. = 21 US gal..

 

 

I think THIS is what the developers did: They took this British test plane's "tare" weight, and used the American US ARMY weight data to add the items for flying condition weight.

 

 

And I think they did use weight sheet from VVS manual, probably cross-checked it with Boscombe Down report (and other sources) and than implement it in game. So called EMPTY WEIGHT in game is in perfect agreement with the VVS manual data. EMPTY WEIGHT (3073 kg) of P-40E-1 in game is simply airplane minus pilot, fuel, ammunition and oil.

 

 

NOT 8420 lbs for 6x guns, 145gal of fuel, and 1686 rds of ammo, which is what it is currently.

 

 

Are you aware that weight of 8420 lbs (8422 lbs to be exact, 3840 kg) in game is for 6 x guns, 561 liters of fuel ( 148 US gal, 123 Imp. gal) and 1410 rounds of ammunition ? Pretty close to USAAF P-40Es 40-633 and 40-384, isn't it ?

And is it also pretty close to P-40E-1 AL 229 from Boscombe Down report - weight of this airplane with 6 Brownings, 123 Imp. gal (148 US gal) and 1686 rounds was 8500 lbs. If we subtract the weight of 276 rounds (83 lbs) to get 1410 rounds, weight of AL 229 will be 8417 lbs.

 

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

 

 

Because the PEC correction gives it a -2 to -3mph to indicated at those speeds, and PEC is not modeled in the game.

 

 

I wasn't asking you about game or PEC. My question was, why do you thing  think that stall speed in manual is conservative. Because you were talking about amount of fuel in manual for warm-up etc. as conservative and wrote that stall speed is the same. It looks like misunderstanding, nevermind.

 

----

 

Edit: AL 299 to AL 229 and thing to think.

Edited September 6, 2017 by Farky

[unreasonable]

The fact that the line formula can be generated by data points above stall speed, which predicts PEC at stall speed and thus avoids any of the associated incident angle airflow errors, is why no measurements for PEC are taken at speeds approaching aircraft stall.

 

That does not mean that PEC cannot be extrapolated all the way down to stall speed and even lower (as the manual shows), because the mathematical constants are known from data points at higher speed, and a line can be drawn for all speeds including stall, accurately.

 

We are not stalling real aircraft and in the game PEC is not taken into account. However, IT IS on real aircraft manuals.

 

When an aircraft manual says "this plane stalls at 90mph indicated" what it is saying, is that the TAS stall speed = the INDICATED AIRSPEED of stall (90mph in this example), plus or minus the PEC, to arrive at a stall TAS. That is why PEC is plainly stated. The fact that real aircraft have airspeed indicators which may not provide accurate information at the very edge of a stall IS IRRELEVANT to the game, because PEC is not modeled.

 

It is ONLY important, that we understand what TAS the real aircraft did stall at. And this was at a TAS of 88-90mph.

 

If what you say (in my bold) is true please show where in the formula alpha is taken into account.  Looking at the report, I suspect that the cause of your problem is that you are looking at a formula that does not take into account total pressure error at all. 

 

"With proper placement, design, and good leak checks of the pitot probe, zero total pressure error is assumed."

 

The only place alpha is mentioned in the formulas is in relation to the static pressure, which is anyway mainly affected by mach and reynolds number. Again, where in your formula is Alpha?

 

 

 

Then you should start your own topic about the Spitfire.

 

Not at all, this is a completely general issue that requires a general understanding - if the P-40 pitot-static system did not suffer from under measuring total pressure at high alpha an explanation is required about how it did that.

Edited September 7, 2017 by unreasonable

[Dennis_Nedry]

I’ve been flying the P-40 a bunch recently and was wondering if the devs have mentioned anything about revisiting the engine limits recently? Great airplane but surely the Allison could hold up for more than one minute under full power.

[DBFlyguy]

19 minutes ago, Dennis_Nedry said:

I’ve been flying the P-40 a bunch recently and was wondering if the devs have mentioned anything about revisiting the engine limits recently? Great airplane but surely the Allison could hold up for more than one minute under full power.

Will skip the necro jokes ??? and just say unfortunately nope.  Maybe if we get another variant of the P-40 someday that'll be motivation enough to finally givet that ol Allison engine some adjustments to be more aligned with reality, one can hope.

Edited January 7, 2022 by DBFlyguy

[Dennis_Nedry]

Saw that after I hit submit ?

 

That’s to bad though.  Even an engine limits mod would be nice.

[Bert_Foster]

Necro additional info FWIW P40E Kittyhawk II PEC data from AVIA 18/734 in the UK National Archives:

 

 

Edited January 7, 2022 by Bert_Foster

[Denum]

I'll just say I would love better engine settings because flying it as it against E7s and F2s is horrible. 

 

 

Edited January 7, 2022 by Denum

[savagebeest]

I'd like to see a "b" version. 

[[F.Circus]FrangibleCover]

On 1/7/2022 at 8:58 PM, Bert_Foster said:

Necro additional info FWIW P40E Kittyhawk II PEC data from AVIA 18/734 in the UK National Archives:

Kittyhawk II is the P-40F/L with the Packard Merlin, not the P-40E (Kittyhawk IA). Not sure if it makes any difference to the speed corrections but worth noting.

 

On 1/7/2022 at 9:37 PM, Denum said:

I'll just say I would love better engine settings because flying it as it against E7s and F2s is horrible.

Be glad you don't have to cope with the historical B model against F-2s, or the E model we have against F-4s and G-2s over Stalingrad!

 

As usual, I'll support the addition of a tickbox modification for Unofficial Engine Settings to be added for the P-40E (and to a lesser extent, P-39L). That way, if you feel that giving one aircraft its performance based on historical record while all of the others are limited to pilot's manual settings is unfair, you can turn it off for your campaign or your server. This is basically the same thing as the 81" Mustang settings we just got with the P-51B, which are well attested to but I'm sure never got signed off on by North American.

[ShamrockOneFive]

1 hour ago, [F.Circus]FrangibleCover said:

As usual, I'll support the addition of a tickbox modification for Unofficial Engine Settings to be added for the P-40E (and to a lesser extent, P-39L). That way, if you feel that giving one aircraft its performance based on historical record while all of the others are limited to pilot's manual settings is unfair, you can turn it off for your campaign or your server. This is basically the same thing as the 81" Mustang settings we just got with the P-51B, which are well attested to but I'm sure never got signed off on by North American.

 

That's been the thing I've been calling for for years as well. It's the best compromise for the current situation that I can imagine. I suspect too that it would be something that could be done but the folks at 1CGS have a full schedule.

Perhaps sometime after Normandy officially launches we could see this be looked at.

[Bert_Foster]

7 hours ago, [F.Circus]FrangibleCover said:

Kittyhawk II is the P-40F/L with the Packard Merlin, not the P-40E (Kittyhawk IA). Not sure if it makes any difference to the speed corrections but worth noting.

Yep fair point my gaff .... here is some Kittyhawk I PEC data from the same series of Flight test reports.

 

Edited January 9, 2022 by Bert_Foster

[BMA_FlyingShark]

15 hours ago, savagebeest said:

I'd like to see a "b" version. 

I've been hoping since day one of this series to get a "b" or a "c" (or both) version of the P-40.

 

Have a nice day.

 

[BlitzPig_EL]

Me too FlyingShark.

[Trooper117]

10 hours ago, BlitzPig_EL said:

Me too FlyingShark.

 Count me in for those early P-40's...

[Danziger]

Yeap. P-40B/C does it for me. I would love an N as well. The E is just my least favorite P-40. 

[BlitzPig_EL]

Aesthetically, the Hawk 81 is the best looking of the P40s, IMHO.  It also has the highest roll rates.

 

 

 

Yours truly, standing with P40B at Thunder Over Michigan Air Show several years back.

[Jaegermeister]

If we ever get any North African or Italian add-ons, maybe we will see the F,L,M or N versions which should all be more competitive than the E version. The E made sense at the time it was released, but it's not up to par with the later aircraft on most of the maps.

 

I can see it as a collector plane with various options for 6 and 4 gun configurations, Merlin or Allison, and different boost options. 

[354thFG_Drewm3i-VR]

10 hours ago, Jaegermeister said:

If we ever get any North African or Italian add-ons, maybe we will see the F,L,M or N versions which should all be more competitive than the E version. The E made sense at the time it was released, but it's not up to par with the later aircraft on most of the maps.

 

I can see it as a collector plane with various options for 6 and 4 gun configurations, Merlin or Allison, and different boost options. 

Unfortunately the e isn't up to the standard of later released planes in the sim because it was one of the first collector planes and has only seen one minor revision to some of its lift and drag values. I've noticed later US planes having much more liberal engine limits in sim, including the new p-51B. It is long since time for the e to be fixed.

[Trooper117]

Is Russia... Russian P-40 fly's you.   

[Traffic]

On 1/10/2022 at 12:41 PM, Jaegermeister said:

If we ever get any North African or Italian add-ons, maybe we will see the F,L,M or N versions which should all be more competitive than the E version. The E made sense at the time it was released, but it's not up to par with the later aircraft on most of the maps.

 

I can see it as a collector plane with various options for 6 and 4 gun configurations, Merlin or Allison, and different boost options. 

 I agree. The P40E was a 1941 model. And by 1942, they, along with every other 1941 model aircraft, was obsolete by 1942. The P40 was constantly updated and upgraded and the unsung hero, along with the Wildcat, who both did all the heavy lifting before more advanced aircraft began hitting theaters. A P40L/M/N would be awesome. The fact that the Merlin was available, doesn't mean it was better. The later Allison variants were quite the contenders. 15 minutes of combat power vs 5 for the Merlin. Horsepower was very similar. 

 

Personally, I love the P40, and is my favorite plane to fly. You just have to keep your energy up and it'll do everything you ask it to do, except endless speed bleeding tight turns with 109s. I just avoid turn fights and keep the speed above 275 and it's perfectly fine. I much prefer ground weed whacking in P40s vs anything else. ~300 - 310mph on the deck at max cruise is pretty good for a 1941 variant. So, in my opinion, the P40 is a contender, when flown to its strengths. They were front line fighters until 1943 when they were replaced by P47s and P38s, but they flew until the end of the war. 

 

Against 109Es and early Gs, it can hold its own. But I'd also like to see the time limits changed a bit, as well as a later model, like an F/N/M. I think the N model was the most widely produced. We have what 8 109 variants and 7 190s. Whats 1 more P40?

Edited March 18, 2022 by T241Traffic241