P-40B Climb rate to low...

[Morpheus]

Awsome!!!!!!!! Site Neil. Ty for posting this link.

[Widewing]

Originally posted by Neil Stirling1
Not the P-40 B but still an excellent site.

Thanks Peril.

http://www.raafwarbirds.org.au/targetvraaf/p40_archive/p40_data.htm

Neil.

Actually there is a considerable amount of P-40B/C data on this site. It will be useful in getting the P-40B flight model corrected.

For example, the AH2 P-40B can only manage 332 mph at 15,000 feet (tested). However, the Tomahawk I could reach 365 mph at the same altitude. Since we have the P-40B/Tomahawk IIA, with the additional weight of externally sealed tanks and two additional MGs, plus more armor, it should weight about 370 lb more than the Tomahawk I. No way that difference would reduce speed by 33 mph.

I have seen figures of 355 mph (Wright Field) and 352 mph (Eglin) for the P-40B.

There are also MAP discrepancies between test data and the AH2 FM. Climb rate is off by nearly 600 fpm at sea level.

I will compose a post to the Aircraft and Vehicle forum and send an e-mail with the appropriate test data to HTC.

There may be a argument that the P-40B is hardly worth fixing, because it is rarely flown. However, if the FM was corrected it certainly would get a great deal more use.

We can thank EdXCal for reviving this issue. It should be corrected, just like the Bf 109G-14 should be corrected.

By the way Edward, the material on this website is what historians call "primary source documentation". This is the stuff HTC needs to change flight performance. Books on the topic will not suffice, unless they contain references to original documents or provide copies of that data. Nonetheless, thanks for bringing up the topic again. It needs to be looked into.

My regards,

Widewing

[Widewing]

Ok, e-mail was sent to HTC with whatever hard data I had. There should be enough to justify reviewing several issues such as these:

AH2 P-40B performance, as measured with E6B, 50% fuel.

Speed at 12,000 feet: 321 mph (between 19 and 21 mph too slow)
Speed at 15,000 feet: 332 mph (between 20 and 23 mph too slow)
Max MAP: 38 in/hg (should be 40.5 in/hg at sea level)
Max climb rate at sea level: 2,100 fpm (should be 2,680 fpm, minimum at 100% fuel)
Time to 15,000 feet: 7.3 minutes (should be 6.1 minutes)

Just remember that HTC is up to their ears in getting TOD online, so this will be back-burner stuff. Don't expect it to be addressed in the near term.

My regards,

Widewing

[Squire]

The Q. I would have comparing the P-40B and the P-40C would be "wep" output for the engines, as it appears the AH2 P-40B does not have a wep rating.

Also, Neils docs shows the P-40Bs Allison engine as 1040hp max, with no overboost available, either.

That has to be the reason the AH P-40B performs as it does. 1040 hp engine with no wep in a 7300 lb airframe is not going to climb very fast, compare it to a Bf 109E-4 that is 1500 lbs lighter, and has an unboosted climb rate of @ 2700 fpm, with a higher hp engine (1100hp).

The FMs have to follow the laws of physics.  Why would a P-40B that is 1500 lbs heavier climb as well as a Bf 109E? When the engine is no better?
 
The A6M2 climbs at  @ 2700 fpm as well, with a 950 hp engine  (unboosted) and a weight almost 2,000 lbs lighter.

So far nobody has made any comparisons and asked that question.

[EdXCal]

Well thanks for the informations, I know the information I gave isn't official, but it's the best I could do at the time, I have many books I could use to post and all say ALMOST the same thing, speed seems to change a little from book to book but are in the same 10 mph ballpark. The Climb rate stay's pretty much the same and thats what I was gunnin' for. The reason I posted that book is because it had the most information and seemed to match up with the rest of my books then the rest.

I really do hope that AH touchs up the flight model, with a little better climb and speed, more people would be willing to fly and as you said, may become more popular.

Edward

[Widewing]

Originally posted by Squire
The Q. I would have comparing the P-40B and the P-40C would be "wep" output for the engines, as it appears the AH2 P-40B does not have a wep rating.

First, the P-40C was an improved B model. It added a bit more armor, internally sealed fuel tanks and the plumbing and shackles for an external fuel tank. Both were powered by the V-1710-33 engine, neither having a WEP setting. However, the P-40C's increased weight cut into climb and the increased drag, combined to small extent with the extra weight, reduced speed.

I had always felt that the AH2 P-40B model was lacking in both speed and climb.

Think about this... A Merlin powered P-40F made 1,100 hp at MIL power @ sea level. A P-40B had 1,040 hp available at sea level. Now, the P-40F was 1,300 lb heavier than the P-40B, so one would generally conclude that the B model should climb as fast or faster than the F model, IF the F model used just MIL power. But, our P-40B climbs far slower than an F model at MIL power. There's no doubt in my mind that the AH2 P-40B climbs considerably slower than it should when below Critical Altitude.

Add to that, it's also at least 20 mph slower at Critcal Altitude than it should be. If that doesn't point to a problem with the flight model, I don't know what does.

Also, I tested rate of roll and found that at 280 mph the AH2 P-40B rolls left at 101 dps and 98 dps to the right. We saw a document that shows the P-40 rolling at 110 dps at 30 lb stick force. Even that seems slow when we look at the roll chart in Dean's America's Hundred Thousand, where we see a roll rate of 135 degrees per second at 360 mph. No stick force is provided. If you read this report you will see that the P-40's ailerons were extremely effective and considered substantially better than the Spitfire's or Hurricanes.

So, there's several issues that should be reviewed by HTC as time allows.

My regards,

Widewing

[Squire]

According to the AH chart, the P-40B outclimbs the P-40E (we dont have an F), when both just use MIL power, not by a lot, but it does.

...and you still have not addressed the rate of climb of the 109E, Spit IA, and A6M2 using MIL power, all of which are MUCH lighter a/c with similar hp outputs.

A6M2 does @2700 fpm initial, just how close to climb rate do you think a P-40B is going to be, when it does 2200 fpm already, weighing 2000 lbs more??? We supposed to beleive it could climb as well? because it had a sharkmouth?

At some point gravity has to be addressed.

Personally I think a lot of the Curtiss data looks very optimistic, to say the least. I think HTC based the FM on more reliable, and beleivable data than some sources claim. They have not said what they used, but then they usually don't.

I like the P-40, I think it had a very good record in combat in the Pacific and CBI, and it has some great qualities, and I think it tends to be under rated in some histories...but it never climbed as well as its contemporaries, allied or axis.

As for its top speed at FTH, that may be off, I would like to see some more on USAAF tests on it. I can certianly beleive that it could have done @ 350 mph as an inline design with a 1000 hp engine.

They can review it as they see fit, I would be curious to hear their take on it.

[EdXCal]

Were giving you realistic stats and your trying to compair the P-40B to other planes in the game?! Can you find any reports against that climb rate? I havn't found anything stating the climb being that low.

Now, as for the 109, the 109E-4 only had 174.05 sq feet of wing area at a weight of 5,875Ibs with 1175hp and climbed at 3,510fpm with full power and WEP.

The P-40B (From what I can find, not the game stats) with 236 sq feet of wing area at ( at 50% fuel, only stats I've got) 6,835Ibs with 1040hp climbed 15k in 5.1 minutes (roughly 3,000 fpm).

So, the P-40B does have a larger wing area at 1,000-1,300Ibs heavier, with about 100hp less, I think that 3000fpm climb isn't that unrealistic, though 2,690fpm does seem a little more realistic.

Edward

[Squire]

It woudnt be the first time that HTCs data did not reflect #s from a book, that doesnt mean that they are wrong. If only a/c research was that easy.

As for the 109E, it climbs @ 2700 fpm in MIL power, with WEP it does 3500 fpm initially.

Spitfire IA does @ 2600 fpm initially in MIL power, and @ 2900 fpm in WEP. < 1000 lbs lighter than a P-40B.

A6M2 Zero is 2000 lbs lighter, and climbs at 2700 fpm in MIL power.

All three are 1000-2000 lbs lighter with similar (or better) engines.  

And your 3000 fpm quote you keep using is from the P-40 prototype, and are Curtiss #s.

The P-40B does not have an overboosted engine (WEP) and so its climb rate should be about where it is. *IF* it had WEP which-it-does-not, I could see 2600 fpm on it, in MIL power only, at 7300 lbs, 2200 fpm (at sea level) is as much as I can beleive it would climb.  

To sum up, HTC is right, and your not.

[EdXCal]

First off, I can't even find stats for the prototype XP-40, atleast not in climb rate. It was actully faster, and had a more powerful engine. But in order to make it "cheaper" the super turbo charger was removed, making it a far less powerful engine. The prototype engine was an Allison V-1710-19, 1160hp at SL and 1000hp at 10k.

And so far all you can state is comparisons with game aircraft stats and saying that I'm wrong, not a single shred of proof, not from the net, from books, offical USAAF documents. Nothing... Widewing and I have mounted much information and a few other people have posted P-40 webpages with much information to support what we've said, so why are you still fighting this...? And just because you feel like "HTC is right and I'm wrong" doesn't make it true.

Edward

[StarOfAfrica2]

I have XP-40 stats at home, will post them for you later.  I cant guarantee they are right though, just published.  

The thing with getting info out of books is, most publishers dont seem to verify the author's data.  It's expected that he did that himself.  And more and more often we are finding out that they didnt, or simply relied on data published by someone else.  So you get a whole string of books that can be published with erroneous data.  The more that get published, the harder it is to get folks to believe its not factual.  Thats why (as Widewing pointed out), HTC wont use information from books or the internet to make changes to their FM's, unless they reference original test data as their source (and hopefully provide photocopies of the original documents as well).  Even some very well respected authors have published books with incomplete or jsut plain wrong data because it was accepted as fact when the book was written.  There are even a few out there who have been known to "stretch the truth" a little, when it suited them or their story.

[EdXCal]

That is true, but I would find it odd that so many of my books have the same stats, but we area talking about a plane thats been around almost 70 years. I wish I could find a P-40 pilot, actully I do know of one whom is still alive, I spoke of him in an ealier post, his name is Col. (Now Gen. from what I know) Robert Scott, he flew side by side with the flying Tigers and them became the commanding officer of the 23rd fighter group in China. He still lives in Georga with his wife and heads a flying group called the Twin Tigers, I met one of the guy who's part of that group on AH2, there a flight training school and an acrobatic team. Maybe if we could somehow get ahold of him, he may either be able to support our climb rate idea's or be able to find us USAAF reports on the subject.

Edward

[rshubert]

Originally posted by Squire

The P-40B does not have an overboosted engine (WEP) and so its climb rate should be about where it is. *IF* it had WEP which-it-does-not, I could see 2600 fpm on it, in MIL power only, at 7300 lbs, 2200 fpm (at sea level) is as much as I can beleive it would climb.  

To sum up, HTC is right, and your not.

You're negotiating, not referencing or calculating.  Sources?

[Krusty]

Uh... negotiating? wth? Doesn't look like that to ME.

[rshubert]

Originally posted by Krusty
Uh... negotiating? wth? Doesn't look like that to ME.

When start seeing words like "I believe" and "I can't accept" and the like in reference to this kind of discussion, it's certainly not arguing the facts.  What would you call it?