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EJGr.Ost_chamel
12-26-2004, 09:16 AM
Hi folks,

reading in the database of PF I was astonished to see, that the P-39D2 is stated there with an engine performance of 1590 hp. I was astonished about the huge difference to the 1150 hp of the P-39D1 and so I did a bit fo googling - but all I could find were several references mentioning the D2 with a performance of 1320 hp.
So, does anyone have a good source backing up the 1590 hp for the P-39D2?

Thanks in advance

EJGr.Ost_Chamel

EJGr.Ost_chamel
12-26-2004, 09:16 AM
Hi folks,

reading in the database of PF I was astonished to see, that the P-39D2 is stated there with an engine performance of 1590 hp. I was astonished about the huge difference to the 1150 hp of the P-39D1 and so I did a bit fo googling - but all I could find were several references mentioning the D2 with a performance of 1320 hp.
So, does anyone have a good source backing up the 1590 hp for the P-39D2?

Thanks in advance

EJGr.Ost_Chamel

Willey
12-26-2004, 11:21 AM
Bump http://forums.ubi.com/images/smilies/16x16_smiley-surprised.gif

airdale1960
12-26-2004, 01:04 PM
My books say from a 1150 hp to 1325 hp.

EJGr.Ost_chamel
12-27-2004, 04:26 AM
*Bump*
Noone with any sources?

Greetings
Chamel

Kwiatos
12-27-2004, 04:43 AM
I mailed about these plane with Oleg M. i recive some data ( not real document) about 1590 HP emergency power for D-2 . But i still doubt that P-39 D-2 from 1941 was so good like in PF ( expecially in climb rate)and have better performance than P-39 Q-10 from 1944.
So i banned P-39 D-2 like Mig AM-38 in my servers with the same reason - unbelivable perfomance expecially climb rate.

EJGr.Ost_chamel
12-27-2004, 05:12 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Kwiatos:
I mailed about these plane with Oleg M. i recive some data ( not real document) about 1590 HP emergency power for D-2 . But i still doubt that P-39 D-2 from 1941 was so good like in PF ( expecially in climb rate)and have better performance than P-39 Q-10 from 1944.
So i banned P-39 D-2 like Mig AM-38 in my servers with the same reason - unbelivable perfomance expecially climb rate. <HR></BLOCKQUOTE>

Question to all: Is This topic worth a debate in Oleg's Ready Room?

Chamel

Stiglr
12-27-2004, 11:26 AM
Sure it is.

The "answer" of course is that the P-39 has almost always been smiled on and given a lot of extra oomph in climb, turn and handling that keep it from displaying traits that give it the "average at best, P.O.S. at worst" reputation it so rightfully deserves.

faustnik
12-27-2004, 11:48 AM
America's Hundred Thousand states the horsepower for the P-39D-2 at 1590 (War Emergency). It also states that it was not produced until June 1942.

DangerForward
12-27-2004, 12:07 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by faustnik:
_America's Hundred Thousand_ states the horsepower for the P-39D-2 at 1590 (War Emergency). It also states that it was not produced until June 1942. <HR></BLOCKQUOTE>

Hi Faust, I was confused by the table in AHT showing the P39 engine power. It looked to me like the P39 wasn't cleared for War Emergency Power until the "L" model, and therefore the max power was Takeoff @ 1325hp. On page 190 the author mentions Combat or War Emergency not being added until later models of the P39.

faustnik
12-27-2004, 12:58 PM
Interesting, thanks DF! http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

FA_Maddog
12-27-2004, 03:58 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Stiglr:
Sure it is.

The "answer" of course is that the P-39 has almost always been smiled on and given a lot of extra oomph in climb, turn and handling that keep it from displaying traits that give it the "average at best, P.O.S. at worst" reputation it so rightfully deserves. <HR></BLOCKQUOTE>


The Russians used it with great success on the Eastern Front. Some of the top aces of USSR flew the P-39, so what does that make the German planes deserve?

DangerForward
12-27-2004, 04:18 PM
As a side note on the engine power issue, the gauge in the D2 cockpit shows 42"Hg at 110% power, which would equal "Military Power" @ 1150 hp.

From looking at Il2compare 2.5 the 100% power curve seems similar to what is in AHT, it's the 110% curve where speed really jumps. I'm not sure what the P39D2's main opponent was, but in il2compare it blows away the early zeros until the Hamp(a6m3). I remember the advice on the P39 in the Pacific being to stay below 15000 feet and above 300mph, this doesn't seem to bear out. I think the 110% power setting could be the problem.

SkyChimp
12-27-2004, 05:22 PM
All P-39Ds were powered by the V-1710-35 engine. Rated powers were as follows:

Military Power
==============
1,150 hp
at 12,000 feet
at 42" hg

Take-Off power
==============
1,150 hp
at Sea Level
at 42" hg

War Emergency Power
===================
1,490 hp
at 4,300 feet
at 56" hg

All ratings given at 3,000 rpm on 100/130 grade fuel.
The V-1710-35 was one of the first Allison engines to get WER ratings because, in part, it had been considerably strengthened (strengthened crankcase) over the version that powered the P-39C.

I'm not sure what the P-39D-2 is climbing at in this game, but it wasn't a bad climber in real life. Top speed at 12,000 feet was 368 mph. It's sea-level climb rated was 3,750 fpm. Time to climb to 15,000 feet was 5.7 minutes. Turn radius was 780 feet at just above stall speed.

Source: Vees for Victory and Cobra!

WUAF_Badsight
12-27-2004, 05:42 PM
SkyChimp , your saying that any D series P-39 should have 1490 Hp in FB if manifold pressure reaches 56" max ?

because if the D2 has 1590 Hp now , & thats accurate , then its no wonder it performs as good as it does

look at how fast other fighters are in FB that have around 1600 Hp

SkyChimp
12-27-2004, 05:49 PM
I didn't check America's Hundred Thousand for info, since there are better (dedicated) sources out there on the P-39D and its engine. I'll look again to see (I think I may even have a chart or two), but I didn't see any ratings of 1,590hp. That's 10hp more than the P-39N and P-39Q.

faustnik
12-27-2004, 05:55 PM
Page 191 SkyChimp.

SkyChimp
12-27-2004, 06:03 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SkyChimp:
I didn't check America's Hundred Thousand for info, since there are better (dedicated) sources out there on the P-39D and its engine. I'll look again to see (I think I may even have a chart or two), but I didn't see any ratings of 1,590hp. That's 10hp more than the P-39N and P-39Q. <HR></BLOCKQUOTE>

Oops, I made a mistake.

WEP rating for P-39D was 1,490hp
WEP for P-39K/L/M was 1,580hp.
WEP for P-39N/Q was 1,410hp.

SkyChimp
12-27-2004, 06:05 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by faustnik:
Page 191 SkyChimp. <HR></BLOCKQUOTE>

AHT doesn't list the P-39D with 1,590hp, so the source can't be AHT.

SkyChimp
12-27-2004, 06:08 PM
I found an Allison power chart for the V-1710-35 engine that shows this particular Allison may have actually developed more power than the official ratings, as much as 1,750hp at sea-level.

SkyChimp
12-27-2004, 06:21 PM
http://members.cox.net/us.fighters/1710-35.jpg

Published ratings seem to fall below actual power developed.

ZG77_Nagual
12-27-2004, 06:23 PM
The more I read about the 39 the more I think it's rep was formed very early on and is largely attributable to antiquated tactics and an enemy with superior training, tactical advantage and 39s that were put together hastily and hadn't had the bugs worked out. Like with alot of things - the rep stuck after the problems were largely solved. the rep stuck because the plane was largely replaced. The russians had much more of a 'make it work' mentality - so they stuck with it and got the changes.

SkyChimp
12-27-2004, 06:35 PM
I think you are exactly right, Nagual. American pilots were overwhelmed early on by battle hardened Japanese in good airplanes. Americans hadn't worked out their tactics and fought hap-hazardly. In 1942, the P-39 began to be replaced by the P-38 (which didn't fare well in its first combat, either). By the time the Americans had some reasonable grasp on tactics, there were scarcely any P-39s left. Had the P-39 been left in front-line service, like the P-40, there is no reason to believe it wouldn't have done as well.

The P-39 was as fast as the P-40, dove ALMOST as well, climbed better. And from the accounts I've seen turned as well. And the P-40 was a very successful fighter.

DangerForward
12-27-2004, 06:42 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by ZG77_Nagual:
The more I read about the 39 the more I think it's rep was formed very early on and is largely attributable to antiquated tactics and an enemy with superior training, tactical advantage and 39s that were put together hastily and hadn't had the bugs worked out. Like with alot of things - the rep stuck after the problems were largely solved. the rep stuck because the plane was largely replaced. The russians had much more of a 'make it work' mentality - so they stuck with it and got the changes. <HR></BLOCKQUOTE>

I think the main thing with the Russians is that they used the P39 in its sweet spot, below 12000 feet, while the US initially tried to use it to climb up to attack bombers. Once the US started to use the P39 for low level attacks or low cover, things went much better.

faustnik
12-27-2004, 07:21 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SkyChimp:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by faustnik:
Page 191 SkyChimp. <HR></BLOCKQUOTE>

AHT doesn't list the P-39D with 1,590hp, so the source can't be AHT. <HR></BLOCKQUOTE>

The D-2 is listed with the K. Read it again.

SkyChimp
12-27-2004, 08:03 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by faustnik:
The D-2 is listed with the K. Read it again.
<HR></BLOCKQUOTE>

OK, I see it now.

Hmmm, time to do some more reading.

Let's see, 1590 hp IS correct for the V-1710-63 engine. AHT shows the P-39D-2 equipped with that engine.

"Vee's for Victory" states that all Ds were delivered with the V-1710-35 engine. But now that I look further, it says on page 253 that all Ds (except the D-2) were delivered with the -35, but that the D-2 had the V-1710-63 engine.

"Cobra!" states on page 164 that the D-2 variant had the V-1710-63 engine.

So, all 3 books agree, the D-2 had the V-1710-63 engine, the V-1710-63 engine had WEP rating of 1590hp.

http://members.cox.net/us.fighters/types1.jpg
http://members.cox.net/us.fighters/types2.jpg

clint-ruin
12-27-2004, 08:11 PM
Sorry for the extra long paste.

A. S. What about the engine in the P-39. Was it weak? They say that it was unreliable, it was never good for the recommended 120 hours, and it €œthrew€ connecting rods.

N. G. We had Allison engines. They were powerful, but . . . the engines in the Cobras were unreliable, especially early on. These were on the English variants, the Q-1 and Q-2. Their engines were weaker. After the first three or four air combats, all ten Cobras were laid up for engine repairs.

These first Allisons did not deliver even one-half of the recommended engine hours. 50 hours was its limit, and frequently less. Normally 10€"15 sorties if they were in combat. They seized, the bearings melted; this happened to me once. I sat out for a while with no engine. They monitored these engines closely. As soon as any metal showed up in the oil, they changed out the engine. The supply of replacement engines was plentiful, but it was not always possible to get delivery of them. Sometimes they brought them in on an Li-2 [Soviet-built C-47], four in a load, such was the demand for new power plants. But just the same, despite our best efforts, there were seizures. True, this engine did not €œthrow€ connecting rods, at least this never happened to us. On type-5 and later models the engines were more powerful and reliable.

Now regarding power settings. In principle the RPMs were regulated by a conventional throttle. In the Cobras there were two regimes of throttle operation, €œnormal€ and €œwar emergency€, which was characterized by increased manifold pressure. The throttle quadrant was mounted in the [left side of the] cockpit and the pilot controlled it. The €œwar emergency€ regime had a lever position that we called €œ51 inches and 57 inches of boost€. If we were flying on Soviet B-95 fuel, then €œwar emergency power€ was set at 51 inches. If we were using American B-100 fuel, then €œwar emergency power€ was set at 57inches. Although it was mounted in the cockpit, on the throttle quadrant, the pilot did not adjust this setting. The position of the €œwar emergency power€ selector was controlled by a piece of wire that could be broken easily with greater forward pressure on the throttle quadrant.

One time I sensed a lack of power (I needed to get ahead of a German) and I thought, €œThe hell with it€! I broke the wire and selected €œ57€. Then I experienced what €œ57€ meant! My airplane leapt forward! The Germans spotted me from above and dove immediately, which was what we wanted.

American gasoline was better than ours. Not more powerful, but better. The anti-detonation qualities of our gasoline came from the addition of tetraethyl lead. After every two or three flights the engine mechanic had to clean the lead from our spark plugs. If he waited too long, a lead droplet would form between the electrodes. But this was not a special problem. Normally our spark plugs were quickly cleaned after every sortie. But with the American gasoline, this did not happen. Either they used higher octane to begin with and added less lead or they raised the octane rating with benzol [another additive]. Perhaps it was just the benzol. Because our gasoline was pink in color and the American gasoline was dark blue.

Incidentally, the Allison €œmade metal€ on any gasoline. Realistically the Allison engine began to live up to its full 100 hours of use only in 1944. These engines came in the Q-25-30. But by this time the intensity of air combat had already fallen somewhat, and the primary distinction of these types was the perceptible decrease in power output. Therefore we removed the wing machine guns. They were heavy [one Browning .50 caliber under each wing], slowed the airplane down, and their recoil was felt in combat.

A. S. Wasn€t this somewhat of a surprise, a deficiency in power output when one would think power should be increasing as the war progressed?

N. G. The crux of the matter was that from modification to modification the Cobra was somehow improved in construction, but this came at the price of constant increases in weight, which was not compensated for even by the growing power output of the engine. The P-63 KingCobra was a €œleap€. I had a chance to fly it after the war (thank God!). The strongest [P-39] in power output were the types from Q-2 to the early Q-10s, and then the power output began to fall. Again, beginning with the -10, the propellers came with a unified system of throttle/pitch, and this also did not increase survivability in combat. I€ve already addressed that.

A. S. Nikolay Gerasimovich, did you have the impression that they initially delivered the Cobra with an overstressed engine, that is under normal circumstances that Allison engine would have developed 100€"150 less horsepower?

N. G. That€s entirely possible. But in the course of the war, the Allison lived up to its specifications. You have to give the Americans their due.

edit: I should mention that NG is almost certainly talking about the D1 and D2 rather than Q1/Q2.


http://lend-lease.airforce.ru/english/articles/golodnikov/part3.htm

clint-ruin
12-27-2004, 08:17 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Stiglr:
Sure it is.

The "answer" of course is that the P-39 has almost always been smiled on and given a lot of extra oomph in climb, turn and handling that keep it from displaying traits that give it the "average at best, P.O.S. at worst" reputation it so rightfully deserves. <HR></BLOCKQUOTE>

Hi Stiglr,

I was wondering just where you're pulling this from specifically. I could make a guess, just by the smell, but I'd like you to name the orifice.

DangerForward
12-27-2004, 08:55 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SkyChimp:
http://members.cox.net/us.fighters/1710-35.jpg

Published ratings seem to fall below actual power developed. <HR></BLOCKQUOTE>

It also might be that it could develop more power, but only for a very short periods of time. Say less than the 5 minutes. I bet a lot of warbird engines could crank out more than their wep rating for some short period too.