Mike Williams
Senior Airman
- 572
- Oct 19, 2006
Thank you for the informative post Juha!
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Thank you for the informative post Juha!front line units usually used 91-95 oct Soviet fuels or 100 oct LL fuel (outside mid-1942 - early 43, when Soviet fuel supply was in crisis), I have seen Soviet speed graphs for P-39Q showing the speeds with 95 and 100 oct fuel. Soviet 95 oct was usually used by M-82F and FN engines, so La-5F, -FN, La-7 and Tu-2. Spitfires and P-39s used usually 100 oct LL fuel. IIRC one big offensive was delayed a couple of days so that they could store enough LL fuel for a P-39 fighter division for the operation.
IIRC The La-5FN tested at Rechlin was old and worn-out a/c. On La-5FN max speed, the new production a/c usually were capable to 625 to 635 km/h and the 648 km/h was the speed of a prototype. Soviet prototypes in early 40s tended to be faster than the production a/c.
P-39 and P-40 are aluminum airplanes. At least the ones operated by the Planes of Fame are. There is some steel, but the structure is aluminum. Landing gear oleos are steel along with a few other items. The engine crankshaft, camshaft, and other parts are steel, but the engine case is aluminum. Mixed material is normal due to strength and heat requirements.
If you tried out aluminum valves in the engine, they wouldn't last longer than a couple of minutes, if that long. In an Allison V-1710, the valve are Stellite (cobalt-chromium alloy) with powdered sodium fill for heat dissipation.
As askedView attachment 600662
Ps. and my previous message was mostly based on messages made by the pseudo name Altea here in 2009.
Hey Mike Williams,
In the early-2000s (around 2008?) I ran across a serious paper written on the history of the Russian/Soviet Union/Russian/Ukranian/etc oil industry from the 1800s on to the early 2000's. The author is an accredited historian and his name is Alexander Matveichuk. The paper covers most of the things related to the Russian/Soviet oil industry - ie history and exploitation of oil fields, quality of the crude oil, transport, refining/production, and changing technology. It had a fairly extensive section on the subject of aviation fuel quality and availability in the WWII period. I have not been able to find the original paper/history in a complete form on the internet, however there appear to be pieces of it available on various websites. Some of the websites require memberships.
An abbreviated account of the section on WWII aviation fuel quality, production, and acquisition can be found here:
"Oil of Russia : www.oilru.com : No. 2, 2011 / A HIGH-OCTANE WEAPON FOR VICTORY"
If anyone finds the complete paper on the internet I would very much appreciate it if you would let me know.
I'm sure it was liquid back in WWII. Not so sure about today, but cannot speak for the state of it before it is exposed to air when a valve gets destroyed. Generally, I leave broken valves alone, and not just because they are not repairable.
That's what they taught us in mech school.Metallic sodium is solid at room temperatures. Melting point is about 208°F.
That's what they taught us in mech school.
Hey BiffF,Peter,
Thank you! The numbers look fairly close (I don't have them memorized). Did the Germans use Allied fuel to get these results? Did Allied fighters and bombers use the same grade fuel? I would guess it was all the same...
Cheers,
Biff
Hello Juha3,
My original statement regarding maximum speeds for the La 5FN was that anything from about 390 MPH to 403 MPH seems pretty reasonable and that they seemed to vary.
What do you believe the altitude was that the aircraft achieved its maximum speed?
- Ivan.
Thanks Juha, I'll study on that chart a bit and try to figure out how the P-39 compares with US tests. The first question that comes to mind is - was the engine operated at lesser RPM, boost or both with the differing fuels. Looks like they were using Military power and I wonder what manifold pressure was used. Also wondering if it had external wing guns.
Hmmm, From: Pilot's Flight Operating Instructions for Army Model P-39Q-1 Airplane
War emergency 3000 RPM, 57" MP, critical alt with ram 9,000'
Military power: 3000 RPM, 44.5" MP, critical alt with ram, 15,500'
Max continuous: 2600 RPM, 39.2" MP, critical alt with ram. 14,000'
From MEMORANDUM REPORT ON Pursuit Single Engine P-39Q-5, AAF No. 42-19615
329 mph at SL with 57" Hg.
374 mph at 10,000' with 57" Hg.
It varied between 5700 m (N 39211525 625 km/h) and 6200 m (N 39210466, 633 km/h) and one figure 634 km/h at 6250 m without info on the serial number and Gordon & Khazanov gives 620 km/h at 6150 m. I don't know are the figures compression corrected.