In 1942: top 3 Allied fighters

[fastmongrel]

E-GEH-16

Look under the last heading titled "Performance of the Mustang I and IA", paragraph No.36.:
"...The British have operated at full throttle at sea level (72"Hg) for as much as 20 min. at a time without hurting the engines. According to them, the Allison is averaging 1500 hours between bearing failures as compared to 500 to 600 hours for the Merlin."

1500 hours !!!! thats an awful lot of sorties even for wartime especially as the RAF used them for Tactical Recce and wouldnt have flown 6hour escort missions into Germany. I know the RAF kept the Allison engined Mustangs for as long as possible but 1500 hours for a fighter engine is an awful long time.

 

[tomo pauk]

Kool Kitty89,
Thank you. Where did you get your information about the P-38J/L Allison engines being cleared for 75"Hg? I have put together a quick reference operational timeline for the Lockheed P-38 and would like to add this information if applicable.

Jeff.

Here it is: pdf

 

[CORSNING]

Thank you Tomo. I was aware of the recommendation of the 75"Hg boosting for the P-38's Allisons, but I have not seen any military clearance actually issued or its use in combat.

Jeff.

 

[Vincenzo]

they talking of preliminary test so i suspect there were other tests

 

[CORSNING]

I am sure that there probably were. The results and follow up action is what is important.

 

[kool kitty89]

The P-51A will have significantly less power down low than the Merlin P-51, especially if the V-1650-7 is on board. 200 HP deficit vs. V-1650-3, 300 HP vs. -7, all for WER on 100/130 grade fuel.
P-39N was capable for some 385 mph on WER, with wing guns. The P-39Q, with WER power setting, was capable for around 400 mph when gun pods were not installed. Engine of the P-39Q have had another 1000 ft greater FTH than the engine on P-39N, due to removal of backfire screens (that was possible once the redesigned cylinder air intake was installed).

The P-51A was still notably lighter than the B/C or especially D. But my comments were more towards potential out of spec overboosting beyond Allison's 57" limit. (though this may have been a genuine hard limit compared to the 60" on the 8.8 supercharger engines ... let alone the earlier 54" or 44" boost)

That said, even if the boost limit was raised, at V-1 interception heights, the low-alt V-1710s probably fared better anyway.

Kool Kitty89,
Thank you. Where did you get your information about the P-38J/L Allison engines being cleared for 75"Hg? I have put together a quick reference operational timeline for the Lockheed P-38 and would like to add this information if applicable.

P-38 Performance Tests
http://www.wwiiaircraftperformance.org/p-38/Allison_V-1710-91_ENG-57-531-267.pdf

Though that document is a reccommendation following approval tests, not formal/official clearance for the P-38. The testing showed satisfactory results at 75" boost with 104/150 grade fuel, resulting in 2000 BHP output.

I don't see any performance data for the P-38J/L at that power though, highest on that page is 70" and data there is limited.