P-61 Endurance

Vincenzo said:

230 mph don't look as max cruise, is possible that 91 was for each engine?

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230 mph TAS was the most fuel-efficient cruise setting listed in the charts for 15,000 feet; there were no entries for higher altitudes in Column IV. The Maximum Range (Column V) section had no entries. Bumping the cruise speed up to 240 TAS at 15,000 feet consumed 180 gallons per hour (Column III); at 270 TAS, fuel consumption was 230 gallons per hour (Column II).

The important factor is that these are preliminary figures, and had yet to be flight checked. If anyone has a PFOI for the P-61 which has the flight-checked figures, then please do post the cruise figures from it.

I've on the hard disk a 7/45 PFOI it report, for the max cruise, the 91 gph at 35.5 low gear 18k feet with the -10&-65 engine variant
idk if USAAF in this table for twin engined fighter report each engine consume or for both

You are correct. 60 to 91 gallons per hour per engine, depending on cruise power. So, that takes us to about 2.5 - 3.2 hours endurance, on internal fuel alone, assuming a 1/2 hour fuel reserve. Combat time significantly reduces that time.

It would appear that the 2-hour max-continuous requirement didn't supersede the 8-hour time on station requirement, but was added onto the design (which is to say that the aircraft would have to either do 8-hours at loitering settings, or race along for 2-hours at MCP).

I'm curious on this note what the typical loiter times and ranges were seen by other night-fighters used?

At this point in time I'm pretty sure the Bristol Blenheim, Bristol Beaufighter, Douglas Havoc I/II, and Boulton Paul Defiant were used by the RAF; the Luftwaffe using the Junkers Ju 88, Messerschmitt Bf 110, and the Dornier Do 17.

According to the POH at sea level for maximum cruise you have 77 GPH at 34 inches manifold pressure, with the supercharger in Neutral. That is the lowest fuel consumption they show. At 30,000 ft with the superchargers in High it is 87 GPH.