P-61 Endurance

[Zipper730]

I remember it being said that the P-61 was designed to loiter over a city for eight hours at night to guard against bomber attack. From what I remember the idea was proposed by one of the following

1. The RAF
2. General Delos Emmons
3. Jack Northrop
4. Somebody who worked under Jack Northrop

I'm curious if the prototype, or the P-61A/B could loiter for that amount of time, and if not, how long could they loiter for?

 

[fubar57]

According to Warbird Tech, Northrop was contacted to build a "....night fighter that would be an effective defensive deterrent...." by the USAAC. No name yet

 

[Night Fighter Nut]

My understanding of that bird was that it could loiter for the 8 hours. I'll have to check my references to be sure.

 

[fubar57]

One of the 14 major problems with the YP-61 and listed as number one was, "Lack of sufficient gas supply for required lengthy night patrols."

 

[Zipper730]

According to Warbird Tech, Northrop was contacted to build a "....night fighter that would be an effective defensive deterrent...." by the USAAC. No name yet

Warbird Tech Series: Volume 15: Northrop P-61 Black Widow, by Warren E. Thompson.

That said, I distinctly remember other sources talking about a night fighter that could loiter over a city a whole night (8 hrs).

One of the 14 major problems with the YP-61 and listed as number one was, "Lack of sufficient gas supply for required lengthy night patrols."

So that answers that.

Does anybody know how long it could loiter?

 

[fubar57]

Another book says three of the above or below...

1. The RAF
2. General Delos Emmons
3. Jack Northrop

....so it depends on the book/s

 

[pbehn]

Finding crews who could loiter for 8 hrs regularly and effectively would probably be a challenge.

 

[pinehilljoe]

I'll try and dig through my old Wing/Airpower. They did a multi part article on the P-61.

 

[Dana Bell]

The original spec called for a 2-hour endurance at full throttle; I hope to be copying the original flight test results later this week...

Cheers,


Dana

 

[Night Fighter Nut]

It all really depends on engine type, prop type, altitude, and aircraft weight.

Xp-61, 1465 miles at 200 mph at 10k alt. About 7 hours. R-2800-10 engine, Curtiss 12-22 prop.
P-61A, 2225 miles at 221 mph at 10k alt. About 10 hours. R-2800-65 engine, Curtiss 12-22 prop.

You change altitude and speed you'll have a different number. More later.

 

[Zipper730]

Finding crews who could loiter for 8 hrs regularly and effectively would probably be a challenge.

How long were typical P-51 escort missions?

It all really depends on engine type, prop type, altitude, and aircraft weight.

Xp-61, 1465 miles at 200 mph at 10k alt. About 7 hours. R-2800-10 engine, Curtiss 12-22 prop.

P-61A, 2225 miles at 221 mph at 10k alt. About 10 hours. R-2800-65 engine, Curtiss 12-22 prop.

Those figures don't look all that bad, that said...

1. What weight are we seeing on these flights?
2. Is this endurance time based upon takeoff to landing, or simply once on station?
3. Does this include the provision for combat, or the need to divert to another air-field, or loiter for landing?

 

[pbehn]

How long were typical P-51 escort missions?

I think six hours at longest in Europe, I wasn't thinking of the flying but looking at a CRT for 8 hrs, it is hypnotic.

 

[Zipper730]

I think six hours at longest in Europe, I wasn't thinking of the flying but looking at a CRT for 8 hrs, it is hypnotic.

Didn't think of that. Good point.

If two hours at full throttle were a goal, would the turbocharger have been a better choice?

 

[Night Fighter Nut]

Those flights would have to be under standard configuration and weights. Not taking getting up to altitude or current weather situation into account. This can really only be calculated. Not taking air density, or weither or not the pilot is suffering from the Hershey squirts for consideration. FAA has what is known as a standard day. Unfortunately it is not often the conditions for a standard day are actually met.

 

[pbehn]

Didn't think of that. Good point.

?

I used to do ultrasonics which is looking at a CRT and also looked at radiographs, if you do it continuously you start missing things.

 

[MIflyer]

When they tested the P-38M they found its range was about the same as a P-61, which in the Pacific was considered to be too short. For ferry missions in the Pacific P-61's were equipped with extra tanks that occupied the area where the turret had been located.

Admittedly, for loiter you can pull back the throttles and just kind of hang in the air.

 

[Zipper730]

Does anybody have any of the followng

1. A P-61 flight manual
2. Data on the P-61's weights
3. Information on air temperature differences across different parts of the world (I remember seeing some kind of graph based on WWII conditions, it looked like a series of curvy lines which depicted temperature at different altitudes changing across the different areas of the globe)?
4. A power-curve of the P-61 level flight and climb-trials

 

[fubar57]

Flight manual in the Other Mechanical Systems Tech. section

 

[P-39 Expert]

Similar R-2800 in a Hellcat burned 250gallons/hr at normal power at altitude.

 

[Dana Bell]

I finally found a note I copied at the National Archives yesterday. On Christmas Day 1944, the Northrop rep embedded with the Fifth Service Command reported:

The ships with the extra gas tanks have just enough range for a good combat mission now.

Considering that the P-61 lacked endurance, speed, and altitude, any improvement with one reduced the effectiveness of the others. "Just enough" isn't a ringing endorsement, and drop tanks further reduced speed and altitude...

Cheers,


Dana