P-38 Lighting

[Nick2024]

Instructor and I was talking and could not reason why the P-38 has two critical engines. Anyone on here have insight on this?

 

[darrenf]

Copied from another forum.....

Warren M. Bodie, in his book The Lockheed P-38 Lightning: The Definitive Story Of Lockheed's P-38 Fighter, states that, "Engine rotation was changed so that the propellers rotated outboard (at the top), thereby eliminating or at least reducing the downwash onto the wing centersection/fuselage juncture. There was, by then, no doubt that the disturbed airflow, trapped between the two booms, was having an adverse effect on the horizontal stabilizer. No problem was encountered in reversing propeller rotation direction; they merely had to interchange the left and right engines."

http://www.ww2aircraft.net/forum/technical/why-propellers-p-38-lightning-rotate-outwards-10566.html

 

[ftyflyboy]

Both cannot be critical. One has to more adversely effect the performance of the aircraft to be considered "critical"

 

[Orange Anchor]

Don't know about 'critical' but my old fiend and WWII P-38 ace, Kirby, said he never forgot seeing all the Allison -1710s stacked up at his airfield. I had asked what speed he used to get airborne and he told me that he just waited until he was almost out of runway and then he lifted off. Engines routinely were pulled with less than 50hrs on them.

 

[Blip16]

Both cannot be critical. One has to more adversely effect the performance of the aircraft to be considered "critical"

in this case they can be, because an engine failure on either side would have the same affects as your book definition critical engine. (assuming I read the quote correctly at 445am)

 

[Nick2024]

Thanks for the input guys, I do remember reading somewhere about the downwash getting stuck between the booms . Thanks!

 

[Landis]

in this case they can be, because an engine failure on either side would have the same affects as your book definition critical engine. (assuming I read the quote correctly at 445am)

The critical engine is the one that MOST adversely affects control. In this case losing either one would suck something fierce, but losing either one would EQUALLY suck.

 

[tgrayson]

The critical engine is the one that MOST adversely affects control. In this case losing either one would suck something fierce, but losing either one would EQUALLY suck.

Agreed. Saying both engines are critical indicates a misunderstanding of what "critical" means. Perhaps both engines on our Seneca are critical because there is a greater yaw with the 200 hp engines than there would be if they were only 150 hp?

 

[Minuteman]

Don't know about 'critical' but my old fiend and WWII P-38 ace, Kirby, said he never forgot seeing all the Allison -1710s stacked up at his airfield.

That tradition is apparently being continued by Fantasy of Flight in Florida.

​

I also found this picture when reading about he Allison 1710.

​

All engines on the XB-38 appear to rotate in the same direction (the same as the radial setup). Wikipedia says,

While the XB-38 delivered a slightly higher top speed, after a few flights it had to be grounded due to a problem with engine manifold joints leaking exhaust gases. Following the fixing of this problem, testing continued until the ninth flight on June 16, 1943. During this flight, the third (right inboard) engine caught fire, and the crew was forced to bail out. The XB-38 was destroyed and the project was canceled, in part because the V-1710 engines were needed for other projects such as the P-38 Lightning, P-39 Airacobra, P-40 Warhawk, P-51A Mustang and P-63 Kingcobra fighter aircraft.

I wonder if they used the same trick as the P-51 where the variable exhaust vent from the radiator could be set just right to expand the heated air and act like a small jet engine (the exhaust pressure was higher than the stagnation pressure at the inlet).

 

[Milesar]

XB-38
Now that is awesome.

 

[ryan1234]

Agreed. Saying both engines are critical indicates a misunderstanding of what "critical" means. Perhaps both engines on our Seneca are critical because there is a greater yaw with the 200 hp engines than there would be if they were only 150 hp?

I was talking to an old-timer about it, a former Lightning pilot, in his training on multi-engine emergencies with the P-38 - he mentioned they called it "critical torque" on both engines - and that's possibly where the "critical engine" thing came from.

 

[Mike H]

Found a cool youtube on the p-38 almost 35 minutes long, though, so bring a snickers bar

[YT]MgxEwTBOoR8[/YT]