BeechTalk - BT - A “Civilian” P-38

Username Protected · **Posted:** 22 Feb 2019, 07:56

Who knows why I say that?

What unusual feature does this airplane share with the P-38?

Now, be specific.

Bonus points if you know the reason.

Username Protected · **Posted:** 22 Feb 2019, 07:59

Outward counter rotating propellers.

Username Protected · **Posted:** 22 Feb 2019, 08:02

Excellent!

Now, the thinking behind it?

Username Protected · **Posted:** 22 Feb 2019, 08:10

I don't know why but it goes faster. I asume that is the same reason some Aerostars have them.

Username Protected · **Posted:** 22 Feb 2019, 08:16

Nope.

This might require “critical “ thinking...

Maybe “torque “ your mind a bit...

Username Protected · **Posted:** 22 Feb 2019, 08:18

Supposed to have better longitudinal stability, at the expense of OEI handling.

Username Protected · **Posted:** 22 Feb 2019, 08:23

Not the reason I've read.
And the reason I've read makes sense to me...

Username Protected · **Posted:** 22 Feb 2019, 08:32

Does the Aerostar have it for the same reason?

Username Protected · **Posted:** 22 Feb 2019, 08:55

The prototype P-38, and maybe some of the first production models did not have counter rotating props. Both engines spun the same way.

The reason for outward counter rotating props I read was that in the event of an engine out, the torque of the running engine "lifted", or helped keep the airplane level in single engine flight.

Username Protected · **Posted:** 22 Feb 2019, 09:19

There are several reason why counter-rotating props are preferred vs havig a “critical” left engine. Every multi pilot gets this beat in their head during training.

The main reason is the counter-rotating prop keeps the centerline of thrust close to the fuselage while a standard rotation right engine’s centerline of thrust is outboard of the nacelle. That means if you lose the left “critical” engine that remaining thrust has a longer lever to yaw the plane.

https://www.skybrary.aero/index.php/Critical_Engine

Username Protected · **Posted:** 22 Feb 2019, 09:21

Yes, but the difference is which way they counter rotate.
Inward vs outward.

Username Protected · **Posted:** 22 Feb 2019, 09:28

Username Protected wrote:

Yes, but the difference is which way they counter rotate.
Inward vs outward.

That issue discussed in this thread. Dual- critical engines.

viewtopic.php?p=1930865#p1930865

Username Protected · **Posted:** 22 Feb 2019, 09:29

Username Protected wrote:

The prototype P-38, and maybe some of the first production models did not have counter rotating props. Both engines spun the same way.

The reason for outward counter rotating props I read was that in the event of an engine out, the torque of the running engine "lifted", or helped keep the airplane level in single engine flight.

I don't think so, the torque applied to the airframe would push down on the inboard section of the wing, loading the dead engine wing more.

Username Protected · **Posted:** 22 Feb 2019, 09:33

Username Protected wrote:

The prototype P-38, and maybe some of the first production models did not have counter rotating props. Both engines spun the same way.

The reason for outward counter rotating props I read was that in the event of an engine out, the torque of the running engine "lifted", or helped keep the airplane level in single engine flight.

Early P-38s had the counter rotating engines. They were mounted opposite what it is today.
They found it couldn’t fly off the ground in the required length of runway. In the course of, What are we gonna do about, discussions someone suggested switching engine positions.
They did that and it improved its takeoff performance.

The British were interested in the P-38. However the Gov decided it didn’t want the Brits to have Turbochargers nor the Left Turning Engine/Prop. So they made some with both engines going the same way as well as no Turbos. Brits said no thanks and the few built were used in the US in a training role.

Username Protected · **Posted:** 22 Feb 2019, 09:37

Username Protected wrote:

Early P-38s had the counter rotating engines. They were mounted opposite what it is today.
They found it couldn’t fly off the ground in the required length of runway. In the course of, What are we gonna do about, discussions someone suggested switching engine positions.
They did that and it improved its takeoff performance.

The British were interested in the P-38. However the Gov decided it didn’t want the Brits to have Turbochargers nor the Left Turning Engine/Prop. So they made some with both engines going the same way as well as no Turbos. Brits said no thanks and the few built were used in the US in a training role.

Do you have a link for the runway performance info Rich?