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Author Topic: P-38  (Read 2348 times)

Offline MachFly

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P-38
« on: November 05, 2011, 10:48:24 PM »
I know P-38 has counter rotating props, but is it just the props or are the engines counter rotating as well?


Thanks
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Offline colmbo

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Re: P-38
« Reply #1 on: November 05, 2011, 11:20:10 PM »
It was equipped with "handed" engines....the engines turned opposite directions.
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Offline Oldman731

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Re: P-38
« Reply #2 on: November 06, 2011, 01:30:05 AM »
Quote from: colmbo on November 05, 2011, 11:20:10 PM
It was equipped with "handed" engines....the engines turned opposite directions.

One of the reasons it was so expensive.

- oldman
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Offline MachFly

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Re: P-38
« Reply #3 on: November 06, 2011, 01:38:20 AM »
Thanks for clarifying
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"Now, if I had to make the choice of one fighter aircraft above all the others...it would be, without any doubt, the world's greatest propeller driven flying machine - the magnificent and immortal Spitfire."
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Offline Wagger

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Re: P-38
« Reply #4 on: November 06, 2011, 01:57:29 AM »
Is it the engines turned in opposite directions or just the camshafts?  I know some WWI fighters had engines that rotated but thought all WWII radial engines and inline ingines were stationary with the exception of the camshaft/drive shaft.
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Offline MAINER

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Re: P-38
« Reply #5 on: November 06, 2011, 06:56:21 AM »
I always thought that on a P-38 the left engine had a gear box on it to change the direction...
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Offline colmbo

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Re: P-38
« Reply #6 on: November 06, 2011, 08:36:48 AM »
Quote from: Wagger on November 06, 2011, 01:57:29 AM
Is it the engines turned in opposite directions or just the camshafts?  I know some WWI fighters had engines that rotated but thought all WWII radial engines and inline ingines were stationary with the exception of the camshaft/drive shaft.


Wiseguy!  :D

It's the crank that turns opposite direction.
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Offline colmbo

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Re: P-38
« Reply #7 on: November 06, 2011, 08:39:41 AM »
From Wiki with reference from "Americas Hundred Thousand"

Quote
Counter-rotation was achieved with the use of "handed" engines, which meant that the crankshaft of each engine turned in the opposite direction of its counterpart. The V-12 engines only required that the spark plug firing order be changed in order for the direction of the crank shaft to be reversed, according to the General Motors Allison V1710 Service School Handbook.
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Offline MiloMorai

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Re: P-38
« Reply #8 on: November 06, 2011, 10:03:34 AM »
One can download the service manual from https://rs232tl.rapidshare.com/#!download|232tl4|391852386|Allison_Service_Handbook.pdf|115839|R~704745CD4DF5F414BF8532BE3FDEDE50|0|0

There was an extra gear installed to get the cam shafts to rotate the same direction in the right and left engines.
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Offline MiloMorai

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Re: P-38
« Reply #9 on: November 07, 2011, 02:38:32 PM »
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Offline icepac

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Re: P-38
« Reply #10 on: November 08, 2011, 08:37:22 AM »
Quote from: MiloMorai on November 06, 2011, 10:03:34 AM
One can download the service manual from https://rs232tl.rapidshare.com/#!download|232tl4|391852386|Allison_Service_Handbook.pdf|115839|R~704745CD4DF5F414BF8532BE3FDEDE50|0|0

There was an extra gear installed to get the cam shafts to rotate the same direction in the right and left engines.

Been there.....seen the setup that allows reverse rotation.

There are many other engine peripherals that also need changing.

Most obvious is the starter but many accessory driven devices need to be tailored for reverse rotation or they won't work such as prop governers and oil pumps.
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Offline morfiend

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Re: P-38
« Reply #11 on: November 08, 2011, 06:15:26 PM »
Quote from: icepac on November 08, 2011, 08:37:22 AM
Been there.....seen the setup that allows reverse rotation.

There are many other engine peripherals that also need changing.

Most obvious is the starter but many accessory driven devices need to be tailored for reverse rotation or they won't work such as prop governers and oil pumps.

 This is the main reason why many twins weren't built with counterrotating props.  The logistics involved became too much and too expensive.  This is also why the P38 is such a unique aircraft.




   :salute
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Offline Captain Virgil Hilts

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Re: P-38
« Reply #12 on: November 09, 2011, 10:19:45 AM »
The Allison V-1710 was designed from the beginning to run in either direction. You change an Allison from a left hand engine to a right hand engine mostly by how you assemble it, not by changing a great number of parts.

The gearbox is changed because when spun the other direction, the direction of thrust changes as well.

The gear box is really the only major difference, and did not increase the cost of the Allison that much.

The Lightning was expensive because it was very complex, and required special fixturing and close tolerance assembly. Steve Hinton once said it was one of the most elegant and exotic designs of the era.
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Offline icepac

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Re: P-38
« Reply #13 on: November 10, 2011, 08:03:42 AM »
On a V1710, you have to change oil pump or it's drive, prop governor and it's drive, camshaft, timing advance mechanisms, supercharger drive or impellers, and the rest of the accessory drives...........or........yo u can just make a gear case that turns the prop in the opposite direction like we do in boats.
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Offline Pigslilspaz

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Re: P-38
« Reply #14 on: November 15, 2011, 02:30:59 AM »
Question, weren't the lend lease versions fitted with props going in the same direction?
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