Prop Rotation

General discussion for CFS2 - WW 2 Pacific Theater

Prop Rotation

Postby investdude » Thu Aug 11, 2016 10:13 pm

Does anyone know how to change the rotation direction of the prop in CFS2 planes? American engines prop rotates clockwise (viewed from the pilot's seat) while British engines prop rotates counter-clockwise. I have several Spitfires, some are correct (counter-clockwise) and some are not. This affects the direction the nose swings on take-off with power application. I have examined the air file but found nothing obvious.
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Re: Prop Rotation

Postby Hagar » Fri Aug 12, 2016 1:30 am

It's a long time since I messed around with this stuff. Try this.

In Aircraft.cfg add this line under the [propeller] header.

rotation= -1

The negative value should give you counter-clockwise rotation as viewed from the cockpit.

American engines prop rotates clockwise (viewed from the pilot's seat) while British engines prop rotates counter-clockwise.

This is not always the case. Bear in mind that the prop on Merlin engined Spitfires rotates in the CFS2 default direction, clockwise as viewed from the cockpit. The Griffon rotates in the opposite direction which caused a number of accidents, especially on later marks of Seafire.
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Re: Prop Rotation

Postby investdude » Fri Aug 26, 2016 2:12 pm

First of all, I did some research and found that, as usual, Hagar is right! It was apparently universal originally that all props everywhere rotated clockwise. But when the British were developing very high powered engines for single engine naval fighters during WW2 it was found that the clockwise rotation, in the event of a bolter on a carrier landing, caused the ensuing torque to cause the aircraft to veer to the right, towards the island. So it was decided to adopt anti-clockwise rotation so that the torque would operate in the opposite direction, away from the island. Something else came into it about the need to have different engines of a similar power be able to be fitted in the same airframe. How the direction of rotation came into that I don't quite understand, but the end result was engines such as the Gypsy Major 10 in the Canadian Chipmunk DHC-1B2 rotating counter-clockwise.

Anyway, I tried Hagar's suggestion with a Spitfire and a Hurricane and added "rotation= -1" under the [propeller] header in the Aircraft.cfg file as an experiment and it worked, changing the rotation from clockwise to anti-clockwise. However, when I tried that with the Garwood Lancaster I have, which has anti-clockwise rotating Merlin engines, which should of course rotate clockwise, whether I used rotation= 1 or rotation= -1, the aircraft, although engines were off, began to spin around and blew up. Not sure if it being a multi-engine aircraft had anything to do with that.

So I'm happy that my Merlin engined fighters are rotating in the correct direction but don't know what to do about the Lancaster. By the way, I viewed some WW2 films of Spitfires and Lancasters starting up and verified that the rotation was definitely clockwise.
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Re: Prop Rotation

Postby Hagar » Fri Aug 26, 2016 3:55 pm

investdude wrote:First of all, I did some research and found that, as usual, Hagar is right! It was apparently universal originally that all props everywhere rotated clockwise. But when the British were developing very high powered engines for single engine naval fighters during WW2 it was found that the clockwise rotation, in the event of a bolter on a carrier landing, caused the ensuing torque to cause the aircraft to veer to the right, towards the island. So it was decided to adopt anti-clockwise rotation so that the torque would operate in the opposite direction, away from the island.

Anyway, I tried Hagar's suggestion with a Spitfire and a Hurricane and added "rotation= -1" under the [propeller] header in the Aircraft.cfg file as an experiment and it worked, changing the rotation from clockwise to anti-clockwise.

Not sure about the reason for direction of rotation :think: but anyway, I'm glad my suggestion worked.

However, when I tried that with the Garwood Lancaster I have, which has anti-clockwise rotating Merlin engines, which should of course rotate clockwise, whether I used rotation= 1 or rotation= -1, the aircraft, although engines were off, began to spin around and blew up. Not sure if it being a multi-engine aircraft had anything to do with that.

So I'm happy that my Merlin engined fighters are rotating in the correct direction but don't know what to do about the Lancaster. By the way, I viewed some WW2 films of Spitfires and Lancasters starting up and verified that the rotation was definitely clockwise.

For multi-engined aircraft you need a value for each engine. This allows aircraft like the P-38 Lightning to have counter-rotating props which rotate in opposite directions. https://en.wikipedia.org/wiki/Counter-rotating_propellers

For the Lanc please try this:

[propeller]
rotation= -1, -1, -1, -1
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Re: Prop Rotation

Postby papituwall » Fri Aug 26, 2016 4:04 pm

Important: Take into account that the RR Griffon had "left hand tractor drive" instead of the Merlin right hand tractor drive. This caused some confusion to Spitfire pilots upgrading to Griffon Spit Marks.
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Re: Prop Rotation

Postby papituwall » Sat Aug 27, 2016 12:10 am

You should chech your Spitfires as said before, because they can be correct.
I think a developer of an addond knows this difference.
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Re: Prop Rotation

Postby Hagar » Sat Aug 27, 2016 5:20 am

papituwall wrote:Important: Take into account that the RR Griffon had "left hand tractor drive" instead of the Merlin right hand tractor drive. This caused some confusion to Spitfire pilots upgrading to Griffon Spit Marks.

Thanks. I had already pointed this out in my first reply.

You should chech your Spitfires as said before, because they can be correct.
I think a developer of an addond knows this difference.

Not always. For example: The props on Dave Garwood's Lancaster that investdude mentioned do in fact rotate the wrong way.
While the CFG tweak I posted earlier will fix this it does not correct the P-factor effect for some reason. I'm still trying to figure this out.
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Re: Prop Rotation

Postby papituwall » Sat Aug 27, 2016 6:32 am

Thanks Hagar for your infos.
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Re: Prop Rotation

Postby Hagar » Sat Aug 27, 2016 2:47 pm

Hagar wrote:The props on Dave Garwood's Lancaster that investdude mentioned do in fact rotate the wrong way.
While the CFG tweak I posted earlier will fix this it does not correct the P-factor effect for some reason. I'm still trying to figure this out.

OK. I figured it out. Forget the rotation= line in this case.

Below the [fltsim.0] header you will see this entry;

prop_anim_ratio=-1.76

Change the negative value to positive like this;

prop_anim_ratio= 1.76

That's it! All should now work correctly. 8-)
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Re: Prop Rotation

Postby investdude » Sun Aug 28, 2016 4:26 pm

Yes, it works. Thanks again Hagar!
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