Hello,

I read about some planes saying to have a minimum spacing between backplate and cowl. Also, other planes like yaks saying 1/2 inch and some say 1 inch spacing.

Is there a general guide for spacing backplate to cowl?

Thanks in advance for your help.

There is no general guide , but there is a ton of experienced builders and pilots that can offer help ..
What kind of plane ?

Whatever looks good and doesn't rub.

I always shoot for no more than 1/8"

For extras or edges pretty much any plane with a nose ring about 1/8 "is good depending on size of the plane and if you need to add any thrust angles to it. On a yak or sukhoi round cowl you want to get the prop as far forward as possible.

Originally Posted by dusturbd

I always shoot for no more than 1/8"

like on the Extreme flight yak V2, as i remember it says in the manual 1 inch spacing is what is recommended. Not sure why.

Originally Posted by Surfer Dude

For extras or edges pretty much any plane with a nose ring about 1/8 "is good depending on size of the plane and if you need to add any thrust angles to it. On a yak or sukhoi round cowl you want to get the prop as far forward as possible.

Hello,

Thanks for the response, why on the round cowls do you need more spacing?

Efficiency and thrust. Some claim they cant tell the difference but if you look at videos of Quique flying in the last TOC with his yak that was 42 lbs I think on a 3w 150 on cans his engine was pushed out as far as possible. Back in those days you did everything you could to get any sort of extra power.