Hi,
I was wondering if I had a 9" cowling on a 0.46 size model, would i lose thrust from the 10.5" prop?

My thinking is that only 1.5" of the prop is creating thrust that travels over the tail surfaces and wing.

John Murray

The greater part of the thrust is generated by the prop from half way on out to the tip. You are pushing it with a cowl that big. May work? Try and see carefully if you have a big field?

Enjoy,

Jim

My 120 sized Sukhoi has an 8" cowling, just curious as to what .46 sized plane has that large of a cowl?

Andy

It was an ESM SU-31M, it recommended a 0.46, but the prop wouldn't have even cleared the cowling.

In order to clear the cowl, I would have had to put a 0.61 Tiger Shark under the hood.

That would have been with the min pitch, max diameter prop.

I'm now looking at the Phoneix Sukhoi, and from memory, it has a small cowl, but figured I'd ask just in case.


John Murray

Sorry to not actually contribute, but 8" seems awfully large for ja .40 sized Sukhoi. I have a .40 sized Focke Wolf 190, and that's a large cowl, but it barely makes 6" across. It flies well on a .56 4 stroke, but it's not all that fast. With that much frontal area, I wonder if a .46 engine would pull the plane along fast enough to do anything.....

Andy

Hello!!!!
It seems to me very strange that size of cowl, but if it is so, maybe you shoul try a larger prop with less pitch, I have my Something Extra with a 14x4 prop and flies great.

Go to your field and try some diferent props, but be very gentle with airplane while your are flying

Have a nice day
Escipion

Interesting question and i don't know the answer. I'd thought the same thing when looking at kits of the GeeBee R2: [link=http://www.adrianpage.com/index.html]GeeBee R2[/link]

Another consideration is that our props are "tractors", that is they pull the aircraft. So, theoretically, it only matters what's in front of the prop.

Of course, there has to be some amount of space behind the prop for the air to go after it's been pulled through.
Dennis-

Which version are you looking at ?

google didn't return much about this plane, but it appears that there is a 40-60 size and a 120 size....

which size has the 9" cowl?

Another question occurs to me -- why use a 10.5" dia prop -- a 12-4 works very well on a BB .46 (it's too much for an OS .46 LA).

I use 11.6 & 11.7s on some of my 46's and they work great. A 9" cowl for a 40 size plane ????? my Beaver has a round cowl and it is 6" and an 11.7 works good on an OS 46.