Cowling Interupting Prop
 

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

RE: Cowling Interupting Prop
 

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

RE: Cowling Interupting Prop
 

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

Andy

RE: Cowling Interupting Prop
 

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

RE: Cowling Interupting Prop
 

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

RE: Cowling Interupting Prop
 

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

RE: Cowling Interupting Prop
 

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]

RE: Cowling Interupting Prop
 

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. :D
Dennis-

RE: Cowling Interupting Prop
 

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?

RE: Cowling Interupting Prop
 

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).

RE: Cowling Interupting Prop
 

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.