prop efficiency and radial engines
02-10-2007 | 11:59 AM
#1
Thread Starter
prop efficiency and radial engines
I'm just finishing up an AT-6 scratchbuild, and since its very light, I am confident that my little
OS .10 will pull the 40" span model.
The problem is, the little engine leaves a huge gaping mouth to catch the air, and I was
thinking of filling in at least the bottom half.
I was thinking this would cut down on overall fuselage drag, but how would this affect prop
efficiency with a flat surface right behind ?
Also, this is a handlaunch model, so I'd sure like to fill in that space so it doesnt scoop up dirt.
OS .10 will pull the 40" span model.
The problem is, the little engine leaves a huge gaping mouth to catch the air, and I was
thinking of filling in at least the bottom half.
I was thinking this would cut down on overall fuselage drag, but how would this affect prop
efficiency with a flat surface right behind ?
Also, this is a handlaunch model, so I'd sure like to fill in that space so it doesnt scoop up dirt.
02-10-2007 | 01:36 PM
#2
Senior Member
Joined: Aug 2005
Posts: 1,333
Likes: 0
Received 0 Likes
on
0 Posts
From: Austin,
TX
RE: prop efficiency and radial engines
I doubt that you will notice the difference. The lion's share of a prop's thrust is generated by the part of the prop that is outside the plane's cowling anyway.
02-10-2007 | 02:08 PM
#3
Joined: Jan 2005
Posts: 248
Likes: 0
Received 0 Likes
on
0 Posts
From: Oakville,
ON, CANADA
RE: prop efficiency and radial engines
hi west6008,
I fly .25 powered Maac Scale Combat. A couple years ago my buddy 'Iceman' built a Polikarpov I-16 at 40in. span. It had an O.S.FX with a MA 9-4 (might have been a 10-4) The cowl was 8 inches diameter ! The front was basicly a flat plate with a cutout for engine cooling from 11-1 o'clock. The back of the prop was about 1in. in front of the cowl.
Some of us thought it would never work...but it did ! It flew fine. Obviously not at fast as the the other WW2 fighters we fly.
He built it because it was the hardest WW2 fighter to build and fly...
You should have no problems blocking off the front of your cowl from 1-11 o'clock. Make sure you have cooling air exit holes in the back end of the cowl bigger than the intake area.
Good luck with your AT-6.
I like small handlaunched WW2 Warbirds. The 'permanent' retracts are lighter (and cheaper!) than fixed landing gear !
Take care,
Have fun,
Dave'crosscheck'Fallowfield
Maac 6437
Unabashed Combat Team
Oakville, Ont. CANADA
I fly .25 powered Maac Scale Combat. A couple years ago my buddy 'Iceman' built a Polikarpov I-16 at 40in. span. It had an O.S.FX with a MA 9-4 (might have been a 10-4) The cowl was 8 inches diameter ! The front was basicly a flat plate with a cutout for engine cooling from 11-1 o'clock. The back of the prop was about 1in. in front of the cowl.
Some of us thought it would never work...but it did ! It flew fine. Obviously not at fast as the the other WW2 fighters we fly.
He built it because it was the hardest WW2 fighter to build and fly...
You should have no problems blocking off the front of your cowl from 1-11 o'clock. Make sure you have cooling air exit holes in the back end of the cowl bigger than the intake area.
Good luck with your AT-6.
I like small handlaunched WW2 Warbirds. The 'permanent' retracts are lighter (and cheaper!) than fixed landing gear !
Take care,
Have fun,
Dave'crosscheck'Fallowfield
Maac 6437
Unabashed Combat Team
Oakville, Ont. CANADA
