andrew fitzpatrick

im building my latest airboat its the second one ive done. i draw the plans myself then build from scratch its 48' long 15' wide and 4' hull height. it will be glow. it needs a 12 ' prop and i want a 1:1 thrust ratio
also its entirerly built of blasa anybody have any thoughts on what motor i should get for it

Apismelifera

First off, I think you mean 48 inches long, 15 inches wide, 4 inches deck height?

' equals Feet.
" equals Inches.

As in, this board is; five feet ten inches long, or, 5'10" long.

As far as engine size, what size engine can turn the 12" propeller that you're interested in, at a decent RPM?

andrew fitzpatrick

yeah sorry about the misunderstanding
i dont care at what rpm as i have never done gas befor and im only 15

Apismelifera

You have nothing to be sorry for.

After a quick search on Google I found a prop chart for four stroke glow fuel engines. If you're planning on using a two stroke glow fuel, two stroke gasoline, or four stroke gasoline, then you need to go find a different chart. You can search this site too, lots of information here if you look around a bit.

The engine manufacturers will have this info on their web sites too.

andrew fitzpatrick

yeah i was thinking 2 stroke glow bcz its cheaper
also i have a an old 32 cc 2 stroke motor frm a lawn tool that could be converted
to an rc motor easily it might be to big thougs
also thanks for help as it is appreciated

expresscraft

a .65-75 should work great, i would mount the motor pointing forward to allow tractor props, the selection is better, the motor will get more air over it and run better, the engine will not have the rudders in the way when starting, it will not look as scale but will be a better boat, get a bunch of pitch and plastic props or a apc will work well, wood will look good but will not hold up to getting hit by water a derbies, hope this helps

Altered1

Old post, but here is some info:

Airboat Forum : http://www.rcuniverse.com/forum/forumid_246/tt.htm 

Probably a better place to post these questions.

Your hull may be a bit narrow at those dimensions.

Good Luck


Wooden props are a definite no-no.