I need a big engine [Archive] - Radio Control Zone

teaminfinity

01-21-2006, 01:24 PM

I am designing a rc airboat, for those of you who don't know what it is, its a hull with an airplane engine and a fan on it. I am making a haigh speed one, and want to obtain speeds of 30mph, this is not going to be easy and will require a big engine, as it is not the most efficient method of propulsion.

So, i thought I would as you rc airplane experts to help me find a powerfulll motor. Should I go for high HP's or high RPM? Ive been looking at the engine market and have found there are quite a few.

Should I go for a 4 stroke gas, a 4 stroke nitro, a 2 stroke gas, 2 stroke nitro, and what displacement?

I dont really want to spent more then $200, this may seem like a challenge, hope you can help!

cheers

Cub lover

01-21-2006, 05:05 PM

Firts of all, what size are you planning on this thing being?

bigedmustafa

01-21-2006, 11:13 PM

The Hobbico Aquacraft Air Force sounds similar in concept to what you might be thinking about:

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXBTC1**&P=0

This boat runs off a typical .46 cu in airplane motor. A two-stroke .46 cu in airplane motor can be had for $65 to $130 depending upon the brand in question.

Dumas also makes a number of airboat kits:

http://www.towerhobbies.com/listings/cat-cat-b.html

How you prop the engine may have as much impact on your top speed as what engine you use. You might want to try a variety of propellers such as 10x7, 11x6, and maybe even a 9x7 3-bladed prop to see which one gives you the best results.

The kit you're building will determine the size of engine you can use. 4-stroke engines spin at lower maximum RPMs than 2-strokes, but can turn a larger prop. In addition to being more expensive than 2-stroke engines, 4-stroke engines are also heavier. You may be able to swing a big prop from a 4-stroke, or you may not have the prop clearance to take advantage of a 4-stroke, or a 4-stroke may throw off the boat's balance to the point of being unusable.

If you can provide specifics about your boat, perhaps more suggestions could be made. Good luck.