small 4cell w/hp low turn motor?

[HyperBaja]

hi everyone, i have 3 boats as of now, a Dumas scarab S (30cc homelite) a 28" swamp buggy and a great planes wildcat (twin 550 w/ 12cells) and i am wondering has anyone done any 4 cell racing? would anyone know of a good hull less than 2 inches, preferably a catamaran.
thanks,
tommy

[FrankW]

2 inches long? That would be pretty small. Did you mean 20 inches? There are quite a few 4 cell racers, like Trent Hare. You might wanna check out the forums at www.rumrunnerracing.com to find info. A good 4 cell hull would be a small catameran with a balsa hull and foam sponsons. A 3-point might be good if you can keep the rear end off the water. Maybe a canard would work well.

There's not many hulls available designed for 4 cell racing, since it's a fairly new class and there's still a lot of experimenting being done. A good hull might be the Jay Turner designed XL Cat (available through the RC store (http://www.rcstore.com/) ). It is 18 inches long and should perform well with 4 cells. You could reduce the plans a little, but you will have to watch out for instability if you make the boat smaller.

You might be able to get away with reducing the plans for Jay Turner's Yellow Jacker outrigger (also available through the R/C store). It's ment for 6 cells stock racing. You might be able to run it as is, but I would shorten the hull a little if I could.

-Frank

[RS4rally1124]

hey Frank i also want to build a 4 cell but it has to be a cat. i would like to hit close to thirty like the quickie cat did if you have thAT issue. how do i build the sponsons. i have tride and i have never gotten it to work. i need

materials
basics dezines.


thank
JT

[FrankW]

30 mph on 4 cells is quite a goal... many 6 cell cats can't even do 30 mph. I'm betting that it's not your design that's not working, but it's your set-up. For 30 mph you would need the boat to have a SAW (straitaway) like set-up... meaning a very high pitched prop, lots of amp draw and very little run time. You can expect to draw 40 to 50 amps in 4 cell boats. Jay Turner suggests an Octura P735 prop with a 10 turn motor for his XL cat when powered by 4 cells.

For sponson material, I would suggest foam because it's like, solid and would be it's own floatation. You should put some lexan on the bottom for a ride pad.

-Frank

[RS4rally1124]

thanks frank. the 30mph isn't that bad. they had the quickie cat going 28 and 2 mph isn't that hard. the motor i will use is a speed 700 bb race motor. so i think it shall work.


JT

[FrankW]

whoa, whoa, whoa. First 2 mph is hard, especially with such limited power, and second... that motor is way to big for a 4 cell set-up. That motor is heavy and is commonly used for 12 cell racing. You would be much better off with a low turn R/C car motor.

-Frank

[RS4rally1124]

i decided you were right. i am now building a 12*7 cat that will use a airplain motor. it should be able to do 12-15 i think with the 380 size motor and 4 cells. this will be an experiance and a half. but all i care about is to beat a 100 dollar tyco boat that my neighbor has. and i think it will be more embarrasing with the little cat that my bid 10 cell deep vee racing boat.

100 dollars for a tyco lal

JT

[Andrewg]

I suggest checking www.microhydros.com

there are video plans and fast boats

the micros are generally around 15-18" and will run at 30+ mph for 4 minutes

compared to 4 cell they are a big thrill - as fast and smaller and much better runtimes