RK Racing

well i have never built an airboat before so dont know if it will work or not


















let me know what you guys think

rickburnout666

Looks good and strong [sm=thumbup.gif], have you got the engine mounts worked out yet?

RK Racing

not yet i dont know what size the motor will be or the prop size

rickburnout666

What is the size of the boat ? that will help you work out what size engine to use, and you will then know what props you could use.
Have you built any other type of R/C models before or is this first go?

RK Racing

the boat is 24'' x 12''

and this is my first build all my other boats are rtr or almost ready

rickburnout666

for that size of boat i would use a .40 - .50 glow engine, running with a puller prop

RK Racing

how long are the props on a 50 and how far from the rear of the hull does the prop need

sorry about all the ?s but i dont know anything about airboats

RK Racing

Tommy gallagher

The pic before the last one shows a little of the underside. I suggest sanding it very well it looks like the wood seams dont join together and flow together to well. But sure is sturdy. How tall is the hull itself.

RK Racing

thats what im doing tonight is sanding it down and geting ready for fiberglass its 2.5'' tall

asmithnc

Great work so far. Looks like you have put a lot of thought in the design and your cuts are clean. If you are looking for a power plant I would go with a OS .46 ax. It's a strong cheap motor that will have more power than you need. Props for this engine range from 10" to 11".

Airboats can be very tricky even if it's your 10th build. Sometime you get it right......... other time they suck. Keep a positive mind set and get ready to build another, even if it's great.

RK Racing

thanks man this is all new to me i need all the help i can get i still dont know how im going to do the rudder

and also what are my options on where to mount the fuel tank

RK Racing

starting to add some foam

rickburnout666

is that expanding foam, from a can ?

RK Racing

yes

rickburnout666

Some types of expanding foam, have been known to blow boats apart, it looks like it is cured/set, and then much later it expands some more, and BANG it can make a mess of your hard work and pride and joy, [:@]

RK Racing

it said on the can 10 hr to fully cure when i trimed it to be level with the top of the hull it was still wet in the middle and then nit expaned some more when i trimed it this time it seams to b done it will be another week before i put the deck on so hopfuly if its gonna happen it will by then

asmithnc

Be very careful with expanded foam. Once cut or sanded you open the pores and it will hold water like a sponge. Be sure to put a layer of resin to seal the foam before you put the deck on. Fuel tank.... your choice..... I would put it in the hull.

rickburnout666

What the cans say, and the truth are somewhat different [&:] , it also soaks up water, its made for building use, not model building, There are more posts on RCU and other sites, You can find more, if you put foam or expanding foam in the search. its been used in many different models and caused a lot of trouble for some people.

Heres another post about it.

Hydro Junkie -> RE: My attempt at the "international woody" 49in (3/23/2007 3:52:16 AM)
The problem with the foam is that it tends to blow boats apart. A totally enclosed area like you have will act like and oven. This has the affect of making the foam expand, Since there is no place for the foam and hot air to expand to, it will split the seams and destroy the boat. All it takes is the boat be left in the sun a few times and "BOOM" [X(][&o]

RK Racing

that sucks i guess now i know for the next one

rickburnout666

perhaps you could cut a hole out of the middle of the foam so if it does expand more, it will expand inwards and not blow the boat apart[sm=confused.gif] or thake it all out and use polystyrene foam blocks, cut to size.They work well, and dont expand or soak up water

RK Racing

i think i will give it some room to expand

how big does the rudder need to be

rickburnout666

The rudder or rudders i usualy use are as tall as the props length and 2 1/2 inches wide, i prefer to use 2 rudders, as i think it looks better than one.

RK Racing

thanks for the info how fast is that boat in the pic

rickburnout666

The boat in the picture is still not finished, i`ve had to put the build on hold for now, because i got knocked of my daughters race bike, and i broke my coller bone for the 4th time,[:@] so im just trying to take things easy, but i cant sit still for too long, so it should be finished soon,
Heres the thread on the build

http://www.rcuniverse.com/forum/m_5220872/tm.htm