Yogi-Bear

I just have completed a scratch built airboat well almost......
I constructed using my old body board i made an aluminium motor mount with twin air rudders. The radio box is on the front of the board and is a decor screwtop food container the radio mount is a piece of aluminium the servos sit on it and are bolted to the aluminum mount. Bolted right through the boat onto the motor mount are 2 surfboard type fins. This provides a strong mount for the motor and attaches the motor to the board very well.

after test running it i found i had no steering even at full throws. this is because i installed 2 surfbaord fins under the boat. the boat as a result is on rails the test run was a windy cold and wavey day (about a foot chop) i ran it full throttle it to the chop and wind and had it catching full air. It was doing about 25 km/h into the stiff breeze but on flat water i suspect it will do much better the stability though in the ruff stuffs even going side on to the waves is amazing. With the 2 fins beneath the water ill need to install water rudders but after the test i am confident that i can use the boat on those non perfect days.. it is powered by an irvine .46 and i might get a bigger motor later but in the mean while i need to construct some water rudders no pics atm ill see what i can do though........

In summary if u want a stable air boat then add 2 fins under neath with water rudders and u will have a fast boat that will be suitable for even the most inexperienced modeler and for those rougher days.

Any questions u want to ask ??

Elwood

My Feedback: (2)

How about a Pic?

Yogi-Bear

I tested the water rudders today....... its steers like a charm..... at idle so looks like ill have to get a more powerful servo..... and performance from my 46 is lacking its a big boat so i think ill go a 60 somthing see what it does....
I think im gonna take the fins of the bottom and try just air rudders should work fine...... ill post more pics when the mods have been made

Yogi-Bear

Tell me what u think about my design....

bigjdubb

It looks cool. Isnt there supposed to be a tunnel or something around the prop, kind of like a bottomless can?

Hairball

I love its simplicity. Adding a duct around the prop would look pretty cool, and you could add rudders to that to help steering as well.

Yogi-Bear

A little update after running some tests....

First i have removed the water rudders that you see that were previously attached to the air rudders leaving the old air rudders. of course this leaves the boat unsteerable so we also removed the black fins beneath the hull..... wow what a difference this thing had more speed and now slides sideways at top speed with full reverse rudder sweeeeeet now this a toy..... we estimated the boat at 30km/h as it took aprox 5 secs over 40m this is all rough and at the time of that test i was running a 10X6 well after losing the prop my bad driving..... i went to the store and bought 3 props a 10X6 a 10X7 and an 11X6.

Prop testing
went to the lake and ran the boat in less than ideal conditions (20 knot winds and small chop) with the 10X7 this produced little change to the performance maybe a slight increase in speed but barely noticable to the naked eye ..... a quick stop and restart with the 11X6 WOW an extra 10km/h it was going as fast as the other props at 3/4 throttle sweeet and the same accelration was there. the test ended with out going back to the old prop i think ill try and exchange it for 11X7, 11X8 or just a 11X6 but i tell u it makes a difference.

Inconclusion props on ur airboat just like anyboat make a difference if its like mine and a bigboat try the a prop in the "large" range of ur motors capabilitys with pitch between 6-8 from my testing it should give a nice increase in top speed and wont affect the accelartion ill report back on the tests with other 11 sized props.

Pics of the boat in the water doing 360's and running flat out straight and of what it now looks like.... (i need a speed gun )

Go to http://home.wanadoo.nl/stuipsmulders...set_index1.htm for great info on airboat construction etc...

Please comment......

rcboatscars

Hey
Love to get the info on your airboat...i am playing with a dumas gale force airboat right now and couldnt get it to turn either, and it already had a water rudder. but it also has a turn fin in the middle of the bottom of the boat, so that thing is outta here tonight!!!!! going from a doggie os 60 to a brand new os 46 la tomorrow. have put lead weights in the nose of both sponsons and that was another mistake. think i'll cut the noses of the sponsons off to save the weight. have an oversize gas tank, and i am going to junk it too. i forgot the first rule of boating....make it light, lighter, lightest!!!!!!!!! you can always add weight later if you must. JB

Yogi-Bear

more photos...

and stats....

Engine: .46 irvine

Propeller: 11X6 testing 11X7

Engine mount and rudders are made from aluminium and brass hinges attach the rudders to the mount. radio box is a screw top food container and servo tray is a peice of aluminium bent in an u shape with ledges at the top to allow bolting the servos on.

Speed: Currently 40km/h

just ask for any other stats you may need

rcboatscars

This thing looks great!!!!!
wonder how you got the engine mounted solidly. what engine did you decide on? plastic prop? like that sideways slide. maybe i can take my water rudder off if the air one will do the job.

Yogi-Bear

Here is a diagram of the boat its not that good but u can work it out its a really simple strong construction. Use plastic props others maybe weakened by water spray

Yogi-Bear

another angle with radio box and air rudder info the rudders are 2mm plate as opposed to 4mm

rcboatscars

Thanks for the pics. i now have my craft ready to go back to the lake with. still has the 60 os max, got an 11 7 prop for it (12 8 was too much) and turn fin is gone, radio adjusted, rudder was binding slightly, sso i fixed that. ready for the biog one. by the way, the hovercraft i am building is close to completion. probably will be done this weekend, maybe next. should be interesting....JB

rcboatscars

Thanks for the pics. i now have my craft ready to go back to the lake with. still has the 60 os max, got an 11 7 prop for it (12 8 was too much) and turn fin is gone, radio adjusted, rudder was binding slightly, sso i fixed that. ready for the biog one. by the way, the hovercraft i am building is close to completion. probably will be done this weekend, maybe next. should be interesting....JB

nitroman88

My Feedback: (5)

i wish it would get warm enough to test out my .60 dumas big swamp buggy.

rcboatscars

hey yogi
send me your e mail address and i'll send you some pics of my boat that i am making out of the bodyboard. JB

Yogi-Bear

Just a quick thing airboats need to be carefully cg'ed this is dependent on how fast the boat travels however my boat has more weight behind the propeler (sorry have no acurate cg because it was right the first tim eby total fluke) This is ok because the boat only rreaches approx 40km at full throttle if it was to go anyfaster it would flip as at the moment the front of the hull just hangs in the air with only a 1/3 of the boat in the water.
Also carefull attenion needs to be paid to the thrust line yes u can have a boat that is tail heavy and compensate with down thrust but as soon as you cut the throttle what is holding the boat in the water? it will simply take off until you have actually run the boat there is no knowing how to trim it because the speed of the craft is still a mystery.
I havent used them but im sure water trim tabs maybe usefull for a fast boat.
BAsically the boat should be able to achieve full throttle and then be cut to idle with out it wanting to takeoff but should be sitting "nicely" at full throttle so it is achieving its maxium velocity.

The third photo i have posted is of the boat at full throttle it shows the boat half in the water the cg could be slighty furher back or the a bit of up thrust could be added.

Yogi-Bear

Heres a pic as it glides accross a sunset.... bit out of focus unfortunately due to low light conditions.... Oh well

rcboatscars

hey

just had a metal shop down the way make some aluminum pieces for me to copy your design.....heres a few pics of the thing held together by clamps....... whaada ya think?

rcboatscars

another pic

rcboatscars

here's another pic

Yogi-Bear

Nice one enlarge the rudders a bit though other wise it will struggle to turn at lower throttle.mine has an open back it seems you have bent the aluminum up at the rear couldn't see the front mine has the same as your rear for mounting the motor and mount but an open tail as i said i have already had a few ideas on how to upgrade and make a mark 2 mainly th boat wil be lighter....

(did you get my email address)

Yogi-Bear

Hey all i made a 1 minute 21 meg video of my airboat running its shows a high spped pass, low speed and some full throttle donuts only prob is where to post it on the internet anyone know?? i can email to people if they want but would prefer to post it somewhere as the internet company has regulated my upload speed

Yogi-Bear

http://www.geocities.com/will_y66/home.htm my airboat website will be adding links and the movie soon i only have 15 meg of space so im still looking for somewhere to post the movie any help appreciated thanks
Will

rsieminski

rcboatscars,
I built one out of a body board similar to yours, but I fiberglassed the whole thing. How did it go? Where did you put the CG?

Yogi-Bear's has a more hull shape to it. At anything more than 1/3 throttle, it bounces wildly. Is it nose heavy? Is the hull too flat? It does go like wild accross the tall grass, but I can't open it up on the water.