how to build it ..
how to built this sponsons.. i used some styrofoam and glued them together so i have a a brick of 15 * 10* 40 cm i made two of them ..because we have 2 sponsors..
than i start sanding .....this takes some time.. a couple of nights..
finally i have the shape i wanted..
the shape is flat on the inner side of the sponsors, the rise of the sponsons to the front are angled in a 5 degrees angle.. the ride pad .. the "bottom"of the sponsons are in a 8 degrees angle to the outside , this way the sponson cuts like a dull knife in the water.. and is not gliding on the water..
take a look at the pic .. may be this helps...
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engine placement and drive system
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Engine and Stuffing tube mounting
the engine must be placed ,just behind the last sponson.. this means the engine will be mounted in the engine mounts with a little space between the bottom and the sides of the frame , the frame has a typical 5 inch space between them so a Zenoah will fit right in .. the drive collet from the engine must be a bit low so the engine must be placed with a 10 degee angle downwards..
the flex cable will be guided in a pipe which will be 17 inch long and exit the bottom and then ends close at the drive system witch is mounted on the transom ..here a strutt will hold the tube and prop in balance ...i glued this tube with epoxy and some fiberglas clothes..this way it will be strong and the tube has no change of moving ore vibrate...with is not good for the frame,,
EDIT I made a different engine mount as i use a aircooled engine, also modded the stuffing tube with a bigger tube and a piece of teflon at the end near the strut.
This should keep the grease in and the water out.
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Radiobox
the radio box must be inside the frame and as small as possible. i placed the radiobox somewhere in the middle of the frame . in this radio box there are the servo,s for steering and throttle mounted, i placed a 3th servo which i use to turn of the engine if anything might happen ..
the receiver must be placed here as well .also the battery pack and a fail safe is in the radio box .. this fail safe will turn off the engine if the battery deliver to less power or if the rigger gets out of range ..
this radio box must be waterproof.. make sure that there is no water coming in this box..
a hard thing to do because there are a lot of tubes and cables going in and out to steer and drive this monster..
make sure u put a smallsack of silicium in there as well and 2 tampons,,,, yeah thats right tampons .. if by any accident water will enter the radio box ,, you might have a chance that the tampons will absorb the water and keep your servo,s free from water ..
the engine is watercooled, this means there must be water transported trough the frame, this is what i did ..
i used a silicone tube with go from the transom to the engine compartiment , in the rudder there is a water pick up .. and this will give the engine water to cool the cilinder head..
but ... since the engine compartiment is open and close to the waterline .. there is a big change that there will be some water in side this engine compartiment .. if there is to much water the frame will be to heavy to move.. and even worse the engine could die because of all the water ..
we need this water transported outside tis compartiment again .. what i did is this ..
i used a plastic tube which starts in the engine compartiment, and ends outside the transom ..
what happens is this,, because of the speed of the frame the tubes will be draging to the water , this will result in a vacuum in the tube .. this vacuum will suck all water out of the compartiment where this tube ends ..
i have 2 of this tubes .. one for the engine compartiment and one for the last compartiment ..
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