Oberto cowling construction
Work continues on the 1/10th scale Oberto, with the addition of the top decking. The center section of the deck will be removable and taped down for racing.
I have started to build up the cowling. I am building it over the taped down center section to that the proper curvature of the deck is maintained.
Right now the entire hull with the wood work nearly complete weighs in at 2lb 3 oz. I am hoping that the overall boat when ready to race will come in between 5.5lbs to 6lbs. That would be a more than a pound lighter than the 7-11.
Update: The cowl is nearly done - just some sanding and work on the fillet at the bottom of the cowl to finish. The nose piece is also on so that pretty much completes all of the wood work. There will be some scale detail work to do in order to make the driver cockpit a bit more realistic, but I like the basic shapes. With the wood working finished the boat weighs 2lb 7oz., which is ok I think. The next item on the build list will be to do some fiberglass work on the sponsons and deck joints for a bit more strength.
The scale driver is on order - a 1/10th scale 70's era driver from Hansen racing along with their Merlin exhaust stacks. The plan for decals is to get a set of scale decals from Wesley's Custom Graphics.
For power I hope that the new Proboat and Aquacraft 1800Kv motors get approved for use in 1/10th scale at the PSFE winter meeting. If so then I think that one of those will be a good motor for this boat.
Just as a test I put a motor, rudder, strut, receiver, turn fin, 5000 mah batteries and everything else into the Oberto hull and weighed it.... 5lbs 1oz. Sweet. Obviously paint and some fiberglass are going to increase the final weight but with any luck we should stay under 5 1/2 pounds. That would be outstanding and almost 2 lbs lighter than the 7-11 and easily a pound lighter than the 1990 Oberto.
I also really like how the 82 Oberto has the main hull going up to about 7 inches behind the front tip of the sponsons, and there is a ton of room in the hull for moving the batteries around. With the 7-11 the batteries are 10" behind the sponsons and the 1990 Oberto has the batteries about 12" behind the sponson tips. That forward positioning and range of motion should really help with getting the CG right. Then if you consider that the boat does not have a rear tail - which is just more dead weight at the back of the boat, we have another little boost to getting the CG right.
So a little test: I put the hardware in the boat at the approximate locations where it would install. With the batteries at the nose the balance point was about 1 .5" behind the sponson. Moving the batteries back toward the motor changed the balance point to 2 1/2" behind the sponson. That is a nice adjustment range and would seem to be right at the sweet spot for balance. No extra nose weight required.
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