You are using an older browser version. Please use a supported version for the best MSN experience.

Dobbertin HydroCar - Water Test 4 - Amphibious Vehicle

 (Continued from Water Test Three)  These quick modifications resulted in less cavitation and a bit more speed, but we still couldn't get it up on plane.  It almost seemed that the HydroCar had added some weight on the last two launches -- and indeed it had.  At this point, we thought the main problem was still the prop, not realizing the rear wheel wells were not self-bailing adequately.  Modifications after Water Test Four:  Studying the videos and calculating the latest modifications, it was obvious that we had gone too far with the weight transfer.  To understand the problem that we had created, the following is a little design information:  The HydroCar's wheel wells are covered on the bottom with sliding panels similar to the landing gear doors on an aircraft -- but they are not watertight.  Water enters the wells through the axle openings as well as around the bottom panels.  To drain the water out of the wheel wells, each well is designed with a trough in the rear to self-bail any water that might accumulate, as soon as the craft begins to move forward.  The front wheel wells had adequate-sized troughs, but the rear wheel wells did not.  On launches three and four, with a lot of added buoyancy in the nose, the front wheel wells had self-bailed -- but not the rear ones -- so they had actually filled with water.  This resulted in the craft dragging over six hundred pounds of water along with it (inside the rear wheel wells.)  Add to this the removal of three hundred pounds of floatation foam from the side sponsons, (which was now filled with water) and two hundred pounds of sandbags -- and it was almost like we were dragging an eleven hundred pound anchor behind us!  So...  The troughs in the rear wheel wells have been opened up to accommodate the additional water flow, thus enabling the rear wells to self-bail as they were originally designed to.  A keel-cooler was added under the craft to aid in engine cooling while in WATER MODE.  The electric / hydraulic marine power steering system was changed over to an engine driven pump to reduce the current draw on the electrical system. The HydroCar is now ready to go -- but the weather in upstate New York is prohibiting any additional Water Tests until spring. I've recently had a lot of input from several boating experts and most of them feel we've got it just about everything 'dialed-in' except for the prop. We still need to find a prop with just the right combination of diameter and pitch, combined with the proper number of blades, so the HydroCar can optimize its performance. Once it's up on plane, it's going to be one Hell of a ride!
image beaconimage beaconimage beacon