I have done some thinking about even making an intake shield of alum 2x thick flashing / between me and the duct fans potentially turning them into shrapnel would go through you so fast you would not feel it. these guys turn 34K rpm, I am concerned about blades shattering if something hard gets sucked in. My biggest worry / maybe over thinking, but safety first always. Also did you build or test thrust tubes ? I found some interesting studies on youtube if you want some links. I was concerned about how close they can be to each other before robbing air flow, testing total thrust as I move them closer and further from each other.once this was determined I was going with 4 EDF in a box pattern hopefully at about 48" sq. Mad Thrust 12 blade alum alloy EDF jigged up in a custom bench as we blog this. I would still favor a prone powered harness, instead.įantastic, we are on the same page. This entire power proposition needs some serious work, to be developed into a safe flyin' unit someday. Relays and short heavy wires make good sense, for this application. Even using heavy-gauge wire, you get a lot of power loss through long wires. These switches and wires do not need to be heavy-duty they can be fairly small if they control relays to apply power to the motor. That switch could possibly be used to reverse the engine thrust when the straps go slack, as you have proposed, but in all cases I would want a dead-mans' switch under the pilot's hand as well, which would chop all power to the engine if released. Now it may be possible to rig a weight-sensing switch along the length of the hang-strap, which would open instantly when the strap is not pulled fully tight by the pilot's weight. If these items are mechanical rather than electronic, there would be on-going maintenance costs as well. The cost and complexity of gyroscopes and accelerometers would stop many pilots from installing that equipment. His glider had fixed tips and luff lines, and it was probably more pitch-positive than many modern gliders today. That was too close! He then removed that killer power unit from his glider forever. I watched one (M.C., local HG instructor) pilot pulling sagebrush twigs out of his control bar corners, after a surprise dive during a flat-field take-off. Just the minor mechanical bumps (that you can get over almost any flat field) were enough to cause an instant vertical dive at very low altitude. I am not talking about extreme turbulence here, either. NO HG pilot could do anything sufficient to prevent this dangerous reality. I have seen the keel-mounted power units in flight, and with even minor turbulence, as soon as the pilot goes weightless for an instant, the glider is pitching over violently. I think "exacerbate" is not exactly the right word there. Storing the batteries on the glider rather than on your harness might give you a bailout option in case of battery fire – deploy chute, cut off burning glider.Raquo, However, with current technology it should be possible to equip the glider with redundant accelerometers / gyroscopes that would detect such events as they develop and immediately stop the propeller (or even make it spin backwards momentarily). We stopped doing that because in thermal air such a setup could exacerbate pitch-overs into tumbles. Raquo wrote:One other thing I've been thinking about is how we don't have props mounted on the gliders anymore.
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