Posted by Dror Caspi on October 4, 2010 at 10:00am
Not a DIY but an interesting drone concept... As far as I can see, it can take off, hover and land as a tricopter, and also swing its two forward props 90 degrees to fly as an airplane.
How complicated is the control for the 2-rotor VTOL you describe? And the in-out seems tricky. Seems to me a rear prop is a pragmatic solution to achieve less complexity
Rear prop is not needed at all if only they 1) counter rotate the wing props, 2) when swivelled up align those two props with the CG, 3) and have not only down/up angle control, but in/out as well. They are not taking advantage of propeller inertial effects or the unbalancable thrust torques (which align with the inertial forces when changing in/out angle). There are enough degrees of freedom in this method to control 3 axis attitude and motion. The in/out scissoring for VTOL mode couples to the pitch axis control, for which there are example 2-rotor VTOLs out there.
In terms of efficient flight, it will always be better to have the fewest number of motors on during cruise. If its possible to make the rear motor swing down and have EDF on the wings, it would be best given this train of thought. However, there would be drag and lift losses due to the EDF cutouts in the wings. Having a pusher may also limit the size of the prop you can use which reduces eff. and increases noise. It depends more on the airframe size as to which method is best.
Yeah, I've been thinking of something along those lines myself as it would be some fun stuff to program the conversion from vertical to horizontal flight. Was thinking more of a large central lifting propeller with two thrusters that rotate 90 degrees and perhaps a delta wing...
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