Rcjetflyer2
Hi all,

I wanted to share my latest VTOL creation: a quadrotor biplane.



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This type of vehicle configuration offers unique advantages: a small footprint, vertical flight capabilities, high payload capacity, and long endurance forward flight. Stability in hover is achieved similarly to a conventional quadrotor through RPM of the rotors. In forward flight, control can be maintained through rotor RPM inducing moments on the vehicle alone, though augmenting this with additional control surfaces provides additional redundancy.

I have mine setup in my flight controller to "swap" the rudder and aileron for forward flight, and engage the stabilized elevons. Swapping the controls allows it to fly identically to an airplane in forward flight rather than like a quad pitched over 90 degrees. Personal preference 🙂
The above video is the first flight in which I performed a full transition into airplane mode (and was filming myself, sorry for some of the bad shots!). It flies very much like a wing that is on rails, since it is stabilized in forward flight as well. In the future I would like to compare flight times in hover vs. forward flight, and potentially try to modify it for extremely high forward flight speed. Stay tuned!

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The build is dollar tree foamboard with a kfm-2 airfoil, and 3mm carbon spars to reinforce the wings. The fuselage is 3D printed and houses my custom flight control board, ESCs, and battery. Its a bit of a tight fit, but the aerodynamic housing really helps in forward flight.

I've attached plans (full sheet + a4 paper printable) + .stl files for the motor mounts (standard 16mmx19mm motor mount) and fuselage pieces. The fuselage can either be printed from my .stl files (print two of each and glue together with 3mm carbon spar to reinforce them--to fit on smaller print beds), or built up from foam--the fuselage profile is included in the plans.

pdfplans_a4.pdf
pdfplans_full.pdf
stlfuse_shell_front_half.stl
stlfuse_shell_rear_half.stl
stlmotor_mount.stl

cad1.pngcad2.png

Cheers!

Alfred Gessow Rotorcraft Center, University of Maryland
My Youtube: https://www.youtube.com/channel/UCPe7XrmOPtz4OjL6KGtvJMA
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Rcjetflyer2
Check out this awesome video by a buddy of mine who also specializes in quadrotor biplane platforms:

Alfred Gessow Rotorcraft Center, University of Maryland
My Youtube: https://www.youtube.com/channel/UCPe7XrmOPtz4OjL6KGtvJMA
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mastermalpass086
You both in Maryland? My brother lives there! 😃 

I've contemplated sticking a pair of wings on a quad to make it more efficient for longs flights, but figured racing quads aren't really about efficiency. Making it tip over 90 degrees is something I didn't consider though, but as you have demonstrated it needs a bit of extra programming. Still these bi-plane props look very Star Wars, makes me wonder what other wonderfully weird models you could make around this concept.

Bit unrelated, but this idea doesn't really belong anywhere currently; I have contemplated an idea for a kind of induction fan & Nozzle 'quad' that I could hide inside a spaceship. Someone on youtube made a Harrier that runs on a single EDF so I'm wondering if my idea here is possible:

assualtfrigate.jpg 
Where I'm lost is how to program a flight controller to manage the thrust on each nozzle. I've considered servo-managed shutters inside the pipes to vary the thrust. 
BRB - Building another nosecone.
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SukhoiLover
Here’s a little something to “muddy the waters . . .” The Starfury from Babylon 5.

A5916FF4-7F26-4564-B637-D56854AB02FB.png  2997DD0B-56E5-4DF5-86B3-0FBA7C921CE6.png
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Rcjetflyer2
Oh man, those designs all look cool--got me thinking about the next project iteration already. That ducting system does remind me of a harrier, I've been thinking about the required mechanisms to make that work. Definitely a servo driven outlet regulator on all the exhaust ducts for roll and pitch. Then maybe just one on a tilt for yaw, though two would help counter the torque from the rotor a lot easier
Alfred Gessow Rotorcraft Center, University of Maryland
My Youtube: https://www.youtube.com/channel/UCPe7XrmOPtz4OjL6KGtvJMA
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