RCExplorer BiCopter prototype spotted at FliteFest!

[LitterBug]

Testing Oblique Active Tilting on the EZBicopter with a 3D printed mod. Initial test flights allowed me to fly with default PIDs where I had to cut PIDs in half before. It’s a simple slip on mod. I do believe that a tail of some sort will be required to help stabilize the pitch axis. Currently, all the mass is at the centerline of the EZbi and it is very susceptible to swiging like a ball on a string.

45 degree rotation of the RCE tilt mechanism

Complete testbed

Cheers!
LitterBug

[Kevin_Erik]

@Litterbug

Shoot menthe specs for that and maybe i can remix it to work like the ITM.

[LitterBug]

It’s a mount that is 45 degrees to the main spar. I tried to make it simple so that it would be easy to swap it in and out without major changes to any wiring/gear. So a 14×14 tube with ID of 10×10, with a 10x14x70 solid beam intersecting. In theory, you could zip tie the Impossible tilt to it as well as the stock RCE tilt. I’ll post up the .stl as well as the OpenSCAD file used to create it to my Thingiverse feed later today.

Cheers!
LitterBug

EDIT: https://www.thingiverse.com/thing:3062508 <– added Oblique source and .stl

• This reply was modified 5 years, 1 month ago by LitterBug.

[Kevin_Erik]

Ahh now i understand… This pics were a little mis leading in that I thought it was like a dihedral angle but rather you’re rotated the entire assembly. Thus when tilted forward the thrust is pushed towards the copter and outward when the copter reverses.

Side Note: you could angle the carbon rods upwards 10-15 degress and have the thrust always vectored away from the copter.

[jihlein]

While true, that’s not the reason for the 45 degree oblique rotation. The reason for the rotation is to use the gyroscopic precession moment created by the rotating motors/propellers to create a much larger pitching moment than rotating the motor around the lateral axis alone. Given that, I would not angle the carbon arms upward, I’d keep the propellers in the same plane. Also note that it is critical that the left motor rotates CW and the right motor rotates CCW when looking at the vehicle from above with it pointed away from you, otherwise the precession moment is the wrong way.

This is not my idea, I found a technical paper detailing the application of oblique tilting to the control of bicopters. This is called single axis Oblique Active tilting, or sOAT. There are some short comings that can be overcome by using dual axis Oblique Active tilting, dOAT, but that’s probably a little too complex for a vehicle this size.

There may also be a need for a fixed horizontal stabilizer to help with the typical desire for the vehicle to pitch up in forward flight, but first I just want to see where the sOAT alone leads this experiment.

But after reading this paper a few times, I think my Trex 450 SE may lose its main and tail rotors and become dOAT controlled over the winter.

BTW – I’ve not posted the paper here because in order to download it, I had to answer a bunch of questions detailing my interest in it (academic, industry, personal, etc) before I could download it. Given that, I didn’t feel it was proper to post it on an open forum. The paper is titled “Lift Fans as Gyroscopes for Controlling Compact VTOL Air Vehicles: Overview and Development Status of Oblique Active Tilting”. The author is Gary R. Gress. If interested, you should be able to find it thru Google.

[LitterBug]

And now there is a build video! 😀

Just waiting for my kit to arrive…. 😀

Cheers!
LitterBug

[LitterBug]

AND SHIPPED! 😀

Hi there. Your recent order on RCExplorer has been completed. Your order details are shown below for your reference:
Your order was shipped via PostNord Logistics

Cheers!
LitterBug

[Kevin_Erik]

Gratz!

[LitterBug]

Kit has arrived! 😀 Transfer of components from EZbi #2 has commenced!

Cheers!
LitterBug

• This reply was modified 5 years, 1 month ago by LitterBug.

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