Here is an idea that may be helpful for bicopters/bicopter type VTOLs. Using a 4 bar mechanism for pitch control

By using a 4 bar mechanism to tilt the motors, it is possible to place the "apparent pivot point" called the "instant center" well above the copter for more effective pitch control.

Interesting thoughts...sorry, but I donīt quite follow

Can you make a sketch that illustrates the applying forces and moments?

Cheers, Michael

interesting idea, cant wait to hear how it works in practise.

Originally Posted by VTOLicious

Interesting thoughts...sorry, but I donīt quite follow

Can you make a sketch that illustrates the applying forces and moments?

Cheers, Michael

The sketches below might help clear it up a little.

In interesting note is that the motor translates relative to the cg which equates to weight shift. If the side links of the 4 bar mechanism were parallel to each other, there would be no tilting of the the thrust but there would still be the weight shift component.

As drawn the mechanism gives the tilt and weight shift effects together.

As drawn the mechanism gives the tilt and weight shift effects together.

Well, your IC is the geometrical intersecion of the 2 side links. But what makes you think the whole aircraft pivots around the point what you call the "instant center"?

I donīt see any benefit...by now

Regarding the weight shift: If you donīt balance the motor-nacelle youīll always have some weight shift when its pivoting relativ to the fuselage.

I understand the leadfeather idea, I've tried a lot of mechanism on my tricopters yaws.
The main point for our bi/tri tilt mechanism is to reduce the distance between the tilt center and the prop/motor lift center.

But the four bar mechanism could be usefull to reduce (or to "fine tune") the distance between lift axis and CG/AP of the VTOL.


(I appologize for my poor "mechanical" english)