1988

Item 1988

DESIGN: Electrotor-SloMo - Control - Flight - Auto-Collective by Torque-Pitch - Torque Reactor - Spring

Torque:

The force from the motor at full power and 5" radius is 270 lbs. From DESIGN: Electrotor-SloMo - Rotor - Hub - A - Torque Calculations.

Assuming that this could be doubled due to perturbations or overpowering the motor, or slow weakening of the springs the maximum thrust should be considered as 540 lbs.

If there are 3 die springs in repulsion then the force must be 540 / 3 = 180 lbs each at the position of maximum compression.

If there are 6 die springs in repulsion then the force must be 540 / 6 = 90 lbs each at the position of maximum compression.

If there are 9 die springs in repulsion then the force must be 540 / 9 = 60 lbs each at the position of maximum compression.

If there are 12 spring steel expansion clips in repulsion then the force must be 540 / 12 = 45 lbs each at the position of maximum compression.

How much torque resistance will the elastomeric ring contribute? Probably nothing of significance

The currently preferred method is Idea B.

Idea A:

Drawing for Hub-A:

Also see 1893.html and 1987.html

Possible Locations:

The motor's rotor has less angular change than the pitch are does for a given linear movement.

There are 6 areas on the hub that currently have a lot of available space. They are located on each side of the pitch-arm at the top or the hub. Six 'pins' could be extended up from the Rotor Housing [1978.dwg] into these regions. However only 3 of the area will work with compression. The other 3 can be used as ground adjustable stops for the autorotation pitch.

The pin length MIGHT be used to determine the maximum pitch stop.

Note that the 3 springs work in unison on the pitch of all blades, not on the individual blades. GOOD.

Spring:

The current objective is to have 3 compression (die) springs in each rotor. They will have an OD of approximately 9/16".

They will be supplemented by the torque resistance in the Elastomer rotor bearing

A compression spring calculator can be found at http://www.efunda.com/designstandards/springs/calc_comp_designer.cfm#calc

The torque calculations are located in DESIGN: Electrotor-SloMo - Control - Flight - Auto-Collective by Torque-Pitch - Torque Reactor - Spring

Idea: Consider a torsion spring wrapped around each blade-pitch stub shaft. However, it can only have a few wraps otherwise the amount of torque will not vary sufficiently with the change in pitch.

Pin:

The pin will go inside the die spring and into pockets in the screw and the Housing [1978]. They are intended to assure that the spring will operate properly.

It will be sloppy in the pockets to allow for alignment changes during operation.

The spring etc. must not be subjected to wear.

The overall length of the spring will determine the change in force between its extended and compressed positions.

Parts Required for the Preferred Method:

# Die springs

# Special Bolts (screws)

3 Locking means for bolts

3 pins inside springs

Concern:

If a spring should brake or the springs and elastomeric ring weaken the torque reaction may not be strong enough for the RRPM to override the drag of the higher pitch. This might cause the collective pitch on the rotor with the weaken torque-pitch to climb to its maximum allowable setting, which will be higher than that of the other rotor. If not too different could a lateral weight-shift by the pilot overcome the dissimilar thrust?

Idea B:

Working Notes re Number of Springs:

Motor's rotor diameter at spring prongs = 10.875".

Motor's rotor circumference at spring prongs = 34.1786".

120º of motor's rotor circumference at spring prongs = 11.3929".

Minus width of control bearing structure of 1.75" = 9.6429".

Minus width of 3 tabs of 3/4" in motor's rotor of 1/2" = 7.3929".

Minus width of 4 tabs of 1" in rotorhub of 1/2" " = 3.3929".

Minus width of 4 expanded springs of 3/4" = 0.3929".

Must add 0.3929" into the circumference.

Spring:

Spring steel expansion clip

Just the basic idea, but with a different profile.

Drawing for Hub-B:

12 springs around the circumference of the rotor.

Blocks on the inside of the rotorhub have not been used since there is the need to install the upper bushing or bearing that goes between the rotorhub and the motor's rotor.

No means for adjusting the; force, maximum stop, or the minimum stop are yet considered. The force might be reduced by using a different gauge of spring steel and/or by removing 3 of the springs.

The steel clips might provide a little cooling for the magnet's flux ring.

Notes:

Adjustment of Torque Resistant Force: The springs might be produced in 2 or 3 different strengths (guages?). This gives the ability to replace some, or all, of the springs in lots of 3. This should provide a large range of combinations of force.

Breakage: The breakage of a spring clip will likely occur at the small outmost radius. Can this be overcome by inserting a semi flexable rod inside the radius that will cause the straight sections to take more of the bending?

Breakage: Make sure that the breakage of a spring during flight cannot affect the safety. The pieces might be held by magnetic flux ~ for better or worse.

Initially displayed: November 18, 2010 ~ Last Revised: May 18, 2011

The above utility invention is openly and publicly disclosed on the Internet to negate an entity from patenting it, to the exclusion of all others whom may wish to use it. ~ Reference patent law 35 U.S.C. 102 A person shall be entitled to a patent unless - (a) the invention was known ... by others in this country, ..., before the invention thereof by the applicant for patent.