DESIGN: Electrotor-SloMo - Rotorhead - Hub-B - Overview & Layout

• The blades are located above the motor.
• 3-blade rotors.
• Hubs are at 15" centers with the means of synchronization to be determined. Perhaps 9 lobe gearing at the plan of the blades.
• Small, medium or large diameter mast. Going with Medium Diameter Mast.
• Pitch change or Twist change. Currently going with pitch change with hub stub spar going into blade root, and held with single tapered pin. See: 1993.html & 1994.html

This is the current one. It is on 1900.dc not on 1526 ++++.dc

The blade will be 1955.html #6 with 1961.html or 2046.html root block.

• Root of spar must be a slip fit into the 2 bearings and the splined pitch arm. This represents both movement and wear.
• The thread on the rood end of the blade's spar will wear.
• Loacate a tapered pin otboard of the bearings.

• Wiring:
• A motor with 6-phases and duplicity will require 16 busses.
• Approximately 1/2" of the thread must be cut off the M3 cap screws.
• See 1983.dwg
• Breaststroke rotation (inside forward);
• Advantages:
• Torque-pitch (of principal assembly) coupling, and
• Place the closing of the teeth at the rear where there is much less chance of experiencing foreign objects.
• During forward flight with outside forward the advancing blades are lower than the retreating blades. These lower blades will produce greater lift and this will reduce the vertical distance between the upper and lower blades. This is of particular interest to any though of ussing opposed longitudinal cyclic on the intermeshing for yaw control.
• Disadvantages:
• If the blades were to have a greater pitch on the retreating side, a some point in the future, it would be advantageous to have the spanwise shift of the lift outward toward the tip which is operating beyond the disk of the other rotor.
• Safety re Synchronization Spur Gears;
• Consider covering the two gears with a lightweight, stationary figure-8 guard. The gap between this guard and the aero-rotors would be smaller then the gap between the 'sloppy' teeth.
• This guard might also incorporate a 'funnel' aft of the rotors that draws air through the coils of the motor during forward flight.

Pitch Shaft: So far just a rough overview.

• Thread:
• Note that the thread and bolt on the shaft with taper pin will be infrequently removed and reinstalled, whereas the thread and bolt on the shaft that is inbeded in the blade is remove and reinstalled at every use of the helicopter. Consider long bold that has softer material then the bolt portion.
• From Table: The axial force on the thread [from DESIGN: ~ Electrotor-SloMo - Rotorhead - Hub - A - Blade Generated Forces - Preliminary:] will be between 1,053 lbs = 4,684 N and 1,474 lbs = 6,557 N.
• a2. Full Power Flight: Centrifugal load factor = 4.0. Safety factor for centrifugal loads = 2.25.
• Force on thread could be up to 1,474 lbs = 6,557 N., times 9 = 13,266 lbs = 59,039 N.
• Tapered Pin:
• See: DESIGN: Electrotor-SloMo ~ Rotorhead - Assembly - Taper Pin
• Thread Strength:
• A 5/16" bolt has a cross-sectional area of 0.0767 in². So a 5/16" AN bolt has a rated tensile strength of (125,000 x 0.0767) = 9,587 lb. And a 5/16"; Grade 8 bolt has a rated tensile strength of (150,000 x 0.0767) = 11,505 lb.
• See 'Bolt' on; DESIGN: Electrotor-SloMo - Rotorhead - Hub - A - Grip-S
• Other Related Information:
• OTHER: Mechanics - General - Hardware
• DESIGN: Electrotor-MicroLite ~ Power Train - Miscellaneous
• Consider 7/16" or AN7: or larger, particularly for the taper pin version.
• Spline:
• A larger diameter (or strong retaining ring) should be located on the shaft, outboard of the inner bearing. This is to take the torque when tightening on the inner race of the inner bearing. This larger diameter will likely have to have a slip-fi spline so that the pitch arm can be slide past it.

• This disk (ring) is attached to the bottom of the hub, item 2036. It's function is to;

• The rotational forces will be fairly light on this because the 'springs' are mostly expanded at minimum pitch and the motor is offsetting the resistor at maximum pitch. This assumes that the torque resistor is operating between the motor-rotor and the rotorhub, and the pitch links are not involved in this force.
• The intention may be to never have the maximum pitch stop ever contacted, except in the case of malfunction.

• Consider having the upper cooling holes on the side of the rotor hubs. If the blades are turning outside forward then the air can come up from below and be drawn out the sides by a 'funnel' at the rear that provide a reduced pressure behind the hubs during forward flight. These side openings may prevent rain and foreign objects from getting into the motor's coils and air-gap.
• Consider the possibility of using the synchronization gears to act as a gear pump to move cooling air through the coils. They might not move sufficient air, but they due operate during hover.
• Maybe the above 2 ideas can be combined.
• A smaller disk radius offers some advantages, (as are mentioned somewhere else, which I cannot find) but another one is that the fan portion of the rotor will be turning slightly faster and therefore passing more air past the coils.
• See; DESIGN ~ Electrotor-SloMo ~ Motor - Radial Flux - Stator - Cooling

• Cannot get large enough aluminum billet, at least not from Speedy metals. Consider casting in aluminum or produce in composite from the start.
• Composite Construction ~ Preliminary Notes:
• Create an oval mandrel that is the size and shape of the air holes.
• Wind tow or unidirectional tape around it with the treads normal to the axis of the oval.
• After curing, the oval tube can be cut at the required lengths and angles so as to become the walls of the holes.
• The area between these tubes can be filled with foam, chopped carbon, micro balloons etc. so as to become strong ribs.
• There are more notes on paper in binder.

• Stator:
• The lamination count will be increased by 50%, etc.
• Rotor:
• The magnets will be changed from 1.5" long to 2" long on the existing rotor, etc
• Hubs:
• Another snap ring groove will be cut in the lower end of the mast.
• A 1/2" wide ring will be inserted onto the bottom of the hub.
• A 1/2: wide stepped ring will be inserted between the upper and the lower hubs.
• Exc.
• Mast:
• New one must be made 1/2" longer and 1 or 2 more cooling fins.

• Maximum Collective Pitch Stop:
• Minimum Collective Pitch Stop:
• Collective Damper:
• For information related to an elastomeric damper see; DESIGN: Electrotor-SloMo - Rotorhead - Hub - A - Elastomeric Rotor-to-Rotor
• Torque-Pitch Reactor Adjustment:
• Blade Pitch Balancing (equality):

Introduction Page | SynchroLite Home Page | Electrotor Home Page | UniCopter Home Page | Nemesis Home Page | AeroVantage Home Page