Gyro/Heli V - Power Train

Overview:

The 2 current choices allow for a fixed tube to be located in the center of the gearbox. This gives rigidity to the box and frame plus allows controls etc. to pass between cockpit and engine or tail.

Look further into Rick's idea of 2 seats and drive shaft passing between up to propeller at very front of craft.

Gearing Layouts:

Choice A ~ 2 spur gears plus 5 planetary gears plus 3 bevel gears

Choice B ~ 2 spur gears plus 5 planetary gears plus 4 bevel gears

The engine drives the planetary sun gear via a spur gear set. This primary set of spur gears is required so that a rigid tube can pass through the center of the drive train and propeller. This primary gear arraignment also allows for two, side by side, engines. The planet gear holder drives the pinion and ring (secondary reduction), which, in turn, drives the rotors via bevel gears. The propeller blades are mounted on the outside circumference of the ring gear.

Possible Alternative Gearing Arraignments:

HYPOID GEARS; A type of differential final drive using a spiral bevel gear on the drive shaft, allowing it to be located below the center of the ring gear on the axle. This makes possible a lower floor in the car. Ratio around 4:1

What is the power loss with a hypoid gear. I hope it's not anywhere near a worm and wheel.

The upper hypoid gear interferes with the right-hand mast

The friction in the Worm & Wheel option might put slightly more power into the propeller??

 

Reduction:

All reduction takes place between the engine and the assemblage of rotors/propeller. The "reduction' between the rotors and the propeller is just a balancing of power, similar to a differential in a car.

 

►Power Splitting between Rotors and Propeller:

General Gyrocopter Data from Homebuilt Rotorcraft:

If ship's gross weight is 650 lb then there must be 325 pounds of static thrust.

An efficient prop will develop around 5 pounds of thrust per horsepower.

It will take at least 65 HP to develop 325 pounds of thrust.

Torque Calculations based on 50% of power to Rotors and 50% of power to Prop:

Rotor [Torque x RPM] = Prop [Torque x RPM]

Engine is 65 HP

Operating Rotor RPM is 600

Assume; operating Prop RPM is 2400

Horsepower [HP] * 5250 = Torque [Q] x RPM [RPM]

therefor Torque [Q] = (Horsepower [HP] * 5250) / RPM [RPM]

Rotor [Torque] [QR] = (Horsepower [HPR] * 5250) / RPM [RPMR] = (32.5 * 5250) / 600 = 284.4 lb-ft

Prop [Torque] [QP] = (Horsepower [HPP] * 5250) / RPM [RPMP] = (32.5 * 5250) / 2400 = 71.1 lb-ft

Primary (spur) Gearing:

Diametral Pitch: 10

Ratio:

 

 

Driver:

 

Driven:

 

Nbr. of Teeth:

 

 

 

 

Pitch Diameter:

 

 

 

 

Speed: (rpm)

 

 

 

Secondary (planetary) Gearing:

Diametral Pitch: 10

 

 

Sun:

 

Planet:

 

Ring:

 

Nbr. of Teeth:

30

 

15

 

60

 

Pitch Diameter:

3.75

 

1.875

 

7.5

 

 

 

 

 

 

 

 

Ratios:

 

Sun to Ring

2.0

 

 

 

 

Sun to Planet Carrier:

3.0

Planet Carrier to Ring:

1.5

 

 

 

 

 

 

 

 

 

Speed: (rpm)

6400

 

11000

 

2300

 

 

 

Planet Carrier:

-600

 

 

Tertiary (bevel) Gearing:

Diametral Pitch: 8

Ratio: 4:1

 

 

Pinion:

Ring:

 

 

Nbr. of Teeth:

 

 

 

 

Pitch Diameter:

 

 

 

 

Speed: (rpm)

 

 

 

 Overrunning Clutch:

A overrunning clutch will be required between the planet ring and the pinion gear to allow the rotors to continue turning in the event of a disabled drive. The rotor governor will automatically lower the collective pitch of the rotors to the autorotative setting when the RRPM starts dropping below 100% operational RRPM.

Perhaps the Overrunning clutch should be located between the engine and transmission so that the propeller is still operational to direct air at the tail on flare.

There may be no need for an overrunning clutch, just let the propeller turn in the correct direction at 1/4 of the rotor rpm.

Miscellaneous:

Start-up clutch not required because the prop can accept the rotation when starting the engine.

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Last Revised: February 2, 2001