Hi   Paul


I have been interested in the reduction gearboxes using Auto Trans planetary gears.

I am interested to know if someone has ever found out or knows what torque they will withstand.

as you know i am building my helicopter with a Mazda Rotary Engine which will be Vertical and the Gearbox will be above the engine to the main shaft driving the rotors.

I am wondering if the gearbox would be able to handle the torque required

 I will be able to confirm Torque next week, Joe ( the guy building my engine at Rotormaster Sydney) is building a similar engine and said he would test it and let me know,

I know they use a lot more HP in Drag Cars and I guess that that means more Torque and perhaps I should look at something of that caliber, interested to know any  thoughts?


The specifications for my engine are as follows, Im not sure what torque is required to turn the rotor constantly.

 I believe series 7 engine with single turbo

the engine will be running at 5,500rpm.............therefore 200 HP at 5,500rpm which will be about maximum torque  of 217ftlbs to 263ftlbs


The Rotorway 162F which this is the later design and Scorpin owners in US are now using the rotorhead design  had a 4 cylinder piston engine produced Max 150HP - 160HP with Max torque 185ftlbs to 191ftlbs however don’t know the rpm
Yes just wondering if the Ford gears would handle the torque?


If this is not enough information please let me know and I will chase it up

Hope you or someone else can help me out here

Kind Regards
George Crooks

The Ford gears will not handle rotor torque.
You will need a final drive. You will still need the Ford gears so
get together with Neal in Parkes.

Why is the engine only running at 5,500 RPM?
Rotaries love to rotate at higher RPM's.
6000 RPM gives the lowest load on the rotor bearings.

With a turbo charged engine the minimum rotor bearings
loads are even higher than that.

I can under stand why you want a turbo because high altitude
performance is better. Shoot for 300 HP at sea level with
a 8500 RPM red line. You don't have to use all the power at
sea level.

The best and lightest helicopter designs  are built with a cog belt
final drive reduction at the rotor head. That minimizes the length and hence
the weight of  high torque large diameter and very strong heavy rotor shafts.

 If you know the rotor diameter you can figure
the rotor RPM as the tips cannot go beyond .8 mach.
If the rotor is 80% efficient the thrust HP will be
80% of 200 or 160 HP.

http://en.wikipedia.org/wiki/Horsepower

HP = (RPM X Torque) / 5252

HP X 5252 = RPM X Torque

(HP X 5252) / RPM = Torque

or Torque = (HP X 5252) / RPM

Now you know the torque on the rotor final drive.

Paul Lamar