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
Does anyone know how you control the pitch of the blades for the first
helicopter in the pictures? I see no pitch horn.
Does anyone have a picture of the very early Rotorway rotorheads on
which there was a cable that goes through the rotor head for collective
pitch control? I was told by Rotorway guys that it does not work well,
so the later models changed the design. However, I am looking for a
simple rotor head design for a gyro copter, and that cable design might
just work well. For the helicopter it does not work perhaps because of
the gyro precession pressure. However, on a gyro plane you do not
change the collective pitch during flight. You only change it on
takeoff. Thus I think the cable design would work.
Gordon
More power up, less power down. We don't need no stinking pitch change :)
The rotor head is mounted on a gimbal. It is a weight shift helicopter.
Paul Lamar
Read this for more information Gordon.
http://www.rotaryeng.net/VTOL.html
Paul Lamar
Paul,
Helicopters are not practical without collective pitch. That is how you
control autorotation and and maintain rotor speed with power loss. I have a
concept for putting the rotary in a Rotorway Exec, but I'm on another
project right now. The engine will mount horizontally and I think I will
remove a bunch of weight from the aircraft.
Steve Brazil
Can you set the pitch for auto rotation and still fly?
Auto gyro's don't have pitch change mechanisms.
I notice the Air Scooter has floats. You can always
dive out just before it hits the water :)
The video shows it flying in ground effect but not very stable.
http://hackedgadgets.com/2006/11/24/airscooter-ii-ultralight-helicopter/
Maybe they are out of biz.
As of January 31, 2007, the company reported an accumulated
stockholders' deficit of approximately $11.8 million. Stock value has
declined recently to only $0.07 after trading over $1.00 early in 2007.
http://www.rotaryforum.com/forum/showthread.php?t=23780
Assume for the moment it has pitch change ?
How well would a weight shift helicopter work?
AKA gimbaled rotor head.
Is it practical to use electric servos to change the pitch?
Paul Lamar
Paul,
Think of a column of air going through the rotor disc. When the aircraft is
flying under power as a helicopter, the flow is going down. When you lose
power, the immediate reaction of the pilot is to shove the collective all
the way down. If he doesn't rotor speed will decay, then you crash. When
you shove the collective down with no power, that column of air is now going
UP through the rotor disc and the helicopter is now an autogiro-glider.
When you flare to land, you will pull up on the collective and turn the
inertia of the rotor into lift to cushion the landing. Bell helicopters
have a reputation for being very good at this because of their heavy rotor
blades. Many helicopters have weights in the tips of the blades to increase
the inertia of their rotors.
Steve Brazil
Thanks Steve. Excellent explanation. You would not have
a chart of air velocity through the disk as a function of time
starting at the instant of loss of engine torque would you.
Are we talking milliseconds or seconds here? In other words
how long does it take for the air to reverse direction?
I am sure it varies with the design.
What does the pilot do with the cyclic and when?
Does the helicopter yaw? I would think not because the
tail rotor loses torque at the same time as the main rotor.
Paul Lamar
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