# Tandem-rotor Gyroplane

#### Resasi

##### Gold Supporter
Disconnect the drive to the rotors and see if a Chinook will fly?

##### André MARTIN
Disconnect the drive to the rotors and see if a Chinook will fly?

The Chinook does autorotate!!!!

#### DennisFetters

##### Gold Supporter
The Chinook does autorotate!!!!

What Resasi means, or should mean, is it requires a connected drive system to each rotor system to maintain the same RPM, even in autorotation.

In a gyroplane, it would be possible, in fact probable that one rotor system would gain RPM or loose RPM if not connected, causing an irreversible decay due to the continued lift of the other rotor system, causing the tail or nose to sink and tumble.

If you did make a gyro with connected rotor systems, the drag of the system would make such a aircraft very inefficient when relying on only autorotation to power the rotor system.

##### André MARTIN
What Resasi means, or should mean, is it requires a connected drive system to each rotor system to maintain the same RPM, even in autorotation. Yes, otherwise you have the destrruction of the rotors
In a gyroplane, it would be possible, in fact probable that one rotor system would gain RPM or loose RPM if not connected, causing an irreversible decay due to the continued lift of the other rotor system, causing the tail or nose to sink and tumble. I have seen this kind of RC aircraft flying with separeted, non intermeshing rotors, i don't find the video but this one...

If you did make a gyro with connected rotor systems, the drag of the system would make such a aircraft very inefficient when relying on only autorotation to power the rotor system. Calculations show that a rotor, with a half the weight to lift and, a half the weight of a reference rotor (t.t.s. all dimensions divided by the cubic root of two=1.26), has a better L/D than the reference rotor...The same for the props...

I must go ahead with a quadrirotor!!!

#### DennisFetters

##### Gold Supporter
It's true, you can do a lot of things with toys.

I'm talking about real aircraft that carry people, which makes it a different world.

#### Rotor Rooter

##### Dave Jackson
Info;

Question;

1. What is the reason for the second rotor when rotating the rotor(s) does not create a counter-torque in the craft?

##### André MARTIN
Answer is in the patent...

#### DennisFetters

##### Gold Supporter

I'm not going to bicker with you.

Believe what you want.

We were talking about tandem gyro's with unconnected rotor systems. I did not say models were not used to develop aircraft. I said you are not in the real world if you believe you can make a full scale tandem gyro with unconnected rotor systems fly with people on board.

Make one fly with people on board and prove me wrong.

#### Rotor Rooter

##### Dave Jackson
Andre;

The negative;
I believe many have said that the early tandem helicopters, which were not equipped with Stability Augmentation Systems, were not the pinnacle of stability or controllability. Having read the patent, I suspect that his tandem gyrocopter will be no better and perhaps worse.

The positive:
By God or by Darwin ~ Your choice

Dave

##### André MARTIN
I'm not going to bicker with you.

Believe what you want. I believe in nothing without proof!!! I know you are a great believer!

We were talking about tandem gyro's with unconnected rotor systems. I did not say models were not used to develop aircraft. I said you are not in the real world if you believe you can make a full scale tandem gyro with unconnected rotor systems fly with people on board. You believe it's not possible!...
Make one fly with people on board and prove me wrong.

The purposes of this thread is not to build a tandem-rotor gyro (even with an interconnection) It's only to stimulate our fingers!!!...:typing:

##### André MARTIN
Andre;

The negative;
I believe many have said that the early tandem helicopters, which were not equipped with Stability Augmentation Systems, were not the pinnacle of stability or controllability. Having read the patent, I suspect that his tandem gyrocopter will be no better and perhaps worse.

The positive:
By God or by Darwin ~ Your choice

Dave

Anyway, gyrocopters are not the pinnacle of efficiency!!!

#### joe nelson

##### Senior Member
gentlemen,

I have researched information about the tandem rotor system as a solution for my large gyro. What I've read was a tandem is only about 35% more efficient than a comparable single rotor system. The shortcoming is that the airframe has to be more than 50% heavier to support the additional rotor and control system weight. The drag on this configuration could be as much as three times greater requiring larger engines/fuel consumption.

If the control issues could be overcoming the tandem would still be grossly inefficient... more so than the typical gyro.

##### André MARTIN
gentlemen,

..... the tandem would still be grossly inefficient... more so than the typical gyro.

You'd better look for a four blades rotors for your heavy gyro:
a four blades rotor has a better L/D (15-20%) than a two blades rotor of the same weight... (t.t.s. all dimensions with a ratio of "cubic root of 2"=1.26). Use two contrarotative props...A stab with an elevator...etc...But anyway, it's up to you!!!

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#### joe nelson

##### Senior Member
Andre,

One idea that you have on your aircraft that I like is the "ring tail". In the Piasecki study, the fan can and did compensate for torque. For partial power gyros, a larger amount of power (read higher rrpm) can be diverted to the rotor for jump take offs and low speed situations.

##### André MARTIN
Andre,

One idea that you have on your aircraft that I like is the "ring tail". In the Piasecki study, the fan can and did compensate for torque. For partial power gyros, a larger amount of power (read higher rrpm) can be diverted to the rotor for jump take offs and low speed situations.

What can simplify rotorcrafts is the vectorizing tail: in the case of the Touringcopter, you have control on yaw and pitch...
And with a balloon, it's amazing!!!...

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#### joe nelson

##### Senior Member
Andre,

I think the most effecient configuration would be with a constant speed prop/fan. This would allow maximum hp to be directed to the rotor for prerotation. The proverbal fly in the ointment would be both rotor and prop would need to be at max pitch nearly simultaneously for a jump t.o. However I think it's very doable.

Maybe, I should look into a compound aircraft like the the rotordyne or the Piasecki X-49.... it would solve some nagging problems.

##### André MARTIN
Joe, what are your nagging problems?

#### joe nelson

##### Senior Member
Andre,

The wings would give me the extra storage space for fuel and a place to get the fuel away from the cabin. As you may have guessed this gyro will need a rather large engine (IO-540) so the fuel consumption/ range has been an issue. I also wanted to put all fuel in a fuel cell making the floor of the cabin larger than expected. The wing may also unload the rotor enough to make small gains in range/ endurance. I had considered a system like the ESSS on a Sikorsky Blackhawk but that was something I would address in the future but drag was a concern! Originally, I wanted to put a small amount of fuel under the floor and, if need be, carry extra tankage externally.

My biggest problem is keeping the empty weight about 1500 pounds. That has always been a problem in aviation since Orville and Wilbur! LOL

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