Tandem-rotor Gyroplane

I understand that mate, Just wondering how it all worked out?

Cheers
At this time, I am stuck on finding a suitable gearbox for my model. Two types were used with one from a Honda motorcycle and one purchased from a local distributer. I haven't had much success in determining the "gear box drag" and it's effect on the autorotation of the blades. The blades won't spin-up in front of my floor fans when rotors are coupled to each other's gearbox. They spin-up OK when not coupled.

The problem that arises is that when the uncoupled rotors spin-up the airframe rolls left and falls over.

A copy of a tandem rotor gyro patent was found and it shows the front rotor on a higher pylon than the rear rotor. These changes were made on the model resulting in better spin-up but it looks like it is flying backwards. I assume that this because of the difference in airflow up though the blades.

All of this, the original problem remains. How to overcome the gearbox drag?
 
I have decided to change the gear boxes for drive belts. I am hoping to reduce the "drag" generated through gear boxes in the coupling of the rotors.

The drive belts were use on several homebuilt helicopters. The system has been proven for use on tail rotors, hopefully, it'll work on coupling rotor on my models.
 
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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
bull shit. Tandems like to fly sideways , 200 kts been there - Fort Rucker test unit. Fritzy field - SAS not needed. only node weights.
 
I have decided to change the gear boxes for drive belts. I am hoping to reduce the "drag" generated through gear boxes in the coupling of the rotors.

The drive belts were use on several homebuilt helicopters. The system has been proven for use on tail rotors, hopefully, it'll work on coupling rotor on my models.
cog belts with a twist ? will work
 
Joe, your research regarding this setup looks promising, and after doing a quick google it looks like someone has put a patent on it?

Cheers
Matt
There is one paten that I am aware of. I used the same configuration on one of my models with mixed results. I am not saying that it wouldn't work as in the paten because my model building is very sloppy at times. I did add several changes like blade overlap and different heights of the front rotor mast to get smooth airflow into the aft rotor. My only problems at this point is the coupling between the rotors and engines of appropriate horse power.
 
For the life of me, I cannot find the original RC Aviation website where I found the following photos of a tandem gyroplane based on the Piasecki HUP-2. I don't remember and stats on how well it flew. One can see the blades are not interconnected.

Wayne

1620270083541.png1620270128640.png
1620270179085.png
 
Wayne, In my experiments, I found that when uncoupled the rear rotor moves to the left. The reason is unclear to me because I was unable to couple my models.

As I look at this RC tandem the construction is much better than any of mine. This rotor configuration wouldn't work on my models with the high front rotor mast and a higher rear rotor. When the rear rotor mast was shortened the model acted much better. I set them raked back to around 9 degrees and a overlap of 30 percent. This allowed the air to flow smoother into the rear rotor undisturbed by wash from the front rotor. The overlap made the airframe shorter to reduce weight.

Has anyone seen this bird fly?
 
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