After a lot of crashes I had 5 successful flights with my autogyro today. And that is after having modified it with a higher pylon to improve the roll stability. I also had to decrease the angle of attack of the blades to make the rotor spin up quicker. And it worked.

However there is still a problem. It has good stability when rolled to the left. This means that I can roll it to initiate a left turn and it will keep the bank until I roll it back. But as soon as I roll it to the right it will bank heavily and spiral down. The only way to save it is to quickly straighten it up by giving left roll. So at present time right turns must be avoided.

I wonder what could be wrong. Could it be that the fin area is too small? Or do all autogyros behave like this?
The rotor has clockwise rotation.

/PO

Are you using delta angled hinges? If not they could worth trying. In my experience model autogyros have no particular tendency to tip more to one side than the other. My planes are all built `square` - no built-in tilt, offset pylon, or rudder deviation etc.
Colin

I had the possibility to make some further tests to day and managed to make some right hand turns but they had to be very wide otherwise the gyro tipped over. Quite different from the left hand turns which are very smooth and can be made very tight. To the left it turns almost like an airplane. To the right it spirals down.

The autogiro has some kind of a delta hub. It is molded in plastic and produced by the company PeAs Rotorblad. They also produce the kit I built the gyro from. The blades can flap up and down totally about 11 degrees. They flap around an axis that is perpendicular to the length axis of the blade. I have seen hubs that have this axis angled forward (difficult to describe). Maybe this would be an improvement. On the other hand it is curious that the stability can be so completely different for left and right turns. Possibly it is an indication that the stability is marginal.

I attach some pictures.

/PO

By looking at your bottom picture it appears your blades are mounted upside down. This may be causing the right turn problem. Most gyros rotors spin counter clock-wise.

John

No the blades are mounted the right way as this rotor is designed for clock-wise rotation. I have also seen that most autogyros seem to have anticlockwise rotors but it should not influence the stability. Or does it?
/PO

On my Kellet,blades rotate counterclockwise.Left turns are very nice but right turns are done very carefully since the nose drops in a right turn and climbs in a left turn. This is as should be expected since the blades are acting like a gyro. Read the theory of gyroscopes and you will find out why this happens. You are have the opposite effect so I can't imagine what your problem is. You say your blades are rotating clockwise does this mean that you are standing in back of the machine and the blades are turning to the right? I have flown my Kellet with the blades turning both directions and the same effect is noted. Right turns are nose down for counterclockwise and left turns are nose down for clockwise.

Go to http://www.gyroscopes.org/behaviour.asp for a explanation of gyroscope precession

Ok,

Now I have a question for both of you guys. How did you balance your blades?

I will explain why I ask after you answer.

When I said clockwise I meant as viewed from the top of the rotor. Or if I stand behind the machine the blades nearest to me will move from right to left. When I stand behind the machine the retreating blade will be to the right of the fuselage.
I thought this was the normal definition but after your description of the Kellet characteristics I must have misunderstood it.
Thanks for the link.
/PO

I weigh the blades I put any necessary weight in the middle around the balance point . When I made the blades I selected stock that was very close in weight and therefore I did not require much balancing.My balancing is from tip to hub. The construction is per instructions in Kellet kit. I have a piece of alum stock that is 2 1/2 inches wide 36 inches long and 3/4 inches thick I build the blades on this and use rubber bands to hold the material while the epoxy cures.My blades are FLAT and TRUE.Today I made flight number 104 A gust of wind came up just as I started and I had a true vertical takeoff WOW It climbed up no more than 10 ft in front of me

Did you use any tip weight? On the end of your blades?

The instructions in the Kellet kit said to put weight in the tip to balance but I couldn't understand how that would work since it would get the weight correct but then the tip to hub balance point would be off. Like I said I selected my stock very carefully and the small amount of weight needed I put in the center No tip weights. I don't have a very accurate scale to weigh it's a postal scale. But my feelings now are real close is good enough.

After having flown my gyro several times today I almost begin to like it. Initially a beast it is now more an advanced trainer.
Left and right turns are now easily done. The flip over to the right I had earlier has been solved by setting up the radio for less sensitivity to the right than to the left. I have also mixed in some rudder which gives flatter turns that are more stable.
Still the machine has far from hands off stability. It must be controlled all the time. This is something that surprises me. If it is left alone it will roll either to the right or to the left. It would spiral to ground if it did not receive the right correction. So it is time for me to find out how to improve lateral stability.
After having flown all kinds of ordinary RC airplanes for 40 years it is a new and thrilling experience to fly an autogyro. And I am glad I fly it standing on the ground and not sitting in it. I wound never thrust one.
/PO

I don't know what your problem could be as I am also a newcomer to autogyro flying I have been flying one for only 3 years now My flying partner and I both have Kellets I have been the test pilot for both of them since I got mine flying first. Both of them were stable and will fly hands off for considerable distance. My only thought on the subject is the servo that controls right and left tilt. I couldn't get good performance until I switched to a VERY powerful Digital servo A digital servo has something called holding power This prevents the arm from movement when you are not sending a signal.I am using a Hitec 5735MG This unit has 18 kg of torque and 54 kg of holhing power I also have very heavy pushrods going up to the head and super heavy horns. The power of that spinning rotor is awesome I also use Lexan for the hinge material as it is stiffer than polyproplene which was in the kit. I talking about the hinge for the head not where the blades are attached. The Kellet has the top part of the pylon hinged thats where I use the Lexan. If your blades are not quite balance they could be shaking and the servo is not quite sturdy enough to hold. My Kellet is quite responsive and could probably use some transmitter adjustments (exponential ) but I'm used to it

I use a Hitech 545. The weight of the machine is about 4 pounds so it is lighter and smaller than the Kellets. But maybe the servo is not strong enough. And the pushrod could definitely be made stiffer.
I will replace the pushrod and also try to rebalance the rotor. If it does not help I will try a stronger servo.
/PO

Hi Peso,
From your pics, it appears that your lateral sevo rod is pulling when turning left & pushing when turning right.
Could your pushrod be bending or buckling in that problematic right turn? You might want to try a stiffer push rod.

Good luck,
Bob Gardner

Hi Peso,
Another 2 cents worth>
Would believe right turn problem is mechanical, something is altering,
possible push rod, linkage or servo.
There is a servo developed especially for Gyro control and it is a jewel;
If desired take a look at it> FMA Direct model # PS905MBB
Stability>lateral area is important. You have an "open" work pylon? Try
enclosing the thing so that area wise it would be same as a"solid" pylon
Not mentioned is size and power of your gyro?
Good luck,

Hal [email protected]