Hanging a gyroplane.

[oldandnewbie]

I plan to hang test my gyroplane.

Hanging from the teeter bolt seems straight forward.

I do not have a second support point on the mast so need to balance on main wheels. The video (which is very informative) at

shows the wheel balancing.

Where should the control stick be positioned since this rotates the rotor's center of gravity forward/backward? I measured approximately 22 degrees, max rotation, on my gyroplane. Or is this insignificant?

Thank you.

 

[JohnS]

What you're wanting to do is center the stick in its travel with the rotor head in its level flight position, usually perpendicular to the mast angle. That is really the purpose of the hang test, to make sure you don't run out of stick travel fore or aft.

On the ground you set your stick in the center between where it hits its fore and aft stops (the stick really should have stops that it hits just before the head hits the stops, ideally). That's so you don't stress the controls at the travel limits. You'll adjust your push tubes to get the head in its normal straight level flight.

So you'll be in the seat holding the stick in the center while the gyro is hanging (lots of stick force, as you are moving the gross weight of the gyro). Then the mast or keel angle is measured. If it isn't spec, you would have to either add ballast to the nose or tail, move the seat or seat cushions to move your body fore or aft, or move the rotor head fore or aft on the head plates.

What complicates things is the mast is sometimes vertical while the head plates are angled. Most rotors fly at about 9 degrees straight and level. On the Bensens the mast was angled at 9 degrees relative to the keel so that in level flight the torque bar (that pivots on the pitch bolt) is 90 degrees to the mast. The rotor thrust is then pulling in line with the mast in level flight. The hang angle on the Bensen was measured on the mast at 1 to 3 degrees nose down.

Could vary from model to model. I only know Bensens. And recently Sparrowhawk, which I haven't figured out yet. But I know the basics and intent of the test.

Any critique or additions to this are welcome.
Trying to attach a pencil drawing but so far unable.

 

[JohnS]

 

[Vance]

I plan to hang test my gyroplane.

Hanging from the teeter bolt seems straight forward.

I do not have a second support point on the mast so need to balance on main wheels. The video (which is very informative) at

shows the wheel balancing.

Where should the control stick be positioned since this rotates the rotor's center of gravity forward/backward? I measured approximately 22 degrees, max rotation, on my gyroplane. Or is this insignificant?

Thank you.

Often people confuse a hang test and a double hang test.

John correctly describes the hang test as a way to center the controls and confirm that the rotor head is in the correct place.

It reads to me that you are also asking about a double hang test that is used to determine the location of the center of gravity as shown in the video you posted.

This requires a different hang point.

The center of gravity will always be directly beneath the single point that the gyroplane is being hung from.

The video details it well.

Your flight instructor should probably help you with this.

Good luck on you gyroplane adventure!

 

[Sv.grainne]

I recently did a hang test on my Aviomania. Single point from the teeter bolt with nothing touching the ground. Tested with minimum pilot weight and max and with no fuel and full tank.

 

[DavePA11]

Any photos sv.grainne?

 

[Sv.grainne]

Eric may have some. I've asked him to see if he still has them.

Bobby

 

[Sv.grainne]

Eric still had these. Image with me and a full tank of fuel and the hang angle measured per Aviomania instructions.

 

[Aviomania]

Bobby from the first picture i can see the torque bar is on the fwd stop.... the stick should have been locked in the middle... if it was in the midle the level was going to show 8-9 Degrees.

 

[Sv.grainne]

We did the test with the stick in the middle of travel, not sure exactly when the picture was taken. Just trying to illustrate the process.

 

[oldandnewbie]

Thank you all for your input.
In the video (

) I hear they are approximately '1/16 inch off' of Center of Gravity intersecting the Thrust Line.
Attached are my results. Big difference.
History: I saw my gyro fly at Mentone. I have since modified the pedals, made the front wheel 'free castering', added drum brakes, and I weigh approximately 20 Lbs less than previous owner.
Do I have problem? Or, do I just learn to control it.
Thank you.

 

[Vance]

If I am interpreting that correctly; that is about how high a Magni M16 tandem trainer’s thrust line is above the center of gravity and my opinion an M16 flies well.

They have a horizontal stabilizer with a lot of volume (square inches times the distance from the 25% chord line to the center of gravity).

Without a lot of horizontal stabilizer volume a gyroplane with a high thrust line is prone to a power push over.

I prefer a gyroplane that is closer to center line thrust or even with the thrust line below the center of gravity.

Anything you can do to reduce that high thrust line will make for less power-pitch coupling.

The simplest is usually to move the people up.

It is nice if your fuel in near the center of gravity so the center of gravity doesn’t change much as the fuel burns off.