Dave Wave

I have a Hawk 30 Heli I am learning to fly on.

I have started playing with learning autorotation.

When I flip the throttle hold, in a hover (engine to idle), I get about a 90 degree heading change from the loss of torque.

Is this normal?

I have a pizo gyro driving a normal (not super-fast) servo on the tail rotor.

Thanks,


-Dave

rotor09

Do you have the driven tail option on it?

What gyro and servo?

How do you have your tail mix set?

The stock Hawk does not have a driven tail. So if you hit throttle hold while in a hover, your gyro/servo may not react fast enough to hold the tail until all the torque disappears. If you do so while in forward flight, you will find that the vertical tail fin will have enough authority to keep everything in order as the tail will follow in the direction that the heli is flying after the T/R stops turning.

If you do want a driven tail you can add it as an option. But then if your servo/gyro combo is that bad, a driven tail might compound the issue.

Dave Wave

I bought the heli used so I am not sure on the drive option. How do I check if it has it?

The servo is a run-of-the-mill Hitec...HS485HB...gyro is a $25 Detrum GY48V

Right now I have no revomix.

Any other hints?

Thanks,


-Dave

rotor09

Other hints = get a better gyro.

BarracudaHockey

My Feedback: (11)

Turn the rotor head counter clockwise, does it turn?

If yes, then you have a driven tail, if not then you don't.

Aframomum

My Feedback: (10)

Is this the heli you have? [link=http://www.centuryheli.com/products/helikits/cn1000cHawkPro/index.htm?currentid=302]Hawk 30[/link] If so then it has a TT tail.

You may want to try upgrading the tail servo first, something faster and digital. I have a Detrum gyro on my EXI 450 (with a Futaba 9257 tail servo) and it does a decent job of holding so try the tail servo first and see if that makes a difference.

Mark

Rafael23cc

My Feedback: (6)

What does having a torque tube has to do with having a driven tail? the description on the link provided says nothing about a driven tail.

Dave Wave:

To elaborate on BH's comment, with the engine and radio off, turn the rotor head in both directions. If the tail rotor follows in both directions, then you have a driven tail (regardless of torque tube or not). If it follows in just one direction then you do not have a driven tail.

Rafael

Aframomum

My Feedback: (10)

Guess I misunderstood the definition of a driven tail...for my own intererst what is a driven tail?

Mark

Dave Wave

Not a driven tail.


So if I understand this right. If I am in a hover and loose the engine, the nose will swing and there is no way to correct it and I will have to land in the direction the nose ended up pointing. If I am in FF, the heli should weathervane and land straight ahead?


Thanks,

-Dave

rotordoc1

I have done thousands of autos, with many different helis in the past, that did not have a driven tail system. Most of these autos includes a 180 degree or 360 degree turn. The 180 degree auto was a maneuver required, at the end of class III AMA and FAI/F3C competition schedules, for many years, before any of our helis had driven tail systems. We even could complete 360 degree turning autos without a driven tail system. What a driven tail allowed us to do now, is backwards autos and to perform some 3D maneuvers, such as flips & pirouettes during the auto.

If yours turns 90 degrees from a hover auto, then I would suspect that one or both of the bearings that support the mainshaft are worn and/or your gyro/servo combination does not react fast enough to hold it as the tail rotor slows to a stop when the torque from the mainrotor disappears.

Of note, is that you can set any heli that does not have a driven tail system, to do simpler autos as if it does have one, by simply setting the throttle settings to a touch higher idle, so that the clutch engages just enough to turn the tail rotor slowly. This setting will be far lower then that which would engage the auto bearing that turns the main rotor. Consequently your main rotor would still be in the autorotative state, but your tail rotor would be now turning fast enough to provide basic t/r control.

This will not provide enough tail rotor to do 3D maneuvers or pirouettes while in the auto, but for standard autos, you will have more then enough t/r control to hold the heading you want into the wind.

rotordoc1

Basically yes, but as I said above with good bearings and a better gyro/servo combination (even the basic Futaba GY-401/S-9254 combo), then even from the hover there will not be much of a change in heading unless you loose to much main rotor speed.

BarracudaHockey

My Feedback: (11)

It drives the tail rotor from the main rotor/auto hub so you have tail rotor control during an auto.

A non-driven tail will stop in an auto to remove the drag of the tail drive system and allow the main rotor to maintain rpm longer.