ksimeon2000

Hi all, I have a question regarding gyro handling characteristics.

I've noticed that when performing sharp banking turns, my gyro will turn much tighter when turning into the direction of the rotation of the rotors (ex. a left turn on a rotor turning CCW). When performing a right turn on a CCW rotor, I can't seem to turn nearly as tightly, even when applying full up elevator. Additionally, the gyro seems to want to fall out of the turn when turning hard to the right.

The gyro in question is a pretty standard tractor gyro I designed myself. 3 bladed rotor with a delta offset flapping hinge rotor hub. Aileron and elevator controls are both on the rotor head. Powered by a Saito 40.

I've got about 8 hours of flight time in a real gyro (Aircommand tandem) and have noticed the same phenomenon, but to a much lesser degree. Turns into the direction of the rotor's rotation require little or no back cyclic (sometimes even some down cyclic), and turns against the rotor's rotation require a good bit of back cyclic.

Can anyone explain what causes this, and specifically what can be done to lessen this behaviour?

Thanks

ALbert.S

It is because of the gyroscopic forces that the spinning rotor imparts to the machine When you tilt the rotor to make a left turn the nose will come up and you will have to apply little or no elevator. Right turn will put the nose down and you will need elevator to keep a level attitude . This is for a rotor turning ccw looking from the rear.

boberos

I've built & flown a number of single rotor DC gyros like you mention & never noticed much difference in left or right turns.

Just avoid a sharp downwind turn at low altitude from a near hover.

Good luck,
Bob

floridagyro

Hi,

I have two sets of rotors, all from the same mold, and I bolted one set on a hub to turn CCW and the other set on a hub to turn CW. After several flights I determined that the gyro turns better to the left with the CCW blades and it turns a lot better to the left with the CW rotation. With the CW rotations, I had to help turn the gyro with rudder as the gyro had a hard time turning right by just tilting the head. I suspect it's because we're north of the equator!

Phil

boberos

Maybe that explains it Phil, as I am a loooong way north of the equator.
BTW, When you refer to blade direction, I assume you are looking down at the machine?

Bob G

tintrax

Being south of the equator and having only flown CCW rotation I can`t say I have noticed any great difference (if any) with left or rignt turns. Don`t use any offsets either ( tilt to one side or offset mast etc.). But I am wondering if your bathtub water really does go down the plughole the other way to ours!

tintrax

With reference to my letter above I am serious about asking which way the water goes down the plughole!! Here at 43 degrees SOUTH latitude it goes down the plughole clockwise. To make sure I put a small piece of paper in the tub and watched it circle the plughole before disappearing. I have heard many times that the northern & southern hemispheres have different plughole rotation - is it true? Maybe someone can humour me and try it!
What`s this got to do with autogyros? Maybe not much! Cheers from the south Pacific.

mnowell129

CCW in the northern hemisphere. Coriolis due to the earths rotation. For a mental understanding think of the north pole, earth is turning, still looking water is turning with the earth, When released in the plug hole it accelerates. Conservation of angular momemtum takes over at the end and the spin rate increases as the mass gets smaller. South pole the direction is inverted to the person standing there looking. Any point above the equator there is a component of this spin in the CCW direction. Opposite below the equator.
Has no effect on a gyrocopter unless you see a bear while you are out flying and the bear is white.

lnagel

Does this mean that the water will not spin if drained on the equator?

mnowell129

I think it spins either way. When can I expect my airline ticket to run first hand experiments?

boberos

You can trust me on this.

If you are flying your gyro & any colour bear shows up, the last thing on your mind will be the way water spins in the drain.

Run Like hell.
Bob

thgillard

Hi,

or confront him
[link=http://www.videofolie.com/voir.php?nom=bear.mpg&id=76]Bear[/link]

robobart

Greetings, all,
In re the left/right turning oddness, as an experienced heli and fixed wing pilot, I suggest that, in addition to the precession (Gyroscopic effect from the rotor, causing force to be shifted 90' in the direction of rotation) there might be an added effect from the precession of the thrust prop as well.

I am new to the autogyro thing, but have wanted one all my life, and finally acquired a 2D made by autos of Az.
I got it second or third hand, and no docs. Any input about the setup and behaviour of this model would be GREATLY appreciated!!
I am thrilled to see a group of folks with similar interest!!!
Robobart

floridagyro

Hi Robobart,

Welcome to the autogyro community.

I had a 2D and I would not consider it a good first gyro. Here are a couple of things that you can do to improve your odds of getting it flying. The rotor blades like to chop the tail off, even with the best gyro pilots and until you have a lot of experience with a gyro, ROG with this bird is difficult. I suggest hand launching and make sure it's headed straight into the wind. It's best in 5 to 7 mph wind and you will feel a good pull from the blades when it reaches autorotation. The 2D likes to tip over during ROG because of the large side profile and high stance. Also, get or make a set of SG6042 profile rotor blades to replace the ones that come with gyro. The SG6042 are much more efficient and they can be a couple of inches shorter and still provide plenty of lift also reducing the chance of chopping the tail off.

Good luck,

Phil

robobart

Howdy Phil, Thanks a million!!
I am thrilled to find someone who has one!!
The Mfgr is not very cooperative..
The stock blades are just flats, rounded on the front, wedged on the back, and my first point of action!!
I'll cut some new planer blades as soon as I get a prifile for the airfoil you mentioned, then I can whip out a few sets.
How much weight , if any have you added to the tips??
Should this be another thread??
Thanks again,
robobart
PS, Roger on the blades smacking the tail, but I think your fix might be a great idea, too.

Splinter Wood

"The 2D likes to tip over during ROG because of the large side profile and high stance."

I've seen this behavior before in a single rotor Gyro model. I was wondering what causes this and what would make a model behave better for ROG? I was thinking the rotor diameter was too large in ratio to the mass of the fuselage (I think 52" rotor and I'm guessing a total weight about 4.5 lbs).

Clint.

robobart

With regard to the tipping issue, and I am no expert at autos yet, I see 2 possible causes.
1, precession again, any pitching moment (caused by the airstream not meeting the rotor head- on) will be turned into rolling moment by the rotor.
2. The Center of Lift (CL) is so high, and therefore so far from the wheels, that the wheel drag can create a large rolling moment as well.

I guess they are not really separate issues, but additive effects.

On some RC planes, the gear are deliberately toed out several degrees to reduce the rolling moment in crosswind conditions. all the pics I've seen of Autos so far, the gear looks very parallel.

OK, simple question; Is "Hang Angle" ( I wanna say "Hangle") referring to the main rotor shaft line tilting back from vertical (Nose Up) when the auto is suspended by the rotor center???

If so, is it common to add LOTS of weight to the tail of a 2D?? I'm thinking my Russian MDS 40 is waayyy too heavy.
Robobart

soarrich

My Feedback: (98)

First, I'm not an expert gyro pilot, but I just had some thoughts on this as I was learning to ROG my PT Gyro.

The reason my PT gyro was tipping over was that the rotor was not in autorotation. If the rotor is in autorotation and going across the ground slowly the center of lift is pretty much at the hub. If the rotor is spinning, but not in autorotation the blade advancing into the wind is making almost all the lift. Watch and see if the gyro dosen't always tips toward the retreating blade.