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Gyro stabilization for tailwheel aircraft

Gyro stabilization for tailwheel aircraft

Gyro stabilization for tailwheel aircraft

(OP)
I'm wondering if anyone has done work on trying to stabilize landing and takeoff characteristics of tailwheel aircraft using some kind of gyro technique. I've seen some folks on RC forums talk about having a little device that is based on solid state gyros managing the control surfaces to help with stability of their aircraft and I've seen mention that it is helpful in preventing ground loops on tailwheel RC planes. Ground looping is a particularly nasty problem in tailwheel aircraft and I was wondering if gyros have been considered for actual tailwheel aircraft and not just RC. The control surface interaction would be one way of preventing ground loops however another might be to have an inertially heavy gyro spinning at high RPM in the rear of the airplane and locked to a position for stable landing and take off. I haven't done the math on whether the weight and rpm of such a thing would be practical but even if it isn't, the control surface method could be very useful too and involve reasonable weight additions I'm sure.

RE: Gyro stabilization for tailwheel aircraft

Quote (eignvctr)

I haven't done the math on whether the weight and rpm of such a thing would be practical

For an aircraft carrying people, you can be sure that someone has done the math, and shown that it isn't practical. And the gyro-driven rudder control sounds like it would have frightening failure modes.

Microelectronic gyros like the one in your cell phone are plenty sensitive and responsive enough to do what you want.
This is essentially how helicopter drones orient themselves, now. If you are a RC builder yourself, then all the pieces are available for you to try it on your own models.
If fixed-wing RC tail-dragger model builders won't try it on their models, then all their talk isn't worth much.
Weight isn't the issue: nobody would try this with mechanical gyros.

STF

RE: Gyro stabilization for tailwheel aircraft

(OP)

Quote (SparWeb)

Weight isn't the issue: nobody would try this with mechanical gyros.

Apparently NASA did. Link I just found that info today, and while it isn't for tailwheel aircraft it at least suggests that it is possible. Still perhaps not practical.

RE: Gyro stabilization for tailwheel aircraft

That link is not for aircraft at all. No aerodynamic forces anywhere.

RE: Gyro stabilization for tailwheel aircraft

CMGs are essentially only applicable to spacecraft. They are used to change the attitude of the spacecraft, without burning fuel, which for a reasonably sized solar array, can be sustained indefinitely. This is not the same as using a CMG to bleed some sort of angular correction; a typical CMG only allows for a few degrees/second of attitude rate.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: Gyro stabilization for tailwheel aircraft

"indefinitely" ? ... surely if they're doing some work (stabilizing the satellite) there must be some loss of energy = rotation speed ?

unless these gyros are different to momentum wheels ??

another day in paradise, or is paradise one day closer ?

RE: Gyro stabilization for tailwheel aircraft

Yes, they consume power even running in steady state (not producing control moments). The typical comsat has tidal forces acting on it requiring some of the rcs wheels to continuously torque against it requiring a slow but steady acceleration of the wheels, and must be de-saturated periodically (spun back down to near zero rpm by using reaction control thrusters to create opposing moments). Ain't nothing for free. Magnetic torque bars can also be used on lower orbiting craft, reacting against Earth's magnetic field - but only in certain directions. And they consume power too.

RE: Gyro stabilization for tailwheel aircraft

Since the net momentum change is zero, there is no net work done on the satellite. It's like how a skater can change their moment of inertia to increase and decrease their rotation rate, but the energy of spinning is constant, save for friction losses.

reminding me of ...

RE: Gyro stabilization for tailwheel aircraft

Changing a satellite's attitude does require acceleration and deceleration, so energy is definitely consumed. The net momentum change of a car after a trip to the store is also zero. You could say all the losses are friction losses. I guess that is the point of your comic.

However, reaction control systems that only turn the satellite use electric motors to spin a rotating mass. The energy comes from solar panels, not from stored fuel. That is the main point.

RE: Gyro stabilization for tailwheel aircraft

maintaining an attitude (against external disturbances) also requires work/energy.

another day in paradise, or is paradise one day closer ?

RE: Gyro stabilization for tailwheel aircraft

(OP)

Quote (3DDave)

That link is not for aircraft at all. No aerodynamic forces anywhere.

Ground looping in a tailwheel aircraft is largely a non-aerodynamic event. In a ground loop, full rudder deflection combined with maximum differential braking have lost the battle and inertia takes over for the ensuing unfortunate dynamic proceedings. That is why I thought mechanical gyro stabilization could be a solution. The Wiki article mentions thousands of newton-meters of torque from a 100kg gyro powered by a few hundred watts. That weight is a little high for smaller aircraft but depending on how many "thousands" of newton-meters, it is at least in the correct order of magnitude of adequate resistive torque to resist a ground loop in a small aircraft, one might think.

RE: Gyro stabilization for tailwheel aircraft

I think that as wit any engineering problem, one needs to determine whether the cure is worse than the disease. A resisting force to prevent yawing also resists turning, potentially making the aircraft difficult, if not impossible, to steer. And when do you spin this puppy up? Having it on all the time is impractical, and adding 100 kg to the tail is bad for aerodynamics. If you turn it on right before landing, you add several more things that the pilot has to worry about and checklist in an already overworking and stressful environment.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Gyro stabilization for tailwheel aircraft

(OP)

Quote (IRstuff)

I think that as wit any engineering problem, one needs to determine whether the cure is worse than the disease.

Agree. There is no doubt that something like what I'm thinking would be a highly engineered addition rather than just "toss it in the back, spin it up and go". For instance it may need a freely pivoting rotational axis until the wheels contact the runway - possibly an automated locking event. Then it may still need a limited amount of axial pivoting for minor corrections. It would then need to release the axis once the wheel speed dropped below some practical value for subsequent taxiing. So yes, nothing simple to be sure.

RE: Gyro stabilization for tailwheel aircraft

Actually, that wasn't what I was referring to.

Rather, the question needs to start with whether this is actually a sufficiently serious enough of a problem to warrant trying to fix it. There are lots of problems that could be solved, but shouldn't, and vice-versa. Only when the problem should be solved, and can, should one proceed. There are few things more sad than a solution looking for a problem.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: Gyro stabilization for tailwheel aircraft

"Ground looping in a tailwheel aircraft is largely a non-aerodynamic event." It is a very aerodynamic event due to differential angle of attack and differential air velocity on the wings which will supply as much torque as required to continue the event. Misunderstanding the cause will mislead any solution.

RE: Gyro stabilization for tailwheel aircraft

(OP)

Quote (3DDave)

It is a very aerodynamic event due to differential angle of attack and differential air velocity on the wings which will supply as much torque as required to continue the event.

I see what you are saying and I didn't say entirely non-aerodynamic. But I'm not convinced that the differential angle of attack of the wings dominates the phenomenon to any degree though. Do you have any references on that matter? It seems intuitive to me that you could take off the wings entirely and still ground loop just fine due to the CG being behind the front wheels and steering control coming from the rear.

RE: Gyro stabilization for tailwheel aircraft

eignvctr,
The thing here is to prevent any excursion from a straight line before it develops. That is why a tailwheel pilot is trained to notice these excursions , and apply corrective action before they develop. How is your device going to differentiate between the jiggling and bumping a tail wheel on the ground endures, and the actual excursion from a straight line, or intended curve?
B.E.

You are judged not by what you know, but by what you can do.

RE: Gyro stabilization for tailwheel aircraft

What? I completely misunderstood on my first reading. You mean to use a gyroscope to mechanically counteract the rotation moment?
Wow, I'm very skeptical now.

I thought you meant using a gyroscopic sensor (low mass) to produce a digital signal which would be processed into an actuator control. The actuator would be directed to the braking and rudder inputs that are causing the ground loop and prevent it from developing into a ground loop. Like traction control or anti-lock brakes in an automobile. A system like this to counteract a ground loop is at least possible/conceivable.

Carrying a mechanical gyroscope in the aircraft with enough angular momentum to oppose a ground loop has even more frightening failure modes!

STF

RE: Gyro stabilization for tailwheel aircraft

"Ground looping is a particularly nasty problem in tailwheel aircraft " - been flying tailwheel aircraft for almost 50 years, most in tailwheel aircraft. I don't consider ground loops to be a real problem. I think you are trying to find a solution to a problem that really doesn't exist.

The majority of tailwheel aircraft are light single engine aircraft, many with no electrical power and minimal weight carrying capability. Cubs and Champs and Tcrafts designed and built in the '30s when the average person weighed less than 170 lbs can barely fit two people of the average size today and still be LEGAL. Don't try and reinvent the wheel here. Even the larger tailwheel airplanes, how often do you ever hear of a DC-3 ground looping?

RE: Gyro stabilization for tailwheel aircraft

helicopters and autogyros take advantage of gyroscopic forces for stability right? I've thought much about (and watched a lot of RC freakreations on youtube) utilizing wheels or other non-typical rotating aerodynamic surfaces as lateral/directional stability a lot (plus a little stored flywheel energy). One guys uses spinning KFC buckets for lift in lieu of wings. First in my mind as stated here is frightening failure modes! Second obstacle is weight. To offset weight and do something like this would I think require a whole aircraft designed around the concept, like a propelled, controlled frisbee disc or aerobie ring with a payload. Failure modes of something like that are indeed scary!

RE: Gyro stabilization for tailwheel aircraft

"...some kind of gyro technique..."

Tiny gyro sensors could be used to provide a pilot-assistance 'Stability Program' system, similar to the way car anti-skid systems work. Sensors, software and some gentle mechanical assistance with the controls, especially individual wheel brakes for tail dragging aircraft.

Probably should *not* be Full Authority, but limited by design to small helpful inputs. Provide feedback to the pilot to let the system manoeuvre to recover, as opposed to them fighting each other. (Full Safety Analysis goes here.)

--

Most aircraft already have large, heavy, rapidly rotating things in the form of engines and blades. There's almost certainly not enough weight capacity to add one more.

RE: Gyro stabilization for tailwheel aircraft

While I don’t fly full size aircraft I do see tailwheel lock used on them.
My favorite WW II airplane is the Corsair. In the RC modeling world back some 30 years ago, it was unheard of to use a gyro in fixed wing rc models.

At the time I flew with a couple helicopter guys who had the new gyros on the helix. One of them challenged me to try one on the Corsair. As the real ones were noted for torque roll the big 8’ span RC models displayed the same thing. As well as severe weathervane into cross winds. Most of these models crashed sooner or later taking off or landing.

The heli guy said if the gyro worked I could keep it. These were expensive devices back then. So we installed it on my big Corsair. By tying it to the landing gear it would turn off automatically when the gear retracted, thus did not affect normal flight.

The thing worked amazingly well. We tested it in as much as 30 mph crosswinds. It steered both the rudder and tail wheel. In windy conditions I simply held the tail on the ground a little longer then as the tail came up the gyro provided rudder as required.

Later I added the gyro to a separate channel so I could use it in normal flight. At the top of loops the plane would roll out sometimes but the gyro corrected this. At a lower rate it also corrected the fish tailing common to most Corsair modeled.

The bottom line is that my Corsair survived for 13 years of flying before I gave it to my son. It is still around being restored.

So with modern technology I surely could see these on full scale planes.

RE: Gyro stabilization for tailwheel aircraft

eignvctr,

Quite a few years ago, I was asked to investigate a mechanical gyro in an airborne optical sensor. I determined that the gyro needed to be large in relation to the sensor, and/or very high revving. I observed that the gyro does not prevent rotation. It drastically increases the moment of inertia. If your gyro stabilized aircraft gets crooked on the way in, you are going to have fun getting it straightened out again.

--
JHG

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