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.
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Gyro stabilization for tailwheel aircraft
- Thread starter eignvctr
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eignvctr said:
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
- Thread starter
- #3
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.
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"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 ?
unless these gyros are different to momentum wheels ??
another day in paradise, or is paradise one day closer ?
btrueblood
Mechanical
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.
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 ...
reminding me of ...
Compositepro
Chemical
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.
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.
- Thread starter
- #11
3DDave said:
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.
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.
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- Thread starter
- #13
IRstuff said:
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.
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! faq731-376 forum1529 Entire Forum list
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.
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"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.
- Thread starter
- #16
3DDave said:
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.
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.
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.
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
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
"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?
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?
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!
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