Sprint Lite by Blades Over Me

gyroplanes

FAA DAR Gyropilot
Joined
Mar 18, 2004
Messages
6,086
Location
Lansing, Illinois (Chicago South Suburb)
Aircraft
(1) Air Command, (1) Barnett, (1) Air Command 2 place kit, (1) Sycamore gyro
Total Flight Time
2650
Looks like a Hornet (Gyrobee offspring) We had a similar one in our club and I can tell you that the round tube landing springs very well up and down, it springs equally well in fore and aft. Any time a wheel hits a stone, any strip of expansion joint on the runway or a clump of grass, the gyro will dart off in that direction. Unless the round tube is very stiff, it'll be a ride you won't forget. Tom
 

Doug Riley

Platinum Member
Joined
Jan 11, 2004
Messages
6,586
Gyro designers are always trying to fool Mother Nature by skimping on landing gear geometry. We all want to save money and weight.

So we see swing axles, springs with no damping and "ox cart" gear with no flex at all. All of these have drawbacks: they bounce you back up when you hit hard, or the gyro darts here and there as Tom says, or it gets into a divergent back-and forth "duck walk" that leads to a capsize. The VW beetle and Corvair tried simple swing axles, probably for the same reasons we do.

The "engineeringly correct" setup is what the designers of planes and gyros in the '30's used: triangulated (non-moving) outriggers with energy-dissipating friction shocks that go straight up and down, located at the outboard ends of the outriggers. The "friction" can be supplied either by solid materials rubbing on each other (even metal-on-metal will work, as on the Taggart Gyrobee), or internal friction of a liquid or gas being jammed through a small hole (oleo shocks, etc.). In either case, the energy of the gyro hitting the ground is partially converted into heat that bleeds off to the air. A spring without friction just stores the energy, then gives it all back again as a bounce.

Cessna leaf-spring gear works by using tire scrub as the friction device, unless the runway surface is too slippery to provide any friction.

Any gear setup that uses an axle pivoting around the center of the aircraft is going to produce one form or another of weird bouncing/steering effects. In extreme cases, these can tip the gyro over, leading to a blade-wrecking incident.

I once just barely saved my tandem Dominator from a "duck walk" triggered by a student's smackdown. It was close.
 

Brian Jackson

Platinum Member
Joined
Jul 17, 2004
Messages
3,284
Location
Hamburg, New Jersey USA
Aircraft
GyroBee Variant - Under Construction
I remember my car driving squirrly (sp?) with a slight misalignment. In one case the roads were wet and it would suddenly dart off to one side unexpectedly until I realized it tended to happen on the latter part of an S curve when the tires would reverse load to the opposite side of the car. I learned that the two sides were fighting each other and the tire with the greatest load got to determine which direction the car was headed that moment.

Without some kind of drag strut on the main gear, or designed-in stiffness in the fore/aft direction, I can imagine the lack of directional constraint could be a challenge on the ground.
 
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