Device to spin-up wheels?

BobS

BobS

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BobS
I listen to the "chirp" when my main gear touch down, even on the rare greaser, and can hear my tires wearing out with each landing. Has anybody ever heard of a device attached to the hub (retract only) that has small wind vanes attached that spin up the wheels when they are deployed in the airstream? Seems very simple and might drastically reduce tire wear.
 
how would you implement it? Using Airspeed? If you had a strong headwind, would the overspeed of the tire cause the same amount of damage as if it were still? or could it be worse?
 
I recall that this was experimented with and abandoned many years ago on airliners. I don't remember why it didn't work.
 
I mentioned this idea to my instructor back in the early '80's. He was retired then and had been an airline pilot that flew DC-3's and such at one time or another. He said that that idea was tested and it was found that the energy required for the initial spinup of the wheels on landing provided a significant reduction in landing roll. I don't have anything else to back this up, just some of the useless trivia I have heard throughout the years.
 
I have heard (but don't know) that airliners have automatic brake application to stop the wheel from rotating when retracting. Seems like this could be used in reverse to not let the wheels spin up until they are nearly fully extended. That would greatly limit the gyro effect.
 
Alan said:
I recall that this was experimented with and abandoned many years ago on airliners. I don't remember why it didn't work.
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I recall that too but I don't remember the details since a lot wasn't said at the time other than it wasn't feasable or there wasn't a significant advantage for some reason.

I have no experimental data however I'd think braking and ground ops (turning) would cause more tire wear than the initial spinup in the long run. Airliners like 747's and such with multiple axles on a single strut are likely to be brutal on the tires while turning on the ground.

There were experiments doing this in the 1950's and maybe even in the 1940's.
Interesting research on spin up forces: (I'll have to finish reading it later but it's interesting anyway)
http://naca.larc.nasa.gov/reports/1955/naca-report-1248/


Some practical questions come to mind though:
(1) What happens if one tire spins up and the other does not? (imagine you're in a taildragger at the time)
(2) What if one or both is put on backward and spins up the wrong way? (you just know some nincompoop will certainly figure out how to do mount it that way)
(3) There is significant angular momentum on the tire itself when it is spinning. What happens to the front (descending portion) of the tire on a really hard landing with all that vertical and additional rotational force driving the front of the tire into the ground creating a higher load directional change as it continues to rotate? What if the rotating tire is under-inflated (thus more deforming) during a hard landing? What if the tire is significantly worn?
(4) Do you always stop the wheels from rotating before retracting the gear? What if you raise a high velocity spinning tire into the well? (remember it now does not spin down after liftoff). Do you have to have deeper wells for the new hardware? Will the spin up vanes load up with water, snow and ice from runways and possibly freeze the gear in the wells?
(5) On fixed gear, are you planning on flying around all day with the tires spinning? If so, what if the tire is out of balance?

Just something to think about...

It's an interesting idea though. Practical? Not sure...though there doesn't seem to have been a lot of effort for half a century or more to use the idea.
 
How much are your tires? It was ~400-500 to replace the mains on our Bo. Seems like it would cost more to save the tires than the tires themselves!
 
Thanks everybody for the responses. I guess I'll have to keep my day job.
 
BobS said:
I listen to the "chirp" when my main gear touch down, even on the rare greaser
Click to expand...
If you do a real greaser, they don't chirp. IIRC, the chirp is caused by side loads. With no side load, and I think this has maybe only happened a couple of times to me, you just hear a hum as the the tires spin up.
 
BobS said:
I listen to the "chirp" when my main gear touch down, even on the rare greaser, and can hear my tires wearing out with each landing. Has anybody ever heard of a device attached to the hub (retract only) that has small wind vanes attached that spin up the wheels when they are deployed in the airstream? Seems very simple and might drastically reduce tire wear.
Click to expand...

Just land on the Grass! As the tires get close, the little grass stems must start the tires to spinning before touchdown because I never hear a "chirp" landing on grass.:rolleyes: (well, maybe once, but luckily the bird got out of the way)

Barb
 
One Short said:
Just land on the Grass! As the tires get close, the little grass stems must start the tires to spinning before touchdown because I never hear a "chirp" landing on grass.:rolleyes: (well, maybe once, but luckily the bird got out of the way)

Barb
Click to expand...

Hey, here's an idea, just make the first 1000 ft of runway kinda slippery. That way the tires spin up without wear as long as you don't float halfway down the runway. Of course there'd be some minor side effects like aborted takeoffs that run off the end, directional control issues if you touch down early, etc.
 
I know some folks that "spin their wheels" all the time!! Just have one of them aboard ;-).

Dave
 
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