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.
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.