8
$\begingroup$

I was reading answers to this question: How long do airliner tires last? Can this be improved? and it seems to be reasonable to keep things simple and rethread tires instead of designing motors to spin them up.

However, what if one was to implement a simple aluminum housing like the one in the drawing below which will provide the following benefit.

  1. When gear is deployed, due to friction of air only on the exposed part of tire thread, tire will spin up on it's own.

Has this ever been considered? Why would this kind of design work/not work for large airliners?

NOTE: the inside of the wheels are open for cooling purposes as well as various ducts can be incorporated for efficient cooling of the brakes.

enter image description here

$\endgroup$
  • 2
    $\begingroup$ "Has this ever been considered? " -> this type of wheel cover was common among aircraft with fixed undercarriage of the 1930's. Try: Fokker D.XXI, Fokker F.32, Junkers Ju 87, Mitsubishi A5M and many others. Seems to have disappeared with retracting undercarriage. $\endgroup$ – ALAN WARD Jul 30 '15 at 21:21
  • 1
    $\begingroup$ Yes, that makes sense when entire flight gear is deployed since it's fixed. What I mean is using similar approach to promote tire spin up. $\endgroup$ – Alexus Jul 30 '15 at 21:24
  • 2
    $\begingroup$ This may interest you: US patent 6,032,900 google.com/patents/US6032900 (consider also previous patents cited in the text) $\endgroup$ – ALAN WARD Jul 30 '15 at 21:31
  • $\begingroup$ Research paper out of Embry-Riddle: commons.erau.edu/cgi/… "The work performed in this study strongly suggests that a wheel spinup device can improve the life of heavy aircraft main landing gear tires." $\endgroup$ – Canuk Mar 4 '16 at 6:34
7
$\begingroup$

Check out this answer to a similar question. What it boils down to is that pre spinning gear has been looked into but there are implications of spinning up that kind of mass. The rotational inertia created created by doing so effects the handling of the aircraft. On a similar note its often easier to have a simple part that wears out and needs to be replaced often (like a tire) than a complex part that needs maintenance and is more likely to be problematic.

The part you describe is pretty common on small aircraft to reduce drag over the wheels. As far as I know it does not aid in spinning the tires. Since the tires are more or less flush the air simply flows over them.
enter image description here

For what its worth these boots also can get in the way. If the plane lands hard the tires will balloon out and rub up agains the sides of the boot (depending on the tolerances) this may break the boot the tire or both.

$\endgroup$
  • $\begingroup$ Got it, the gyroscopic force is the key :D $\endgroup$ – Alexus Jul 30 '15 at 23:11
  • 1
    $\begingroup$ "boots" = wheel pants. Re: trade-offs related to "pre-spinning", I would suggest cost, weight, and reliability - all favour "let contact with the ground bring them up to speed". $\endgroup$ – Anthony X Jul 31 '15 at 0:58
  • $\begingroup$ For the spinning wheels due to airflow, this question may help. $\endgroup$ – Manu H Mar 21 '16 at 21:29
3
$\begingroup$

My uncle told me the Air Force tried this in the 60's on some heavy aircraft but stopped testing for two reasons, first eventually someone would put them on backwards with obvious disastrous results, and secondly, an aircraft actually benefits from the initial braking impact that spinning the tires up gives it.

On smaller aircraft its helpful to get rid of that little bit of speed to help pilot transition from flight to "down and rolling". It reduces the aircrafts tendency to bounce back into the air. After a few thousand hours of flight time myself, I believe he was right.

Additionally, I have seen smaller tires (tailwheels) spinning in flight on some aircraft as air sped past their bottom surfaces, I have not seen this tendency on main gear(faired or not).

$\endgroup$
0
$\begingroup$

This was tried in the '50s by providing small flaps on the tires which caught the air and spun the tire prior to touchdown. Medium and mixed success. Don't know why it never caught on.

$\endgroup$
  • 6
    $\begingroup$ You may add references to improve your answer. Doing so increases your answer's quality and provides further readings and a set of links for those wanting to know more. $\endgroup$ – Manu H Mar 21 '16 at 21:27
  • $\begingroup$ Given that the question is asking why such a system never caught on, an answer saying that you don't know is unlikely to be considered useful. $\endgroup$ – anaximander Jun 2 '17 at 10:46

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.