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The Socata TB10 checklist indicates that you should touch the brakes after lift-off. I assume this is to stop the wheels from turning, but why?

In a retractable gear aircraft this would make sense to avoid using anything in the wheel-well to stop the wheels and potentially causing damage or generate heat (as a side note, I think some airliners actually have brake-pads in the wheel wells for this purpose). However, the TB10 is not equipped with retractable gear.

The TB10 and TB20 are very similar, and it might be a case of copy & paste between the two POHs (the TB10 POH also lists V-speeds for "flaps and landing gear retracted").

Do spinning wheels have an adverse effect on aerodynamics (or handling in general)? I would assume, if anything, they'd produce less drag. And as a cherry on top, I'd also assume they'd start spinning again fairly quickly, as only the lower part of the wheels are protruding out in to the air flow.

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  • $\begingroup$ An instructor I sometimes fly with constantly taps the brakes just after take-off when we fly in my 182. His reason is mainly out of habit; he's a former regional carrier ATP. $\endgroup$
    – mah
    May 4, 2014 at 21:19
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    $\begingroup$ depending on the condition of the runway (grass, dirt) and tires, rotating wheels can induce a little shaking in a DA-20. As a rule, I always step on the brakes after lift off to stop that annoying vibration $\endgroup$
    – Radu094
    May 4, 2014 at 21:26
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    $\begingroup$ I'll tap the brakes in the Cherokee if I feel a vibration that I think is related to the gear (though the one you're most likely to feel is the nose wheel, which has no brake...) - If that stops the vibration I know the main wheel bearings may need attention. $\endgroup$
    – voretaq7
    May 4, 2014 at 23:12
  • $\begingroup$ Maybe it's in case you install an STC for retractable gear? $\endgroup$
    – Vikki
    Oct 23, 2019 at 2:47

7 Answers 7

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This answer to another question has a link suggesting that the spinning wheels may be sufficiently large gyroscopes to affect handling of the aircraft. That was however on a larger aircraft and higher speed (Lockheed Constellation). I don't know whether that effect would be observable on TB10.

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On a Cessna 172, spinning wheels do create vibrations. Once the brakes are hit the vibrations stop. It could be due to the wheel balancing.

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  • $\begingroup$ This would be my answer. To stop the vibrations that can especially agitate unknowing passengers. $\endgroup$
    – Magnetoz
    May 5, 2014 at 15:40
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    $\begingroup$ Can you do more to convince readers that on a Cessna 172, spinning wheels do create vibrations? Is this documented somewhere? $\endgroup$
    – user2168
    May 5, 2014 at 22:47
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    $\begingroup$ @user2168 - get in a C172, ask the pilot not to touch the brakes. Once you feel the vibrations, ask him to tap the brakes, note that the vibrations stop. Voila, documentation. $\endgroup$
    – Jon Story
    Feb 6, 2015 at 14:26
  • $\begingroup$ Spinning wheels did cause vibrations on the 172s I flew. (Slightly out of balance wheels, I suppose.) It's always good to eliminate benign causes of noise, so they don't potentially mask noises that require attention. It's always good to know the cause of any noise or vibration. $\endgroup$
    – O. Jones
    Jun 23, 2017 at 11:33
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My initial hunch tells me that the reason for this is a bit of angular momentum.

Remember back when you were a kid, first learning to ride a bike? At some point you realized that the more speed you have, the more stable you are on your bicycle. This is because of angular momentum.

So imagine your up in the air, and you have to wheels rotating at 75 rpm (assuming a takeoff speed of 55KIAS, no headwind, and a tire diameter of 18 inches). You have a decent amount of angular momentum fighting any maneuver that the aircraft wants to make.

Consistency is key in safety in aviation. The difference in ground speed for a takeoff could vary from the Vr KIAS ± max head/tail wind. That's enough to significantly alter the dynamics of a maneuver.

--EDIT--

If you want to know how much you are affected by this angular momentum, check out the question I posted on the physics stack exchange.

https://physics.stackexchange.com/questions/111353/what-is-the-inertia-caused-by-angular-momentum-when-twisted-on-its-rotating-axi/111422

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    $\begingroup$ To the person who downvoted: why? Care to share? $\endgroup$
    – OneChillDude
    May 5, 2014 at 2:59
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    $\begingroup$ I think this answer could be improved by doing more to convince us that "that's enough to significantly alter the dynamics of a maneuver". How much angular momentum is there? How relevant is that to flight maneuvers? Does any reliable source agree with you? $\endgroup$
    – user2168
    May 5, 2014 at 3:52
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    $\begingroup$ Actually, gyroscopic effects make very little contribution to the stability of bicycles, as shown by experiments by David Jones in the late 1960s. For more details, see Lowell and McKell, *The Stability of Bicycles (American Journal of Physics, vol 50, no 12, pp. 1106-12, 1982; PDF). $\endgroup$
    – David Richerby
    May 5, 2014 at 18:46
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    $\begingroup$ Physics SE on the subject of bycicle stability: little to do with gyroscopic inertia. $\endgroup$
    – E.P.
    Jul 3, 2016 at 1:31
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Spinning wheels are not a problem in fixed undercarriage aircraft, there's no good reason to tap the brakes after takeoff if the gear is nailed down. I suspect you answered your own question when you theorized that they may have simply copied that part of the manual.

From a wear perspective you may save some wear on the bearings by stopping the wheels spinning, but since you are using the brake pads to do it it's likely less overall wear just to let them stop naturally.

CLimbout is a busy time, anything that adds workload without a benefit shouldn't be on a checklist. I'd say you are probably safe to ignore that in a TB-10, however that is just my opinion and it may be worth contacting a TB-10 club and asking them what they think.

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It's strictly done to stop the wheels from vibrating as they wind down, which can scare the pax and sometimes the pilot at first. Light aircraft wheels don't get any kind of post-install mass balance until they get to a certain size (and even large wheel assemblies on airliners are only statically balanced in a static rig they way motorcycle tires are done - you won't find any automotive style wheel balancers at an aircraft shop).

For light aircraft tires, there is a marked light spot (a yellow or red dot) on the tire that you put next to the air valve when you mount the tire in the wheel halves. That gets you fairly close to balance, but they are never perfectly balanced, and this isn't really a problem except when they are spinning freely on the spring of the gear leg, where they will vibrate in phase as the spin rpm matches the natural frequency of the gear assembly slowing down. This is most pronounced on spring steel gear legs.

Airliners do it automatically on the main gears by applying the brakes (vibrating main gear tires on spin down would really terrify the pax!), and nose wheels are done by snubber pads in the gear well that rub on the tread as the wheels come up. It's not unusual for flight crews to snag nose gear tires that vibrate like crazy before the snubber blocks stop the wheels.

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  • $\begingroup$ I think you have the red dot info backward. "Set the outboard half in the tire. Align red-dot on tire with the wheel valve or wheel's heaviest point if indicated. Align bolt holes in accordance with manufacturer's instructions." bridgestone.com/products/speciality_tires/aircraft/candm/… $\endgroup$
    – JScarry
    Nov 21, 2020 at 18:46
  • $\begingroup$ Yeah a little mental carelessness. Fixed thanks. $\endgroup$
    – John K
    Nov 21, 2020 at 21:39
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1) The spinning wheels will cause vibrations until they are stopped.

2) It is good practice to stop your wheel after you lift off due to flailing tread. Flailing tread can do a lot of damage, especially if it becomes thrown tread. After you stop the tire rotation, it just becomes "hanging tread" and will not do any damage. This is why commercial airlines have systems in place to automatically apply the brakes on retraction and the nose tires get pressed against "spin brakes." Also by learning the practice with fixed gear aircraft, it is more likely to be second nature when you move up to retractable gear.

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I was told to do the same thing. They said that once the wheels started spinning (from take-off) they often didn't stop: the air flow tends to keep them going once they are spinning. It has a slight effect on bearing wear.

I just thought a 2nd reason now: when you land if they are already spinning, then when you land, they don't need anymore energy to get up to speed. But you'd rather they DID require some energy, that would help you slow down. Might be quite small though, I haven't calculated it.

But I doubt that it's a big deal either way.

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  • $\begingroup$ Aircraft tires on most fixed gear planes generally DO stop spinning pretty quickly. Fly or ride along in an aircraft with wheels visible from the cockpit and you will see them stop pretty soon after liftoff. $\endgroup$
    – J W
    Feb 7, 2016 at 20:15

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