Why They Don't Pre-Spin Airplane Wheels on Landing

A common question people ask, "is why they can’t put motors in the wheels or wind vanes on the tires or rims, to have them already rotating up to landing speed so they do not skid and leave behind rubber."

The idea of putting motors in the wheels or wind vanes on the tires to get them rotating up to landing speed before touchdown has been around sing the 1940's and there are a vast array of patents on different designs of wind vanes on tires.

This video answers that question and explains why it's not practical.

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[FusionAviation]

I hope this video clearly and fully answers everyone's question of *"why can’t they put motors in the wheels or wind vanes on the tires or rims, to have them already rotating up to landing speed so they do not skid and leave behind rubber."*

[firstlast-tydi]

"Every pound or half a kilogram of weight removed from an aircraft can save up to 11, 000 gallons of fuel annually for long-haul flights." You had better check you numbers! In 2005 I was a designer on the Airbus A380. Our weight/cost trade estimate was $500/lb./yr. I don't think that figure could have increased by 8800% in the last 19 years.

[philthycat]

Make Runways out of rubber and airplane tyres out of concrete. Problem solved.

[fredericlepeltier]

FYI : The F7U Cutlass, a late 50s US navy fighter had a pre-spin system for its front wheel.
Because it was long and very thin, its front landing gear leg would break upon hitting the deck on arrested carrier landings (faster and more violent than "normal" runway landings).
The solution was to run a air hose from one stage of the reactor compressor along the front leg to a vent and blast the front wheel with compressed air to pre-spin it.

[kazimir]

Everyone says it's not viable until someone makes it viable

[mikespencer]

Retired Airline Captain, there was a retrofit kit to a small private jet known as a Cessna Citation that would "spin up" just the nose wheel. That aircraft had just a single wheel assembly for the nose gear as most commercial jets usually have two wheel assemblies. But it was used for dirt field operations as a spinning wheel would be less prone to throwing up dust, rocks, and other debris when it touched down at speed. Think of a shovel being thrown into a rock pile at a high speed as opposed to a lower speed? The engines of the Citation were mounted towards the back of the plane on the fuselage and not under the wings. Just like chines on a tire for water, but that's another subject for another vid!

[tedsmith]

Having changed a LOT of 747 wheels, I can tell you that you cannot 'spin' a wheel just by hand. There is so much drag from the brake that you simply cannot get the wheel to keep turning after you give it even a hefty spin. It stops as soon as you stop pushing. The loads involved are considerable.

[johnlannigan]

As an engineer, I could pick holes on most of the arguments against in this video. This video was narrated from the against motors/vanes viewpoints.

[WaffleStaffel]

Funny, this was my first thought too. Every counter argument checks out except one- Firestone/Goodyear aren't going to gain a competitive edge by selling *less* rubber...

[ghostrider-beek]

not just about rubber - the shock of 0m/s to 75m/s in a second, is a huge jolt to the entire undercarriage - having wheels spin at even 40m/s would significantly reduce shock loads on the MLG and NLG.

The a380 for eg. is notorious for high speed vibrations in the truck, as the wheels spin up initially.

[LostsTVandRadio]

A much more elegant solution would be to pre-spin the runway!

[Thaihandmade-wdmh]

Am I the only one that *loves* watching commercial landing gear in slow-mo like this? I could watch an hour of it non-stop.

[mrkhoros]

I was expecting to be convinced by the explaination but I wasn't. Adding vane to the tires may not bring them to the landing speed but it sure helps by some percentages. Still makes me wonder why they haven't done it.

[markg]

Another thing to think about. The whole idea of the deceleration of landing is the need to remove a tremendous amount of energy from the system. If you spin the wheels before landing, you are adding tremendous amount of energy that now has to be removed during the stop. And adding weight in the apparatus to do so.

[no-damn-alias]

Vanes wouldn't need to fully spin up the tyres. Small passiv systems would be more than enough, simply avoiding flat spots and thus increasing service life of expensive tyres and slighty reducing rubber on the runway but why would the airline care about rubber on the runway?

Also the brakes are more than powerfull enough to stop free spining wheels even with those vanes on them!

[BB-smey]

Pre-spin them in the landing bay using compressed air provided (possibly diverted from the engines).

[vkvsp]

You mentioned the gyroscopic forces on the gear when it's retracting, there's also the centrifugal force of a spinning tyre. This can cause the tyre to expand just enough that it won't fit into the gear bay, or worse, make it jam. One of the first things a new pilot is taught, is to apply the brakes when the aircraft gets airborne, to stop the wheels spinning if they're going to be retracted.

[natehill]

Motors seem too heavy and unreliable, but vanes seems like a great idea. They dont have to spin all the way to aircraft speed, while that would be ideal, any speed difference would decrease rubber transfer. And you tap the brakes on takeoff when you retract regardless, particularly in bad weather.

And its not just savings in tires, its savings in closing runways to remove the rubber.

[shaymcquaid]

As an lifelong airliner mechanic I always wondered this exact thing. Thank you.

[sillybobthorton]

If the taxiing caused more wear on the tires than landing you would see them clearing rubber off the taxi ways, it’s the same as someone burning out in their car, the rubber left on the ground does more damage to the tires than them driving it around all day. Also there are ways of attaching canes to tires that do not require new molds to be made, such as bonding them to the tires after molding