Examples of motorized landing gear

[AeroFranz]

In the last ten years there have been proposals to equip single-aisle airliners with the equivalent of an on-board electric tug (Safran, Honeywell).

The only example i can think of of motorized/self-propelled landing gear is the one that was applied to the early Puma, discussed here .
Are there older examples of self-propelled landing gear having made it to the hardware, or at least serious proposal stage?

 

[Zoo Tycoon]

There’s been a few demonstrations;-
- Boeing did a “scrap heap lash up” using a 767 in the early noughties.
- a company called Wheel Tug has made a 737 creep along with a nose wheel electric motor;- they claimed to be 2 years away from production solution in 2007 and if you look at their website today they’re still only 2 years away.
- Airbus’s original “e-Fan” has one because it uses a bit less juice than squirting yourself along the taxiway with the fans

Aerojet proposed a C130 system in the early 70’s. It’s objective was to allow taxi on sandy unprepared surfaces without producing the large dust cloud which normally comes from running the props. It was pneumatically driven. I’m not sure if it got beyond the proposal stage but seems to have been the subject of quite detailed design work.

If you’re including wheel spin up devices then the only production one of those I’m aware of is the Vought Cutlass nose landing gear, again air driven. And before anyone gets excited, these systems are frequently proposed but are far more trouble than they’re worth, so are dumped in the early design phase.

 

[riggerrob]

Electrically-driven wheels make sense if you install electric brakes at the same time.
Some highway trucks have electric brakes, but they just dump braking energy overboard as heat. It would make more sense to use electric brakes to recharge batteries.

I can also predict ground-bound electric rugs being used to accelerate older airliners the first 100 knots. Automated tugs will then drive themselves back to the charging station.

 

[Zoo Tycoon]

It all sounds good until you do the maths.

BTW All of the aircraft electric brakes today just use electric actuators to squeeze a carbon friction pack.

 

[AeroFranz]

indeed, all the teams working on commercial airliner tugs seem to have gone on hiatus. I've heard the low gas prices are to blame, there isn't as much incentive to invest in the technology.
I had read about the Cutlass' spin up system (that airplane had so many weird solutions...). I think with the long, stalky nose gear, they were probably afraid it might snap off when instantaneously being accelerated upon contact with thee deck. I did not know about the C-130 system, i'll look it up!

 

[gtg947h]

I believe there are some early Citation models with a nosewheel spinup function as well, intended for landings on rough/gravel surfaces (to help reduce chances of fodding the engines). Not sure how successful it was.

 

[Grey Havoc]

I think it is still an option on some higher end business jets.

 

[riggerrob]

During the late 1940s the USAAF experimented with rubber flaps extending from sidewalks. The goal was to use airflow to pre-rotate tires before landing. They only tested the tires on a few transports/bombers, but soon dropped the experiment.
It seems that tire scrubbing provides significant braking ... helpful on landing.

 

[Zoo Tycoon]

The rubber flaps on a tyre contraption under went a single flight on a trials Tornado;- due to complex nature of the local air flow between the tyre and fuselage, one main landing gear wheel spun forward and the other backward! A very careful landing was made without incident, the TP refused anything further and thus the project ended...... these things are great until you do the maths and the devil is always in the detail.

 

[Fluff]

Launch sleds, are coming, as this is a long term site, lets come back in 3 years time.