Will landings be always smoother if wheels rotate at the aircraft ground speed?
Posted by Silly-Low6019@reddit | aviation | View on Reddit | 11 comments
Silly question. Landings are difficult even for an experienced pilot , not only do you require the right speed, flair up the aircraft,but also the fact that wheels are stationary and cause a lot of friction upon impact. Now what if the wheels were rotating at the exact ground speed (at the right rom to match ground speed ) , will la dings be smoother?
Have any aircraft manufacturers tried this idea ?
jwardell@reddit
I actually proposed this feature when we were developing an aircraft with electrically driven wheels, it would essentially be a no-cost feature that would significantly reduce tire wear. But most aircraft do not have driven wheels, which would add a lot of weight and expense. So if it's not worth it to make the aircraft drive on the ground etc, it certainly isn't worth it for that small landing benefit.
greatlakesailors@reddit
The case for that might be different now that fuel is more expensive, high torque electric motors are much more compact, and new planes have powerful electrical systems replacing hydraulic & bleed air.
Think about the possible OpEx savings on a Dreamliner if it could taxi on the APU and wheel motors, without starting main engines or needing a pushback tug.
jwardell@reddit
Yep, it will take the airline industry a long time but there will be situations where it makes sense.
Swimming_Way_7372@reddit
" But most aircraft do not have driven wheels,...." which is why an airplane has no problem taking off on a treadmill.
agha0013@reddit
that really doesn't contribute much, the force of a huge and heavy aircraft settling on the runway is what you're feeling, not getting the wheels up to speed.
The best landing gear design for smooth landings is a trailing link design, which is not a great design for large airliners. Tends to be business jet class and smaller. It's a lot of the magic behind why PC-12 landings are incredibly smooth.
to replicate such a system on a big airliner would make a complex landing gear arrangement that is much heavier than it needs to be, which causes penalties in payload and range for a minimal benefit.
SRM_Thornfoot@reddit
It has been tried, but to save wear on tires not to smooth out landings. They used the airstream to spin the tires up. I guess it was not worth it since you don't see it used anywhere.
I do not think that the tire spinup on touchdown adds significantly to the landing feel.
I have found that the biggest contributers to a smooth landing are getting the nose pointing straight down the runway and having no drift as you touchdown. If you have those set up right even dropping in a solid plunker will feel smooth.
Cant_Work_On_Reddit@reddit
I hope this is a bot account
Silly-Low6019@reddit (OP)
Yes , spam from hell.
alzee76@reddit
They come up to speed almost immediately with a bit of heat and noise. I'd bet money "smoothness" felt by passengers is not affected in any meaningful way.
Ok_Rabbit5158@reddit
Just adding more stuff that would fail. In worst case, fail on one side only.
Cheetawolf@reddit
It would save in tire wear, but the equipment required to spin up the tires would add so much weight to the aircraft that fuel costs would more than outweigh the savings on tires.