Retractable gear questions

AggieMike88

AggieMike88

Touchdown! Greaser!
Joined
Jan 13, 2010
Messages
20,805
Location
Denton, TX
Display Name
Display name:
The original "I don't know it all" of aviation.
On my flight from DFW to DEN on an AAL Airbus, I was seated a row or two back from where the main gear is attached. As such, I could hear and feel the gear coming up including a rumble that might be the rotational speed of the wheels slowing down.

Q1 for our jet pilots: Is there a system that brings the wheel spin to a full stop before they are fully stowed? Or is the gear swing timing long enough for them to stop on their own? Or are the wheels still rotating once they are fully stowed?

Q2 for our GA pilots who fly a retract gear airplane: similar question for you... are the wheels still turning once they reach th stowed position? Does your POH indicate this is they way it should be? Or do you take an action to reduce or stop the wheel spin as the gear travels to the stowed position?
 
AggieMike88 said:
On my flight from DFW to DEN on an AAL Airbus, I was seated a row or two back from where the main gear is attached. As such, I could hear and feel the gear coming up including a rumble that might be the rotational speed of the wheels slowing down.

Q1 for our jet pilots: Is there a system that brings the wheel spin to a full stop before they are fully stowed? Or is the gear swing timing long enough for them to stop on their own? Or are the wheels still rotating once they are fully stowed?

Q2 for our GA pilots who fly a retract gear airplane: similar question for you... are the wheels still turning once they reach th stowed position? Does your POH indicate this is they way it should be? Or do you take an action to reduce or stop the wheel spin as the gear travels to the stowed position?
Click to expand...
Depends on the aircraft and which gear. Some automatically apply brake pressure and some have a stop plate. They spin for a while if they aren't stopped.
 
In my plane, there's no system to stop the tires from spinning. We do have a mechanism to straighten out the nose gear before it fully retracts and locks in place. Edit. Just double checked and we do have a system to activate brake control valves to stop the mains from spinning.
 
Last edited:
Cooter said:
Depends on the aircraft and which gear. Some automatically apply brake pressure and some have a stop plate. They spin for a while if they aren't stopped.
Click to expand...
Stop plate is an item in the gear well that rubs on the sidewall of the tire?
 
jordane93 said:
In my plane, there's no system to stop the tires from spinning. We do have a mechanism to straighten out the nose gear before it fully retracts and locks in place.
Click to expand...
Which plane? (And remind us who your flying for? I forgot)
 
Q2: I know a lot of peeps tap the brakes just prior to bringing the gear up. When I fly the lance I'm far more concerned with standing on the right rudder on takeoff than tapping the brakes.
 
As an has been said. Depends upon the aircraft as to whether it is automatic or via scrub blocks. My MD11 is auto for the mains but scrubber for the nose. That is the way it is for most transport category aircraft. On the DC 8 it was specifically mentioned in the manual to NOT touch the brakes as all were scrubbers. There is a tremendous amount of inertia with these big tires and you can actually spin the tire on the rim and let all the nitrogen out if you apply brakes too quickly. Thirty plus years of transports and I have a very hard time pushing the brakes on my Bonanza.
 
On typical transport category jets, brake pressure is applied automatically to the mains with weight off wheels and gear lever up.

The nose tires will typically be brought to a stop by the use of pads mounted to the top of the NLG wheel well that the tire tread (not sidewalls) rub on.
 
On the airliner type planes, I'm not sure what they may have, it may vary.
For corporate jets, it depends, some have a brake after retraction, some don't. There's a wide range of jets all the way from G-4's to simple little Citations. I don't normally hit the brakes after T.O., I let them spin down, shouldn't be an issue if they're in balance. On smaller piston planes, you can tap the brakes if you want to if it make you feel good. Of course if the nose wheel is out of balance you're going to feel it and there's no brake on that.
 
The 172RG and 182RG have to apply the brakes after take off to stop wheel rotation in their checklists.
 
Pilawt said:
I usually tap the brakes even in a fixed-gear, since the wheels are usually slightly out of balance and cause a slight wobble until they stop spinning.
Click to expand...
Ditto. Can't remember the last time, if ever, I flew a plane that had perfectly balanced tires.
 
AggieMike88 said:
Q2 for our GA pilots who fly a retract gear airplane: similar question for you... are the wheels still turning once they reach th stowed position? Does your POH indicate this is they way it should be? Or do you take an action to reduce or stop the wheel spin as the gear travels to the stowed position?
Click to expand...
Normal procedure from the POH that I always do is tap the brakes after breaking ground and then gear up. Cessna 310
 
The Navion has a rubber snubber that stops the rotation as the gear hits the well.
 
Yep in the A* best practice is to tap the brakes. Doesn't do anything for the nosewheel, of course.
 
When I was a kid, flying on a 707, once, when the gear came up there was a whomp, whomp, whomp with significant vibration directly below me. I looked across the aisle at my dad and could see concern in his face. He got up an went to the cockpit. When we arrived at our destination, fire engines were awaiting us, with no mishap. Most, if not all, modern airliners apply the brakes automatically with the gear retract cycle.
 
Pilawt said:
I usually tap the brakes even in a fixed-gear, since the wheels are usually slightly out of balance and cause a slight wobble until they stop spinning.
Click to expand...

If the plane has wheel pants, does the asymmetric exposure to the relative wind cause the wheels to rotate in-flight?

Naked wheels have symmetric exposure and aren't a concern, right?
 
asicer said:
If the plane has wheel pants, does the asymmetric exposure to the relative wind cause the wheels to rotate in-flight?

Naked wheels have symmetric exposure and aren't a concern, right?
Click to expand...

I can speak for Cirrus (and guess others may be the same) - there is enough designed in tension/friction in the bearings to stop the gear from spinning when in flight. It doesn't take that much since the tires are fairly aerodynamically slick.
 
asicer said:
If the plane has wheel pants, does the asymmetric exposure to the relative wind cause the wheels to rotate in-flight?
Click to expand...
Wheel pants have a nasty habit of getting jammed in the wheel wells on retracts.

Naked wheels have symmetric exposure and aren't a concern, right?
Click to expand...
Nothing is truly symmetric. It's not uncommon to look out and see a small amount of rotation from naked 172 wheels. However, most of the rotation of concern comes from being spun by the runway surface.
 
Sometimes the nosewheel doesn't stop spinning after retraction on the -38 and it makes for an interesting ride on takeoff. Feels like damn off-center washing machine. That pesky 165KCAS liftoff speed on initial takeoff :eek:
Mains stop rotating pretty quick on their own though.
 
AggieMike88 said:
On my flight from DFW to DEN on an AAL Airbus, I was seated a row or two back from where the main gear is attached. As such, I could hear and feel the gear coming up including a rumble that might be the rotational speed of the wheels slowing down.

Q1 for our jet pilots: Is there a system that brings the wheel spin to a full stop before they are fully stowed? Or is the gear swing timing long enough for them to stop on their own? Or are the wheels still rotating once they are fully stowed?

Q2 for our GA pilots who fly a retract gear airplane: similar question for you... are the wheels still turning once they reach th stowed position? Does your POH indicate this is they way it should be? Or do you take an action to reduce or stop the wheel spin as the gear travels to the stowed position?
Click to expand...
The Embraer 145 applies brake pressure automatically to the stop the wheel rotation before retraction.
 
positive rate, tap on breaks, gear handle up.
 
For my amphib or the turbo prop I tap the brakes, bigger stuff is normally automatic.
 
It would be interesting to have someone with a GoPro make a vid and see how long the wheels actualy spin on a small GA aircraft. My guess is it's not that long; not all that much rotating mass and some normal light friction from the brake pads probably have them stopped pretty quick.
 
I tap the brakes on takeoff before retracting but I don't think it really makes a difference. a) I leave the gear down longer than most just in case of a low level engine failure and b) the gear transit time for a Cardinal is over 20 seconds. By the time they are in the wells, they wouldn't be spinning anyway.
 
MD11Pilot said:
As an has been said. Depends upon the aircraft as to whether it is automatic or via scrub blocks. My MD11 is auto for the mains but scrubber for the nose. That is the way it is for most transport category aircraft. On the DC 8 it was specifically mentioned in the manual to NOT touch the brakes as all were scrubbers. There is a tremendous amount of inertia with these big tires and you can actually spin the tire on the rim and let all the nitrogen out if you apply brakes too quickly. Thirty plus years of transports and I have a very hard time pushing the brakes on my Bonanza.
Click to expand...
you don't need to push no stink'n brakes....the bearing drag will stop your wheels in a few seconds. ;)
 
eman1200 said:
Q2: I know a lot of peeps tap the brakes just prior to bringing the gear up. When I fly the lance I'm far more concerned with standing on the right rudder on takeoff than tapping the brakes.
Click to expand...
I (try to remember to) use the hand/parking brake lever in the Arrow. Doesn't do anything to the nose but it's a quick way to stop the mains without letting up on the right rudder.
 
next time one of you high winger goes flying....watch your wheels after lift off. I bet they stop rotating in seconds....not minutes.
 
Checkout_my_Six said:
next time one of you high winger goes flying....watch your wheels after lift off. I bet they stop rotating in seconds....not minutes.
Click to expand...

Not always. Sometimes I come across an airplane that hasn't had its bearings repacked in a long time, and they were left a bit loose to boot. They'll have no friction from either the grease, which is mostly gone, or from bearing preload, which should have been applied during wheel installation. No preload also means that the load is taken mostly by the bottom roller or two or three, not a good situation.
 
I took a ride on the Collings Foundation B-24 a few years ago. By paying a bit more for the ride I was on the flight deck during takeoff and was allowed to crawl through the tunnel into the nose shortly thereafter

The tunnel is pretty small, and I was surprised to see the nose wheel just a couple of feet away, still spinning merrily about a minute after takeoff.
 
I have a Johnson bar mooney so I tend to get the gear up pretty soon. I try to tap the brakes before retracting but to be honest I probably don't do it 50% of the time. Can't say I feel anything different or noticed any rubbing in the wheel wells.
 
I can't recall ever touching the brakes airborne in any airplane. The Arrow POH has no mention of it, nothing noted in 850 hours of operation.
 
You must log in or register to reply here.
Back
Top