Brakes on before gear retraction?
Join Date: Feb 2006
Location: Mel-burn
Posts: 4,875
Likes: 0
Received 0 Likes
on
0 Posts
"When you decelerate a spinning wheel in a split second like this, all that kinetic energy is absorbed by the hub, and can cause it to crack sooner than it otherwise would."
Are you for real?
Do you think there is more load on a wheel / hub when stopping in a nil weight condition versus the aircraft landing with say a couple of tonnes on it? It's no different to locking up the brakes.
That is just a wank sorry.
Are you for real?
Do you think there is more load on a wheel / hub when stopping in a nil weight condition versus the aircraft landing with say a couple of tonnes on it? It's no different to locking up the brakes.
That is just a wank sorry.
Join Date: Feb 2004
Location: NZ
Posts: 835
Likes: 0
Received 0 Likes
on
0 Posts
Tell me where on the previous page this point was stated? I can't find it. You may be confusing it with what someone said about tire creep, which, if you read my post, I disagree with.
I said nothing about load, I was talking about shock energy absorption. Like hitting something with a hammer compared to resting a mass on it that way's many times more than the hammer.
You won't get a wheel to stop spinning as quickly by locking up the brakes on the ground, yes the wheel will stop turning, but it won't happen anywhere near as quickly, and you won't (I hope) do it on every single flight. Similarly the wheel won't spin up anywhere near as quickly on even the most firm touchdown. Simple physics. If you don't agree, that's fine, it's only a theory and I invite you to disprove it.
I said nothing about load, I was talking about shock energy absorption. Like hitting something with a hammer compared to resting a mass on it that way's many times more than the hammer.
You won't get a wheel to stop spinning as quickly by locking up the brakes on the ground, yes the wheel will stop turning, but it won't happen anywhere near as quickly, and you won't (I hope) do it on every single flight. Similarly the wheel won't spin up anywhere near as quickly on even the most firm touchdown. Simple physics. If you don't agree, that's fine, it's only a theory and I invite you to disprove it.
With respect, Cloud Cutter, that is how religion works, not science. If you postulate a theory, the burden of proof is on you to prove, not on anyone else to disprove.
Disclaimer:
I take no responsibility for the results of any advice given out anonymously on the internet regarding the operation of an aircraft.
If in doubt, always consult the POH or your C.P. before operating an aircraft or a plane.
I take no responsibility for the results of any advice given out anonymously on the internet regarding the operation of an aircraft.
If in doubt, always consult the POH or your C.P. before operating an aircraft or a plane.
When you move on to bigger and better (oppinion only) things, you will be expected to operate the aircraft as per the aircraft flight ,manual and the company SOP's approved by CASA and generally based on information by the aircraft manufacturer.
Do yourselves a favour and begin that practice now and forget what your mate down the pub told you unless he can substatiate it with evidence from one of the above. i.e. aircraft POH/Flight manual or company SOP's. (company SOP's in light aircraft tend to be based on personal preference)
Boeing and Airbus go to a lot of trouble designing their undercarriage so that the brakes automatically activate and stop wheel rotation during retraction. The main reason for this is to prevent damage to the vital components in the wheel well from a delaminated tyre tread and to a lesser extent foreign objects such as mud and slush.
In the wheel well of aircraft types that I have flown there is hydraulic lines and reservoirs, fire extinguisher bottles, flight control cables and wiring looms. All would be damaged if a spinning delaminated tyre tread entered the wheel well.
I guess if there are any vital components in your wheel well it is a good idea to tap the brakes prior to retraction.
In the wheel well of aircraft types that I have flown there is hydraulic lines and reservoirs, fire extinguisher bottles, flight control cables and wiring looms. All would be damaged if a spinning delaminated tyre tread entered the wheel well.
I guess if there are any vital components in your wheel well it is a good idea to tap the brakes prior to retraction.
Boeing and Airbus go to a lot of trouble designing their undercarriage so that the brakes automatically activate and stop wheel rotation during retraction.
The main reason for this is to prevent damage to the vital components in the wheel well from a delaminated tire tread and to a lesser extent foreign objects such as mud and slush.
Just a thought!
Join Date: Mar 2000
Location: Still in Paradise
Age: 61
Posts: 861
Likes: 0
Received 0 Likes
on
0 Posts
I have no strong views either way; although I do apply brakes as part of the process before the gear comes up. In at least one turboprop I used to fly, failure to apply brakes before retraction resulted in a very distinctive burning rubber smell as the tyres rubbed on parts of the wheel well.
Join Date: Oct 2006
Location: ...
Posts: 341
Likes: 0
Received 0 Likes
on
0 Posts
very distinctive burning rubber smell as the tyres rubbed on parts of the wheel well.
If it burnt as a matter of course, maybe it was a brake pad in the wheel-well that caused the smell.
Maybe it was the designer's intent.
What type was it?
Join Date: May 2006
Location: Endor
Age: 83
Posts: 320
Likes: 0
Received 0 Likes
on
0 Posts
Wot Pig dog daid is correct.
Wot VH - XXX said is correct.
A simple calculation will show you that the your wheels are turning at around 2000 rpm after liftoff and perhaps slightly less on landing..
Forget about grass and mud sticking to the wheel at that speed - its gone in an instant. The tire of course will "grow" slightly at that RPM.
I am not sticking anything into my wheel wells thats turning at 2000 rpm, except the nose wheel, period. If the tire is on its last legs and deflating, if it took a stone fracture or something, if a bearing has decided to go at the wrong time, I do not want that much kinetic energy dissipating itself in my wheel well.
And having watched an engineer replace Arrow and similar cracked metalwork over time, I have great respect for the gyroscopic forces of retracting a spinning wheel as well.
Gentle tap after takeoff is always part of my routine on anything.
Wot VH - XXX said is correct.
A simple calculation will show you that the your wheels are turning at around 2000 rpm after liftoff and perhaps slightly less on landing..
Forget about grass and mud sticking to the wheel at that speed - its gone in an instant. The tire of course will "grow" slightly at that RPM.
I am not sticking anything into my wheel wells thats turning at 2000 rpm, except the nose wheel, period. If the tire is on its last legs and deflating, if it took a stone fracture or something, if a bearing has decided to go at the wrong time, I do not want that much kinetic energy dissipating itself in my wheel well.
And having watched an engineer replace Arrow and similar cracked metalwork over time, I have great respect for the gyroscopic forces of retracting a spinning wheel as well.
Gentle tap after takeoff is always part of my routine on anything.
There's almost no negatives to a gentle tap before retraction, and plenty of positive factors.
And as mentioned, the larger aeroplanes do it automatically for you anyway.
And as mentioned, the larger aeroplanes do it automatically for you anyway.
Join Date: Sep 2003
Location: Back too the hot bits again
Posts: 78
Likes: 0
Received 0 Likes
on
0 Posts
172 RG manual directs you to momentarily apply brakes before retraction,
They say that centrifugal force caused by the rapidly spinning wheel expands the dia of the tire, if there is an accumulation of mud or ice in the wheel well, the rotating wheel may rub as is it retracted into the wheel well.
I think this would apply to all retractables.
They say that centrifugal force caused by the rapidly spinning wheel expands the dia of the tire, if there is an accumulation of mud or ice in the wheel well, the rotating wheel may rub as is it retracted into the wheel well.
I think this would apply to all retractables.
In my experience in PN68s and Cessnas where you can see the wheel all of them seem to drag the brakes even slightly. When i've been a pax onboard a 172 i've watched the wheel and I reakon most of the time it stops spinning in less than 20 seconds, and even then it's not that quick. Esp in singles when your waiting until there is no runway left for retraction in RGs surely it's not that big of an issue. That being said it was taught and always did touch the brakes, but seriously have a watch of the wheel when your not flying, they do seem to slow up pretty quickly.
Join Date: May 2001
Location: S 40°12'07" E 175°22'52"
Posts: 76
Likes: 0
Received 0 Likes
on
0 Posts
It's very simple - read the Aircraft Flight Manual (AFM). If the AFM says apply the brakes before retracting the gear, apply the brakes!!!
If it doesn't. don't!!!!
Choice Bro'!
If it doesn't. don't!!!!
Choice Bro'!
short flights long nights
I agree with Frag. When I fly my Boeing I ask "What does Mr Boeing say?" when I fly my Cessna I ask "What does Mr Cessna say?". Just keep it simple
