Takeoff wheel spin
JbTex
As a casual observer of a/c, I've got a question.
When jet airliners take off, they seem to tuck their
landing gear away soon after liftoff. Is any retardation
applied to the spinning wheels before they're
lifted into their stowage position? Or can they
still be spinning after they're up?
Thx
Jim
John W. Alger
jb...@aol.com (JbTex) wrote:
>When jet airliners take off, they seem to tuck their
>landing gear away soon after liftoff. Is any retardation
>applied to the spinning wheels before they're
>lifted into their stowage position?
The answer is: BOTH. The main gear usually has the brakes
automatically applied to stop rotation. The nose gear is stopped by
friction pads in the whell well as it is retracted. Passengers can
sometimes feel the vibration from this if they are seated in the front
of the aircraft.
John
C. Marin Faure
> As a casual observer of a/c, I've got a question.
>
> When jet airliners take off, they seem to tuck their
> landing gear away soon after liftoff. Is any retardation
> applied to the spinning wheels before they're
> lifted into their stowage position? Or can they
> still be spinning after they're up?
I believe that the wheels come into contact with rub strips or blocks when
they settle into their retracted position, which stops the wheel
rotation. To my knowledge there is no automatic brake application as the
wheels are retracted. Even if there is, it wouldn't have any effect on
the nosewheels as they are not equipped with brakes. It may be that the
wheels are simply allowed to spin down on their own after retraction. The
next time I talk to someone at Boeing who I think would have the answer
I'll try to remember to ask.
When I used to fly an airplane with retractable gear (Rockwell 112), I
always tapped the brakes before retracting the gear, but this was more for
my own desire not to wear anything out. It was not part of the published
operating procedure of the plane, and the main gear wheel wells were
equipped with rubber blocks that brought the tires to a stop. I don't
remember if the nosewheel had a similar braking system or if it just spun
down on its own.
C. Marin Faure
author, Flying a Floatplane
Kim Hackett
In article <airliners...@ohare.Chicago.COM>, jb...@aol.com (JbTex) says:
>When jet airliners take off, they seem to tuck their
>landing gear away soon after liftoff. Is any retardation
>applied to the spinning wheels before they're
>lifted into their stowage position? Or can they
>still be spinning after they're up?
There is no retardation of the wheel that I know of.
I think it is ok for them to be spinning when they
enter the wheel well.
I suppose the pilot could touch the brakes after
lift off to stop the wheels from spinning.
Karl Swartz
>I suppose the pilot could touch the brakes after
>lift off to stop the wheels from spinning.
That's fine *IF* the plane and its computers allow this to have any
effect. Recall that at least the Fokker F100 disables the brakes
when when A/G sensors indicate the wheels are not on the ground.
This design combined with the failure of both sensors caused the
crew of a USAir F100 considerable consternation a few years ago when
then landed at Chicago O'Hare and found they had no way to stop!
--
Karl Swartz |Home k...@chicago.com
|Work k...@netapp.com
|WWW http://www.chicago.com/~kls/
Moderator of sci.aeronautics.airliners -- Unix/network work pays the bills
Jan Broe
JbTex <jb...@aol.com> wrote in article
<airliners...@ohare.Chicago.COM>...
> When jet airliners take off, they seem to tuck their
> landing gear away soon after liftoff. Is any retardation
> applied to the spinning wheels before they're
> lifted into their stowage position? Or can they
> still be spinning after they're up?
this was recently the subject of a very(!) long discussion on the Airline
mailing list and the answer was that almost everything is possible...
Some aircraft types are equipped with some kind of braking mechanism
(everything from rubber pads in the wheel well to a system activating the
brake upon gear retraction) and some are not...
Rgds
Jan Broe
CPH ATC
Stuart Law
JbTex <jb...@aol.com> wrote in article
<airliners...@ohare.Chicago.COM>...
> When jet airliners take off, they seem to tuck their
> landing gear away soon after liftoff. Is any retardation
> applied to the spinning wheels before they're
> lifted into their stowage position? Or can they
> still be spinning after they're up?
There is not any regulatory requirement for "spin-down", but it is a
feature of the "Anti-Skid" systems on all the transport airplanes I know
about. I just read of an incident where a pilot took off with Anti-Skid
OFF
and forgot to manually hit the brakes before retracting the gear and did
some substantial damage to the wheel well plumbing and systems.
--
Stuart Law stu...@slaw.com
Art Intemann
JbTex wrote:
> When jet airliners take off, they seem to tuck their
> landing gear away soon after liftoff. Is any retardation
> applied to the spinning wheels before they're
> lifted into their stowage position? Or can they
> still be spinning after they're up?
In the case of the main gear, braking (at a reduced pressure) is applied
when the shock struts extend. Most nosewheels are not equipped with
brakes, so some sort of snubbing (rub strip) causes the wheel to stop
spinning. Nose wheels generally retract fwd/aft, so that gyroscopic
precession is not a factor...
Just a driver,
Art
Greg Croydon
jb...@aol.com (JbTex) wrote:
>When jet airliners take off, they seem to tuck their
>landing gear away soon after liftoff. Is any retardation
>applied to the spinning wheels before they're
>lifted into their stowage position? Or can they
>still be spinning after they're up?
They usualy spin away, dissapating whatever heat may have built up. If
they are slightly imbalanced, the ensuing vibration from the nosewheel
can translate right into the flight deck for a few minutes.
bogie
In article <airliners...@ohare.Chicago.COM>, jb...@aol.com (JbTex) wrote:
> When jet airliners take off, they seem to tuck their
> landing gear away soon after liftoff. Is any retardation
> applied to the spinning wheels before they're
> lifted into their stowage position? Or can they
> still be spinning after they're up?
All the aircraft I work on use either mechanical or hydraulic brakes to
stop the spinning wheels when they're up in the wheel well. On the 727,
737 and MD88, the nose wheel is stoped by a mechanical brake made of an
asbestos brake pad mounted on the ceiling of the wheel well. The mains on
the 727 are stopped hydraulically by the application of the aircraft
brakes using a separate valve. The 737 mains use a similar system. You
can sometimes hear the nose wheels stopping after the gear come up if you
are sitting close enough up front.
Tom
Paul Kearney
: When jet airliners take off, they seem to tuck their
: landing gear away soon after liftoff. Is any retardation
: applied to the spinning wheels before they're
: lifted into their stowage position? Or can they
The main wheels are slowed down by the brakes during retraction.
The nose wheels are slowed down and stopped by the
pushing against "snubbers" in the roof of the nose-wheel-well.
regards to all
Dale Thompson
jb...@aol.com (JbTex) wrote:
>When jet airliners take off, they seem to tuck their
>landing gear away soon after liftoff. Is any retardation
>applied to the spinning wheels before they're
>lifted into their stowage position? Or can they
I can't speak for all aircraft.But as an aircraft technician on the DC9,
as the gear is raised a certain ammount of hydraulic pressure is applied
to the main landing gear brakes to stop their rotation.That is done through
the landing gear control valve sequence, not something the crew has to
do. That is designed to prevent any gyroscopic forces the tire/wheel
assy. may cause as the gear is retracted. The nose landing gear wheel well
has a row of bumpers that the tire hits and subsequently stops it's
rotation.
David K. Cornutt
In article <airliners...@ohare.Chicago.COM> JbTex, jb...@aol.com
writes:
>When jet airliners take off, they seem to tuck their
>landing gear away soon after liftoff. Is any retardation
>applied to the spinning wheels before they're
>lifted into their stowage position? Or can they
>still be spinning after they're up?
Funny you should mention it... Last week I took a trip to the
Lone Star Aviation Museum in Galveston (highly recommended),
and picked up a copy of a B-29 manual. (They have for sale
copies of manuals for a number of WWII-era aircraft.)
It cautions the pilot to apply brakes prior to retracting
the gear.
---
David K. Cornutt, Residentially Engineered, Huntsville, AL
email: cor...@hiwaay.net
I'm a rocket scientist. Don't tell me what TV I must see.
Robert Moore
Kim Hackett wrote:
> There is no retardation of the wheel that I know of.
> I think it is ok for them to be spinning when they
> enter the wheel well.
> I suppose the pilot could touch the brakes after
> lift off to stop the wheels from spinning.
Why in the world would someone with absolutely NO knowledge of the subject
at hand want to post BS such as this.
Having flown various Boeing and Lockheed jet transports for over 25 years,
they ALL had a auto-brake system on the main gear and rub strips on the
nose gear. Pilots were forbidden from using the regular brakes due to the
possibility of breaking the tire/wheel seal.
Sheeeesh!! Save us from the Internet.
Bob Moore
USN/PANAM (retired)
Eric Chevalier
>As a casual observer of a/c, I've got a question.
>
>When jet airliners take off, they seem to tuck their
>landing gear away soon after liftoff. Is any retardation
>applied to the spinning wheels before they're
>lifted into their stowage position? Or can they
>still be spinning after they're up?
Not quite "airliner" related, but ISTR reading an article many years ago
that wheel spin after take-off was a major problem for early C-5 cargo
transports. I believe the C-5 has four main landing gear assemblies,
each with 6 tires per assembly. Early in the flight test program, it
was found that after take-off, the gyroscopic force of so many spinning
wheels was preventing the retracting mechanism from working correctly.
So a fix was developed that would apppy brakes to the wheels before
initiating the retraction process.
========================================================================
et...@deltanet.com Eric Chevalier Compu$erve: 76010,2463
et...@netcom.com --------------------- Prodigy: GCXJ11A
http://users.deltanet.com/~etech
========================================================================
John M. Hunt
>this was recently the subject of a very(!) long discussion on the Airline
>mailing list and the answer was that almost everything is possible...
Can you please post instructions for subscribing to the Airline
mailing list?
-
-
John M. Hunt
john...@ipa.net
Kim Hackett
In article <airliners...@ohare.Chicago.COM>, Robert Moore
I do not believe that the original author of the newsgroup thread limited
his question of tire rotation to Boeing and Lockheed aircraft. For this
reason it seems appropriate to also consider other jet aircraft.
Today I asked other engineers here at Cessna how the Cessna Citation jet
aircraft are designed with regard to tire rotation after takeoff. I
learned the following:
1) Cessna does not use rub strips of any kind in the nose or main gear
wheel wells of any Citation jet aircraft.
2) The straight wing Citation jets; Model 500 (Citation 1), Model 525
(CitationJet), Model 550 (Citation 2), Model 560 (Citation 5), and Model
560XL (Citation Excel) do not have a method of stopping main tire rotation
using any kind of auto-braking system. For these aircraft, the tire
rotation is not restricted in any way during or after main gear
retraction.
3) The swept wing Citations; Model 650 (Citation 3, 6, and 7) and the
Model 750 (Citation X) incorporate an auto-brake pressure pulse for the
main gear tires only and is tied to the gear retract switch.
4) The nose gears on Citation jets do not have brakes, therefore a nose
wheel auto-brake system is impossible.
5) According to our engineering flight test pilots, they routinely tap the
brakes after liftoff to stop the main tire rotation. The tire/wheel seal
problem that you mentioned does not seem to be a problem on our jets.
6) Our Citation jet Models 550 and above are certified to Airworthiness
Standard FAR 25 for Transport Category Airplanes. This is the same FAA
certification basis as the Boeing and Lockheed aircraft that PanAm flew.
According to Cessna s FAA DER for Aircraft Loads, there is no FAR Part 25
requirement to eliminate tire rotation prior to gear retraction into the
wheel wells. In fact, FAR 25 paragraph 25.729 Retracting Mechanisms
specifies that the landing gear retracting mechanism, wheel well doors,
and supporting structure must be designed to withstand the gyroscopic
loads resulting from the wheels rotating at a peripheral speed equal to
1.3 times Vs occurring at airspeeds up to 1.6 times Vs1.
In conclusion, every straight wing Citation jet that is flying in the
world today has no method to stopping tire rotation after takeoff. In
addition, no Citation jets have a method of stopping nose tire rotation
after takeoff. My statements in the newsgroup are correct for Citation
jet aircraft and is consistent with engineering flight test practices at
Cessna.
I totally agree with your conviction that those who do not know what they
are talking about should not obtrude ideas as fact, nor criticize the
views of those who know what they are talking about.
Kim Hackett
Engineering Group Leader, Aerodynamic Loads
Cessna Aircraft Company
Wichita, Kansas