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Retractable Gear Technique

Posted: Wed Oct 07, 2015 12:29 am
by Four Bars
What's everybody's thoughts on tapping the brakes before selecting the gear up?
The thought behind this is that the heavy wheel and tyre possess considerable gyroscopic properties at this point and the gear attach points in the airframe must resist the twisting force of the spinning mass being moved through ninety degrees during retraction.
The opposite field of thought is that it is an unnatural force to put the wheels to, applying the brakes when there is no weight on them.
I only know that most larger aircraft route the retraction fluid through the wheel brake circuitry to at least some degree, ensuring the wheels stop rotating before they get up into the wheel wells...
It might be that the landing gear attach points are hellishly strong and absorbing this twisting force is never even noticed.

Re: Retractable Gear Technique

Posted: Wed Oct 07, 2015 12:52 am
by Slick Goodlin
I'm no engineer but the gyro loads on the landing gear during retraction can't come anywhere near the loads put upon it during a poorly done crosswind landing, right?
HuronPotentialConflict wrote: My question on this subject is: how soon can you put the gear up? if the wing has enough lift and you don't risk making ground contact again, is it okay to raise the gear?
I expect this to be a giant can of worms.  Put me down for "It depends on a lot of things."

Re: Retractable Gear Technique

Posted: Wed Oct 07, 2015 1:28 pm
by Liquid Charlie
I will side with the operating manual -- if it does not say to do it -- don't -- it's not required --

Re: Retractable Gear Technique

Posted: Wed Oct 07, 2015 3:40 pm
by Chuck Ellsworth
I will side with the operating manual -- if it does not say to do it -- don't -- it's not required --
Exactly.

Re: Retractable Gear Technique

Posted: Thu Oct 08, 2015 4:52 pm
by Strega
Depends on the a/c..

As my pie mentions, the skymaster and other cessna retracts are horribly draggy in transit.. so for example, a skymaster is flaps up at 200', gear up at 400' in normal ops..  If an engine goes kaput at 400', you can still manage to get the gear up without winding up in the trees...  In my 340... once positive rate is achieved, its gear up.


Re: Retractable Gear Technique

Posted: Fri Oct 09, 2015 2:15 am
by Chuck Ellsworth
Unless the POH has another method I rotate positive rate of climb and accelerate to desired climb speed as gear is selected up.