MarkW

Brakes overheating on taxi

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Any ideas on how to prevent brakes overheating on taxi.  I was taxiing out for CTP today and was really concentracting on being "light" on the brakes as speed built during taxi....with throttles at min btw....F1 to make sure.  I still got the overhead warning by the time I reached the runway and 1 tire deflated.  Anyone else having this issue?

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Mark,

When you say you were being light on the brakes -- what technique were you using precisely?

The recommended technique is to allow the speed to build up to c. 20-30kt, then apply one, smooth brake application to bring the speed back down to about 10kt or so, then release the brakes and let the speed build up again before making a second application.

This is much easier on the brakes than "riding" them all the way down the taxiway.

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I was pressing on them about half way down to slow down to probably 15 knots then release.  Definitely not riding them.

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Mark,

I'm so glad you wrote about this... I've been trying to figure out what the heck I'm doing wrong or what settings to change.  I'm very experienced with airliners, and I don't believe it's me or the settings for the toe brakes... but anytime I taxi regardless of how easy I am I end up with the brakes overheating.  I've tried everything short of a 5 knot taxi and have really babied the brakes.

 

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The QOTSII brakes do not heat as easily as the 777, so when you have a problem and you are lightly using the brakes then check your null zone and calibration.  A small null zone on brakes can be helpful, and as Peter said don't assign axis in FSUIPC.

 

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Ok will check my calibration, currently done via FSUIPC. Interestingly Kyle recommends using FSUIPC processing of the axis in that other thread and I think that is what I have done.

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4 hours ago, MarkW said:

Ok will check my calibration, currently done via FSUIPC. Interestingly Kyle recommends using FSUIPC processing of the axis in that other thread and I think that is what I have done.

PMDG recommends that you don't assign axis in FSUIPC, but has no objections to using FSUIPC to calibrate or 'process' the axis.  Two different things.  I'm ignorant of using FSUIPC for any axis for any reason because using the P3D Controller UI works perfect for my controllers (Warthog HOTAS and Saitek Pedals).  I do use FSUIPC for translating buttons to keycommands and I've played with FS Controls use for things like elevator trim, but never something like a brake or throttle axis.

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I actually assign both my brakes in FSUIPC and I haven't had a Overheat issue yet.  Not to say that that isn't the cause of your issues...just saying I haven't had them.  Make sure you set a decent dead zone however to prevent dragging brakes and I would utilize the occasional brake action previously submitted.  Let the aircraft accelerate to about 20kts then lightly apply brakes to slow the aircraft to 10 or a bit less then let it gradually accelerate again.

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As a test, you might want to taxi down a long straight taxiway at a decent speed but without touching the brakes. Watch the gear synoptic to see whether the brakes get hot without you even touching them. That would point to a null zone issue or something of the sort.

 

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Good advice, will try all of this when I get some time.  I suspect its a null zone issue....I have similar problems with the 777

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