Aero braking vs...

J

JordanD

Here so I don’t get fined
Hopefully this doesn't start a whole new jc flap flare/gate IFR cancellation/roadhouse meme. Has anybody every figured out the effectiveness of aero braking after touchdown, vs. lowering the nose to get all the weight on the wheels to gain brake effectiveness? I hear a number of things, one of which was that holding the nose off puts all the weight on the mains where the brakes are and makes for more effective braking. Is that the whole reason for holding the nose off after touchdown or is that more to create more drag and slow the plane down? Just something I've been pondering...
 
I think it just kind of depends on the type of aircraft and the conditions you are landing in. Standing water and/or high crosswinds, I will plant it solidly and then try and go easy on the brakes until my groundspeed is under control. More normal conditions, I'll still get the nose gear on deck, and then use the stabs for aero braking to save the brakes. The latter being a little more aircraft specific.
 
kellwolf said:
Depends on the airplane, honestly. Are we talking 172 or something like a CRJ?
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Well in my case something like a 172, but I was wondering if the principles were basically the same. Then again in something like a CRJ you have the fancy spoilers and reversers to help you out.
 
JordanD said:
Well in my case something like a 172, but I was wondering if the principles were basically the same. Then again in something like a CRJ you have the fancy spoilers and reversers to help you out.
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Also, keep in mind that a swept wing doesn't generate as much drag as the wing on a 172. There's SOME aero braking, but most of your stopping power is coming from the brakes, spoilers and thrust reversers. If a CRJ had the same wing shape as a 172, then aerodynamic braking would essentially be the same. It'd also be crap at altitude when it came to speed.
 
JordanD said:
Hopefully this doesn't start a whole new jc flap flare/gate IFR cancellation/roadhouse meme. Has anybody every figured out the effectiveness of aero braking after touchdown, vs. lowering the nose to get all the weight on the wheels to gain brake effectiveness? I hear a number of things, one of which was that holding the nose off puts all the weight on the mains where the brakes are and makes for more effective braking. Is that the whole reason for holding the nose off after touchdown or is that more to create more drag and slow the plane down? Just something I've been pondering...
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Welllllll, in my experience, the reason for holding the nose off as long as possible is to reduce wear and tear on the nose wheel, primarily the shimmy damper. Regardless, in my experience, if you touch down at stall, then "over flare" once the mains are on the ground, I've found that that's only good for the first maybe 30% (WAG) of the landing roll. At some point, you've got to lower the nose and go heavy on the brakes, but if you do it too early you lose, and if you do it too late you lose. If I'm not doing a "max performance" landing, I aerobrake to be a little easier on the brakes. Be advised, retracting the flaps at this point will reduce aerobrake effectiveness. (No brainer, but I've watched people do it).
 
I aerobrake all the time. If there's no rush in getting off the runway I just hold the nose off and let it slow down without wearing the brakes. Again this is in fair weather. The F15s at the airport here ride on the mains for nearly 4000' before letting the nose come down. Now I'm no fighter pilot, but there's gotta be some effectiveness in aero braking if these guys are doing it.
 
I think its frowned upon at the airlines, judging from the firestorm I saw here about a UA pilot who aero braked 737 the whole way down the runway at ORD.
 
When I flew jets without T/Rs and landing at a 10k ft runway I would "aero brake" for about 4-5,000ft to save the brakes and nose wheel. Did it save the brakes and nose wheel? I have no idea but it couldn't hurt them and it allowed me to touchdown in the touchdown zone and keep the speed up for aircraft behind me.
Now we just try to be careful to ease the nosewheel down so it doesn't jar the bosses dip cup onto his iPhone, iPad, iMac, or iGirlfriend.
 
In the jets like the T-38 and F-15, it has more to do with energy dissipation than "saving" the brakes. Uncle Sam buys all my brakes, so I don't consider the cost in my decisionmaking process too much!

Aerobraking allows the jets to slow to a speed which will not build up too much heat in the brakes after leaving the runway.

Hot brakes are a bad thing, obviously.

So, aero braking works great in an aircraft where you don't have to consider the comfort of any pax.
 
As everybody has said, it depends on the aircraft.

One thing you should consider is that if you let yourself get too slow with that nose wheel up, you may get below a speed where the elevator is effective and, again depending on aircraft, you can drill the nose wheel into the runway.
 
As some have already mentioned a lot of factors need to be considered. I remember reading an article about aero breaking vs. conventional breaking a few years ago in B&CA. In essence aero breaking is fine for mil aircraft but not so for FAR25 aircraft. Main reason being the published landing distance. Have you ever thought about how test pilots get the published landing distance required in the flight manuals? Aero breaking is not part of that equation. Use the technique published in your aircraft flight manual.

I am sure most if not all pilots use 'aero breaking' at some point. Just a word of caution, have you ever thought about liability? What are you gonna tell the insurance if something goes wrong during your landing; that you used aero breaking to safe the brakes? Mind you the FDR will tell the 'story' anyway.

Landing overruns do happen. Don´t forget, one of the most useless things for a pilot is runway behind the airplane :D
 
///AMG said:
I think it just kind of depends on the type of aircraft and the conditions you are landing in. Standing water and/or high crosswinds, I will plant it solidly and then try and go easy on the brakes until my groundspeed is under control. .
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Wouldn't you just take a short-field arrestment, if available? Since the USN considers (rightfully) a runway arrestment to be a somewhat normal event, as opposed to the USAF who considers them an emergency that closes the runway for an hour or so.

Of course, a drag chute beats out aero braking, but the problem we had in the 117 with always using the chute was grease and gunk buildup on the little-used brakes. So when you did use the brakes during a non-chute landing they'd smoke, sometimes heavily, so much so that at bases other than homeplate, tower would assume you had a brake fire and would send you to the hot brake area to hold, even though there wasn't one.
 
MikeD said:
Wouldn't you just take a short-field arrestment, if available? Since the USN considers (rightfully) a runway arrestment to be a somewhat normal event, as opposed to the USAF who considers them an emergency that closes the runway for an hour or so.
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Absolutely, if things were out of limits for standing water or x-winds (or above my personal comfort level, which is pretty low right now :) ). It can still be pretty squirrely even below those numbers, so it's a Hornet technique for dealing with that......of course fuel/other considerations could dictate having to go into a civilian field, or an AF field that doesn't have the short field gear rigged as well
 
bizjetter said:
Have you ever thought about how test pilots get the published landing distance required in the flight manuals? Aero breaking is not part of that equation. Use the technique published in your aircraft flight manual.
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True, but thrust reversers aren't used in determining min landing distance in my aircraft. I still use them.
 
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