JAGflyer
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Airplane Brakes

Fri Oct 13, 2006 4:55 am

To apply brakes on the plane while landing or taxiing (wheel brakes) I always was under the impression that you step on BOTH rudder pedals at once. Is that correct?
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2enginesonly
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RE: Airplane Brakes

Fri Oct 13, 2006 5:00 am

Basically, when you step on the left pedal, all brakes on the lh main landing gear or gears will pressurized and the right pedal the right brakes ( that's how you can steer without nosewheel steering ).
When you step on both pedals all brakes will get hydraulic power.

Arjan
 
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Starlionblue
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RE: Airplane Brakes

Fri Oct 13, 2006 5:03 am

Quoting JAGflyer (Thread starter):
To apply brakes on the plane while landing or taxiing (wheel brakes) I always was under the impression that you step on BOTH rudder pedals at once. Is that correct?

2enginesonly explains it well. It should also be remembered that brakes involve toe action. Ruddder/nosewheel steering involves heel action.

Differential braking is widely used. Some smaller aircraft, expecially tail draggers, don't have wheel steering at all so it is pretty much the only way of turning on the ground.
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KELPkid
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RE: Airplane Brakes

Fri Oct 13, 2006 5:03 am

Quoting JAGflyer (Thread starter):
To apply brakes on the plane while landing or taxiing (wheel brakes) I always was under the impression that you step on BOTH rudder pedals at once. Is that correct?

Not normally...you'd step on the toe portion of the rudder pedal on the side you want to apply the brakes on.

So, if you wanted to "slam on" the brakes in most aircraft, you would push down the top portion of both rudder pedals at the same time to the floor (and yes, I know different aircraft, especially light ones, use different methods for brake activation).

If I want to turn a Cessna rapidly, in as little space as possible (while taxiing of course  Wink ), I apply the toe brake on the side that I want to turn towards, and the aircraft will pivot around the main gear wheel on that side. Very useful in the run-up area.

Some light singles, like the Grumman Tiger or the Cirrus, don't have a steerable nosewheel, so you have to use differential braking to steer them while taxiing.
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JAGflyer
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RE: Airplane Brakes

Fri Oct 13, 2006 5:09 am

Most small aircraft I see have their rudders moving as they turn which indicates they are steering with the rudder pedals (nosewheel controled by rudder). How does the pedal work with sensing heel or toe pressure? How do you activate brakes on aircraft like C172 which have a "basic pedal" rudder.
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Starlionblue
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RE: Airplane Brakes

Fri Oct 13, 2006 5:15 am

Quoting JAGflyer (Reply 4):
Most small aircraft I see have their rudders moving as they turn which indicates they are steering with the rudder pedals (nosewheel controled by rudder). How does the pedal work with sensing heel or toe pressure? How do you activate brakes on aircraft like C172 which have a "basic pedal" rudder.

The rudder pedals are linked so if you press with your heel the entire pedal slides forward and the other pedal slides back in concert. However if you press with your toe, pivoting the pedal "forward", the pedal stays in place and brakes for that side are engaged.


I should add that slamming the brakes on some taildraggers moving at speed may well mean flipping the aircraft over on its back.
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KELPkid
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RE: Airplane Brakes

Fri Oct 13, 2006 5:17 am

Quoting JAGflyer (Reply 4):
How does the pedal work with sensing heel or toe pressure?

It is possible to apply both heel and toe pressure to each pedal at the same time. The toe portion is spring-loaded (to return to the normal position) and pushes down on a small slave cylinder through some mechanical stuff, which in turn activates the master cylinder for the brake(s) on that side. The bottom portion of the pedal is rigged to the rudder (and nosewheel) mechanism, so when pressed on one side, the opposite pedal moves "out", and you can feel the opposite pedal moving the other way with your feet.

Quoting JAGflyer (Reply 4):
How do you activate brakes on aircraft like C172 which have a "basic pedal" rudder.

Same as described in the previous posts...the C172's rudder pedals are pretty much conventional! Just push the toe portion (top) of the pedals.
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flymatt2bermud
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RE: Airplane Brakes

Fri Oct 13, 2006 5:17 am

Quoting JAGflyer (Reply 4):
How do you activate brakes on aircraft like C172 which have a "basic pedal" rudder.

Movement of the pedal will affect the rudder left and right. The upper toe portion is depressed to apply brakes on the cooresponding wheel brake. Left toe applied pressure will engage the left brake and vice versa on the right peddle/brake.
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2H4
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RE: Airplane Brakes

Fri Oct 13, 2006 6:23 am



Because I am who I am, I feel obligated to bring up a freakish exception to the aviation norm.

Here is the standard pedal arrangement, where the pedal is hinged in the middle and the pilot presses the upper half to activate the brake:






Here is an airplane equipped with heel brakes:

http://i9.tinypic.com/2uoopw6.jpg


In this case, the pilot controls the rudder/ground steering with the upper pedals. The brakes are controlled by the smaller, floor-mounted pedals.

This has been a 2H4 Tech/Ops obscure knowledge update. Thanks for reading.


Intentionally Left Blank
 
N231YE
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RE: Airplane Brakes

Fri Oct 13, 2006 6:29 am

I was drilled by my instructors to use only pedals and rudder to steer: no brakes. But sometimes I do "cheat" and use a little differential braking to make tight turns or to correct the airplane if I swayed to far off the taxiway centerline while taxiing.
 
Ralgha
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RE: Airplane Brakes

Fri Oct 13, 2006 7:32 am

Quoting N231YE (Reply 9):
I was drilled by my instructors to use only pedals and rudder to steer: no brakes.

Your instructors should have told you to use the brakes whenever necessary, turning or otherwise. The idea is to taxi the airplane in such a way that you minimize the need for brakes, but always use them if you need them. Most GA airplanes will not make a minimum radius turn without the use of brakes.
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EssentialPowr
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RE: Airplane Brakes

Fri Oct 13, 2006 7:41 am

Probably every standard in aviation has been reversed by some designer at one time or another...
 
KELPkid
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RE: Airplane Brakes

Fri Oct 13, 2006 7:49 am

Quoting EssentialPowr (Reply 11):
Probably every standard in aviation has been reversed by some designer at one time or another...

Indeed! Imagine if we stuck to the Wright Brothers control system, could you imagine laying on your stomach to fly and swaying your hips  Wink

I wonder how the whole counterintuitive elevator setup (pull back to move the nose up, push forward to bring the nose down) got started...wasn't the Curtiss Pusher the first aircraft with truly "conventional" controls?
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EssentialPowr
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RE: Airplane Brakes

Fri Oct 13, 2006 7:53 am

Quoting KELPkid (Reply 12):
Indeed! Imagine if we stuck to the Wright Brothers control system, could you imagine laying on your stomach to fly and swaying your hips

Wing warping may be coming back. NASA Dryden has an F18 that rolls via wing warping vice conventional ailerons. Saves weight and complexity...
 
KELPkid
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RE: Airplane Brakes

Fri Oct 13, 2006 7:59 am

Quoting EssentialPowr (Reply 13):
Wing warping may be coming back. NASA Dryden has an F18 that rolls via wing warping vice conventional ailerons. Saves weight and complexity...

Yeah, but I'm pretty sure you won't be laying in a hip cradle to control it  Wink
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N231YE
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RE: Airplane Brakes

Fri Oct 13, 2006 9:45 am

Quoting KELPkid (Reply 12):
I wonder how the whole counterintuitive elevator setup (pull back to move the nose up, push forward to bring the nose down) got started...wasn't the Curtiss Pusher the first aircraft with truly "conventional" controls?

As far as ailerons, Correct. What happened is that the Wrights had many patents, and were too greedy to allow Glenn Curtiss to use the wing warping design. So Curtiss came up with devices that would eventually become standard; ailerons.
 
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HAWK21M
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RE: Airplane Brakes

Fri Oct 13, 2006 1:57 pm

On B737.
Toe pressure for Brakes.Foot pressure Alternatively for steering on Ground.
regds
MEL
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DashTrash
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RE: Airplane Brakes

Fri Oct 13, 2006 8:56 pm

Quoting KELPkid (Reply 6):
It is possible to apply both heel and toe pressure to each pedal at the same time.

Yes it is. I usually have my feet off the floor a little and apply pressure to the top of the rudder pedal. I ease the pressure off the other pedal at the same time.
 
MrChips
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RE: Airplane Brakes

Sat Oct 14, 2006 4:52 am

Quoting 2H4 (Reply 8):

This has been a 2H4 Tech/Ops obscure knowledge update. Thanks for reading.

I'm gonna one-up you here - with finger brakes.

http://fileanchor.com/70393-r.jpg

On some aircraft, there are no brake pedals whatsoever - like on the Liberty XL-2 shown above. Rather, the brakes are actuated by levers between the seats. Interestingly, early Piper Cherokees had a similar system.
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2H4
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RE: Airplane Brakes

Sat Oct 14, 2006 7:33 am




Quoting MrChips (Reply 18):
I'm gonna one-up you here - with finger brakes.

Oooo...good one. On that note, I believe some Russian aircraft have brake levers mounted on the control stick...and IIRC, some incorporate a proportioning valve in foot pedals.

In other words, the pilot uses the hand lever on the stick to apply the total braking power, and the foot pedals to distribute that braking force to either the right or left pedal.



2H4


Intentionally Left Blank
 
KELPkid
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RE: Airplane Brakes

Sat Oct 14, 2006 7:57 am

Quoting 2H4 (Reply 19):
Oooo...good one. On that note, I believe some Russian aircraft have brake levers mounted on the control stick...and IIRC, some incorporate a proportioning valve in foot pedals.

Many ex-Soviet types also have pneumatic brakes...apparently hydraulic brakes have their limitations in Siberian winters  Wink
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MrChips
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RE: Airplane Brakes

Sat Oct 14, 2006 9:31 am

Quoting 2H4 (Reply 19):
Oooo...good one. On that note, I believe some Russian aircraft have brake levers mounted on the control stick...and IIRC, some incorporate a proportioning valve in foot pedals.

In other words, the pilot uses the hand lever on the stick to apply the total braking power, and the foot pedals to distribute that braking force to either the right or left pedal.

Forgot about that one; just about every Soviet-era fighter aircraft up to the MiG-29 and Su-27 had a braking system like that. Unfortunately, I'm fresh out of trivia regarding crazy braking systems...

Quoting KELPkid (Reply 20):
Many ex-Soviet types also have pneumatic brakes...apparently hydraulic brakes have their limitations in Siberian winters

...But I've got one on this. Due to poor cold-weather performance and poor quality control, petroleum-based hydraulic fluid was not used in most Soviet-era aircraft. Instead, they used 99% pure grain alcohol as hydraulic fluid. Needless to say, the mechanics would periodically drain off some of the "hydraulic fluid" for "chemical analysis", if you get what I'm saying... Big grin

[Edited 2006-10-14 02:31:38]
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ericsan777
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RE: Airplane Brakes

Sat Oct 14, 2006 11:07 am

What about on Seaplanes? Does that operate a different kind of HYDRAULIC brake system? LOL!
 
2H4
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RE: Airplane Brakes

Sat Oct 14, 2006 1:06 pm



Just a bit off-topic...but still related to controlling the aircraft on the ground:

I believe the Piaggio Avanti requires the pilot to physically move a selector to switch between tiller-based nosewheel steering and pedal-based nosewheel steering.

If I remember correctly, the pilot actually has to switch during the takeoff/landing roll. In other words, after landing, he or she must reach up and select the tiller-based steering mode before turning off onto the taxiway.

I thought that was rather odd.



2H4


Intentionally Left Blank
 
EssentialPowr
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RE: Airplane Brakes

Sun Oct 15, 2006 2:28 am

Quoting HAWK21M (Reply 16):
Toe pressure for Brakes.Foot pressure Alternatively for steering on Ground.
regds
MEL

Or the tiller for ground use...
 
EridanMan
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RE: Airplane Brakes

Mon Oct 16, 2006 2:58 pm

FWIW, My '67 Cherokee 140 has no toe brakes of any kind. There is just the Johnson Bar lever beside and beneath the throttle.

I thought this would be weird at first, and was about ready to put in the 15lbs of gear (and 10 hours of labor) to install the toe-brake system... my mechanic insisted, however, that I try the plane out for a few months, and if I still want toe brakes afterwards he'll do the install (he's a good guy, and apparrently the install is a pain in the ass).

Sure enough, I've got 15 hours on the plane now and I don't miss the toe brakes for an instant for a multitude of reasons (cheaper to maintain, lighter, and more comfortable).

Just to mix the game up a bit more Wink
 
KELPkid
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RE: Airplane Brakes

Mon Oct 16, 2006 3:11 pm

Quoting EridanMan (Reply 25):
FWIW, My '67 Cherokee 140 has no toe brakes of any kind. There is just the Johnson Bar lever beside and beneath the throttle.

Does it have the "toy" backseat  Wink I've heard that the back seat is practically unusable in Cherokee 140s...
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EridanMan
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RE: Airplane Brakes

Mon Oct 16, 2006 3:22 pm

Quoting KELPkid (Reply 26):

Does it have the "toy" backseat I've heard that the back seat is practically unusable in Cherokee 140s..

Do not dignify it by calling it a 'seat'... it is litterally nothing more than a pad and backrest sitting on the main-wing spar Wink

My Fiancee has ridden back there a couple times... granted she's 5'1, 100lbs, and a _very_ good sport... and she had to sit behind my instructor, as my 6'4 frame requires me to move the pilot seat all the way back, leaving a gaping 3 inches of legroom for the rear seat passenger.
 
futureuapilot
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RE: Airplane Brakes

Mon Oct 16, 2006 8:23 pm

The Rudder Pedals are connected by bungee cords to the main nose gear, so when you go to the runup area make sure you straighten your nose wheel. That way when you test your rudder, it does't pull those cords even tighter on one side then it already does.

At our airport I would find it dificult to taxi without using differential braking as well as the nose wheel steering..

-Sam
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Starlionblue
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RE: Airplane Brakes

Mon Oct 16, 2006 8:24 pm

Quoting EridanMan (Reply 27):
Do not dignify it by calling it a 'seat'... it is litterally nothing more than a pad and backrest sitting on the main-wing spar Wink

My Fiancee has ridden back there a couple times... granted she's 5'1, 100lbs, and a _very_ good sport... and she had to sit behind my instructor, as my 6'4 frame requires me to move the pilot seat all the way back, leaving a gaping 3 inches of legroom for the rear seat passenger

Sounds like my old Peugeot 206CC. Backseat was great for a couple of kids max age 6 or so.  Wink
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EridanMan
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RE: Airplane Brakes

Tue Oct 17, 2006 4:05 am

Quoting FutureUApilot (Reply 28):
At our airport I would find it dificult to taxi without using differential braking as well as the nose wheel steering..

The Bungee system was a Cessna Patent, Piper nosewheels are directly connected to the rudder... While this has its inconveniences, it does allow for more positive nosewheel position control when taxing.

Believe me... you don't miss the differential braking after your first 5 minutes on the ground.

-Scott
 
N231YE
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RE: Airplane Brakes

Tue Oct 17, 2006 5:04 am

Quoting EridanMan (Reply 30):
Believe me... you don't miss the differential braking after your first 5 minutes on the ground.

I totally agree, my single biggest annoyance with Cessna's.
 
KELPkid
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RE: Airplane Brakes

Tue Oct 17, 2006 5:46 am

Quoting N231YE (Reply 31):
Quoting EridanMan (Reply 30):
Believe me... you don't miss the differential braking after your first 5 minutes on the ground.

I totally agree, my single biggest annoyance with Cessna's

 Confused

I couldn't imagine whipping a plane around into it's tiedown by taxiing in straight or doing a 360 before takeoff (to look for traffic in the pattern) apart from Cessna's differential wheel brakes...
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futureuapilot
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RE: Airplane Brakes

Tue Oct 17, 2006 5:58 am

Quoting EridanMan (Reply 30):
Piper nosewheels are directly connected to the rudder

Ah, never thought about them Pipers... so when you check the rudder durring the runup are you physically turning the wheel on the pavement or do you do that while moving?

-Sam
The Pilot is the highest form of life on Earth!
 
EridanMan
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RE: Airplane Brakes

Tue Oct 17, 2006 7:32 am

Quoting KELPkid (Reply 32):
I couldn't imagine whipping a plane around into it's tiedown by taxiing in straight or doing a 360 before takeoff (to look for traffic in the pattern) apart from Cessna's differential wheel brakes...

Because the wheel is directly connected to the rudder, its pedal controlled 'steering range' is substantially greater than the cessna's... Just think about it, even the toe-brake equipped pipers wouldn't be able to 'spin on a wheel' with their direct connection unless the steering mechanism allowed the wheel to turn over that far, because unlike Cessna, there is _no_ way for the front gear to ever travel outside of the pedal control limits.

I have absolutely no problem taxing down a parking way, and making a hard turn to align my tail with the parking spot within the confines of the parking way... similarly, runup turns are a non-issue.

Now, in all fairness, this solution is more risky during crosswind landings - one of the things required in a piper check out is assuring that the pilot knows that the rudder MUST be centered before you put the nosewheel down on the ground... This is good practice in general, but in a Piper, its mandatory (toebrake equipped or otherwise).

But on the flips side, at least in a non-toebrake-equipped piper, I never need to worry about accidentally landing on a locked main (accidentally hitting the break while fighting a crosswind), so like everythign in aviation its a tradeoff...

Quoting FutureUApilot (Reply 33):
Ah, never thought about them Pipers... so when you check the rudder durring the runup are you physically turning the wheel on the pavement or do you do that while moving?

Attempting to turn the wheel while stationary is strongly advised against... a very slight forward motion is necessary.

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