aircraft brakes were never designed for stopping aircraft.

On Sat, 19 Jul 2008 18:54:27 +0800, Stealth Pilot
wrote:


some interesting points came out of one guy's query re servicing some
old brake master cylinders.

gringomasloco commented regarding broken brake lines spraying brake
fluid over hot calipers and setting the wheels on fire. hmmmmm.

I am talking about light private aircraft here...

as I put it in the subject line aircraft brakes were never designed
for stopping aircraft. they were designed to hold aircraft.
now that may sound like semantic nonsense but it is true.

aircraft brakes were designed for use in holding the aircraft still
while the engine was started. after the taxy out and the engine has
warmed you do a run up check to make sure that the magneto circuits
are up to the bit of work that lies ahead for them. the brakes are
applied to hold the aircraft while the revs are bought up and each
maggy checked in turn.

Ahhh...I beg to differ here. First time I got someone qualified to
ride with me so I could get back in the air, they were astounded that
I could lock the brakes and acellerate.

(No, I didn't let it go very far as that's kinda hard on the tires,
but I assure you that with some planes you can take off with the
brakes locked *IF* the tires hold out. OTOH the landing and taxi are
going to be a bit bumpy:-))

BTW the brakes will hold it to do a runup IF you don't go past the RPM
listed for the runup of 2100 RPM at cycling the prop. Even the taxiway
*must* be clean and dry. It's already moving at 2400 and acellerting
when firewalled.

Those tires have a linear tread for squeezing water out and
maintaining direction. They aren't worth much for traction when it
comes to braking. Actually if you lock them up they start to
hydroplane on their own vaporized rubber.

It ain't the brakes, it's the tires and a lack of traction by those
tires. The brakes on the Deb will lock up the tires and that's as
much as you can get out of any brakes.


now brakes for commercial aircraft are different and they *are* used
for stopping, but the brakes on little lighties arent.
some people have yet to realise that.

Stealth Pilot
Roger (K8RI) ARRL Life Member
N833R (World's oldest Debonair)
www.rogerhalstead.com

now brakes for commercial aircraft are different and they *are* used
for stopping, but the brakes on little lighties arent.
some people have yet to realise that.

Stealth Pilot


What an utterly absurd statement! You may not need to use the brakes
to stop but that's what they're there for. On a long enough runway I
may not use the brakes at all but on a short runway, you better
believe the brakes will be needed to stop whether you're flying a 747
or a C-150. Everything is a compromise concerning weight and
capability on an aircraft; aircraft brakes on light aircraft may not
have the stopping power of power disc brakes on a dump truck but both
are designed for "stopping."

On Wed, 30 Jul 2008 16:14:26 -0700 (PDT), 150flivver
wrote:

now brakes for commercial aircraft are different and they *are* used
for stopping, but the brakes on little lighties arent.
some people have yet to realise that.

Stealth Pilot


What an utterly absurd statement! You may not need to use the brakes
to stop but that's what they're there for. On a long enough runway I
may not use the brakes at all but on a short runway, you better
believe the brakes will be needed to stop whether you're flying a 747
or a C-150. Everything is a compromise concerning weight and
capability on an aircraft; aircraft brakes on light aircraft may not
have the stopping power of power disc brakes on a dump truck but both
are designed for "stopping."

one day it is hoped that you will learn something of aircraft design
and good piloting skills.
untill then I suppose you'll just keep plugging away doing the best
you can as a poor pilot.

the brake pads on your aircraft are about 3/4" x 2" in size.
the aircraft weighs 1500lb.

....but why am I surprised. the average american doesnt even know how
to change a tyre.

Stealth Pilot

"Stealth Pilot" wrote in message
...
one day it is hoped that you will learn something of aircraft design
and good piloting skills.

And perhaps one day you will learn to read the responses to your posts,
several of which have proven you to be wrong about the purpose of aircraft
brakes. Did you ever bother to read any Cessna POH? (From Cessna 152 POH: (Step
6 of short field landing procedure) "6. Brakes-- APPLY HEAVILY.")

What are the FAA certification requirements regarding aircraft brakes? Do the
required certification tests involve actually stopping the aircraft?

Further, if light aircraft brakes are only there for holding the aircraft
against the engine (and perhaps for taxiing), why does every glider I have ever
flown have a brake installed on the main wheel?

Vaughn

On Jul 31, 7:00 am, Stealth Pilot
wrote:
On Wed, 30 Jul 2008 16:14:26 -0700 (PDT), 150flivver



wrote:
now brakes for commercial aircraft are different and they *are* used
for stopping, but the brakes on little lighties arent.
some people have yet to realise that.

Stealth Pilot

What an utterly absurd statement! You may not need to use the brakes
to stop but that's what they're there for. On a long enough runway I
may not use the brakes at all but on a short runway, you better
believe the brakes will be needed to stop whether you're flying a 747
or a C-150. Everything is a compromise concerning weight and
capability on an aircraft; aircraft brakes on light aircraft may not
have the stopping power of power disc brakes on a dump truck but both
are designed for "stopping."

one day it is hoped that you will learn something of aircraft design
and good piloting skills.
untill then I suppose you'll just keep plugging away doing the best
you can as a poor pilot.

the brake pads on your aircraft are about 3/4" x 2" in size.
the aircraft weighs 1500lb.

From the Cessna 172M POH, regarding forced landings:
6. Airspeed--65 to 75 MPH (flaps down)
7. Turn off master switch
8. Unlatch cabin doors prior to final approach
9. Land in a slightly tail-low attitude
10. Apply heavy braking while holding full-up elevator.

The Canadian Flight Training Manual, in the Landings section,
mentions braking during rollout several times.

In Canada we have something called the Canadian Runway Friction
Index (formerly the James Brake Index) and it gives approaching pilots
an idea of the runways surface conditions for things like steering and
braking during the landing rollout. I imagine other countries
(including Australia) have a similar scale.

So, it would seem that both the manufacturer and the people
who govern both flight training and international airports expect us
to use the brakes in the landing roll. Strange, huh?

We run six airplanes in flight training service. We find that
the brakes aren't hurt by normal use, even by heavy braking in a short-
field landing. It's the guys who taxi with too much power and hold the
taxi speed down using brake, and do that for 2000' on the taxiway.
That's when they get really hot and the metallic bits in the pads
begin to weld to the discs. Small raised steel burrs on the disc then
chew the pads up.
The pads and discs on a 150, say, are not unusually small for
the weight of the airplane when they're compared to the pads and discs
on the front of my compact car, which grosses three times as much as
the 150 and goes a lot faster on the ground than the 150 does. (The
rear brakes in most cars contribute maybe 20% of total braking and you
might not even miss them if they didn't work.) McCauley, and Cleveland
after them, design light aircraft bakes that are expected to stop
airplanes. If they didn't, someone else would and the manufacturers of
airplanes would buy those better brakes, believe me.

Dan

one day it is hoped that you will learn something of aircraft design
and good piloting skills.
untill then I suppose you'll just keep plugging away doing the best
you can as a poor pilot.

the brake pads on your aircraft are about 3/4" x 2" in size.
the aircraft weighs 1500lb.

...but why am I surprised. the average american doesnt even know how
to change a tyre.

Stealth Pilot

Gosh darn! I'm hurt that you call me a poor pilot because I
occasionally find it necessary to step on the brakes to stop my
aircraft. The placard against using the brakes for stopping must have
gone missing. The reverse thrust lever on my aircraft must have gone
missing along with that placard. How does a masterful pilot like
yourself decelerate on a short field landing before going off into the
trees? Perhaps you're used to landing on aircraft carriers with
arresting gear? Me thinks "Stealth Pilot" would be more aptly named
"Imaginary Pilot."

On Jul 31, 6:00*am, Stealth Pilot
wrote:
On Wed, 30 Jul 2008 16:14:26 -0700 (PDT), 150flivver





wrote:
now brakes for commercial aircraft are different and they *are* used
for stopping, but the brakes on little lighties arent.
some people have yet to realise that.

Stealth Pilot

What an utterly absurd statement! *You may not need to use the brakes
to stop but that's what they're there for. *On a long enough runway I
may not use the brakes at all but on a short runway, you better
believe the brakes will be needed to stop whether you're flying a 747
or a C-150. *Everything is a compromise concerning weight and
capability on an aircraft; aircraft brakes on light aircraft may not
have the stopping power of power disc brakes on a dump truck but both
are designed for "stopping."

one day it is hoped that you will learn something of aircraft design
and good piloting skills.
untill then I suppose you'll just keep plugging away doing the best
you can as a poor pilot.

the brake pads on your aircraft are about 3/4" x 2" in size.
the aircraft weighs 1500lb.

...but why am I surprised. the average american doesnt even know how
to change a tyre.

Stealth Pilot- Hide quoted text -

- Show quoted text -

You have recieved sane and reasoned responses to your 'theory'. They
have even provided some cites to back them up. Where is your evidence
that your 'theory' is correct? Untill you provide some respectable
source, I, and I am sure others, can one regard it as a 'cockamamie
theory'.

Harry K

"Stealth Pilot" wrote in message
...

as I put it in the subject line aircraft brakes were never designed
for stopping aircraft. they were designed to hold aircraft.

Where is that written?

Well, that "may" be true for certified aircraft. But with a homebuilt,
all bets are off. The builder is free to overpower his brake system
however he sees fit. And put large and powerful enough brakes on it to
provide plenty of energy absorbing power to stop his aircraft. Even
airliners have definite limits on their brakes. You take off heavy and
abort above 100 knots, and you are most certainly going to be in the
"melt zone". wherby the fuse plugs will melt and deflate the tires by
design. So your statement can't be a blanket statement about all
aircrat. Depends on the aircrafts weight at takeoff or landing. the
speed at which the brakes are applied to bring the aircraft to a stop.
It's all about engery, which is variable for each instance. So even
large aircraft have limits to their stopping power. They'll stop the
aircraft at just about any weight, but over a certain amount, and you
better not stand too close to it after landing.
Plus, way back when, old light aircraft had crap for brakes. Back when
Stinsons, Swifts, and other postwar aircraft were built, there were no
Cleveland brakes. With those, and clones of them, you can stop just
fine.




On Sat, 19 Jul 2008 18:54:27 +0800, Stealth Pilot
wrote:


some interesting points came out of one guy's query re servicing some
old brake master cylinders.

gringomasloco commented regarding broken brake lines spraying brake
fluid over hot calipers and setting the wheels on fire. hmmmmm.

I am talking about light private aircraft here...

as I put it in the subject line aircraft brakes were never designed
for stopping aircraft. they were designed to hold aircraft.
now that may sound like semantic nonsense but it is true.

aircraft brakes were designed for use in holding the aircraft still
while the engine was started. after the taxy out and the engine has
warmed you do a run up check to make sure that the magneto circuits
are up to the bit of work that lies ahead for them. the brakes are
applied to hold the aircraft while the revs are bought up and each
maggy checked in turn.

from a design aspect that is the end of the use of a light aircraft's
brakes until after landing and we wish to hold the aircraft still for
shutdown and disembarkation.

of course brakes are brakes and people will use them like they were
driving cars. light aircraft brakes were never designed for slowing an
aircraft when landing.
I know that they get used for that by students of bad piloting
technique but the design intent is a fact borne out by their
diminutive size.

I'll give one concrete example. The Stinson 108 is a huge aircraft, 4
seats in 1940's luxury, yet it only has brake pucks the same size as a
5.00x5 cleveland. in fact on the one Chris M-F ownes the brakes *are*
cleveland 5.00x5 calipers.

it is quite ok to be masters of the world and fly however you like.
you'll just wear out your aeroplanes faster.

just remember though that aircraft brakes are for holding the aircraft
not stopping it.

now brakes for commercial aircraft are different and they *are* used
for stopping, but the brakes on little lighties arent.
some people have yet to realise that.

Stealth Pilot

"Sliker" wrote in message
...
...
Plus, way back when, old light aircraft had crap for brakes. Back when
Stinsons, Swifts, and other postwar aircraft were built, there were no
Cleveland brakes. With those, and clones of them, you can stop just
fine.

Does a 1946 Cessna 120 qualify as a "postwar aircraft"? Brakes were good
enough for stopping hard enough to keep the tail in the air until you
stopped.

--
Geoff
The Sea Hawk at Wow Way d0t Com
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