How do you find the limits of areas on a chart?

"flyncatfish" wrote

That's a good question. I think it's more like a truck brake.

Snippage

The Yak 52 has no parking brake, other than a latch on the stick handle
for keeping the brake handle compressed.

So if I understand correctly, you say if there is no air pressure there are no
brakes?

If that is the case, it is not like truck brakes.

Truck brakes have a very heavy spring that keeps the brakes applied on full
force, if there is no air. You can see why, so that if an air line or tank
ruptures going down the road, you just stop. Right now! I did it once from a
slow speed to see how good they grab. Very good is the answer! g You would
have major flat spots if you did it from any great speed!

How they work is by applying air to the back side of the air cylinder that
operates the brake. That pulls the shoes away from the drum, against the
"applying" action of the spring. When you want to stop, air is let into the
side of the cylinder on the opposite side of the piston as the first supply I
mentioned, and it pushes the shoe towards the drum, and at the same time, pushes
some of that first air back into the air tank. Really, what you are doing is
letting the spring apply the brake, by reducing the pressure differential from
one side of the piston to the other.

It sounds like you are worried if the air pressure drops too low from starting,
and that would not be a problem with truck brakes. Also, holding the brake
lever down for parking makes it sound like there is no applying spring, and air
on one side of the piston, only.
--
Jim in NC

Top-posted 'cause I'm lazy!

For a truck you want the brakes to apply if the air system fails.

For a plane, you want the brakes not applied if the air system fails.

In the truck you want the brakes to apply full on if the brakes system air
supply fails, it means you have to start the truck and wait for air pressure
to build before moving the truck, but it makes or safe driving when the
brake air fails on a big hill.

If the brakes were to be applied at full strength by a spring while you were
flying, then when you touch down, you will wind up on your nose or your
back, and you will have to call the insurance company.....

By having brakes that remain off if the air system fails, you can simply
land on a longer runway which allows for the non-functional brakes. Yet
another reason for having that emergency fuel in the tank, so you can divert
when the warning light comes on. Or you can have a lower speed taxi
accident, that as a pilot you should at least be able to kill the switches
before hitting the expensive whatever. Battle of Britain pilots were warned
that when a crash was going to happen, they were to crash into the softest,
least expensive thing.....

Although these air brakes don't make for a good long term parking brake,
chocks will hold a plane in one place, and even if air has leaked from the
tank, if the motor can be started and run until air is built up, the motor
can then be stopped and restarted later to supply enough air for the short
duration required if you alone have to remove the chocks while fuelling at
the bowser.

Hope this helps,
Pete


"Morgans" wrote in message
...

"flyncatfish" wrote

That's a good question. I think it's more like a truck brake.

Snippage

The Yak 52 has no parking brake, other than a latch on the stick handle
for keeping the brake handle compressed.

So if I understand correctly, you say if there is no air pressure there
are no brakes?

If that is the case, it is not like truck brakes.

Truck brakes have a very heavy spring that keeps the brakes applied on
full force, if there is no air. You can see why, so that if an air line
or tank ruptures going down the road, you just stop. Right now! I did it
once from a slow speed to see how good they grab. Very good is the
answer! g You would have major flat spots if you did it from any great
speed!

How they work is by applying air to the back side of the air cylinder that
operates the brake. That pulls the shoes away from the drum, against the
"applying" action of the spring. When you want to stop, air is let into
the side of the cylinder on the opposite side of the piston as the first
supply I mentioned, and it pushes the shoe towards the drum, and at the
same time, pushes some of that first air back into the air tank. Really,
what you are doing is letting the spring apply the brake, by reducing the
pressure differential from one side of the piston to the other.

It sounds like you are worried if the air pressure drops too low from
starting, and that would not be a problem with truck brakes. Also,
holding the brake lever down for parking makes it sound like there is no
applying spring, and air on one side of the piston, only.
--
Jim in NC

Morgans wrote:
"flyncatfish" wrote

That's a good question. I think it's more like a truck brake.

Snippage

The Yak 52 has no parking brake, other than a latch on the stick handle
for keeping the brake handle compressed.

So if I understand correctly, you say if there is no air pressure there are no
brakes?

If that is the case, it is not like truck brakes.

Truck brakes have a very heavy spring that keeps the brakes applied on full
force, if there is no air. You can see why, so that if an air line or tank
ruptures going down the road, you just stop. Right now! I did it once from a
slow speed to see how good they grab. Very good is the answer! g You would
have major flat spots if you did it from any great speed!

snip

Definately not like truck brakes than. Like BushyPete said having the
brakes engage if I lost air pressure would be a disaster. Probably
ground loop the plane or worse.

Greg in AL

"Jim Macklin" writes:

Boundaries: Beginning at 39° 12' 30"N lat., 86° 09'
50"W long.,

to 39° 07' 36"N lat., 86° 08' 00"W long.,
to 39° 07' 36"N lat., 85° 59' 30"W long.,
to 39° 00' 00"N lat., 85° 59' 30"W long.,
to 38° 57' 48"N lat., 86° 01' 29"W long.,
to 38° 57' 48"N lat., 86° 16' 06"W long.,
to 39° 06' 00"N lat., 86° 15' 00"W long.,
to the point of beginning.

All well and good, but rather awkward to review in the air (or even on
the ground).

--
Transpose mxsmanic and gmail to reach me by e-mail.