ACENTER offers the
complete set of the brake system elements for the light or ultralight
aircrafts.
The brake system
includes
1.
Master cylinder
2. Brake handle
3. Wheel cylinder
4. Parking valve
5. Dual control valve
6. Remote reservoir
7. Separate braking valve |
|
Elements of brake system are made of a high-strength aluminium alloy.
For connection of the high pressure piping the conic thread 1/8 "
is used.
Sealings are made
of oil resistant material with low friction factor ECOPUR.
All elements of the brake system are checked up under the pressure.
On the drawing the brake system's configuration variant is shown.
It is brake system
for the plane with dual control. Master cylinders are installed on the
control stick.
For the possibility
of braking for the right and left pilot either separately, or simultaneously
the dual control valve is used. The dual control valve is used in combination
with unblocking valve for preventing undesirable brake blocking.
For blocking brakes
on parking with started engine is used parking valve.
For increasing the
ground control efficiency of the plane is used the separate braking
valve. In case of using one master cylinder on the control stick the
separate braking valve allows to block both wheels at symmetric position
of the pedals or one wheel at the turned pedals.
Consultation
of a specialist
(Skirko Oleg,excerption
from article for the magazine " General Aviation")
As to the other
landing gear element, the brake system, It is worth noting that utilization
of elements specifically designed for certain technical conditions will
ensure controllable motion on the ground and ability to stop at the
desired point. At present a designer has a wide choice of brake systems,
but these are mainly manufactured in the Western countries. Either for
this reason or due to the too casual attitude to the brake system design
on light aircraft one can see either mechanical bike brakes or hydraulic
brakes with unreasonably small wheel cylinders and brake discs.
In the table below
you can see the pressure on the master cylinder piston necessary to
skid the wheel with different diameters of master cylinder pistons.
These calculations have been based on the parameters as follows: wheel
diameter 420 mm, aircraft weight 450 kg, master cylinder piston diameter
14 mm, brake disc diameter 200 mm.
Variant of one side
wheel cilinder:
|
Wheel
cylinder piston diameter, mm
|
Pressure
on the master cylinder piston, kg
|
Pressure
in the brake system, atm.
|
|
20,0
|
332.3
|
216
|
|
25,0
|
215.4
|
140
|
|
30,0
|
156.9
|
102
|
|
38,0
|
103
|
67
|
Variant of two side
wheel cilinder:
|
Wheel
cylinder piston diameter, mm
|
Necessary
pressure on the master cylinder piston, kg
|
Pressure
in the brake system, atm.
|
|
20,0
|
166.2
|
108
|
|
25,0
|
107.7
|
70
|
|
35,0
|
78.5
|
51
|
|
38,0
|
51.5
|
33.5
|
As we can see from
the table above, with smaller diameter of the working cylinder piston
and the brake disc it is almost impossible to put as much pressure on
the master cylinder as necessary to create the necessary pressure in
the brake system, which means that braking will not be efficient enough,
wheels will continue to turn. When designing a brake system it is desirable
to use: wheel cylinders with the maximum possible piston area; master
cylinder ensuring fluid consumption necessary to create working pressure;
brake discs of diameter as big as necessary to ensure the required braking
moment.
Following the example of the Western companies, we have designed and
organized production of a complete set of elements of a hydraulic brake
system for ultralight aircraft which ensure braking of aircraft with
up to 750 kg takeoff weight. These are master brake cylinders, wheel
brake cylinders, brake discs, fittings for various pipes.
Wheel cylinders can be of various types, as follows: single-piston cylinders
mounted outside the brake disc; single-piston cylinders mounted inside
the brake disc, double-piston wheel cylinders.
Master cylinder travel ensures consumption of fluid necessary for functioning
of double-piston wheel cylinders on two main wheels of an aircraft.
Designing the main cylinder and wheel cylinders we were trying to ensure
maximum hydraulic transmission ratio and therefore the maximum braking
power. Master cylinder piston has 14 mm diameter, wheel cylinder piston
has 38 mm diameter.
However, it is necessary to note that braking efficiency depends not
only on the parameters of the brake system but also on the mechanical
transmission ratio and configuration of the brake lever or footbrake,
brake hose rigidity, wheel diameter.
We have also developed and produce additional devices, like parking
valve which is used to ensure braking when the aircraft is parked with
the engine on. In case of an aircraft with dual control the braking
system can include the dual control valve which we also produce. This
valve allows every pilot to engage brakes independently. To maximize
control efficiency when taxiing the valve that ensures separate braking
of each wheel can be included into the braking system. This device (its
idea has been offered to us by our partner, AEROMECHANICS company) allows
to block either only one (left-hand or right-hand wheel, depending on
the position of the pedals) or both wheels when braking by means of
brake lever which is located on the aircraft control stick.
The main component parts of the brake system are made of aluminum alloy
D16T(2024), sealings are gasket sleeves and rings made of brake fluid-resistant
rubber.
The above is not anything new or unknown before.
