ANTI-ICING ARRANGEMENTS FOR THE MI-1A HELICOPTER

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80T00246A011400340001-7
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 9
• Document Creation Date: December 22, 2016
• Document Release Date: August 10, 2009
• Sequence Number: 1
• Publication Date: October 4, 1960
• Content Type: REPORT

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ANTE-ICING ARRANGEMENT
FOR THE MHHIA HELICOPTER
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ANTI-ICING ARRANGEMENT
1. GENERAL INFORMATION
The anti-icing arrangement is designed to insure normal
flight of the helicopter in icing conditions. The anti-icing
prevents icing of the blades of the main as well as the tail
rotor and the forward windshield of the cockpit. Prevention of
the icing is based on the principle of creating a mixture of
super-cooled water droplets deposited from the atmosphere and
the alcohol supplied to the freezing surfaces. The freezing
'temperature of these mixtures and therefore the temperature
down to which the prevention of icing works, depends on the re-
lationship of the amount of water and alcohol in the formed mix-
ture. The less, the intensity of the deposit of super-cooled
water droplets from the atmosphere and the more the supply of
alcohol to the protected surface, the lower is the temperature
down to which the protection of the icing is provided. Con
versely, the higher the intensity of the deposit of the droplets
and the less supply of the alcohol, the higher is the temperature
at which the anti-icing ceases to operate.
In the helicopter MI-IA the amount of the supply of alcohol
is such that at the higher output of the pump and maximum de-
posit of the droplets possible at the given temperature, the
prevention of icing occurs down to -20 C.
Pure alcohol of 95 to 96% concentration is supplied to the
surfaces to be protected against icing.
The supply of alcohol is started at the first sign of icing
on the windshield or on other protruding parts of the helicopter,
also when abnormalities of the helicopter (shaking of the control
stick, vibration of the helicopter) occur.
In order to insure the supply of the alcohol to the surfaces
of the main and tail rotor blades and to the windshield the heli-
copter has two independent systems.
2. ALCOHOL SUPPLY SYSTEM TO THE SURFACES
OF THE MAIN AND TAIL ROTOR BLADES
The alcohol supplied to the blades of the main and tail ro-
tors is contained in the tank (#18) Figure 1, attached by means
of bands and brackets in the tai-l- -boom -on---?.the =1-ef-t ?s-i-de.
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The welded tank containing 28 liters is made out of AM$4A
material, is basically cylindrical and has two internal open par-
titions. In the upper part of the tank there is a filler (#17)
containing a filter, a cap and a dipstick and the connection .
(#14) which connects the tank to the atmosphere via the draining
pipe (#21) and fitting (#15) which connects the drain pipe of
the pump to the tank.
In the lower part of the tank are located fitting (#16) for
the connection of the tank to the intake line of the pump and
fitting (#19) for the drainage of alcohol from the tank.
Under the tank (#18) on and aluminum alloy bracket attached
at location (#6) of the tail boom is the alcohol pump (#20)
Type C4H-l, which supplies alcohol from the tank to the blade
surfaces of the main and tail rotors.
The centrifugal pump CqH-l consists of a D.C. electric
motor MBf-]A, attached to the pump body, an impellor attached to
the shaft of the electric motor, the pump housing, and the intake
and outlet fittings.
In the body of the pump there is a pressure seal for the
prevention of leakage of alcohol. The motor also has a pressure
seal. Between the two pressure seals a small cavity is created
in the pump body which is connected to the atmosphere with a
drain tube. Alcohol which leaks through the pressure-seal in
the pump body is drained outside and cannot enter the motor.
In the upper part of the pump cover there is a fitting with
an orifice to vent the alcohol vapors and air from the highest
point of the pump into the upper part of the tank. The intake
in the center of the cover is connected by the main line to the
tank. The alcohol flows from the pump through the output fitting
which includes the check valve.
The check valve is required to prevent the flow of alcohol
from the main line due to the pressure column of the fluid and
reduced pressure of the air near the output orifice when the
pump is not, operating, and also in order to prevent the return
of alcohol from the main into the tank when the pumji is tempor-
arily shut off.
The electric motor MBl-lA has mixed windings for the excita-
tion and a resistor to vary the shunt field. The motor has two
working regimes "normal" and "high". At the "normal" work
regime when the resistor is disconnected from the shunt winding,
the motor develops 8000 to 8300 rpm's. The "normal" regime of
the motor provides protection against icing down to -10 C.
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In the "high" regime, the motor develops up to 11 000 rpm.
This "high" regime insures ice protection down to -206 C. At
temperatures of -100 C and lower it is always mandatory to use
"high" regime.
The outlet of the pump is connected through the check valve
by tubing of 12 X 10 diameter made from AMr to the filter CC1-1
(#13), combined with the regulating valve (#11) on the left side
of the pylon.
The regulating valve regulates the amount
of
alcohol.
It
consists of body(#33), metering valve (#31),
three output fittings.
seal
(#32),
and
The metering valve, after it is adjusted, is locked by a
check nut and sealed. There is a hydraulic line to connect the
pressure switch to one of the output fittings.
The pressure switch U,-16A serves to warn the pilot when
there is no longer any alcohol in the tank and for automatic shut-
down of the pump CLJH-1. The pressure switch has diaphragm op-
erated contacts. The diaphragm is spring loaded such that the
switch closes at pressures on the diaphragm of .25 + .02 Kilograms
per square centimeter (3.8 + .29 psi). The action of the switch
is as follows: when the pump push buttom is depressed, the con-
tactor 25A is energized and the electric motor is turned on to-
gether with a green light located in the cockpit. When the pump
is operating the pressure of alcohol on the diaphragm connects
the contacts of the switch CA-16A. The contacts of the switch
short the push button contacts. Therefore with presence of the
alcohol pressure the contactor K-25A is maintained in the switched-
on condition by means of the contacts of the pressure switch
CA-16A with the push but torn released.
If all alcohol in the tank is consumed the pressure of the
alcohol drops, the contacts of the switch are opened switching.
off the contactor K-25A and also the pump CI4H-1 with the green
light. The main supply line of the alcohol to the main and tail
rotors is connected to the two other fittings of the regulating
valve.
The main line of the alcohol supply to the blades of the
main rotor is connected to the fitting (#29) attached to the
stationary ring of the swash plate, from which the alcohol is
conducted via tubing 6 x 4 to the jet (#30). The slinger of the
main rotor (#10) is attached to the rotating ring of the swash
plate. It consists of two discs welded together on their peri-
phery. and forming a (slinger) ring open on the inner diameter.
To the outside of the slinger (periphery) are welded nine fittings
which are connected to nine hoses, three for each rotor (connect-
ing the slinger to the blades of the main rotor). The hoses are
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attached by means of clamps on special brackets to the hinge
pins. The slinger of the main rotor provides uniform distribu-
tion of alcohol to the blades as well as to the individual sec-
tions of each blade. The alcohol of the anti-icing system is
forced by the pump CqH-1 through the filter C*-l and regulating
valve to the jet through which it reaches the internal space of
the slinger. With a uniform rotation of the slinger and uniform
location of the output fittings on the slinger, the amount of
alcohol which reaches eachsection of the blade is uniform.
The alcohol flows under the influence of the centrifugal
force from the slinger to the blade fittings, from where through
internal passages it reaches the three sections of each blade.
At the start of each section, the alcohol enters a,channel
formed by the nose cap. The alcohol passes along the whole
section and is forced by the air flow through orifices in the
nose cap onto the nose of tie blade, thus washing it. For the
purpose of a more uniform washing of the blade, the alcohol is
conducted separately to the three sections. The main line of the
alcohol supply on,rthe tail rotor is made of copper tubing 4 x 3.
It is connected to the jet (#28) for the slinger on the tail
rotor.
The jet is attached to the tail rotor transmission. Between
the flanges of the main line and the jet there is a washer con-
taining a regulating needle (#26) which regulates the amount of
alcohol to the tail rotor.
The slinger of the tail rotor (#27) provides uniform dis-
tribution of alcohol to the blades. It consists of a ring of
a half circular profile with the open part towards the center
of rotation.. Three fittings are welded to the outside, uniform-
ly arranged, to which flexible hoses are attached conducting
the alcohol to the blades of the tail rotor. The slinger is at-
tached by means of welded lugs to the flange-of the hub of the
tail rotor. When the pump is on the alcohol is conducted via
main line to the jet of the tail rotor and enters the internal
space of the slinger and is centrifugally directed through flex-
ible hoses to the blades of the tail rotor.
On each blade of the tail rotor, are stainless steel covers.
Between the cover and the nose of the blade, a small channel is
formed for the passage of alcohol along the whole length of .the
blade. The over is. attached to the blade at the root with screws
and-further to: the very tip of the blade by mea' s of copper rivets.
The rivet heads are soldered. Due to the centrifugal force the
alcohol flows in the channel between the cover and the nose and
out through the holes in the cover onto the surface of the blade.
Three tubes - (#22), (#23) and (#24) - are provided to drain the
system. There is another drain tube (#25) in the main line
supplying alcohol to the tail rotor.
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3. THE SYSTEM FOR SUPPLYING ALCOHOL
TO THE WINDSHIELD
The system for supplying alcohol to the windshield (see
Figure #l) consists of a little alcohol tank (#9), a metering
valve (#8), lines and windshield wiper AC-2. .The alcohol tank
of 2.5:liters capacity is welded from AMIJA, and has a filler
containing a filter. The filler plug has an atmospheric vent.
The alcohol tank is attached on padded bands and under the front
pylon so that the filler plug is protrudin through the outer
surface of the pylon. The metering valve (#8) consists of a
body (#1), a metering valve with wheel (#2), a spring (#5) and
a seal.
The metering valve is attached to the upper edge of the
windshield frame. The line from the tank consists of a copper
tubing 3 x 2 connecting to a rubber tube glued to the blade.of
the windshield wiper(#6). The rubber tube. has orifices for
supplying alcohol to the windshield. The end of this tube is
plugged.
Windshield wiper AC-2 consists of electric motor (#3) with
a flexible shaft (#4). A mechanism (#7) transforms the rota-
tion into oscillating motion of the blade (#6).
The intensity of icing of the windshield is determined
visually.and the supply of alcohol is adjusted accordingly by
means of the metering valve.
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1. Body of ;the metering valve.
2. Metering valve with wheel.
3. Electric motor of the windshield wiper AC-2
4. Flexible shpft
5. Spring of the metering valve.
6. Blade of the windshield, wiper AC-2
7 Oscillating mechanism AC-2
8. Metering valve
9. Alcohol tank
10. Slinger of the main rotor
11. Regulating valve
12. Pressure switch
13. Filter,
.
14. )
15-- ) Fittings of the tank
16, )
19. ) .
17. Filler of the tank .
18. Tank
20. Alcohol pump, .
2. Drain tube of the tank
22. Drain.from the, pump
23..Drain from the main line
24:
Drain from the tank
25?
Drain from the main line
26.
Needle valve
27
Slinger of the 'ta i l rotor
28.
Jet of the.slinger.of the tail rotor
29.
Fittings
30.
Jet of the stinger of the main
rotor
31.
Regulating needle (valve)
32.
Seal of the regulating valve
33.
Body of the regulating valve.
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