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TUNED SILENCER
The O.S. Type T-6010 tuned silencer has been specially prepared for the MAX-140RX engine. It allows the engine to
develop high performance at lower engine r.p.m. (e.g.around 8,000r.p.m.) which enables the contest flyer to qualify for
noise reduction bonus points.
Here is an example of a combination with which maximum performance is obtainable at around 7,300-7,600r.p.m. You
may, of course, use other combinations, but it is recommended to refer to this combination as a starting point.
Propeller
Fuel
Exhaust Header Pipe
Tuned Silencer
Effective Pipe Setting
APC 16x14
Commercial good quality fuel
(10% nitromethane)
Actual length 240mm
(see sketch below)
O.S. Type T-6010
245mm (see sketch below)
Effective Header Pipe Setting ( 245mm)
Note :
Effective Header Pipe Setting means the distance from
the engine's exhaust flange to the entry to the tuned
silencer.
Header Pipe Length (245mm)
Center Line Length
5mm
Exhaust Header Pipe
Tuned Silencer
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Adjusting effective header pipe length
Use the silicone tube sleeve supplied with the O.S. T -
6010 and connect the silencer and exhaust header
pipe together so that the effective pipe length is as long
as possible.
Start the engine, open the throttle and measure the
maximum r.p.m. at which the engine runs steadily for a
lengthy period. Then shorten the header pipe setting by
10mm and measure r.p.m. again. Repeat this
procedure, checking r.p.m. each time, until no further
increase in speed is recorded.
For other combinations or conditions, set the effective pipe
length as follows.
(Important : Make sure that the engine is adequately
run-in before operating it at full throttle for lengthy
Note: Be sure to use the same fuel and propeller while
making these checks.
r.p.m.
High
Start with this setting.
r.p.m.
Low
Long
Effective Header Pipe Length
Short
From this measured data, you will find a range of
settings through which r.p.m. do not vary significantly.
Set the header pipe length at the beginning of this range
(See diagram bottom left ) and fly the model.
If the pipe length is too short, the needle-valve
adjustment range at maximum r.p.m will be narrow, and
r.p.m. will tend to vary too much in the air, especially
when revolutions build up as load decreases. Also,
power will tend to drop off excessively against increased
load in the air. To correct this, increase the header
pipe's effective length.
Note:
Engine r.p.m. recorded on the ground are different from
those achieved in flight; not only because of increased
propeller loading when the aircraft is stationary, but also
because the cooling airflow over the engine and tuned
silencer is reduced. Therefore, optimum header pipe
adjustment should be finally set only after actual flight
tests. The power absorption of individual propellers of the
same size (dia. and pitch), even from the same
manufacturer, may differ quite markedly. This can cause
r.p.m. to vary between 300 and 500 with standard
propellers and between 100 and 200 with high quality
propellers. Therefore, it may be necessary to readjust the
header pipe length when a new propeller is fitted. Be sure
to check the r.p.m. in addition to the balance and pitch of
the propeller, before using it for flight.
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If the pipe length is not set properly, the engine will not
only fail to develop its full performance but could also be
damaged through overheating.
If you wish to further reduce sound level, to meet extra
severe noise regulations, a larger(or coarser pitch)
propeller may be fitted to lower operating r.p.m. It will, of
course, be necessary to increase the header pipe length
accordingly.
Because noise generated by the engine and propeller
becomes louder as the r.p.m. increase, it is
environmentally desirable to run engines at reduced
r.p.m. for quieter operation, whenever possible.
Two adjustable controls are provided on the Type
70A carburetor.
CARBURETOR CONTROLS
The O.S. TYPE 70A carburetor has been designed
exclusively for use with the O.S. PD-06 fuel pump unit.
These two components, with appropriate plumbing
form the Pump System. O.S. Pump Systems offer the
twin advantages of increased power and the virtual
elimination of variation in fuel "head" at the
carburetor. The Type 70A carburetor has an extra large
throat, which improves breathing and increases
power. With normal suction fuel feed, or low-pressure
(exhaust) assisted fuel feed, such a large choke area
would be impracticable, but the special pump unit
ensures that fuel isdelivered to the carburetor at the
pressure required to maintain optimum mixture
strength, irrespective of fuel tank location or the
aircraft's attitude. These qualities are especially
valuablefor international class pattern aerobatic flying
and in models (including scale aircraft) where itmay be
difficult to locate the fuel tank close to the engine.
The Mixture Control Screw:
For adjusting the mixture strength at part-throttle and
idling speeds to obtain steady idling and smooth
acceleration.
The Throttle Stop Screw:
For setting the position where the carburetor rotor is
closed.
Throttle Stop Screw
Throttle Lever
Nipple
Mixture Control Screw
Mixture
Control Valve
Mixture
Control Valve Stopper
