Sky writing

"Viperdoc" wrote in message
A smoke system includes a tank, pump, and orifice in the exhaust manifold.
This system allows the smoke oil to get vaporized.

So is the oil is injected directly into the manifold through this orifice or
is there some more complicated, separate mechanism for heating up the oil?

--
Jim Fisher

While on a smaller scale, the local model shop rc guru said I should mount
the ten dollar extra cylinder cooling water jacket they sell for rc cars to
the fins of the head of my motor and their twenty dollar smoke kit which
was a bit of high temp tubing and a servo operated valve that squashed the
tubing to cut off flow. Pressure is supplied to the tank via a tapped
fitting to the motor crankcase that required removing the back plate
drilling and tapping a hole and inserting the fitting. This was to suit an
OS46, so it wasn't a large rc motor.

Heating the oil prior to injecting it gave more smoke. I do not know if this
would help on most airshow type high powered display aircraft, but would
expect some sort of preheat would give much more smoke on a smaller, lower
horsepower aircraft. This could be as simple as leaving the drum of oil out
in the sun (or on the combustion stove in Alaska) before filling your smoke
oil tank.

Hope this helps,
Peter


"Jim Fisher" wrote in message
...
"Viperdoc" wrote in message
A smoke system includes a tank, pump, and orifice in the exhaust
manifold.
This system allows the smoke oil to get vaporized.

So is the oil is injected directly into the manifold through this orifice
or
is there some more complicated, separate mechanism for heating up the oil?

--
Jim Fisher

"Bushy" wrote in message
...
While on a smaller scale, the local model shop rc guru said I should mount
the ten dollar extra cylinder cooling water jacket they sell for rc cars
to
the fins of the head of my motor and their twenty dollar smoke kit which
was a bit of high temp tubing and a servo operated valve that squashed the
tubing to cut off flow. Pressure is supplied to the tank via a tapped
fitting to the motor crankcase that required removing the back plate
drilling and tapping a hole and inserting the fitting. This was to suit an
OS46, so it wasn't a large rc motor.

Heating the oil prior to injecting it gave more smoke. I do not know if
this
would help on most airshow type high powered display aircraft, but would
expect some sort of preheat would give much more smoke on a smaller, lower
horsepower aircraft. This could be as simple as leaving the drum of oil
out
in the sun (or on the combustion stove in Alaska) before filling your
smoke
oil tank.

Hope this helps,
Peter

Many differences, between model smoke, and full size smoke, and even big
model smoke, and that mainly is the heat available.

Small model engines run on nitro methane, and the alcohol does not burn as
hot, giving low quality smoke. The larger gas engines for models have
plenty of heat. So do the big planes, even too much heat, while running
wide open. (hot)
--
Jim in NC


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So is the oil is injected directly into the manifold through this orifice or
is there some more complicated, separate mechanism for heating up the oil?

It is injected directly. You have to experiemnt a bit to find the sweet
spot....not too hot and not too cold.... where the oil will completely vaporize
and not burn. Plus the right size orifice is needed and this varies with each
airplane installation.
VL
(Mopar electric fuel pumps were great smoke oil pumps......cheap and usually
reliable)

The oil is pumped through a small orifice into the exhaust manifold near the
outlet. The exact location can make a big difference in the quality of
smoke.