smoke oil

"nametab" wrote:

How much volume are you trying to push through there. We are up to almost
1gal/minute and getting fair smoke, but with the rotor downwash, it defuses

The volumn of smoke oil you can pump through depends upon the
volume of your exhaust gas. A bigger engine, or running at a
higher RPM (or both) will usefully allow a higher smoke oil
volume.

For a big piston engine (eg 540 cubic inches) 1 gal/min should
give very good smoke, with the right smoke oil. Check the
flashpoint of your oil - betcha it's up around 400F. You'll
get better smoke with a (CoC) flashpoint of 250F.

As far as dealing with rotor downwash, you're on your own! I
don't know nothin' 'bout fling wing :-)

--
ATP http://www.pittspecials.com/images/oz_down.jpg

(Gus Rasch) wrote:

I contacted NOCO about the oil you mentioned in your article and they
stated that they no longer produce that oil.

Someone emailed me and said that NOCO wanted a minimum
10 barrel order, which I intend to place in the near
future - I've got three thirsty S-2B's to keep smoking
and we can go through a barrel in one weekend - that's
only 3 flights :-)

--
ATP http://www.pittspecials.com/images/da2.jpg

It's a turbine, so can't change the RPM! The measured temperature at the
injection point is at least 450C and up to 600C, so I wonder what the flash
point difference between 250f and 400F would have. Will check the flash
point of the stuff I'm using. I'm also using quite a lot of diesel to make
it flow; about 1/3. It does make cool smoke when the flow goes through the
Fenestron... but in a hover it just gets defused by the rotor wash.

"Andrew Boyd" wrote in message
m...
"nametab" wrote:

How much volume are you trying to push through there. We are up to
almost
1gal/minute and getting fair smoke, but with the rotor downwash, it
defuses

The volumn of smoke oil you can pump through depends upon the
volume of your exhaust gas. A bigger engine, or running at a
higher RPM (or both) will usefully allow a higher smoke oil
volume.

For a big piston engine (eg 540 cubic inches) 1 gal/min should
give very good smoke, with the right smoke oil. Check the
flashpoint of your oil - betcha it's up around 400F. You'll
get better smoke with a (CoC) flashpoint of 250F.

As far as dealing with rotor downwash, you're on your own! I
don't know nothin' 'bout fling wing :-)

--
ATP http://www.pittspecials.com/images/oz_down.jpg

What type of volume would you expect to use on a small piston engine.. say an
80 CID Harley Evo v-twin?

Harry

It's a turbine, so can't change the RPM! The measured temperature at the
injection point is at least 450C and up to 600C...

Temperature matters. For instance, the USAF and USN jet teams inject at the
aftmost plane of the exhaust nozzle. That's fine as long as the throttles are
at MIL or less, but if they go into burner, the smoke disappears.

BTW, the Thunderbirds use about one drum of smoke oil (1010) per jet per
half-hour performance.

wrote:

What type of volume would you expect to use on a small piston engine
say an 80 CID Harley Evo v-twin?

Let's make some horrific assumptions about RPM
and volumetric efficiency. We know that 1 gallon
per minute works for 540 cubic inches. Therefore,
for a 80 cubic inch engine under the same conditions:

(80 cubes / 540 cubes) x 1 gal/min = 0.15 gal/min

Note that we run our direct-drive aircraft engines
at less than 3000 rpm, otherwise our prop tips go
supersonic, and that's a whole different world.

I suspect your RPM might be a bit higher than ours,
lets say 6,000 rpm or twice ours, so that would double
(maybe) your exhaust gas flow, therefore you might try
0.30 gal/min flow, which is a bit aggressive, but I
suspect might work quite well.

When running smoke, you need to have the throttle
open, making power and RPM. Smoke doesn't work
well at low power settings - no exhaust gas flow,
and the stacks are cold.

Hope this helps - I can guarantee it's worth what you
paid me for it! :-)

--
aboyd

Thanks for your help. My target RPM on the v-twin is going to be in the 2,500
- 3,500 range. That's probably as hot as I could turn it and not overheat the
motor.

My intention for the smoke system is to produce a 50' dia. cloud of dense smoke
while still on the ground at the end of the runway, ramp, etc. Then slowly
emerge from said cloud in dramatic fashion. Don't know if that'll work, but I
think its worth a try.

Thanks again,
Harry

- 3,500 range. That's probably as hot as I could turn it and not overheat
the
motor.


My local model outlet where I have been looking at a smoke system offered a
water cooling wrap around pipe for the head from a motorised glowplug RC car
to use a a smoke preheater so the oil mix would flow from the tank through
the valve to the preheater and then to the exhaust. Preheating the oil mix
was said to dramatically increase the smoke from cooler exhausts.

The model smoke system, a length of "rubber" pipe and a double on/off valve
sold for about $20 and the preheater, actually a cooler sold for about $10.
The double valve supplied pressure from the crankcase to the tank via one
line and the other was the outlet from the tank. Also included was a fitting
thatwas to bve tapped into the crankcase to obtain air pressure.

This could be a simple length of metal tubing that was wound around the
aircooled head to provide a run of heat to the oil before it is introduced
to the exhaust.

Hope this helps,
Peter

Peter,

Gives me a few ideas. Thanks for your suggestion.

Harry