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smoke oil



 
 
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  #11  
Old March 5th 04, 06:00 PM
Andrew Boyd
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"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
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  #13  
Old March 5th 04, 06:15 PM
nametab
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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



  #14  
Old March 5th 04, 06:21 PM
Wright1902Glider
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What type of volume would you expect to use on a small piston engine.. say an
80 CID Harley Evo v-twin?

Harry
  #15  
Old March 6th 04, 04:42 AM
Wingedhoof
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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.
  #17  
Old March 16th 04, 06:02 PM
Wright1902Glider
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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
  #18  
Old March 18th 04, 02:40 PM
Bushy
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- 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


  #19  
Old March 25th 04, 05:34 PM
Wright1902Glider
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Peter,

Gives me a few ideas. Thanks for your suggestion.

Harry
 




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