I rigged up a TamJets Smoke system to the Jet Luge this week, see the picts for the results... Lots o smoke. I got this to jack up the show a little on the dragstrip, even though I am running out of room to package anymore goodies in this design. For now I am using Super Dri for the fluid.

I do have one problem that I need help with. There is a fanned out residue pattern left on the asphalt after I use the smoke. It is kind of oily and I don't think they will be happy with anything slick at the start line. Any one have ideas on how to clean this up? Less fluid, different fluid, move the smoke tubes?
One more question. Does everyone have a delayed reaction turning on and off the pump? I was looking for an effect of quick pops of smoke (or flame) when I press the momentary switch. It seems to pump smoke for about 3 seconds after I let go of the switch. Any ideas on how to do this?

I will be running the Jet Luge at Maryland International Raceway for 3 days next weekend. It is the big IHRA Presidents Cup event and they are expecting near 20,000 spectators and Sunday will be televised on the Speed Channel... Who know what they will cut from the show, but I will be running in the show portion of the event with Bob Motz's Kenworth, and the Cool Bus
[link=http://www.mirdrag.com/schedule/event_listing/09-05/050925.htm]IHRA Presidents Cup[/link]

Any other ideas with the turbine to make a good show for the spectators would be appreciated.

Thanks
Bob

Hi Bob, for a good clean smoke shut-off you could add something like the fuel valve used for your engine. This should go after the smoke pump for best effect.

I have the ends of the tube well into the exhaust efflux to pre-heat the fluid for max vapourisation, this might help with your residue problem.

Smoke system we use will do morse.

.... --- .--. . / - .... .- - / .... . .-.. .--. ... / --..-- / .-. --- -...

Use the solenoid valve that Jetcat sells, works great, but costs around 70 bucks or so. If you find a less expensive one, let us know.

Using the Fuel Soleniod, do I leave the pump running or turn it on and off with the soleniod?

I suppose a nitrous solenoid or fuel injector from a car would also work, but the ycost the same.


bob

I just had a crazy ass idea... unfortunately one i dont have time to play with yet. Perhaps someone has already tried this already.

I was thinking.. since the smoke tubes sit in the high velocity air flow, couldn't you simply shape a notch cut or tab over an orfice hole about an inch before the nozzle end and the let the high velocity air passing the orfice create a negative pressure on the fluid draw side of the tube that would suck the fluid from the tank? As the fluid passed the orfice it would be pressurized to spray out the nozzle. Does this seem possible...? If this worked alls you would need is a soleniod to stop and start the flow. Perhaps I just invented a pumpless, self pressurized smoke system...? Ha... it may be worth playing with in the kitchen with some straws and a leaf blower..

My wife loves when I use the kitchen for experiments.


bob

Hmm It just hit me from high school... that would be a venturi pump.... wouldn't it?

[link=http://www.anver.com/images/components/generators/q-vp%20series/how_venturi_works.gif]venturi pump[/link]

So why wouldn't this work?


bob

I think that it would indeed work, but the flow rate would be too low for the good smoke we are used to.

But I could be wrong. Its worth a try!

bumping this back up to re- ask about the smoke soleniod.. When using a solenoid to turn the smoke on and off in quick bursts, do you leave the pump running or turn it on and off with the solenoid? If I left the pump running would I need a pressure regulator?? How are you doing this?

thanks in advance
bob

Bob, do you have on board propane?

If you do, run a check valve from the propane line to the vent on your smoke tank. Then use the jetcat valve to pulse smoke on and off. The pressure from your propane tank will keep constant pressure on your smoke tank against the valve, then when you crank the solenoid, you'll get the quick bursts you are looking for.

Bob, it seems to me that you can afford to put your tubes closer into the exaust. This will burn more of the fluid therefore leaving less of it on the ground. Its obvious that the residue being left on the ground is unburned fluid so there are only two solutions for that.

1) make sure to get all the fluid burned (it may be possible by simpy bending the tubes closer in to the exaust)
2) use less fluid (in return assuring that nothing is left unburned)

Just my opinion, maybe Tam can give you some better ideas once he gets back into town.


Dave

I turn both valve and pump on and off together, the valve is a standard brass pneutronics we are all familiar with.

Rob.

.-- .... .- - - .... . .... . .-.. .-.. -.-- --- ..- . - .-. . ... .- -.-- .. -. --.

Just drill a hole in the side of the engine and you will have ~20-30 psi... no pump required..

There may be a pressure tap somewhere in the front of the engine ready to go..

Eddie Weeks

Well I have the smoke system finally figured out with what I have on hand. Sean I will try the Pressurized method with the start gas when I get a soleniod.

I now have tons of smoke, perhaps to much, on demand. With an O'scope and some experimenting I discovered how Tamjet Smoke pump's speed controller want to be sweet talked. It is no wonder I had a huge delay and intermittant pump action. The speed controller on the pump wants to see low end pulses when you turn it on (approximately 1msec wide). If you turn it on with a much wider pulse or "fast" the controller ignores the pulses and does nothing. If you get the pump running and then switch the pulses off, the pump will run for about 3 seconds (must be waiting for the next pulse and times out). SO instead of setting my speed and turning the pulse on and off, I had to put a 5k resistor on a momentary swtich to my PIC's servo controller. Switch off (1msec pulse) Switch on (1.9msec pulse). This gives me real quick bursts of Smoke... as fast as I can hit the switch and long when I hold it....

To bad the skeeters are all ready dead around here....lol


thanks for all the suggestions...

bob

now to see how the crowd will like eating even more smoke at the drag strip..

In the full-scale world, we always use a solenoid valve on the same switch as the smoke pump. It's a little different situation than the open jet exhaust, but dribbling oil into a hot exhast pipe after engine shutdown can get a stack fire started. The venturi effect does tend to keep a small flow going after pump shut off. On my (full scale) Skybolt, I run a 50 PSI pump and 4 really small injection nozzles which extend 1/2 way into the exhaust pipes. I get really good smoke with very little residue on the plane. A lot of the guys using low pressure systems (basically an open AN fitting welded to the exhaust pipe) end up with the belly dripping oil after a ten minute flight. I'm pumping about 1 gallon/ minute.

What kind of speeds are you getting from the jetluge in 1/4 mile?

Tam Smoke on the Jet Luge in front of 20,000 spectators this past weekend @ the IHRA's Torco Fuels Presidents Cup Nationals. I was told my little smoke surprise brought the crowd to thier feet. I was also asked if I could dial the smoke down just a little... haha.

Pro Time Slip reads Car # Luge R/T .539 , 1/4mile 21.246 seconds, MPH 74.63

Pure Fun.
Next show in Rockingham, NC

thanks for all your help... now alls I need is little pops of fire.

bob

Looks good dude. Glad it's all working out for you.

If you hit the smoke, then throttle up alittle, you'll get a couple seconds of a flame show!!!

Hey Bob, try turning the smoke off half way down the run. It will have the visual effect of outrunning the smoke... sort of like going into afterburner.

Keep the tips for visual effects coming... even if they are not blessed by the AMA. As long as I do not upset or scare the IHRA, NHRA and NASCAR, I could probably do just about any stunt that I feel is not to dangerous to my life and limbs. We talked about doing a little marshmellow or weenie roast skit prior to taking my run...

Now as far as the flame pop effect... I assume the reason I cannot do this now is because the Super Dri Aircraft Smoke Oil I am using is not flammable enough. I have read where the desiel fuel / transmission fluid mix ignites for some people. Can you give me any idea on the mix ratio I should start to experiment with? I do want the flame to blow out to smoke as I thottle up. IS there any danger of the flame flashing back into the tubes?

And the last question. Does anyone have any idea what causes the evenly spaced bright rings in the exhaust of an afterburner? Are these shockwaves or harmonics??? This is probably the coolest thing I have ever seen coming out of a jet engine.
[link=http://www.ihra.com/gallery/album171/DSB_2278]Bob Motz- Afterburner Rings?[/link]

thanks
Fun With Turbines.
bob

Bob, I am sure the are aero guys that can explain it far better, but here is the way I remember it from my aero classes. They are Mach diamonds in the after burner's exhaust. They form along the shock wave lines, internal to the burner's exhaust, as the shock waves reflect back and forth, in the aft direction. Without a functioning after burner on your P-200, I don't think there is any way that you will be able to generate visible Mach diamonds, if that's what you are after.