Smoke and tuned pipes?

[chrisbchips]

Hey guys,

I have just recently gotten round to installing smoke in my 3m Comp-ARF 260 (Powered by DA150 BTW) and was wondering who has used smoke with tuned pipes before? I am running the BMB tuned pipes, and was just wondering where people are putting the fluid injectors in the headers (ie, right near the manifold, the header curve, or nearer the neck of the pipe)? The style of injector, whether its been closed off to limit the flow of the fluid? And whether any pre-heating is neccessary (wrapping coils of copper tubing around the header before being injected)?

Another FYI, I am using crankcase pressure for the smoke, no pumps.

Thanks for any help you can offer gents!!

[Mr Boombastic]

The smoke injector needs to slope slightly back away from exhaust opening so that the fluid is sucked out of the injector. A type of spray bar setup is good if you can find someone to do it. You can adjust flow rate via radio mixing with the servo to your shut off valve. You will need a one-way check valve after the crankcase pickup line, this needs to be good due to the fast pressure pulses in the crankcase.
Don't forget that your motor will suck back some exhaust that will have your fluid in it, which it won't like much, so have your smoke mostly on above 50% throttle. Futaba web site has radio mixing information in FAQ.
Watch out for the EPA (Enviromental Pollution Authority) guys.
Good Luck.

[chrisbchips]

Thanks Mr. Boombastic,

I have all the lines and valves installed, and set up the mix and tested the system last weekend, all seems to work well. Now its just the injector setup we're trying to get.

Thanks for your help!!

How is the 2.6 260 coming BTW?

[Mr Boombastic]

What sort of injector problem are you having? Not enough smoke??
Pre Heating can help with smoke, but they reckon a petrol engine doesn't need it.
What fluid are you using?

Slow progress on the Extra.
Should have it 99% finished this weekend. Mostly waiting on upgraded C/Fibre Rudder control horns, had to get them laser cut. Aust Post took 3 weeks to get them there.
It looks like we will be at Parkes Comp, hope to see you there.
Warren.

[chrisbchips]

Well we're still deciding on an injector design, we've been advised to use some regular brass tubing, which is then closed down to 0.2mm in diameter to limit the flow of smoke fluid, so as to stop condensing of the smoke further down the pipe. I just wanted to see what sort of desing other people are using with tuned pipes before we comit it to silver solder and header!

Looking forward to seeing the extra go, it should have some power with the 100 on pipes!!! and by the sounds of it its going to be pretty pimped out with the carbon bling!

Thanks again.

[Mr Boombastic]

Isn't your fluid flow governered by a pump or proportional valve setup. Model Engines do a small lightweight pump that runs off a receiver channel, needs a seperate battery pack.
There will be fluid residue in pipes. Some tends to accumulate on the internal wall and then blown out the pipe as a liquid residue. Pipes are better though as you get more 'hang time' for the fluid to atomise and burn more thoroughly in the high temperature (almost).

[chrisbchips]

Yes I have the dubro super smoker valve, didnt want to mess around with pumps and extra weight (minimal, but still) so I went with the tried and tested method, crankcase pressure and the dubro valve. But this valve still seems to act more like an on off switch in testing, there doesnt seem to be a proportional control of the flow. I've just heard stories of pipes not being so good with smoke, because the long length gives the smoke time to cool down and condense before it exits the pipe resulting in poor smoke?

[chrisbchips]

Ok guys, just to keep this thread alive for anyone else who has the same question. I decided to take the bull by the horns and jsut went ahead and silver soldered the copper injectors into the header. They had been crimped off in the ends to 0.2mm in diameter. I would post a photo but could not get a clear close up. I soldered the injectors into the inside curve of the header (photo attached) and no pre-heating. Tested the smoke this weekend, smoke oil was summer spray oil thinned 10% with kerosene. Photos attached, judge for yourself

[Jamieman]

Nice smoke Chris.
Well done.

[chrisbchips]

Thanks Jamie! Needless to say Im stoked with the results. Troy and I are looking to try some of the Super-Dri smoke oil, we found a supplier in brisbane. The summer spray oil is great, but leaves quite a mess, but it just wipes off. It cleans all the carbon out of your pipes though! (although it does leave it all over the plane!). Will you be flying at the PARKES comp??

[Jamieman]

Not sure yet.
My trailer is all framed up, just needs to be sheeted & wire for lights. If it's on the road then most likely yes.
Going to take me a few weeks to sort my 2.3. I'm happy with the CG, just need to dial in some more right thrust & go from there. Busy sorting the motor at the moment.

[chrisbchips]

Sounds good, hope to see you there!