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Another home-made smoke system

gear1

Well Known Member
A partially finished smoke tank for the front baggage well came with my RV8 when I purchased it, so I decided to make my own system by completing and painting the tank, installing a submerged pump in the tank, and doing all of the plumbing with stainless braided hose. The system weighs less than 5 pounds excluding the firewall forward plumbing. The tank, about to be installed is shown below:

SmokeTankobliquemar1814.jpg
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The pump system consists of an automotive in-tank pump from TRE Performance (thanks to the idea from Alan of Anti-Slat), a home-made pressure regulator, and a flow regulation valve obtained from McMaster-Carr and Marvin Helmsley’s injector nozzles. Standard aircraft hardware was used throughout.

SmokePumpSystemmar1814.jpg
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The pressure regulator was made from a bulkhead run “T”, with the side leg bored for a ¼” ball and a fine spring for pressure control. Bleed holes were drilled at the relief point. The pressure regulates to 32PSI.

SmokeSysPressregulatormar1814.jpg
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The tank fits into the drop area of the forward baggage compartment.

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The system is controlled by a relay, which is grounded through a switch on the throttle. Power is supplied through a 15 amp circuit breaker and a smoke "arm" switch on the instrument panel.

SmokeControlSwtchmay1514.jpg
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This was the first test of the system

SmokeFirstTestmay15.jpg
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Since the firewall forward line to the left side of the engine is longer than the line to the right side, a flow restrictor orifice was inserted in the bulkhead “T” outlet serving the right side of the engine. The outlet was drilled out to 3/16” to a depth of 1/4" and a number of restrictors were fabricated for test. We ended up using a restrictor with a 1/16” hole to get balanced flow to both nozzles.

So far, great smoke at 1/3 gallon per minute of smoke oil!
 
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Neat system. Especially the submerged pump. I think you will find the in tank pump will have difficulty making the flow rate you need for good smoke at speed. Your flow rate needs to be at least 1/2 gal/min. It takes a pretty big pump to do that with oil. Let us know how it compares with your other smoking friends in the sky.
 
I think you're onto something with that submersible pump! Can you tell us the rated flow and pressure?
 
Submersible pump

The pump is from TRE performance (www.treperformance.com/fuel pumps $70.) and is rated at 255 liters/hour (67.5 Gph) at free flow and 210 L/hr (55.65 Gph) at 35 psi. Typical usage as pointed out by Kahuna is .5 G/min or 30 Gph. The pump is a positive displacement type, and is capable of 140 PSI at 5 Gph. Therefore a pressure regulator is required. At 35psi the pump pulls 10 amps, with the draw proportional to pressure. It might be possible to use a smaller version of this pump to cut power consumption

I am beginning to wonder if this type of pump could replace the Airflow Performance that is so common in RV aircraft.;)
 
Another home made smoke system

Don't know how many of you are aware, but ALL of todays (and last 10 yrs) autos use those type of in tank pumps for supplying fuel at high pressure at their fuel injection....I have considered using on fuel tanks in RV4 as will have fuel injected engine. Pumps are available with various pressures and wide range of prices.They also have a very great filter attached that in auto use lasts thousands of miles unless fed poor dirty fuel.....Tom
 
The pump is from TRE performance (www.treperformance.com/fuel pumps $70.) and is rated at 255 liters/hour (67.5 Gph) at free flow and 210 L/hr (55.65 Gph) at 35 psi. Typical usage as pointed out by Kahuna is .5 G/min or 30 Gph. The pump is a positive displacement type, and is capable of 140 PSI at 5 Gph. Therefore a pressure regulator is required. At 35psi the pump pulls 10 amps, with the draw proportional to pressure. It might be possible to use a smaller version of this pump to cut power consumption

I am beginning to wonder if this type of pump could replace the Airflow Performance that is so common in RV aircraft.;)

Craig,
Have you tested the flow rate of the oil out of the pump? Looking at your picture (always hard to tell), Id say your rate is ~half of what it needs to be. Could have been just you testing. But Im interested in the rate out of the injectors. A catch can and watch is all that is required.
 
Flow Rate Testing

Kahuna,

Good question. Yes we did test the flow rate through the injectors as you describe. At about 1 turn on the McMaster Carr needle valve we were getting more than 1 GPM flow from the exhaust pipes. The photo was taken at 1/2 turn of the needle valve, which yielded exactly .5 GPM flow from the pipes. The test RPM was 1800, and resulted in the belly of the aircraft being covered with oil. I think the limited smoke problem was the result of not enough exhaust flow relative to the smoke oil flow. We dialed it back to about 1/3 GPM for flight test, and the belly has remained oil-free. I will get some photos tomorrow showing the smoke. We did a 5-ship flyover over the Veterans Home in Monte Vista CO on Memorial Day, and my wingman and ground observers reported good smoke with a long hang time.

I will also try a ground test with the valve completely open to see what the maximum flow rate could be. Hopefully I can do this tomorrow, too.

Thanks, Kahuna for insisting that we document this experiment. One question for you, Kahuna: what would you use a substitute for good smoke oil? I am nearly out of the initial 5 gallon supply, and more is on order, but a couple of gallons of something will be required for the maximum flow test.

Thanks, everyone for your inputs. Nearly all of the ideas for my system came from the capable folks on Van's Airforce!:)
 
Excellent report. You have proved me wrong on that pumps ability to flow the rate. And its doing it at twice the necessary rate. Well done. Pumps and related junk take up valuable baggage space. Love your solution.

As for an acceptable solution, a couple of us have used diesel in a pinch. It does stink and does not smoke as well, but its good for tossing overboard for testing, and is readily available.

Great project and thanks for sharing.
PS, now about its ability to smoke inverted:) A flop pump?
 
Source for Smoke Oil

One question for you, Kahuna: what would you use a substitute for good smoke oil? I am nearly out of the initial 5 gallon supply, and more is on order, but a couple of gallons of something will be required for the maximum flow test.

!:)

I did a little research and found that most smoke oil is a Parrafinic Type 1 oil which is usually White Mineral Oil. Oddly enough it is rated for contact with food and smokes well because of the high paraffin content. Call a local wholesale oil distributor and ask for Agricultural Smoke Oil. I am told they use it to check winds when dusting. I have been getting it in 5 gal buckets but you can get it in 55 gal as well. You will find it has a yellow tint but practically clear and works well in wick style lanterns as well. It burns very clean with a little clear residue and what is there comes off very easy with "Scubbing Bubbles". It may not be as good as the high dollar stuff but it looks the same coming out of an exhaust pipe.

Depending on the distributor, it will cost about $60-$70 a 5 gal bucket FOB. It doesn't stink and works well. I would guess it at about 10 weight. You can't light it with a match but put a paper towel in it and it will burn nicely. Send me a PM if you want the specs on it. Hard for me to justify diesel when this is readily available and seems a lot safer and cleaner than something like diesel or transmission fluid.

You can also order it from your local Bumper to Bumper Autoparts store in Ark, La, Mo, Ms, East Ok, Tn, and East Tx. Part number is 12805 LUB.

Hope that helps!
 
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Inflight smoke photo

Kahuna,
This photo was taken in flight this morning. We were out doing a bit of tail chase. Do I need to add more smoke oil?

 
After......

a weekend of watching War Movies in honor of Memorial Day, your picture makes me want to scream out, "Bail out Craig, bail out!".

Great shot!

Mike
 
Higher pressure pump, smaller orifice at the injectors should equate to good smoke using less oil due to better atomization.

I have a similar pump for my Rocket (a Carter, same as what AFP uses) and am using it because thats what I had laying around.

I welded 1/4" NPT bosses to both exhaust pipes so I can change out the orifices easily, negating the need for a needle valve.
 
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Regulator oriface as a nozzle

RocketBob,
Your idea intrigues me, Bob. I may try to machine up some parts to substitute the nozzles with orifices directly injecting into the exhaust pipe. I need to sketch up some ideas....

We did find that we had to introduce a restrictor into the right side feed line to balance the flow between pipes. This is because the line to the left side is about 30" longer than the right side.
 
Higher pressure pump, smaller orifice at the injectors should equate to good smoke using less oil due to better atomization.

I have a similar pump for my Rocket (a Carter, same as what AFP uses) and am using it because thats what I had laying around.

I welded 1/4" NPT bosses to both exhaust pipes so I can change out the orifices easily, negating the need for a needle valve.

Bob

What are you using for your injectors?

I have 1/4" NPT bosses welded into my pipes and have been having trouble locating replacements. My injectors keep clogging and they are pretty well worn out.

I've been drilling them out to .060" and pumping about .7 gpm for great smoke (4:1 ATF and diesel) but they are clogging regularly. Yes, the ATF is filtered, I think its just coking up in there. I'm using the ShurFlow pump from Marvin.
 
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What did you do for a vent?

You obviously have one or it would collapse the thank, we just don’t see it.
 
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Bob

What are you using for your injectors?

I have 1/4" NPT bosses welded into my pipes and have been having trouble locating replacements. My injectors keep clogging and they are pretty well worn out.

I've been drilling them out to .060" and pumping about .7 gpm for great smoke (4:1 ATF and diesel) but they are clogging regularly. Yes, the ATF is filtered, I think its just coking up in there. I'm using the ShurFlow pump from Marvin.

I don't have the injectors made up yet but I have a CNC turret lathe so when I get around to it, shouldn't be a problem. Basically my thought is to have a 1/4" NPT body with a small insert that is the actual injector, sandwiched between a spring and a ball and a 1/8"NPT - 3AN fitting on top. I made my bosses long enough so that the injector is shielded. With higher pressure it shouldn't be a problem to blow thru a clog much like a diesel injector. The insert itself will probably be made of Inconel as I have some cutoffs that came from a friends shop that does a lot of aerospace stuff.
 
Kahuna,
This photo was taken in flight this morning. We were out doing a bit of tail chase. Do I need to add more smoke oil?


Smoke looks good to me. Your getting the flow rates as measured on the ground.
 
The pump is from TRE performance (www.treperformance.com/fuel pumps $70.) and is rated at 255 liters/hour (67.5 Gph) at free flow and 210 L/hr (55.65 Gph) at 35 psi. Typical usage as pointed out by Kahuna is .5 G/min or 30 Gph. The pump is a positive displacement type, and is capable of 140 PSI at 5 Gph. Therefore a pressure regulator is required. At 35psi the pump pulls 10 amps, with the draw proportional to pressure. It might be possible to use a smaller version of this pump to cut power consumption

I am beginning to wonder if this type of pump could replace the Airflow Performance that is so common in RV aircraft.;)

Thanks for sharing. That relief valve/regulator is brilliant. And yes, might be some fuel applications at hand also!

Latest smoke fluid we've been using is the petroleum based concrete form release oil.
 
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Thanks

Thanks, Kahuna and Bryan,

I appreciate the feedback from you, and everyone else who has contributed to this thread.

Bryan - I am working with a local oil distributor to try to find some of that concrete form oil.

Kahuna - I have not forgotten my promise to get the maximum flow rate for my system, as I have spent the last week rebuilding and repainting my cowling. It was beginning to look shabby. I'll try to get it done tomorrow:rolleyes:
 
What did you do for a vent?

You obviously have one or it would collapse the thank, we just don?t see it.

What I did for my removable tank is to install a -4 AN bulkhead in the bottom of the fuselage below the rear baggage, the make up a small piece of 1/4" aluminium hard line bent in a 90 facing forward, flare, and attach to the bulkhead fitting. Looks like a mini pitot tube.

Internally I used Summit Racing braided steel over nitrile (over kill I'm sure) and ran it up the back of the rear baggage and out a hole with a grommet. I used Summit Racing a -4 AN female hose ends and a quick disconnect fitting similar to what people are using for aux fuel tanks. In fact, I intend to use the vent for a removable aux fuel tank as well when needed.

Its kind of cool after running the smoke to pop the cap on the tank to refill it and have a bunch of smoke come out of the tank.

Be careful not to create a siphon. Don't ask me how I learned that one. :eek:
 
Vent on home made smoke system

I used a standard Van's fuel cap. Inside the big "O" ring and between the cap halves is a small chamber. By drilling a 1/16" hole in the upper and lower halves, a surge chamber was created. We the drilled and tapped the upper half for a 1/8" pipe and installed a vent filter normally used in the brake fluid reservoir. The aircraft does not have an inverted oil system, so negative "g" is avoided. So far the vent system is working great. It would easy to use a pop rivet vent to the outside do the aircraft for an inverted system. I have to credit the idea for the vent system to Mel McGyver, a retired mechanical engineer who helped with the smoke system installation.
 
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