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Smoke Helper Smoke System

Smilin' Jack

Well Known Member
I completed the installation of Marvin Homsley smoke system on my RV7 Saturday.

I had the desire to make the tank removable and thus took a little different approach in case I needed more baggage space.

The empty tank pump and valve and hoses weigh 10 lbs and since they are in different areas of the aircraft the weight behind the seats come to 8 lbs.
The Valve, weighs in at a pound, to control the oil flow was mounted next to the pilots hip where it could be reached in flight.

Starting with the tank I scribed the legs to the floor and clamped the tank to be in alignment with the flap enclosure. I used some 3/4 X3/4 angle left over from the build and made them 2 inches long and popped riveted them to the floor once I had the legs positioned. I attached the tank using AN 3-4 hardware with castle nuts and safety pins on the floor of the aircraft, the upper portion of the tank that goes between the cross member on tip ups I used 3/4 inch spacers and then used AN 3-12 bolts and castle nuts and safety pins.
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On the pump I mounted behind the pilot seat using rivnuts and used an awl to locate the holes in the carpet to put the screws through
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I used a unibit and made two angle brackets and riveted them to a piece of .025 aluminum. Using the unibit I made the holes in the angles really snug to fit over the input and output of the Valve. Like I stated before this left me able to position the valve near my hip so I could reach it.
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I installed the T fitting after making two washers for the fitting to pass thru the fire wall. And ran the lines to the number 3 and 4 exhaust pipes since I have a 4 pipe system about 1 1/2 inch below the EGT probe and about 4 inches below the cylinder.
We learned that only a quarter turn produced adequate smoke from the system
Jack
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I ran it up along the side to the spar cap on the side where it meets the floor plans I cut the sub mat for the carpet and then used 3 adel clamps with the clamps positioned on the top side floor plan next to the side cover and then on the top forward screw of the floor plan that covers the spar using the floor screws and a washer.
The 3rd adel clamp went on about mid way along the side positioned vertically to the floor holding the hose down on the floor under the carpet. Then behind the fuel vent and penetrated the fire wall just inside the brake lines come out in the middle of the V that is formed by the angles on the fire wall. if you measure good the spacers will fit on the inside just perfect in the V. From there route the lines up and used stand offs to keep the braded hole off the engine mount.

I used blue painters tape to tape the braided line. Then used my bandsaw to make the cut in the braided hose. I have a fine metal blade in the bandsaw and it makes quick work of cutting the stainless steel braid. Separate the plastic hose inside from the braid slightly using an awl and push on the compression washer ( make sure you put the fittings on the hose first) use the side of your work bench to push the compression washer on. Then push in the center fitting into the plastic hose using the side of your work bench and you've completed your fitting.

I cut out 2- 1 1/2 in spacers in .063 aluminum using a hole saw and then used an unibit to open up the 1/4 hole made by the hole saw to fit the T fitting and allow it to be snug on the firewall since the fitting is very loose if you don't provide some spacers to take up the space.

Hope this helps... it went pretty fast... but a helper is great to hold the T fitting in place while your under the panel.

Jack
 
I also am a fan of Marvin's system. I thought I would post a few pictures showing the finished product and how well it blends in.

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Good installation John, I thought about mounting the valve where you did but I could not reach it.

Marvin is great to work with, we had a few discussions since his recommendation is to mount the nozzle's on the No 1 and 2 cylinders exhaust pipes but I have a 4 pipe system and it worked great on the back two cylinders. . Most planes that have smoke have a 4 into two exhaust or 4 into one. It is amazing how little you have to open up the valve to get smoke.

When we first tested the smoke on the ground we had the valve open about a full turn fired up the engine and proceeded to coat the ramp with oil... not to mention that it was dripping off the bottom of the plane :)
I told the airport manager we were just sealing the asphalt.

Jack
 
Hi John,

Thanks for the installation info, good description. One more question. How did you route the hose over the spar cap (photo maybe)? Did you just lay it over the spar along the angled vertical support and then down the front side of spar and under the carpet? Just asking because for some reason I just don't like the look of the black hose sitting on top of spar in clear view. Maybe I'll make some sort of cover to hide it??

Thanks
Bill
 
Jack, You are right that I can't reach the valve if I have a passenger. When solo I just tilt the seat forward and good to go. I have not had the chance to determine what the right valve setting is yet so I am glad to hear very little may be fine. I have been running at 2 turns open. I am using used ATF, What oil are you using?

Bill, Routing the line was my biggest concern. After looking at all the options like over the spar, aluminum line, thru the side wall spar support above the rudder cable I went with a thin wall oil compatible line that is smaller OD and much more flexible than the heavy black one that is supplied. I put a 3/4" hole thru the spar web and a snap bushing then ran the line around the edge of the sidewall which is virtually invisible with the carpet in place.

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Here is a picture of the hose as I ran it. Since I don't know how long the hose last thought it would be prudent to have it where I can replace it easily. With the seat cushion you really don't see it.
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Jack
 
Another Question for you Smokers>

I have been told that my smoke does not turn off very smartly and that I need a check valve. Does anyone have any info on the appropriate valve to use? In particular, what the cracking pressure should be?


Thanks in advance
Bill
 
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