Adding In-flight Smoke Capability to the RV-12


Inspired by David Valcik's and Steve Garrett's postings, I ordered the following materials for my RV-12:
 I first drilled a hole in the firewall at the same location David Valcik put his, and installed the aviation bulkhead fitting.  Put a short piece of flared aluminum tubing to make a transition to the 1/4 ID automotive fuel line tubing:

FWF lines

The preheat unit from SkySmoke was then clamped to the back of the Rotax muffler, and the copper line provided by SkySmoke routed to the right rear exhaust just below the curve.  The hole needs to be drilled 23/64ths then tapped with a 1/8 NPT tap to screw the injector in place.
EngineDetail

With the FWF part done, I fabricated a bracket from 0.063 angle for the tank, that would fit between the stiffeners on the baggage compartment wall, behind the pilot seat.  Closed the ends with more 0.063 riveted to the main angle piece, and drilled it for the bracket supplied by SkySmoke.  In this photo you can also see the solenoid valve (needed because the entire assembly is above the level of the injector, to avoid siphoning), which is attached with a small piece of 5/16 ID fuel line to the tank outlet.  The solenoid valve is threaded for 1/8 NPT fittings.

Tank Bracke Rear View

I put 8-32 nutserts on the end pieces, since there was not room for a regular platenut.  Here you see the pump mounted above the level of the tank.  This turned out not to be usable, since the pump doesn't have enough sucking power to prime itself and pump a steady stream without bubbles when mounted at this location.  After the first flight, I unbolted the pump and moved it down to the level of the solenoid, where it could be gravity fed.  (The amount of smoke quadrupled as a result of this change).  I terminated the wires for both pump and solenoid in a Molex MateNLok connector, so both would be energized at the same time.  The brass angle fitting is the same one used on the RV-12 brake cylinders, with a short flared piece of 1/4 aluminum tubing.

BracketEnds
Since I have the baggage compartment carpet kit, I wanted a clean installation with minimal upholstery disruption.  Fabricated a piece of 0.050 aluminum with a tab sticking through the carpet, and riveted it to the wall stiffener.  Forward side just required a hole in the larger sidewall stiffener.

SideWall bracket

The current configuration (which still needs a bit more work to fasten the pump at the base of the tank) is shown here.  Solenoid valve prevents leakage and siphoning, and when energized the pump fills by gravity and creates a strong fluid stream.  The yellow output tubing runs on the back side of the U channel over to the passenger/co-pilot side, and from there underneath the armrest and behind the upholstery forward to the bulkhead fitting.

Tank Assembly

I picked up power from the 12volt accessory outlet, and put the switch near the floor below the power outlet to make it relatively inconspicuous, and minimize the chance of inadvertent activation (particularly since the 12v outlet is connected to the battery and is hot all the time.)  Ran an 18ga. power wire back along the side of the tunnel, and a 22 ga wire forward in the bundle up to the space behind the instrument panel.



Switch

Mounted the blinking red LED indicator above the fuse panel.  Mostly for alerting about inadvertent switch-on, since there is no doubt in the cockpit when you are making smoke inflight! (more below on that):

Indicator

And with all in place, headed out for ground tests, and flight tests.  As noted above, with the pump above the reservoir, smoke production was light and spotty.  With a gravity feed to the pump, very impressive smoke production:

Ground testSunring
Approach

The online photo + movie version of the test flight is at:  http://www.photoshow.com/watch/Hr6FY9Tq

Issues to sill be resolved as of 10/25/2013:

The smoke production is so luxurious that some of it comes back into the cabin from somewhere behind the pilot seat.  Definitely not coming in either the canopy or the vents.  Most likely this is the square opening where the gear legs penetrate the fuselage.  Next improvement is sealing that opening with upper transition fairings and some duct tape.  Will update this page when I get the engineering solution for that problem.