Smoke system smoking the cockpit

I tested the smoke system the other day on the Radial RV-8 and some smoke started to filter in the cockpit immediately. I'm wondering if anyone else flying an 8 has had this problem? The only openings on the belly that lead to the cabin are from the flap pushrods.

BK

Smoke system

BK,

I have a -4 with a smoke system and the only time I get a little smoke in the cabin is when I pitch out from an overhead with the smoke on and start lowering the flaps. Sometimes on the ground testing the smoke before takeoff I get some smoke because there's not a lot of airflow to keep it away from the cockpit. All other times I never smell it cause the flaps are up.

I have learned to turn the smoke off in the break.

Brothers Harmon Rocket and John Harmon's Rocket gets it inside. We just talked about it 2 weeks ago.

Very common. The only real solution is to keep positive pressure in the cabin with open fresh air vents. Does not keep it all out, but does 80% of it. I took videos years ago trying to find out where it was coming from. Mostly from the tail. I tried all kinds of solutions. None did anything as the smoke is relentless for any opening.

Scary huh!!!

I've got two planes with smoke systems. And yes, smoke eventually enters the cockpits when SMOKE ON which is unnerving to passengers if I have forgotten to prebrief it may happen. "WE ARE ON FIRE!!!" I try not to forget.

More disturbing to think about however as pilots is THAT SAME EXHAUST IS ALWAYS IN THE COCKPIT, you just don't see it without the addition of smoke oil and it's usually not enough exhaust without smoke oil to detect the odor. (Pure monoxide is odorless anyway so you won't smell it unless infused with oil, rich mixture, etc)

A flight surgeon bud always flys with his oxygen monitor and on extended flight he tests his blood oxygen level. It's kind of sobering.....

Keep the cabin vents open!

Hi Brian,

When flying my -6 and using the smoke system, I have to have my cabin vents open at least partially, as others have said. If not, the smoke will fill the cockpit. The smoke comes up the fuselage past the wing and sneaks in thru the aft part of the canopy.

Still would not trade it! Have fun!

The only time I've ever had any issue with smoke in my cabin is when one of my 4 injectors was leaking at the exhaust, and I used the smoke diluting take off.

X

Smoke

I don't know where I learned this, I think it was from someone here on the forum. I picked up a pair of 2" circular fixed vents from the local 'aviation store' and painted them to match the airplane. I oriented them with the vents facing aft to create a vacuum of sorts. They are mounted below the horizontal stabilizer on each side of the aft fuselage. The left one is incorporated into the lower aft round inspection panel and the other is on the same spot on the opposite side.

I used to smell a little smoke at first with the new system from Marvin at Smoke System Helper but now with the canopy closed, the vents open and the flaps up in flight I never detect or smell smoke residue anymore. There may still be a path for smoke into the cockpit but with the aft fuselage vents there seems to be an exit strong enough to pull anything out. I will still detect a little smoke on the ground doing a smoke check or in flight if I put the flaps down.

Yeah I know it sounds crazy and all the smart Aero guys may call this bunk but all I know is that it works on my -4. Mileage may vary on other models.......

Out of town right now but will try to get some pictures posted next week.

Smoke in Cockpit?

I think it "smells like victory!"

All good comments and suggestions. It's not a show stopper for me. I think I'll mount a go pro looking in the aft cockpit first and then go from there.

All the best,
BK

I used to get smoke in my RV8 if I didn't have the back seat air vent open. The first time I used it, my cabin went IFR inside. I reached back and opened the back vent and it cleared up quickly. I also had to turn down the volume. I went through 4 gallons in 2 minutes - but it looked amazing!