Fastback question - Ventilation?

[Foghorn]

I'm steadily building, I mean sanding, away at my FB canopy frame.

I've been wondering about smoke/fumes elimination with the FB canopy. Let's assume smoke in the cockpit, all electrical equipment has been turned off and the source has stopped producing smoke.

Does the air vent, heater vent or both provide enough pressure to remove smoke/fumes?

What if the source doesn't stop producing smoke.

Can the aircraft be slowed down enough to open the canopy to the taxi position? I'm thinking this is a last resort for relief/survival.

Now back to sanding.

Thanks,

[Scott Hersha]

If you try to open the canopy to the taxi position In flight, you’ll most likely loose the canopy. That may be what you want if you’re still on fire and thinking of bailing. It may be difficult to open the canopy anyway in flight, but if you get it started to open, it will most likely be gone very quickly.

Try this: while taxiing, open the canopy a little with a FIRM GRIP on the canopy lock handle, and then push the throttle up a little (difficult to do unless you have two left hands). When I did that, it tried to pull the canopy right out of my hand. I had to quickly reach across with my right hand and close the throttle.

Make sure you have the canopy latched in the taxi pinned position during normal taxi ops before you add anything more than idle RPM, or you might get a surprise.

As far as smoke clearance goes, here is my observation..... when I first put a smoking airplanes system on my FB RV8, And I was trying to figure out the best flow setting to give me good smoke without going through 4 gallons in two minutes. Well, on one pass with “smoke on”, I guess I had it dialed up a little too high because the cockpit went IFR - on the inside. I turned the smoke pump off and it cleared up quickly with just normal vents open. I eventually discovered if I had the back seat vent closed, and dialed the flow rate down a little, that didn’t happen, but to answer your question, opening the vents for smoke clearance should work well, as long as you have put the fire out.

[DanH]

Jeff, impression only, based on operating the canopy on the runup pad; there is a good bit of lift even at low RPM on the ground. I would not want to be the first to try moving it from the closed position to the taxi position while in flight.

While on the subject, I scared myself a few times by bumping the canopy release knob with my elbow while moving around the cockpit. I subsequently installed a safety at the release lever which doesn't allow the lever to rotate forward until moved out of the way. The downside is that with the safety in place, the latch cannot be opened from the outside. I considered the risk of losing the canopy to be well in excess of the need for external access by a rescuer. Your mileage may vary.

On the upside, the safety visually and mechanically confirms the lock pins are fully engaged in the airframe. Plus it made me comfortable about adding a second release lever and yellow knob at the rear seat location. The passenger can reach and disengage the safety if he drops his shoulder belts, after which he can open the canopy. A goofball passenger cannot release the canopy without reaching up alongside me to disengage the safety.

[Foghorn]

Thanks gents!

I figured the canopy opening in flight would a last resort emergency. I am glad to hear that the vent/heater will evacuate smoke/fumes from the cockpit.

Dan, Great idea on the safety. I'll look at doing something similar.

Now back to sanding....

Thanks,

[Pilot8]

Dan
I just completed converting my slider to a fastback and I’m interested in your canopy lock safety mechanism. Would you mind posting a photo?

Thanks
Sam

[DanH]

Originally Posted by Pilot8

Dan
I just completed converting my slider to a fastback and I’m interested in your canopy lock safety mechanism. Would you mind posting a photo?

Sure. No photo on the hard drive, but I'll shoot one next trip to the airport.

[David Paule]

Van's sells an "RV-4 Canopy Safety Latch," Bag 951, that's sensibly-designed.

Here's the kit contents:



Don't know if it'll work on any other RV and am not far enough along to trial-fit it on my RV-3B project.

Dave