RV-4 Slider canopy
I have a slider on my -4. I started with John Haehn's blueprints dated 1995. I believe Van's may have contact info for him.
I wanted a slider because I couldn't find a reliable way to lock my canopy partially open for ventilation on the ground, a requirement in AZ. Two friends had their latches fail and ended up with damage as a result. Since then I've seen some clever solutions to that which would have eliminated the reason to go through all the work/rework to get where I am now.
John called for a dorsal fin on which the canopy tracks rearward. The plane at OSH used the -8 track on the turtledeck which is a better idea, but was not available when I started.
My canopy is all metal and had to be redone to get the stiffness necessary to prevent the sides from bowing out in flight. I enlisted some warbird pros for that. They solved the problem, but some of the solution came straight from their SNJ/T-6 experience and the result was a weight gain, but I don't have an exact number. Probably avoidable, but I was so burned out on building (DR, I hope you won't ban me for that admission) I couldn't wait to hand it off to someone else at almost any cost.
Some considerations for your conversion based solely on my experience:
It was ALOT OF WORK!!!
The windshield extends 11.5" to the rear of the panel and that restricts ingress/egress to the front pit. At my size, not a problem, but one size might not fit all. My windshield is the F1 Rocket/raked racer model.
Access is also restricted to the rear pit by the forward edge of the canopy when it is at it's most rearward position. This also means you have to be more careful loading baggage.
The rollbar must be lowered so the canopy will clear as it slides rearward. I am short, but have still given up some rollover protection.
I do not fly with the canopy open. The airflow pushes the canopy closed, though latches or detents would solve that. Also, I do not trust the canopy to stay on the plane much above 80-90 kts. That is not because I feel the construction is weak. There is just alot of air pressure coming up under the canopy sides as they go straight back while the fuselage begins to taper.
That said, I like my slider. The forward vis difference is minor, in my opinion, and I sure don't sweat as much waiting to take off. These observations are purely personal and probably relate to my first aviation memories sitting in the F4U's my Dad used to fly for the Marines. A canopy bow and fixed windshield just seem "right". Maybe that's the reason my panel is steam gauges, though I fly glass professionally?!
I am headed for an overseas assignment, so my plane will be unpainted a bit longer, but I'll try to get some photos posted if I have time.
Jim Graham
