Opening Windows on a Rans S7
I always like to have the option of opening windows on my aircraft.
When flying low and slow I enjoy the open air feeling and the clear view.
It's essential for photography, since shooting thro the plastic so often gives disappointing reflections.
This is how I did it. It was fairly easy to do, low cost, and effective in the air.
I did both front and rear windows. The windows slide in channels. There's enough room in that enormous S7 door for both front and rear windows to be open at the same time. I didn't record dimensions, and I don't have access to the aircraft now, but this photo should give an idea of the spacing.
There are two tubular stiffeners, a vertical one at the back and the sloping one at the front. These were needed to give some support to that large area, which is a bit floppy even before cutting the openings. The position of the front one was chosen so that from the pilot's eye it concided with the front strut so as not to obstruct visibility. They are riveted to the top and bottom and to the lower channel.
The channel is constructed of two strips of polycarb, one 20mm wide and the inner 10mm. Thickness of the inner one is the same as the window material. They are riveted together with an 1/8" washer on the inside to spread the load. I used the softest common aluminum rivets I could find and pulled them very gently... That lip on the back edge of the window is needed to stiffen it, and was bent cold in an ordinary brake. The channel is lubricated with the stuff for zippers on clothing.
The aluminum angle stiffens the front edge of the window. Need to have a clearance as shown at the top edge of the window. The windows slide smoothly, and have enough resistance to stay put anywhere.
On the very first photo you can see a black spot at the right side. That's a button of felt material stuck to the window to keep the sliding polycarb surfaces apart to avoid scratching. There's a small draft into the pax seat that enters the back edge of the front window thro this space. Could seal that by felt all the way.
The deflector at the front edge keeps the draft for the pilot comfortable.
With both windows open the circulation is, in the rear, forward, and out the front window.
The static port is in the wing, open to the cabin, so same pressure.
Open the front window and the VSI goes up 4 kts.
Both front and rear windows it goes up 2 kts.
Just the rear window open, no change.
Enjoy that open air feeling!