Patrick,
The January Aeronca Association newsletter has a suggestion for a slider window lock for the Champ: use a light-pull bead chain secured through a hole drilled on the inside front window channel, and the chain is then latched through a kerf cut in the side window fram at the front. I secure it for the winter by cutting an alder twig to brace the front window shut when it's tied down. So what if it vibrates open, it's probably about time to stretch my legs anyway. Tony Markl has the tie-down rig written in the Aeronca newsletter, too. We use two or three lines on the more upwind wing, and each single line should be sufficient to secure the load, which may approach 11Gs.
The PA-18 Cub windows that I'm used to seeing are hinged at the top, with a wing-mounted catch similar to that for the door.
Hope this helps,
Charlie Branch at CKU Cordova, AK
[Aeronca Aviators Club http://www.aeronca.org - Admin]
