Stuart,

I'd gone over the weights very closely before buying the batteries. The problem is you run into a Catch-22 without the batteries. I couldn't build my battery-mounting tray until I knew where the CG was going to end up, but I wasn't sure how much weight the mounting tray would add. Also, without the batteries I wouldn't be able to get the tray to perfectly fit the batteries. I built cardboard mock-ups of the batteries to give me some ideas, but they were of limited use not being the same weight. I even brain stormed on how to make my mock-ups the same weight, but finally decided just to take the plunge.

These batteries are sandwiched with phenolic plates that protect the batteries. This allows you to clamp down on the plates without putting pressure on the cells. Due to this I wanted to build my mount perfectly to apply pressure to the plates.

As a contingency plan I took into consideration the size of the TP batteries when building the battery tray, glad I won't have to resort to that .

At NATS they usually have a courtesy weigh in day where you can weigh with their scale. If I’m over weight I can always remove my RX power switch and just plug the leads in directly, this will buy me a few grams to make me legal. I don’t think my scale should be off more than 10 grams.

Keith B