instruments? * And why don't the instruments vibrate loose? *Please
keep the answer this side of a physics lecture.

They don't vibrate loose because there is no vibration! Without the
engine there are no serious vibrations except when rolling on a rough
surface.

I wouldn't be so sure about the "don't vibrate loose" part. On all
three gliders I've owned, two new, instrument screws have slowly
backed out. Eventually you will see empty holes in the panel and hear
funny rattling noises under the seat pan. (Don't ask how I know!)
Checking instrument screws, the screws that hold the glare shield in
place and so forth has become part of my annual.

John Cochrane