Suction cup mounts and altitude

[scsmith]

I've recently started flying with an iFly720, and I have been using the suction-cup ram mount it came with. I was a little skeptical of the suction mount based on past experience. Yesterday was my first long flight with it, over the Sierra. At about 9000 ft, the ram mount fell off the panel.

I remember 'back in the day' in sailplane racing, before we had GPS, we used instamatic cameras mounted to the canopy rail to take pictures of turnpoints to verify that we flew the course. Some folks would try suction cup mounts on the inside of the canopy to mount a camera. Invariably at high altitude they would fall off.

At 9000 ft, the atmospheric pressure is reduced about 30%, and that is enough loss for the grip to fail with the weight I had on it.
I guess I'll have to make something more permanent.

[Norman CYYJ]

I use suction cups to hold my sun shades on the canopy and they stay on from sea level to 18000 feet.

[John RV8]

My Ifly700 suction cup mount would not stay in place for more than about an hour and a half even in cruise below 5500'. I finally removed the suction cup and mounted it with a bolt to an aluminum plate which can be installed/removed with one screw.

[Mark Albery]

What was the air temperature?

I used to find that the suction cup that I used with a Garmin antenna would fall off when the temperature dropped to zero. I don't know if it was sublimation of water vapour or the loss of elasticity in the rubber, but it seemed to be fairly consistent regardless of actual altitude.

[scsmith]

Originally Posted by Mark Albery

What was the air temperature?

I used to find that the suction cup that I used with a Garmin antenna would fall off when the temperature dropped to zero. I don't know if it was sublimation of water vapour or the loss of elasticity in the rubber, but it seemed to be fairly consistent regardless of actual altitude.

Temperature may also be a factor. It was 31F outside. Not much cabin heat makes its way up to the panel.