Rick (W-A-one-R-K-T) wrote:
On Tue, 07 Aug 2007 08:37:46 -0700, Jim Lux wrote:


Exactly... but don't expect it to stand up to much wind load
40 foot lever arm on a 1 foot plate, and it's pretty easy to lift the
tire off the ground.


Actually I was planning to use it with my motorhome, under the rear
tire... good luck getting THAT tire up off the ground.

One might think so at first glance, but here goes with a short scenario
(I was looking at using the roof rack on my car to stabilize a portable
mast)..
http://home.earthlink.net/~w6rmk/antenna/mastcar.htm has details..

40 ft mast 2" in diameter in a 80 mi/hr wind has a moment of 2200 ft lb.
if the distance from fulcrum to tire is 1 foot, then the up force on the
tire is 2200 lb.

So, your RV won't be lifted up, but my 3000 lb car would.

And, of course, if it's only a 40 mi/hr wind the load is 1/4, etc.

In practice, most people use a fairly lightweight mast and let it fail
before it damages the car.