On 4/16/2013 9:04 AM, Bob K6UJ wrote:
Steve,
The sleeve would definitely add strength. The lateral force from the wind load
on an antenna mounted on the mast puts the most stress
at the bottom of the mast, think of a 16 foot lever arm. I would find out the
yield strength of your aluminum mast and do a
check of the maximum antenna load you should use. Aluminum has a much lower
yield strength than a steel mast so you need to be careful.
There are calculator programs available to help you figure out the load rating
of various mast materials.
There are many alloys of widely varying strength from both a flexibility
ans yield strength. The most common, 6061T6 is neither the strongest,
nor cheapest.
I use a lot of the 6061T6, but not in antennas. A 2" diameter piece with
0.25" wall, 24' long is heavy and when used as a gin pole displays a
surprising amount of flexibility.
73
Roger
Bob
K6UJ
On Apr 16, 2013, at 8:31 AM, GW4BLE wrote:
I have a question concerning 'sleeving' (can't think of a better way to describe it) - I
have a 16' x 2.5" OD thick-wall aluminium tube that will be used as a stub mast,
would inserting 6' x 2" OD thick-wall aluminium tube into the bottom of the tube
add to its' 'strength' in any way or would it just add unnecessary weight?
Sliding it in makes quite a snug fit, but not exactly 'tight'
Steve
GW4BLE
Sent from my iPhone 4S
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