At 07:57 AM 12/13/1999 -0600, n4kg@juno.com wrote:
...
>When pushing the load limits, a better measure of capacity
>is needed. The problem with boom length only specifications
>is that they do not account for element size and weight. The
>problem with Wt X Boom specifications is that they do not
>account for element WEIGHT DISTRIBUTION. A 2L Yagi
>has ALL of it's element weight at the ends presenting a
>worst case scenario. A multi-element multi-band antenna
>has it's element weight (and often boom weight) distributed
>along the boom. Thus two antennas with equal boom
>lengths and equal weight can have VERY different torque
>requirements. Examples: 2L40 vs. 3L20 or 2L80 vs. 5L20.
>
>It should be a simple matter to determine rotor stall torque.
>Simply attach an arm (boom) to a mast and measure the
>force in a restraint applied perpendicular to the boom.
>Force X distance (from the mast) = torque. If the imbalance
>is a problem, apply two restraints at each end of the boom
>and sum the forces. Any Mechanical Engineer worth his
>salt should be able to make this determination.
Don't you also need to add in maximum wind-induced torque, if you're
looking for a true worst case?
73, Pete N4ZR
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