A few comments, in the mode of constructive criticism:
1. The tubing seems to be rather on the small size, and
insufficiently stiff. Larger tubing with thin wall is
much stiffer than smaller thick wall tubing. One of the falling
derricks was sagging so much it looked like it might
buckle. There should have been a rope support to hold up
the middle of it.
2. No pulley was used at the top of the falling derrick.
Not doing this requires standing under the falling derrick.
With a pulley, you stand away from any danger and you get
a big mechanical advantage. (The rope is tied to a ground
anchor at the point where the end of the falling derrick
hits the ground).
3. The double falling derrick with dual hinges is very clever.
Most tapered designs don't need compound falling derricks.
Maybe they had no choice about the tubing.
4. This looks like it might wiggle a lot in the wind and
build up aluminum fatigue. It's hard to know if this is
happening until it falls down.
Rick N6RK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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