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[TowerTalk] Rotor specs, are they a bill of goods ??

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Subject: [TowerTalk] Rotor specs, are they a bill of goods ??
From: "Jim Thomson" <>
Date: Tue, 4 Jan 2011 06:52:36 -0800
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OK,  I see mentioned on most rotors... specs like   "start up torque"   and 
"running torque"    and also "stall torque" 

I also notice on most rotor's, the start up current is 2-4 times the operating 
current.   The  OR-2800 has a start up torque spec that is
slightly higher than the running toque. [3200 in lbs  vs 2800 in lbs  for the 
older AC version].  The DC version has similar ratio specs.

Then we have the HDR-300 and ham-4/5 rotors that spec  stall torque only.    
Then we have prosistel rotors.... whose start up torque is exactly 
double their running torque.   And  why are "in lbs"  used at all ??     Why 
not just divide by 12 and obtain foot lbs....that I can relate to.
800 in lbs  might sound great on a ham-4.... but it's only 67 ft lbs..which is 
not very much at all.  

I can sorta understand maybe..perhaps the concept of start up torque being 
slightly higher than operating torque..for abt all of 1-3 seconds max.
The stall torque figure  sounds flaky too.  Run the rotor in a test jig with a 
1-2'  torque wrench attached to it... and let it freely rotate  till it hits
a solid concrete wall... then  watch the torque wrench  wind up...and stall.   
Sure you have max torque... you also have zero rpm on both the rotor's
mast shaft..and also the motor itself. 

Are rotor makers  trying to sell us a bill of goods  with BS specs ?   IMO, if 
you can't rotate once or twice a year  because of extreme winds.. who cares.
However the braking sytem has to be able to handle the ant  at a high 
wind...which I think is more important.   While on the same subject... why
aren't any of these various yagi's   ever using torque compensator "plates"  or 
..."sails" ?     They are easy enough to implement.   I suggested to Mark @ F-12
that one or more of his superb ele  to boom brackets  simply be flipped 90 
degs... and oriented  vertical,,and used as a torque compensator.   His are 
light weight
and only the thinner  1/8"  brackets  are required.   He agreed, it's a cheap 
and easy way to add torque comp  to any F-12 boom...since he has loads of em 
Once riveted  to the boom... they are not going anywhere. 

Later... Jim   VE7RF  

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