[NSRCA-discussion] Serious Torque on the Nose of the Model - RESUBMITTED

[PhilS.]

Charlie, I suspect an additional factor in the complicated mix is the 
_instant_ torque that is a characteristic of the e-power systems...

On 12/4/2012 8:02 AM, Charlie Barrera wrote:
>
> I torqued the nose off of the fuselage of my WindS Pro. I have a 2 
> meter WindS Pro which I recently acquired from a good friend. The 
> model is probably 2 years old and has close to 200 flights. The model 
> had a contra rotating propeller power system installed before I 
> acquired it. The nose section had been modified to accommodate zero 
> degree down thrust and zero degree right thrust. I installed a new 
> Hacker Q80 motor on the nose, attaching it to the nose ring. I did not 
> reinforce the rear of the motor to the fuselage. I re-modified it for 
> 2 1/2 degree right thrust and 1 degree down thrust.  I reinforced it 
> amply and was confident in the installation.
>
> I made a normal takeoff at about half throttle. As I turned to a right 
> downwind, I powered up to about 3/4 throttle for my usual trim pass. I 
> was in a right bank, and was rolling to the right. I heard a very loud 
> "whack" noise. I continued my turn and only then did I realize that 
> something had changed. I managed to land the model, not realizing that 
> I had lost the motor. It was difficult landing because of the 
> resultant aft CG. The fuselage was missing the first 4 inches.  It was 
> also very apparent that torque had sheared the motor off the 
> fuselage.  I theorize that the combination of the right roll and the 
> power up caused a gyroscopic effect on the model, shearing the nose 
> off the model.
>
> I wanted to share this to possibly alert others to a nose ring 
> installation of their high power motors. Be aware of the forces that 
> can be produced by these high torque motors. I don't know whether 
> providing a rear brace on the installation would have made a 
> difference. I don't think so. The fuselage was "torn" well behind 
> where the rear brace would have been.
>
>
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-- 
Phil Spelt, KCRC President
AMA 1294 Scientific Leader Member
SPA 177 Board Member
(865) 435-1476v, (865) 604-0541c

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