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

[ehaury]

I don't know what caused Charlie's failure, we've discussed possibilities - obviously forces occurred that were beyond what the structure could handle.

Torque & precession have been with us since we stuck engines & props on the front of airplanes. They really haven't changed much with the advent of E power - actually went down with the use of lighter props.

I'd just like to offer that the Hacker Q80 design doesn't change much. The rotating outer member (Q80-14) weighs about 100g and rotates up to 7K rpm with an 1 1/2" radius. The rotor in a C50 also weighs around 100g, but it rotates up to 40K rpm on a 3/8" radius. The latter, with the gearbox, can probably apply torque quicker than the outie. Most other popular outrunners fall somewhere between these. (Be neat if someone actually made the calcs.)

I've lots of flights with the Q80-11 without issue (the Q80-14 is less powerful). It is firmly front mounted with also a solid rear mount. I think we all know the importance of a nose ring on a YS and there's been no success running inrunners without a rear support. While some have had success running the Q without a rear support (bet the prop was light), these things really need a more sturdy rear support (or very stout front mnt / fuse nose) than may be obvious.

Essentially something slightly different that adds to the learning curve, hopefully Charlie's experience and these discussions will prevent further occurrences.

Earl
  ----- Original Message ----- 
  From: mike mueller 
  To: Bob Kane ; General pattern discussion 
  Sent: Wednesday, December 05, 2012 8:26 AM
  Subject: Re: [NSRCA-discussion] Fw: Serious Torque on the Nose of the Model- RESUBMITTED


  Very cool video. I've learned a lot of neat things watching Youtube video's. Thanks Bob



  From: Bob Kane <getterflash at yahoo.com>
  To: Generalpatterndiscussion <nsrca-discussion at lists.nsrca.org> 
  Sent: Wednesday, December 5, 2012 7:07 AM
  Subject: [NSRCA-discussion] Fw: Serious Torque on the Nose of the Model - RESUBMITTED



  Charlie was spot on with his comment on torque, but there are two torque vectors at work, the first is the obvious force required to turn the prop and the "equal but opposite" torque the motor transmits to it's mount. If that was all we had to worry about, the single mount would probably be fine. But there is the other torque (gyroscopic precession)  resulting from attempting to move a rotating mass in the pitch or yaw axis.  Here is a good youtube video demonstrating the effect . .. .  



  http://www.youtube.com/watch?v=ty9QSiVC2g0




  Bob Kane
  getterflash at yahoo.com

  From: mike mueller <mikemueller at f3aunlimited.com>
  To: Bob Kane <getterflash at yahoo.com> 
  Sent: Tuesday, December 4, 2012 4:34 PM
  Subject: Re: [NSRCA-discussion] Serious Torque on the Nose of the Model - RESUBMITTED



  Say what?
  "a large reactionary force called gyroscopic precession"
   I feel infinitlty smarter
   Is it violent warble?
   What prop were you running????
   Mike


  From: Bob Kane <getterflash at yahoo.com>
  To: "vicenterc at comcast.net" <vicenterc at comcast.net>; General pattern discussion <nsrca-discussion at lists.nsrca.org> 
  Sent: Tuesday, December 4, 2012 7:54 AM
  Subject: Re: [NSRCA-discussion] Serious Torque on the Nose of the Model - RESUBMITTED



  The Q80 has a large diameter rotating mass, and it brings with it a large reactionary force called gyroscopic precession when it is spinning.  In laymen terms it will strongly resist changing direction in yaw or pitch.  A rear brace would help keep this force in check. 




  Bob Kane
  getterflash at yahoo.com

  From: "vicenterc at comcast.net" <vicenterc at comcast.net>
  To: General pattern discussion <nsrca-discussion at lists.nsrca.org> 
  Sent: Tuesday, December 4, 2012 8:27 AM
  Subject: Re: [NSRCA-discussion] Serious Torque on the Nose of the Model - RESUBMITTED


  I understand that a rear brace is a must for this motor.  

  Vicente "Vince" Bortone
  Sent via BlackBerry by AT&T

  -----Original Message-----
  From: "Charlie Barrera" <charliebarrera at consolidated.net>
  Sender: nsrca-discussion-bounces at lists.nsrca.org
  Date: Tue, 4 Dec 2012 07:02:47 
  To: <nsrca-discussion at lists.nsrca.org>
  Reply-To: General pattern discussion <nsrca-discussion at lists.nsrca.org>
  Subject: [NSRCA-discussion] Serious Torque on the Nose of the Model -
      RESUBMITTED

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