[NSRCA-discussion] Fw: Serious Torque on the Nose of the Model- RESUBMITTED
Bob Kane
getterflash at yahoo.com
Wed Dec 5 08:38:25 AKST 2012
Great observations. I am curious about the numbers myself, maybe in my spare time (ha!) I'll pull out my old physics books and crunch some numbers.
Bob Kane
getterflash at yahoo.com
________________________________
From: ehaury <ejhaury at comcast.net>
To: mike mueller <mikemueller at f3aunlimited.com>; General pattern discussion <nsrca-discussion at lists.nsrca.org>
Sent: Wednesday, December 5, 2012 11:02 AM
Subject: Re: [NSRCA-discussion] Fw: Serious Torque on the Nose of the Model- RESUBMITTED
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
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