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

Chris cjm767driver at hotmail.com
Wed Dec 5 08:50:28 AKST 2012 

Early in the electric transition, many of us found out the hard way that 
nose mounted outrunners without a rear support would lead to structural 
failures with nearly 100% certainty.  My nose mounted Genesis lasted 1 
1/2 flights before failure.  Others had many more flights but even the 
best cases I know of had nose structure stresses and cracking due to the 
unsupported nose mounting.  Jerry Budd and I did a lot of testing and 
posting about this issue back in 2006 or 2007.  Newer designs have 
reinforced noses which help but bottom line, don't nose mount an 
electric motor without rear support. It "might" last 1 or 500 flights 
but 501 won't be as successful.

Chris

On 12/5/2012 12:38 PM, Bob Kane wrote:
> 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 <mailto:mikemueller at f3aunlimited.com>
>     *To:* Bob Kane <mailto:getterflash at yahoo.com> ; General pattern
>     discussion <mailto:nsrca-discussion at lists.nsrca.org>
>     *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
>     <mailto:getterflash at yahoo.com>>
>     *To:* Generalpatterndiscussion <nsrca-discussion at lists.nsrca.org
>     <mailto: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
>     <mailto:charliebarrera at consolidated.net>>
>     Sender: nsrca-discussion-bounces at lists.nsrca.org
>     <mailto:nsrca-discussion-bounces at lists.nsrca.org>
>     Date: Tue, 4 Dec 2012 07:02:47
>     To: <nsrca-discussion at lists.nsrca.org
>     <mailto:nsrca-discussion at lists.nsrca.org>>
>     Reply-To: General pattern discussion
>     <nsrca-discussion at lists.nsrca.org
>     <mailto:nsrca-discussion at lists.nsrca.org>>
>     Subject: [NSRCA-discussion] Serious Torque on the Nose of the Model -
>     RESUBMITTED
>
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