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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>I agree with Chris. I’ve personally had thousands of flights with nose mounted motors with rear supports and never had so much as a hint of failure. If you count all the flights I’ve seen Andrew fly with his nose mounted, rear supported motors as well as countless others at the practice field and on the contest trail, the number probably reaches into the tens of thousands. <o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>The only time I’ve ever witnessed a catastrophic motor induced fuselage failure was while I was judging an FAI pilot flying an Axi-equipped Smaragd a few years back. Following a turnaround, there was a short, deep, rumbling sound that sounded a little like flutter with heavy bass followed by the departure of the motor and a significant section of the nose of the fuse. The motor was nose mounted and had no rear support. <o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>My best guess, and it is just a guess, was that the prop arc coupled with the forces of the looping turnaround, set up a harmonic, or flutter if you will, that the fuse couldn’t contain. The rumble was very brief before it came apart. <o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>I have no engineering data to report, just practical experience. A nose mounted motor without a rear support is a disaster about to happen. As Chris said, it’s just a matter of when.<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'>Verne Koester<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> nsrca-discussion-bounces@lists.nsrca.org [mailto:nsrca-discussion-bounces@lists.nsrca.org] <b>On Behalf Of </b>Chris<br><b>Sent:</b> Wednesday, December 05, 2012 12:50 PM<br><b>To:</b> Bob Kane; General pattern discussion<br><b>Subject:</b> Re: [NSRCA-discussion] Fw: Serious Torque on the Nose of the Model- RESUBMITTED<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>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.<br><br>Chris<o:p></o:p></p><div><p class=MsoNormal>On 12/5/2012 12:38 PM, Bob Kane wrote:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><div><p class=MsoNormal style='background:white'>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. <o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal style='background:white'>Bob Kane<br><a href="mailto:getterflash@yahoo.com">getterflash@yahoo.com</a><o:p></o:p></p></div><div><div><div><div class=MsoNormal align=center style='text-align:center;background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'><hr size=1 width="100%" align=center></span></div><p class=MsoNormal style='background:white'><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> ehaury <a href="mailto:ejhaury@comcast.net"><ejhaury@comcast.net></a><br><b>To:</b> mike mueller <a href="mailto:mikemueller@f3aunlimited.com"><mikemueller@f3aunlimited.com></a>; General pattern discussion <a href="mailto:nsrca-discussion@lists.nsrca.org"><nsrca-discussion@lists.nsrca.org></a> <br><b>Sent:</b> Wednesday, December 5, 2012 11:02 AM<br><b>Subject:</b> Re: [NSRCA-discussion] Fw: Serious Torque on the Nose of the Model- RESUBMITTED</span><o:p></o:p></p></div><p class=MsoNormal style='background:white'><o:p> </o:p></p><div id=yiv732353877><div><div><p class=MsoNormal style='background:white'><span style='font-family:"Arial","sans-serif"'>I don't know what caused Charlie's failure, we've discussed possibilities - obviously forces occurred that were beyond what the structure could handle.</span><o:p></o:p></p></div><div><p class=MsoNormal style='background:white'> <o:p></o:p></p></div><div><p class=MsoNormal style='background:white'><span style='font-family:"Arial","sans-serif"'>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.</span><o:p></o:p></p></div><div><p class=MsoNormal style='background:white'> <o:p></o:p></p></div><div><p class=MsoNormal style='background:white'><span style='font-family:"Arial","sans-serif"'>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.)</span><o:p></o:p></p></div><div><p class=MsoNormal style='background:white'> <o:p></o:p></p></div><div><p class=MsoNormal style='background:white'><span style='font-family:"Arial","sans-serif"'>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.</span><o:p></o:p></p></div><div><p class=MsoNormal style='background:white'> <o:p></o:p></p></div><div><p class=MsoNormal style='background:white'><span style='font-family:"Arial","sans-serif"'>Essentially something slightly different that adds to the learning curve, hopefully Charlie's experience and these discussions will prevent further occurrences.</span><o:p></o:p></p></div><div><p class=MsoNormal style='background:white'> <o:p></o:p></p></div><div><p class=MsoNormal style='background:white'><span style='font-family:"Arial","sans-serif"'>Earl</span><o:p></o:p></p></div><blockquote style='border:none;border-left:solid black 1.5pt;padding:0in 0in 0in 4.0pt;margin-left:3.75pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>----- Original Message ----- <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:#E4E4E4'><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> <a href="mailto:mikemueller@f3aunlimited.com" target="_blank" title="mikemueller@f3aunlimited.com">mike mueller</a> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>To:</span></b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> <a href="mailto:getterflash@yahoo.com" target="_blank" title="getterflash@yahoo.com">Bob Kane</a> ; <a href="mailto:nsrca-discussion@lists.nsrca.org" target="_blank" title="nsrca-discussion@lists.nsrca.org">General pattern discussion</a> <o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Sent:</span></b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> Wednesday, December 05, 2012 8:26 AM<o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Subject:</span></b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> Re: [NSRCA-discussion] Fw: Serious Torque on the Nose of the Model- RESUBMITTED<o:p></o:p></span></p></div><div><p class=MsoNormal style='background:white'><o:p> </o:p></p></div><div><div><p class=MsoNormal style='background:white'>Very cool video. I've learned a lot of neat things watching Youtube video's. Thanks Bob<o:p></o:p></p></div><div><p class=MsoNormal style='background:white'><o:p> </o:p></p></div><div><div><div><p class=MsoNormal style='background:white'><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> Bob Kane <<a href="mailto:getterflash@yahoo.com" target="_blank">getterflash@yahoo.com</a>><br><b>To:</b> Generalpatterndiscussion <<a href="mailto:nsrca-discussion@lists.nsrca.org" target="_blank">nsrca-discussion@lists.nsrca.org</a>> <br><b>Sent:</b> Wednesday, December 5, 2012 7:07 AM<br><b>Subject:</b> [NSRCA-discussion] Fw: Serious Torque on the Nose of the Model - RESUBMITTED</span><o:p></o:p></p></div><p class=MsoNormal style='background:white'><o:p> </o:p></p><div id=yiv732353877><div><div><div><p class=MsoNormal style='background:white'>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 . .. . <o:p></o:p></p></div><div><div><div id=yiv732353877><div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><a href="http://www.youtube.com/watch?v=ty9QSiVC2g0">http://www.youtube.com/watch?v=ty9QSiVC2g0</a><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal style='background:white'> <o:p></o:p></p></div><div><p class=MsoNormal style='background:white'>Bob Kane<br><a href="mailto:getterflash@yahoo.com">getterflash@yahoo.com</a><o:p></o:p></p></div><div><div><div><p class=MsoNormal style='background:white'><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> mike mueller <a href="mailto:mikemueller@f3aunlimited.com"><mikemueller@f3aunlimited.com></a><br><b>To:</b> Bob Kane <a href="mailto:getterflash@yahoo.com"><getterflash@yahoo.com></a> <br><b>Sent:</b> Tuesday, December 4, 2012 4:34 PM<br><b>Subject:</b> Re: [NSRCA-discussion] Serious Torque on the Nose of the Model - RESUBMITTED</span><o:p></o:p></p></div><p class=MsoNormal style='background:white'><o:p> </o:p></p><div id=yiv732353877><div><div><div><p class=MsoNormal style='background:white'>Say what?<o:p></o:p></p></div><div><p class=MsoNormal>"a large reactionary force called gyroscopic precession"<o:p></o:p></p></div><div><p class=MsoNormal> I feel infinitlty smarter<o:p></o:p></p></div><div><p class=MsoNormal> Is it violent warble?<o:p></o:p></p></div><div><p class=MsoNormal> What prop were you running????<o:p></o:p></p></div><div><p class=MsoNormal> Mike<o:p></o:p></p></div><div><p class=MsoNormal style='background:white'><o:p> </o:p></p></div><div><div><div><p class=MsoNormal style='background:white'><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> Bob Kane <a href="mailto:getterflash@yahoo.com"><getterflash@yahoo.com></a><br><b>To:</b> <a href="mailto:vicenterc@comcast.net">"vicenterc@comcast.net"</a> <a href="mailto:vicenterc@comcast.net"><vicenterc@comcast.net></a>; General pattern discussion <a href="mailto:nsrca-discussion@lists.nsrca.org"><nsrca-discussion@lists.nsrca.org></a> <br><b>Sent:</b> Tuesday, December 4, 2012 7:54 AM<br><b>Subject:</b> Re: [NSRCA-discussion] Serious Torque on the Nose of the Model - RESUBMITTED</span><o:p></o:p></p></div><p class=MsoNormal style='background:white'><o:p> </o:p></p><div id=yiv732353877><div><div><div><p class=MsoNormal style='background:white'><span style='font-family:"Times","serif"'>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. </span><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><br> <o:p></o:p></p></div><div><p class=MsoNormal style='background:white'>Bob Kane<br><a href="mailto:getterflash@yahoo.com">getterflash@yahoo.com</a><o:p></o:p></p></div><div><div><div><p class=MsoNormal style='background:white'><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> <a href="mailto:vicenterc@comcast.net">"vicenterc@comcast.net"</a> <a href="mailto:vicenterc@comcast.net"><vicenterc@comcast.net></a><br><b>To:</b> General pattern discussion <a href="mailto:nsrca-discussion@lists.nsrca.org"><nsrca-discussion@lists.nsrca.org></a> <br><b>Sent:</b> Tuesday, December 4, 2012 8:27 AM<br><b>Subject:</b> Re: [NSRCA-discussion] Serious Torque on the Nose of the Model - RESUBMITTED</span><o:p></o:p></p></div><p class=MsoNormal style='margin-bottom:12.0pt;background:white'><br>I understand that a rear brace is a must for this motor. <br><br>Vicente "Vince" Bortone<br>Sent via BlackBerry by AT&T<br><br>-----Original Message-----<br>From: "Charlie Barrera" <<a href="mailto:charliebarrera@consolidated.net" target="_blank">charliebarrera@consolidated.net</a>><br>Sender: <a href="mailto:nsrca-discussion-bounces@lists.nsrca.org" target="_blank">nsrca-discussion-bounces@lists.nsrca.org</a><br>Date: Tue, 4 Dec 2012 07:02:47 <br>To: <<a href="mailto:nsrca-discussion@lists.nsrca.org" target="_blank">nsrca-discussion@lists.nsrca.org</a>><br>Reply-To: General pattern discussion <<a href="mailto:nsrca-discussion@lists.nsrca.org" target="_blank">nsrca-discussion@lists.nsrca.org</a>><br>Subject: [NSRCA-discussion] Serious Torque on the Nose of the Model -<br> RESUBMITTED<br><br>_______________________________________________<br>NSRCA-discussion mailing list<br><a href="mailto:NSRCA-discussion@lists.nsrca.org" target="_blank">NSRCA-discussion@lists.nsrca.org</a><br><a href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a><br>_______________________________________________<br>NSRCA-discussion mailing list<br><a href="mailto:NSRCA-discussion@lists.nsrca.org" target="_blank">NSRCA-discussion@lists.nsrca.org</a><br><a href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion" target="_blank">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a><br><br><o:p></o:p></p></div></div></div></div></div><p class=MsoNormal style='margin-bottom:12.0pt;background:white'><br>_______________________________________________<br>NSRCA-discussion mailing list<br><a href="mailto:NSRCA-discussion@lists.nsrca.org" target="_blank">NSRCA-discussion@lists.nsrca.org</a><br><a href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion" target="_blank">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a><o:p></o:p></p></div></div></div></div></div><p class=MsoNormal style='margin-bottom:12.0pt;background:white'><o:p> </o:p></p></div></div></div></div><p class=MsoNormal style='margin-bottom:12.0pt;background:white'><o:p> </o:p></p></div></div></div></div></div><p class=MsoNormal style='margin-bottom:12.0pt;background:white'><br>_______________________________________________<br>NSRCA-discussion mailing list<br><a href="mailto:NSRCA-discussion@lists.nsrca.org" target="_blank">NSRCA-discussion@lists.nsrca.org</a><br><a href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion" target="_blank">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a><o:p></o:p></p></div></div></div><div class=MsoNormal align=center style='text-align:center;background:white'><hr size=3 width="100%" align=center></div><p class=MsoNormal style='background:white'>_______________________________________________<br>NSRCA-discussion mailing list<br><a href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</a><br><a href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a> <o:p></o:p></p><div class=MsoNormal align=center style='text-align:center;background:white'><hr size=3 width="100%" align=center></div><p class=MsoNormal style='background:white'>No virus found in this message.<br>Checked by AVG - <a href="http://www.avg.com/" target="_blank">www.avg.com</a><br>Version: 2012.0.2221 / Virus Database: 2634/5437 - Release Date: 12/04/12<o:p></o:p></p></blockquote></div></div><p class=MsoNormal style='margin-bottom:12.0pt;background:white'><br>_______________________________________________<br>NSRCA-discussion mailing list<br><a href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</a><br><a href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion" target="_blank">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a><o:p></o:p></p></div></div></div><p class=MsoNormal><br><br><br><o:p></o:p></p><pre>_______________________________________________<o:p></o:p></pre><pre>NSRCA-discussion mailing list<o:p></o:p></pre><pre><a href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</a><o:p></o:p></pre><pre><a href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a><o:p></o:p></pre></blockquote><p class=MsoNormal><o:p> </o:p></p></div></body></html>