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<div>If you look at my Dad's Phoenix designs, you will see that as the series went on, he went to less and less sweep. The Phoenix 3, of which only one was built, had the most, even more than the Phoenix 1, and he quickly abandoned that sweep. The last in the series, the 9 and 10, had only leading edge sweep with a straight trailing edge. The theory at the time was that sweep added dihedral effect in looping maneuvers and made it more stable. RVP can answer whether there is anything to this argument or not.</div>
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<div>I've never heard him talk about the coupling phenomena during loops that Dave mentions, and I haven't noticed it when flying my Phoenix 6 or 7. Of course those older designs with the short tail moments by today's standards are harder (IMHO) to fly well in general, and I only dig them out for one BPA event a year, so I really haven't looked for it. I do know that my Dad specifically designed in pro-roll coupling in the Phoenix 1 in case the aileron servo went out so he had a chance of landing it on rudder! He mentioned that fact in the article for RCM. Of course, the Phoenix 1 was designed when reeds were king, before digital proportional, and equipment was less than robust. It was a radical design for its day, but it wasn't the first with swept wings. The series was arguably one of the most successful in pattern during the 60's and 70's, so something was right with the design.</div>
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<div style="clear: both;"><font color="black" face="Arial, Helvetica, sans-serif"><font color="black" face="arial"><span class="Apple-style-span" style="font-size: medium;">Jon</span></font></font></div>
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<div style="color: black; font-family: arial,helvetica; font-size: 10pt;">-----Original Message-----<br>
From: Dave Lockhart <DaveL322@comcast.net><br>
To: 'General pattern discussion' <nsrca-discussion@lists.nsrca.org><br>
Sent: Mon, Dec 9, 2013 8:04 am<br>
Subject: Re: [NSRCA-discussion] Wing Sweep Angle?<br>
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<div class="MsoNormal"><span style="font-family:; font-size: 11pt;">Jon Lowe might jump in at some point……but I recall a discussion years ago related to Don Lowe’s Phoenix series. I don’t recall the exact numbers, but at a certain amount of sweep, there was minimal (if any) benefit for pattern flying, and even if the correct rudder response (no coupling) was maintained, there was an increased propensity for pro-roll when the wing was loaded (ie, looping) with increased wing sweep. I know my Dad’s Phoenix 6 definitely exhibited that tendency – no roll coupling in Knife Edge, but minor pro-roll coupling during loops.</span></div>
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<div class="MsoNormal"><span style="font-family:; font-size: 11pt;">Regards,</span></div>
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<div class="MsoNormal"><span style="font-family:; font-size: 11pt;">Dave</span></div>
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<div class="MsoNormal"><b><span style="font-family:; font-size: 10pt;">From:</span></b><span style="font-family:; font-size: 10pt;"> <a href="mailto:nsrca-discussion-bounces@lists.nsrca.org">nsrca-discussion-bounces@lists.nsrca.org</a> [<a href="mailto:nsrca-discussion-bounces@lists.nsrca.org?">mailto:nsrca-discussion-bounces@lists.nsrca.org</a>] <b>On Behalf Of </b><a href="mailto:rcmaster199@aol.com">rcmaster199@aol.com</a><br>
<b>Sent:</b> Sunday, December 08, 2013 11:52 PM<br>
<b>To:</b> <a href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</a><br>
<b>Subject:</b> Re: [NSRCA-discussion] Wing Sweep Angle?</span></div>
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<div class="MsoNormal"><span style="font-family:; font-size: 10pt;">Jim,</span></div>
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<div class="MsoNormal"><span style="font-family:; font-size: 10pt;">The root and tip chords do not have ACs per se, but you know that already. The AC of a wing panel is located at 25% MAC and everything I've read on the subject seems in agreement, at least for full scale, so I use that value for my models. I think that's what Smith is alluding to</span></div>
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<div class="MsoNormal"><span style="font-family:; font-size: 10pt;">The actual angle I think is relative to the fuse CL...So if the wing is rectangular, sweep is considered zero by convention (I think) (Ron correct me if there is no convention on this). If sweep is aft, the angle should be straight forward to measure or calculate. If sweep is fore, same thing except the sign is reversed.</span></div>
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<div class="MsoNormal"><span style="font-family:; font-size: 10pt;">For the model wings I use (much higher root to tip ratios than every one else uses), sweep at 25% chord is about 20 degrees to the rear. I haven't found it excessive or insufficient. It doesn't affect the parameters I use for wing vertical location on the fuse (given a specific dihedral angle). This has been tested on 6 original designs so far over the years with somewhat variable sweep angle (a few degrees, maybe as much as 5 degrees delta). The dihedral effect delta has been nil. </span></div>
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<div class="MsoNormal"><span style="font-family:; font-size: 10pt;">regads</span></div>
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<div class="MsoNormal"><span style="font-family:; font-size: 10pt;">Matt</span></div>
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<div class="MsoNormal" style="margin-bottom: 12pt;"><span style="font-family:; font-size: 10pt;">-----Original Message-----<br>
From: J N Hiller <<a href="mailto:jnhiller@earthlink.net">jnhiller@earthlink.net</a>><br>
To: General pattern discussion <<a href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</a>><br>
Sent: Sun, Dec 8, 2013 8:04 pm<br>
Subject: Re: [NSRCA-discussion] Wing Sweep Angle?</span></div>
<div id="AOLMsgPart_0_c06ae939-25c5-422c-aad8-5b16c2ef6cb6"><pre style="background: white;"><tt><span style="color: black;">Thank you that's exactly what I wanted to know. I've changed it on different</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">airplanes and wanted to use a 'correct' standard reference when listing</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">design parameters. I'm finding some sweep is good more isn't, in my opinion.</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">Jim</span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;">-----Original Message-----</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">From: <a href="mailto:nsrca-discussion-bounces@lists.nsrca.org">nsrca-discussion-bounces@lists.nsrca.org</a></span></tt></pre><pre style="background: white;"><tt><span style="color: black;">[<a href="mailto:nsrca-discussion-bounces@lists.nsrca.org]On?">mailto:nsrca-discussion-bounces@lists.nsrca.org]On</a> Behalf Of Ryan Smith</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">Sent: Sunday, December 08, 2013 2:21 PM</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">To: 'General pattern discussion'</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">Subject: Re: [NSRCA-discussion] Wing Sweep Angle?</span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;">Hi Jim,</span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;">I was always taught to use the aerodynamic center of the root and tip, and</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">project a line down the span of the wing across these two points. It's</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">pretty close to 25% generally; it may be a few percent off, but for the</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">purposes of calculation, it's really close. There are enough variables in</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">the scheme of things to render that exact enough for our purposes.</span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;">I hope this helps.</span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;">Best regards,</span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;">Ryan</span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;">-----Original Message-----</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">From: <a href="mailto:nsrca-discussion-bounces@lists.nsrca.org">nsrca-discussion-bounces@lists.nsrca.org</a></span></tt></pre><pre style="background: white;"><tt><span style="color: black;">[<a href="mailto:nsrca-discussion-bounces@lists.nsrca.org?">mailto:nsrca-discussion-bounces@lists.nsrca.org</a>] On Behalf Of J N Hiller</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">Sent: Sunday, December 08, 2013 4:17 PM</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">To: NSRCA Mailing List</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">Subject: [NSRCA-discussion] Wing Sweep Angle?</span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;">Question!</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">How dose one measure wing sweep angle on tapered wing panels? Is it located</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">as a percentage of cord?</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">Jim Hiller</span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;">_______________________________________________</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">NSRCA-discussion mailing list</span></tt></pre><pre style="background: white;"><tt><span style="color: black;"><a href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</a></span></tt></pre><pre style="background: white;"><tt><span style="color: black;"><a href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion" target="_blank">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a></span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;">_______________________________________________</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">NSRCA-discussion mailing list</span></tt></pre><pre style="background: white;"><tt><span style="color: black;"><a href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</a></span></tt></pre><pre style="background: white;"><tt><span style="color: black;"><a href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion" target="_blank">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a></span></tt></pre><pre style="background: white;"><tt><span style="color: black;"> </span></tt></pre><pre style="background: white;"><tt><span style="color: black;">_______________________________________________</span></tt></pre><pre style="background: white;"><tt><span style="color: black;">NSRCA-discussion mailing list</span></tt></pre><pre style="background: white;"><tt><span style="color: black;"><a href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</a></span></tt></pre><pre style="background: white;"><tt><span style="color: black;"><a href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion" target="_blank">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a></span></tt></pre></div>
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