<DIV>The EU1 is a very interesting topic in itself. It is the aerodynamic "platypus" of pattern planes. It is the only pattern plane I know of that actually needed left engine thrust.</DIV> <DIV> </DIV> <DIV>Great flying plane it its day, though.</DIV> <DIV> </DIV> <DIV>Bob R.</DIV> <DIV><BR><BR><B><I>Dean Pappas <d.pappas@kodeos.com></I></B> wrote:</DIV> <BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">George,<BR>This is only one of several varaible involved.<BR>The side area we are most concerned with, in this discussion, is in front of the stab, though the fin/rudder counts too.<BR>The real point is that no serious Pattern designer would start out to put the stab on the very top, or very bottom, of the fuse.<BR>You might end up there, though!<BR>Proof is found in the common mod to the EU1-A: dropping the stab to the very bottom of the plane fixed a vertyical canopy-pull, which doesn't make sense in the
context of this discussion. Sometimes, you gotta cut and try.<BR><BR>Dean<BR><BR>Dean Pappas<BR>Sr. Design Engineer<BR>Kodeos Communications<BR>111 Corporate Blvd.<BR>South Plainfield, N.J. 07080<BR>(908) 222-7817 phone<BR>(908) 222-2392 fax<BR>d.pappas@kodeos.com<BR><BR><BR>-----Original Message-----<BR>From: nsrca-discussion-bounces@lists.nsrca.org<BR>[mailto:nsrca-discussion-bounces@lists.nsrca.org]On Behalf Of George<BR>Kennie<BR>Sent: Wednesday, February 01, 2006 11:46 AM<BR>To: nsrca-discussion@lists.nsrca.org<BR>Subject: [NSRCA-discussion] pitch<BR><BR><BR>I'm having some problems with this one. Nothing serious, mind you,<BR>but just a little confusion.<BR>If we take this stab/fuse joint pressure build up to be causative,<BR>then it should logically follow that in order to achieve<BR>equilibrium, the rudder area above and below the stab should be<BR>equal.<BR>Then if we take the Stick, everything (area) is above the stab,<BR>which lends credence to the hypothesis, but if we
go back to the<BR>Cap, the area is now closer to equal, but probably weighted slightly<BR>in one direction or the other, but closer to the equality that we<BR>are seeking, and yet the reaction is just as violent except in the<BR>opposing direction.<BR>Therefore, we must assume that the point of equilibrium is at some<BR>point between the two locations.<BR>With our thoeretical airplane with it's adjustable stab, we end up<BR>determining that indeed the point of equilibrium appears to be at a<BR>much lower point (relative to the rudder area) than we would have<BR>originally anticipated. So we, at this point find ourselves doing<BR>some serious head scratchin'.<BR>On the other hand, if we take the two airframes together and analize<BR>the force arrangements we find that they are basically inverted<BR>mirror images of one another,i.e., Stick, ........wing on top, stab<BR>on bottom. Cap, wing on bottom, stab on top. And yet the rudder area<BR>intersect points are definitely not mirror
images.For that to be the<BR>case, the Cap would have to be a T-Tail. Something doesn't jibe!<BR>Here we have the Cap with close to a balanced area scenario and yet<BR>we have the dreaded pitch to the belly. If we now turn the Cap<BR>upside down and cut off the canopy and glue it to the belly<BR>pretending that the belly is now the top and fly the airplane it now<BR>pitches to the canopy( new top, but still really to the belly). The<BR>problem with this scenario is that, in this inverted position the<BR>Cap's fin and rudder become equivalent to the biggest sub-fin,<BR>ventral, strake, whatever you want to call it and yet it doesn't<BR>correct the pitching problem.<BR>I have strong feelings that the dynamics are located in a different<BR>area and would contend that a poorly designed force arrangement<BR>cannot be corrected with a band-aid approach.<BR>This is not intended to raise anybody's hackles, just my two cents.<BR>G.<BR><BR><BR><BR><BR><BR>Since were still guessing at cause of
pull to top in knife edge,<BR>Here is my Suspect -<BR>Stab is on bottom of fuse- true with this design?<BR>When rudder is applied, air pressure builds at intersection of fuse<BR>& Fin,<BR>with the top of the stab. Pressure on top of stab creates a nose up<BR>condition. There is no equivalent pressure on bottom, cause there<BR>is little or no fuse and fin.<BR><BR>If that is the cause, adding a strake to bottom might improve it.<BR><BR>Later, Ron Lockhart<BR><BR><BR>_______________________________________________<BR>NSRCA-discussion mailing list<BR>NSRCA-discussion@lists.nsrca.org<BR>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion<BR><BR>_______________________________________________<BR>NSRCA-discussion mailing list<BR>NSRCA-discussion@lists.nsrca.org<BR>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion<BR></BLOCKQUOTE> <DIV><BR></DIV>