Typhoon 2+2

[Joe Lachowski]

Dean Pappas?? Who Dat?


>From: "Dean Pappas" <d.pappas at kodeos.com>
>Reply-To: discussion at nsrca.org
>To: <discussion at nsrca.org>
>Subject: RE: Typhoon 2+2
>Date: Thu, 30 Jan 2003 13:01:13 -0500
>
>Hello Larry,
>
>You want to preserve the location of the point that is 25% of the M.A.C.
>(mean aerodynamic chord)
>That preserves the moment arm lengths, balance point, yaw damping and
>just about any other trimming behavior.
>
>As an approximation, go half-way out on the wing panel (actually closer
>to the root) find the point at 25% of that chord, and rotate things
>around that point.
>Your 35-inch panel is actually a 38 or so inch panel , from the cl of
>the model. I am assuming about a 6" fuse width.
>The error won't matter a bunch.
>The MAC is 16.4" from the model centerline.
>The 25% point is 10.5" forward of the trailing edge, that far out.
>That's the spot that needs to stand still.
>The tip has to move forward about 30% more than the amount the root
>moves back, in order to preserve the 25% MAC position.
>
>I presented the graphical method cor calculating the MAC somne time ago
>in Flying Models, but maybe it's time for a repeat.
>
>Wing sweep contributes a dihedral effect when the wing is lifting.
>That's not the case in Knife Edge, so the
>roll coupling in KE flight should not change.
>Regards
>     Dean Pappas
>
>
>-----Original Message-----
>From: Larry Diamond [mailto:ldiamon at kimball.com]
>Sent: Thursday, January 30, 2003 11:49 AM
>To: NSRCA
>Subject: Typhoon 2+2
>
>
>
>I'm planning on scratch building a Typhoon 2+2. Just received the
>plans...
>
>In following a number of threads and talking to a few people I have some
>design questions...
>
>I plan on reducing the wing to about 975sqin and tapering the trailing
>edge forward about 1" (about 1 1/2 degrees). This is based on
>conversations of what some have found to perform better for stall spins
>and snaps.
>
>Rough estimates.
>
>Root rib - about 18
>Tip Rib - about 8
>Panel span - about 35 to 35.5.
>Airfoil - same as plans for T2+2.
>Don't plan on changing the stab unless advised to.
>
>Accounting for CG appears to have three options.
>
>1) Move the wing tube hole in the fuse back.
>2) Move the wing tube hole in the wing panels forward.
>3) Combination of the two.
>
>Which is preferred and what effects does it have on other performance?
>
>I'm at a loss for how this might effect the dihedral. Still keep the top
>of the wing flat and let the bottom fall where it may.
>
>The intent of the plan will be to fly intermediate and take me into
>advanced. I have some books on design on the way. However, I would like
>to understand the relationships from practical experience.
>
>The easy answer is to use a wing configuration that someone else has
>that is tried and proven. I would be open to this. But would still be
>interested in any thoughts for design.
>
>Perhaps this could be a good tech article for the K-Factor or possibly a
>running series.
>
>Larry
>NSRCA 3083
>AMA 5024
>


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