[NSRCA-discussion] Trimming question

[ronlock at comcast.net]

Since were still guessing at cause of pull to top in knife edge,
Here is my Suspect -
Stab is on bottom of fuse- true with this design?
When rudder is applied, air pressure builds at intersection of fuse & Fin, 
with the top of the stab.  Pressure on top of stab creates a nose up condition.   There is no equivalent pressure on bottom, cause there is little or no fuse and fin.

If that is the cause, adding a strake to bottom might improve it.

Later, Ron Lockhart

-------------- Original message -------------- 
From: "John Ferrell" <johnferrell at earthlink.net> 

> My Guess: 
> The sum of the drag vectors is well above the vertical CG. You MIGHT be able 
> to help the condition with really big wheels generating some drag down low. 
> Its anybody's guess what the turbulance might trigger. 
> 
> The wing is not lifting in knife edge, but it is still draggin'. 
> 
> John Ferrell 
> http://DixieNC.US 
> 
> ----- Original Message ----- 
> From: "John Pavlick" 
> To: "NSRCA Discussion" 
> Sent: Friday, January 27, 2006 11:31 PM 
> Subject: [NSRCA-discussion] Trimming question 
> 
> 
> > Ok here's a good one. The owner of the L.H.S. asked me what I thought 
> > about 
> > this and I couldn't come up with a good answer. He has a Hangar 9 Ugly 
> > Stik - the real big one. I can't remember exactly what it's called. Guess 
> > it 
> > has a gas motor in it. It's big. He says he has it trimmed so it will fly 
> > inverted with just a very slight bit of down elevator (almost none). Ok, 
> > so 
> > it's not nose heavy, maybe even a little tail heavy. Now, when he flies it 
> > knife edge (either side) it pulls severely to the canopy. I mean like it 
> > will fly a complete circle. It needs almost 3/4 down elevator to fly 
> > straight. It's beyond a mix - fix. He also says that it has a bit of roll 
> > couple when flying level (not knife edge) but it doesn't pitch severely up 
> > or down under these conditions. Any thoughts? I guess you can rule out 
> > C.G. 
> > because if anything it should pull to the belly considering how it's 
> > trimmed 
> > to fly level upright and inverted. I haven't flown it so I can't add too 
> > much more. He builds OK so I don't think there's anything way out of 
> > alignment, but again I haven't seen it yet so maybe there is. What should 
> > I 
> > look for if I get my hands on it to try and help him? 
> > 
> > John Pavlick 
> > http://www.idseng.com 
> > 
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