[NSRCA-discussion] Design Question

[patterndude at tx.rr.com]

Rereading I see I kindof answered the wrong question. I was thinking about the vertical place of the stab, not the wing. Add what Bryan said to what I said with an addition. Note we don't want the eng,wing,stab all on the same line. There is stability in biased surfaces
Lance
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-----Original Message-----
From: <shinden1 at cox.net>
Date: Mon, 9 Nov 2009 22:13:56 
To: General pattern discussion<nsrca-discussion at lists.nsrca.org>
Subject: Re: [NSRCA-discussion] Design Question

Hi Jim
The vertical wing placement has no effect on pitch trim,,NONE !
what does is,the incidence and C/g. Don`t even worry about it. 
However it will effect  Dihedra you will need to move the wing after the test flights. or rebuild a new one with the right dihedral or, Mix it out.
Rudder angles ,sweep, or position ,has a tiny effect ,so little it`s not worth worrying about .draw something that looks good.
Just build your airplane and adjust to what it does not do well. 
your not going to hit it on the first try,but the effort will be worth the Learning and enjoyment, in a self designed model.
There are so many dynamics involved in designing your first airplane 
you cant possibly think of them all on the first attempt.
just  have fun and build a light pretty model.
Bryan
---- J N Hiller <jnhiller at earthlink.net> wrote: 
> Thanks Lance. I don't want to stray too far from proven relationships but
> understand there are many variables rendering each design different.
> I presently have the wing located 1/2" below a centerline through the H-stab
> and engine centerline. The stab is about 1/2" above the tail tube centerline
> and positioned about 1/4 the height of the V-stab.
> Both the wing and stab will be adjustable and previsions are included for
> changing thrust angles. Tweaking these angles should effectively change the
> flying height of the tail but the wing offset remains about the same.
> Other than changing the vertical center of drag what are the pros and cons
> associated with positioning the wing higher or lower. I'm thinking the
> vertical center of drag relative to the thrust line can contribute
> significantly to pitch trim. Is it a major influence?
> Before beginning to cut parts it occurred to me that the design /
> construction detail offers considerable leeway in vertical wing placement,
> maybe as much as an inch higher or lower from the -1/2 presently planned and
> changing the wing location later will require major surgery.
> I guess what I'm really looking for is more understanding of the effect
> vertical wing placement has on pitch trim. I guess I asked the wrong
> question. Any thoughts on this will be helpful.
> Thanks
> Jim
> 
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of
> patterndude at tx.rr.com
> Sent: Monday, November 09, 2009 2:38 PM
> To: General pattern discussion
> Subject: Re: [NSRCA-discussion] Design Question
> 
> That's all?  There a number of design issues we face in pattern where
> there's little documentation readily available. This is one, KE flight is
> another, wing incidence and engine thrustline effects in 4 axis flight is
> another. The more I think about it the more I think of.
>   There's no one answer and anything between the chordline and thrustline
> can be made to work by changing rudder shape and incidence. I settled on a
> quarter inch above the chordline and then adjusted the rudder to allow a
> trim incidence near zero so inverted flight is more effortless.
> 
> Lance
> AeroSlave
> Sent via BlackBerry by AT&T
> 
> -----Original Message-----
> From: "J N Hiller" <jnhiller at earthlink.net>
> Date: Mon, 9 Nov 2009 09:36:13
> To: NSRCA Mailing List<nsrca-discussion at lists.nsrca.org>
> Subject: [NSRCA-discussion] Design Question
> 
> Hello all.
> Here's a topic for discussion that I'm personally very interested in and may
> be of interest to others.
> I'm working up a new pattern design and would appreciate comments regarding
> the vertical placement of the wing and thrust line relative to the stab
> centerline.
> I not only would like to know what the vertical offset is on modern pattern
> designs but how the vertical location affects flight trim, and why?
> Thanks all.
> Jim Hiller
> 
> 
> 
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