[NSRCA-discussion] Fwd: RE: Design Question

Tue Nov 10 15:56:03 AKST 2009

Thanks, that leads me to believe that it's not as critical as I thought. I
guess if both the wing and stab are adjustable we can effectively change the
in-flight vertical offset. I have about decided on 3/4" for the first
airplane.
Tom, I do use CAD and the changes are relatively easy. These parts are all
'subparts' and easily relocated and revised. Any changes made after the
initial plot to paper will need to be filed as a revision in-order to keep
track of what I am building, revising and changing during or after the next
flying season.
Jim

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Matthew
Frederick
Sent: Tuesday, November 10, 2009 4:05 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Fwd: RE: Design Question

I overheard Nat at a recent contest stating he felt the horizontal stab
placement relative to the wing chord is fairly irrelevant as long as it's no
further than 1.5 inches from the line, and anything beyond that will cause
undesirable results. I'm not saying I agree or disagree with that
assessment, just take it for what it's worth. I feel he over-thinks things
at times, but the true test is in the trimming and flying anyway.

Matt
----- Original Message -----
From: "Koenig, Tom" <Tom.Koenig at actewagl.com.au>
To: "'General pattern discussion'" <nsrca-discussion at lists.nsrca.org>
Sent: Tuesday, November 10, 2009 3:13 PM
Subject: Re: [NSRCA-discussion] Fwd: RE: Design Question

> Hi Jim and all,
>
> Jim.....enjoy those long winters, have a hot cup of coffee....and realy, I
> mean really, think about what Bryan tells you. It is a brain twister and
> can be confusing. But...he is right in everything he tells you. I realise
> there are people out there who do not agree with Bryan, and that is fine,
> but my advice is to have a read of his article-if only for interest.
>
> If I had the time, and my ability to express myself were better-I would
> try to explain some of my design ideas. But I simply suck at that-hence my
> initial response, just go for it.
>
> Another genius to ask(besides Bryan) would be Nat Penton...he will also
> make your head spin! A very learn'ed man indeed.
>
> Draw a line on a sheet of paper as your Datum, mark out 2 meters and go
> for it. Better still, use some CAD package.
>
> PS. Make it pretty-or you wont want to fly it!! Also-keep us informed how
> you are going. I certainly am interested in your project, maybe others are
> too.
>
> Tom
>
>
>
>
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
> shinden1 at cox.net
> Sent: Wednesday, 11 November 2009 7:48 AM
> To: General pattern discussion
> Subject: Re: [NSRCA-discussion] Fwd: RE: Design Question
>
> Ok
> Bryan
> ---- shinden1 at cox.net wrote:
>>
>> > From: "J N Hiller" <jnhiller at earthlink.net>
>> > To: <shinden1 at cox.net>
>> > Subject: RE: [NSRCA-discussion] Design Question
>> > Date: Tue, 10 Nov 2009 09:51:44 -0800
>> >
>> > Bryan, I find it hard to believe that vertical wing placement doesn't
>> > affect pitch trim. The wing especially a thick one contributes
>> > significantly to total drag and any offset between the center of drag
>> > and center of thrust would create a rotational moment that would need
>> > to be balanced with H-stab / elevator trim. Maybe it's insignificant
>> > compared to other factors. This is what I'm trying to understand.
>> > Yes CG is a significant contributor. I've been able to change vertical
>> > pitch by changing the CG and wing incidence, forcing a H-stab /
>> > elevator trim change. CG placement is a whole different issue as is
>> > weight in the extremities such as wing tips, nose and tail.
>> > Thanks.
>> > I'm really interested in this aspect of pattern, good thing, winters
>> > are long here.
>> > Jim
>> >
>> > -----Original Message-----
>> > From: shinden1 at cox.net [mailto:shinden1 at cox.net]
>> > Sent: Monday, November 09, 2009 7:14 PM
>> > To: General pattern discussion
>> > Cc: J N Hiller
>> > 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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