[NSRCA-discussion] Guys I need help...

Wed Dec 27 14:27:06 AKST 2006

Ryan is right.
----- Original Message ----- 
From: "Ryan Smith" <smaragdz at bellsouth.net>
To: "'NSRCA Mailing List'" <nsrca-discussion at lists.nsrca.org>
Sent: Wednesday, December 27, 2006 5:16 PM
Subject: Re: [NSRCA-discussion] Guys I need help...


> John,
>
> I think it's best to deal with the man that designed the airplane himself 
> in
> a situation like this. Dave's e-mail is dtg at triad.rr.com . If you prefer 
> to
> talk to him via telephone, let me know and I'll give you his number. He
> would be more than happy to help you out with whatever you may need. I'm
> flying with him tomorrow and I'll let him know of your difficulties.
>
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Randall
> Bearden
> Sent: Wednesday, December 27, 2006 5:36 PM
> To: NSRCA Mailing List
> Subject: Re: [NSRCA-discussion] Guys I need help...
>
> On 12/27/06 4:08 PM, "gseeling" <gseeling at smartfella.com> wrote:
>
>> e mail dave guerin, you can get him @piedmont models
>> ----- Original Message -----
>> From: "John Konneker" <jlkonn at hotmail.com>
>> To: <nsrca-discussion at lists.nsrca.org>
>> Sent: Wednesday, December 27, 2006 9:10 AM
>> Subject: [NSRCA-discussion] Guys I need help...
>>
>>
>>> I am working on my Focus II.
>>> I have the wing adjusters for one wing installed.
>>> In order to minimize the chances of a less than level table to affect 
>>> the
>>> incidence I decided to -0- the plane to itself.  The fuse sides at the
>>> canopy are supposed to be level with the "water line" so I put a level 
>>> on
>>> it
>>> to check...bubble at -0-.  I then double checked against the fin bed and
>>> it
>>> showed level.  I put a Robart incidence meter on the wing, set the panel
>>> to
>>> +1/4 deg and glued the wing adjusters on that side.
>>> This morning I was getting ready to do the other wing panel when I
> decided
>>> to do some measuring.
>>> Here is where I ran in to the unexplainable...
>>> I measured the wing leading edge to the table top and then the trailing
>>> edge
>>> to the table top.
>>> I show approx. .15 inches positive!
>>> I measured the leading and trailing edge to the piin stripe down the 
>>> fuse
>>> side (this stripe appears close to the water line) same positve 
>>> incidence
>>> shown.
>>> I then rechecked with my incidence meter and got +1/4 deg with the fuse
>>> level...I then "reversed" the incidence meter to check to see if 
>>> swapping
>>> ends had any effect...very little...maybe 1/8 degree...I can't read it
>>> that
>>> close.
>>> I then traced the leading and trailing edges on the fuse side with a 
>>> felt
>>> tip pin and rechecked my measurements to the table top and pin
>>> stripe...same.
>>> I am at a loss.
>>> How can I seem to be off this much?
>>> I could just cry....
>>> Any ideas?
>>> Thanks!
>>> JLK
>>>
>>> _________________________________________________________________
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>>>
>>>
>>
>>
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>
> . You are not off that much.  Your water line is the reference or thrust
> line and set to 0 degrees.  Good so far.  Your wind incidence is is 
> measured
> to the thrust line but the real height measurement is the length of the
> hypotenuse the triangle you created from the center of the wing tube to 
> the
> leading tip edge raised 1/4 degree from the adjacent side.  You must
> remember the further the distance from the center of the wing tube and the
> leading edge is the higher the leading edge will be at the same angle.
>
> If you have the measurements of the length of the Hypotenuse (center of 
> wing
> tube to the leading edge) and the angle of incidence you can accurately
> calculate the length of the opposite side using basic trigonometry.  It 
> can
> be calculated using the following formula; the height of the leading edge
> above the thrust line = the length from the wing tube center to the 
> leading
> edge times the SIN incidence angle)
>
>    SIN incidence = the length of the wing tube center and the leading edge
>    a = the height of the leading edge above the thrust line
>    A = incidence angle
>
>    a = c * sinA
>
> Please consider this when you are making measurements.  Unless the wing 
> tube
> is exactly centered on the wind and you compensate for the taper of the
> wings at the measurement point, then the distances  from the zero line 
> above
> and below the zero thrust line will be different.  The incidence meter 
> will
> accurately display the wings angle of attack relative to the thrust line
> regardless of the wing tube position and that is the more important
> measurement when setting up the airplane.
>
> When you  recheck the thrust line and verify the wing incidence angle is
> still at +1/4 degree then you are fine and unless you really like doing 
> the
> math enjoy finishing your build.
>
> I need to get back to my building table.....
>
> Randall Bearden
>
>
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>
>
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