[NSRCA-discussion] Annhedral Stab

[J N Hiller]

Thanks Nat, I will need more actual application info.
My past experience with scale aerobatic airplanes having the stab in the
scale location usually quit high relative to the wing position all pitched
hard to the belly but those with the stab lowered didn't have near the
problem. I thought it was because of the high stab position but it may be
due to something else. I guess I need to build a test airplane with a stab
that can be mounted in several vertical locations, someday.
Thanks for your thoughts on this.
Jim

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Nat Penton
Sent: Monday, April 21, 2008 10:42 AM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] Annhedral Stab

It is my opinion wing/stab vertical separation is immaterial - other than
for wing/stab interference considerations.

The downwash is a tube the diameter of the wingspan, so one inch up or down
vertically with the stab is the same difference.                       Nat

----- Original Message -----
From: "J N Hiller" <jnhiller at earthlink.net>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Monday, April 21, 2008 4:20 AM
Subject: Re: [NSRCA-discussion] Annhedral Stab


> Downwash:
> I almost mentioned downwash earlier as a seemingly significant contributor
> to flight trim / setup. Vertical positioning of the stab in the downwash
> appears to be important when matched to aircraft weight and horizontal
> flight speed.
> Would it be safe to assume that having a flat stab in line with the wing
> would produced a pitch to the canopy or dose running that deep in the
> downwash just make it hunt?
> Thanks
> Jim
>
>
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Nat Penton
> Sent: Sunday, April 20, 2008 9:38 PM
> To: NSRCA Mailing List
> Subject: Re: [NSRCA-discussion] Annhedral Stab
>
> Jim
> I used anhedral, about 5 degrees, on my Express because the wing/stab
> separation is effectively zero. My fear was interference from the wing
> shear
> line and the idea was to have the stab operate in a broader range of the
> wash.
>
> It is impossible to get the stab out of the downwash.
>
> I have experienced heart pounding rudder interference from forward fins
> and
> wanted to avoid those puzzling instances of "was that me or was that the
> airplane".
>                                        Nat
> ----- Original Message -----
> From: "J N Hiller" <jnhiller at earthlink.net>
> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> Sent: Sunday, April 20, 2008 1:01 PM
> Subject: [NSRCA-discussion] Annhedral Stab
>
>
>> Can I open a discussion on why some designs have an annhedral stab?
>> Was it to lower the effective flying height of the stab to reduce the
>> wing
>> to stab vertical offset and knife edge belly pitch, or is there some
>> other
>> reason?
>> Jim Hiller
>>
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