[NSRCA-discussion] Flying stab travel

Thu Sep 26 11:35:00 AKDT 2019

The most important thing about a flying stab is the balance point. Always...always balance nose (leading edge) heavy. This is critical. Otherwise it will “fly back” and nose down with no control. Deflection is more than a normal elevator. Remember that you need down force to balance lift. I scratch built a ducted fan F15 and had good success. I can’t tell you the amount of deflection. Unfortunately it’s trial and error. Start with large and dual rate it. Keep it slow for the first few flights. Experiment with faster speeds. Good luck! ...Charlie

Sent from my iPad

> On Sep 26, 2019, at 10:46 AM, Matt Griffitt via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:
> 
> The actual throw should be these numbers,    
> High.   15 to 17 deg
> Med.    8 to 14 deg
> Low.     5 to 8 deg.
> 
> You have to remeber that is way more effective than a elevator. 
> 
> The size of the stab is the same as a elevator and the cord also. 
> 
> Matt Griffitt 
> ADGaero.com
> 334.380.8228
> 
>> On Thu, Sep 26, 2019, 12:37 PM Scott McHarg via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:
>> Thank you all for responding.  Matt or Richard, can y'all give me maybe an "ish" idea of the chord at the root of the stab and a span or, even better, sq. in. of the stabs?  The numbers so far seem to be what I was expecting.  I was planning on having them set 3 rates.  Maybe one at 20 deg., one at 15 deg. and one at 10 deg.  I was wondering if it'd be about the same as the throw on an elevator.  Thanks again!
>> 
>> Scott
>> 
>> Scott A. McHarg
>> 
>> Takeoff is optional.  Landing is mandatory!
>> 
>> 
>>> On Thu, Sep 26, 2019 at 12:32 PM Matt Griffitt via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:
>>> A flying stab is more effected than a elevator.  Travel will be 60, or 70%.of a elevators travel. 
>>> I have been flying a flying stab for the last 8 years . On all of BJ Craft's planes the total amount of travel is 2.25 inches at the frount stab tube. 
>>> I hope this helps.
>>> 
>>> 
>>> 
>>> Matt Griffitt 
>>> ADGaero.com
>>> 334.380.8228
>>> 
>>>> On Thu, Sep 26, 2019, 12:11 PM Richard B. Strickland via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:
>>>> I agree on a pattern airplane (I have two BiSides with flying stabs—anybody want one?) as you have the advantage of forced airflow over the stab, but on an F4 twin 70 EDF, I run out of elevator on low rate at around 20 with flaps and slats on landing.  Maybe run 10-13 on low, but have some significant reserve on high, like 25+ and maybe 14-22 mid range for maneuvering speeds. Sounds like a fun project!
>>>> 
>>>>  
>>>> 
>>>> Richard Strickland
>>>> 
>>>>  
>>>> 
>>>> Sent from Mail for Windows 10
>>>> 
>>>>  
>>>> 
>>>> From: NSRCA-discussion <nsrca-discussion-bounces at lists.nsrca.org> on behalf of John Decker via NSRCA-discussion <nsrca-discussion at lists.nsrca.org>
>>>> Sent: Thursday, September 26, 2019 11:49:19 AM
>>>> To: General pattern discussion <nsrca-discussion at lists.nsrca.org>; Scott McHarg <scmcharg at gmail.com>
>>>> Subject: Re: [NSRCA-discussion] Flying stab travel
>>>>  
>>>> Scott, 
>>>> 
>>>> Normally, I set elevators at 10 degrees to 12 degrees for maiden. When I had a Nuance with a full flying stab it was so responsive I had it dialed down to 8 degrees by the time I had it trimmed out. And I found the radii could get sharp pretty fast so I had about 20% more expo programmed as well. Definitely more surface area makes a big difference. The nice thing is that once initial incidence is set, you adjust using elevator trim rather than incidence adjusters.
>>>> 
>>>> Hope that helps,
>>>> 
>>>> John
>>>> 
>>>> On Thursday, September 26, 2019, 11:29:40 AM CDT, Scott McHarg via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:
>>>> 
>>>> 
>>>> Howdy,
>>>> 
>>>> I'm looking for a little advice on a full flying stab.  I'm teaching an Aerospace Senior Capstone Design class at Texas A&M and one of my students' teams is scratch building a plane based on a supersonic business jet in sub-scale utilizing an EDF.  That part isn't really part of the equation but wanted you to understand what they're doing.
>>>> 
>>>> The team has figured out the design and mechanical connections which I have approved but we are needing an idea of how much travel the stab needs.  I understand that there are many variables including size of the stab, CG, AC, etc. but I'm looking to give them a place to start.  I was thinking of the Bi-Side and wondering if someone could give me, in degrees, the amount of travel for the stab so that we have a starting point.  I'm sure I'll have fun with the maiden but, hopefully, we will be in the ballpark.
>>>> 
>>>> Thanks!
>>>> Scott
>>>> 
>>>> Scott A. McHarg
>>>> 
>>>> Takeoff is optional.  Landing is mandatory!
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