Dave Fitzgerald's article on Stabilizer Leading Edge Shapes?

[Joe Ed Pederson]

I'm pretty sure it was Dave Fitzgerald who had an article in Stunt News about his experiments with different shapes for the leading edge of the horizontal stabilizer.  Does anyone know/remember which year and issue of Stunt News has the article?

Thanks,
Joe Ed Pederson

[Ken Bird]

Try Mar/April 98, P. 36

[Joe Ed Pederson]

Thanks, Ken.

That is the correct issue and fortunately I have that issue somewhere.   It's a good thing I have the hard copy because the March/April 98 issue of Stunt News that is archived on the PAMPA website is missing pages 37 and 38.

Joe Ed

[Brent Williams]

https://stunthanger.com/smf/open-forum/copy-of-the-david-fitzgerald-article-'de-tails'-from-the-marapr-98-stunt-news/msg511544/#msg511544

[Ken Culbertson]

I wonder if there has been any change in the preferred since '98.  Except for my planes, I don't see very many "C1" stabs around here.  Just curious.  The chart seems to downgrade tip plates, but they only appeared on one test.  Those are in abundance around these parts.

Ken

[Jim Svitko]

I have been using something similar to the C1 configuration for a few years now.  I do not have the leading edge as pointy but the concept is the same.  I think the tracking is better, and I can also get better corners with no bounce.

I will not use a flat stab with the leading edge simply rounded off to a semi-circle.  It works, but I have an easier time controlling the plane with the C1 configuration.

I never messed with tip plates.  I doubt I would notice a difference.

[Brett Buck]

I wonder if there has been any change in the preferred since '98.  Except for my planes, I don't see very many "C1" stabs around here. 

      Yes, I can't see why anyone would use something like that. Everybody make them flat with pointy LEs!

      I also note that David's "C1" stab was run on 3 different airplanes, the problem with it being that the construction is too heavy, not that is it the wrong shape.

       Brett

[Ken Culbertson]

      Yes, I can't see why anyone would use something like that. Everybody make them flat with pointy LEs!

      I also note that David's "C1" stab was run on 3 different airplanes, the problem with it being that the construction is too heavy, not that is it the wrong shape.

       Brett

I see your point.  What you are saying is that the flat pointed LE stab is good enough but a light airfoiled would be better.

With CF and a good geodetic structure, it should be possible to build a light enough airfoiled stab.  Mine are coming in at 75-80grams with horn and hinges but no tip plates.  I am embarrassed to admit that I have no idea if that is heavy. Last plane weighs in at 70oz with an empty 6s battery which is on the leading edge of heavy (big motor).

Ken

[M Spencer]

Somebody mentions 2 1/2 ounces. in his Stiletto artical . RIDGIDITY is a THING not to be ignored .( no flex under working / gust loads .  A carbon thread on the L E .( & above & below spar .)
So they say . send me your carbon thread & we'll know ! 
ACTUALLY Bob Hunt & Carbon Veil & RIDGITY might be worth consideration .If WEIGHT & ridgidity is the requirement . Money no object .: We use Oak. whats ten ounces between friends . 

[Dennis Toth]

Rereading the article it seems the C1 airfoiled stab & elevator is the shape used on the Nobler just more % area. If C1 is built up like the Noble should be lighter maybe just some creative structure is needed for more stiffness. The A3 with the 0.022" wire is simple, the shape leading edge version seemed good but the wire version was better, brings up the question could you just shape the leading edge to the 0.022" wire rather than very pointy? So where is the limit to the radius? Is it related to the stab thickness or just the leading edge separation point?

The airfoil shaped configuration is also used on the OTS Don Still Stuka, but it is close to 3/32" rounded leading edge, mine wants to hunt a little in the wind. Might try adding the wire and see if it calms down some.

Best,    DennisT

[Ken Culbertson]

I think that weight is relative to the overall weight of the plane.  A heavy stab on an otherwise light plane leads to nose weight and visa versa.  Since I have only had to add tail weight once that I can remember, maybe mine are too heavy.  They are stiff and "pointed" 1/32" CF strip imbedded and semi sharpened.

Ken

[Brett Buck]

Rereading the article it seems the C1 airfoiled stab & elevator is the shape used on the Nobler just more % area. If C1 is built up like the Noble should be lighter maybe just some creative structure is needed for more stiffness.

      But, in fact, it wasn't lighter. It does fly better, but weight in the tail leads to lots of weight in the nose. In my case, of course, I use the one David calls "C1", it's the Infinity tail airfoil (without the rounded corners), which is of course the bases of the experiment. Mine does not weight 89 grams! And it is more-or-less a Nobler tail airfoil. Ironically, I always end up nose-heavy, sometimes by a lot.

    I also note - there has been A LOT more learned about this since then, in particular, elevator wedges, which seem to work about the same for all the tail designs. In my case, at least my first few tries at wedges have been *far too effective*, with the expected effects but also some odd effects with control response at various speeds. There are other protuberances like tripper/zigzag strips and VGs that have variable effects on different airfoil shapes - nearly no effect on my tail, marked effect on "flat stabs with pointy LE" stabs, etc.

    Brett