From the ARF Dirty Birdy coming out,...and building a dozen and a half Kaos's in my 41 years of flying,...I started thinking about the Real Slick Pattern Planes like the Mach 1, and the Mixture by the Great Hanno Prettner.

So I have a question for the Forum: Does any one remember some of the Aircraft that had a Horizontal Stab that was on an Anhedral?

Thank You in Advance,..
Michael Giles,
Tomah, Wisconsin 54660

Mixture? I think I'm reading things wrong.

More to the point, I'm not sure what you're asking? After the Curare came out, well, every man and his dog had anhedral stabs, but it wasn't a pattern panacea and it died off fairly shortly.


Incidentally, everything old is new again, and my last two F3A ships have had anhedral stabs also.

The trend may have been influenced by the F-4 Phantom.

The trend may have been influenced by the F-4 Phantom.

I'm flying Hanno's Calypso which came after his Curare, and it's no looker, but it wasn't beat at the last BPA, he he he.
It's really almost ugly .
Got to learn how to post pics
Jamie

Thanks for jumping in Gentleman,....Rendegade, it is quite possible I have the name completely wrong!
Your last couple of F3A A/C with an Anhedral, would you be so kind as to post a few photos?

Michael,

MajorTomski,

I believe you are correct, they probably were influenced by the F-4 Phantom. Funny you should mention,..I Flew the OH "Double Ugly"
in the USAF for 13 Years. Fabulous 60K pound machine.

RF-4C.... Reconnaissance. The Stab was 23 Degrees,....and it was not Differential. Subsequent US Fighters,...F-14,
F-15, f-16, T-38, F-5, F-20, F-111, and others, all had "Full Flying Stabilators, however they are Differential.

Michael,

One ones meat is another man's poison I guess.

Well guys, it was not for looks, it was for a rudder pitching problem... Here is aPDF from Dave Brown on the subject.

A well know pattern flyer told me it effectively increased the side area on the tail, which would decrease the "wiggle" or over rotation that follows a hammer head.

The Curare was the plane that set off the whole anhedral craze. When Dave Brown dominated the field with the Curare, folks were obviously drawn to the bent tail and started asking questions. Yes, Dave always said it was there for a reason, but many folks throughout the years spent way too many hours disproving the reasoning behind the bent tail. I finally gave up trying to understand the aerodynamics of it and decided that if it worked for him on that one model, then great.

Was it the anhedral tail that made the Curare so great? Smarter folks than me can continue to hammer on that, but having flown enough pattern "back in the day" as well as some SPA, I am of the opinion that the tail was much ado about nothing, and not enough credit is ever given to the pilot. Other designs had (or offered) anhedral tails. The Bootlegger could be built either way. many built it straight, many built it bent. Both swear by their personal decisions, but many who tried the Bootlegger each way decided it flew a little better with a straight tail. So... a bent tail in and of itself isn't really a factor. I never owned a Curare, nor did I ever see one without the bent tail.

I don't think Wolfgang Matt, or Hano had bent tail models, and I don't think the Joe Bridy designs ever went down the anhedral road. As was mentioned by somebody earlier, the bent tail came on the scene and spread like crazy, then vanished nearly as quickly. As "turnaround" came on the scene (effectively killing most of the joy for the majority of pattern fliers) the planes started evolving into completely different machines bearing little (if any) resemblance to the models that established "the hey day" of AMA pattern flying. Bah... really didn't mean to enter into a rant. Sorry guys.

My memory may fail me here, but I think the Curare, Tipo, Illusion, Bootlegger, Sky Knight represent the bulk of the bent tail models, with the Bootlegger having it as an option. I don't recall the Atlanta or the Aurora having anhedral either.

XLT had the bent tail...flew great!

Chris the curare is the model that touched off the anhedral movement. It was Hanno's design. Dave Brown only copied it when he and Dick Hanson developed the Tipo.

As does Bridi's UFO!

Brian

The Calypso is a fantastic flying ship. It just looks like a leaf in the air. Could use some dolling up on the color scheme.

I don't know what effect anhedral had on the early pattern planes as I wasn't flying then. But my current pattern ship is a Valiant which has anhedral stabs. Combine the anhedral with the correct CG and the aircraft will track on knife edge rudder only. No pitching problems to mix out.

I flew the Magic with the bent tail and it seemed to track better. My rolls looked better, as did my four point rolls. Truely enjoyed the Magic. I Flew the T2a one season when the Curare came out with the bent tail. Thought seriously about bending the tail on it.

Frank

Definitively, the anhedral stab was used to control the pitch down tendency in knife edge when the rudder hinge line was moved back to vertical.In knife edge, think about this: the fuse had a positive angle of attack. The bent stab then gave an effective "up elevator" component. Visualize it, please.The same effect can be had by moving the rudder hinge line to less than vertical. Think "Taurus" generation. That effect was for extra up elevator for spin entry, but take one of those (Taurus, Orion, Perigee, etc.) and put it in knife edge, add the rudder, and behold, it climbs to the canopy like a demon!Downside of the anhedral stab is that in a cross-wind, it would make the plane pitch up. Rudder hinge angle did not have that problem.In the desire for true neutral response to control inputs, most designers left the rudder hinge line vertical, and compromised by doing other things. Remember, in the Curare days, there was no control mixing in the Tx.Does that help to clear things up?

What WEDJ said, plus the anhedral stab in knife edge counteracts the tendency to roll out of knife edge. This tendency is caused by 1. the wing dihedral and 2. most of the fuselage side area being above the centre of mass.

Also, there did exist a Curare without an anhedral stab. The Prettner designs previous to the Curare were the Sicroly series. The last of those, the Super Sicroly 2, was pretty much a Curare without the anhedral stab, and the stab placed lower on the fuselage. Hanno Prettner won the '75 TOC with the the Super Sicroly 2, before winning 2nd place in the '75 World Champs, 1st place in the '76 TOC and 1st place in the '77 World Champs with the Curare.

G.

Anhedral: Part fad, part fact. Whatever. It just looks KOOL! You know, '70's kool.

If one prefers an aft CG, be careful with anhedral stabs. Aft CG and cross wind will cause all kinds of headaches on the anhedral stabbed model. The pitch up in S&L flight (stab forced down) is very weird and noticeable by even casual observers. My latest design uses the geometry and I really hate the model's cross wind flight character. Had to move the CG fore to about 25% static margin and it barely holds its own

The anhedral stab is supposed to assist model lock in all attitudes during rollers and such. In my experience it really didn't help these maneuvers.

The anhedral stab does not counteract any tendency of the wing to roll out in knife edge, unless the dihedral angle of the wing was incorrect in the first place. Get the wing's dihedral correct and you don't have to worry about your model rolling out in knife flight.

The anhedral stab adds vertical volume to the tail so directional effectiveness is ever so slightly improved. But if one wants directional stability, simply add fin area. Simpler and easier to get exact