anhedral on horiz stabs?

[gouch]

Hi all, i'm building a Bae hawk for the slope, and the full size has
anhedral (sp) on the stabs that are all moving.

What is the anhedral used for? (same as F4 phantom)
I'd like to replicate it on the model but was curious of it's true effect in flight.

The plane isn't true scale in the wings (longer span to fuse length ratio on the sloper) will this have an effect on the tail setup?
with thanks
Paul

[competitior]

Gouch;
Airplanes fly better, at high angles of attack, when the wing is mounted up high and the stab is mounted down low, (below the downwash from the wing). Anhedral in the stab has the effect of mounting the stab down a bit lower. Your glider will become quite a bit more stable and thermal better. Free Flighers have learned to just put the wing up on a plyon. If your subject has anhedral, I think you should put it in the model. The biggest disadvantage to anhedral is damage on landing.
Competitior

[Ollie]

A model with anhedral stabs, when in a banked turn and yawed into the turn, will have a small rolling moment applied to the stabs which reduces spiral instability.

[Sparky Paul]

"damage on landing" is the most important consideration. There's LOTS of damage on landing flying on the slope. With the extended span and high-mounted horizontal you might be OK.
Full-flying horizontals are also vulnerable. On my PSS A-7 I changed to a stabilizer/elevator because of its position on the bottom of the fuselage, to give it some rigidity when landing/impacting.

[gouch]

Thanks for the advice everyone, I will build it as the original.

Now the problem I have is how to build such a setup.

Does anyone have any sketches, links etc to show how linkages, may be used with an all moving anhedral style stab?

I have started to draw some ideas, but all have negatives.


Cheers
Paul

[Sparky Paul]

Turn this upside down....
The axle is the key. It's installed as if it were a landing gear wire on a sturdy bulkhead. The surfaces slide onto it, and gravity and the pull-pull wires keep them in place.
For anhedral you might need a more secure fastening system..
And use sheet. Built-up is way too fragile for a sloper.

[gouch]

thanks for that, does this setup use external linkages? If so I understand how to do it now, but if I was to try and drive it internally what would be the method?

Apologies for my ignorance on the subject but i'm having a struggle coming to grips with the setup, not ever seeing any models close up (or full size for that matter) that have this setup.

I will be using the balsa laminate over coreflute construction for the stab and fin that TFLG over in the slopers group came up with. It sounds like the best of both worlds, strong but with a better finish.

[Sparky Paul]

The control is external. Very difficult to do internally. You might ask the Jet guys with their swept horizontals (similar problem) how they get the control horns inside.
Two u-control horns might work, with one side whacked off... but support would be a problem, unless you can stagger the surfaces a bit.
You'd need an inboard and outboard support on each side.
The only full-scale flying tail I've worked with is the vertical on the -117. It uses a subfin for the outboard support, the horn is mid-located above the lower support. But the hinge axes aren't in the same line as a horizontal is.
..