Does anyone recall if the Joe Bridi's "Dirty Birdy" incorporated anhedral on the horizontal stabs?
What is the purpose of building this type of configuration? Does it position the tail surfaces in cleaner air? I'm pretty curious, as I had a discussion with a co-flier and neither one of us knows what we're talking about. [:-]

The Birdy stab is flat. You are thinking of the Tipporare or the UFO. I think they both had anhedral in the stab.

Anhedral was designed to make outside loops smootehr and not prone to tucking the nose

YEP - Now that you bring it up, you're right on target. I was thinking of the UFO. I was introduced to all three of them at about the same time frame.

Thanks....

Yea, the UFO was nice. I still have a glass birdy with retracts. I really need to get that in the air. Just needs paint. Has for 15 years.

The Curare was also famous for the anhedral stab
This is a photo of the one I'm building

FlyBoy - I'm getting a Dirty Birdy for Christmas and will be building it for my winter project. Once completed, I'll have Joe Bridi's trio of Sunfli V, Utter Kaos, and the DB. Interesting to see the side-to-side comparisions of these models.

Apalsson - That is a good looking plane! I really like the tail section. Looks to be very stout.

I am now curious about the reason for the anhedral. There must be a reason other than what jsenicka suggests about the outside loop, as the full scale F-4 uses this configuration.

Many years ago I flew the F4 Phantom II, including the F-4E in Vietnam. Much of this info came to me at the F-4 Training school.

Regarding the F-4 Phantom II, if you will take a look at McDonnell designs, you'll notice that once that got past the original FH Phantom I and F2H Banshee, the rear fuselage was small diameter and extended out above the engine exhausts. The F3H Demon, their only single engine, as I recall, and XF-88 Voodoo were like this and had low flat stabs. In order to get the stab in better air for control at high angles of attach, the F-101 Voodoo had a T-tail arrangement. This had pitch up problems at high AOA. Since they couldn't lower the stab any more than on the F3H because of the fuselage design, they drooped the stab in an anhedral arrangement.

This worked fairly well for the initial proucdtion models, F4A & B, navy, F-4C & D USAF. Sill wanting more stabilator authority, they added slots on the leading edge of the USAF F-4E and the navy F-4J models. These increased lift and the E's I flew had much better elevator control on landing and take off than did the C's or D's.

It is also interesting to note the background of the dihedral tips. The original test plane had a foat, no dihedral wing. The sweep along did not give enough stability and it was determined that some dihedral was needed. Changing dihedral is not easy (except on RC planes). It requires both wing and fuselage modifications, both of which are costly. The solution was to add a wedge in the wing fold area to raise the tips to get the required stability. This was both easy and cheap so it was adopted rather than breaking the wing in the middle.

Left to right: XF-88, XF3H, F-101, F-4C

From what I remember from those days, it was also used for cross wind landings. It helped to keep the plane flying straight. I have a 90% built Curare that I am dieing to get in the air. I changed the material used for the Curare to liten it up a ton. The turtle deck is built up and sheeted instead of the 1/4 and 1/2 inch balsa. Mine is at just over 5 pounds with engine, main gear retracts less radio. There is a pic here of it. http://www.rcuniverse.com/gallery/ga...memberId=14276


Dru.