[KaiMartin]

I just stumbled on the video below about a wind tunnel test on a remarkable wing. The wing is VERY bird-like to the point that they actually use feathers of sorts to form the airfoil. The construction accepts a single pilot in prone position, much like a regular hang glider. But unlike a HG the pilot can directly control the orientation of wings and tail. The design looks really sleek. Somebody must have invested quite a bit of effort and money to get this far.

The video is from 2013. Unfortunately search machines return empty handed when told to look for any follow-ups. Apparently the project stalled. I'd be curious for the actual reasons. Did the wind tunnel tests reveal severe aerodynamic problems? Did they fail to find a solution to the weight problem? Did some investor loose interest? What do you think?

[Bob Kuczewski]

What do you think?

I think they had some really great bird footage near the end!!

Thanks!!    

[Frank Colver]

Interesting!

Back in the 1970's a guy (I don't remember his name) came to our SCHGA meeting in Los Angeles with drawings of a similar machine. His "feathers", in the drawing, looked almost exactly like the ones in the video. He didn't have the money to build it and was looking for financial help which i don't think he got. I never saw the drawing again but he had attended more than one of our meetings and may have been flying HG's also. I don't know if his plan included a similar control system or not.

Yesterday I was watching Ravens "parachuting" down from a structure to a spot on the ground with very little forward motion. I was thinking: "I wish i could do that with my hang glider".

Frank

[wingspan33]

KM,

I looked up Frigate (AC) Limited, and a web site connected with business info says -

Company status . . . . . . . . Dissolved on
. . . Dissolved . . . . . . . . . 2 May 2017


The business was located in the UK. The head man was Peter Jeremy Dodd.

As far as what I think happened, . . . Not enough money. Too heavy. It looks very obvious that the wing and "feathers" are constructed of metal.

I'd bet that the metal version was a cheap way to show the form, how it would be controlled and do the basic wind tunnel testing.

To make it lite enough to fly much would have to have been custom made of carbon fiber. I can also imagine each of the feathers needing to be a carbon fiber skeleton of sorts draped with Dacron fabric (or Mylar?) making up 90%+ of the surface area. That would make each "feather" very expensive. And considering all that, there would be no way production models could be made without charging the final customer at least $100,000 - for a bird glider.

As shown in the video it's an amazing creation. I'd love to see it close up. It'd be a pity if when the company failed the whole "bird" was thrown in a scrap heap - or recycled. I could see it fitting into an interactive science museum where kids and adults could manipulate the controls and see the resulting control movements.

[wingspan33]

. . . Yesterday I was watching Ravens "parachuting" down from a structure to a spot on the ground with very little forward motion. I was thinking: "I wish i could do that with my hang glider".

Frank

A few decades ago I remember seeing a video of the Kasper Wing. In the video they showed an in air stable stall (clearly shown by smoke bombs mounted on the wing) where the wing would lose altitude - without going into a dive - with little or no forward movement. The Kasper Wing was also supposed to be able to "tumble" during horizontal flight.

So Frank, maybe you can find a Kasper Wing and join the ravens. I don't think there's a hang glider pilot alive who wouldn't give anything to have a human sized set of fully controllable bird's wings!

[Frank Colver]

My Skysail had a high angle flying mode where the wing was controllable (not stalled) but had a descent about like a standard Rogollo. At first I thought it was a very poor glide for the wing. After I discovered that I was launching and flying in this high angle mode and if it was launched and flown at a lower angle the glide was very good.

I think it was Horon who described a similar situation and he attributed it to a large rotor forming above the wing at high angles of attack and forming a virtual airfoil with the flow going over the top of the rotor and then down toward the TE looking like a very high cambered airfoil. I always thought this was what I was experiencing. The glide descent in this high angle mode was like an aircraft with very large flaps - slow and steep.

Unfortunately I could launch in this 2nd mode but I couldn't enter it from normal flight because the energy stored in the wing would take it through this upper area and into full stall unless done very slowly. That was of little use when landing and rotation has to be fairly quick (normal landing runout was similar to the flex wing hang gliders of today).

This dual mode observed is one of the things that make all-wing designs so fascinating.

Frank

[KaiMartin]

@wingspan33:
To me the close-up of the feathers at 0:54 suggests they are thermoplastic polymer sheets. Maybe a sandwich with the borders welded and cut by a heated wire.

Weight is certainly a major issue. The mass of the wing cannot exceed about 50 kg if the glider is to foot launch. With all the parts and mechanics the black stuff must be really light and still stiff enough to maintain its shape. It must be literally "light as a feather". I feel, even regular carbon would be too heavy for the job. But maybe my feelings are wrong and there is a way to build a hang glider with man made oversized feathers.

I like the way the pilot is attached to the wing rather than hanging from it like a pendulum. This would probably lead to a much better feel for the state of the wing.

There is a potential problem with the control concept of the frigate. They can tilt the tips of the wings. The tail can go up and down and rotate. Apparently, they wanted to use the tail for pitch control. In addition, they wanted to control yaw with a rotating tail. However, this is not what nature teaches. Birds either use their tail for yaw (e.g. birds of prey). Or they use it not at all most of the time (e. g. sea gulls and albatrosses). Yes, albatrosses sometimes use their tail as can be seen in second half of the video. But this is a very special circumstance. The bird wants to hover in place. That is, it needs to adjust its air speed and lift to exactly the right amount. In this scenario tail and feet are used as variable air brakes. Once the albatross decides to leave, it promptly folds its tail to a minimum.
Bird configurations are severely unstable in pitch. So if soaring birds don't use their tail to control pitch, how do they prevent themselves from unintended dives? They can tilt their wings slightly back and forth. This shifts their weight with respect to the effective center of lift.
The frigate concept does not seem to do such a weight shifts. IMHO, this means insufficient pitch control. A test flight would probably enter an uncontrollable dive fast...

That said, I feel bird like gliders just may be possible when done right. I'd really, really love to soar the coast with a wing like the frigate!

---<)kaimartin(>---