Is there more Information on Flac a british 60lb Carbon Fiber Foot Lauch glider by Richard Gerrard?

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patrickrio

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I am guessing that it is just a design and it appears to be overly optimistic in the weight department. But I would like to see design drawings or sketches or something anyway.

I found mentions of it on a few websites but the only site that has information on it is nest of dragons. here is the nest of dragons link: Flac by Richard Gerrard

Is there any other information or contact info for Richard anywhere? When was this design work being done?

The fact this is a pod and boom glider with a regular tail and 3 axis control just seems impossible to consider at the weight. I want to see how he thinks he can do it.
 

ypsilon

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The description on NoD doesn't sound like that glider was actually built.

The main problem with pod and boom footlaunchers isn't really the weight, but the static (empty) c/g. That's why the tail needs to become very light, and thus fragile. Look at ruppert's Archaeopteryx. This is a very optimised implementation of the pod/boom 3axis hangglider. It won't get much better than this.
 

patrickrio

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The description on NoD doesn't sound like that glider was actually built.

The main problem with pod and boom footlaunchers isn't really the weight, but the static (empty) c/g. That's why the tail needs to become very light, and thus fragile. Look at ruppert's Archaeopteryx. This is a very optimised implementation of the pod/boom 3axis hangglider. It won't get much better than this.
Yes, I assumed the craft was not built yet. I still wanted to see how they thought they could get to that weight. They supposedly did manufacture composite material samples to base that weight estimate on. What was the nature of those samples? What was the resulting design?

The lowest weight pod and boom glider I have found with more than a few constructed is the Haig American Eaglet that supposedly had and empty weight of 110lbs in engineless glider form. The next lightest with a decent number produced that I have found is the Archaeopteryx at 119lbs in engineless glider form.

The American Eaglet is constructed with metal tube frame with fiberglass skins. The reason it is lighter than the Archaeopteryx is basically because it was not designed for foot launch, so total aircraft CG does not vary widely between take off and gliding regimes like a foot launch does. Also, stall speed of the eaglet is 38mph instead of the speed a human can run while carrying a 119lb glider on their back.... and of course allowable pilot weight is very low in the eaglet also. eaglet pilot max weight is 170lbs where Archaeopteryx max pilot weight is 225lbs. The eaglet may have also made some pilot safety trade offs for reduced weight as compared to the Archaeopteryx pod construction.

It is likely that a glider made with the most modern carbon fiber parts used with extreme weight reduction in mind could improve the empty weight from that of the eaglet, but not by much I would guess.

That is why the claims of 60lbs empty for a craft that can foot launch is something I would like to look at. How did they come to the conclusion they could pull that result off? How well calculated/thought out is the resulting design?
 
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ypsilon

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I don't know anymore about this project, than what can be found on NoD, but as somebody, who's building a foot-launcher myself, and who's been around in this scene for many years, I don't believe that this is more than vapor ware:

1) L/D > 25 with an A/R of 11? Even with a laminar section, very clean wings, you'd need an equally clean pod / boom / tailplane. Hardly possible even without weight restrictions.
2) Stall speed 15 kts (abt. 7.7 m/s) means that you'd operate at an (3D) cl of about 2.7. Again: A/R 11. That is impossible without slotted flaps/ slats or other high lift devices, which are completely inappropriate for foot-launching, because of their weight and the drag they generate.

It continues like this, all the way down. They had charming ideas, but they haven't figured out any of the details (let alone built anything).

To me this looks similar to many other projects dreamers dream about. Don get me wrong: It's ok to be a dreamer (mandatory to become member of this forum, I guess), but many people don't realise how much work is require to build a glider almost as good as the one's commercially available, not to mention something new and innovative.

When it comes to footlaunched sailplanes, the Archaeopteryx and the Swift Light define pretty much the performance limits. I think they also define the limits of acceptable unwieldiness on the launch site.

If foot launching isn't a concern, and you are only looking into light sailplanes have a look at a classic: The Akaflieg Darmstadt D28 Windspiel (57 kg), but a Vne of 180 km/h, simple aerobatics allowed, and a distance world record in the early 1930s.
 

patrickrio

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To get down to 60 pounds, you need to cut off entire sections of the airplane... like the tail and tailboom.
Exactly what seems true since 60lbs seems to be near the limit for semi rigid wing hang gliders designed for very light pilots...... a flimsier version of the flac with no tail, boom or full pod built for a lighter pilot...

I want to see what they did to justify that weight.
 

Hephaestus

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The lowest weight pod and boom glider I have found with more than a few constructed is the Haig American Eaglet that supposedly had and empty weight of 110lbs in engineless glider form. The next lightest with a decent number produced that I have found is the Archaeopteryx at 119lbs in engineless glider form.
Hippie_H-111_at_Sinsheim.jpg

110lbs in the 60's...
 

patrickrio

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Sorry, I did remove some super light primary gliders that had poor L/D ratios and no pilot pods. Including Hippie and Bug.
 
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