[JoeF]

Details?

[Frank Colver]

Looks like a paraglider biplane to me.

Frank

[JoeF]

Which has one perhaps recall in delight:

Otto Lilienthal's double-decker

Rogallo's patent with biplane parawing

History of biplane hang gliders



Porter's at Otto 44:

Ellehammer: Tiny image:
ClickHERE for large image

Stacked wings in kite systems

Notice that the two types have an upper wing and a lower wing (or in case of the left first type, the lower wing is split to two skis; while upper wing is the pilot's body) :

And

Todd tests out the new Bi-paraglider, it was good but packing it away is a nightmare .....

Not to forget: https://activerain-store.s3.amazonaws.com/image_store/uploads/6/5/1/8/1/ar128632177218156.jpg

Train them early:

Keep the buddy system going in hang gliding!
You and your Buddy in recreational hang gliding! Two: and
2

Hybrid

ARP ::

[Frank Colver]

The photo that starts the topic is pretty unusual in that he has struts between the two paraglider wings.

What if one were to make those struts ridged inflatables? It might create a structure that would resist collapse, or at least rapidly recover a forced distortion in shape. One would have to analyze and test to see if that is the case.

Or some modification of the inflated struts to enhance anti-collapse support for the two paraglider wings.

Frank C.

[JoeF]

Toward Frank's note:

https://www.flickr.com/photos/amphalon/2210528610
or same Phoenix HPA

[ARP]

Having a biplane PG configuration may help prevent sail collapse when pilot weight goes negative in turbulence. With conventional PGs the intention is that the sail does collapse preventing it overflying the pilot in a downward arc as the pilot weight normally provides the pitch stability. The problem with this idea is that it takes height to re-inflate so the PGDMC comes into play. If the biplane aerofoil were reflexed then it might prevent the downward arc and so no need for the sail to collapse.

I have a sketch for a biplane PG that would resist collapse but with a greater separation than the one Joe put in his opening post. Unfortunately attachments are not working for me so cannot add sketch?

[JoeF]

Email sketch to me and I'll upload it to the topic, ARP.

[JoeF]

ARP sent this drawing of his. He had sent same drawing years ago to LIFT ezine. It is good to have it here in US Hawks Hang Gliding Association:

With flapped air intakes rigidity could be maintained longer
and the box structure would help prevent asymmetric collapse in turbulence.
The pilot is supported in a parallel frame to enable weight shift control in both pitch and roll.
Inter wing interference is reduced by spacing by at least one chord length.

Tony

bipg 001sm.jpg (53.38 KiB) Viewed 13343 times

[Rick Masters]

I totally understand why HG piltos thing PG is unsafe because of the rigidity of the craft they fly. It just does not make sense to most Hg pilots why pg wings collapse. Just think if our wing was solid, and we can make them solid if they wanted to... Kite boarding wings actually pump up theleading edge with air and maintain a certain amount of air pressure to keep them ridgid.. But I beleive PG is a safer aircraft with the ability to collpase...Again it all boils down to pilots judgements and thier ability to remain calm in certain situations. Also... When a PG wing collapses,, it will reopen at some point. Usually very quick and before the pilot knows it happened... In more turbulent conditions that may give a 50% collapse, with the right training, you can manage directional control somewhat and will be able to get the wing back flying. To me that is safe... The ability to reinflate the wing. Now... What happens when you break a side wire on HG... I think if you have an issue with the mechanics of a HG,, your pretty much screwed. With PG, I have known pilots to break many lines to the glider and still fly it, and not just the flight they broke on, but have launched with up to 7 lines broken... Infact, I have seen a PG cut in half from leading edge to trailing edge an still fly with out issue. The pilot hit a kite sting right in the middle of the wing didnt even know the glider was damaged , landed perfect with no issues. - Sean Buckner
http://www.azhpa.org/azhpa_forum/viewtopic.php?f=51&t=6230&start=10

The ones who haven't been killed yet think collapses are a safety feature, so don't waste your time.