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 Wind-inflatable fairing.
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Balor
human power supergeek

Russia
1058 Posts

Posted - 07/05/2020 :  14:03:49  Show Profile  Reply with Quote
A friend of mine has an idea about a 'wind-inflatable' fairing, needing absolute minimum of structural supports - think parakite/parasail.
It should be really light, can be tucked away like lycra fairing and while you 'deflate' at a traffic light it should 'reinflate' pretty much instantly and maintain it's shape pretty well.
Obviously not as efficient as hard shells, but should provide a good balance between weight and added speed in theory. A other possible benefit - some self-aligning to the wind, depending on supports.
Anyone heard of something implemented for this purpose?

strayray
Warren

USA
31 Posts

Posted - 07/05/2020 :  14:27:53  Show Profile  Reply with Quote
Tail socks can hold their shape from ambient air flow. The leading edge, probably not, since the ram air for inflation will be at the same pressure as the oncoming air. As for parafoils, wikipedia says: "The air flow into the parafoil is coming more from below than the flight path might suggest... When gliding, the angle of attack is lowered and the airflow meets the parafoil head on. This makes it difficult to achieve an optimum gliding angle without the parafoil deflating." You could experiment with scale models from plastic grocery sacks.

How about a hybrid, using a lexan winshaield for the front, and baggie the rest?
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Balor
human power supergeek

Russia
1058 Posts

Posted - 07/05/2020 :  15:22:03  Show Profile  Reply with Quote
quote:
Originally posted by strayray

Tail socks can hold their shape from ambient air flow. The leading edge, probably not, since the ram air for inflation will be at the same pressure as the oncoming air. As for parafoils, wikipedia says: "The air flow into the parafoil is coming more from below than the flight path might suggest... When gliding, the angle of attack is lowered and the airflow meets the parafoil head on. This makes it difficult to achieve an optimum gliding angle without the parafoil deflating." You could experiment with scale models from plastic grocery sacks.

How about a hybrid, using a lexan winshaield for the front, and baggie the rest?



Well, rather obviously it would look like F40 - a rigid tailcone with a 'scoop' on the front, and the rest is the 'bag' - with some minimal support sections...
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ElectricStreamliner
New Member

Australia
93 Posts

Posted - 08/15/2020 :  03:14:28  Show Profile  Reply with Quote
quote:
Originally posted by BalorWell, rather obviously it would look like F40 - a rigid tailcone with a 'scoop' on the front, and the rest is the 'bag' - with some minimal support sections...



I was picturing an inflatable bed like fairing with a cyclist suffocating inside haha.
A body sock makes much more sense.

Edited by - ElectricStreamliner on 08/15/2020 03:16:14
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warren
human power expert

USA
6578 Posts

Posted - 08/15/2020 :  21:10:11  Show Profile  Visit warren's Homepage  Reply with Quote
I have thought about inflatable fairings before. Not wind inflated ones, more like the air mattress type. With current materials it would add several inches of width and height to the failing though, so probably wouldn't be efficient aerodynamically. If you could build a fairing out of an abrasion resistant material that would allow a high pressure fairing then it may work. Maybe some kind of mylar fairing with a Kevlar cloth outer layer. It could be a very light yet efficient fairing.
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Balor
human power supergeek

Russia
1058 Posts

Posted - 08/16/2020 :  09:33:29  Show Profile  Reply with Quote
Frankly, I tend to agree, it would indeed be much more efficient and a good combination of light weight and even protection.
But actually making one would require a rather specialized seat of skills and know-how -though a combination of 'self-inflating', purely infalting and some structural elements might work too.
Will need to experiment with that eventually I think, but a bit low priority...
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SpiderMonkey
recumbent guru

USA
727 Posts

Posted - 08/17/2020 :  10:18:14  Show Profile  Reply with Quote
I fly an self-filling, soft, foil stunt kite sometimes. (Think of the parasailing ones, but smaller, only about 2m in length.)

Keeping it full in a light wind is a nontrivial task, and it folds up in sudden wind changes pretty easily. I tend to think that the amount of skeleton necessary to keep the thing "inflated" wouldn't be much more less than what's required for traditional skin or lycra fairings/socks.

--SpiderMonkey

Edited by - SpiderMonkey on 08/18/2020 16:02:51
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warren
human power expert

USA
6578 Posts

Posted - 08/18/2020 :  13:16:10  Show Profile  Visit warren's Homepage  Reply with Quote
Exactly! Thin CF rods (spars) inserted into sleeves in a ripstop nylon fairing would probably be lighter and certainly stiffer than an inflatabe fairing, but not as easy to stuff into a tailbox when it's not needed. It would be very easy to store though, certainly easier than my streamliner or other fairings that I do not have room for any more.
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alevand
human power expert

USA
3780 Posts

Posted - 08/18/2020 :  13:50:56  Show Profile  Visit alevand's Homepage  Reply with Quote
Inflatable kayak:


C:
Tony Levand
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