Helium Kite Design ideas

[Leif]

Hello all,
Liz and I, here in NYC, have been thinking about a design for a helium
kite that would provide some of the lift of a balloon and some of the
lift from a kite while maintaining stability. We'd love to hear
peoples reactions and thoughts about this design.

<img source="http://farm6.static.flickr.com/
5087/5373239828_2fab11f9e2_z.jpg"/>

http://lpimaging.net/plots/heliumkite.pdf

[Jeffrey Warren]

looks exciting - you plan for the balloons to form a curve, like a parafoil? There are some kite designs like that:

http://www.windpowersports.com/kites/single/sled-kites.html

I'm also interested in using less helium now we know this will work -- perhaps a modified box-kite design such as one of these:

http://www.windpowersports.com/kites/single/delta-conyne.html

could work? Using a 1/2" PVC tube as a spar really helped us, I believe. 

Jeff

[Mathew]

Here are my thoughts:

FLYING THIS KITE
A kite that is lighter than air may be an asset vis a vis a standard
rammed air kite even if there wasn't enough helium to lift the
payload. If the kite could simply lift itself the first crucial
50-100 ft to get it in the air, it could reach a stable position
easily, and then the rig attached below and lifted by the wind.

Sail battens
I think the battens on the side are crucial to structural integrity.
The helium tubes may not hold their shape in the wind without
battens. Alternately, classic kite balloons ahve a balloonet:

Balloonets and hybrid ram-kites?
the interior of a classic kite balloon contains an air bladder
inflated by a duct or fan that keeps the structure pressurized against
the wind. Blimps work this way also. Perhaps a ram/sled kite
structure would work here?
look at this interior profile of a blimp for a better idea:
http://www.skytamer.com/2.6.3/Blimp%20layout%201600.jpg
and this kite balloon. Note the tube coming down into the basket. it
is attached to a blower:
http://www.headfullofair.com/wp-content/uploads/2010/10/airshipspastpres00hildrich-107.jpg


LEGAL PROBLEMS above 150ft
84" long is bigger than 6ft in one dimension- problematic for staying
unregulated. see my notes here:
http://wiki.grassrootsmapping.org/show/LegalInterpretation


ACTIVE VS STATIC LIFT
This kite balloon design will generate far more active lift than
static lift. I imagine this imbalance will make the kite balloon very
jumpy when the wind changes speed. (Jeff, did that happen with your
most recent balloon?) Most kite balloons are far more balloon than
kite. It seems to me that the goal of active lift structures on kite
balloons are to counteract wind drag on the static lift structures.

see the helikite. I want to make a kite like this. Just got some
EVOH sheeting in the mail yesterday, which is heat-seamable.
http://www.allsopp.co.uk/
http://en.wikipedia.org/wiki/EVOH

IDEALIZED VOLUMES VS REAL VOLUMES IN YOUR DIAGRAM
Your sleeping bag volume looks right, because at 16.72 cu ft it is
smaller than the 20 cubic ft I get for an idealized cylinder. Your
smaller kite cylinder volumes seem off though. I calculated 3237 cu
inches for the volume of idealized cylinders. But I'm assuming you're
not planning on seaming circular end caps, and seam the ends flat,
like the sleeping bags. Consider the way that shape will deform when
lined up in a row. I imagine the five pieces will inflate to look
something like this:
))|(( or you will have to taper some of your seams.

I'd fill up and measure the actual volume of a sleeping bag. you
can make a "measuring tube" like this one by seaming up a with a
circumference of 42 17/32" in diameter. Then every inflated foot
equals one cubic foot. I use such a tube for measuring air flow with
blowers.

[Jeffrey Warren]

Hi, Mathew - can you elaborate on the difference between static and active lift? I'm not sure I follow. 

As this design evolves, it may be a good idea to keep a PublicLaboratory.org 'tool' page on it. I think eventually if we find a really good design, we could order 1000 of them to be manufactured, with a built-in filling valve. The price for each should only be a few dollars, and we could sell/distribute them on the Grassroots Mapping site. However, I think its important that the designs remain "open-source" in order that anyone can reproduce them without restriction, even if we do decide to go in on an order together -- thoughts on that?

On a related note, the Grassroots Mapping wiki is quite full of spam these days -- apologies! Instiki, which I used to create it, is not great on catching spam. I'm thinking of importing the entire wiki (or its most recent state) into the Public Laboratory site, which supports wiki pages and is a Drupal site... that'll help with the spam, and make site administration much easier for me. Can anyone think of a reason not to do that?

jeff

[Mathew Lippincott]

static lift is the lift of a lifting gas, while active lift is the lift of a wing surface with air moving over it.

Good thoughts on the open source aspect- everything should definitely be copyable without restriction. I'll look at starting a page on the PublicLaboratory site soon.

As for valves, I got some 15-odd balloon valves from Gary at balloonkits.com, along with the EVOH sheeting.

--
work: cloacina.org/blog
play: headfullofair.com

[Mathew Lippincott]

Made a quick page for kite balloons- please add to it!

http://publiclaboratory.org/tool/kite-balloon

[Christina Ginder]

Our Children's Theatre is doing Mary Poppins this summer.  For the song, Let's Go Fly A Kite, I want a foil helium balloon shaped like a kite.  I've checked on line and found a few, but none I really like.  Does anyone have any suggestions on where to get a kite balloon?  The show is in doors, so need need to be concerned with wind.  Thanks for any help you offer.  Christina