RC Blimp envelope material

[Kyle Hord]

Everyone,

I'm looking to make some custom RC blimp envelopes. I know you can buy the traditional saucer and tear-drop shapes, but that is not what I'm after. Anyone know where I can procure some envelope material? (Whitestar people may know this)

If seen online people taking the emergency Mylar blankets, and gluing them together. That seems to be touchy in creating a good seal. 

Kyle

[Brian Wagner]

You can buy cheap mylar balloons with helium a the dollar stores.  Cheapest place in town for balloons.

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[Ben Hibben]

I will inquire with the RC blimp racing folks I know who make their own.

Blenster

[crei...@sdf.lonestar.org]

I've thought about this myself, and have considered buying traditional
parachute material, sewing the desired shape and then spraying both sides
with silicone waterproofing spray. Alternatively, sewing the shape and
then stuffing the volume with multiple mylar balloons would work under
certain circumstances.

You could also look into heliostat shapes for ham radio operators, which
are not designed to fly untethered, but some of those shapes are rather
unique and can provide significant lift.

Creighton

[Kyle Hord]

I have worked with parachute material on past projects, and it is much too heavy for the scale I am working at. Plus even with a spray, it would be near impossible to seal it to the grade metallized nylon or mylar would for helium. For water or air, it would be great. 

I primarily need to make a torus shape balloon and would like to avoid taking mylar balloons and cutting them up.  I am trying to stay custom made, so I can fit the envelope to the application, rather than fit the application to the envelope. Far less complicated. 

[essobi]

I’d imagine would could use a heat sealer if careful…

What sort of shapes are you aiming for?

-SOB

[crei...@sdf.lonestar.org]

>
> I primarily need to make a torus shape balloon and would like to avoid
> taking mylar balloons and cutting them up.
>

An innertube wouldn't work?

[Brad Luyster]

Way way way too heavy.

White Star found a couple sources, but abandoned that part pretty early. I'll see if I can dig up any info. How much do you want? Thermal sealing is definitely the way to assemble.

[Kyle Hord]

I agree, the thermal sealing would be a major bonus. To start, I would need about 20 square feet for experimenting and then maybe a small amount again later on.  Does not matter to me if it comes in a roll or sheet, I can work with it. 

[Christopher Cprek]

How about donut balloons?

http://www.ebay.com/bhp/donut-balloons

[Ben Hibben]

As promised I asked a friend who makes his own blimps and organizes races and he sent me this:

http://steampunkchronicle.com/ArticleView/tabid/238/ArticleId/494/Building-Your-Own-Airship-Envelope.aspx

And you can join facebook/steampunkairshipracers where we cover that topic in detail.

Thanks,

Dan

His name online is Deadline Dan and he's a super nice guy and a good maker.  I posted a picture of his vacuum-form machine in his workshop; good quality workmanship on it.

Blenster

[Kyle Hord]

Chris: If I could find a 4ft major diameter, with a 1 foot minor diameter torus pink donut balloon, my troubles would be solved. It would only make my project look majorly awesome. 

Ben: Thanks for the link. It looks like he got his supplies for a website I found earlier. That may simply be the best option to pursue. 

[crei...@sdf.lonestar.org]

> I agree, the thermal sealing would be a major bonus. To start, I would
> need
> about 20 square feet for experimenting and then maybe a small amount >again
> later on. Does not matter to me if it comes in a roll or sheet, I can
> work
> with it.
>
>

Get a bulk pack of space blankets from ebay. The set I bought are about
10 feet on a side.

Creighton

[Kyle Hord]

Unfortunately the space blankets do not have the polyurethane coating on them that allows for the thermal sealing. But if all else fails thats the plan. 

[crei...@sdf.lonestar.org]

> How about donut balloons?


All this talk about torus shaped lighter than air drone makes me wonder
how viable a hybrid lift quadcopter might be. Perhaps a small one with a
large hydrogen/helium torus around it's entire outside; or perhaps four
such torus's around each of the ducted fans.

Or maybe just a regular weather balloon attached to the quadcopter's
center by a fishing line. If the quadcopter could be made lighter than
air, it would be able to carry a greater load.

Creighton

[Ben Hibben]

Might try looking for a sonic welder to seal it lacking thermal sealing.  Harder to come by, though.

Blenster

[Kyle Hord]

Creighton: Thats exactly what I am doing. I'm trying create a ballasted quadcopter with light weight solar cells. The entire system will be pretty small, but the idea is to use the balloon to offset the weight to all of a reduced power requirement.  

[crei...@sdf.lonestar.org]

> Creighton: Thats exactly what I am doing. I'm trying create a ballasted
> quadcopter with light weight solar cells. The entire system will be >pretty
> small, but the idea is to use the balloon to offset the weight to all of >a
> reduced power requirement.
>

Are you trying to make it solar powered in flight? If not, then the
innertubes should be a better deal overall. They are heavier, yes, but
more durable; so they can be used as landing gear and general impact
buffers. The balloon material won't put up with that. As long as the
innertube is light enough to be positively bouyent, it's just a matter of
getting a large enough tube filled to slight pressure. During daylight
(which I assume is the point) the black innertube rubber would also gain
some degree of temp lift. A small quadcopter, surrounded by a tracter
tube filled with hydrogen to almost full (balanced pressure), will have a
much larger upper surface area in order to install lightweight solar cells
anyway. Net bouyancy is probably unrealistic, however.

Creighton

[Kyle Hord]

A rubber innertube is out of the question, they are simply too heavy. Helium only lifts approximately 1.5 grams per liter and I would need a 150+ liter intertube to accomplish what I'm aiming to do. Hydrogen is too dangerous a gas to work with. 

Creighton

[Greg Miller]

Not to mention that an inner tube doesn't stretch easily, and will
significantly compress the helium making it more dense. At some point
the helium filled inner tube would weigh more than an empty inner tube,
and my guess would be that'd happen before you got any positive lift.

[crei...@sdf.lonestar.org]

> Hydrogen is too
> dangerous a gas to work with.
>

That statement just means you don't know how to deal with dangerous
materials. I work with electricity daily, and occasionally with voltages
of 4160 nominal. I've had some close calls, and I've literally witnessed
a power panel explode due to catastrophic arc-over alone.

Hydrogen, by comparison, is fairly tame. Acetylene is a bit more
volatile, so I'd make my sons be at least 10 and use safety glasses with
acetylene. Hydrogen is safer than propane; just use it outside and keep
the ignition sources away from your tanks. Easy peasy. Propane is not
only flammable, it's heavier than air, so it hangs around even once loose.
Propane can suffocate you when you're outside, hydrogen just floats away.

The story that hydrogen was the cause of the destruction of the Hindenburg
is a myth, BTW. It was the aluminum coating on the ballast bags that
burned. That would have been just as bad a catastophe if the entire thing
was filled with helium.

Creighton

[Brad Luyster]

For reasonable uses, hydrogen *is* too dangerous to work with. A fireball that floats away is still a fireball, and with 4-74% flammability limits in air, it'll burn over a much broader range than propane. When a stray static spark can put you in a burn ward for a very long time, I'll call it "too dangerous," especially for what amounts to a hobby project. To dismiss those concerns as simply "not knowing how to deal with dangerous materials" is needlessly abrasive.

Creighton

[crei...@sdf.lonestar.org]

> For reasonable uses, hydrogen *is* too dangerous to work with. A fireball
> that floats away is still a fireball, and with 4-74% flammability limits
> in
> air, it'll burn over a much broader range than propane. When a stray
> static
> spark can put you in a burn ward for a very long time, I'll call it "too
> dangerous," especially for what amounts to a hobby project. To dismiss
> those concerns as simply "not knowing how to deal with dangerous
> materials"
> is needlessly abrasive.
>
>

To each his own. Eyebrows aren't particularly necessary features anyway.

Creighton