If anyone can shed some light on this hot air airship envelope, please contact me.
A description of all known details of the airship follows at the bottom of this page.

Thanks for checking it out!

Tail fin bleed holes	Rip panel actuation lines	Inside view of nose ring
Overpressure vent flap anchor (on inside roof, 3 half-gores off centerline)	Unknown anchor point	Tail fin bleed hole detail
Nose ring	It's BIG!!!	Pressurization tube?
Superpressure burner opening?	Inside view of gondola roof area. Right is fore, left is aft.	Forward rip panel (on top centerline)
Rear rip panel (on top centerline) (Note both overpressure flap anchor points fore of rip panel)	Tail fins and rear rip panel	Nose view
	Forward rip panel actuation	The bag. 600+ pounds!

DESCRIPTION OF KNOWN DETAILS:

On the morning of July 4th, 2007, Keith Sproul and I met with a man in Harleysville, PA who bought a red and blue mystery hot air airship envelope off of eBay a few years ago. We intended to inflate it to see what we were looking at, and ideally identify what it was.

HISTORY LESSON:

The eBay seller from Southern California had no information on what it was, where it came from, or who had previously owned it. The envelope was acquired in a lot of items repossessed from a self-storage unit, and the storage location owners had not provided any information to the eBay seller who purchased the lot of items.

Way back when the auction was live, I actually considered bidding on the envelope, but the price went higher than I wanted to pay for something which might possibly be an entirely useless, unwieldy blob of smelly fabric. I soon forgot all about it, until Keith emailed me to let me know it had made its way all the way across the country and almost literally into my own backyard. Being this area's resident wanna-be hot air airship expert, of course I'd made up my mind that I would come check it out to see what it was.

INFLATION DAY:

We assembled behind a church at 7AM. Present was a small militia of helpers, which included two helicopters piloted by friends of the new airship owner. Why bring helicopters to an airship inflation? Hell, why not!

At some point, I realized that the church field we were using was coincidentally the same field I had crashed my Nail balloon into on a fun solo flight last August. One of the crew members and two of the neighbors present on this airship morning were watching last year when I piledrove my little balloon into the ground and draped over a tree in a late-morning, steep-approach, high-wind competition spot-landing. Thankfully, the entire Upper Salford Twp. Heavy Rescue Unit was as amused as I was embarrassed. I had the balloon out of the tree before they arrived.

Back to the airship... The red and blue bag sat on its shipping pallet, double-wrapped in two large cardboard boxes for protection. It was soon tipped over onto a tarp, dragged out, spread out, rip panels installed, and before long Keith's 5HP 24" inflator fan was screaming air into the small circular hole in the belly of the envelope.

With enough air to walk around inside, I began to take stock of the situation and snapped lots of pictures for archival and identification use. We kept the airship inflated for about 45 minutes, plenty long enough to get pictures of anything and everything that might help provide a clue to this airship's origin.

FINDINGS:

The envelope is approximately 155 feet long inflated (with a gore length of 174 feet), 51.5 feet in diameter at the widest point, and has five inflated tail fins in a hexagonal formation. It is missing a "sixth" fin which would be in the bottom position. There are no directional control surfaces on any of the tail fins (more precisely, no directional control at all), and the fins are also quite small and essentially useless. Each of the fins are inflated with air from the main envelope via bleed holes. There are two large velcro rip panels for final deflation, one fore and one aft, on the top centerline of the envelope. There are no rip locks.

The envelope is somewhere in the area of 650 pounds. It is made entirely of 1.9oz urethane-coated nylon and finished with Mil-Spec 5038 Type IV 1" webbing on all seams (overkill - heavy, but strong). There are circumferential load tapes on average every four feet. It was constructed with a 3/8" gauge lockstitch double-needle sewing machine using standard folded fell seams. There are 18 longitudinal gores, with seams and load tapes on the half-gores. At the nose and tail, the 36 load tapes converge at extremely heavy aluminum rings. The two rings were machined from 1/4" thick aluminum plate, 12" in diameter, and with an inner diameter of about 8". Way overkill.

On the whole, this envelope appears relatively well-built, even if perhaps not very well-planned. There are a number of places where circumferential load tapes don't match up when crossing from the blue to the red sections. It seems like each fabric color half was constructed separately and then sewn together down the two gore seams. This would explain why some circumferential load tapes don't meet properly.

A careful measurement and 3D reconstruction of the airship envelope's dimensions places the volume right at 200,000 cubic feet.

On the bottom (belly), there is one circular opening near where the front of a gondola would be. This opening is just slightly larger than would be necessary for a Raven Superpressure fan and burner unit. Approximately 14 feet aft of this circular opening is a 18" diameter fabric tube exiting the envelope which might conceivably be used for ram-air pressurization in the propulsion slipstream.

Just aft of this fabric tube is a three-foot square overpressure vent, with an internal fabric flap kept in place by air pressure against a net of webbing. There are two lines which connect the two free corners of the cover flap to the roof of the envelope, theoretically allowing for any overpressure (or vertical elongation) to automatically open the flap and let air out. In actual practice, I'm not sure how well this system would have worked, since with less internal pressure, a balloon or airship gets more vertically elongated, and vice versa.

Despite the carefully constructed belly openings, there are no attachment points for a gondola of any sort. There are no support cables or catenary curtains/lines of any sort inside the envelope. The only attachment points of any sort are in the circular opening, and these might be used for securing a Raven-type superpressure burner/fan system in place.

There are no numbers, data plates, registrations, or markings of any type anywhere on the envelope that we have found (yet).

RANDOM ASSUMPTIONS AND UNFOUNDED CONCLUSIONS:

• Based on the construction methods, materials, appearance and smell, I believe this was built sometime in the early 1980's, give or take five years. Can't realistically narrow it down any closer than that.
• This envelope appears to either never have been fully finished (due to the obvious lack of gondola attachments and no apparent steering method), or it was built for a different purpose altogether (i.e. movie prop or tethered hot air inflatable).
• Came from Southern California, so it could potentially be a George Stokes or Mike Caldwell creation, among other possible builders.
• Superman is probably looking for it.

THE CURRENT MISSION:

I'm trying to find out what it was supposed to become, who built it, and why it was never finished. Bonus points if you might know how it came to find its way onto eBay, or any interesting tidbits or stories at all related to hot air airship history.

If you think you know someone who could possibly, however remotely, have information about this airship, please ask them to check out this website and get in touch with me.

Possible Lead from Dr. Alfred Barnes:

Hello Jon Radowski:
This Ship looks very familiar.  This goes back to the late 70's or
early 80's and my memory is weak on those days, so I hope I'm right.
I believe that this was one of the last (unfinished) projects of Mike
Caldwell, owner of the now defunct Aerostatic Rainbow Wagons Balloon
Company.  I was ballooning and living in San Diego then (live in NY
now), and we were driving up to a very foggy morning launch site near
Perris.  When we came to the field, there was a very large red and
blue airship looming in the mist.  Obviously, we stopped to watch.
The scene became comical, when they somehow put a burner in it and it
gently righted.  It must have been an oversight, that there were too
few ground handling line and persons, because the hot bubble rocketed
to the tail and the while thing stood on its nose.  And it stayed
there for quite a while before slowly settling.  The crew quickly
bagged it and we went on to our passenger meeting spot – I never saw
or heard of it again.  Aerostatics was purchased shortly there after
by David Bradley, a young balloonist from Kansas who moved to the San
Diego area and set up a ride business.  Caldwell built several special
balloons: a super-pressure Great American Bank, the green and yellow
balloon that appeared on the old US postage stamp back then, and
several Coke balloons, white and red, to name a few.  There may have
been more (including this "mystery airship") that didn't get included
in the inventory of the sale, and were lost in storage.  Things may
have been chaotic for Caldwell back then.  In years past, I flew the
old stamp balloon many times.  Like your airship, it was over built (a
Caldwell trademark); heavy fabric and load lines.  So heavy in fact
that if you let it get away, it would generate an impressive decent
rate.  It was an AX 7, but in the bag, weighed as much as a 9.  I hope
I'm giving you good information, and not dead-end.  But, I can't think
of anyone else that could have built it.  I've been around balloons
and airships for a while and know others that might have more
information and better memories than mine.  If this sounds worth
pursuing, we can keep digging.