On the quest for personal blimps, I would recommend pursuing hot air as the lift gas over helium or hydrogen for two reasons: portability and storage.

The primary drawback to gas blimps from a cost standpoint is the hangar requirement, which requires a large structure that will likely be more costly than the blimp itself to construct. Sure you can tether a blimp on a mooring mast short term, but you can't leave it hanging outside through storms, the winter etc. and such continual exposure to sunlight would no doubt shave years off the life of the envelope.

When you stop and think about what you would actually want to do with a personal blimp if you had one, you might realize you would probably want to do the same thing the hot air balloon people are doing-- which is take it all around the country to scenic areas and fly it. This is where the portability issue comes in. A gas blimp can not be deflated and inflated without incurring great cost, so you would actually have to fly it to the places you wanted to see. This takes a lot of logistics to pull off, not to mention a ground crew, portable mooring mast and continual attention to the weather. It would be such a hassle trying to go from say Florida to the Grand Canyon and back that it would not be worth the time and expense.

A hot air blimp requires no hangar and can be towed around the country in a small trailer. It incurs no expense when not in use, unlike gas blimps that continually hemorrhage money in the form of leaking gas that must be replaced. So for the weekend blimp warrior, hot air makes more sense. If making your own blimp envelope, the hot air type is also easier to produce since you don't have to worry about leaks and nylon fabric is less expensive than custom composite films. The primary down side to hot air is the performance characteristics compared to a gas blimp, which is more limited in speed, duration aloft and the kind of weather it can be flown in. But for a non-commercial operation where you don't HAVE to fly on any given day, joy rides are only an hour long and you're not trying to maintain position over a stadium, this is less of an issue. The current designs for modern hot air blimps also have more room for improvement, so the performance gap could be closed a little more.

wikipedia<<<The aluminium used in United States and Canada are alloys containing 92.5% to 97% aluminium, <5.5% magnesium, <1.6% manganese, <0.15% chromium and some trace amounts of iron, silicon and copper according to MSDS from aluminium producer Alcoa.[5] Alloys used include 3004, 3105, or other 3xxx/5xxx series aluminum.[6]>>>
Right, so ~5% of the can aint aluminum and that leaves a sludge in the electrolysis reaction vessel. Also, wiki says the inside is coated with epoxy resin to prevent oxidation.
Sodium hydroxide doesnt cost much but it costs. I'd rather develop an electrical source for H2 for my Personal Ultralight Dirigible than use chemical reactions.

Wow, amazing fact, how many drink cans, alum and steel are used per year?
<<Worldwide production for all beverage cans is approximately 475 billion cans per year worldwide>>>>>>>>

Originally Posted by pyronaught

but then you'd have to scrounge up about 1665 pennies for every 50 cubic feet of gas you needed!

Isn't intentionally destroying money (withdrawing currency from circulation) illegal?

Brgds, Bert

Originally Posted by Brutus1967

Isn't intentionally destroying money (withdrawing currency from circulation) illegal?

Brgds, Bert

Yes, I mentioned that in one of my posts.

this topic is H2 blimps and dirigibles. you wouldnt go to a motorcycle topic and list the advantages of a bicycle would u Pyro dude?
a dirigible and a balloon are miles apart even tho they float in air theres no comparing them.

Originally Posted by Navigaiter

this topic is H2 blimps and dirigibles. you wouldnt go to a motorcycle topic and list the advantages of a bicycle would u Pyro dude?
a dirigible and a balloon are miles apart even tho they float in air theres no comparing them.

A hot air blimp is not a balloon. I only mentioned hot air balloons to illustrate how pilots leverage their portability. A hot air BLIMP would have that same degree of portability, but without the lack of directional control inherent in a free balloon.

Back onto the subject of hydrogen-- what would really be ideal is if the population could be cured of its unfounded hydrogen phobia and switch to using hydrogen for party balloons. It is absurd that people drive around with 20 gallon tanks of flammable liquid under their cars or pump an equally flammable gas into their homes for heating or cooking, but cower at the thought of isolating a cubic foot or less of hydrogen in a completely sealed bag. The reason you can't easily buy hydrogen the way you can oxygen, propane or acetylene is that it burns at such a low temperature that it can not be used for welding applications. If hydrogen had a bigger demand, the price would drop and finding it would be easy. Getting the public to convert over to using hydrogen for party balloons would accomplish that, and also preserve helium for the full size blimps where it is really needed. The only real health risk would be the occasional dope who sucks in the air from a hydrogen balloon with the expectation of talking like a chipmonk afterwards. I'm not sure what the ramifications of taking in a lung full of hydrogen is, but since it is not an inert noble gas like helium, I'm guessing it would be bad.

Edit: maybe not-- apparently divers have used hydrogen and oxygen as a breathing gas for deep dives:

http://en.wikipedia.org/wiki/Hydrox_%28breathing_gas%29

I was a tech diver years ago and we always used helium to dilute the nitrogen and avoid narcosis, I've never heard of anyone using hydrox but apparently it's been done without ill effect. That is on deep dives too, where the outside pressure results in a much higher concentration of gas in your lungs. So if they survived repeatedly breathing that for hours without any problems, one breath from a balloon would be fine. Thus, no negative side effects whatsoever to switching party balloons over to hydrogen.

Originally Posted by Gilbert Griffith

I have made hydrogen balloons over many years with no problem explosions.
My generator uses two 60 liter drums, but I have used 20 liter drums and 200 liter drums when different amounts of hydrogen were required. The first drum contains scrap aluminium (beer cans) and is charged with sodium hydroxide solution (drain cleaner flakes from the supermarket, mixed with a couple of liters of water)
Once the hydrogen is being produced, the lid is screwed on and the gas then leaves the first drum through a pipe that goes to the bottom of the second drum which is half filled with water. Taps on the top are used to fill balloons. Every effort is made to keep air out of the system.
My 44 gallon drum setup had three taps so that three people could fill balloons at once.
Everything is done outdoors with no flames or electrical devices nearby. Never had a blow up.
The hydrogen is produced fairly quickly so you need to have everything ready. If filling balloons you need some place like a garage where you can store them until ready for use.

While reading an online article about pibals (pilot balloons) and radiosonde-carrying weather balloons several years ago, I saw--in a photograph of a concrete inflation building at a met balloon station in Africa--a large crater-like divot that was missing from one wall, about two feet below the ceiling. The caption explained that the divot was created when one of the water-immersed hydrogen generator units experienced detonation of a hydrogen/air mixture inside it, which very forcibly propelled the metal hydrogen generator into the wall. Hydrogen-filled balloons *can* be inflated and flown safely, but ^everything^--including gores and smaller portions of the envelope, as well as the hydrogen-generating or handling equipment--must be electrically connected and grounded, and:

Even then, the balloon's maneuvering valve (if it has one; Chalière balloons [cold gas/ballast-type balloons] usually do, at the top of the envelope) must be kept very clean and electrically at the same ground potential as the balloon itself. Such hydrogen balloons have burned because particles of metal oxide on the maneuvering valve, which came loose when the valve was opened or closed, ignited the gas via a phenomenon called the reverse coulomb effect (a type of static discharge that can ignite hydrogen in the presence of oxygen with very little discharge energy). Modern hydrogen-filled Chalière balloons (they are more commonly flown in Europe than in Canada and the U.S.) that are made of metallized plastic film (fabric ones are also flown) have each envelope section--as well as the valve--electrically connected in order to avoid localized electrical charge build-ups that could result in static discharges. Also:

The only truly safe way to fly using hydrogen is to have a hydrogen balloon inside a helium-filled one. The German Zeppelin company had designed the LZ-129 Hindenburg to use helium in her gas cells, inside which smaller hydrogen-filled "anti-ballast" cells were housed (because valving the helium in order to descend would have been prohibitively expensive). Ironically, the placement of the hydrogen valves--inside chimney-like fabric gas shafts inside the hull, rather than on top of the hull as in other Zeppelins (the valves' locations were retained even after the hydrogen "anti-ballast" cells were eliminated, after the U.S. Congress refused to authorize sale of helium to Germany)--may have contributed to the Hindenburg disaster, by allowing a mixture of inadequately-vented, valved-off hydrogen and air to accumulate inside the gas shafts as the ship approached the mooring mast at low speed.

Of course, you could just purchase H2 gas. It is more expensive than purchasing helium (per tank) but it's available and handily compressed. Less pure hydrogen is similarly priced... and is close to the purity of helium sold in "party packs".

It is one of the more dangerous fuels because it can burn w/ only 4% oxygen present, so gets NFPA's highest danger rating. Using it to fill party balloons presents a danger because of the heat it absorbs while expanding. Its low ignition point means even static can ignite it, if oxygen is available... about 1/10th the energy required to ignite gas and 20 times more explosive. Unfortunately a leak is also undetectable.

For manufacture or indoor storage of the craft, the structure would need to be well ventilated. H2 gas leaked less than helium from its bag, but the gas can collect in rafters (or inside the craft's outer skin).

The Hindenburg is not a good example. While the gas burned off in seconds (32 to 37 seconds by estimates) the fabric coating was possibly more volatile... sort of a giant sparkler. With the similar sized US air ships, the helium would be replaced at service intervals due to "fuel" and air contamination in the lifting cells.