Steam?

Has anyone looked at steam as a lifing gas?  I have attached a report on this.  It's cheap, easy to make, non-flammable and recyclable.  You can capture the heat from your engine exhaust and make up the reat with a propane fired monotube boiler.  the steam condenses on the inside of the envelope, collects in the bottom and is recycles.  leaks don't matter much and if you do need make-up water you can capture it from your engine exhaust like the dirigibles and Zeppelins did.  Steam also has twice the lifting capacity of hot air and only about half tht of He and H2.

Vince Homer

Attachment: STEAM LTA.doc (994.0KB)

Yes we have considered steam as a lifting gas and I have seen the flying kettle website, which I assume is yours. We appreciate the need for the ability to vary lift. I like the idea of heating hydrogen to increase lift.

But, our current goal is to build a sort of ultralight airship kit. That way there are fewer barriers to entry like aircraft certification and pilots licences. The kit will consist of a simple envelope and a simple powered paragliding style gondola. Then each builder could add whatever engines or modifications to the kit that he wants to. It would be modular, so you can swap out your own custom components if you want to do more than make small modifications to the basic design.

This allows different people to use diffrent lift gases. I can use hydrogen and you can use steam, but we share many common parts and benefit from the economy of scale of a larger production run.

I like the idea of using steam to increase the volume of another gas, like hydrogen or air. A composite solution would probably reduce the condensation on the walls and the weight penalty that comes with it. If you want to see what has been said about steam on this forum, there is a google search bar near the top of this page that will pull up threads where steam has been discussed.

Oh, and welcome to the forum! There is also a thread for new people to introduce themselves if you are interested. http://smallblimps.lefora.com/2009/06/23/tell-us-about-yourself-your-interests-your-skills/page2/#post35

Thanks for the reply.  The flying kettle web site isn't mine.  I ran across it a while ago.  As a several decade member of the Lighter than Air Society I have been an airship watcher for a long time, but never a builder.  The concept of a starter platform makes a lot s sense as I'm sure that's the stumbling block for many.

I had also thought of using steam to augment a hot air system.  The Flying Kettle guys inflated with steam which required a giant steam generator, much larger that that required for flight.  If you inflated with hot air and then introduced steam the ground generator would be eliminated.  It's interesting that the gas temperature for a steam balloon seems to be slightly lower than that of a hot air system (212 F vs ~225 F) which would actually reduce the lift of the hot air system intil the steam percentage increased.  I think this would be a very easy concept to test with a model size envelope. 

Right now I'm in Saudi Aabia for a few more months and away from my shop.  Maybe a project for this summer.

Vince Homer

Even at that lower temperature, saturated hot air will be lighter. That well help the envelope last longer too. They can run hot air balloons up to like 250, but they don't because it wears out the bag faster. 

Maybe by the time you get back we will have starter kits available. Not all that likely, but its good to have goals...

I've looked into steam and it has a few major stumbling blocks.  For one thing, the amount of energy requried to produce the steam and to recycle the condensation is far more than even a hot air balloon requires, and that's saying a lot since hot air balloons are also energy hogs.   There is also the issue of insulating the envelope enough so that the rate of condensation is not excessive.  You start losing the benefit of the extra lift you gain over hot air from the extra weight of the envelope required for using steam.   Producing enough steam to lift even a small one person balloon requires a substantial amount of water as well.  Trying to make a portable operation for a steam balloon would require hauling around a substantial weight in water, fuel and a boiler system.

The German HeiDAS project has made the most progress with modeling steam balloons to date:  http://www.heidas.de/

The HeiDAS design is basically a double envelope Rozier type design, with the inner balloon being the steam bag and the outer balloon being hot air.  I think they are using a very high temp envelope and surrounding the steam bag with hot  enough air to prevent condensation from even occuring inside the steam balloon.  Their working RC model is impressive for its small size.