The Items we Need to Make....

Here is a diagram of the various parts for the first Steam Balloon:





(not shown here are the ground boiler, which is of course absolutely essential, nor any flight boiler, since none is required for this "dribble" type of flight)

(one or more relief valves for envelope venting upon overpressure may be deemed advisable)

The envelope, seat, and load frame are conventional and self-explanatory.

The "contraption" at the base of the envelope serves several functions. It allows condensed water to be drained out and discharged, while preventing the escape of the steam lift gas. Also it functions as a diffuser when the envelope is being initially charged with steam. In detail, if our 600 cubic meter envelope is to be filled with steam in, say, one hour, then the amount of condensation that is to be expected during that hour, during the filling, will also be about 600 cubic meters of steam (we suppose, approximately). Thus we need to introduce a total of 1200 cubic meters of steam into the envelope in that hour, which is about 330 liters per second. That is quite a lot of steam! If the supply tube is 15 cm in diameter as appears reasonable, then the steam will be traveling through it at about 25 meters per second. If such a strong steam jet is allowed to play directly on the material of the envelope it will certainly remove the silicone coating fairly quickly and make the fabric porous. Therefore we need to provide a diffuser to spread out the steam flow, so that (hopefully) its speed drops to a whisper. By the way, although not shown, there will naturally be a quick-release valve for disconnecting the steam supply hose once the envelope has been filled. In fact, there will have to be quite an apparatus of steam piping and control valves, in order to be able safely to shut the steam supply off, reconnect it, etc. without boiling our hands... even though this is not pressure steam, the flow rate is great enough to command some serious respect!

We also need fairly sophisticated arrangements for handling flight ballast. Initially, as explained on the flight modes page, the weight budget for our current envelope will allow us to take aboard about 200 kg of ballast - conveniently, water. This will be carried in the ballast bag. Although of course we do not yet know the exact figures, we anticipate that perhaps, when flying, our Steam Balloon will have a steam condensation rate of about 8 to 10 kg/min. This will mean that the gross lift will also diminish by about 10 kg/min, so it will be necessary to discharge about 10 liters/min of ballast, to stay neutrally buoyant. (And thus the maximum flight duration for this "dribble" flight mode will be about 20 minutes; then the ballast will run out!) The pilot will use the control valve to vary the rate of ballast discharge. Just how delicately he will be able to control the rise and fall of the balloon, remains to be seen.... yes, I know, getting back down here from up there may prove to be the Achilles heel of this setup.... I think this may have been a problem with the manned "Bulle d'Orage" described in the Prior Art section of this website..... Anyway, we'll have a go.... Better take a parachute along!

Back to the top page for the details of how we are getting along with actual manufacture...




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