The First Inflation - with Cold Air

Through the courtesy of another Scout Group in Hampton, we were allowed to inflate our first Steam Balloon envelope upon their recreation field (no foot-and-mouth there) . We did our first inflation with cold air in early April.

Here is the envelope flat on the ground:



This shows the load frame to which the envelope is attached via eighteen lines - one for each of the load tapes:



This shows the stage at which the envelope is half inflated:



Now the envelope is (more or less) fully inflated - but of course it won't stand, because it weighs a solid 38 kg, and the air inside is at ambient temperature and so weighs nothing, although it masses about 800 kg. Therefore the envelope remains earthbound:



This shows the vent tube at the top of the envelope, just after we pulled the ripcord and broke the string which tied this vent tube shut:



Another picture of the vent tube:



We were most satisfied with the operation of this vent tube. It everted immediately and flawlessly, even with the rather modest internal pressure we applied. When filled with steam, there will be no problem venting it when it comes time to deflate the envelope, because, with zero overpressure in the envelope, the upwards internal pressure at its crown (which gives the lift) will be about 90 pascals. Actually, come to think of it, the rapid venting upwards of 600 m3 of steam will be fairly spectacular! the resulting huge plume of mist will be much larger than the envelope itself! Instant rain....

The next stage of testing this envelope will be to inflate it with hot air and make it stand. This is not quite as easy as it seems, since we can't use a standard balloon burner to provide the hot air, because the bottom end of our envelope tapers down to a 15 cm diameter steam supply tube, and certainly can't handle a huge flame. Some other way will have to be found....





Next you can read here about making miscellaneous flight equipment....




Acknowledgements

Site map

Back to the top page...


---ooo000ooo---

This page has been viewed times since its creation...