The Hindenburg Syndrome

In 1937 the Hindenburg burnt on contact with the ground and killed thirteen passengers - the only time in the history of commercial airship transportation that any paying passenger was ever injured.

The Hindenburg had individual collapsible gas cells which are very safe, but also had an outside aerodynamic covering so that any leak in any cell could provide free gas to be trapped and mixed with air.  The ship also had a mooring ground wire so that the static potential of the earth's surface was carried up to the top of the ship for discharge by St. Elmo's fire into the atmosphere - just where any mixture of released gas and air would pool - during all routine landing operations

Piccard Pleiades Balloons takes these matters very seriously.  We do not have an outer cover.  Any microscopic release of any gas is instantly dissipated into the atmosphere in non combustible proportions.  Our Piccard Pleiades model sport gas balloon has an insulating structure between the car (which may be grounded) and the support cells, so that only the minimum possible static charge can be carried to the balloon portion of the craft.

We note that standard aircraft design normally requires air to be entrained into any fuel cell to mix with the fuel vapors there every time the aircraft lowers its altitude.  Failure to have this capability would cause crushing of the fuel cell/wing structure any time there was a negative change in altitude.  You could go up, but you couldn't come down.  Future airplanes will have nitrogen generators to take the place of entraining ambient air.  The nitrogen/fuel vapor mixture will not be flammable.  Our sport balloon does not require this facility as we permit our cells to contract without entraining air.  The lifting gas remains uncontaminated and non-flammable. During the Piccard Pleiades balloon landing sequence all the gas is vented into the atmosphere at the top end of the snouts at a great distance from any source of ignition as well as well away from and down wind of the car's resting place.  The only air/gas interface is at the opening at the top end of the snout which is the last point of contact with the ground.

We absolutely believe that this balloon system is the safest aircraft ever constructed.  We utilize the very latest technology and Piccard Pleiades Balloons proprietary inventions to ensure stability in all disciplines of design and construction.   Our safety factors routinely surpass all FAA and international standards as to strength, redundancy and conductivity by wide margins.  Our flight control system is unique in its vernier control of buoyancy and effective volume without lifting gas contamination.

The Elephant In The Room

One of the greatest concerns in the sport of gas ballooning after meteorological   considerations is the danger of fire.  Even Charles Dollfus accidentally lost a balloon to fire (During the filming of "Trip in a Balloon" so the script was rewritten  to include the drama!)  There are several sources of accidental fires in balloons.  They all require a flammable mixture of gas and an ignition source.

The most often blamed ignition source (after Belarusian tracer bullets) is static electricity.  Static electricity can be generated by the contact of dissimilar materials such as wool and amber in the physics laboratory, by discharge of  electro-static charge across a gradient in the atmosphere and also by turbulence in rapidly moving gas.

The use of nonconductive fabric has been traditionally blamed as the  cause of fire.  There is no reason to use it now and we don't.  The turbulence found inside hydrogen inflation sleeves during rapid inflation causes crackling discharges, but there is never any air there.  The turbulence caused by releasing gas through a traditional clapper or teller valve has been observed to cause ignition.  The normal spark caused by the peeling of an adhesive joint such as in a standard rubber cemented rip panel has also been observed to ignite a balloon on deflation.

The use of an open appendix for automatic release of expending gas is essential.  The use of a Poeschelring in the mouth of the traditional bottom hanging appendix in order to entrain air for aerostatic stability is controversial and  is not normally used today.  The use of means to close the appendix during descents is common but may not be as effective as it should be.  The use of an appendix mounted high on the balloon to absolutely prevent air entrainment was invented in Great Britain shortly after WWI and reinvented by the neo balloon community in the U.S. in the 1950's.  Such an appendix, or "Duct" prevents any air from getting into the balloon.  As it is a soft tube, it cannot siphon air.

The duct  has a small interface between air and gas, but no source of ignition.  It has been reported that spontaneous combustion is possible and has been observed in a duct in a non conductive plastic film balloon with immediate self suffocation.  That may be suspect, but has not been recorded to cause a destructive event.

In conclusion: 

We starve the elephant.  He has left the building.

November 21, 2008 - January 13, 2009