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SIK Mylar Magic

Mylar Magic double skin balloon

 

 

 

 

 

 

 

 

This is quite a different system in a number of respects. For one it is double skinned that is it is a balloon within a balloon and secondly it is made out of a thin polyester film rather than a woven fabric. It has been designed to fit within the FAI AX-2 category and was used to break the AX-2 world duration record in February 2004.


This record was not completed without some re-engineering work to both balloon envelopes and highlights some of the dangers of building and operating 'experimental' aircraft. During the inflation for the balloons first flight the acrylic transfer adhesive that was used to stick the envelope panels together failed in the cold temperatures (-27oC). The failures were confined to a couple of small areas so a flight was conducted at low level for about an hour to prove the systems performance. This flight was ultimately terminated well short of the record mark.

 

Subsequent research revealed that acrylic based adhesives are generally only acceptable for use down to about -10oC. The specification sheet for the transfer adhesive used on this project states that it is good down to -30oC, this figure appears to be overly optimistic. Reinforcing of all of the envelope panel seams was required before further flight and was effected using a silicon adhesive based cloth tape. Following this reinforcement work the balloon performed superbly and broke the world AX-2 duration record.

 

Mylar balloons are not new to Australia or to other parts of the world for that matter. Much of the early development of balloons was conducted  using film balloons, in Australia this work dates back to the days of the Aerostat Society in the early 60's when a balloon called Archimedes was made, this was followed shortly after by Phil Kavanagh's Little BearGrahame Wilson's website has a good rundown on the early history of balloons in Australia including some of the early film balloons. which flew some 170 hours before being retired.


Film balloons are more fragile than fabric balloons hence they are not generally used for recreational or commercial ballooning operations. Mylar however has much better thermal performance than a similar weighted woven fabric which makes it particularly good for high performance / short operational life balloons.

 

From a construction point of view a film balloon is very easy to build but you need to have at least 2 people on hand for almost all of the taping operations as the film tends to be difficult to maneuver and impossible to join on your own. About the only tool you need is a pair of scissors or a sharp knife. In contrast a fabric balloon can easily be built as a solo operation but you need to have at least one and probably 2 specialized sewing machines, a swaging tool and the skills to use them.

 

There have been several reproductions of this balloon made around the world. Pierrick Duvosin was the first to refine the design and very successfuly broke my AX-2 duration world record. There have been a few not so successful as you can see from this you-tube video.



 

 

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