Laurent Besset’s solar-balloon site starts with a delightfully old-web proposition: black plastic, sunshine, Archimedes, and enough patience can get something airborne.
A solar balloon is an ultralight hot-air balloon whose envelope absorbs solar radiation instead of being heated by a burner.
Besset’s English section explains the principle, materials, construction, tethered and free flight, experimental uses, historical examples, and several scales of balloon.
The numbers make the concept immediately tangible.
The site says a four-meter balloon can lift about 2 kilograms, an eleven-meter balloon about 55 kilograms, and a 14.5-meter balloon about 120 kilograms under suitable conditions.
At the tiny end, there is a mini-balloon made from black plastic trash bags, adhesive tape, and ordinary household tools that can lift roughly 80 grams.
A hobby site with engineering underneath it
The archive is not just a set of pretty balloon photographs.
It includes discussions of thermal radiation, polyethylene film, buoyancy, materials, construction methods, free-flight technique, payloads, radio-amateur uses, educational experiments, and reports from actual launches.
One page points to a June 2000 flight in Grenoble. Other material reaches back to a 1982 Pif Gadget feature involving a small cylindrical solar balloon.
The larger site describes more than ninety pages, over eighty drawings, and more than 160 photographs across its multilingual material.
Its presentation is also a period artifact.
There are separate French, English, and Spanish sections, links to a Yahoo Groups solar-balloon community, hand-made navigation graphics, and badges proudly announcing conformance with XHTML, HTML, and CSS standards.
That last part is worth remembering. There was a period when putting a validator badge on the bottom of a page felt like bolting an inspection plate to something you had built yourself.
CacheRat’s 1,967 Ancient Web Domains research list contains technical hobby sites like this because they often preserve the practical middle layer between a scientific principle and somebody actually trying it in a field.
The sun provides the heat.
The website provides everything else you forgot to ask before buying the plastic.