This was an entry for the James Dyson Award by a German student.
The Zundstoff Flexbag is a flexible fuel bottle that adapts to amount of fuel it is storing. Fuel bottles are normally rigid metal bottles with a fixed volume and hence take the same amount of space of space in your backpack whether it is empty or fuel.
Description by the designer (direct translation from German):
“Function
The demands on a cooker used while doing outdoor sports like hiking are completely different from those while camping. Most important: The weight and volume should be as little as possible while also providing a great extent of flexibility. Petrol stovesare quite popular in this context, since gasoline is widely available and has a high energy density. But especially the fuel bottles of petrol cookers offer little flexibility and are, due to the pump with which the fuel is put under pressure, liable to break down. If a failure of the pump occurs, there is no alternative to compress the fuel – a total failure. The adaptable fuel bottle Zündstoff Flexbag consists of a tubular formed body made of coated Cordura, which is braced by struts made of ABS. A partial elastic belt is brought into this, by means of which the bottle can be compressed. Thus, the Flexbag replaces the customary fuel bottles as well as the corresponding pumps and is therefore less liable to break down. – If necessary, the compression can also be generated by a weight like that of the backpack or your own body. The volume of the bottle can be adapted to its actual capacity by means of the tubular body; also before pouring in the fuel. Thus, in the luggage, Flexbag takes only up the room of its actual content. The product graphic makes it possible to estimate the content of the bottle and to reduce it to the desired volume before pouring in the fuel.”
