I have started a new design with working title “project H2” (=Hindenburg 2). As the name suggest, it will be rigid hydrogen filled airship model. First airship design was named “KAPR 1”, witch means “CYPRINUS 1” in cz. Title was affected by the basic shape reminding its proportions.
Basic idea is to use weather balloon as the gas bag. Spherical weather balloon is formed by aluminium shell to required shape. This make the general limitation for dimensions. Optimal ratio of main diameter and length is 1:4 (in original design of WW2 airships was even 1:5). In this case it is counted with ratio 3:5.
So it is assumed bigger air resistance and therefore lower efficiency of flight in straight direction. On the other side I suppose better controability influenced by shorter distance between the control wings and the center of gravity.
Propulsion will be made of 2 electrical engines on sides. Gondola with all equipment will be mounted on the bottom. Axial position of gondola will be calculated in dependence on location of center of gravity and center of buoyancy.
Precalculation shows that it will be quite big whopper – main diameter 2,6m, length 4,4m. In this stage of design it is planned with 14,3 m3 of hydrogen which gives 15,9 kg of total lift. It looks like a lot of lifting force, but for now the weight reaches 10,9 kg (shell+balloon+engines+wings) so it remains 5 kg only for the rest (servos, battery, equipment).
As the volume will be determined by the shell shape and the lifting force will be constant, it will be needed to have some weight reserve. This reserve will be compensated by ballast to equalize the lifting force and gravitational force.
And now back to the drawing board…