The reservoir is a single fold bellows. It's made in Plywood.
The top plate is ballasted by weight which assure the good pressure.



The edges of ribs are countersunk
I stick the skin on each side.




The plate and the reservoir are held in the correct position while I installed the ribs.
In this position, the angle of ribs has to be 90 °




And I glue the gussets


The safety valve


Curtain valve side


windtrunks side


Pulley mechanism for the curtain valve


bellows inflating


Bellows seen from the outside


Bellows seen from the inside
We can see in the foreground the safety valve, at the bottom the curtain and the helix of the blower.