Pay attention!
The position of the spoilers has a big impact on the capacity of the air inlet. The picture below illustrates this for the Flash 3300.  Therefore Tulderhof advices to calculate with 10 Pa under pressure..

Technical specs
The numers mentioned above are valid when the spoilers are in the "normal' position.

The F-3300 is made of plastic and has a standard size. All other Flashes are made of  the highest quality plywood and therefore available in many sizes.