Technical drawings are made for engineering machines…

…but not for interaction between machine and human! It’s probably one of the hardest points in airplane design: How is the crew going to fit in the plane? Does it feel good to sit in there for hours? Do I like the sitting position? Am I going to have good acces to controls and instruments? How’s the view?

One way to avoid having to answer those questions before hand is providing as much place as possible. However, this increases drag, and even more important here, weight. With at most 120 kg empty weight on my dispose, this approach is obviously a no go. The other is building a mockup and letting various experienced pilots judge by entering, sitting-down and exiting the mockup. This is much better than any fancy „µ-cron“ precise CAD system and the reason why I invest time in making an elaborate mockup.

The last week we tried out the mockup without having really the inner boundary of the cockpit. Thus, I produced this boundary by laminating several layers of wood strips. It is actually a three dimensional curve in space, but I decided to approximate the shape by using two plane curves joining at a kink. Dispite all my prior CAD drawings, I decided—after three persons sat inside—to move the cabin 50 mm upwards. Getting out of the plane was too hard and head space was low. This is much better now!

 

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Mockup gets a seat

Finally, I managed to build a simple but adjustable seat for the mockup:

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It’s simple but comfortable. Before I installed it, I used to sit on it at the terrace taking a small nap. Maybe it’s too comfortable?! Anyway, the sitting position is fine and the cabin shape does not need to be adapted to fit the pilot in. Pedals and controls are next!

Always start with a mockup

The aerodynamic design ir practically done and it’s time to start with the full-sized airplane. But before I put my hands on it, a mockup of the center section is needed to decide on how to design the cabin. A cabin is not needed in an all-wing, at least from the point of view of aerodynamics. Nevertheless, you need to sit somewhere, unless you decide to use a prone position, like in the Horten IV. To be honest, I prefere a more conventional sitting position.

After getting some ideas and letting a friend cut wood for me, I started to build a full-sized mockup to get an idea of the sitting position, instrument and control positions, and not to underestimate, how the view out of the plane is going to be. Essentially, I decided to build the mockup of two spars and wooden ribs. It will be covered with Ceconite Superflite 104A. Surely not he cleanest build, but it should do enough to get a feeling of how it’s going to be piloting the Schneewittchen.

There is still a lot to do. Anyway here are some pictures:

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