Translated that letter the best I could:

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Karl Peter, Dipl. engineer

Dessau (Anhalt)

Flurstraße 24

 

Dessau, May 1948.

 

At

 

B e r l i n

============

 

Arrived: Offer for new aircraft construction.

In the attachment, I present you with the design of an aircraft, the shape and layout of which meet the needs that can be placed on an improved helicopter.

In principle, this is a screw-top aircraft that can be switched to a normal tandem aircraft in the air. In this case, all good properties of normal aircraft would be retained in the travel position, while on the other hand the great advantages of helicopters during takeoff and landing would not be lost. The main question, whether the full stability of the aircraft is maintained during the changeover, can be answered in the arithmetical way. The stability can be determined empirically on a model without any particular difficulty, whereby the most favorable dimension ratios can also be determined from flight experience.

If you are interested in my offer, which for the time being only shows the basic arrangement, I would be happy to lead the experimental work and take over the further development of the object.

I ask for your suggestions.

 

Respectful

Karl Peter

 

Attachments:

4 sheets of text

4 sketches

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So, it seems to be an early example of a stoppable-rotor design, in which the rotor-wings can transition into fixed-wings. Very interesting find!