Skoda Works Rocket Experimental Station at Pibrans - new and unknown aircraft development called ROTT

[Dazzle]

In an Interrogation report Ref No SAIC/38 under the Heading "Aircraft Development", 3. June 1945, page 11, available at "NAID: 57348319" at NARA, i.e. https://catalog.archives.gov/id/57348319 the following aircraft development is stated by a person called Nils Larrson who had worked at Skoda Works Rocket Experimental Station at Pibrans together with Rolf Engel, the famous rocket engineeer:

"Aside from the jet aircraft developments (The TL - Turbolader; R-Jaeger - rocket fighter; the Saengerches Strahlrohr device), source claims that his group at the Pibrans Experimental Station started work on a new aircraft, called the ROTT. This was to be a double-purpose aircraft. For speeds up to 700 m/sec an OTTO motor and propeller was to be used, while for higher speeds a liquid-fuel rocket device would take over, with the OTTO motor acting as supercharger and compressor for the rocket device. Sources claim that by using the rocket device as auxiliary starting device for the aircraft, an OTTO motor of smaller efficiency could be used."

My question to the archives specialists is as follows: Can you direct towards files in any archives you know of, which hold more detailed information about the developments at Skoda Works Rocket Experimental Station at Pibrans, headed by Rolf Engel on the end of WWII? Specifically the aircraft development called ROTT would be of great interest to me.