Between 1962 and 1965 two competitive projects were developed by the Dornier-Lorenz-Telefunken group and Bölkow-Junkers. The recoverable sounding rocket known as the Dornier Project 621 (NOT a Dornier designation) was developed on behalf of the German Ministry of Scientific Research, with the technical and scientific assistance of the German Space Research Society (GfW).
This high-altitude research rocket had a conventional cylindrical body and was intended to be powered in its production form by a 5,000 lb (2,270 kg) single-stage solid-propellent motor. The rocket itself had an empty mass of 74 kg and a gross mass of 240 kg (520 lb).
An important new feature was the use of a Rogallo flexible wing (paraglider) to bring back the rocket to its launch area after flight, for re-use. The rocket could be reused up to six times. During launch and ascent, the paraglider was stowed completely inside the rocket body. At maximum altitude the paraglider deployed and served as a wing during the descent. By means of a new technique, the rocket could be plotted throughout its flight.
Guidance commands were transmitted by eight-channel VHF-PCM system, and the rocket was steered to the recovery area by its movable cruciform tail surfaces, on a helical path of about 3 miles (5 km) diameter. Landing speed was intended to be approximately 67 mph.
Drop tests were made of the paraglider system in Sardinia in 1965 but no flights of the rocket itself ever took place, and in view of the gradual decline in costs of European and American conventional rockets and the high costs of recovery systems, the program was cancelled in 1966.
I haven't been able to locate any pictures for this program. Perhaps another forum member has something in their vaults?
You are welcome
I found additional information in "La grande aventure de l'espace", Ed. Rombaldi, 1967
The excerpt mentions another project from Bölkow-EWR Süd.
The color picture of Dornier recoverable rocket seems to be taken in a museum.
About the Bölkow-EWR Süd recoverable rocket, I found also an Air & Cosmos article.
BIG THX to Cardonet
for those picture and data, special for Do-122 in color
on Bölkow Entwicklungring Süd sounding rocket
the french Data is contradictory, one tell about two stage rocket with 5 kg payload on 80 km high,
while the other source about 20 to 30 kg up hight of 200 km.
The high-altitude rocket is shown in "Der Flieger", June, 1963, too, described as a single stage rocket.
No data about the weight of the payload is given, maximum height is described as "at least 100 km".
I've added the pictures, principally the same as in the Air & Cosmos article, but in somewhat higher res