This was built by German firm Hercules, but marketed in some countries (including the UK) as DKW. Raleigh Industries (the bicycle company) owned the rights to the name Hercules is some countries, hence the change.
It had a nominally 294cc single rotor Wankel engine built by Fischel and Sachs, which I think originally had been made for a snowmobile. As part of the deal with NSU (owners of the rights to the Wankel engine) the engine was limited to 30 hp, so the bike wasn't that powerful.
Early versions had petroil lubrication, but later had a separate oiltank mounted above the rotor and covered with an metal plate.
At the time I thought about one, I had only read about them in magazines, and this was the era when Wankel engines were 'the next big thing'. However, as we now know, that didn't work out as planned. A few years later I saw one in a bike shop and to be honest, the quality of equipment and finish were pretty poor.