The two-seat Sky-Walker Sky-Walker 1+1 was popular as an ultralight training aircraft. The airframe exists out of an aluminium-tube construction. The plane is constructed out of alu-tube covered with sailcloth.
As powersource the Sky-Walker 1+1 had a four cylinder, horizontal opposed air-cooled Limbach L 1700 EA engine. Motorgliders en ultralight aeroplanes frequently used the Limbach engines. The L 1700 EA was a perfect engine for the ultralight Skywalker with a continuo 56 HP (maximum 60 HP) and a weight of only 73 kg. The dated Limbach engine of the PH-1U9 is replaced by a Rotax 462 UL CB.
Text from: http://avia-dejavu.net/photo%20PH-1U9.htm