The ULF-1 single seat foot-launched sailplane was designed by Dieter
Reich and constructed by Heiner Neumann of Germany. Designed for
ridge soaring and marginal thermal currents (Microlift), it has
full three-axis aerodynamic control. Its first flight was in November
1977; its first public appearance was in August 1978 at the 3rd
International Hang Glider Meeting at the Wasserkuppe, the historic
German soaring site.
Since that appearance different pilots on a number of ULFs have
accumulated many hours of flight time. The prototype alone has more
than 150 hours total flight time in 200 flights, most of them starting
More than 40 ULFs are believed to have been completed and flown.
Fifteen ULF-1s are in operation in Germany. The longest flight lasted
six hours; the maximum distance achieved 140 km. Both of these flights
started with a foot-launch.
In July 1980, the ULF-1 design received an airworthiness certificate
issued by the German authorities, after all required calculations
and tests had been provided by the designer. In 1983 the Australian
authorities gave approval for the ULF-1 to be built and flown in
Australia. ULF-1 is, as far as we know, one of the best-performing
foot-launched aircraft to date.
The aircraft can be foot-launched from slopes of more than 15 degrees
even at small wind speeds. The pilot supports the weight of the
aircraft on shoulder straps and uses the side stick for lateral
control. The self-launch is rather simple and does not require any
special skill. As the pilot starts the take-off ground run, the
elevator stick should be in slight nose-down position to lift the
horizontal tail. The moment the pilot feels a pronounced seat pressure;
the control stick is pulled back until the aircraft lifts off. After
take-off the pilot retracts his legs and puts them on rudder pedals.
A sliding slat-type construction behind the pilot's back can be
released in flight to provide a seat.
Because of a low sink speed (0.8 m/s at max. take-off weight) and
its good manoeuvrability, ULF-1 is sensitive to marginal thermal
conditions. The best L/D of 16:1 is at around 55 km/h (about 34
mph). To reduce the aerodynamic drag of the fuselage, hinged doors
have been fixed to the front superstructure of the fuselage. They
are kept open during take-off ground run and closed manually after
lift-off. For "record-breaking" flights a closed Plexiglas
windscreen is recommended.
It is estimated that both measures, the "landing gear"
doors and the windshield, improve the L/D by ten to fifteen per
cent, resulting in an L/D of 18. Since this glide-performance is
also at a relatively high speed, the average cross-country cruising
speed, including time for circling is at least fifty percent higher
compared with conventional hang gliders.
Landing the ULF-1 is done on a nose skid located beneath the pilot's
seat. The airplane can also be launched by bungee rope (down hill),
winch, car and air tow.
The three-axis aerodynamic control greatly reduces the pilot's
workload compared to a conventional hang glider with its two-hand
yoke bar, and frees one of the pilot's hands.
Dynamic pull-ups to about 20 degrees result in a smooth nose-down
movement after the wing has stalled. In turns or in turbulent air,
there is some wing drop in a stall. Recovery is properly and promptly
achieved with opposite rudder. The loss of height is usually less
than 10 meters (30 feet).
For sailplane pilots there will be no problems flying the ULF-l.
However, experience with conventional hang gliders is not sufficient
to handle the aircraft. At least some solo flight experience in
conventional gliders is recommended.
ULF-1 is specially suited for selfbuilders. The basic construction
materials are spruce, birch plywood and balsa wood. The airframe
is covered with doped fabric. For hinges, fasteners and fittings,
aluminium, steel sheet and fibreglass/resin are used. Steel tubes
are employed only for the control stick, control parts in the cockpit
area and rudder drive.
The ULF-1 prototype is equipped with a ballistic recovery system
for both pilot and aircraft, located immediately behind the main
bulkhead and activated by means of a mechanically released pull-out
For road transport, the two-piece wing can be detached. In addition,
the horizontal tail can be removed. The aircraft can be taken off
a trailer and assembled in about ten minutes.
A plan pack is available comprising of:
A complete set of 31 blueprints (14 sqm) most of them are full
scale, including full scale computer generated lines for wing and
A 37 page construction manual (with sketches) including a list
of materials with their American, British and German designations,
in addition many photographs, showing construction details.
An inspector's test and check list.
An 18 page flight-/operation manual.
A cut-away drawing (A3).
All descriptions and manuals are in English language (metric units).
The cost of materials amounts to about EURO 2500. The aircraft
can be built in about 1000 hours. Kits or materials are not supplied.
In Germany all ULF-1 airplanes constructed under license are considered
airworthy and permitted to be flown, provided the following requirements
1. Construction supervision by an authorised inspector, according
to the check-/test instructions as written in the ULF-1 construction
manual, followed by a detailed final inspection.
2. Condition inspection by an authorised inspector every two years.