Q Branch - Hafner Rotachute
Hafner had created his first aircraft design in Austria in 1929, a helicopter.
He came to England where he proceeded to develop a somewhat successful gyroplane.
He continued with other designs, some tendered to requirements of early Air Ministry
By 1940 he was in charge of a rotorcraft team at the Airborne Forces Experimental
Establishment at Ringway, Manchester, where the idea of using a rotor instead
of a parachute to more accurately deliver personnel into enemy territory was developed.
On October 3, 1940, work began on what would become the Rotachute; practical
testing began only eight days later with 3 ft. (0.91 m) rotor blades attached
to lead ballast. Test drops from a Whitley bomber showed that, whilst the
models lacked strength, a properly ballasted rotor could achieve stable flight.
A new model with two metal blades and a total weight of 5 lb. (2.26 kg) was built,
and launches from a Whitley on October 16th and from the interplane struts
of a Tiger Moth on November 7th were only partially successful, but on
November 15th a good descent from a Tiger Moth was achieved.
next step was to build a larger model with 10 ft (3.05 m) rotor span and weight
of 1000 lb. (45.3 kg). After stability tests on the ground on February 19,1942,
the model was successfully launched from a special structure on the interplane
struts of a Boulton Paul Overstrand bomber, near Manchester on March 14.
The model descended from 2,000 ft. (609.6 m.) at 1,500 ft/min (7.6 m/sec).
Meanwhile, from late 1940, Hafner had been working on the designs of a full-scale
Rotachute. One concept was to carry several in a rail on the top of a modified
troop-carrying aircraft and launch them rapidly, one after the other, from the
tail end, to land in as tight a group as was required.
The Rotachute was designed to fit criteria of simplicity, light weight
and reliability. It comprised a steel tube frame to seat the pilot, a two-bladed
rotor with freely flapping blades, and a rubber mounted skid. The rotor hub was
also rubber-mounted, to dampen vibration and to function as a control hinge. The
fuselage was open at the front. A tapered fairing behind the pilot stabilised
the craft, and this was made entirely of rubberised fabric, with no framework,
and was inflated to shape, with the intent of minimising stowage space.
was by means of a single stick fixed to the rotor hub. Turns were simply a product
of banking. As designed, the Rotachute had a weight of 50 lb. (22.7 kg)
and a useful load of about 240 lb. (109 kg.), which might comprise the pilot,
his parachute and a Bren gun Mk.1 with 300 rounds.
The rotor diameter was 15 ft. (4.57 m.), making it the smallest man-carrying vehicle
capable of controlled flight ever built to that time. Contracts for Rotachute
production were placed. Before flight trials began, tests were made with rotors
and a complete unit fixed to moving vehicles. Early in 1942, the first flights
Two trials at Ringway in February ended with heavy landings, the craft overturning
and breaking the rotors. A third run on a longer runway at Snaith was a little
better, and it was decided, at least for training, to fit a three-point wheeled
undercarriage (rather than a jettisonable trolley), and aft stabilising fins.
This required an extension of the tail fairing, which could no longer retain strength
sufficient to avoid fouling the rotor without additon of a frame.
A light frame and tailplane were added, the whole being inflated by ram effect
from forward movement. This, the Rotachute Mk.II, first flew in late May,
1942, towed behind a Jeep for about 15 seconds of flight. Further tests led to
satisfactory ground-initiated flights of two or three minutes. Work now began
on the Mk.III.
Tests began at Ringway of the Mk.III in June 1942, with towed flights of around
four minutes ending in controlled landings. A totally free landing followed. The
Rotachute was then towed behind a Tiger Moth until it, but not the
tow aircraft, achieved takeoff. Further flights led eventually to towed air launches,
the Rotachute reaching altitudes of up to 3,900 ft. (1189 m.), and reaching
93 mph (150 km/h) and flight duration of up to 40 minutes.
Subsequent tests using the Rotachute were concerned with development of
the Rotabuggy, a Jeep fitted with a rotor
and tail unit in much the same configuration. The Rotachute was developed
to a Mk.IV, with vertical fins added to the tailplane.
The Rotachute was found to be a fairly simple machine to fly and to land
in a restricted area. However, the operational needs for which it was designed
never materialised. Rotachute experience did provide a basis for much of
today's knowledge of light rotorcraft.