EWR VJ 101

https://en.wikipedia.org/wiki/EWR_VJ_101

The EWR VJ 101 was an experimental German jet fighter vertical takeoff/landing
(VTOL) tiltjet aircraft. VJ stood for Versuchsjäger, (German for "Experimental
Fighter"). The VJ 101 was one of the first V/STOL designs to have the potential
for eventual Mach 2 flight.

During the 1950s, as various nations took an interest in developing VTOL-capable
aircraft, the German Federal Government issued a request to the nation's
recently revived aviation industries for them to study possible designs for such
aircraft. In response, in 1960, German engine manufacturer MAN Turbo commenced
work on a suitable engine in close cooperation with British engine manufacturer
Rolls-Royce Limited. Likewise, aircraft firms Heinkel, Bölkow and Messerschmitt
performed their own studies before coming together to form a joint venture
company, EWR, for the purpose of developing and manufacturing their design for a
supersonic VTOL fighter aircraft, which was soon designated as the VJ 101 D. The
Federal Ministry of Defence (BMVg) were suitably impressed to place an order for
a pair of experimental prototypes to be produced to demonstrate the design's
capabilities.

A pair of prototype aircraft, collectively known as the VJ 101 C and
individually known as the X-1 and X-2, were constructed and participated in a
five-year test program. The intention was for the VJ 101 to eventually be
developed as the basis for a successor for the German Air Force's inventory of
American Lockheed F-104G Starfighter interceptors. However, development of the
VJ 101 C was greatly complicated by the changing requirements of the BMVg, who
decided to transform the aircraft's envisioned mission profile from the
interceptor role to a more general fighter instead, greatly changing the
performance requirements for it to fulfil. During 1968, development of the VJ
101 was ultimately cancelled.

The VJ 101 C featured an electronic flight control system, widely known as a
'fly-by-wire' arrangement. It was realised that it would be of critical
importance to maintain controllability during the hover phase of flight, in
particular the responsiveness of the engines and augmentation of the aircraft's
stability. Control systems, developed by American firm Honeywell and Germany
company Bodenseewerk, performed various functions across the flight regime of
the VJ 101 C, including attitude control during hover and the transition from
hover to horizontal aerodynamic flight. Two-channel control systems were
initially used, but testing revealed the need for three-channel control systems
to account for instances of hardover failures. Upon the switch to three-channel
control systems, this enabled the system to be used through all flight ranges
with thrust-vector control; the first such system to be developed. After the
programme was no longer being pursued as a successor to the F104G Starfighter,
it was retained as a development programme to explore and prove its flight
control concepts.

In order to test the propulsion concept, EWR produced a test rig, called the
Wippe (seesaw), during early 1960. The simple device incorporated a rudimentary
cockpit fixed upon a horizontal beam, which had a "lift" engine mounted
vertically at the centre, for the purpose of performing preliminary single-axis
tests of the control system. A later "hover rig" was assembled, which had the
skeletal fuselage of the VJ 101C along with a total of three Rolls-Royce RB108
engines installed in the approximate positions that they would occupy in the
final flight-capable version. The small engines each could generate a maximum of
9.3 kN (2,100 lbf) thrust, enough to lift the test rig. Starting in May 1961,
initial testing was conducted from a telescopic column, in March 1962, the new
rig conducted its first "free flight" successfully. Additional tests performed
with a cloth "skin" to simulate the fuselage and wings proved to be successful
as well, having demonstrated satisfactory control throughout all seasons and
weather conditions.


Role
V/STOL fighter

Manufacturer
EWR

First flight
10 April 1963

Retired
1968

Status
Cancelled

Number built
2

Developed from
Heinkel He 231

On 10 April 1963, the X-1 made its first hovering flight. On 20 September 1963,
the first transition from hovering flight to horizontal flight took place. The
X-1 was first publicly exhibited at the May 1964 Hannover Air Show. The VJ 101C
X-1 flew a total of 40 aerodynamic flights, 24 hover flights and 14 full
transitions. In the course of these tests, the sound barrier was broken for the
first time by a vertical takeoff aircraft; however, on 14 September 1964, a
defect in the autopilot caused the X-1 to crash, sustaining some damage as a
result. On 29 July 1964, the VJ 101 C flew at Mach 1.04 without use of an
afterburner.

On 12 June 1965, the second prototype, X-2, conducted its first flight. On 22
October 1965, the X-2 performed a successful transition with a new autopilot
system installed. The tests were subsequently continued with X-2, which in
contrast to X-1 was fitted with afterburners. However, the project was cancelled
in 1968. The proposed VJ 101 D Mach 2 interceptor was never completed. Today, VJ
101 C X-2 is on public display at the Deutsches Museum in Munich. While the VJ
101C did not proceed to production status, various other projects of the era to
develop supersonic-capable VTOL fighter aircraft, including the Mirage IIIV and
the Hawker Siddeley P.1154 (a supersonic parallel to what would become the
Hawker Siddeley Harrier, a subsonic VTOL combat aircraft that reached
operational service), ultimately met similar fates. The Harrier jump jet and,
substantially later, the Lockheed Martin F-35 Lightning II, has since
demonstrated the potential of VTOL fighters.

Specifications (VJ 101C X-1)

General characteristics
Crew: 1
Length: 15.7 m (51 ft 6 in)
Wingspan: 6.61 m (21 ft 8 in)
Height: 4.1 m (13 ft 6 in)
Max. takeoff weight: 6,100 kg (13,420 lb)
Powerplant: 6 × Rolls-Royce RB145 turbojets, 12.2 kN (2,750 lbf) each

Performance
Maximum speed: Mach 1.04 achieved




*