Flightline: 72

"user314" (user314) 11/06/2020 at 11:00 • Filed to: flightline, Planelopnik, planelopnik history

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During the 1950s and 1960s, rapid advances in jet engine technology allowed designers to begin to incorporate VTOL (vertical takeoff and landing) into designs, spawning a series of VTOL strike/fighter designs amongst the Cold War powers. In addition to the UK’s Kestrel/Harrier line and the Soviet Yak-38, the West Germans, French and US also attempted to develop experimental and production VTOL aircraft, with mixed results.

The EWR VJ 101C-X1 D-9517 at the 1964 Hanover Air Show

West German aviation firms !!!error: Indecipherable SUB-paragraph formatting!!! , !!!error: Indecipherable SUB-paragraph formatting!!! , and !!!error: Indecipherable SUB-paragraph formatting!!! began investigating VTOL aircraft soon after the post-WWII ban on development was lifted in 1957. The latter two companies, along with !!!error: Indecipherable SUB-paragraph formatting!!! , West German engine manufacturer !!!error: Indecipherable SUB-paragraph formatting!!! and English engine company Rolls Royce to create a supersonic VTOL fighter. The proposal, designated the VJ 101, utilized the principal of tilt-jets, that is, the engines were mounted on the wingtips and could swivel from pointing down for takeoff, hovering, and landing, to pointing back for horizontal flight. Two prototypes were built, designated the VJ 101C-X1 and -X2, were powered by six total !!!error: Indecipherable SUB-paragraph formatting!!! engines, two in each of the wingtip nacelles and two more in the fuselage to provide downward thrust at takeoff, hover flight, and landing. The second prototype would be fitted with afterburners, allowing it to hit a projected top speed of Mach 1.8. The VJ 101Cs featured an advanced autopilot system to coordinate the various control systems during hover and conventional flight, and featured one of the first ‘ !!!error: Indecipherable SUB-paragraph formatting!!! ’ systems. The -X1 first flew in hover on 10 April 1963, with a transition flight from hover to horizontal flight occurring on 20 September. The X1 completed 40 conventional flights, 24 hover tests, and 14 full transitions, as well as breaking the sound barrier on 29 July 1964, a first for a VTOL aircraft. The X2, fitted with an improved autopilot, flew for the first time on 12 June 1965, though its test program was cut short when the program was canceled in 1968. The VJ 101 C-X 2 is currently on public display at the !!!error: Indecipherable SUB-paragraph formatting!!! in Munich.

The EWR VJ 101C-X2 on display

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The three VAK 191B prototypes

Around the same time as the VJ 101C, !!!error: Indecipherable SUB-paragraph formatting!!! and Weser-Flugzeugbau formed !!!error: Indecipherable SUB-paragraph formatting!!! (VFW) as a joint-venture to develop and produce their own VTOL strike fighter to replace the Lockheed F-104G and !!!error: Indecipherable SUB-paragraph formatting!!! ground-attack fighter. This new aircraft, the Vertikalstartendes Aufklärungs- und Kampfflugzeug (“Vertical Take-off Reconnaissance and Strike Aircraft”, abbreviated VAK) and would be capable of Mach 1.2-1.4 at medium to high altitude flight, and could be armed with nuclear weapons. The aircraft, designated the VAK 191B, was broadly similar to the Hawker P.1127 in shape, and would be powered by a !!!error: Indecipherable SUB-paragraph formatting!!! fitted with rotating nozzles. As with EWR’s plane, two lift jets would be fitted to the 191B to supplement the main engine during takeoff, landing, and hover.

Details of the RB193's nozzles

Competition from both within West Germany and from other nations, as well as changing requirements and contracting defense budgets greatly slowed the development of the 191B, with the prototypes not being completed until 1969. In the interim the program had been reclassified as experimental rather than production, and the order had been cut from six aircraft, three each of single seat and dual seat designs, to just three single seat test airplanes. The first 191B was rolled out of VFW’s plant in Bremen in April of 1969 and embarked on a 17-month flight qualification program, achieving its first hovering flight on 20 September 1971. The three aircraft completed 91 flights during the test program, which ran from 1970 to 1975. In addition to the VTOL mission, the prototypes were also used in the European MRCA program (which led to the !!!error: Indecipherable SUB-paragraph formatting!!! strike fighter), testing the future fighter’s fly-by-wire systems. All three 191Bs were preserved, with the first on display at the !!!error: Indecipherable SUB-paragraph formatting!!! , the second part of the Wehrtechnische Studiensammlung (“ Military technical collection” ) at !!!error: Indecipherable SUB-paragraph formatting!!! , and the third in storage at Airbus’ facility in Bremen.
 

One of the 191Bs under the wing of the Dornier Do31E3 VTOL transport at Deutsches Museum Flugwerft Schleissheim

The second 191B at Wehrtechnische Studiensammlung

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The Balzac V on a test stand

In 1965, the French defense firm Dassault Aviation began work on its own VTOL strike fighter design, basing it on their !!!error: Indecipherable SUB-paragraph formatting!!! fighter. The Mirage IIIV would be an enlarged variant of the III, being equipped with no less than eight !!!error: Indecipherable SUB-paragraph formatting!!! lift engines as well as a !!!error: Indecipherable SUB-paragraph formatting!!! for horizontal flight. As there were delays in the RB162 program, the first Mirage III prototype was modified with eight !!!error: Indecipherable SUB-paragraph formatting!!! lift engines to serve as an interim VTOL test bed. The resulting aircraft, known as the Balzac V, undertook its first tethered flight on 13 October 1962, with a free hovering flight occurring on 19 October. The aircraft completed a transition from hover to horizontal flight on 18 March 1963. The Balzac was involved in two fatal accidents, the first on 10 January 1964, when during a vertical descent the aircraft experienced wing oscillations that exceeded the limits of the three-axis autostabilization system’s ‘puffer pipes’. The port wing struck the ground and the aircraft rolled over because of the continued lift engine thrust. Centre D’Essai en Vol test pilot Jacques Pinier did not eject and died in the crash. The aircraft was rebuilt, but on 8 September 1965 the Balzac crashed during a familiarization flight by USAF Major P. E. Neale. The accident investigation’s results were never made public, but speculation at the time was that either there was a hydraulic failure or that the engines flamed out. The Balzac was not rebuilt after the second crash, with Dassault instead concentrating on the Mirage IIIV.

Plan-view silhouettes of the Dassault Balzac, and Dassault Mirage IIIV

The Mirage IIIV in flight

The Mirage IIIV was roughly twice the size of the Balzac, and was intended to be a fully realized Mach 2+ VTOL strike fighter. Lift was provided by eight !!!error: Indecipherable SUB-paragraph formatting!!! -1 engines, with forward thrust coming from a Pratt & Whitney JTF10 turbofan with afterburner, later upgraded to a TF106 augmented turbofan. A key design feature of the Mirage IIIV to improve vertical flight performance was the installation of movable thrust deflector doors set ahead of the lift jet exhaust nozzles. These doors would be angled 45° rearwards while on the ground, pushing both debris and hot gasses away from the aircraft’s inlets. As the engines accelerated to full power, these doors would automatically drop to a 90° position in order to provide maximum thrust. The first IIIV prototype completed a hovering test on 12 February 1965, eventually transitioning from hover to horizontal flight in March 1966. The second aircraft had an even more powerful TF306 augmented turbofan, and first flew in June 1966. On a test flight in September of that year, it reached a speed of Mach 2.04 in level flight, though it was lost in an accident on 28 November 1966. Neither of the Mirage IIIVs accomplished a vertical takeoff and supersonic speed on the same flight. The crash of the second prototype, along with mounting costs and shrinking budgets saw the Mirage IIIV program canceled. The surviving V 01 prototype is on display at the Musée de l’Air et de l’Espace, Paris Le Bourget.

Mirage IIIV Prototype V 01 on display

Details of the Mirage IIIV’s lift jet inlet doors

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The XFV-12A on the ramp at NAA (Rockwell)‘s plant in Columbus, Ohio

In 1972, the US Navy issued a request for proposals for a VTOL fighter capable of Mach 2 speeds to operate from its planned !!!error: Indecipherable SUB-paragraph formatting!!! . Convair submitted its !!!error: Indecipherable SUB-paragraph formatting!!! , but North American’s (later Rockwell) proposal won out, and was designated the XFV-12. To reduce costs and construction time, the XFV-12 used parts from a Douglas Skyhawk (the nose) and the McDonnell F-4 Phantom (intakes). The XFV-12 was to produce vertical lift by directing jet exhaust through ducts in the wings and canards, drawing in and accelerating surrounding air. This arrangement would preclude mounting weapons on the wings, limiting the XFV-12's weapons to a 20mm M61 gun and two or four AIM-7 Sparrows carried in semi-recessed niches under the fuselage.

The XVF-12 undertaking tethered hover testing

The prototype was rolled out of Rockwell International’s plant on 26 August 1977, and flight testing began the following year. It soon became apparent that the thrust augmentation system did not scale up as anticipated, and the XFV-12 proved to be unable to achieve vertical flight. While a more powerful engine could have been fitted, the Navy saw no future in the program, and canceled the XFV-12 in 1981. The aircraft was disassembled and placed into storage after being canceled, though in 2012 a group of students from !!!error: Indecipherable SUB-paragraph formatting!!! began restoring the cockpit section for possible use as a museum display.

kanadanmajava1 > user314 11/06/2020 at 11:15

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“ The Mirage IIIV was roughly twice the size of the Balzac, and was intended to be a fully realized Mach 2+ VTOL strike fighter. Lift was provided by eight Rolls-Royce RB162-1 engines, with forward thrust coming from a Pratt & Whitney JTF10 turbofan with afterburner, later upgraded to a TF106 augmented turbofan. ”

Hmm. 8+1 engines. I wonder if this a record for the number of engines controlled by a single pilot? Some Saab VTOL concept plane had 12+1 but it only existed on paper.

Who is the Leader - 404 / Blog No Longer Available > user314 11/06/2020 at 11:24

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Even as the Kinjapocalypse closes in, Skyfire keeps the content coming.

user314 > Who is the Leader - 404 / Blog No Longer Available 11/06/2020 at 12:12

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I will keep this up until the end! 

Who is the Leader - 404 / Blog No Longer Available > user314 11/06/2020 at 12:13

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We are a stubborn bunch, aren’t we?

facw > user314 11/06/2020 at 17:15

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Not a fighter, but Germans also had this guy:

Dornier Do 31, with eight lift jets in the wingtip pods

user314 > facw 11/06/2020 at 20:58

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Yeah, I was going to do another post with some of the transports, now I'm hesitant