Back in Les Prototypes galerie, we begin where we left off, with the promise of high speed and the Mirage III. Prior to Marcel Dassault's delta winged jet's enormous success, the quest for a Mach 2 supersonic fighter was being pursued by a few different manufacturers in France, to a requirement issued in 1953. We looked at Leduc's ramjets and the the folly they turned out to be, but they weren't the only ramjets being tested at the time. As we know, ramjets require another means to start from a stand still and Leduc, in his 022 interceptor buried a conventional jet engine within the core of the athodyd. The engineers at Société Française d'Etude et de Construction de Matériel Aéronautiques Spéciaux or SFECMAS, while envisioning a high speed interceptor came to the same conclusion, but were a little more cautious in their approach; unlike Leduc however, they were going to build a test bed prototype before launching into a full blown interceptor. The result was the 1500 Guépard (Cheetah). At the time, SFECMAS was merged with SNCAN to form Nord Aviation and the Cheetah became the mythical Griffon. As per Leduc's flying barrel, the Griffon was similarly shaped, but with a low set intake with a protruding nose section mounted above it. Buried within the fuselage was a combined turbojet-ramjet arrangement, which would enable high speed operations as well as cater to conventional requirements. First flying on 20 September 1955 piloted by the Great Andre Turcat, the first Griffon was powered by a single SNECMA Atar 101 turbojet (which, for those Luftwaffe aficionados among you was based on the BMW 103-003 that powered the He 162 and Ar 234) but devoid of the functioning athodyd, thus proving the aerodynamics of the design.
The remarkable visage of the Griffon is revealed in this view from an elevated position. note that compared to the monstrosity that was the Leduc 022 to the right, the Griffon is relatively small and in size is comparable to the Mirage III behind it.
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Wiki goes into detail about this particular example;
"On 23 January 1957, the Griffon II performed its first flight. During April 1957, all flying of the Griffon I was ceased in favour of focusing on the ramjet-equipped Griffon II. During a high speed test flight conducted in 1958, the Griffon II successfully attained a peak speed of Mach 2.19 (2,330 km/h or 1,450 mph) while being piloted by Turcat. This milestone was viewed as having proved the basic design of the aircraft to be sound. However, the flight test programme had revealed several technical difficulties were present in the aircraft, including concerns regarding kinetically-generated heat; the thermal issues were exacerbated by a lack of temperature-resistant materials, such as Inconel or titanium, for portions of the airframe that encountered the highest temperatures. The ramjet was determined to have functioned well when the aircraft was flown at high speeds, but exhibited instability while flying at medium speeds."
Following the results of the Griffon's test regime, the 'Super Griffon' promised to rectify the issues encountered, but, as we know, the more conventional and less technically ambitious Mirage III pipped the ramjet concept to the post. The Griffon II from the rear; note the enormous exhaust orifice and landing parachute in its fairing on the fin. We'll be looking at a third entry in the supersonic interceptor competition in our next installment.
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We now look at another indulgent aeronautical project that numerous manufacturers researched during the 50s and beyond - the vertical take-off and landing (VTOL) aircraft. Staying with our engine manufacturer friends at Atar, which incidentally stands for Atelier technique aéronautique de Rickenbach, which was a group of German scientists that were pooled together in 1946 in the former Dornier factory at Rickenbach in Baden-Württemberg, but working for the French. These guys were led by notable designer Hermann Oestrich, who, along with fellow BMW engineers was responsible for the BMW 003 and had designed a more advanced variant, which became the Atar 101, under French agreement and built by SNECMA. Essentially an Atar 101 engine mounted vertically in a tubular casing and erected on a four-poster undercarriage framework, the Atar Volant was a vertical lift test bed family, of which three were built. The first was piloted by remote, but the second, seen here had an ejection seat, instrumentation and controls for the pilot (balls-of-steel were apparently a requirement). Producing 6,200lbs thrust, the manned Atar Volant C.400 P.2 first flew attached to a gantry in April 1957, before its first untethered flight on 14 May flown by August Morel, who was to be injured testing a more advanced example of the technology. It made a total 0f 123 tethered and free flights, including a public display at the Paris Airshow.
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Following the C.400s was the SNECMA C.450 Coléoptère, which was intended as a test bed for a vertical lift concept incorporating an annular circular wing invented by Austrian Helmut von Zborovski, which, he theorised could provide any so equipped aircraft with a ramjet housing that could accelerate any aircraft to supersonic speeds (again with the ramjet). (Coléoptère, incidentally means "beetle" in French, descended from Greek for "sheathed wing"). This rather long shot concept was trialled and revealed from our usual source;
"During early 1958, the completed first prototype arrived at Melun Villaroche Aerodrome ahead of testing. The eye-catching design of the Coléoptère rapidly made waves in the public conscious, even intentionally; author Jeremy Davis observed that the aircraft had even influenced intentional efforts, having allegedly motived the United States Navy to contract American helicopter manufacturer Kaman Aircraft to design its own annular-wing vehicle, nicknamed the Flying Barrel. In December 1958, the Coléoptère first left the ground under its own power, albeit while attached to a gantry; Morel was at the aircraft's controls. Several challenging flight characteristics were observed, such as the tendency for the aircraft to slowly spin on its axis while in a vertical hover; Morel also noted that the vertical speed indicator was unrealistic and that the controls were incapable of steering the aircraft with precision while performing the critical landing phase. Dead-stick landings were deemed to be an impossibility."
"Morel conducted a total of eight successful flights, attaining a recorded maximum altitude of 800 m (2,625 ft). One of these flights involved a display of the aircraft's hover performance before an assembled public audience. The ninth flight, on 25 July 1959, was planned to make limited moves towards entering horizontal flight; however, hindered by insufficient instrumentation and a lack of visual benchmarks, the aircraft became too inclined and too slow to maintain its altitude. Morel was unable to regain control amid a series of wild oscillations, opting to activate the ejection seat to escape the descending aircraft at only 150 m (492 ft). He survived but was badly injured, while the aircraft itself was destroyed. While plans for a second prototype had been mooted at one stage, such ambitions ultimately never received the funding to proceed."
At least the wind tunnel model looks nice.
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Our next ascent into VTOL eccentricity is the Sud Aviation/Aérospatiale SA-610 Ludion (Cadet). Wiki again;
"It consisted of little more than a chair, behind which were mounted two downward-pointing augmented rocket engines with control provided by thrust vectoring. The Ludion was intended to carry its pilot and 30 kg (66 lb) of equipment up to 700 m (2,300 ft) at an altitude of up to 200 m (600 ft). The unusual powerplant consisted of a monofuel de-composition chamber fed with pressurised isopropyl nitrate (AVPIN), ignited by a catalyst. The high pressure gasses produced in the de-composition chamber were fed to two augmentor tubes, built by Bertin Technologies, either side of the pilots seat, angled slightly outwards. As the gasses entered the augmentor tubes through rocket nozzles, thrust was augmented by inducing airflow through the ducts which acted as aero-thermo-dynamic ducts, due to the heat and kinetic energy added to the flow through the ducts, and the carefully shaped exhaust nozzles."
Apparently the British provided information on the use of Avpin as a hypergolic fuel, after research by the Rocket Propulsion Establishment at Westcott with German T-stoff and C-stoff propellants from the Walther Werke in Hamburg. 'Nuff said...
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Remaining with the en-vogue obsession of vertical take-off of the era, the next airframe of note is from Dassault's hand, the Mirage III V - a practical attempt at a VTOL combat aircraft built to a military specification. In August 1961, NATO released an updated revision of its VTOL strike fighter requirement, NATO Basic Military Requirement 3 (NBMR-3). Specifications called for a supersonic V/STOL strike fighter with a combat radius of 460 kilometres (250 nmi). Cruise speed was to be Mach 0.92, with a dash speed of Mach 1.5. The aircraft, with a 910-kilogram (2,000 lb) payload, had to be able to clear a 15-metre (50 ft) obstacle following a 150-metre (500 ft) takeoff roll. Victory in this competition was viewed being of a high importance at the time as it was seem as being potentially "the first real NATO combat aircraft" (thanks wiki). The other significant entry into NBMR-3 was the Hawker Siddeley P.1154, which was to be a supersonic VTOL jet named 'Harrier' incorporating a novel single powerplant with four vectored thrust nozzles. The supersonic variant of the basic Bristol Siddeley Pegasus engine was to incorporate what was called plenum chamber burning (PCB) to achieve supersonic thrust, which was a major contributor behind the programme's downfall (regulating temperature and thrust output in two different thrust chambers simultaneously became something for the 'too hard basket', apparently). Nonetheless, without making this a post about the P.1154, which could easily fill a book, the Dassault team opted for separate jet-lift engines, which again the British had tested with the Short SC.1, eight Roll-Royce RB.162 vertically mounted jet-lift engines, with deflectors that could vector the thrust in flight.
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A truly international effort, Dassault received much assistance for the Mirage III V from Britain - its predecessor the Balzac was powered by a Bristol Orpheus engine with R-R RB.108 jet lift engines - and its primary engine came from the United States. This was the Pratt & Whitney JT10A low bypass turbofan, which was to power the cancelled Douglas F6D Missileer, but went on as the TF30 to power the General Dynamics F-111. Although propelling the Mirage III V to supersonic speeds, the second prototype achieved Mach 2 in September 1966, the jet never achieved vertical take off and supersonic speed in the same flight. Following the loss of the second prototype and its pilot in November 1966, Dassault pulled the plug on the programme, and, by this stage the P.1154 had been declared the winning submission to the NATO tender, which further dissuaded any official interest in the jet. Technologically simpler than the P.1154, the Mirage III V looked to be a very real possibility for a practical supersonic VTOL combat aircraft, but the impracticalities of carrying around extra engines and the extra fuel to feed them, thus consuming useable load carrying capability meant the death knell of many VTOL projects of the time. Only the Soviet Yak-38 entered service with separate lift engines, supplanted by a vectored thrust main engine, but the P.1154's direct descendent, via the P.1127 and Kestrel, the Harrier was a far greater success, as we know.
Missing its American engine, the Mirage III V prototype is one of a number of VTOL projects from the period with little practical result that litter aviation museums around the world.
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Finally for today, we stay with Dassault and take a look at another global aviation trend that appeared around about the same time as the VTOL revolution became consigned to the scrap heap (with the exception of the aforementioned Harrier and Yak-38, of course, which, strictly speaking were more accurately STOVL, than VTOL); variable geometry wings. It is interesting to note that a response to a French government requirement for a joint navy and air force supersonic variable geometry aircraft issued in 1964, the Mirage G aircraft were based on Dassault's Mirage F2, which was powered by the Mirage III V's US engine, the TF30 manufactured under licence by SNECMA. This particular aircraft was designed as a sophisticated low altitude strike aircraft, but was rejected in favour of Dassault's low tech version, the Mirage F1. Fitting variable sweep wings to the F2's fuselage, the wings were swept at 22 degrees when fully forward and 70 degrees when fully aft and featured full-span double-slotted trailing edge flaps and two-position leading edge flaps. In this view of the Mirage G8 01 prototype, its leading edge and trailing edge surfaces are deployed and the wing is in forward sweep.
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Initially, the concepts for the Mirage G family came out of France's dissatisfaction for the joint Anglo-French Variable Geometry (AFVG) programme, which, having France withdraw led Britain to look for new suitors, rather like a dating game, which they did in the form of Germany and Italy, which, combined created Panavia and the excellent Tornado multi-role combat aircraft. I guess the success of Tornado and the lack of a French equivalent could be considered payback for Dassault's comments about the Mirage success eluding the British! Designed as prototypes for a dual service aircraft, the G8s were intended on carrying a full suite of radar and nav-attack systems, but it all came to nought and a French VG aircraft never entered service, despite the Mirage G's obvious potential. This wasn't the end of it though - it was to have influence outside France, somewhat implausibly in the United States, as wiki attests to;
"In the late 1960s, the US manufacturer Ling-Temco-Vought (LTV) was seeking technical data on variable-geometry wings, within the framework of a bid for the US Navy's VFX carrier fighter contract. As a result of the publicity gained by the Mirage G, LTV sought the assistance of Dassault, as well as General Dynamics, which had secured a contract with the USAF for a variable geometry fighter-bomber/attack aircraft, the F-111A. Two agreements were signed by Dassault and LTV in 1968: one for general cooperation and the other specifically in regard to variable-geometry wings. This resulted in two LTV designs, the Vought V-505 and V-507, as well as construction of a full-scale, non-flying mockup of the second design. There were two competing bids, both with variable geometry: the McDonnell F-4(FVS), which was a variant of the Phantom II, and the Grumman 303. The latter was successful and was developed into the F-14. However, during its development, Grumman approached LTV for details of the V-507, including some of the same technical solutions devised for the Mirage G."
In this view the left hand wing is at full rearward sweep. That's a Bristol Hercules incongruously parked under its wingtip.
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Coming up, more Prototypes.