Apophenia's Offerings

[apophenia]

Not all of DefEFTA's efforts towards common procurement were successful. In 1960, the new British government instructed the RAF and Royal Navy to proceed on more frugal fighter programs. The result was a 'go ahead' for supersonic developments of the diminutive Folland Gnat.

The RAF was able to slide sideways on this order, shifting the new Gnat onto its 1962 Air Staff Target 362 requirement. AST 362 was for an advanced supersonic jet trainer to replace the original Folland Gnat T1 as well as the Hawker Hunter T7. This resulted in the RAF accepting the Folland Fo.147T as its Super Gnat T.Mk.3 [1] Advanced Jet Trainer (AJT).

Quite reluctantly, the Royal Navy took a version of the supersonic Gnat - as the Folland Firefly F.Mk.1 shipboard fighter. The small size of the Firefly was ideal for below-decks stowage but other aspects were less desirable. The original Gnat's built-in gun armament was sacrificed for extra fuel and weight reduction. As a result, the Firefly could be armed with either an external gun pod on its belly mount or it could carry two Red Top AAMs ... but not both options at the same time.

(More to come on Gnat derivatives)

_________________________

[Tophe]

Among the new ones, my favorite is the supersonic Gnat/Firefly

[GTX_Admin]

 

[apophenia]

Grown-Up Gnat -- the Folland Fo.170 Mosquito Multi-Purpose Fighter Proposal

Teddy Petter penned one final fighter design as chief engineer of the Folland Aircraft Limited. Official resistance to Petter's earlier designs -- the Fo.147 fighter (twin Rolls-Royce RB.153 Stour turbofans); Fo.148 fighter/trainer (single RB 153-61); and Fo.149 advanced trainer (single RB.153-61) -- sprang from the cost and perceived complexity of their variable geometry wings. To answer those concerns, Petter designed a scaled-up Gnat without VG, the RB 153-61-powered Folland Fo.150.

Dubbed the Mosquito, the private venture Fo.150/1 was submitted to the RAF as a multi-purpose light fighter. With no outstanding requirement for such an aircraft, the RAF quickly declined. The same fate befell the Fo.150/2 Fulmar naval fighter submitted to the Royal Navy. Thus, in British service, the Folland Fo.150 proceeded no further than a mockup. Overseas, it would have more luck. [1] But time was up for Folland Aircraft. Firefly production ended in May 1967 after which Hamble became the Southampton MRO facility of new owners Hawker Siddeley ... who then dropped the Folland name.

Avro Type 774 Archon

A more ambitious project resulted in the Avro Archon. The Type 774 Archon intermediate-range interceptor sprang out of a serious of studies conducted by Avro in the late 1950s. It was concluded that mixed power was not a winning formula and that the base Avro 720 series [2] airframe was too small for the twin-engined interceptor desired by the Air Staff.

As Avro Type 720 development ended, a team of former Avro Canada employees under Jim Floyd arrived back in the UK accompanied by reams of data on the cancelled Canadian CF-105 Arrow. From this came three distinct Avro fighter proposals. The first was a direct British Avro Arrow derivative powered by two Rolls-Royce RB.106 Tamar turbojets. Despite earlier Air Staff interest in the Arrow, this proposal was not proceeded with due to cost.

The second was a 50% scale single-seater which was regarded as a replacement concept for the Type 726 light fighter. This second type would be powered by two 21-inch diameter RB.115 Teme turbojets; two reheated Bristol-Siddeley Orpheus turbojets; or a single, larger-diameter Rolls-Royce RB.153 Stour turbofan. [3]

The third Avro fighter concept was also a single-seater. This concept was a two-thirds scaled Arrow airframe with a range of powerplant options. The most radical modification of the original Arrow layout was powered by a single RB.168 Spey turbofan (or similarly-sized alternative powerplant). More directly derived from the Arrow was a twin-engined study with two Bristol-Siddeley BE.30-3 Zeus two-spool turbojets. It was this last study than proceeded as the Avro Type 774.

With Arrow technical data to hand, work on the Type 774 proceeded fairly quickly. Being scaled-down compared with the Arrow resulted in some design challenges. The wing was no longer thick enough to accommodate the main undercarriage. Frost adopted a solution proposed for an advanced Arrow derivative -- the undercarriage units would retract into permanently-fitted underwing fuel pods.

The belly weapons bay was also now comparatively shallow. This became an interchangeable bay which could be fitted with: multiple air-to-air rocket launcher rails; a ferry tank; or a long-range combined with an underbelly pylon (in an inverted 'T' form on intial deliveries, later an inverted 'Y') armed with two DH Firestreak or HSA Red Top guided missiles. The latter arrangement became the standard fit for the RAF's Avro Archon F.Mk.1 interceptors. These aircraft also had outer wing pylons which could carry BAC-Saab Seeker lightweight infra-red guided AAM. [4]

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[1] HSA sold the entire Fo.150 project to Hindustan Aeronautics. Petter relocated to Bangalore to oversee production of his 'Fo.150/3' as the HAL HF-30 Machchhar. The 6,580 lbf RB 153-61 engine was also built in India as the HAL HJE-6500 Shakti.

[2] The rocket powered Avro Type 720 was followed by two mixed-power concepts -- the Avro 726 light fighter for the RAF and Avro 728 for the RN. The Bristol Orpheus-powered Type 727 was intended as a NATO ground attack fighter.

[3] The Rolls-Royce RB.153 Stour was a reduced-scale development of the RB.168 Spey turbofan.

[4] The Seeker was the British production version of the Saab Rb 33 Sökare IR missile.
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[The Big Gimper]

All these wonderful profiles have given me another 20+ years of work. I just abid adieu to my family as I walk into the modelling dungeon.

[Old Wombat]

Like the Archon, looks really good!

[Tophe]

Thanks for the new profiles and explanations
Is this pure imagination or History (of true projects)? Congratulations anyway.

[ChernayaAkula]

Like the Archon, looks really good!

+ 1! Gorgeous! 

[GTX_Admin]

 

[apophenia]

Thanks folks. When I find time, I will write up an alternative EFTA scenario.

Thanks for the new profiles and explanations
Is this pure imagination or History (of true projects)? Congratulations anyway.

Tophe: Nary a real-world project to be seen in that post. It is true that Jim Floyd returned to the UK with a gang of Avro Canada engineers. But they worked on SSTs in HSA's Advanced Projects Group (leading to Concorde) not on fighter aircraft.

AFAIK, the unbuilt swing-wing Fo.148 was WEW Petter's last project for Folland. Petter lasted less that a year after Folland was absorbed by HSA. After that, he left aviation for good.

[apophenia]

Where cooperative DefEFTA projects could not be agreed upon, EFTA member states were free to 'go it alone'. Most such efforts were modest, resulting in light aircraft such as Portugal's updated OGMA Chipmunk II trainers and Sweden's Saab Supporter AOP/COIN aircraft. Britain, however, had a strong tradition of advanced fighter design which its industry was determined to preserve.

The HSA Hurricane and BAC Tempest [1] were two products of that determination. The Hurricane was a supersonic VTOL interceptor while the single-seat Tempest was a variable-geometry strike fighter. The two aircraft types would have very different fates.

The Hurricane evolved out of an earlier plenum-burning project, Hawker Siddeley's P.1154. The P.1154 suffered from shifting RN priorities for new carrier-based fighters. As a result, this design became too large and expensive to be a good match for RAF requirements. Rejigged as the Hurricane, the VTOL fighter 'fell between stools', suiting neither British service.

Although no other EFTA member expressed great interest in the Hurricane, prototypes were demonstrated in both Sweden and Switzerland. While at the Swiss test facility at Emmen [2] the third prototype Hurricane suffered an inflight fire in it starboard engine. Both Swiss test pilot and onboard HSA engineer ejected safely but the Hurricane P.03 was a write-off. The remaining prototypes flew from Boscombe Down with the A&AEE for some years but no production order for the Hurricane was ever issues.

The BAC Tempest was an attempt to take advantage of a British lead in variable-geometry wing technology. The design began as the P.45 advanced trainer/strike fighter concept. After review, it was concluded that the combined RAF requirement was unrealistic. From that point, the P.45 design was refined as a dedicated strike aircraft which emerged at the BAC Tempest. Despite being a 'go it alone' project, the Tempest would eventually serve in the Danish and Norwegian air forces as well as the RAF.

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[1] The British government encouraged the use of 'heritage' design office names for aircraft, rather than those of conglomorate corporations. However, here, both Hawker Siddeley and the British Aircraft Corporation saw these projects as genuine group efforts rather than products of a particular design office.

[2]  The Emmen-based test unit is the Abteilung für Flugversuche,part of the Flugwaffe's Gruppe für Rüstungsdienste.

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[apophenia]

EFTA Common Airlifter - the Short-Saab Sheffield/Svalbard Tactical Transport

In Feb 1959, Shorts' design office began work on a large transport aircraft based upon Bristol Britannia wings. Submitted for review as the Short SC.5/10, at the behest on the new coalition government, the Air Staff recommended that the concept be scaled-down and based on more modern components - those of the Vickers 803 Vanguard airliner. [1] Following those recommendations, a revised airlifter concept - the Short SC.5/22 [2] - was resubmitted to the Air Staff.

The SC.5/22 was accepted for RAF service as the Short Sheffield C.1 (with the first two production airframes doubling as development prototypes). The Sheffield first entered service with No.53 Sqn at Abingdon in November 1965. [3] Eventually, the Sheffield would replace all Blackburn Beverley, Handley-Page Hastings, and Bristol Britannias in RAF service.

(Top) A Short Sheffield C.1 'Heracles' (AR367) of No.53 Squadron at RAF Brize Norton in late 1967. Like all but the first two Sheffield C.1s, this aircraft is finished in tactical camouflage. 'Lo-viz' roundels and fin flashes would replace the semi-lustre national markings by mid-1969.

Note: Early-style horizontal inflight refuelling probe and absence of any tailcone ECM antennae.

Component production of the Sheffield was shared between Shorts (fuselage), Vickers-Armstrong (wings and nacelles), Saab (tailplane), and Dowty (undercarriage and propellers). Final assembly was by Shorts at Belfast and Saab at L . In Scandinavian service, the aircraft was known as Svalbard - a name adopted by its first Nordic customer, the Royal Norwegian Air Force. [4] Sweden followed (with their Tp 86 Svalbard) as did, eventually, Denmark.

(Bottom) One of three Danish Svalbards fitted out for Faroe Islands/Greenland missions. Flyvevåbnet Pennant B-679 is in well-worn 'overseas' colours ('Atlanterhavet' blue over pale grey with hi-viz 'Grønland' panels added). The crest of 721 Eskadrille appears on the forward fuselage on this Aalborg-based Svalbard.

Note: Large comms antenna on the tailfin (soon to be replaced) and the newly-added Terma A/S electro-optical turret beneath the nose.

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[1] This was inspired partly by economic concerns, partly by the contemporary Franco-German Transall C160.

[2] The earliest revised SC.5 concepts used the Vanguard's large R-R Tyne turboprops (the SC.5/11 to SC.5/14 having 4 x Tynes, SC.5/15 to SC.5/18 having 2 x Tynes like the Transall). The later revisions, including the SC.5/22, switched to 4 x R-R Darts - a more economical engine.

[3] No.53 Sqn had flown Blackburn Beverleys at RAF Abingdon until disbanded in June 1963. The squadron was reformed on Sheffields in November 1965 before moving to Brize Norton in 1967.

[4] The Kongelige Norske Flyvåpen bought six Saab Svalbards, replacing eight C-119G Boxcars in service with 335 skvadron since 1956. One Norwegian Svalbard (BW-G, 'Brage') was written off in an accident, appropriately enough, on Svalbard. The replacement Svalbard was named 'Froya' but reused the BW-G skvadron kode.

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[Logan Hartke]

That Hurricane ends up looking a lot like a Mitsubishi T-1 when you combine the Phantom and Harrier like that.

Cheers,

Logan

[apophenia]

Beagle B226TP / Basset CC.Mk.4

The B226TP of May 1965 was a straightforward turboprop development of the Beagle B.206 Srs 3. [1] As a civilian executive transport, Beagle marketed this aircraft as the Beagle B226 Basset. When Beagle became part of the newly-formed DH Group, new marketing policies confused matters somewhat. Any military-related work by Beagle was now to be marketed under the Blackburn Aircraft name. One result was that although the aircraft had entered RAF service as the Basset CC.Mk.4, [2] such military models were marketed internationally as the Blackburn B226 Beagle!

Ultimately, the B226TP had more success in the commercial realm but military models included: light transports, multi-engined trainers, maritime surveillance, and overland surveillance-reconnaissance types (the latter two models sporting grotesquely-large belly radomes for search radar antennae).

(Bottom) A Basset CC.Mk.4 'air taxi' newly delivered to the RAF

Beagle B.236/Blackburn B236 Boarhound

The B236 Boarhound saw its origins in the ambitious Beagle B.212 (2) project of 1964 for a counter-insurgency derivative of the proposed B.212 (1) - a T-tailled, turboprop feederliner. Neither project saw the light of day as the realities of Beagle Aircraft's financial constraints kicked in.  Rather than abandon the concept completely, Beagle Chief Designer Tom Carroll, DFC, adapted the 2-seat [3] COIN aircraft concept to the B.206R (RAF Basset CC.Mk.1) airframe.

The B236 was a hybrid of Basset and B.206S (B.206 Srs 2) components with a completely new forward fuselage and the turboprop nacelles of the B226. The prototype Boarhound emerged with an RAF-supplied cockpit canopy (from a Meteor NF.11 fighter) and Canadian-built PT6A-3 engines. For the 1965 Farnborough Air Show, those engines were replaced with Napier-assembled NTP-6A Rapier turboprops and the B236 prototype was fitted with four wing pylons.

(Top) The B236 Boarhound prototype as it appeared at Farnborough 1965. (The Beagle logo on the nose was removed before the aircraft was returned to Boscombe Down for further testing.)

The B236 prototype was the only Boarhound completed by Beagle Aircraft. Everything changed with the reorganization under the new DH Group. It was decided that Beagle should concentrate on civil types while all of Beagle's military work would be transferred to DH Group affiliate, Blackburn Aircraft. Shoreham would continue to supply rear fuselages and other components while Boulton and Paul would build wings and tailplanes at Wolverhampton but final assembly would take place at Brough.

The prototype was also the only Boarhound accepted by the RAF. A revised MoD policy shifted all propeller-driven COIN from the RAF to the British Army or Royal Marines. All series Blackburn Boarhounds were finished in Army green upper surfaces with 'lo-viz' markings. Series aircraft also featured one-piece clear-blown canopies, wingtip tanks, and a stronger B226 undercarriage.

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[1] Note that the 'period' in Beagle designations was eliminated in the reorganization of 1965.

[2] The Basset CC.Mk.1s were the RAF's original 22 Beagle aircraft. The Basset CC.Mk.2 was a single Beagle B.206S loaned to the RAF for comparison purposes. The Basset CC.Mk.3 designation was reserved for a planned purchase of the Beagle B.206 Srs 3 (that contract then being revised to cover an equal number of Rapier-powered Basset CC.Mk.4s instead).

[3] The cockpit arrangement was revised for the production-model Blackburn B236. The Boarhound prototype's ugly Meteor 'hood' was replaced by a shorter, one-piece canopy. In the process, a central 'jumpseat' between the pilot and weapon operator's positions was eliminated.

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[Tophe]

Sorry, I did not know the source well enough to appreciate your transformation... But thanks to have mentioned the source:

development of the Beagle B.206 Srs 3.

Then I asked Google to show me this source (like https://c1.staticflickr.com/9/8185/8398242704_8b4c5f05c2_b.jpg ) and now I like your transformation, thanks!

[Old Wombat]

The Boarhound would look pretty good with a proper bubble canopy.

[apophenia]

Thanks folks. Tophe ... that was the exact photo that I took my rear fuselage decking from

Now, a quick break from the EFTA thread. Ages and ages ago, von hitchofen2 asked for an Israeli Bloch MB 155 and, after a jog to memory, here it is:
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Israeli Blochs - Société Anonyme des Avions Marcel Bloch Fighters in Kheil Ha'Avir Service

In late 1947, the French firm SAAMB (la Société Anonyme des Avions Marcel Bloch) delivered a range of reconditioned fighters to Israel. All were refurbished with German avionics from Luftwaffe dumps and fitted with tailwheels (from Ar 196Bs) These aircraft were primarily Bloch MB 155 fighters - known as the Pattish (Hammer) in Israeli service - with a handful of SAAMB MB 155T dual-control trainers.

The MB 155Ts - known as the Gur-aryeh (Lion Cub) - were 2-seat trainers based on rebuilt ex-Vichy MB 151/MB 152 airframes fitted with MB 155 powerplants and cowlings. [2] The Gur-aryeh was not popular in Israeli service - it was short on range and had been delivered without radio transmitters - but the MB 155T made an ideal transitional trainer on to MB 155 fighters.

(Top) An MB 155T Gur-aryeh freshly transferred to 107 OTU at Ramat David, summer 1949. This Gur-aryeh still wears tail-stripes and fuselage band from its time with 101 Tayeset but the individual aircraft serial has been scrubbed. Note that the wings roundels have been repainted but the non-standard, factory-applied fuselage roundel has yet to be resprayed.

The MB 155 Pattish was more popular with Kheil Ha'Avir pilots. Its short-barrelled British Hispano Mk.V cannons [2] had greater range than the Avia S.199's Mauser guns of the same calibre. As a result, the Pattish were employed mainly for ground strafing, freeing up the rarer Spitfires for the top cover role.

(Bottom) MB 155 Pattish of the 101 Tayeset at Ekron in June 1948. '104.ד' is in near-pristine condition (with full squadron markings yet to be applied). The Pattish were unique among 101 Tayeset fighters in not having red spinners. The MB 155's off-centre engine mounting made a 'Spinnerspiral' spinner particularly effective at confusing the aim of enemy ground forces.

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[1] The SAAMB MB 155T was based loosely on an Italian dual-control conversion of captured MB 151s.

[2] The Pattish was armed with twin 20 mm cannons and two 7.92 mm MAC Mle 1936/39 machine-guns. The MACs were guns bored out for German use during the Occupation. Most MB 155Ts were armed with two wing-mounted machine guns although some were delivered without armament.

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[apophenia]

... which inspired this:
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Dual-Control Blochs

The MB 159 Ins 2 was a conversion trainer for the Bloch MB 151-155 series fighters. Initial MB 159 Ins 2 were conversions from early-production MB 151 fighters. These aircraft had an instructor's cockpit inserted in the rear fuselage displacing the main fuel tank. [1] Some aircraft were fitted with sliding hoods for the instructor, others had open rear cockpits.

(Top) A captured Bloch MB 159 Ins 2 in service with the Regia Aeronautica as an MB 159 dc (Doppio Commando). [2] This was originally an open-cockpit Ins 2. The rear cockpit side 'flaps' (and revised antenna arrangement) were part of a minor refurbishment program by OMI Reggiane to suit the Bloch trainers to Italian service.

Later-production MB 159 Ins 2 models (known as the MB 159B T2 by Vichy authorities) [3] omitted the fighter's raised rear fuselage decking. The instructor's cockpit was fitted with a sliding hood behind which was a new, glazed 'turtle-deck' fairing.

(Bottom) An MB 159 Ins 2 newly refurbished for Vichy use as an MB 159 T2. Note that this aircraft is fitted with the back-up ring-and-bead sight but that its reflector sight has been removed.

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[1] MB 159 Ins 2 fuel tankage was divided between multiple tanks - in the former gun bays, centre fuselage, and a small tank integral with the instructor's seat. Nevertheless, much-shortened range was an operational limitation for the MB 159 Ins 2.

[2] Also sometimes referred to simply as the 'Bloch Biposto', Italian sources most often refer to the 'MB 159 dc' (or 'MB 159 DC').

[3] The Armée de l'Air 'Ins' was for Instruction (for conversion trainer).  It is not clear why Vichy chose the 'T' designator. French intermediate trainers were normally given an 'ET' for Entrainement designation. Vichy officials either shortened that 'ET' designator or, more likely, applied a 'T' for Travail (General Purpose) designation to mislead their German overseers.

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[Tophe]

I think I have never seen a tandem-seat Bloch of the 150 series, are you the inventor of it?

[GTX_Admin]

 

[apophenia]

I think I have never seen a tandem-seat Bloch of the 150 series, are you the inventor of it?

Sssh, cela devrait rester confidentiel ... même Marcel Bloch n'a jamais entendu parler des MB 150s à deux places!

Hispano-Powered Bloch Fighters - the SO 154/MB 154B

The Vichy regime faced an on-going shortage of Gnome-Rhône engines for its Bloch fighters. The Bloch MB 154 was a still-born Wright Cyclone-powered MB 152 proposal. After the Armistice, stocks of HS 12Y powerplants were available. It was decided to complete MB 155 components as Hispano-powered MB 154Bs (in the Vichy designation style).

The redesign resulted in a radically different-looking fighter. Besides powerplant, the MB 154B differed from the MB 155 in having its cockpit moved even further aft to accommodate a Hispano-Suiza 20 mm moteur-canon. The engine installation and much of the cowling were taken from the rival Dewoitine D.520 fighter (as was the tailwheel - specified by the Germans to replace the typical Bloch fighter tailskid).

By agreement, the protoype was delivered to German authorities as the SNCASO SO 154 V1. [1] The Germans were interested in this aircraft as a potential advanced fighter-trainer. The prototype was fitted with an early-model HS 12Ycrs engine and a refurbished HS-404 cannon. [2] Performance suffered according ... which was possibly the French technicians' purpose in choosing somewhat antiquated equipment for the SO 154 prototype.

(Top) The prototype SO 154 V1 as delivered to German Occupation Authorities after 'Germanization' at Bordeaux-Aéronautique. Note that, at this stage, the prototype retains its French R/T gear but a German gunsight has been fitted. The unpainted cowling has yet to receive a coat of RLM 04 recognition yellow but Rechlin test codes have been applied prior to the flight to Germany.

The indifferent performance of the SO 154 V1 ensured that the Germans quickly lost interest in the project and released the SO 154 for exclusive Vichy use. The prototype remained at Rechlin but the ultimate fate of SO 154 V1 is unrecorded.

The Bloch MB 154B (as the SO 154 was known to Vichy) was to have been a 'heavy fighter' armed with three 20 mm Hispano-Suiza HS-404 cannons - one as a moteur-canon and two wing-mounted guns. That plan was thwarted by a shortage of 20 mm guns. Instead, first series MB 154Bs were delivered with their wing cannon positions blanked off and two MAC machine guns mounted outboard. Second series fighters had a moteur-canon with four wing-mounted machine guns. All MB 154Bs were powered by the available HS 12Y-31 engines but the planned MB 154D [3] with a more powerful HS 12Y-45 never came to fruition.

(Bottom) A Vichy Bloch MB 154B of Groupe de Chasse II/5 in Morocco. The 'Hispano Bloch' fighters joined Hawk 75As of GC II/5 at Casablanca before redeploying as a bomber escort flight temporarily based  at Médiouna airfield. This MB 154B never received an individual aircraft number - it was lost returning from a 24 Sept 1940 raid on Gibraltar (probably due to damage from anti-aircraft fire).

After December 1940, GC II/5 was able to standardize on Curtiss H75As. All remaining MB 154Bs in North Africa were reassigned to GC II/3 at Oran where they served alongside Dewoitine D.520s. By 1943, the surviving MB 154Bs [4] had been transferred to Marrakech - where most were destroyed on the ground by strafing US Navy F4F-4 Wildcats during Operation Torch.

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[1] To the Nazis, Marcel Bloch was an 'undesirable' and they would not apply his Ashkenazic surname to aircraft ordered for the Luftwaffe. The German authorities encouraged the Vichy regime to also adopt SNCASO designations but 'MB' designations remained in common use (with 'Sud-Ouest' regarded as interchangeable with 'Bloch').

[2] In all probability, the SO 154 V1's engine and armament combination originated with a retired or wrecked Dewoitine D.510 fighter.

[3] No 'MB 154C' sub-style designation was ever applied, probably to avoid confusion with the Armee de l'Air de Vichy's C1 (Chasse, Monoplace) suffix designator.

[4] Other than test airframes, no Bloch MB 154Bs served in Metropolitan France.

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[Tophe]

Beatiful in-line Bloch fighters! (even if this is the bad side, sorry...)

[Old Wombat]

The 154's look good!

[apophenia]

Thanks folks. Tophe: Sorry, more "bad side" to come after this one 

Bloch MB 151-At - the Accidental Assault Variant

Several 'MB' fighter variants were forced upon Bloch by circumstances out of the firm's control. By early 1940, airframe production was outstripping the supply of vital components. Bloch could do nothing about a shortage of Gnome-Rhône engines but MAC machine guns could be substituted for rare HS-404 cannons. The shortage of Ratier propellers, Bloch decided to tackle head-on.

Marcel Bloch had first made his reputation with the 1915 Éclair propeller. [1] In light of the difficulties experienced obtaining sufficient Ratier airscrews, it was decided to restart the Société des Hélices Éclair. Established at Châteauroux in central France, Éclair would first produce propellers for the MB 151/152 fighters. These differed from the variable-pitch Ratier propellers primarily in having wooden 'paddle' blades.

The heavier Éclair propellers had a slightly deleterious effect on performance - especially climb rate. This prompted the ad hoc development of a new sub-type. Available Ratier propellers went to unfinished MB 152s while idle MB 151s were completed with Éclair units to create a new ground-attack variant - the MB 151-At (for Assaut). These airframes were equipped with light-bomb racks under their wings and provided with a greater degree of armour protection (including externally-fitted armour-glass windscreens).

(Top) A Bloch MB 151-At ground attack aircraft of the newly-formed GAt I/4 at Sedan. (Note Société des Hélices Éclair logo on rudder.)

The Nose Knows - Alternative Radial Engines for Bloch Fighters

The on-going supply shortage of Gnome-Rhône 14N radials led Bloch to seek out alternatives. The most extreme outcome was the HS 12Y-powered MB 154B. But, following an Armée de l'Air directive, SNCASO design staff also examined potential foreign engines. Four candidate engines were examined - the British Bristol Taurus and Hercules and US Pratt & Whitney Twin Wasp 14-cylinder radials, and the Wright Cyclone 9-cylinder radial. The  14-cylinder variants were designated MB 153 while the Cyclone-powered variant was to be the MB 154.

Neither of the Bristol options were pursued and, as we've already seen, the Cyclone-powered MB 154 was later abandoned. Thought more promising was the Twin Wasp-powered MB 153 variant since that engine was already in Armée de l'Air service (with the Curtiss Hawk 75A and Martin 167F bomber). An MB 152 [1] was converted to take the Pratt & Whitney radial (in a cowling similar to that of the MB 176 reconnaissance bomber). The production model MB 153 C1 was to be based on the MB 155 airframe. None of the production MB 153s was delivered to the Armée de l'Air. MB 153 C1 No.002 was delivered in a semi-completed form to the German Occupation Authorities but was never flown.


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[1] In the original Société des Hélices Éclair, Bloch had partnered with Henry Potez.


[1] Sources vary as to whether No.434 was originally an MB 152 or an MB 151 model. SAAMB MB 155T was based loosely on an Italian dual-control conversion of captured MB 151s.

[2] The Pattish was armed with twin 20 mm cannons and two 7.92 mm MAC Mle 1936/39 machine-guns. The MACs were guns bored out for German use during the Occupation. Most MB 155Ts were armed with two wing-mounted machine guns although some were delivered without armament.

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[von hitchofen2]

snip!

 

Excellent work!