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  • Writer's pictureCaptain Crisp

Solent Rocket Fighters

After brief combat action between the Allies and the Messerschmitt 163 Komet rocket fighter during the latter part of the Second World War, where this diminutive aircraft had proved to be the fastest combat aircraft of any nation during the war, captured examples of the Komet were understandably of great interest to the allies, especially as a standard production Me 163B fitted with an experimental twin chamber rocket motor was flown by test pilot Heini Dittmar on 6 July 1944 at the [then] phenominal speed of 702 mph [1130 kmh], an unofficial world absolute speed record.

The lethal Me163 Komet

To put that into perspective, the fastest fighters the Allies had in July 1944 were the Griffon Spitfires, Sabre Typhoons and Merlin Mustangs – all of which could just about reach 450 mph [720 kmh]. The two Meteor jet aircraft that set official world speed records in 1946 could still only reach 606 mph [975 kmh] and [616 mph [991 kmh]. The aircraft’s airframe was not the major interest, although it was a tiny futuristic tail-less swept wing aircraft, the rocket engine power plant and the potential of rocket thrust for fighters most certainly was. The Komet was powered by a 3700lb thrust rocket engine powered with a mixture of hydrogen peroxide and hydrazine hydrate methanol.

Britain's rocket technology evolved from captured German research

This lethal chemical mix gave a standard maximum speed of 597mph and [what interested the allies] a climb rate to service altitude of 39,000 feet of 16,000 feet a minute – all this in 1944! This allowed the aircraft to swoop from altitude onto the Allied bomber fleet and fire its two 30mm cannon and in later versions also fire unguided rockets from underwing racks. The drawbacks were, however that the fuel only lasted for approximately ten minutes, meaning that the aircraft had to glide back to its base, making it vulnerable at slow speeds to marauding enemy fighters, and the fuel mix itself was so volatile that bumpy landings on the under body skid with a litre or so of fuel remaining could result in the aircraft exploding, or fuel leaks into the cockpit could literally dissolve the hapless pilot even if he was wearing a specially designed rubber flying suit! Notwithstanding these problems, the phenomenal speed and climb capability and potential of rocket powered aircraft still interested many countries, particularly for both the new NATO alliance countries and also the Soviet Union when the Cold War began in earnest in the late 1940’s. The Soviet Union had exploded their first atomic bomb in 1949, and with the unlicensed copies of the Boeing B-29 going into Soviet Air Force service from 1947 as the Tupolev TU-4 ‘Bull’, they now had the potential capability to deliver nuclear warheads at a similar range to those aircraft currently in service with western air forces and particularly the USAF.

Russia's was on the verge of developing supersonic nuclear bombers

Like the USA, it was ‘known’ that the Soviet Union was designing potentially supersonic strategic jet bombers that would cruise at around Mach 1 at 60,000 ft, have an extremely long range, with these aircraft to be in service by the mid 1950’s. The development of interceptor aircraft with a fast rate of climb to altitude and high Mach speed was therefore extremely necessary to NATO to combat the existing and future Soviet strategic bomber threat and were beginning to be developed by various countries, with many looking seriously at rocket power.

An early Saro rocket concept

Although the RAF initially issued a specification F.124T in 1952 for a similar single seat rocket fighter to the Me 163B ‘Komet’ to several companies including Avro who started designing their own aircraft, the Avro 720, the RAF had not thought to include Saunders-Roe.

Coincidentally, although not on this original tender list, Saunders-Roe had at the same time already been making studies of high speed high altitude flight with ideas of a pure rocket aircraft with a 100,000 feet capability. Parallel discussions with the Air Ministry at the same time of the specification resulted in Saunders-Roe subsequently added to the tender list. Their previous research stood them in good stead as they were able to submit their completed project in just one month from the request.

Saunders-Roe, having thought about the design and the specification, were concerned about the launch and recovery system used by necessity by the Komet.

The SR53 in flight

Any aircraft requiring to glide back to a base after a mission as the Komet had had to, with the vulnerability aspect [most Komets shot down had been on a return glide] whilst gliding, the recovery infrastructure required and any potential damage to the aircraft on landing using only a skid system. They therefore suggested that the aircraft be fitted with a small auxiliary ‘get you home’ jet engine to allow the aircraft to return to its own or another base at a reasonable performance. This idea was accepted by the Air Ministry – although why it hadn’t been included in the original specification F.124T is a mystery.

Saunders-Roe had also not been happy with the performance of the projected rocket motors such as the Spectre and Screamer motors so resubmitted their design to allow for their own rocket [to be developed] with an Armstrong Siddley Viper turbojet as the auxiliary power plant.

The Spectre rocket engine under test

In reality, SR had underestimated the time involved in redesigning both the aircraft and their own rocket engine, so they eventually reverted to using a Spectre rocket. The Ministry of Supply issued Saunders-Roe with an Instruction to Proceed on 30 October 1952 for three SR53 prototypes with the capacity to be armed with fifty rocket projectiles in a retractable battery, although this armament specification was changed a month later to replace the battery with two Blue Jay homing missiles.

SR53 armed with Blue Jay missiles

When the final design was accepted, the formal contract for construction of three SR53 aircraft, XD145, XD151, and XD153 was issued on 8 May 1953. The HTP fuel for the rocket motor was giving concern to both the MoS and the RAF, therefore an alternative rocket motor was considered, one powered by liquid oxygen and kerosene in addition to a jet engine. A similar contract was also given to Avro in line with Service ‘belt and braces’ thinking at the time, who designed the 720 delta to be powered by a Screamer rocket engine and the Viper jet engine, with the same armament as the SR53. Although Saunders-Roe had hoped to have a prototype flying by summer 1954, due to delays in the design and the Spectre engine, the first flight didn’t take place until May 1957. In the meantime, knowing that the RAF would probably only choose one of these aircraft due to budget constraints, Saunders-Roe started work on the definitive military version of the SR53.

The SR53 cockpit was state of the art

Maurice Brennan, Chief Designer at Saunders-Roe, had long been in discussion with the RAF regarding radar, as it was accepted that airborne radar would be a necessity for these two aircraft operating at 60,000ft, and Brennan also realised that a far more powerful turbojet would be necessary for the production fighter, now to be called the SR177. The SR177 was redesigned during 1955 to allow for both RAF and RN versions, resulting in an initial development Instruction to Proceed in September 1955. Avro, in the other camp, had also revised the 720 design by late 1954 and had also designed a two-seat all weather Mach 2 variant to cover another specification, with the strong suggestion that they could have a prototype airborne by then end of 1955 – eighteen months before Saunders-Roe!

The design of the SR177 takes shape

Both companies forged ahead with their designs and constructions of the prototypes – the only difference being the fuels for the rocket motors – with Avro still being a year ahead of Saunders-Roe. Each company had their construction problems, but Avro’s 720 was almost complete and would have flown by the end of 1956. The RAF and the Royal Navy wanted the same aircraft, and on paper there wasn’t a lot between the final designs, but the Services couldn’t have both aircraft – something had to give. Having had several serious on board fires on their aircraft carriers revolving around liquid oxygen, the Navy became perhaps understandably nervous about an aircraft [the 720] powered by a liquid oxygen rocket motor. HTP [as in the SR53] rocket fuel was easier to manage both in and out of the aircraft on a carrier, they were also used to HTP as many [then] modern torpedoes were being powered by it, so the Navy made it clear that they would prefer the SR177.

SR177 mockup on the Isle of Wight

So during 1956, the Avro 720 was cancelled as only the RAF would fly her; the determination from the government being that the chosen aircraft would be supplied to both Services. The 720 prototype was broken up, leaving the SR53 test aircraft and production model the SR177 as the only rocket/jet fighter contenders. Saunders-Roe strove ahead with developing the SR53 to flight status, even though the prototype requirement had been reduced by the fiscally aware [sic] government to two aircraft – XD145 and XD151 – and the main production aircraft project, the SR177. By May 1955, the MoS contract had laid out the 177 requirement for both the RAF and RN, with the RAF planning to operate both the new P1 [Lightning] and the 177 in the interceptor roles. The first five pre-production 177’s were to not feature armament or radar and be ready by January 1958, and a formal contract for the initial batch of twenty-seven fully developed Service aircraft to be delivered shortly afterwards was signed in September 1956.

Many nations were interested in the SR177

Although Saunders-Roe had planned a separate assembly at Armstrong Whitworth due to production space constraints at Cowes, this was not specifically for the expected several hundred aircraft on potential order for both the RAF and RN, but this was actually for initial orders which had come from an unexpected quarter. The embryonic reconstituted German Air Force, initially using F-84’s and F-86’s supplied under Marshall Aid from the United States, were looking for their first supersonic fighter to replace these aircraft by the 1960’s, and had been watching the developments at Saunders-Roe with interest from October 1955. Discussions, following an initial reluctance by HMG to discuss aircraft sales with a [recent] former enemy, continued through 1956, particularly as the Germans were looking at an initial potential order of some two hundred 177’s, plus a licence to manufacture the aircraft afterwards. This order could have opened the export floodgates for both Saunders-Roe and Britain, for this aircraft had the potential, like the Lightning, to be in Service use with development for at least the next ten years.

Production underway

These discussions were proceeding extremely well, with the suggestion that deliveries of the RAF, RN and Luftwaffe aircraft would begin by April 1958, with some hundreds being delivered by 1960 with more contracts to follow. Then came the bombshell. The April 1957 Defence White Paper submitted by the Defence Minister, Duncan Sandys, cancelled at a stroke all future manned fighter development for the RAF, including some prototypes already at an advanced construction stage and some already undergoing flying tests apart from the English Electric P1 [shortly to be named Lightning] which was an interceptor already at the flying prototype stage. Sandys had for ten years been fixated on missiles, and thought that these weapons were the only ‘fighters’ Britain would ever need. This meant that the 177 would only be supplied to the Royal Navy and the Luftwaffe. Then in August 1957, Sandys also cancelled the naval version, which meant that the only potential customer would be the Luftwaffe.

SR53 with rocket at low power

Perhaps understandably, the Germans were getting cold feet about the aircraft – after all, if the home country didn’t want their own ‘plane, what was wrong with it and why should we buy it? The Minister of Supply, Aubrey Jones, thinking of the German contract and in defiance of the Defence Ministry, had tried to continue with the 177, but even he had eventually to admit defeat and also admit to the German Defence Minister when pressed at a meeting in Bonn in November 1957 that the programme was only really now a paper one for Britain in the vague and vain hope that the Germans would continue to buy the 177.

The proposed naval SR177

Not surprisingly a month later the Germans officially stated that they were no longer interested in the 177, and immediately signed a contract to buy hundreds of F104 Starfighters from the USA – an aircraft that the Americans didn’t really want for their own Air Force as not many were produced for the USAF, but was an aircraft designed for a similar role to the 177. While the political shenanigans were going on, full test facilities for both aircraft had been acquired and were being made ready at Hurn Airport, Bournemouth while the first flight of the SR53 XD145 took place on 16 May 1957 from Boscombe Down – after the White Paper had been issued. Flight tests carried on throughout the year, including a terrific performance at the 1957 Farnborough Show, even with the Sword of Damocles hanging over the entire project, and she was joined by the second prototype, XD151 in the air from December 8th 1957.

The high-test peroxide fuel was dangerous to handle

Test flying of the SR53 still continued into 1958 even after all parties withdrew their interest whether by choice or by order, until XD151 crashed killing the pilot, Sqn Ldr John Booth DFC. No definitive reason for the crash could be found, so the other SR53 was grounded and eventually found her way to the RAF Museum where she resides today. At Saunders-Roe, a letter from the Ministry of Supply had been received at Cowes on Christmas Eve 1957 [shades and elements of Scrooge?!], formally terminating the contract for the five 177’s which were half-built by that stage. Immediately after the New Year, all jigs and assemblies were dismantled, and the five other 177 aircraft were ready to be scrapped. There was an almost last minute reprieve for the 177 in early 1958 when Japan showed interest and wanted to buy the remaining SR53 and have Saunders-Roe complete two 177’s. As the Government was not interested at this phase, they did not back the plan and Japan consequently bought………the Starfighter, as did the Danes, Italians, Belgians……etc, etc.

The two powerplants of the SR177

At the time of the White Paper, many countries apart from Britain had shown a strong interest in the 177, with what seemed like hundreds of aircraft already destined for Germany, Britain and potentially Japan, let alone the other eventual F104 purchasers. Saunders-Roe and Britain could have broken the US ‘Dollar diplomacy’ hold on Europe’s air forces through the 1960’s and played an important part in continuing a section of our aviation industry for years to come. So how would the SR177, and aircraft with a faster rate of climb and greater ceiling than the Lightning have been used as part of our nation’s defence? Picture the scene… It is 5.30am GMT, Thursday 25th October 1962. It is the height of the Cuban missile crisis, and the world is on the brink of nuclear Armageddon. At the end of the runway at RAF Binbrook in Lincolnshire are two SARO SR177 ‘Eagle’ interceptor rocket/jet fighters of 74 Squadron on Immediate Alert ready to rocket up to between 60,000-80,000 feet at Mach 1.6 in less than four minutes to intercept incoming Soviet Bison and Bear strategic nuclear bombers. The two pilots are Fg Off Ronnie Brinkworth and Fg Off Stuart Stacey, both rather nervous young men on their first tour as Eagle pilots. Ronnie has more than Stuart on his mind at the moment – his brother Ken is a Sub-Lieutenant flying the naval version of the interceptor, the ‘Sea Eagle’, for 806 Squadron FAA on HMS Bulwark as part of the US led naval blockade of Cuba at the moment. The headphones squawk…Luftwaffe ‘Adler’ aircraft [the German version of the Eagle] are shadowing eight Soviet Air Force Myasishchev M-4 Bison bombers at 35,000 ft over the North Sea heading towards Britain – the Adler’s fuel is running low and the Eagles need to intercept and take final action if ordered to. Brinkworth waves good luck to Stacey – they close their cockpit hoods and as they start their jet engine and the rocket engine begins to scream, both pilots mouth a silent prayer…….. Thankfully as we know nuclear war over the international Cuban missile crisis was averted at the eleventh hour, although the ‘Eagle’ [a fictitious name] could have flown, would have been used in that role as front-line defence and should/could have been one of Britain’s successful military exports in the 1960’s.

One of the most beautiful aeroplanes ever made?

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Deborah Hamilton
Deborah Hamilton
Nov 16, 2023

Does anyone know of the F 138 D POSSIBLY AN INTERCEPTOR JET PLANE- i HAVE THE 1956 PRINTED SECRET HANDLING NOTES Saunders Roe- my father worked on it- was it scrapped?

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