Today
we’re taking a look at one of the most promising and interesting prototype aircraft developed by
Britain during the Second World War. Unfortunately, it never saw service,
despite boasting very high performance figures, and this was because of a mix of poor timing,
poor planning, and most of all poor luck – we are of course talking about the Martin Baker MB.5.
This fascinating aircraft was the brainchild of James Martin. He and Captain Valentine Baker
had founded the firm in 1934, and their first design (a light touring aircraft
dubbed the M.B.1) would set the stage for a long string of prototypes well into the
1940s. The lineage of the ‘Martin Bakers’ would mostly consist of fighter aircraft,
the most famous of which originated from an Air Ministry specification that called for
a replacement for the Hurricane and Spitfire - a tall order indeed!
The story of the MB.5 actually begins with the MB.3, which was designed to
meet air ministry specification F.18/39. This called for a high-speed single-seat fighter,
and -with war looming on the Horizon- one that was capable of operating in any part of the world,
regardless of climate. The specification required a top speed of no less than 400mph at 15,000ft,
and it strongly suggested the use of a two-stage supercharger, to get the most out of the engine
regardless of altitude. The armament was expected to be either a pair of 20mm cannons, or eight
.303 calibre machine guns; though the latter were already beginning to fall out of favour, they were
in high supply. As this new fighter was expected to use these guns for either home defence,
or potential escort work, the specification called for a fairly high endurance: two hours of cruising
time, plus an extra thirty minutes at full power to cover take-off and combat time, with a further
30% fuel load held in reserve. This was a lot to ask of any manufacturer in 1939, especially when
performance of the Spitfire was considered the thing to beat for minimum requirements,
but Martin-Baker rose to the challenge. The MB.3, the original attempt to develop
an aircraft for this specification, was -on paper- an incredibly promising design. Firstly,
it was to be equipped with not two, but six 20mm Hispano cannons, each with 200 rounds per gun;
and secondly, it was to be very powerful. The newly developed Rolls-Royce Griffon was to be
the intended powerplant, and with it Martin-Baker predicted a top speed in excess of 410mph at
15,000 feet. Additionally, the MB.3 had been designed to be as easy as possible to
repair and service. Most of the panelling could be easily removed, and the whole thing could be
broken down for easy transport, something that was not possible with the current line of aircraft in
the RAF. With the design meeting the ministry’s criteria, a contract was signed and three
prototype aircraft were ordered as the MB.3. Optimistically, the delivery date for the first
prototype was slated for the end of the year, but as it turned out the
MB.3 would not be completed until much, much later. This was for three reasons.
Firstly, it became very apparent that the Rolls-Royce Griffon would not be ready for use
in time, and so an alternative had to be found. Secondly, Martin-Baker was not a particularly
large company, and completing a full prototype in six months was a huge ask.
And thirdly, by the end of the year, Britain was at war,
and Martin-Baker were quickly swamped with other production orders which took a higher priority.
Because of all this, the MB.3 was still incomplete by mid-1941, and the company
was then informed that there was no longer a need for it and no production orders were forthcoming.
But, seeing as it was mostly complete, they decided to finish the prototype anyway.
By this point it now had the 36-litre 2,020hp Napier Sabre – the same H-24 engine that would
power the Hawker Typhoon and the Hawker Tempest. But, unlike those aircraft, it would not feature
the same chin radiator that made them so recognisable. Martin wanted all the speed
he could get, and to cut down on drag he moved the coolant and oil radiators to the underside
of the wings. Mounting the coolant system in this way certainly cleaned up the aircraft’s lines,
but the Sabre engine repeatedly encountered problems with overheating during tests, a problem
that would eventually have fatal consequences. The prototype flew for the first time on
August the 31st 1942, with Valentine Baker at the controls. flying with ballast to simulate
the weight of guns and ammunition, it immediately demonstrated its potential when it attained a top
speed of 415mph at 20,000 feet. The trials for the MB.3 would continue from August into September,
but then tragedy would strike. On the 12th of September Valentine Baker had just lifted
off when the Napier-Sabre engine failed due to broken sleeve drive crank. Baker
attempted an emergency landing, putting his aircraft down in a field beyond the runway,
but he hit a tree stump (or hay bale, sources conflict on this) and was killed, the aircraft
going up in flames. This event essentially stopped the MB.3 project in its tracks, and Martin-Baker
was now missing one of its original founders. The death of Baker is considered to have deeply
affected Martin - who had been Baker’s best friend and partner since the firm’s inception. As
a result, the trajectory of the company would be altered significantly during the following years;
However, Martin was still determined to build a superior fighter, and carry on
the work that he and Baker had started. He therefor began on a redesign of their MB.3,
making numerous improvements, reengining it with a Rolls-Royce Griffin, and the resulting
aircraft from this would become the MB.5. Design and construction were -in some ways-
remarkably similar to that of the MB.3, but there were of course many changes. The aircraft sported
a tubular steel frame skinned with aluminium panels -most of which were detachable- which
meant that it retained the MB.3s ease of assembly. This would be a strong point of
the aircraft in fact, allowing a very high degree of modularity and repairability,
as aluminium panels (which functioned as the skin of the aircraft) could simply be replaced
if needed and taken off during maintenance by ground crew. The instantly recognisable clipped,
short wings of the airframe were carried on from its predecessor as well, though internally
there were in fact many alterations. The armament was in fact downgraded from
the MB.3, it now had four 20 mm Hispano Mk II cannons, down from six, though the ammo
load would remain unchanged with 200 rounds per gun for a total of 800. The bulk of the systems
would now be operated pneumatically, including the undercarriage, brakes and split trailing
edge flaps - whilst the control surfaces were completely covered in metal, with the exception
of the rudder which was skinned in fabric. The biggest change would of course be found in
the nose. A re-engine was needed, that much had been clear, and the Bristol Centaurus
was briefly considered and plans drawn up (this radial-powered aircraft would be referred to as
the MB.4 but only existed on paper), instead, as previously mentioned - the powerful Rolls-Royce
Griffon would be the powerplant of choice. The Griffon 83 was installed, producing upwards of
2,300hp, and driving two contra-rotating three-bladed propellors.
A popular myth exists that the MB.5 was based on the P-51 Mustang - though there is no supporting
evidence to suggest that this is anything more than just that, a myth. The similar design and
shape of the coolant radiator on the lower fuselage is a contributing factor to the
superficial similarity between the two - but in fact the MB.5 has a drastically different
fuselage and wing construction design to the P-51, and was primarily based on Martin-Bakers
previous line of aircraft which pre-dated the P-51 by years. It was most likely a case
of ‘convergent evolution’ - two high performing aircraft designed with powerful in-line engines
and high speeds at similar times, resulting in similar design choices being made.
In terms of dimensions the MB.5 was comparatively large for an aircraft of its type, at least in
the United Kingdom, with a wingspan of 35 feet, and a length and height of 37 ft 9 and 12 ft 6
respectively. This made it significantly longer than the Spitfire it was intended to replace,
and more akin to the larger single-engined fighters fielded by the Americans – thus adding
fuel to the rumours that part of its design was lifted from the P-51. This made the MB.5 - rather
predictably - quite heavy, weighing in at 9,233lb empty and 11,500lb when fully loaded.
Construction of the aircraft would begin in 1943, though the process would be rather slow
due to other commitments the company had been held to (there was a little something called
the Second World War going on). Frustratingly for the Air Ministry, Mr. James Martin was
apparently something of a perfectionist, as he repeatedly held back the prototype, making small
alterations and tinkering with the design. This tinkering would eventually allow the aircraft
to maximise its performance before its first flight trials, but may have unfortunately been
a contributing factor to the eventual decision to not pursue with further development later one.
As Captain Baker had been the sole test pilot for the company, an outside pilot had to be brought in
for the flight testing of the MB.5 – and this was Bryan Greensted, loaned from Rotol Ltd, a
fellow British aviation firm that specialised in propellors. On the 23rd May 1944 the completed
prototype (given the serial code R2496) would be disassembled and transported to the testing
grounds at RAF Harwell. Immediately - the ability to disassemble, transport, reassemble and fly a
modern fighter aircraft in less than a day speaks volumes about the intelligent engineering that had
gone into the MB.5 (let alone the fact that reportedly reassembly only took one hour),
but unfortunately it would not be all good news for the prototype.
Greensted would in fact be fairly critical of the MB.5 upon finishing the initial flight, mainly
citing some pronounced directional instability. He would go so far as to say the aircraft was a
‘swine to fly’ - hardly encouraging words after such a lengthy development program. Martin
however, was not discouraged, and he got to work drawing up some changes to remedy the aircrafts
deficiencies based on careful analysis of Greensteds detailed flight report. It was
found that the large, contra-rotating propellors reduced the authority of the rudder, which had
remained virtually unchanged from the MB.3 - so to combat this Martin would refit the prototype with
a significantly taller vertical tail surface. This modification took almost six months to complete,
owing to testing varying rudder sizes, but when Greensted flew the MB.5 again the handling
had improved dramatically. In terms of performance, the aircraft was
highly praised - recording a top speed of 395 mph ( 636 km/h) at sea level, which rose to 425
mph (684 km/h) at 6,000 feet and finally 459 mph (740 km/h) at 20,000 (though the aircrafts service
ceiling stood at up to 39,000). It climbed pretty quickly; In 6.5 minutes the aircraft could reach
20,000 feet, which was roughly on par with comparable late-war propellor driven fighters,
but the acceleration was considered to be one of the few short-comings (along with some lingering
directional instability), due to the high weight of the aircraft - though conversely this also
gave improved acceleration in dives, which allowed the aircraft to reach extremely high
speeds - which by all accounts it excelled at. Range and endurance was also reviewed favourably,
The 750 litre fuel capacity (housed in two tanks in front and behind the pilot) allowed a range of
up to 1,120 miles. Additionally the spaced-out design of the undercarriage (like that on the
MB.3) gave a much safer and robust landing performance to the MB.5 when compared to the
narrow-track undercarriage of the Spitfire. As an added bonus the contra-rotating propellers
negated the problems caused by engine torque; This improved control on the ground and in the air,
as the aircraft wasn’t pulled by torque to one side like on a conventional single
propellor fighter, and this would have made the MB.5 easier to learn for inexperienced
pilots…had it entered service perhaps two years earlier to actually be useful.
In the closing months of 1944, with barely 40 hours of flight time logged on the MB.5,
the Air Ministry informed Martin that they would not be pursuing further development
or placing any production orders for the aircraft. This was unfortunately a case of
supply and demand- the war in Europe was winding down and the RAF did not
urgently need a new generation of fighter designs - and when they did it was becomingly increasingly
obvious that the new generation would belong to jet-powered aircraft; in fact, some were already
in development. And so, the MB.5 was relegated to a life of testing and public exhibitions.
Among these, During 1945, the MB.5 would take part in a demonstration in front of Winston Churchill
at Farnborough, but it had the misfortunate timing of suffering an engine failure mid-flight.
Following this near-miss, it was operated more conservatively over the next 18 months,
being flown by a variety of test pilots and accumulating just a further 40 hours of
flight time. Though little used, During this time, and in the following years,
it received almost universal praise from whoever had a chance to fly it. In June 1946 the aircraft
would return to Farnborough and take part in an aerobatic show in the hands of Polish Squadron
Leader Jan Zurakowski, a man famous for this aerobatic skills, and one that would proclaim
that the MB.5 was the finest he had ever flown! In further testing throughout 1947 the MB.5 would
be flown by Wing Commander Maurice A. Smith, at de Havilland at Hatfield,
before again returning to RAE Farnborough. At Farnborough the aircraft would then be flown by
Captain Eric ‘Winkle’ Brown, a pilot famous for his wartime service and his legendary career as
a test pilot. Brown would mirror the opinions of his peers, complimenting the aircrafts impressive
top speed and handling - saying and I quote: “In my opinion this is an outstanding aircraft,
particularly when regarded in the light of the fact that it made its maiden flight as early
as 23rd May 1944”. Despite his high praise he did maintain that the aircrafts biggest
vice was still its directional instability - a trait which apparently the enlarged vertical
stabiliser had not completely fixed. By this point the MB.5 was in its autumn years.
For the next two years of its life it would be moved to the Air Ministry Servicing Development
Unit at RAF Wattisham and used predominantly as a training and testing airframe until 1950. Then it
was relocated to RAF Bircham Newton, where the much-loved but unfortunate MB.5 (now a six year
old airframe) would meet its ultimate demise: it was used as a ground target in training exercises
until 1963, when what was left of it was then burned. It was a negligent and undeserved end
to such a historically interesting aircraft, one that should probably have been preserved and stuck
in a museum, Unfortunately, this means that today we have only a replica, built in Nevada, United
States, which was built 2 metres shorter than the original and used the wings of a P-51 Mustang.
Had the MB.5 gone into service it would have been one of the fastest combat aircraft in the
world - but sadly it was not to be, simply too late to garner interest, and eighty years on we
can only speculate on what might have been had it been built a little bit faster.
The location of Captain Valentine Bakers crash-site was found in December of 2020,
and is located on Aylesbury Vale Golf Club. A memorial of Valentine Baker along with a bust
of him was erected there and is now open to the public, along with a further memorial at RAF Wing
next to the hangar where the MB.3 was stored. After a few more ventures into aircraft
design (the post-war jet-powered MB.6 and 7) Martin-Baker as a company would produce no more,
and Martin - as a result of Bakers death - would reorganise and dedicate his company and the rest
of his life to the design and production of aircraft ejection systems to save pilots lives,
which is what the company is famous and still successful for today.
As always, thank you all so much for watching, and a big thank you of course to the Patreons.
You know I finally believe we are back onto a regular video schedule again,
long may it remain so. There may not be an upload this coming Wednesday,
as I am hoping for a long video to be ready for next weekend, but we’ll see how things
pan out. A big shoutout of course to the wing commander tier patrons, our highest tier members,
and a special thank you to Jason Du Ban who is the newest member of this special group.
Patreon has been a bit slow with updating details on my end, so if anyone is missing
from these lists I apologise, and hopefully it will all be up to date next week. But as
always thank you all for your continued support, and I’ll catch you all next time. Goodbye.