The autumn of 1941 saw the introduction of
a new British aircraft, the Hawker Typhoon, a highly advanced fighter that promised
to reach unprecedented speeds thanks to its innovative and powerful Napier Sabre engine.
But the Typhoon had been rushed to the frontlines and had serious teething problems.
The most serious of those was that it suffered from structural failures.
But for us today, the focus will be on another problem: its overly thick wing.
This wing had a very good behavior at lower speeds and plenty of room for fuel and armament,
but close to the Typhoon’s maximum speed, there was a very sharp increase in drag, leading
to vibration and instability. This phenomenon is known in aerodynamics as compressibility and is
related with speeds approaching the one of sound, but it was rather unknown when the
Typhoon was initially designed.
Noticing this, as early as mid-1940, the Hawker
Company and its lead designer, Sidney Camm, started working on a new, overhauled wing. This
new wing was thinner, with a much reduced maximum thickness to chord ratio, and the point of maximum
thickness was pushed further back upon the wing.
The upper surface was also smoother, and the
planform was changed to a semi-elliptical with an overall increase in area. These changes were in
line with what can be called a laminar flow wing, commonly associated with the P-51 Mustang.
The result was an improvement in performance, stability, and handling at high speeds, as well as
a reduction in vibration, allowing for excellent diving characteristics. On the negative
side, the new wing had less room for fuel, which had to be stored in a new tank in the
fuselage, requiring a more forward positioning of the engine and an increase in length.
Plans for this thin-winged Typhoon led to the creation of Specification F.10/41 by
the Air Ministry, issued on August 1941 and asking for two prototypes of what was
called, at this point, the Typhoon Mk II.
Beyond the wing, the upcoming aircraft
was also to have a very dramatic change: the removal of its "chin" air intake. The plan
was to fit the air intakes for the radiator and oil cooler in the wing roots, similar to what
De Havilland had done with its famous Mosquito. This change required an upcoming version
of the Sabre engine, the Sabre Mk IV.
But the Mk IV was troublesome, and in the
spring of 1942, it was decided that further engine options would be desirable. Consequently,
in June, the number of prototypes required was increased to six, and in August, the whole project
became more defined. First and most importantly, the Typhoon Mk II was renamed Tempest. Officially,
this was because enough changes had been made from the original to merit a new name, but this
might have had political reasons as well, since the Typhoon had acquired a very bad
reputation among pilots, in no small part thanks to the structural failures. The various
engine options were also given Mark designations.
The Mark I was to be the originally
planned version with the Sabre Mk IV and the wing root air intakes.
The Mark II was to be powered by the upcoming Bristol Centaurus Mark IV radial engine.
The Mark III and IV were to receive the upcoming Rolls-Royce Griffon in the IIB
and 61 versions, respectively.
Finally, the Mk V was to become a sort of
Plan B, using an already available engine, the Sabre Mk II, which was being used
in current versions of the Typhoon.
As commonly happens during wartime technological
development, most of these plans never came to be. The Mk I prototype would eventually achieve
astonishing performance, reaching a speed of 472 mph (759.61 km/h), before it was cancelled
in late 1943 due to reliability problems with the Sabre Mk IV engine. The Griffon-engined
prototypes would stay that way, as the new Rolls-Royce engine was reserved for different
aircraft, most notoriously the Spitfire.
So, of these planned variants, the only two that
would see production were the Mk II and the Mk V. But it would be a while until the Mk II was up and
running, and we’ll get to it later in this video. In a confusing way, the first Tempest to become
available was the much more conventional Mk V, which kept the Typhoon’s chin air
intake and Sabre Mk II engine. Despite these similarities, it had many
changes, the most important being:
- The overhauled wing,
- A tail of overall increased area with a fin to improve stability,
- A bubble canopy, which would later figure on the Typhoon too,
- and a four-bladed propeller.
The Mk V took to the skies for the first time
on September 2, 1942, followed by a period of improvements until the first production
example was ready to fly on June 21, 1943. The first 100 to leave the factories were
called the first series. Those were distinguished from later Tempests by their armament, as
they had four Hispano Mk II 20 mm cannons, which protruded from the wing leading edge,
unlike the second series, that used the improved Mk V with a better rate of fire and a smaller
size. In addition, the first series Tempests couldn’t carry drop tanks, bombs, or rockets.
In January 1944, the Air Fighting Development Unit (AFDU) received and tested the Tempest. There
it was found to be much superior to the Typhoon, as it was faster at all altitudes, a
better climber, much superior on a dive, much more stable at higher speeds, and with the
recent addition of spring-tab ailerons, it also had a superior roll rate. The only drawback seemed
to be a lower fuel capacity, but which translated to about the same range since the Tempest had
better aerodynamic properties. When tested by the same unit against other aircraft, both allied and
German, the Tempest was considered, in general, superior up until altitudes of 20,000 ft.
But why only up to that altitude? Well, the Sabre was an absolutely ground-breaking engine
that would shatter the 3,000 hp barrier after the war. But as with any technology that truly is
ground-breaking, the Sabre’s initial years were troublesome. As such, Napier spent much time
ironing out its problems and was unable to develop the engine’s supercharger to the optimal
point. In any case, certainly not to the point that Rolls-Royce perfected the Merlin’s. So, both
Typhoon and Tempest struggled at higher altitudes. But it quickly became clear that the new British
machine had everything to be a fantastic fighter aircraft at medium to low altitudes.
In the early days of 1944, the first Tempests were delivered to a frontline
unit. The first two squadrons do receive them were the No. 3 RAF and the No. 486 of the
Royal New Zealand Air Force. In April 1944, the British fighter started its operational life,
initially supporting simple rescue missions.
The plan had been to have a full wing of
Tempests before the Normandy Landings, but delays meant that No. 56 Squadron, the third
in line, wouldn’t get them until late June, and so, a wing with only two Tempest squadrons was
created on April 1944 and named the No. 150 wing, based at the RAF Newchurch airfield in Kent. It
was placed under the command of Wing Commander Roland Beamont, who would become a legend.
The Tempest’s gradual introduction continued until D-Day when the Newchurch wing was assigned
to provide air cover over the beachheads. But the Luftwaffe was nowhere to be seen on June 6, and
the first air victory by a Tempest wouldn’t come until June 8, when 9 Tempests clashed with
7 Bf 109s while making a sweep over Rouen, in northern France. The skirmish ended
with three Bf 109s shot down and a single Tempest lost due to engine trouble.
But despite this successful introduction, the No. 150 Wing was pulled back and reassigned
to the Air Defense of Great Britain to counter a new threat, that of the Fiesler Fi 103
Flying Bomb, better known as the V1.
Launched from Northern France and crossing the
channel at very low altitudes and high speeds, the diminutive V1s were extremely hard to see and
intercept. But what the Tempest didn’t lack was speed at low altitudes, and on June 16, the
No. 150 Wing was used on the first so-called "diver" patrol, where 13 V1s were claimed. By
mid-August, this number had risen to more than 600, and the Tempest proved to be the best V1
killer, especially thanks to its great stability at high speeds. The V1 crises continued until
mid-September, when improvements to air defense, especially in how AA guns and radars worked
together, made them less of a threat.
In the meantime, a second Tempest wing had
been created after three more squadrons converted to the new fighter. Freed from the
anti-V1 role those flew missions in support of Operation Market Garden in the second
half of September, eventually leading to the reassignment of five squadrons to the 2nd
Tactical Airforce by the end of the month.
After some base hopping, they ended up at Volkel,
the most advanced airfield on Dutch soil, where they would remain for six months and take part
in the hard fighting in the Rhine area. There, the Tempest was able to face the newest German
fighters, such as the Focke-Wulf Fw 190D-9, the version with an inline engine,
and the brand-new jet aircraft that were appearing in increasing numbers.
One proof of that was the event on February 11, 1945. Squadron Leader David Fairbanks was
performing an armed recon mission near Hanover when he spotted a Me 262 and chased it for about
20 miles, going in and out of clouds. The German pilot, Hauptmann Hans Felde, seemingly thought
he had lost the British pursuer and approached to land on the Rhine airbase. Fairbanks caught
the German jet extending the landing gear at low speed, the point where jet aircraft are most
vulnerable. A short burst was enough to set it ablaze, causing it to crash in the middle of
the runway. The claim that day was for a Me 262, but this was in fact a new and emerging
threat, the jet bomber Arado Ar 234. It seems this was the first time one
was shot down by an allied aircraft.
David Fairbanks, an American, would
become the highest-scoring Tempest ace with at least 11 victories.
This fantastic custom-made work of art was created by the very talented Anastasios
Polychronis. Let us know what you think of it!
Beyond its role as a fighter, the Tempest
also had a great impact on the ground attack department. During a typical armed reconnaissance
mission, Tempests were used to strafe and destroy locomotives, vehicles, and aircraft on the
ground. These operations were extremely costly, and many Tempests were lost to AA fire. In
fact, that and engine malfunctions seem to account for most of the 155 Tempests lost
to all causes while operating under the 2nd Tactical Air Force. In that period,
240 aerial victories were claimed, giving the Tempest a positive kill ratio, described
in some sources as being as good as 7 to 1.
When Germany surrendered, only 8
squadrons were operating the Tempest Mk V, as conversions had been canceled due to a new
version of the Tempest becoming available.
Seen as the definitive Tempest, the Mk
II had first flown on June 28, 1943, but severe problems with engine vibration had
delayed it considerably. Powered by the 2,520 hp air-cooled radial Bristol Centaurus,
the Mk II impressed by reaching 442 mph, over what the Mk V could do. It also outclimbed
the older variant, reaching 15,000 ft in 4.5 minutes. But the first Mk II had only left the
factories on October 1944, much later than planned and too late to play a part in the War in Europe.
So, in April 1945, these were sent to Khartoum, Sudan, to take part in tropical weather trials
in preparation for service in Southeast Asia. While Germany had surrendered, Japan was still
fighting, and the British and Commonwealth nations were assembling a new force to fight in Asia.
But the Japanese surrendered before the Mk II saw action leaving the Mk V as the only variant
to see battle during the Second World War.
Post-war, another version was also
produced in some numbers, the Mk VI. This had the Sabre Mk V engine and had the
carburetor air intakes moved to the wing root, as had been the plan with the original Mk I. In
total, 1399 Tempests of all variants were built.
The Tempest would also lead
to another legendary aircraft, the Hawker Sea Fury. Widely considered one
of the best piston fighters ever made.
The Tempest arrived too late to
make a big difference in the war, and the Allies would’ve undoubtedly won World War
Two with or without it. Nonetheless, I call it a war-winning aircraft, as, had the war lasted
longer, it would’ve proven to be invaluable. In that sense, I believe the Tempest to be among
the best low-altitude fighters of the period, even though other great aircraft can claim that
mantle, for example the German Fw 190 Dora Nine.
As the pinnacle of piston-powered fighter
aircraft, the Tempest and its successor, the Sea Fury, also raise an unanswered
question. Did we ever reach the full potential of piston-powered military aircraft?
This question became moot since, meanwhile, the jet engine era began. But what is your
opinion? Let me know in the comments below.
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