The Westland Welkin; Whirlwind’s High Flying Sibling

January 31, 2023

If you’ve been watching my YouTube channel or reading this website for a while, you’ll know I have done a couple of articles on the Westland Whirlwind, an interesting aircraft that, though it provided good service as a ground pounder, never met its potential as a fighter. Much of this is attributable to problems with the Whirlwinds powerplant, propellors and cooling system and these curtailed the Whirlwind’s combat career.

But there has always been this persistent theme in aero head discussion circles about a bit of a “what-if” situation. Had Westland fitted the famed Rolls Royce Merlin’s to the Whirlwind, what might it have achieved?

Well, here’s the thing. They did…. kind of.

Say hello to the Westland Welkin.

This was effectively a next stage evolution of the Whirlwind, though with a very specific role in mind. Because though the Whirlwind would eventually make itself useful as a ground attack aircraft, the Welkin was all about altitude. Indeed, the name Welkin comes from an old English word that means “Cloud” or “Firmament” and the aircraft was developed to deal with a very specific threat.

In August 1940 the Luftwaffe began utilizing Junkers Ju-86P high altitude reconnaissance aircraft over the British Isles.

This aircraft, with its pressurized cabin, enlarged wingspan and Jumo 207 diesel engines, was capable of flying at 39,000 feet (c.11,900m), which was beyond the interception capabilities of any British fighter flying at the time. From such high altitudes the Ju-86P could conduct photo reconnaissance of British defences and, on occasion, drop the odd bomb or two, though not with any great accuracy.

But the threat was enough to goad the Royal Air Force into seeking a solution. Having German aircraft flying with impunity was obviously an operational nightmare, and there was also the concern that the Germans might begin to field fleets of high-altitude bombers that would be immune from interception completely. Instructions were therefore issued for the development of a high-altitude interceptor that would be able to engage the threat.

Indeed, there had been proposals for such an aircraft even before the war began, and as a result two aircraft were put forward for the RAF specification, the Westland P.14 and the Vickers Type 432.

 

The latter, which was nicknamed the “Tin Mosquito” because it did indeed have a resemblance to the De Havilland aircraft of that name, was a very interesting aircraft but ultimately had issues that led to it not being selected.

With the P.14, subsequently named the “Welkin”, by contrast Westland seem to have been able to learn from the lessons – and mistakes – of the Whirlwind’s development.

 

Indeed, the aircraft shared the same designer, Teddy Petter, and no doubt he was able to draw on his recent experiences with the Whirlwind, hence the family resemblance.

But though it’s easy to see the Welkin as an enhanced version of the Whirlwind, it was a unique aircraft, being a tremendously complex project for its day. For starters, instead of the troublesome Peregrines of the Whirlwind, the Welkin did indeed use Rolls Royce Merlin’s, though advanced versions fitted with two-stage superchargers that would allow the aircraft to operate at extreme altitudes.

The P.14 was ordered in January 1941 and would fly for the first time in November 1942. This was equipped Merlin 61s, the same as would be fitted to the Supermarine Spitfire Mk.IX, and the subsequent production aircraft would be fitted with Merlin 76 and 77’s that rotated in opposite directions and so countered engine torque.

The Welkin also had an extremely strong cockpit construction to allow for pressurization, including a double-skin Perspex canopy that had warm air blown between the layers to prevent freezing over. The pressurization was however not perfect, and cabin altitude was set at 24,000 feet (7,300 m). This in turn meant that the pilot needed to wear an oxygen mask despite pressurization and a high-altitude survival suit if he had to bail out.

Another notable change from the Whirlwind was the altered armament layout. Though the Welkin retained the four 20mm Hispano cannon of its predecessor, these were moved from the nose to a belly tray under the aircraft. This had the advantage of enabling the aircraft to carry more ammunition, be serviced more easily and allowed the pilot’s position to be moved further forward than in the Whirlwind, improving visibility.

But the most notable visual difference between the Whirlwind and the Welkin, was the size difference, because the Welkin was absolutely massive.

The Whirlwind had a wingspan of 45 feet (13.72 m).

 

The Welkin’s was 70 feet (21.34 m).

 

That’s only a foot shorter than the wingspan of a B-26 bomber!

Of course, the Welkin needed those massive wings to maintain stability at the high altitudes it was intended to fly at, with the aircraft having a cited service ceiling of 44,000ft (13,000 m). Testing showed that the aircraft had pretty good performance, not just hitting the required altitudes but also making a top speed of 385mph (620km/h).

 

However, the long wings did mean that it wasn’t a particularly agile aircraft, with a slow roll rate. Hardly a surprise as the Welkin was not designed to be a dogfighter after all.

But the wings would throw up an unforeseen problem. To make sure it was strong enough to support itself, it was made with a high thickness-to-chord ratio, that is the thickness of the wings against their length. And this led to a problem that was then becoming more and more prevalent in aircraft – compressibility stalls in a dive.

Once the Welkin hit around 500mph (805km/h) the aircraft started to vibrate heavily. Indeed, Westland’s test pilot, Harald Penrose stated that in its “milder” forms at the start of compression, the aircraft acted like “…tobogganing down a flight of stairs on a tea tray.”

I dread to think what the Welkin must have been like when it experienced serious compressibility issues.

Penrose also encountered another issue which proved an unexpected hazard. In early testing the pressurization system heated the cockpit up tremendously, causing Penrose to sweat profusely. He then contracted pneumonia during the Welkin’s testing program, which he asserted was because of getting out of the boiling hot aircraft into a freezing cold wind after landing.

Certainly his accusation was taken seriously enough that Petter reworked the pressurization system to run at a much cooler level, and when he had recovered and resumed working on the Welkin, Penrose reported it was now a very comfortable aircraft to fly.

The compressibility issue would never be resolved as it was soon recognized as being intrinsic to the design and something that pilots would have to deal with. S

So it was that the Welkin was ordered into production and officially entered into service with the RAF in May 1944. Which is somewhat strange because by then it was basically completely redundant.

As said, the Welkin prototype first flew in November 1942. But in August 1942 Junker Ju 86Rs began nuisance bombing raids over Southern England. Although only dropping single bombs on occasional targets as they trawled slowly overhead, this was enough to put the Air Ministry into a frenzy and they ordered a solution be found as quick as possible.

The first step was the building of the De Havilland Mosquito Mk XV, which was a rapid conversion of this ever adaptable aircraft that allowed it to get up to altitudes above 40,000 feet.

 

And it shows how important this was considered because the first Mosquito Mk.XV protype flew only about three weeks after the Junkers made their first raid, and the type was in service by early February 1943!

But in fact even this turned out to irrelevant because on September 12th, 1942, a specially modified Spitfire Mk.IX managed to intercept a Ju-86 and commenced a running fight with it all the way up to 44,000 feet (13,411m). The Spitfire didn’t manage to destroy the Junkers, but that was probably for the best because the Germans realized that their high-altitude tactic had already been countered and, with only a literal handful of the specially converted Ju-86s ever made, decided not to risk them over the British Isles again.

So, as said, when the Welkin finally entered service, it was really kind of surplus. Indeed, to say it entered service at all is open to interpretation, as though the aircraft was officially on the books with the RAF, only two ever flew in service, and that to conduct specialist testing in high-altitude tactics.

A second model, the Welkin Mk.II was also developed, which was a two-seat radar equipped night interceptor, but this ultimately was limited to single prototype being built.

 

All told seventy-seven flyable Welkin’s were built, made up of the P.14 and the Mk.II, and seventy-five production Mk.Is. Another twenty-six aircraft were constructed which never received engines, and all of these aircraft would go to the scrap yard fairly quickly, with the type being officially retired from British service in November 1944, a mere six or so months after entering it.

So, the Westland Welkin is a bit of an oddity. It was an extremely advanced and challenging technical project that actually came together remarkably trouble free considering, with the issues that the aircraft encountered pretty much par for the course in developing technologies that pushed the very boundaries of what was known in aeronautics at the time.

It also seems to have been capable of performing its extremely specialist role satisfactorily, but by the point it was available to do that mission it wasn’t really needed because other aircraft already in production could manage it, even if needing modifications. Despite that, it still got a limited production run and service life.

One suspects it was allowed to continue development and enter production because the British authorities didn’t want to get caught out by the sudden appearance again of more super high-flying bombers as had occurred in 1942. After all, if the Germans had pushed even higher, maybe a botched together Mosquito or Spitfire wouldn’t be able to do the job, and the specialist Welkin would be needed.

Regardless, by 1944 the Air Ministry and RAF were evidently confident that the threat had passed and so had the need for the Welkin.

However, it wasn’t all a wasted effort. Just as Teddy Petter seems to have learnt from the Whirlwind in his developing the Welkin, so to his experiences with the Welkin helped him develop his next aircraft.

The English Electric Canberra.

This notably had a much better wing thickness to chord ratio, and subsequently would prove an excellent aircraft that saw widespread service with multiple users all over the world.

So, though the Welkin may not be as well remembered as either its Whirlwind forebear or Canberra descendent, nor saw anything like their service, it still played an important part in post war aviation development.

Sources/Related:

https://en.wikipedia.org/wiki/Westland_Welkin

https://www.militaryfactory.com/aircraft/detail.php?aircraft_id=523

https://www.historynet.com/scaling-new-heights/

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