Short Stirling

[Acheron]

I would like to talk about the Short Stirling,. On wikipedia I read, that it was required to have a narrow wingspan to fit into exisitng hangars back then, compromising its performance. So far so good, but then I come across this image, also on wikipedia:

I can't help but notice that the Stirling has only 89 centimeters less wingspan than the Lancaster and actually 8 cm more than the Halifax. So I am confused by the previous statement. Did they mean that the Stirling should have had an even larger wing than the others? It look bigger on the sideview.

Two other points, I read that the ceiling of the aircraft was abysmal, for example unable to fly over the alps, instead having to fly through them. On the other hand, I also read that it was surprisingly maneuverable, able to outturn heavier fighters, I assume like Ju-88 long-range-fighter variants? Are these stories true?

 

[nuuumannn]

On wikipedia I read, that it was required to have a narrow wingspan to fit into exisitng hangars back then, compromising its performance.

i wouldn't believe everything you read on the internet There is quite a bit on this subject floating around on the net, but a few facts. The wingspan restriction was not specifically about RAF hangars. The specification for the aircraft, B.12/36 states the following:

"An aircraft fulfilling these requirements will probably be large, but it should not exceed a span of 100 ft."

There is no mention of a stipulation of span due to hangar size. It's worth noting that, putting this into perspective for the time, 100 feet was a large span compared to existing bomber aircraft; the RAF's in-service bomber was the Handley Page Heyford, whose span was 75 feet and the Harrow, which entered service a year after B.12/36 was issued had a span of 88 feet, so 100 feet was a big aeroplane by the standards of the day.

There were issues that affected the Stirling's development, weight creep was one of them, aside from the Air Ministry making changes to the specification and Short Brothers discovering mid development that the wing's angle of incidence meant that the aircraft would have a very long take off run, which was discovered during the testing of the small scale prototype S.31, but by that time the prototype was already underway and it was far too late to be able to do anything to change the incidence, or indeed the span, so Shorts extended the undercarriage to give it a greater angle to compensate. Increasing the span would have exceeded the 100 foot limit and added extra development time, as well as weight, so they went with what they had.

That's a grossly simplified version of events, but that is essentially the story behind the Stirling's wingspan, which wasn't actually that short compared to its contemporaries or its predecessors, but the Stirling itself was such a big beast comprised of a lot of metal that really could have done with a greater span.

 

[tomo pauk]

I would like to talk about the Short Stirling,. On wikipedia I read, that it was required to have a narrow wingspan to fit into exisitng hangars back then, compromising its performance. So far so good, but then I come across this image, also on wikipedia:
I can't help but notice that the Stirling has only 89 centimeters less wingspan than the Lancaster and actually 8 cm more than the Halifax. So I am confused by the previous statement. Did they mean that the Stirling should have had an even larger wing than the others? It look bigger on the sideview.

Two other points, I read that the ceiling of the aircraft was abysmal, for example unable to fly over the alps, instead having to fly through them. On the other hand, I also read that it was surprisingly maneuverable, able to outturn heavier fighters, I assume like Ju-88 long-range-fighter variants? Are these stories true?

Merely an attempt to balance out the shortcomings with invented truths.
Instead of noting that designers made too big and heavy fuselage, author(s?) pointed finger into other direction. Same with the purported maneuverability, to remove the attention of the fact that ceiling was too low (it was too low due to very high wing loading).

Myths were/are abound. Just recently no less than Elon Musk and his main engineer at SpaceX said that the best Merlin was the version with turbocharger that made in the USA. German author noted that Ju 288 was a symbiosis of Jumo 222 and the airframe, even though the Jumo 222 was a dumpster fire. Russian Wikipedia notes that Yak-3 was a key to the Soviet air superiority over Kursk in 1943, even though the prototypes of Yak-3 were flying 1st at winter of 1943/44. Defiant making the supposed kills of Bf 109s that Luftwaffe never suffered. Zeros killing Spitfires above Ceylon in 1942. Greg at youtube with claim that Merlin became great only when the US carb was fitted on it, when used US fuel, and when it had the supercharger that originated from the USA.

 

[nuuumannn]

Just as an addition to that, it's worth noting that Handley Page lengthened the Halifax's span during its development so that it exceeded 100 feet. In the Halifax III, which was a modified B.II and became the most produced variant, the span was 104 ft 2 in. This became the standard for Halifax marks following the B.III.

 

[Graeme]

Myths were/are abound. Just recently

Long live the myth!
This is Key Publishing 2021...

 

[GrauGeist]

Starting in the 1930's, the RAF had hangars with openings well over 100 feet, like the "C", "J" and "K" types.

It would be refreshing if publications didn't use wiki as a source of info and actually did some research.

 

[33k in the air]

"The Air Staff require a heavy bomber for world-wide use, an aircraft exploiting alternatives between long range and very heavy bomb load made possible by employing catapult launching in overload condition. The aircraft must possess high performance but at the same time have strong defence in all planes.

"An aircraft fulfilling these requirements will probably be large, but it should not exceed a span of 100 ft. In order to maintain maximum reliability during, and immediately after catapulting, and also to be able to retain height with one engine out of action, the aircraft should be four engined. Since it will be required to operate from bases anywhere in the world, the aircraft must possess facilities for maintenance in the open."

Thus ran the preamble to Specification B.12/36 from which the Stirling stemmed.

--- The Stirling Bomber by Michael J.F. Bowyer, p.21

Short's worked along the lines of a landplane Sunderland. To speed the project, a span of 112 ft. was chosen. The company were relying on years of experience with large aircraft, a few of them landplanes.

The Air Ministry's wingspan limitation was based partly upon hangar size, but there was more to the restriction than just that. They feared the B.12/36 might become very large and unwieldy, and require long runs. Acquiring land for new airfields was meeting opposition, and it was deemed unwise to opt for very large aircraft. Accelerated take-off also imposed weight limitations. Therefore they turned down Short's first scheme, and B.12/36 had to conform to the 100 ft. span.

--- The Stirling Bomber by Michael J.F. Bowyer, p.24

 

[nuuumannn]

This is Key Publishing 2021...

There goes that Ken Ellis again...

(for those of you not sure who that is, Ken was the brainchild behind British aviation tabloid FlyPast magazine, which began back in the 1970s; Ken deciding that the UK at that time did not have a good representative historic aviation magazine and, having an interest in aviation preservation, being responsible for the Wrecks And Relics series that counted surviving historic and derelict airframes in the UK, decided he'd act and create his own magazine. He had a great editorial team working with him for years, The late Ken Delve and the Late Robert Rudhall and himself. At the time the product of this dynamic trio was known as "ByPass Magazine" owing to the fact that all of them had had heart bypass operations!)

 

[Thumpalumpacus]

I've got some de ja vu here.

 

[GrauGeist]

Martin Caidin got his start as a magazine editor.

Without that stroke of luck, we wouldn't have been blessed with "Caidinisms"...

 

[tomo pauk]

Long live the myth!
This is Key Publishing 2021...

I didn't say that the Air Ministry wing span requirement was a myth.
What I'm trying to point out was that the too big, heavy and draggy fuselage was the culprit to the Stirling having low performance. Fuselage desing was what Short did (not AM), so all credit and criticism is only theirs.
The big wing (area ~20% greater than on the Halifax or Lancaster) again added to drag and weight. Again, the wing area was designer's choice (not the AM requirement), the weight of fuselage driving the wing area upwards.

 

[TheAircraftBuilder]

I didn't say that the Air Ministry wing span requirement was a myth.
What I'm trying to point out was that the too big, heavy and draggy fuselage was the culprit to the Stirling having low performance. Fuselage desing was what Short did (not AM), so all credit and criticism is only theirs.
The big wing (area ~20% greater than on the Halifax or Lancaster) again added to drag and weight. Again, the wing area was designer's choice (not the AM requirement), the weight of fuselage driving the wing area upwards.

I'd read the engine choice possibly didn't help - Hercules radials were not generally seen as having enough grunt at higher altitudes. Proof of this can be found with the Lancaster II (Hercules engined) vs. Lancaster I/III (Merlin) - the former struggled at altitudes and suffered in terms of range/payload.

As you correctly state though - the ideal is having an aerodynamic airframe combined with powerful yet efficient engines (B-29 in my opinion being the pinnacle in that regard during the WW2 timeframe).

 

[tomo pauk]

I'd read the engine choice possibly didn't help - Hercules radials were not generally seen as having enough grunt at higher altitudes. Proof of this can be found with the Lancaster II (Hercules engined) vs. Lancaster I/III (Merlin) - the former struggled at altitudes and suffered in terms of range/payload.

We can recall that Halifax was an useful bomber when powered by Hercules engines, and was pretty bad with Merlins on board.

 

[Graeme]

I didn't say that the Air Ministry wing span requirement was a myth.

I never said you did Tomo. I'm referring to the Hangar part of the specification story for the Stirling - that's a myth. There's an interesting thread on PPruNe attempting to pinpoint were it came from and one suggestion was the commentary section of the instruction leaflet for the Stirling Airfix kit - circa 1966. The Wiki article gives it to Geoffrery Norris. Colin Sinnott, who wrote a thesis on RAF Operational Requirements 1923-1939 suggests it started much earlier and believed by RAF personnel at time of the Stirling's debut. Either way, it's persisted for decades and hard to shake and as illustrated above - a few more below from various decades.

 

[tomo pauk]

I never said you did Tomo. I'm referring to the Hangar part of the specification story for the Stirling - that's a myth. There's an interesting thread on PPruNe attempting to pinpoint were it came from and one suggestion was the commentary section of the instruction leaflet for the Stirling Airfix kit - circa 1966. The Wiki article gives it to Geoffrery Norris. Colin Sinnott, who wrote a thesis on RAF Operational Requirements 1923-1939 suggests it started much earlier and believed by RAF personnel at time of the Stirling's debut. Either way, it's persisted for decades and hard to shake and as illustrated above - a few more below from various decades.

Thank you for all these excerpts.

A lot of people were pointing out the wing span + hangar thing. Unfortunately, the reasoning for such a big, draggy & heavy fuselage, (that was also a driver for wing area required, that in return pushed upwards the weight and drag of the wing, too), is seldom mentioned.

 

[Howard Gibson]

Thank you for all these excerpts.

A lot of people were pointing out the wing span + hangar thing. Unfortunately, the reasoning for such a big, draggy & heavy fuselage, (that was also a driver for wing area required, that in return pushed upwards the weight and drag of the wing, too), is seldom mentioned.

I am looking at Profiles for the Short Empire flying boats, the Short Stirling, and the Short Sunderland, all written by the aforementioned Geoffrey Norris. All the wings were intended to be identical, or at least, very similar. The Empires and Sunderlands had wingspans of over 110ft. He does claim that the Stirling had to fit in a hangar.

I also have British Secret Projects, by Tony Buttler. He states that the British had hangars 120ft wide, and that the specification required 'good facilities for maintenance in the open'. He claims that the 100ft limit was to keep the aircraft from becoming too large. Buttler recommends reading The Royal Air Force and Aircraft Design 1923-1939, by Colin Sinnott, for a fuller description. Apparently, a lot of Short's records were lost during the war. This may explain the lack of office memos.

Lancasters had single stage supercharger Merlins. Would these have been any better at altitude than the Hercules engines?

 

[33k in the air]

Proof of this can be found with the Lancaster II (Hercules engined) vs. Lancaster I/III (Merlin) - the former struggled at altitudes and suffered in terms of range/payload.

This sort of thing is often stated, but what is lacking is a solid quantifying of such differences. I'm not yet able to add definitive comparative data (I'll be able to offer some once I've gone through 106 Squadron's bomb loads).

I can say the data so far shows the Lancaster II regularly hauled heavier bomb loads to Berlin than did the Halifax III.

 

[nuuumannn]

We can recall that Halifax was an useful bomber when powered by Hercules engines, and was pretty bad with Merlins on board.

That was more of the design of the Halifax rather than the engines themselves. The mounting of the engines on the Halifax's wing created unforeseen drag and there was much correspondence between RR and HP about it, but oddly, changing to the Hercules in the B.III seemed to settle the engine drag issue.

Unfortunately, the reasoning for such a big, draggy & heavy fuselage, (that was also a driver for wing area required, that in return pushed upwards the weight and drag of the wing, too), is seldom mentioned.

I mentioned it earlier. The sheer size of the Stirling and weight creep during its development ensured that it wouldn't have exceptional performance, and as I mentioned, a 100 foot wingspan was for the time very large - the Stirling was a big aeroplane for the time. The restriction was as much insurance against the aircraft becoming too large and unwieldy, as well as keeping take-off and landing distances down to be able to operate from existing airfields. Looking at the comparison diagram and taking the completed Halifax and Lancaster into consideration - their origins being the sister requirement to B.12/36, P.13/36, the specification could have been easily met by a smaller aeroplane.

Operations from existing facilities appears to have been the main focus of the specification - the hangar width, although not specified in the requirement went into the Air Ministry's thinking behind the concept, but as a consideration behind restricting the wingspan, but most authors have picked up on that single aspect of the overall expectation. The fact that Gouge, Short's designer wanted to build an aeroplane with a span of 112 feet certainly lends credence to the suggestion, but again, restricting the span was as much a design (to keep size and weight down) as well as an operational consideration (to be able to operate at existing airfields). As Howard pointed out - good reference, Howard, and a great book, RAF hangars were certainly big enough, but the overall consideration was flexibility and the ability of what was predicted to be a large aeroplane (!) to use existing RAF facilities and airfields, which were, at the time of B.12/36's issue largely grass.

The Hercules VI fitted to the Stirling was supercharged.

 

[Acheron]

So, that the wingspan was restricted due to hangar dimensions is a myth? If so, I can understand why it persists, it is a very plausible story. AFAIK, the Stirling was developed around the time Britain used transport/bomber aircraft for duty in the colonies? If the Stirling was developed with that purpose in mind, then trying to fit it in around hangar spaces worldwide would make sense, given how widespread the Empire was, creating bigger hangars around the globe sounds like a costly undertaking.

But the wingspan was restricted? Why?

All in all, it sounds like the Short Stirling was a rather poor design, even given that it was an early one.

 

[Simon Thomas]

The initial proposal design was fine, however the incessant "improvements" thrust upon Short Brothers slowly strangled it.

For a bomber that was handed over to the RAF in August 1940, it was a significant increase in capability to what was in service then. It is easy to criticize it in comparison to later bombers, but the delay between the start of design and becoming operational was during a time period of rapid improvements in engines and fuel.

I feel that one of its more important impacts was that it taught the Air Ministry to stop micro-managing the manufacturers with ridiculous "requirements" during design. Compare their refusal to allow Shorts to have a 112' span compared to their response to Avro's request to add two more engines to the Manchester.

It is noteworthy that the Stirling stayed in production until November 1945.