Short Stirling Mk.III vs. Piaggio P.108B Bombardiere

Piaggio P.108B Short Stirling

The bomber took prominence in the world’s air forces during the 1930s to the point where an air force’s strength was determined almost solely by how many bombers they could field above anything else. This spurred on bomber development often at the negligence of development of other combat aircraft and this was especially true in the RAF where at several points in the 1930s the fastest aircraft in the inventory actually belonged to Bomber Command. As the 1930s drew on, the limitations of the single and twin engine bombers then in service were becoming obvious while the expectations of what a bomber could do to win a war was growing without a solid basis in reality. Towards the end of the 1930s several aircraft designers the world over began work on developing new more powerful four engine bombers that offered to revolutionise air warfare. The four engine bomber had the potential to carry a heavier load over much greater distances and sufficient defensive armament to give the crew the ability to fight its way to bomb the enemy’s military and economic.

The RAF had used four-engine bombers as far back as 1918 with the extraordinary Handley-Page V/1500 but these aircraft had proven extremely complex to operate. Now the technology had matured making them more practical and one of the first four-engine “heavies” to emerge in the late 1930s was the Shorts S.29 Stirling. The Stirling heralded the start of a new generation of heavy bombers for the RAF that included the famed Avro Lancaster and the Handley-Page Halifax as well as several American designs.

short stirling iii a

Sadly, the Stirling is remembered as being the least successful of the three. Even before the first metal was cut in building the prototype the Stirling was already doomed thanks to pre-war thinking. The Stirling’s altitude performance was curtailed by a limit imposed on the aircraft’s wingspan by the Air Ministry, a decision that was dictated by the need for it to be housed in existing hangars. Another example of this pre-war thinking that would prove problematic for the entire RAF’s combat force was the need for the defensive armament to comprise of .303 (7.7mm) machine guns, the same calibre as the Army’s rifles, in order to ease the burden on the logistical chain. While the logic behind both these decisions is obvious, both caused problems for the Stirling when it came to defending itself against enemy fighter attack (while RAF fighters adopted 20mm cannons, Bomber Command’s aircraft carried on firing .303 rounds until the end of the war).

Despite these shortcomings the Stirling still offered a dramatic increase in performance over existing twin engine “medium” bombers such as the Bristol Blenheim and the Handley-Page Hampden. While it may not have done as much as the Lancaster or Halifax to bring Nazi Germany to its knees the Stirling laid the ground work for its compatriots to follow up with. The Stirling first flew in May 1939, entering service a year later and after a brief combat career as a bomber the aircraft found its niche as a glider towing aircraft. A great many number of the troop- and supply-gliders launched on D-Day were towed by Stirlings and it is this mission which was perhaps its greatest contribution to the war effort.

In Europe the UK seemed to be almost the only nation that had a genuine interest in four engine strategic heavy bombers by the late 1930s with a solid plan in place to develop and build a force of them. Germany, for the time being at least, remained committed to their force of twin-engine “Blitz bombers” such as the Dornier Do.17, Heinkel He.111 and Junkers Ju.88. These were excellent designs of their breed being generally superior to similar British designs but were still limited to primarily supporting the Army having the range and warload to attack tactical targets ahead of the frontlines but were generally unsuited a strategic aerial warfare. The Germans expected war to come in around 1945 by which time they would have their own new four engine strategic bomber designs but Britain and France declaring war in 1939 in response to the invasion of Poland meant that those dreams would never be truly realised.

h3

The Axis powers (Germany, Italy and Japan) did have a handful of four engine aircraft in service but they were never as prominent as the twin engine designs. The most well-known was the Focke-Wulf Fw200 Condor maritime (Right) patrol aircraft which Winston Churchill famously once referred to as the “Scourge of the Atlantic”. However, it would actually be Mussolini’s Italy that would take an early lead in developing a four engine strategic bomber for use against the Allies.

The Piaggio P.108 is little known outside of its home country but there were high hopes placed upon it when it was conceived by Italian aircraft designer Giovanni Casiraghi in the late 1930s. Casiraghi had been inspired by developments in the United States having spent several years working there and seeing the plans for future strategic bombers then in development most notably the Boeing B-17 Flying Fortress. Upon returning home he began work on his own four engine bomber design and designed the Piaggio P.50; a large all-wood monoplane design with four engines mounted on two mounting brackets in a push/pull arrangement. First flying in 1937, the Italian government proved sceptical and no order was placed.

Piaggio P.108B 2Casiraghi returned to the drawing board and adapted the P.50 in to an all-metal design with the four engines spaced out along the wing in an all-tractor arrangement. Initially designated the P.50-II the changes became such that the finalised design was granted its own designation and the P.108 was born in 1938. The Italians weren’t satisfied with having just a bomber however and Casiraghi developed a number of variants for different uses. This resulted in four distinct variants;

  • 108A – Anti-ship variant
  • 108B – Bomber
  • 108C – Airliner
  • 108D – Military transport

In the end only the B and C models were ever built beyond the prototype stage and even then only in small numbers. The aircraft’s combat record was even less impressive than the Stirling’s despite the advantages it offered over other Italian bombers such as the Savoia-Marchetti SM.79 and most of the P.108B bombers ended their days as transports but was it better or worse than the British aircraft?

As with all bomber comparisons this article will look at which aircraft could best carry out the strategic mission. It must be noted that the Stirling was never envisioned as operating in a day bomber role but the P.108B eventually adopted a night role because of the density of Allied fighter opposition during daylight hours.


 

POWERPLANT

Bristol HerculesThe Stirling was powered by four Bristol Hercules II 14-cylinder radial engines each of which produced a respectable 1,375hp. Because of the size of the pistons they were arranged in two rows rather than one row as in smaller engines. It was one of the first radial engines to feature a single-sleeve valve configuration which optimised intake and exhaust gas flow which allowed higher compression ratios. The engine was air-cooled which was advantageous for bomber operations since liquid cooled engines were more susceptible to being damaged by shrapnel but weren’t as powerful as later Merlin engines as fitted to the Lancaster which went some way to explaining the Stirling’s poor altitude performance.

Piaggio P.XIIThe P.108 was one of the few aircraft types of World War II to be powered by engines designed and built by the same company responsible for the airframe. The aircraft was powered by four Piaggio P.XII air-cooled 18-cylinder radial engines that generated an impressive 1,500hp at take-off. The engine achieved this figure by essentially being two French Gnome-Rhône 9K Mistral engines that Paiggio built under license as the P.X (confusingly the Gnome-Rhône 9K Mistral was itself a licensed version of the British Bristol Jupiter).

This coupling of two engines to produce a single more powerful unit reflects the state of Italian aero engine technology in the late 1930s/early 40s which was lacking behind British and German technology. This would ultimately lead to Italy acquiring German engines such as the Daimler-Benz DB 600 series for their fighters. In this instance the forcing together of the two engines in to one unit (which means the P.108 could technically be considered an eight-engine aircraft) resulted in shocking unreliability that resulted in the loss of several aircraft on operations when they were being used to their fullest. In January 1943, serviceability amongst the remaining aircraft dropped to just 2-3 machines forcing their withdrawal from operations.

PERFORMANCE

short stirling iii 3

The Stirling had a maximum range of 2,330 miles depending on the size of the bombload that was carried. Typically, the aircraft flew missions from the UK as far afield as Berlin in East Germany and Northern Italy necessitating a smaller warload (q.v.). The aircraft had a top speed of 282mph and its comparatively high power-to-weight ratio and thick wing made it one of the best handling of all the RAF’s four engine types. A major source of contrition as far as military planning was concerned regarding the Stirling was its low service ceiling especially when carrying a heavy bombload. The aircraft had a maximum (empty bomb bay) altitude of just 16,500ft – 17,000ft thanks in no small part to the relatively thick wings and short wingspan dictated by the pre-war decision to make the aircraft fit in existing hangars. This low service ceiling meant that the aircraft had to fly around the Alps instead of over them unlike the Lancasters and Halifaxes.

Piaggio P.108B 4

The potential the Piaggio P.108B offered the Axis powers was obvious despite the hindrance of the unreliable P.XII engines. The aircraft’s maximum range was only marginally inferior to the Stirling but compared to other common Axis types such as the Savoia-Marchetti SM.79 (1,600 miles) and the German Heinkel He.111 (1,429 miles) it was superior with range being in the region of 2,187 miles. The P.108B had quite an impressive service ceiling, especially when compared to the Stirling, of 27,000ft but where the P.108B suffered was in its top speed. Able to reach 260mph at 14,500ft (depending on bombload) it was considerably slower than the B-17 Flying Fortress, Stirling, Avro Lancaster and Handley-Page Halifax which increased the time over enemy territory and the chances of being intercepted.

BOMBLOAD

A bomber’s capabilities in the Second World War was judged primarily by how many bombs could be carried and how far. The Stirling had a 14,000lb maximum theoretical bombload although this was rarely achieved since it imposed such hefty penalties on the aircraft’s performance particularly with regards to range that a more modest load of around 4,000lbs was the norm. This was similar to earlier twin engine types such as the Vickers Wellington but the Stirling could carry them further and faster. The bomb bay was also unsuitable for carrying some of the bigger weapons the RAF began fielding later in the war.

A typical bombload for the P.108B was higher being in the 7,000lb figure although generally the weapons used were smaller than the Stirling’s 500lb weapons. This did have a knock-on effect with range and when on the longest ranged missions (2,000 miles) a bombload of around 4,000lbs was carried.

DEFENSIVE ARMAMENT

short stirling iii 4The Stirling featured three defensive weapon stations in a typical British arrangement for a night bomber. A powered nose turret featured two Browning .303 (7.7mm) machine guns while a tail turret featured four; this demonstrated the importance of rear hemisphere protection when facing night fighters. The night fighters the aircraft was expected to face such as the Messerschmitt Bf110 and Junkers Ju88 used primitive radar and infra-red equipment to peer through the night after being guided to the aircraft’s vicinity by ground control radar stations. Given the narrow viewpoint this equipment offered they were almost always guided in to a tail-chase position where it would be easier to detect the bomber because of the lower overtake speeds giving the radar operator more time to set up an attack. The Stirling also featured a dorsal turret with another pair of two .303 machine guns which were usually operated in conjunction with the tail turret to attack night fighters in the upper-rear hemisphere.

Piaggio P.108B 3The Piaggio P.108B featured six separate defensive weapon stations. A powered nose turret featured a 12.7mm Breda machine gun while a second 12.7mm gun was mounted in ventral retractable turret for defending against attack from below. There were two waist gunner positions covering both flanks each equipped with a single 7.7mm machine gun. The aircraft lacked a dedicated tail turret but Casiraghi circumvented this with two unique radio controlled turrets equipped with two 12.7mm machine gun positioned on the outer engine nacelles. Theoretically, these provided excellent protection against fighters attacking from the rear hemisphere trying to hit the engines. In practice however they suffered chronic reliability problems, were difficult to aim and affected airflow.

CONCLUSION

Both these aircraft have their strengths over the other but overall the Piaggio P.108B was generally superior or at least equal to the Stirling in terms of performance with the notable exception of it being marginally slower. It has to be remembered however that the Stirling did generate higher sortie rates than the Piaggio design as a result of the P.XII engines which proved to be the Italian bomber’s Achilles-heel.

Piaggio P.108B 2a

Comparing the two aircraft’s ability to defend themselves is somewhat problematic since the P.108B was expected to operate in daylight hours as well as the night while the Stirling was intended to operate exclusively as a night bomber. The P.108B therefore was designed with a greater field of fire with which to fend off enemy fighters although it’s hitting power remained relatively light especially in the rear and forward quadrants when compared to the Stirling which although it had lighter calibre weapons, had a greater concentration of them. The Stirling’s dorsal turret meant it had better protection against attack from above but the P.108B’s ventral turret gave it better coverage from below. The P.108B’s interesting nacelle turrets could have caught more than one unsuspecting Allied pilot out had they worked as promised.

(Images sourced from Wings Pallet & Commons.Wikimedia)

 

 

 

 

 

 

Advertisements

Royal Air Force Memorial Flight Official Club Autumn Journal 2015

Royal Air Force Memorial Flight Club Autumn Journal 2015 ii

The Royal Air Force Memorial Flight Club have published their Autumn Journal 2015. The beautifully produced publication aims to highlight the achievements and exploits of the famous Battle of Britain Memorial Flight and their inventory of historic World War II aircraft including one of only two Avro Lancaster bombers that remain airworthy anywhere in the world. The Royal Air Force Memorial Flight Club aims to support the Flight through raising awareness and funds to keep these historic aircraft in the air where they can best represent those brave men and women who built, flew and maintained them during the darkest days of World War II and beyond.

The Autumn Journal opens with a segment covering the standing down of Squadron Leader Dunc Mason as Officer Commanding of the Flight and the arrival of Squadron Leader Andy “Milli” Millikin as his successor. The Journal then goes in to a range of articles covering the story of the aircraft types the Flight operate. There is a fascinating article on the use of Hawker Hurricanes as night fighters and pays tribute to the Castle Bromwich factory where all four of the Flight’s Supermarine Spitfires were built.

The magazine is lavishly illustrated with beautiful and detailed photographs of the Flight in action during the recent air show season. There is also a detailed photo essay on the newest addition to the fleet, Spitfire LF.XVIe TE311, covering its story from restoration to flight.

This is an intimate look at the Battle of Britain Memorial Flight produced in high quality with the commitment one could expect from the supporters of one of the most public aspects of the Royal Air Force. If you would like to join the Royal Air Force Memorial Flight Club and receive your own copy of the Autumn Journal, then please visit the club’s page at www.memorialflightclub.com.

It costs just £25 (+ postage) to join and profits from the Club help to support the work the Battle of Britain Memorial Flight does. Thanks to Amy Sell at the Club for sending me this copy.

Do you have an event or charity you would like to promote on Defence of the Realm? If so then feel free to email the details to defencerealmyt@gmail.com. 

NEWS: New CO for Battle of Britain Memorial Flight

Sqrn Ldr Dunc Mason (left) and Sqrn Ldr Andy ‘Milli’ Millikin (BBMF Club)

Sqrn Ldr Dunc Mason (left) and Sqrn Ldr Andy ‘Milli’ Millikin (BBMF Club)

After serving for no less than 7 years with the Battle of Britain Memorial Flight, 3 of which have been as commanding officer, Squadron Leader Dunc Mason will be formally standing down from the position on Sunday 25th October. Succeeding him in the post will be Squadron Leader Andy ‘Milli’ Millikin whom has served with the flight for four years learning all he needs to know about the running of the prestigious unit in what has to be one of the most unique jobs in military aviation.

Millikin will lead the flight of historic World War II aircraft through the 2016-2018 display seasons which will now thankfully include the flight’s repaired Lancaster known lovingly as “Thumper”. Earlier this year the aircraft suffered an in-flight fire but fortunately no one was hurt and the aircraft has now returned to the air. Other aircraft in the flight include Supermarine Spitfire and the Hawker Hurricane fighters.

Squadron Leader Mason will be leaving the job to Millikin in order to take up the post of Officer Commanding Advanced Squadron, Central Flying School Examining Wing. This post will see him become responsible for examining all aspects of advanced flying and flying training for the RAF ensuring that the highest of standards are maintained.

To keep up to date with the latest developments involving the BBMF you can join the flight’s official club.

NEWS: Battle of Britain Memorial Flight Lancaster returns to the air

"Thumper" in flight (commons.wikimedia)

“Thumper” in flight (commons.wikimedia)

The Battle of Britain Memorial Flight’s (BBMF) Avro Lancaster  B.I PA474 (nicknamed Thumper) has returned to the air for the first time since an in-flight fire earlier this year grounded the aircraft while repairs were carried out. It had been due to take part in a number of flypasts throughout the summer including overflights of Buckingham Palace accompanied by Hawker Hurricanes, Supermarine Spitfires and Eurofighter Typhoon FGR.4s. Since the fire the aircraft has undergone extensive repairs with many parts having to be specially made while an exhaustive check of all the aircraft’s components has been undertaken to ensure none were damaged in the fire.

7,377 Avro Lancasters were built between 1941 and 1946 but only two aircraft remain airworthy in the world. The other aircraft resides in Canada but last year the two aircraft met in the skies of the UK for a dramatic airshow tour that many hope we will see again one day. The engineers at RAF Coningsby where the aircraft is based deserve to be applauded for their tireless efforts to keep this incredible aircraft in the air.

NEWS: Last pilot of the Dambusters dies aged 96

Les Munro

Squadron Leader John Leslie Munro, CNZM, DSO, QSO, DFC, JP (5 April 1919 – 4 August 2015)

The last surviving Dambusters pilot, Squadron Leader Les Munro, has died at the age of 96. Munro died in hospital in his native New Zealand on Monday following heart problems, the New Zealand Bomber Command Association has said.

There are now only two surviving crew members of the Dambusters missions. Out of 133 crew who went on the mission only 77 returned and Squadron Leader Munro’s own aircraft was hit by flak over the German occupied Netherlands which left it without communications for the remainder of the flight.

Dave Homewood, of the New Zealand Bomber Command Association, described Munro as a “down-to-earth man” who was “very modest about what he did during the war”. Just recently he had auctioned some of his medals to help raise £500,000 for an airman’s memorial in London.

As my own personal little tribute to Squadron Leader Munro the above photo will be made the cover image for Defence of the Realm’s Facebook page for 24 hours. He will be remembered.

– Tony

NEWS; BBMF Lancaster suffers in-flight engine fire

Lancaster fire

SOURCE: Karl Melson via BBC

The Battle of Britain Memorial Flight (BBMF) Lancaster, known affectionately as Thumper, has had to perform an emergency landing at RAF Coningsby after after suffering a mid-air engine fire during a training flight. None of the crew were hurt in the incident and the fire was suppressed before it could cause any major damage to the airframe. The fire appears to have begun after the engine misfired in-flight.

The aircraft is the only airworthy example of the Avro Lancaster bomber in the UK. The only other example is located in Canada and last year the two aircraft met and flew together, the first time more than one Lancaster had been in the air at the same time in over 40 years. That aircraft suffered a similar incident last year but is flying again.

Lancaster – Short Film

A beautiful and powerful short movie chronicling the crew of a Lancaster bomber during the critical moments of the mission – the bomb run. The short film ends with a touching interview with a veteran of Bomber Command who gives his own personal thoughts on going to war in an Avro Lancaster.