“Fatal” meaning “deadly.” I was friends with the late Jeffrey Quill, the top Spitfire test pilot through most of its development who flew and fine-tuned all 52 variants and while he acknowledged many of the Spitfires “shortcomings”…
…her vulnerability and even frailty, complexity and expense, terrible landing gear, horrible fuel capacity, initially under-gunned and its on-going altitude issues, he saw most of these factors as “trade-offs” R.J. Mitchell made as there are always trade-offs in any design, and I in general agree.
But *many* Spitfire pilots did die in her because of these and other “issues.”
Here’s a few:
There were 52 (!) different Marks of Spitfire. It was constantly in development from 1936 till 1949, and it grew from 1,030 to an incredible 2,375 HP with the Griffon-powered versions, from 362 to 439 mph, and reach altitudes from 32,000 to 43,000 feet, so any discussion of its “weaknesses” has to be a bit broad, as much of the directions the Spitfire went by R. J. Mitchell were conscious and deliberate choices but…
Yes, there were flaws in the design and Spitfire pilots died because of them, so here’s a few…
1. The liquid-cooled Merlin’s cooling system, esp. with double radiators in the bottom of its wings, its after cooler system and oil/oil cooler system were all very vulnerable to enemy fire, esp. from behind and below, one of the #1 reasons for Spitfire loses.
2. Its Rolls Royce Merlin was a bit busy and took more maintenance man-hours than similar inline V—12s. It was significantly harder to work on, maintenance-wise for the crews, as its parts were buried deep inside the tiny fighter, making it difficult to reach-lots of wasted taking-off and putting-back-on time. The tight tolerances of the Merlin made it a poor carrier-based engine that needed total replacements every 200 hours from the over-revving and vibration/pounding of carrier landings, entirely different than the huge, brutal, reliable-as-an-anvil, loose-tolerances of the American-made air-cooled Pratt & Whitneys.
3. It was very small and lightly built, and simply couldn’t take the pounding of German 20–30mm HE MINE cannon hits. As a Seafire, carrier based aircraft, it was too small and lightly built and couldn’t take the slamming of carrier operations. It needed significantly more maintenance than comparable American Hellcats, Wildcats or Corsairs. Another top reason for Spitfire losses.
4. It was complicated, slow and expensive to build, esp, the elliptical wing. A single Spitfire Mark V took 13,000 man hours to build and at the height of wartime production, Spitfires were being built at 6 every day. A Bf 109G took 4,000 hours to build and a significantly more intricate and complicated P-47 with electric dive flaps, electric gauges, and a turbo-supercharged engine took 9,100 hours.
5. Its beautiful elliptical wing didn’t always allow significant internal fuel and ammo for its cannons or the ability to externally carry significant ordnance/drop tanks.
6. Its terribly narrow landing gear “geometry” caused many crashes on taxiing, take offs and esp landings on grass fields or carriers and the Seafires were particularly hard hit killing/injuring many aviators.
7. It had early carb starvation problems in negative G dives, unfortunately during the crucial Battle of Britain, a few pilots died because of this flaw.
8. Early models were under gunned, and lacked suffiencent ammo for the 20mm Hispano’s.
9. It had terrible range from low internal fuel storage and because of its small/slight build, could not carry adequate external fuel/drop tanks, limiting it to air-to-air and taking away bomber escort and ground attack roles. (The ground attack role was also compromised by #1 above, as like most liquid-cooled fighters, couldn’t take the pounding of anti-aircraft cannons.) Some question the fuel tank placement just in front of the pilot ala F4U, but this wasn’t a huge concern, as it turns out, many aircraft choosing to place the tank *under* the pilot.
10. It was never a great high altitude fighter, limited to most of its Marks to under 37,000 feet where the Bf 109 G could perform at 39,000 feet, P-51 could perform at 42,000 and the P-47 at 43,000 feet.
11. A very good Diver, and its frame could take a stress from a dive…but only so far and would then instantly and un-expectantly break apart, affecting the pilot’s confidence in the really fast dives. But it was mostly a good “vertical-plane fighter” but early Spitfires had difficulty with control in the dive, which was largely solved on later variants by replacing the fabric covered control surfaces with all metal ones, but it took a year, July ’41 beef it happened. Early Spits also suffered from wing fatigue, limiting their dive mach number. Early-mid Spits were limited in the dive for other reasons, including the rev limit on the Merlin was 3000 rpm, as over 3000 would severely shorten its life. 3,150 was permitted but for only 20 seconds, so underdeveloped prop pitch control and range limited their diving speeds till the mid-Marks, but the Spitfire V had a major dive problem develop around 1942 caused by weight and Center of Gravity shift that was eventually solved via bob weights. But once the bugs had been sorted out, she was a good “Boom and Zoomer”
12. As for the Roll it performed well, equal or better through most of its life to the Bf 109 but far poorer than the fabulous Fw190. There were problems but over time changes were made, wings were clipped, and NACA 868 reports shows a Spitfire roll rate peaking at 200 mph, at 150°/sec for a clipped wing version and 105°/sec for full wing version. But again, there were corrections to the ailerons throughout the war. Some spitfires were modified by changing the wings from the original elliptical shape to a “clipped” planform that ended abruptly at a somewhat shorter span. This sacrificed some turning performance, but it made the wings much stiffer and therefore improved roll rate.
It was a tremendous aircraft, one of my favourites, (and to my artist’s eye, likely the most beautiful of all WWII aircraft), but it had a number of “weaknesses,” I suppose, most connected to her small size and light build and affected her versatility.
The Spitfire was very fast, quick, agile, manoeuvrable, with a good (but not great) rate of climb. To achieve that it had to be, by design, light, small, narrow/aerodynamic, very slightly built, with a thin wing, and a bit fragile, perhaps, compared to other stronger fighters. It was also difficult and expensive to build: costing roughly $63,000 US when a P-51 was $51,000.
So to take on those 11 issues:
1. The liquid-cooled Merlin’s cooling system, esp. with double radiators in the bottom of its wings, its after cooler system and oil/oil cooler system were all very vulnerable to enemy fire, esp. from behind and below.
One of the problems with the Spitfire’s vulnerabilities is it’s liquid-cooled Rolls Royce Merlin V-1650 inline engine.
(Above: Spitfire’s coolant system which took up about 1/3rd of the aircraft: two radiators, coolant hoses and fittings, water pump, coolant/header tank, were all totally unarmored, and just like your family car, one tiny piece of high velocity metal as small as a fingernail clipping, could piece the coolant system and within a few minutes the coolant ouldbe expelled under pressure of the water pump, the tight-toleranced, liquid-cooled engine was now an air-cooled engine, the engine would overheat, pieces would expand and seize and your Spitfire was now a brick.)
(Above: Showing the vulnerability of both sister aircraft, liquid-coolant radiators…on the bottom of the aircraft, THE most vulnerable place from fire from behind and below.)
(Above: It had two radiators in the wings, and top Grumman test pilot “Corky” Meyer wrote: “It’s highly visible engine oil and coolant systems under the wings were very vulnerable to aerial and ground attacks.”)
Here’s what the P-51 designer Ed Schmued said about the vulnerability of his own Merlin-powered P-51, that applies equally to the Spitfire:
“335 F-51D Mustangs were lost in the Korean War, with 264 pilots killed or missing. Of these losses, 172 fell to enemy ground fire, ten to enemy jet fighters, with forty-four missing and unaccounted for, and the remainder to accidents. “Unfortunately, the P-51 was a high-altitude fighter. [In Korea] it was used in ground support work, which is absolutely hopeless, because a .30-caliber bullet can rip a hole in the radiator and you fly two more minutes before your engine freezes up. Flying a P-51 in ground support was almost a suicide mission. It is unfortunate that the airplane had been used for ground support, but in the Korean conflict we were short of airplanes and anything had to do. This was the reason for using the P-51 in low-level operations.”-Ed Schmued, P-51 designer,”-MUSTANG IN KOREA-Weapons and warfare.
MUSTANG IN KOREA
Lt A.E. Helseth, a young American U.S. Air Force pilot with barely 200 hours of Mustang flight time in his logbook, was flying in a section of Republic of Korea Air Force F-51s led by Major Dean He…
And here’s what “Corky” Meyer, Grumman’s top test pilot in WWII/Korea and America’s top civilian test pilot of all time said on evaluating the P-51s (B/D/H) he tested:
“…Its other far worse vice was its vulnerability when shot at from the rear. The engine-cooling radiator was located in the belly of the aft fuselage and was an easy target, which could be quickly fatal to the engine’s combat life. Note: The air-cooled radials of the P-47s, Hellcats, and all of the other of the radial-engined powered aircraft had no liquid coolant engine-stopping vulnerability and their oil coolers were usually buried safely behind the engine. Many unfortunate P-51 and P-38 pilots had to bail out over enemy territory because of this drawback and spent the rest of the war In very inhospitable German stalags (prisons.) The P-51D had the greatest model production run of 7,956 aircraft. Its major vulnerability to enemy ground and aerial gunfire was from its oil and engine coolant radiators located in the aft fuselage.”-’”Corky” Meyer’s Flight Journal: A Test Pilot’s Tales of Dodging Disasters-Just In Time.’ Pages 159–160, 2006, Specialty Press.
(Above: Very similar to the P-51, the Spitfire’s coolant and after coolant systems and radiators and incredibly vulnerable to rear and lower fire. This was one of the main reasons for Spitfire losses in the war.)
A real Spitfire weakness is the vulnerability of the twin radiators being hit from the rear/beneath. So many P-51s were destroyed this way that when the new P-51H was developed, the oil cooler was moved from inside the belly scoop to in front of the oil tank ahead of the firewall, deep within the aircraft. This also eliminated the vulnerable oil lines that ran from the engine to the old location in the scoop. The oil was now cooled by a heat exhanger mounted next to the engine intercooler. Unfortunately when the P-51s were sent o Korea, they sent the old D models with the vulnerable radiator scoops in the belly and the H’s never saw combat. The Mustangs then took heavy losses in Korea from ground attack that Ed Schmued so regretted.)
2. Its Rolls Royce Merlin was a bit busy and took more maintenance man-hours than similar liquid-cooled inline V-12s.
The Allison V-1710 V-12, for instance, had aprox. 7,000 parts vs the Merlin’s aprox. 11,000 parts, and both made pretty comparable HP, although the number of *moving* parts are more equal.
In the USAAF Statistical Digest…
USAF STATISTICS SINCE 1945 While the USAF Statistical Digests and Summaries are not AF History publications, the information they contain is valuable and often requested by researchers. The statistical data has been collected, compiled and produced since 1945 by the Comptroller of the Air Force. Earlier Digests contained a wealth of information about the USAF. Some include organization charts, leadership lists, lineage of commands, installation maps, chronologies, etc. Be aware that categories of statistics may change, as well as the starting date of the fiscal years. Categories may be dropped, added, combined with others and may vary in methods of calculation throughout the years. Many of the electronic files were produced by manually cutting apart and scanning existing documents. Quality varies. AF Historical Support Division does not have a Digest/Summary for all years. 2013 is the last year that the Statistical Digest was published.
…the numbers showed that the average man-hours expended per major engine overhauls in continental US-based maintenance depots from July 1943 through August 1945 on a monthly basis, showed the Packard Merlin V-1650 required an average of 320.2 man-hours per overhaul with a high of 592 hours and a low of 190hours.
And During the same period the Allison V-1710 required an average of 191.5 man-hours per overhaul with a high of 376 hours and a low of 117 hours.
(Above: A factory worker makes the final adjustments to the Supercharger, which is now ready to be fitted to the engine at this factory.)
The Merlins used on the Seafires were battered and overworked in the initial extra boost/revs need to help get airborne and the continued pounding of all carrier operations. The Merlin wore out quickly by over revving and 3000 rpm was the red line with 3150 allowed for only 20 seconds. The Seafire engines needed complete, 100% replacing after only 200 flying hours. The Merlin, jewel of an engine that it was, (and I’ve seen that personally having had the chance to personally get my hands greasy on a Merlin out of a P-40F work, and involved with the restorations/installations of two additional P-51s and their Packard Merlins,) but I also had the chance to help maintain a P&W R-2800 in a friends F4U that, while not such a pretty jewel, seemed infinitely tougher and hardier.
3. It was very small and lightly built, and simply couldn’t take the pounding of German 20–30mm HE MINE cannon hits.
(Above: It was seven feet shorter than a P-47, and empty weight of 5000 lbs was almost half that of the 10,000 lb P-47, and its gross weight of 6600 abs compared to the P-47 at 17,500 lbs. BIG is GOOD! BIG means redundancy of vital systems, steel, steel and more steel to stop German cannon shells, and the strength to taking any kind of pounding, not have your wings tear away I dives, and the strength to carry a decent payload r external fuel.)
And another trade-off to this design, and there are always trade-offs, was that it simply could not stand 20–30mm cannon hits from the German guns, it was too small and weak to carry a lot of internal or external fuel, 20mm ammo and a decent bomb load.
German thin-skinned 20mm and 30mm cannon shells with “MINE” capabilities, i.e. very high explosive, could rip open Allied aircraft like a can opener:
(Above: Modern 20mm HE shell vs .50 caliber, but you get the idea…)
(Above: Some Allied and esp. German ammunition.)
A1: U.S. .50 cal BMG (12.7 MM) and .30 cal (7.62 mm) Light Machine Gun Rounds, (Not too dissimilar to the British .303.)
The Germans relied on these caliber cannons/shells:
E: 20mm from the Oerlikon MG FF.
F: 20mm Mauser from the MG151/20 – The excellent replacement to the MG FF and became the primary aircraft weapon for the Luftwaffe from about 1942 to 1944,
G: 30mm from the Mk 108- Although having a lower ballistic performance so it was like tossing softballs, the gun was relatively light and compact. Fighters could carry two or in the case of the Me 262, even four MK 108s.
(Above: 30mm Mk 108. Short barrelled, low velocity but very hard hitting.)
You get hit by an “F” or a “G” and you don’t have “problems,” you’ve got “Trouble.” Be afraid, be very afraid. P-47s, and dual/multi-engined craft like Mosquitos, P-38s and bombers could take a couple of hits and still get home…not a Spitfire.
Please watch these two very brief clips of tests the RAF did firing a German Mk 108 30mm with HE Mine-Geschoss shells against a Spitfire to prove my point. Holy SH*T!!!:
(Above/below: RAF Test of the Rheinmetall‑Borsig MK 108 30 mm destructive power [Colorized] vs a Spitfire.)
(Above: Art Sager and his damaged Spit. Hurricanes, Spits, Bf 109s and P-51s could shake off machine-gun bullets but cannon fire wasn’t so easy…)
The Spitfire is very slender, of very light build and relatively fragile, although its stressed-skin structure was a huge step up from the Hurricane’s. But one good cannon hit and its “Adios muchachos.” )
(Above: A single German 30mm HE shell hit this P-47′s wing. Steel, steel and more steel. She made it home. Go back and watch the same 30mm shell test blowing the wing and then the tail right off the Spitfire.)
(Above: Likely a German 30mm HE shell hit this P-51D’s tail.)
(Above/below: Some early-war German 20mm cannon hits. The German HE shells were to get far more destructive as the war progressed.)
4. It was complicated and expensive to build, esp, the elliptical wing, AND…
5. Its beautiful elliptical wing didn’t always allow significant internal fuel and ammo for its cannons or the ability to externally carry significant ordnance.
8. Early models were under gunned, and lacked sufficient ammo for their 20mm Hispano’s.
All at once…
(Above and images below: A quick, fun gallery of Spitfire manufacture. Castle Bromwich factory, Birmingham. Spitfires were expensive, difficult and slow to manufacture. Tommy Shelby and Aunt Polly (RIP) are working on a scheme in the back office.)
(Above/below: same photo of Birmingham factory, one colorised for comparison.)
(Above/Below: Perhaps I’m just a jaded, mechanised American, but doesn’t some of these images of Spitfire manufacture look a little…disorganised? Like a “Chinese Fire Drill?”
(Above/Below: For comparison: P-51 Mustang manufacturing line. One was made every two hours. Corelli Barnett, in Audit of War, famously wrote a Mark V Spitfire took 13,000 man-hours to build, and at the height of wartime production, Spitfires were being built at 6 every day, 186 in a month. The North American plant in Inglewood, Ca, once churned out 571 P-51s in a month. I go into this in detail here:
How long did it take to build the P-51 Mustang fighter?
A Bf 109G took 4,000 hours to build, a double-boomed P-38 took 9,600 hours, a B-25 bomber took 10,700 hours and a significantly more complicated P-47 with electric dive flaps, electric gauges, and a turbo-supercharged engine took 9,100 hours.
(Above: Spitfire pilot “flat-hatting.” Guess who’s grounded tomorrow?)
Let’s all about that big, beautiful but thin and complicated Spitfire elliptical wing. When you think “Spitfire” you think of two things, a Rolls Royce Merlin and that elliptical wing that R.J. Mitchell put everything he had learned working on the high speed Schneider trophy-winning aircraft into the Spit.
(It’s elliptical wing was so complicated and expensive that basically only a few aircraft in WWII had others, including: The He 111, the Japanese “Val,” the Italian Reggiane 2000, the Hawker Tempest and the P-47 Thunderbolt. The P-47, though huge and seemingly lacking slippery aerodynamics, actually had an incredibly efficient drag coefficient of .0217, second only to the P-51D’s and P-63A Kingcobra’s .0176.)
The reasoning for the elliptical wing was simple: the design called for a shape which needed to be thin to avoid creating too much drag, but it had to be thick enough to house the retractable undercarriage, armament, and ammunition. It was decided that an elliptical planform was the most efficient aerodynamic shape for an untwisted wing, leading to the lowest amount of induced drag.
This wing shape was, however, difficult to manufacture. By the end of the war, engineers had come up with several wing planforms that were nearly as efficient as the elliptical wing, but were much easier to manufacture.
Being so complicated and comprising so many individual parts, Spitfire wings took up a major portion of the time and expense the Spitfire’s manufacture. Definitely a problem.
Some spitfires were modified by changing the wings from the original elliptical shape to a “clipped” planform that ended abruptly at a somewhat shorter span. This sacrificed some turning performance, but it made the wings much stiffer and therefore improved roll rate.
The Merlin-powered Spitfires used four different wing types, A through to D which had the same dimensions and plan but different internal arrangements of armament and fuel tanks. After introducing the Griffon, Supermarine recognized the need for a completely revised laminar-flow wing to facilitate even higher speeds made possible by this powerful engine. Starting with production Spitfire Mk 21, this wing became standard for post-war variants of this famous fighter.
(Above: Part for why the Spitfire was so expensive/difficult to built: the complicated wing spars.)
The majority of the day fighter Spitfires from the Mk I through Mk XVIII used four basic wing types, A, B, C and E, but for “a “weakness,” I’ll just look at the early A and B types that didn’t allow enough firepower…
The original wing design, the basic structure of which was unchanged until the arrival of C type wing in 1942. The only armament able to be carried was eight .303-calibre Browning machine guns with 300 rounds per gun.
Each .303 was roughly 1/2 the fire power of a Browning M2 .50 caliber, so it had the equivalent of four .50s. As discovered with the first American P-51Bs with only four .50s, just not enough firepower.
Towards the end of 1940 the fabric covered ailerons were replaced by ones covered in light-alloy.
(Above: General arrangement of the Type A wing. You can see the outlines of the eight .303s, each with only 300 rds per gun, that frankly were not enough firepower, serious weakness in the early Spitfires.)
This was the A type wing modified to now carry 20mm Hispano cannons. One type of armament could be fitted, comprising two 20 mm-calibre Hispano Mk II cannon, fed from drum magazines with the capacity of 60 rounds/gun, and four .303 Browning machine guns with 350 rounds per gun.
Each 20mm Hispano had roughly the firepower of three Browning M2 .50s, so this was the equivalent of eight .50s, but the 20mm ammo was very low with only 6 seconds of fire, total.
The alloy covered ailerons were standardised on this wing type.
(Above: General arrangement of the Type B wing. You can see the outlines of the four .303s, each with 350 rds per gun, and the two 20mm Hispano’s, now very decent firepower, but again, only 6 seconds of shooting for the 20mm.)
6. Its terribly narrow landing gear “geometry” caused many crashes on taxiing, take offs and esp landings, and the Seafires were particularly hard hit.
Another weakness of the Spitfire, and a big one was her very narrow landing gear. Not as terrible as the criminally insane “geometry” of the Bf 109 that caused thousands of taxiing, take-off and esp..landing accidents that killed or injured thousands of young pilots, mostly in the last year of the war with the very green German pilots with little experience and training dealing with the chronic problems of the 109s fragile and poorly designed landing gear, all to keep Willy Messerschmidt’s (admittedly) beautiful wing. Tragic and stupid.
(Below: The Spitfire was similar in design but not quite so narrow, and with its tires firmer and more directly placed on the landing surface, gave it an edge:)
(Below: As the war was in it its final year and German fighter pilot training fell off to almost nothing because of fuel and teacher shortages, thousands of green pilots in hopped-up Bf 109Gs and Ks crashed and often died esp. on landings. The Bf 109 had always been twitchy and you learned to land with your foot always touching the left pedal and ready to counter act a ground loop. There were possibly as many as 11,000 take-off, taxiing and esp. landing accidents in the Bf 109s almost decade of service. Willy Messerschmitt knew of the flaw and was desperately confronted by his design team but chose not to fix it, to keep his incredible wing, condemning thousands of 109s to crash and thousands of German boys to death or injury. Here’s the even more fatally narrow/poor Bf 109’s gear with the tires on their edges:)
(Below: Now here’s the brilliant Fw 190 gear, similar to the P-51 and P-47, with tires firming on the ground:)
“Corky” Meyer was sent to London immediately after V-E Day to extensively interview Focke Wulf designer, Kurt Tank. They were both outstanding test pilots and got along well. “Corky” said Tank didn’t necessarily have a lot of admiration for Willy Messerschmidt, and specifically berated him for the criminally insane “geometry” of the Bf 109’s horribly narrow landing gear that lead to over 10,000 take-off, taxiing and mostly landing crashes during its decade-long service, esp. the last year with green boys, untrained/unaccustomed to the Bf 109’s “eccentricities” and penchant for ground looping at the best of times, made even worse with the new hot-rodded G and K versions, known for torque surges on landing.)
Top Spitfire test pilot Jeffrey Quill spoke to me about the Spitfire’s tough landing gear, esp. in the Seafire version on unforgiving carrier decks and the work he and Capt. Eric Browns did on the Seafire’s gear. A successful Seafire deck landing/capture needed a “three-point” landing. If the fighter hit the deck on just its main wheels, it would bounce over the arrester wires and go into the crash barrier.
(Above: Seafire crash landing aboard escort carrier HMS Stalker. Seafires were terrible carrier aircraft for 1000 reasons.)
Ongoing attempts were made to mitigate its landing weaknesses: In March 1943 all Seafire Mk IB and IIC aircraft received modifications to their arrester hook to increase its load from 7000lbs to 10,500lbs. In August that year the strengthening of the arrester “A” frame and fittings was initiated.
(Above: Seafire crash. I believe you can see under the tail on the left a severed landing gear almost taking out a deck crewman.)
A major discovery of these trials was that arrester wires needed to be correctly tensioned to avoid the tail of the Seafire rising after capture, which – in turn – caused the propeller to make contact with the deck.
“As regards the speed of the (early) Seafire, the added weight of strengthening the fuselage to take the heavy arrester hook had reduced this quite considerably and indeed it was far from being the famous fast Spitfire from which it was derived. — FAA pilot, Henry “Hank” Adlam: The Disastrous Fall and `Triumphant Rise of the Fleet Air Arm from 1912 to 1945
The Seafires were notoriously hard to land on a heaving deck, esp. with the very poor and narrow landing gear. The Royal Fleet Air arm had terrible losses till they could be sorted out and their aviators taught better landing technics, mostly taught by top Spitfire test pilot, Jeffrey Quill. 1,620 Seafires were built but it was a poor carrier aircraft, in many respects similar to the F4U Corsair, in destroying more aircraft in operations losses and killing more aviators than in combat by a wide margin. The Seafire had the same problem as other Spitfires as because of its low internal fuel storage, it had a vey short operation range for CAP.)
(Above: French Seafire crash on the carrier L’Arromanches. To quote the pencil written note on the back side of the photo “Aircraft ended its course in the net and as usual pilot escaped uninjured”. Photo taken by my grandfather during a mission to Indochina. – Photo taken at Sea [OFF AIRPORT] in International Airspace in 1948.”)
Three aircraft and the escort carrier HMS Ravager were allocated to an urgent program of testing in an effort to identify problems and develop improved landing techniques. In November 1943, test pilot Lieutenant Eric Brown found himself behind the stick of a Seafire.
(Above: A Supermarine Seafire hits the barrier on HMS INDEFATIGABLE after returning from a strike on the Japanese oil refinery at Pangkalan Brandan, Sumatra.)
His orders: Put the Seafires through a rigorous program of testing “until something broke”.
This he did: He wrote-off two of the machines. His testing program involved landing at incrementally lower speeds and heights, as well as experimenting with different approach techniques.
The main undercarriage legs were strengthened and extensive landing trials conducted aboard HMS Pretoria Castile in February 1944 and HMS Indefatigable in March to find ways to eliminate Seafire’s tendency for arrester-hook bounce.
A major discovery of these trials was that arrester wires needed to be correctly tensioned to avoid the tail of the Seafire rising after capture, which – in turn – caused the propeller to make contact with the deck.
Combined with improved training, this fleet carrier’s Seafire attrition rate fell to acceptable levels.
7. It had early carb starvation problems in negative G dives.
One of the Merlin’s drawbacks however, was its carburetted air-fuel delivery. It was calculated that the lower temperature in the carburettor would provide a denser air and fuel mixture and therefore more power over a fuel injected system, but this came a cost of continuous fuel supply. If a Merlin powered aircraft nosed down into a steep dive, the Negative G force…
g-force – Wikipedia
Term for accelerations felt as weight and measurable by accelerometers This article is about effects of long acceleration. For transient acceleration, see Shock (mechanics) . In straight and level flight, lift ( L ) equals weight ( W ). In a steady level banked turn of 60°, lift equals double the weight ( L = 2 W ). The pilot experiences 2 g and a doubled weight. The steeper the bank, the greater the g-forces. This top-fuel dragster can accelerate from zero to 160 kilometres per hour (99 mph) in 0.86 seconds. This is a horizontal acceleration of 5.3 g. Combining this with the vertical g-force in the stationary case using the Pythagorean theorem yields a g-force of 5.4 g. The gravitational force equivalent , or, more commonly, g-force , is a measurement of the type of force per unit mass – typically acceleration – that causes a perception of weight , with a g-force of 1 g (not gram in mass measurement) equal to the conventional value of gravitational acceleration on Earth, g , of about 9.8 m/s 2 .  Since g-forces indirectly produce weight, any g-force can be described as a “weight per unit mass” (see the synonym specific weight ). When the g-force is produced by the surface of one object being pushed by the surface of another object, the reaction force to this push produces an equal and opposite weight for every unit of an object’s [ which? ] mass. The types of forces involved are transmitted through objects by interior mechanical stresses. Gravitational acceleration (except certain electromagnetic force influences) is the cause of an object’s acceleration in relation to free fall .   The g-force experienced by an object is due to the vector sum of all non-gravitational and non-electromagnetic forces acting on an object’s freedom to move. In practice, as noted, these are surface-contact forces between objects. Such forces cause stresses and strains on objects, since they must be transmitted from an object surface. Because of these strains, large g-forces may be destructive. Gravity acting alone does not produce a g-force, even though g-forces are expressed in multiples of the free-fall acceleration of standard gravity. Thus, the standard gravitational force at the Earth’s surface produces g-force only indirectly, as a result of resistance to it by mechanical forces. It is these mechanical forces that actually produce the g-force on a mass. For example, a force of 1 g on an object sitting on the Earth’s surface is caused by the mechanical force exerted in the upward direction by the ground , keeping the object from going into free fall. The upward contact force from the ground ensures that an object at rest on the Earth’s surface is accelerating relative to the free-fall condition. (Free fall is the path that the object would follow when falling freely toward the Earth’s center). Stress inside the object is ensured from the fact that the ground contact forces are transmitted only from the point of contact with the ground. Objects allowed t
…would temporarily starve the engine of fuel and cut it off.
This was partly solved with ‘Miss Shilling’s orifice’, named after its designer, which attempted to reduce the fuel rich mixture and maintain engine power. Further solutions were added, but the problem was never completely solved.
German aircraft like the Bf 109 were fuel injected, meaning they produced power at any orientation. They would often exploit this weakness in aircraft like the Spitfire by simply nosing down to avoid an attack.
Check out the simple but brilliant fix here:
Miss Shilling’s orifice – Wikipedia
Fuel flow restrictor retro-fitted to Merlin engines The Rolls-Royce Merlin engine originally came with a direct carburettor, prone to cut-out due to fuel flooding in negative G. Miss Shilling’s orifice was a very simple technical device made to counter engine cut-out in early Spitfire and Hurricane fighter aeroplanes during the Battle of Britain . While it was officially called the R.A.E. restrictor , it was referred to under various names, such as Miss Tilly’s diaphragm or the Tilly orifice in reference to its inventor, Beatrice “Tilly” Shilling . Engine cut-out problems [ edit ] Gun camera view of a Spitfire firing at an He 111 bomber. A sudden loss of power caused by a slight downward pitch of the nose could be fatal in such a situation. Early versions of the Rolls-Royce Merlin engine came equipped with an SU carburettor . When an aeroplane equipped with such an engine performed a negative G force manoeuvre (pitching the nose hard down), fuel was forced up to the top of the carburettor’s float chamber rather than down into the engine, leading to loss of power. If the negative G continued, fuel collecting in the float chamber would force the float to the floor of the chamber. Since this float controlled the needle valve that regulated fuel intake, the carburettor would flood and drown the supercharger with an over-rich mixture. The consequent rich mixture cut-out would shut down the engine completely.  During the Battles of France and Britain , the German fighters had fuel injected engines and therefore did not suffer from this problem as the injection pumps kept the fuel at a constant pressure. The German pilots could exploit this by pitching steeply forward while opening the throttle, a manoeuvre that the pursuing British would be unable to emulate. The British countermeasure, a half roll so the aircraft would only be subjected to positive G as it followed German aircraft into a dive, could take enough time to let the enemy escape. The Tilly orifice [ edit ] Complaints from pilots over engine cut-out during dives and brief inverted flight led to a concentrated search for a solution. Engine manufacturers Rolls-Royce produced an improved carburettor, but this failed in testing. It was Beatrice ‘Tilly’ Shilling , an engineer working at the Royal Aircraft Establishment at Farnborough , who came up with a simple device which could be fitted without taking the aircraft out of service. She designed a thimble-shaped brass flow restrictor (later refined to a flat washer) with precisely calculated dimensions to allow just enough fuel flow for maximum engine power. It came in two versions, one for 12 psi manifold pressure and another for the 15 psi achieved by supercharged units.  While not completely solving the problem, the restrictor, along with modifications to the needle valve, permitted pilots to perform quick negative G manoeuvres without loss of engine power. This improvement removed the RAF’s Rolls-Royce Merlin -powered fighters’ drawbac
8. Look under 4 and 5…
9. It had terrible range from low internal fuel storage and because if its small/slight build, could nt carry adequate external fuel’drop tanks, limiting it to air-to-air anf taking away bomber escort and ground attack. (The ground attack role was also compromised by #1 above, as like most liquid-cooled fighters, couldn’t take the pounding of anti-aircraft cannons.)
TheSpitfire had extremely short legs. Its low internal fuel capacity, 85 gallons, compared with:
P-38J 410 gal
P-47D-20 305 gal
F4U-1 351 gal
P-51D 269 gal
(And each of these was later designed to carry much more internal drop tanks,) limited its ability and wouldn’t let it fly very far or fight for very long, a huge weakness throughout the war. This greatly limited its radius of action for bomber support or lan-range fighter sweeps once the action had moved away from England and the Continent. The Spitfire and Bf109 had been designed to meet the requirements of the time (pre war), that is, as short-range interceptors, and had never been imagined as having to fly great distances on, for example, escort missions. Whereas the P-51, from the outset, was designed with range and endurance in mind, which even then, was improved as the needs dictated.
Being short on fuel, the Spitfire’s major drawback beside bomber escort, was in the fighter-comber/ground attack role, due to its low weight of ordnance or fuel-carrying capability.
Modifications were made to the late Mk V series to carry one centerline 500 lb bomb or a 170 gallon drop tank. In the 5,665 Mk IXs built, the bomb load was finally increased to 1,000 lbs. (For comparison a P-47 can carry 3000 lbs and a F4U Corsair can carry 4000 lbs of bombs/rockets.)
(Above: Modified Mk V w/two wing bombs.)
Several later models carried six wing racks for 5-inch HVAR rockets. This limited external stores armament list remained the same until after the Mk XVI model ended wartime production.
(Above: Six wing racks for 5-inch HVAR rockets.)
(Above/Below: Spitfire Mk IX MK210 with metal drop tanks during tests in USA)
Early Seafires could remain on station for only 45 minutes under combat conditions. The Sea Hurricane was barely better, offering only one hour CAP patrols. The Martlet (Grumman F4F Wildcat) could stay on station for 2 hours 15 minutes, while the Fulmar averaged 2 hours.
As a result, the Seafire was initially reserved for defensive missions: The longer-ranged Martlets and Fulmars maintained the CAP, while the Seafire filled its sibling’s interceptor role – sitting on the deck ready to leap into action once the first radar reports started rolling in.
So the Royal Fleet Air Arm guys near Malta improvised a RAF-style “slipper” drop tank fitted to the belly of some Seafires:
“We found that it could hold 90 gallons of 100 octane fuel. This was more than the Spitfire carried in its internal tanks. A closer study of the jettison arrangements showed that a Bowden cable release in the cockpit let go the lifting ring — stressed to three tons breaking strain — in the top surface of the tank. The tank then slid backwards onto two lugs sticking out two inches from the fuselage underside. The nose of the tank then dropped and the airflow forced it downwards and clear of the fuselage underside. The slightest skid, we thought, and the whole thing would come clear of the two lugs, slide back and hit the tail. However , the Spits would now have a range of 400 miles and would allow a fly-off to Malta well before we got to ‘bomb alley’.”-Commander ‘Mike’ Crosley.
The Seafire was not a good carrier aircraft, too lightly built, too fragile to take carrier landings/poundings and the Merlin was not a good carrier engine and needed replacing every 200 hours, easily twice as often as land-based Spitfires, from the extra boost stresses and over revving of take-offs, and the pounding/jarring/vibration of carrier landings and operations.
She flew like an Arabian stallion compared to the heavier, workhorse feel of the American fighters, but she was too “short-legged” in the fighter-bomber, ground attack and escort bomber roles. This severely hurt her overall performance, versatility and standing with other WWII fighters.
10. It was never a great high altitude fighter, limited to most of its Marks to under 37,000 feet where the Bf 109 G could perform at 39,000 feet, P-51 could perform at 42,000 and the P-47 at 43,000 feet.
This called for two principal modifications, the introduction of a pressurized cabin and the use of a Merlin suitably rated for higher altitude. The first version of the Spitfire so equipped, was the Mark VI derived directly from the Mark VB, as a result of work on pressure cabins at the Royal Aircraft Establishment and Supermarine during 1940-41. At the R.A.E., a Prototype was fitted with a Merlin 47 (the high rated version of the Merlin 45 with 1,415 HP, with a Marshall compressor, “blower”, to presurize the cockpit,) with a four-blade Rotol propeller with Jablo blades and a pressurized cabin, the Mk VI was capable of reaching 39,200 ft.
(Above: Spitfire VI, not just to get parity with the Bf 109s but also to go after high-flying German bombers.)
The production Spitfire VI also had an increase in wing area to improve controllability at high altitudes, the wing being of pointed planform with a span of 40 ft. 2 in. The pressure cabin was contained between the bulkheads fore and aft of the cockpit, and a special non-sliding hood was fitted to simplify the sealing problem. A Marshall blower provided a cabin differential of 2 lb./s. in., reducing apparent altitude from 40,000 feet to 28,000 feet. In other respects including armament the Spitfire VI was similar to the Mark VB.8
The Spitfire VII (Type 351)…
(Above: Spitfire prototype Mk VII.)
…was a more extensive re-design for high-altitude work, and was the first of the Spitfire series intended to make use of the two speed Merlin 60 series of engines. These two-stage engines were coupled with a re-designed cooling system which showed itself in the enlarged air intake under the port wing matching that to starboard. The wing outline remained similar to that of the Spitfire VI, but the ailerons were reduced in span. The chord and area of the rudder were increased and the elevator horn balance was extended. Structural changes were made to the fuselage to take the increased engine loads and a double-glaze sliding hood was fitted to the cockpit. The retractable tail wheel first developed for the Spitfire III, was applied in production for the first time on the Mark VII and the universal C -type wing was employed. Maximum speed jumped by 44 mph to 408 mph and normal loaded weight climbed to 7,875 lbs.
Eventually 43,000 feet was reached, on par with the P-51 and P-47 and superior to all German aircraft including the Fw 190D, but too little too late, as msot f the war it had struggled literally under the Bf 109s.
And as for…
11. A very good Diver and…
12. As for the Roll, I pretty much answered these in the beginning.
Thanks for taking the time. I have to thank and acknowledge three dear departed friends and mentors for the majority of these insights and knowledge:
“Corky” Meyer who was was Grumman’s top test pilot through WWII/Korea and beyond,
Gunther Rall, top German ace, who knew the Spitfire well from close acquaintance during the Battle of Britain,
and Jeffrey Quill, the top Spitfire test pilot and combat pilot. I coincidentally just answered this yesterday about Mr. Quill:
2 thoughts on “Flt. Lt. D.J. Watkins, DFC, CdG avec Palme”
I worked at Applecross for a year in 1972, where he was the warden. Very modest man for all his achievements.
I was at Applecross in November 1973 ,with Kingsridge secondary school,Drumchapel,Glasgow.
Desmond and his lovely wife were fantastic and very underestimated people.
A great example to young men.