wuzak
Captain
No other changes to the airframe?
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The Hurricane IIa weighs about 200lb more than the Ia, so somewhere there's a lot more weight to the XX installation. Your own numbers:
No other changes to the airframe?
The Hurricane prototype showed the fin/rudder to be too small, hence the lower strake and fixed tailwheel. The better choice would have been to lengthen the fuselage so here is an opportunity to have two benefits from one minor change.A 'thin wing' Hurricane would probably have been the best solution. Post war, the RAE tested a laminar flow wing on a Hurricane, which cut wing drag by up to 26%.
The problem with a thin wing Hurricane is that you then have to find space for the fuel tanks. You then have to lengthen and rebalance the fighter, which upsets some of the handling. Similarly, a thinner wing will probably make the aircraft a little more nervous in pitch, upsetting the Hurricane's famous steadiness as a gun platform even more.
The you've got the radiators, also quite draggy. In 1941 the RAE tested a used Hurricane I that was about 15 mph down on its nominal top speed. In the wind tunnel, the RAE found that at 100/ft sec the aircraft had 12.9 lbs of extra drag inducing items, mostly down to poor seals, panel gaps, seams and the gaps at the propellor spinner.
They also found that at 100 ft/sec the Hurricane's radiator resulted in between 15.9 lbs at minimum drag position and 23 lbs of drag at maximum drag position.
For a WW2 fighter, the typical radiator produced about 11.5 lbs of drag (according to a post-war analysis by Napier) at minimum drag position. So the Hurricane is struggling with around 40% more radiator drag than that of a typical fighter.
To give you an idea of how important radiator drag was, the total drag 'bucket' of a Spitifre Vb in a wind tunnel 100 ft/sec was 65.5 lbs. The drag of the larger P-51 was about 50.5 lbs - the laminar flow wing and Meredith effect radiator, as well as better construction techniquest like flush riveting, means much less drag.
My own feeling is that if the money spent on Spitfire development (and procurement)was instead used to boost Hurricane development and production, that initially, up to about mid 1941, that the net result would have been positive, as more Hurricanes (3 Hurricanes for every two historical Spitfires plus historical Hurricane production), with better access to Merlin engine development (Merlin 12, 45), in a cleaned up Hurricane airframe would have resulted in a stronger RAF. However, once the 109F and FW190 arrive in numbers the situation gets a lot more difficult for Hurricanes unless it can accept a wing change. However even the existing design with modest changes might be able to hold the line until newer designs arrive in numbers.
Because it is cheap and easy to build and well suited to the Merlin, which is also cheap, reliable and easy to build.
A 'thin wing' Hurricane would probably have been the best solution. Post war, the RAE tested a laminar flow wing on a Hurricane, which cut wing drag by up to 26%.
Laminar flow wing section in WWII did not equate to 'Thin Wing' - The NAA 45-100 had a 15% t/c at ~ 50% Chord.
The problem with a thin wing Hurricane is that you then have to find space for the fuel tanks.
If the Hurricane used the same wing as the 51 it would have a LOT of room for fuel tanks and remove the lion's share of the drag
You then have to lengthen and rebalance the fighter, which upsets some of the handling. Similarly, a thinner wing will probably make the aircraft a little more nervous in pitch, upsetting the Hurricane's famous steadiness as a gun platform even more.
A Mustang Wing would introduce changes to the planform layout because of the CG changes due to the added fuel distribution. Hard to say whether the effect on the existing Static Margin would be positive or negative but the designers should solve easily
The you've got the radiators, also quite draggy. In 1941 the RAE tested a used Hurricane I that was about 15 mph down on its nominal top speed. In the wind tunnel, the RAE found that at 100/ft sec the aircraft had 12.9 lbs of extra drag inducing items, mostly down to poor seals, panel gaps, seams and the gaps at the propellor spinner.
They also found that at 100 ft/sec the Hurricane's radiator resulted in between 15.9 lbs at minimum drag position and 23 lbs of drag at maximum drag position.
For a WW2 fighter, the typical radiator produced about 11.5 lbs of drag (according to a post-war analysis by Napier) at minimum drag position. So the Hurricane is struggling with around 40% more radiator drag than that of a typical fighter.
To give you an idea of how important radiator drag was, the total drag 'bucket' of a Spitifre Vb in a wind tunnel 100 ft/sec was 65.5 lbs. The drag of the larger P-51 was about 50.5 lbs - the laminar flow wing and Meredith effect radiator, as well as better construction techniquest like flush riveting, means much less drag.
I wonder how they tested the Meridith effect in a wind tunnel at 60+ mph absent fully functioning engine/prop system to generate the heat exchanger temp and mass flow rate in the 450-600 feet per second range? Does the Napier report discuss this?
Between the thick wing and the radiator design, the Hurricane is always going to be slower than contemporaries on simlar levels of power. With a Merlin III, Spitfire was up to 40 mph faster than the Hurricane at altitude. Spitfire I: 362 mph with two-blade Watts prop. Hurricane I: 322 mph with the same set up.
no longer have such a cheap, easy to build design.
All Sea Hurricanes used during Harpoon and Pedestal used Merlin IIIs, so the Merlin 12/45 would have been a considerable improvement.
The Hurricane IIa weighs about 200lb more than the Ia, so somewhere there's a lot more weight to the XX installation. Your own numbers:
1515hp at 11,000ft with 16lbs of boost for the Merlin 45 vs 1490hp at 12,500ft at 16lb boost for the Merlin XX suggest that the Merlin 45 is more efficient at medium altitude at the same boost, but again the point isn't that the 12/45 is better than the XX, but that it is better than the III, and that the Hurricane could be fitted with whichever engine is best suited for a particular role.
That's debatable. Low altitude performance of the Hurricane Spitfire with a Merlin 45 and at 16lb boost would differ by about 20-30 mph; certainly the Spitfire is faster but then there's going to be a lot more Hurricanes.
Hurricane airframe design (for improved performance) was basically stopped in early 1940, yet most of it's contemporaries continued development for several years after that date - which doesn't seem to raise any eyebrows.
As to the original question, I think the RAF would have done very poorly if it only had the Hurricane.
If you look at the Battle of Britain, the Hurricane and the Spitfire shot down the enemy in at roughly the same rate, with the Spitfire marginally ahead. This is going from memory, mind you, so I could be a little off.
However, Spitfires loss rates were about a third lower than the Hurricane's. That means that during the BoB a Spitifre squadron could stay in combat longer and stay effective for longer. A pilot was just a likely to score a kill whether he was in a Hurricane or a Spitfire. However, he and his aircraft were much more likely to survive if they were in a Spitfire squadron.
For the RAF in the Battle of Britain, where the main concern was pilots rather than aircraft, I think the results could be near disasterous.
Hurricane/Spitfire loss rates during the BofB are skewed because the Hurricane was assigned primarily to 11 Group and so bore the brunt of the battle from forward airstrips where it was much more likely to be bounced than the predominately 12/13 Group Spitfires. Additionally when looking at Hurricane versus Spitfire stats during the BofB you must remember that the Spitfires got the Merlin 12 before the Hurricane got the Merlin XX and a Merlin 12 powered Hurricane would have performed better at high altitudes.
Hurricane/Spitfire squadron allocation by Group:
8 July 1940
10 group:
2 x H
2 x S
11 group
12 x H
6 x S
12 group
5 x S
5 x H
13 group
6 x S
3 x H
Jabberwocky made an extremely pertinent point, it was the pilots that were the main concern during the BoB, not aircraft losses.
Yes more fighters would have been a boon, but as previously posted, survivability was greater in the Spitfire.
And finally, who would want to write out of history the most gorgeous aircraft ever built?
The Merlin 12 would have given the Hurricane a better climb rate and better high altitude performance, which was exactly what was needed during the BofB. The Merlin 45 would have given the Hurricane/Sea Hurricane a substantial boost in performance compared to the Merlin III, and the Merlin 45 was more reliable than the XX because the two speed SC was prone to clutch and gear failures.The Merlin XX was in service use before the Merlin 45, they used the same supercharger and carburetor. The ONLY practical difference, performance wise, is the supercharger drive ratios. You want better engines for the Sea Hurricanes? Steal them from bomber Command who got the lion's share of the Merlin XX engines.
The Merlin 45 may have been more efficient at 10,000ft but it was less efficient both below and above that altitude. That is why they use two speed drives.
The Merlin XII would have been little help. It just used the slightly higher gear ratio of the Merlin 45 with the Merlin III supercharger.
You have to careful with such a comparison. At low altitudes the Hurricane II had around 100hp more than a Spitfire V at the same boost. And the Hurricane and Spitfire were starting to diverge, different armament with different weights and different drag, the fitting of tropical filters and the like make getting like to like comparisons hard.
That is not quite right, very few of it's contemporaries got airframe improvements. The Spitfire saw very little in the way of airframe improvement until after the MK IX. The P-40 had a slightly longer fuselage/tail on some later models but was essentially just a beefed up P-36 until the end of it's days ( which were at least a year too long). Bf 109 did get a rather extensive overhaul but it is about the only " contemporary" that did. Most of the Hurricanes true contemporaries (flying in 1935/36) were discontinued fairly early in the war . Many planes it flew with or against were started several years later. Even the Brewster Buffalo first flew TWO years after the Hurricane.
So despite their losses in France, and the BofB, FC added 12 new Hurricane squadrons to their OOB by the end of the BofB! This clearly shows how the greater production of the Hurricane was vital to FC's victory, and if all Spitfire production ( 3 Hurricanes for every 2 Spitfires) was converted to Hurricane production, FC would have grown even larger, faster. This would have freed more aircraft for overseas deployment and strengthened the Commonwealth's position in Malta, and Africa, sooner than historically.
This also clearly shows why the Spitfires were held back from France, and had rearward deployment in the BofB - poor Spitfire serviceability rates and low production meant that they couldn't be used in a war of attrition without suffering crippling losses, that couldn't be replaced.
I replied to Jabberwocky's point and showed how Spitfire deployment favoured it, as it was on average much less likely to get bounced, and much more likely to face Luftwaffe fighters operating at the extreme end of their endurance, ensuring that they couldn't stick around and fight.
Wrong: the reason no Spitfires were sent to France was because Dowding refused to allow his best fighter to be deployed in what he recognised was a lost cause, also noting that he released more Hurricane units to France with the greatest reluctance, and only after Churchill intervened. The Hurricanes that were in France were virtually wiped out, leaving the RAF with fewer fighters than it could have fielded in Britain to face the Luftwaffe.
Secondly the belief that the Spitfire had a poor servicability rate cf the Hurricane was just not true; eg:
The other assumption, that the RAF could have expanded faster had all Spitfire production been stopped is also erroneous; the RAF was having problems finding enough pilots to man the fighter units during the B of B and this situation would not have been solved simply by churning out more fighters and forming more fighter squadrons - if anything, the attrition rate of fighter pilots would have gone up if the only frontline fighter available was the Hurricane: the net effect, had Spitfire production been stopped in favour of the Hurricane, would have been a decline in the size and effectiveness of FC.
From this it may be seen that the Hurricane equipped by far the number of Dowding's squadrons (indeed outnumbering all other aircraft
combined), and that this numerical superiority existed in the strategically important No. I I Group, deployed in southern England and commanded by Air Vice-Marshal Keith Park, a New Zealander whose brilliance in handling fighter forces in defensive situations was to stand Britain in good stead throughout the war. What is not evident from the foregoing table is the state of we operational readiness of the various squadrons. For instance, in No. 11 Group's 17 Hurricane squadrons the aircraft serviceability rate stood at about 76 per cent, this despite the fact that well over 100 of the aircraft had experienced prolonged service in France; none of the Spitfires, with a serviceability rate of 72 per cent, had fought in France, although about 35 of them had fought relatively briefly over Dunkirk.
One further observation should be made with regard to Dowding's deployment of his fighters; it is also a reflection of the relative combat readiness of the Hurricane compared with that of the Spitfire. Owing to the more modern stressed-skin construction of the Spitfire it was realized by the Air Ministry that—at least in the early months of the war—Spitfires would require special maintenance facilities and servicing personnel; such facilities would first be made available at a few designated "Spitfire bases", of which Hornchurch, Duxford, Biggin Hill and Middle Wallop would be the first, and completed in that order. It may be seen from
the quoted Order of Battle that only Hornchurch yet possessed three Spltfire squadrons, and that at Filton, for example, the two Spitfire squadrons suffered a somewhat low serviceability rate—a state of affairs not assisted by "forward" airfields located Some distance away.
As powerful justification of Sydney Camm's design philosophy there were to be countless occasions in the coming months when Hurricane pilots were forced, through battle damage to their aircraft, to land at a forward airfield where only relatively primitive servicing and repair facilities existed, and yet within a few hours were able to take off once more in a fully serviceable aircraft. Unfortunately the same could not be said for the Spitfire—at least during the first half of the battle ahead—which frequently had to be dismantled and transported by road back to its Sector airfield if it had suffered anything but superficial airframe damage.
Mason, The Hawker Hurricane, P62-63
Yes, the Spitfire is prettier - no argument there...
I replied to Jabberwocky's point and showed how Spitfire deployment favoured it, as it was on average much less likely to get bounced, and much more likely to face Luftwaffe fighters operating at the extreme end of their endurance, ensuring that they couldn't stick around and fight.
Your numbers show that only 17% of Hurricanes were lost in aerial combat, and that facilities for repair were extremely primitive and lacked the need capability. An equal number of Spitfires would have suffered even higher over-all losses, even if their losses in combat were lower, which is of course, why they were not sent over - they were too expensive, too fragile when operated from grass strips, and their low production numbers meant that losses couldn't be replaced. If the RAF had sent over equal numbers of Spitfires, it would have been a catastrophic, and potentially fatal defeat for the RAF.