WW2 with no Spitfire - Hurricane being primary interceptor

[RCAFson]

The Merlin 12 is NOT an early Merlin 45. It is a Merlin III using water/glycol instead of pure glycol as coolant and using a slightly higher supercharger gear on the Merlin III supercharger.

I never said it was, but the point is that it is an improved single stage engine, that would have boosted Hurricane I climb rates and performance.

First part is true but then every other two speed engine in the world had to be throttled back to change gears too, didn't they? The 45 CANNOT be run flat out from take-off. It can be run at 2850rpm at 9lb boost after take-off which is the same as the Merlin 12 or the Merlin XX.
How much of the 200lb installed weight is the engine, how much is the "extra length" and how much is the change in the cooling system from pure glycol to the water/glycol mix and any changes in the radiators? How much of the extra length is the two speed drive and how much is the extra length of the new intake elbow on the Hooker designed supercharger used on both the XX and the 45?

Having to throttle back will hurt performance during some specific operations, such as a climb to altitude to intercept or during pursuit/evasion - it most certainly is a disadvantage. Of course the 45 can be run flat out if the situation warrants it! In any event even during full throttle climbs at 9lb boost the XX must be throttled back while the 45 doesn't.

Lets make sure we are comparing apples to apples. Some planes fitted with the Merlin XX (like the Defiant) had to have bigger radiators installed to handle the extra power and that is before they pushed the boost up to 16lbs. Didn't Spitfires with Merlin 45s get bigger oil coolers than Spitfires with Merlin IIIs ?

It is difficult to make exact comparisons as aircraft naturally added weight due to increases in protection and other areas, but certainly the 45 doesn't have the clutch and two speed drive. If someone has more info on this, I'd certainly like to see it. A comparison of the late model Spitfire IIa and early Va would be interesting.

 

[Elmas]

Let's think the opposite: if in the Battle of Britain RAF had only Spitfires and no Hurricanes, with the same total number of aircraft.

R.R. Stanford Tuck, DSO, D.F.C. and Two Bars, suffered a shock for a landing against a dry-stone wall hidden by hawthorn.

"When finally he was discharged he suffered another shock: he had ben posted from 92 to 257.
And 257 was a Hurricane squadron!"
(italics in the book.....)

Interesting to read the differences between the moral among the Pilots of a Spitfire Squadron and a Hurricane Squadron.

Larry Forrester
Fly for your life
pag 156

of wich I have a copy signed by Stanford Tuck.

 

[RCAFson]

Another thing, the Merlin 60 series was designed for high altitude bombers. It was Hives who suggested that it be put in the Spitfire. I wonder if he would have been so enthused about sticking it in the Hurricane?

It's interesting to consider the performance of the Hurricane IIc with a Merlin 60.

With a Merlin XX, FTH at 9lb boost was about 21000ft for a TAS of 330mph and an IAS of 246 with ~1100hp (actually a bit less). A Merlin 60 would give ~1100 at ~30,000ft which should give about ~390 mph TAS. The Merlin 62 gave 1390hp at ~25000ft with 15lb boost so it should push the Hurricane II close to 370-390 mph. Maybe someone else can look at these figures.

 

[nuuumannn]

Even without hindsight, it was therefore, easy to make a case for a much more rapid expansion of RAF FC, and the most logical fighter to be mass produced was the easy to build, easy to repair, and easy to fly, Hurricane.

Aaah, yes, there was a serious expansion of the RAF pre-WW2; an order for 600 Hurricanes in an entirely new factory is a huge amount of aeroplanes for a peacetime industry to build, so, as I said, there would have been no difference in what actually happened until the war really got going. You still haven't answered who would build these aircraft and where. You're attempting to pull a rabbit out of a hat. Nothing would have been ANY different to the way things were pre-war because what was going on in Britain in the late 1930s WAS an escalation of military production, as a result of the rebuilding of the German war machine and the Munich Crisis. The performance deficiency of the Hurricane over the Bf 109 has everything to do with it; this would highlight a significant disadvantage Fighter Command pilots found themselves at, so measures would be taken to produce a better fighter, as what happened with the Fw 190.

It's interesting to consider the performance of the Hurricane IIc with a Merlin 60.

Stick a Merlin 61 (which was built for fighters, while the '60 was developed for the Wellington VI) in the Hurricane and you have to alter the cg since you now have a longer aeroplane up front, there's also less clearance for the propeller and the radiator and oil cooler installation is inadequate and reeds to be revised. Doesn't really seem worth it. Altering the Hurricane to this extent was a waste of effort - that's why it wasn't done. On paper, the Boulton Paul P.94 showed more promise as a single-seat fighter than the Hurricane. When the Defiant prototype had its turret removed to evaluate the stop-gap idea, its performance was on a par with the Hurri, so why go for an aeroplane with little or no real development potential than one/ones that had it? Evidence in this is that the Hurricane's physical design changed little (wooden to ali wings aside) between the Mk.I and the last variants.

 

[Aozora]

It's interesting to consider the performance of the Hurricane IIc with a Merlin 60.

With a Merlin XX, FTH at 9lb boost was about 21000ft for a TAS of 330mph and an IAS of 246 with ~1100hp (actually a bit less). A Merlin 60 would give ~1100 at ~30,000ft which should give about ~390 mph TAS. The Merlin 62 gave 1390hp at ~25000ft with 15lb boost so it should push the Hurricane II close to 370-390 mph. Maybe someone else can look at these figures.

Spitfire IX w/Merlin 61 at altitude: http://www.spitfireperformance.com/bf274speed.gif 402 mph at 30,000. More likely a Merlin 61 in a Hurricane would give 360-370 mph at the same height, not forgetting that the Hurricane would have climbed slower

But anyway this is irrelevant because, according to you:

The relative performance of the 109 and Hurricane is irrelevant.

So why bother considering performance figures?

The whole premise for this thread is that the UK decides not to build the Spitfire but to instead use the funds and factory space to build more Hurricanes.

Which as, has been explained several times, was not an historical or theoretical option.

 

[Shortround6]

I never said it was, but the point is that it is an improved single stage engine, that would have boosted Hurricane I climb rates and performance.

Yes it would but then the improvement would be some what less than the Improvement the MK II showed and since the MK Improvement wasn't good enough in the spring of 1941 that leaves you were?

Having to throttle back will hurt performance during some specific operations, such as a climb to altitude to intercept or during pursuit/evasion - it most certainly is a disadvantage. Of course the 45 can be run flat out if the situation warrants it! In any event even during full throttle climbs at 9lb boost the XX must be throttled back while the 45 doesn't.

I guess the British and every other air force that used two speed engines got it wrong then?
The two speed supercharger will give more power just about up until time the change gears. This means a better climb rate for 4-5 minutes before the gear change, how long does the gear change take? can the single speed plane catch up while the 2 speed plane is shifting? or in the last 1000ft or so before the shift? a some point after the shift the 2 speed is again making more power.

It is difficult to make exact comparisons as aircraft naturally added weight due to increases in protection and other areas, but certainly the 45 doesn't have the clutch and two speed drive.

Which is pretty well accounted for by the extra 65-75lbs of weight. Both P W and Wright managed to make 2 speed drives for their 1200hp radials that were under 50lbs.

Increasing the power of a liquid cooled engine by 20-30% (forget the 16lb boost levels) and NOT supplying increased cooling capacity is asking for trouble.

In 1940-41 you are playing a fine balancing game between the allowable boost and the fuel before detonation sets in. British 100 octane in 1940 was NOT 100/130. It was 100/115-120? depending on batch. American fuel was 100/100 or actually 100/97-105? or so? This is one reason the Merlin XX was approved for 12lb boost in LOW gear ONLY in the fall of 1940. Low gear not only takes less power to drive, it heats the intake air less. The cooler air is more dense and makes more power for the same boost setting. It also allows higher boost to be used before you hit the boost/temperature limit that leads to detonation.
Once they figured out HOW to measure the rich mixture response they could put it in the specification and begin to get better fuel,100/125 was a short term specification before the 100/130.

This is important for this time period as you can't just jack up the pressure to what you want unless the fuel will support it. And in 1940 engines might run fine at 12lbs boost with one batch of fuel and start suffering from detonation with another batch of fuel. This was part of what made the two speed superchargers so important. They could give more power over a much wider span of altitudes using the SAME pressure and fuel as a single speed supercharger.

 

[wuzak]

The two speed supercharger will give more power just about up until time the change gears. This means a better climb rate for 4-5 minutes before the gear change, how long does the gear change take? can the single speed plane catch up while the 2 speed plane is shifting? or in the last 1000ft or so before the shift? a some point after the shift the 2 speed is again making more power.

The need for throttling back is not so much for the shift, but because the new gear has a higher ratio and thus the supercharger needs throttling to prevent overboosting.

Assuming an allowed 9psi boost, the Merlin XX would have dropped back to 6 or 7psi boost before the change. After the change the engine is again back at 9psi boost, but loses power because it is being thrittled and the higher gear needs more power to drive. Thus it loses power and the plane loses speed.

Now, if the XX's FS gear was the same as the Merlin 45's gear they would have the same critical altitude. That is, after the shift they would have the same performance. However, the XX in low gear would have higher performance.

But the XX's FS gear had a higher FTH than the 45 - so there will be a small band where the 45 is superior, but apart from that the XX is superior.

 

[Aozora]

So do the two authors I quoted. no-one is above questionng, and there is no definitive answer to this problem, because the records many of the records kept for this period were destroyed. Thats what makes the problem difficult to unravel

What two authors have you quoted? I can only find one title you've alluded to; "History of Malta": if you are talking about Brian Blouet's "The History of Malta" AFAIK this is a general history of Malta and is not a specialised publication on the air battles.

Who said anything about nonsesne, except yourself.

So there's no misunderstanding, this is what you posted

The problem with this, is that there werent 27 to shoot down. Thats a bit of a problem with that account.

If that's not dismissing Shores Cull and Malizia as nonsense, what is?

I should say the same for you, you should read the accounts ivereferenced before dismissing them

How can anyone know what references you have used when you have not specified them?

 

[wuzak]

It is difficult to make exact comparisons as aircraft naturally added weight due to increases in protection and other areas, but certainly the 45 doesn't have the clutch and two speed drive. If someone has more info on this, I'd certainly like to see it. A comparison of the late model Spitfire IIa and early Va would be interesting.

Spitfire VA X.4922 was tested at 6450lb "operationally equipped". The report references an earlier test with Spitfire VA K.9788 as being at 6070lb, but no mention of its condition.

Spitfire IIA P.7280 was tested at 6172lbs, with no mention of loadout.

 

[wuzak]

Interestingly:

The Spitfire VA X.4922 shows a top speed of 375mph @ 20,800ft. (+9.0psi boost).

The Spitfire VB W.3134 shows a top speed of 371mph @ 20,100ft (+9.0psi boost).

The Spitfire VC AA.873 shows a top speed of 374mph @ 19,000ft (+9.3psi boost).

 

[wuzak]

Which as, has been explained several times, was not an historical or theoretical option.

I think if the Spitfire could have been delivered in quantiy more quickly the RAF may not have bothered with the Hurricane at all.

 

[The Basket]

I find the concept of the Spitfire being cancelled very believable and almost reasonable.

The following facts are points. ..
Hurricane was top notch when it first flew in 35 and the Spitfire prototype was a bit slower than original thought. Also the early marks of Bf 109 were underpowered and underarmed so the Hurricane was certainly no slouch.

2, 000 bhp fighters were over the horizon so why waste resources on another 1, 000 bhp fighter? Also plenty of schools of though on the advantage of turret fighters and twins like the Whirlwind which promised maximum firepower and plenty of performance.

Also Spitfire was slow to get into production and difficult to build so why bother? Also Spitfire wasnt rugged, short range and couldnt carry a heavy ground attack load. All minus points. So one could argue putting Spitfire in production was not the most obvious thing to do. Based on 1930s thinking.

 

[wuzak]

Hurricane was top notch when it first flew in 35 and the Spitfire prototype was a bit slower than original thought. Also the early marks of Bf 109 were underpowered and underarmed so the Hurricane was certainly no slouch.

Comapred to? Difficult to compare without a direct comparison or confrontation.

The Spitfire prototype managed 349mph. That is certainly less than the 350mph Mitchell estimated.

2, 000 bhp fighters were over the horizon so why waste resources on another 1, 000 bhp fighter?

2000hp fighters were a long way off in 1936. Neither the Vulture or Sabre had run by that stage, so staking the future on thise would have been risky.

The Spitfire was a more risky design than the Hurricane. It was from a company unused to series production, it used new construction techniques but it also promised far higher performance. The Hurricane was a safe choice, and would serve as a backup if teh Spitfire failed.

Also plenty of schools of though on the advantage of turret fighters and twins like the Whirlwind which promised maximum firepower and plenty of performance.

The turret fighter concept came into vogue after the Spitfire and Hurricane were already being built as prototypes. In the end the Boulton Paul Defiant was put into production as well as the Spitfire and Hurricane. Prototype testing revealed how the turret affected performance.

Cannon versions of the Spitfire and Hurricane were proposed to the specification for the Whirlwind. No doubt that the Whirlwind offered high performance and heavy firepower, but would it be as manouevrable as a Spitfire or Hurricane? Westland dragged their feet enough that the MAP looked for alternatives as stop gaps, settling on the Beaufighter.

Also Spitfire was slow to get into production and difficult to build so why bother?

Because it was clearly the superior aircraft.

Also Spitfire wasnt rugged, short range and couldnt carry a heavy ground attack load. All minus points.

Ground attack was not considered for either the Spitfire and Hurricane in the 1930s. The short range was not a minus point because it, like the Hurricane, was to be a defensive fighter.

So one could argue putting Spitfire in production was not the most obvious thing to do. Based on 1930s thinking.

The 1930s thinking behind the Spitfire and Hurricane was for an interceptor to shoot down unescorted enemy bombers. The use of radar negated the need for standing patrols and thus long range, and put an emphasis on climb performance.

The climb performance of the Spitfire was outstanding, quite a bit better than the Hurricane's. And most of its other performance paramaters were very much better than the Hurricane.

The Spitfire fit the 1930s concept of a defensive fighter perfectly.

 

[nuuumannn]

Interesting points from both of you, Wuzak and Basket, although I have to agree with Basket regarding how the Hurricane was perceived at the time - it was considered one of the best, if not the best front line fighter in the world when it entered service. Although even thought the Spit was lagging a bit in production, it's potential was unmistakeable and it was only a matter of time before the issues were worked out, so why bother? Because it had so much promise.

Regarding the turret fighter; the first one was the Hawker Demon that entered service in 1933, which the Defiant was designed to replace, but tactics worked out by the RAF pre-war stated that the Daffy was to attack unescorted enemy bombers in conjunction with single-seat fighters, which, once the Daffys had broken up the bomber formations, would dive upon the stragglers. If only that scenario transpired in mid 1940...

 

[wuzak]

The Spitfire's troubled early production was the main reason why the MAP would have considered cancelling the Spitfire, and was very much the reason why it was considered that there would be no more Spitfires after the first order. But then the Whirlwind was late, and the Typhoon was some time away and it was clear that the Hurricane was no longer going to be competitive.

 

[FLYBOYJ]

Good discussion folks!

I've always believed the Hurricane was one of the most underrated fighters of WW2. I think it "might" have been able to fulfill the role of the Spitfire, but very hard pressed with a lot higher casualty rate. I don't see much more "stretch" evolving from the basic design.

As far as the Spitfire being difficult to build - I think it should be examined as harder to build when compared to the Hurricane. The Spitfire had some unique manufacturing characteristics, but nothing that could be conquered in time by skilled workers, so this claim of the Spitfire being difficult to build is a bit stretched. You want to see a difficult aircraft to build - look at the P-38.

 

[nuuumannn]

Yep, I don't disagree, Joe and Wuzak, but regarding the Spit being difficult to build, it was what was relative to the British aviation industry at the time, used to building fabric covered steel tube biplanes - of which construction the Hurricane (partially) shared, in not the same numbers as aircraft built in the USA, but also specifically regarding Suparmarines' own work force. That firm had a reputation for long waits between orders and production and frustration would have amounted from the delay in getting the thing out the door.

 

[wuzak]

I've always believed the Hurricane was one of the most underrated fighters of WW2. I think it "might" have been able to fulfill the role of the Spitfire, but very hard pressed with a lot higher casualty rate. I don't see much more "stretch" evolving from the basic design.

It may have been able to hold the line in 1940, but beyond that?

As far as the Spitfire being difficult to build - I think it should be examined as harder to build when compared to the Hurricane. The Spitfire had some unique manufacturing characteristics, but nothing that could be conquered in time by skilled workers, so this claim of the Spitfire being difficult to build is a bit stretched. You want to see a difficult aircraft to build - look at the P-38.

I think the difficulty in producing the Spitfire was threefold.

1) Ths stressed skin construction was new to Supermarines, and quite new in Britain
2) Supermarines were a small concern (albeit owned by the huge Vickers company) and had little or no experience in making production aircraft. Those that had gone before were produced in small numbers.
3) The wing involved compound curves which proved difficult to get right.

 

[wuzak]

A quick look through Supermarine's catalog shows that they made 740 Walrus between 1936 and 1944.

Before that the aircraft were mainly in small numbers, except the Southampton flying boat - 83 of which were built between 1924 and 1934.

 

[wuzak]

The RAF also did not, at thattime, put all its eggs in one basket.

Maybe if there was no Spitfire there would have been the Bristol Type 146. Or the Martin-Baker M.B.2. Or the Vickers Venom.