Why did the RAF put so many resources into the Hurricane?

[stona]

I've read through the thread and very interesting it is. I do think there is a tendency to overthink the question.

The British persevered with the Hurricane because it was a proven design. Factories were tooled up to produce it. It served a useful purpose in many theatres (including the Mediterranean) at a time when alternatives were not available in numbers or not available at all.

Essentially, needs must. The Hurricane was a better aircraft than some are giving it credit for. It was adequate against all but the most advanced German fighters, and a vanishingly small number of advanced Italian fighters which it probably never met.

Hindsight is a wonderful thing, but not afforded the decision makers at the time. In the 'big picture' the Hurricane continued in production for the same reason that the M4 tank did. Both were wartime expedients.

Cheers

Steve

 

[Ascent]

The hurricane was 'good enough' and the factories were already producing it.
There's no point stopping production of an aircraft that can still fulfill its function to tool up for something else when you need every fighter you can get.

 

[Kevin J]

The Sea Hurricane IIc did the same 342 mph at 22000 feet that a Hurricane IIa did at the same height. It had the added burden of an arrestor hook that cost 6/7 mph depending on altitude. The standard IIc did 336 mph., 6 mph less than the IIa. Add 7, 6 and 342 and you get 355 mph for the Hurricane IIa with individual exhausts.

Also don't forget that Superarine got the initial Seafire LIII up from 341 to 358 mph although I can't quite remember what they did to achieve them. IIRC one was individual ejector exhausts, short barrel 20 mm cannon and removing 2 of the blisters on the wings for the no longer required cannon.

 

[tomo pauk]

The Sea Hurricane IIc did the same 342 mph at 22000 feet that a Hurricane IIa did at the same height. It had the added burden of an arrestor hook that cost 6/7 mph depending on altitude. The standard IIc did 336 mph., 6 mph less than the IIa. Add 7, 6 and 342 and you get 355 mph for the Hurricane IIa with individual exhausts.

Hurricane II with 12 guns was good for 330 mph, yet we're to accept that Sea Hurricane IIc was faster despite being navalized? Unless someone can provide a datasheet or test report to prove the 340+ mph mark for the S.H. IIc, I don't buy it.

 

[nuuumannn]

My estimate on top speed 355 mph. Okay for the Far East.

Waste of time, Kevin. You could do better by fitting a Griffon to it and getting an even better top speed, as there were plans to do so, but again, you're missing the essential fact that if you divert work force and resources to attempting fixing the Hurricane, then what's not being worked on or built? The Typhoon? The Tempest? The Fury? And those Griffons, what are they not going into? Spitfires??? Sorry, the Spit XIV was one of the best fighters of the war.

All these companies had limited resources. It's like the ole Fw 187 debate, supporters of that aeroplane never explain what aircraft - likely the Fw 190, would not be getting built in the factories if the Fw 187 was put into production and arguably, the '190 was better and more versatile.

The Hurricane had a good production run and utilisation, as Ascent states above,

There's no point stopping production of an aircraft that can still fulfill its function to tool up for something else when you need every fighter you can get.

Besides, on the frontline, 'Okay' is never okay, but you go to war with what you've got, not necessarily what you want. Remember that in the Far East, the RAF also operated P-47s and Spitfire VIIIs and eventually XIVs.

 

[wuzak]

I would note that Hawker Typhoons and Tempests used paired exhaust stacks, two cylinders sharing one outlet.

In both cases, only one cylinder exhausts through the ejector stack at any one time.

The two cylinders in the Merlin are 6.075in apart, so the ejector stack has to cover quite a bit of distance, and may not be optimised for one or both of the cylinders.

The shared cylinders on the Sabre, on the other hand, are one above the other. The exhaust ports actually meet in the block, before a single hole feeds a single exhaust stack.

It is akin to the two exhaust valve ports joining in the head of the Merlin to feed one ejector stack.

 

[Shortround6]

In both cases, only one cylinder exhausts through the ejector stack at any one time.

The two cylinders in the Merlin are 6.075in apart, so the ejector stack has to cover quite a bit of distance, and may not be optimised for one or both of the cylinders.

I think that some of us are over thinking this.
A Merlin cylinder is 2.25 liters (137.5 cu in) and once you run the supercharger up to 15lbs boost you have 4.5 liters of air and fuel in it. Once it burns you have hundreds of pounds per sq/in pressure trying to get out.
The fact that the exhaust path is 1-2 in longer for one cylinder than another doesn't amount to anything.
What matters (to the engine) is the size of the opening so the exhaust can get out ( the exhaust gases can fill the short stacks hundreds of times over.)
What matters for exhaust thrust is the speed of the gases leaving the open end of the stack (the nozzle). to large and the exhaust slows down. Too small and you may still lose velocity. It takes too long for the gases to get out instead of a short, sharp blast you get longer, slower release. we are still talking about fractions if a second here, very small fractions.

I would note that on the Merlin it appears that no two cylinders sharing a paired exhaust stack fired any closer than 240 degrees of crankshaft rotation so there shouldn't be much in the way of interference of the exhaust gases.

I would also note that when the US approved the WEP ratings for the Allison engine it was found that the exhaust outlets in the existing manifolds were too small. The solution in the field was to cut the openings back closer to the the engine and at angle (?) so that the sq/in of opening was increased. This increased the flow to reduce back pressure on the engine but probably didn't do anything for exhaust thrust.

Given the amount of time the exhaust valves are closed (456 degrees of crankshaft rotation) vrs time open (264 degrees) It doesn't look like having two cylinders share one outlet is that big a deal.

 

[Greyman]

Also don't forget that Superarine got the initial Seafire LIII up from 341 to 358 mph although I can't quite remember what they did to achieve them. IIRC one was individual ejector exhausts, short barrel 20 mm cannon and removing 2 of the blisters on the wings for the no longer required cannon.

Looking at the Seafire III tested at Seafire Mk. III Trials -- speed was probably beefed up by almost 20 mph in the Pacific:

+7.75 mph : switch out the triple ejectors with fishtails
+8.50 mph : remove snowguard
+2.25 mph : remove outboard cannon stubs
+1.00 mph : switch out the large-bulge cannon fairings for small-bulge ones

 

[Kevin J]

Looking at the Seafire III tested at Seafire Mk. III Trials -- speed was probably beefed up by almost 20 mph in the Pacific:

+7.75 mph : switch out the triple ejectors with fishtails
+8.50 mph : remove snowguard
+2.25 mph : remove outboard cannon stubs
+1.00 mph : switch out the large-bulge cannon fairings for small-bulge ones

Something like that, although IIRC the snow guard was 2.50 mph and bulges were 5.00 mph.

 

[Kevin J]

All I'm suggesting here is that there could have been small tweaks made to the Hurricane II for 1941/42 to make it more competitive with the A6M2 & K-43-I, for 1942/43 the Spitfire Vb/Vc Trop was needed out in the Far East and Pacific to counter the A6M3 & Ki-43-II; they weren't of course available until mid-late 1943. After 1942/43 the best use of the Hurricane II would have been as fighter bombers, intruders and anti-tank aircraft. Too little, too late as the saying goes in the case of the Asia-Pacific theatres.

 

[Greyman]

Something like that, although IIRC the snow guard was 2.50 mph and bulges were 5.00 mph.

Yeah digging around I'm seeing slight differences in gains from various changes of external equipment, 1-3 mph-ish.

But I'm always seeing +1 mph from the switch from large wing bulges to small.

 

[tomo pauk]

Let's not get over-excited about the exhaust thrust advantage of 6-per-side exhaust stacks vs. 3-per-side. Looking at the photos and drawings of Spitfires with one or another set, the 3-per-side seem to protrude more into slipstream = more drag = less speed.

 

[CatTheCool]

The pilots who got the hurricane prefered it to the Spitfire!

 

[tomo pauk]

The pilots who got the hurricane prefered it to the Spitfire!

In 1941-45? In all airforces that used both types? Sourced info taken from thousands of pilots?

 

[wuzak]

The pilots who got the hurricane prefered it to the Spitfire!

Mainly because they didn't fly the Spitfire....probably.

 

[Kevin J]

Mainly because they didn't fly the Spitfire....probably.

The Hurricane was adequate for the job of intercepting bombers and contesting the fighter escort, so why change over to the Spitfire during the BoB?

 

[Freebird]

The Spitfire was a far better machine. So why expend scare resources in building the Hurricane? Especially in 1940?

Because they needed fighter aircraft and didn't have the downtime & resources to retool factories for Spitfire

 

[pbehn]

The pilots who got the hurricane prefered it to the Spitfire!

I think it was more that expert pilots who knew what they were doing appreciated some of the Hurricanes properties, the Spitfire wasn't superior in every respect just most of the important ones.

 

[wuzak]

The pilots who got the hurricane prefered it to the Spitfire!

In 1941-45? In all airforces that used both types? Sourced info taken from thousands of pilots?

Mainly because they didn't fly the Spitfire....probably.

The Hurricane was adequate for the job of intercepting bombers and contesting the fighter escort, so why change over to the Spitfire during the BoB?

I think you've missed the point of the conversation.

CatTheCool suggested that those who were assigned to Hurricane squadrons preferred it to the Spitfire.

Tomo asked for the context of the statement, what period it covered and whether or not it was a result of a survey of pilots.

My suggestion was that the Hurricane pilot most likely preferred the Hurricane top the Spitfire because he had never flow a Spitfire.

Someone else may have knowledge to confirm, or not, that pilots in the BoB were trained in aircraft other than the Hurricane or Spitfire, and did not get into their fighter until attached to their squadron for training. Those that would continue onto Hurricane squadrons would train in Hurricanes, and those going to Spitfire squadrons would train in Spitfires.

No doubt those that flew the Spitfire preferred their aircraft to the Hurricane.

The question is, of those who flew both, how many preferred the Hurricane over the Spitfire. I'd suggest not a high percentage.

There was never a question or suggestion that one type be swapped for another in this conversation.

It would have been impractical for that to happen in the BoB in any case. As mentioned above, those in Hurricane squadrons were trained on Hurricanes, so swapping to Spitfires may have required some familiarisation time.

The main factor, however, was the production of the two types, in particular the lower rate of production of the Spitfire.

I have to doubt that had the possibility of having their squadrons fully equipped with Spitfires for the BoB, Park and Dowding would have jumped at the chance.

 

[pbehn]

The Hurricane was adequate for the job of intercepting bombers and contesting the fighter escort, so why change over to the Spitfire during the BoB?

They needed both, they could have won the BoB just with the Hurricane and had more loses and then what?, to win it with the Spitfire they needed to start building two factories about 1 year earlier certain that nothing could go wrong.