No Spitfire?
- Thread starter tomo pauk
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fastmongrel
1st Sergeant
Problem with passing Merlin production to Napier's is that Napier's didn't have the facilities to mass produce engines. When English Electric took over Napier's they transferred Sabre production to a new factory in Liverpool.
I have both rifles, the SMLE is better, the P14 is a backward step.
- Thread starter
- #484
An H16 engine might've been interesting for the airforces of the day - not as long, complicated and expensive as the 24 cylinder engines, with short & stiff crankshafts to better withstand stress, and with not too big cylinders so they can turn better rpm.
Not sure what were the "short stroke pistons" there. The similarly big DB 603 run at 2700 rpm.
Big engines can offer a 'cushion' with regard to the fuel available - not everyone was sure that their fuel octane/performance rating will go up. Thus we have the AM-38 making much better power than the smaller VK-105 engines of the day and on the Soviet fuel available. Or the DB 603 making better power than DB 601/605 under the same conditions.
Fairy Monarch was a H24, the Prince was a H16
Fairey Monarch - Wikipedia
Devoid of the problems of complex crankshafts and Conrod forks as well as sleeve valves.
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wuzak
Captain
The Fairey P.24, aka Monarch, had its fair share of problems.
Not sure that the H16 ever existed. The picture on the Prince page is actually the H-24 Monarch. It had an odd exhaust arrangement, where the middle 4 cylinders on each bank shared 2 outlets.
There was a V-12 Prince, which was the basis for the P.24.
Fairey P.24 Monarch Aircraft Engine
Shortround6
Major General
The AM-35/38 had different length stokes due to the articulated connecting rods. One bank of cylinders had over 6mm more stroke than the other. I gave the piston speed for the "short" stroke.
Big engines can offer a cushion, they also weigh more. AM-35 went over 1800lbs, the AM-38 was over 1900lbs the VK-105 went under 1300lbs for the early versions.
DB603 went over 2000lbs.
The bigger engines do have a better power to weight ratio, just not quite as good as a quick glance looks.
And in some cases it is two big engines or 3-4 small engines.
It is possible to make a big, light engine. It just won't stand up to high power or high rpm.
The BMW VI engine that the AM-35 is supposed to trace it's linage to was slightly larger (longer stroke on the articulated pistons) but only weighed 1124lbs.
of course it only ran at 1700rpm (for one minute) and gave 750hp at sea level (no supercharger)
Hispano 12Y was 2200 cu in compared to the Griffons 2240 cu in but the 12Y-45 weighed 1135lbs compared to the Griffon II (single stage/two speed) 1790lbs.
wuzak
Captain
The Buzzard, also of 2240 cu in, weighed 1140lb. The R weighed 1640lb.
ThomasP
Senior Master Sergeant
All this talk of engine development makes me ponder what would have changed if, for example, RR had pursued their early X16-cylinder engines wuzak mentioned up-thread. If RR had started development in the early-1930s, they should have at least found out the problems involved and worked out solutions, before they started on the Vulture. When the demand came along in the mid- to late-1930s I think that would have had a major effect on the practicality of large displacement powerful engines. How would a successful X16 design have affected the Kestrel/Merlin/Griffon path? Food for another thread maybe.
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wuzak
Captain
If they went ahead with the Eagle XVI then it is unlikely that the Kestrel would have been.
One of the solutions that Rolls-Royce considered for fixing the Vulture was to go to a pair of fork and blade rods per crank throw. But they didn't have the time or resources to spend on that.
Another solution that may have been considered is that used on the Pennine. It had one piece master rods (like some radials) and a built up crank.
EDIT:
The fork and blade rod arrangement would have been like that used on the Allison V-4520.
Allison X-4520 24-Cylinder Aircraft Engine
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- #491
Okay, thanks.
The difference in price and/or in 'producibility' was probably more pronounced when 14 cyl radials were compared with 18 cyl radials. People were still making the 18 cyl radials since power was the main requirement.
If one needs two smaller engines to do a job where one bigger engine can do it (in quest for extra performance and/or firepower and/or extra range), the economy favors a big engine. A 1800 lbs engine can propel a 4-cannon fighter to 400 mph far easier than a 1300 lbs engine could hope for, under the same technology (materials, fuel, S/C, aerodynamics) of the day, unless we have two of 1300 lbs engines on a single airframe.
I don't favor the light engines either.
Shortround6
Major General
RR Condor of 1918-1930
327 made
2137 cu in
1380lbs
MK III gave 670hp at 1900 rpm, no supercharger and absolute crap fuel.
Most of the European/British engine makers had a large engine (or more than one) in their history.
What they learned or didn't learn may have varied and technology was constantly evolving. the Aluminum alloys of the mid 30s were not the alloys of the mid 20s, they stopped using castor oil as an engine lubricate, heat treatment changed and so on.
One large engine could at times replace two smaller ones, and sometimes to great advantage.
But sometimes an engine was a dead end, perhaps too complicated or it took long to develop and bring to market and had been passed by.
- Thread starter
- #493
It's diesel version would've made a fantastic tank engine for ww2.
V12s were very simple engine when looked at many competing designs, like H16, let alone X24, H24 or W24 engines. Probably simpler than 18cyl radial engines.
Them's Fighting Words!!!
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- #495
One can chase away a Croat from the Balkans, but it is very hard to chase away Balkans from a Croat...
Shortround6
Major General
the physical layout is certainly simpler. It is the details that get complicated on many engines.
Lots of pictures of the Condor.
Rolls-Royce Condor IA, V-12 Engine | National Air and Space Museum
Take notice of picture 5.
4 valve head. but is a good one?
Like Bristol RR seems to be putting one intake and one exhaust valve on each side of the head? unless the head was semi spherical instead of pent roof?
size/shape of exhaust ports? intakes any better?
a longer description of the engine and changes made is here.
all-aero
The Condor used the older bore to stroke ratio rather than the bigger bore but shorter stroke (but still under square) ratio on the Kestrel, Merlin and Griffon.
size of valves needed to breath on a 1900rpm engine are different than the ones needed on a 2750-3000rpm engine.
Details like harmonic vibration, cylinder cooling (a 16 cylinder of the same displacement as a 12 is easier to cool) intake tract design and other things can complicate the "simple" V-12 to where a 16 or 24 cylinder engine looks attractive. Of course some designers under estimated the problems of the 16 and 24 cylinder engines
18 cylinder radials looked simple, just stick two 9 cylinder radials together, what could go wrong
- Thread starter
- #497
Seems to me that intake valves were towards the inside, and exhaust valves were towards the outside on the Condor.
No problems with that. Engineers have years and years to improve the engines' design or to cook something better of the similar shape - nothing earth-shattering about that notion.
Details like harmonic vibration, cylinder cooling (a 16 cylinder of the same displacement as a 12 is easier to cool) intake tract design and other things can complicate the "simple" V-12 to where a 16 or 24 cylinder engine looks attractive. Of course some designers under estimated the problems of the 16 and 24 cylinder engines
18 cylinder radials looked simple, just stick two 9 cylinder radials together, what could go wrong
With V12 engines, there is a good deal of 'institutional knowledge' within companies for people to compare stuff by late 1920s/early 1930s. V12s were also used on luxury cars. Knowledge about 16, 18 let alone about 24 cylinders was small to non-existent; greater number cylinders and/or banks will tend to drive price and complexity of engine upwards very fast. Granted, there is a practical ceiling for engine displacement vs. weight/complexity/price, my point was that a working big V12 was too good of an opportunity (if the opportunity actually existed - eg. does not apply for Japan or USA in the 1930s/40s) to pass.
Shortround6
Major General
you are quite right, but what is the shape of the combustion chamber? Modern pent roof chambers have the intake valves on one side of the angle and the exhaust valves on the other.
Maybe it makes no difference?
At any rate, Rolls had made a V-12 similar in size to the later Buzzard/R/ Griffon and had changed quite a few things. They were also able to get similar power out of a smaller-lighter V-12 (the Kestrel) 5-6 years after the Condor and probably got very similar power to weight out of the Kestrel pretty early.
During the 20s some of the engine makers could build big engines, convincing air frame makers (or air ministries) to use them was something else. Not for want of trying. Condors were used in 23 different aircraft. But often prototypes or small production runs. At times the air frame was a fault (Hawker Hornbill, only single seat fighter to try to use the Condor engine) or governments/ companies weren't ready to sink big money into single engine aircraft or even big twins. There wasn't a big market in 20s for 600hp engines and larger.
Most of the V-12 cars came late and offered nothing to an aircraft engine maker. R-R made one V-12 car engine starting in 1936. It was 447 cu in and while aluminum it used push rods from one cam in the V.
Cadillac made a V-12 in 1931 but it shared tooling with a V-16 made at the same time. The V-12 was 368 cubic in and shared a 45 degree bank angle with the V-16. Not good for an even firing order but in a 135hp car engine it could be dealt with. It also used one camshaft.
Just like Sir Roy Fedden went off an a tangent with sleeve valves some designers went off on tangents for multi cylinder engines, swapping price/complexity for solutions of perceived problems of the time they designing. Halford was a big proponent of multi cylinders. Yes he got 340hp from a 539 cu in engine but it weighed over 700lbs. That weight would have gotten an A-S Cheetah. a P & W R-985 Wasp Junior or a Wright R-975 Whirlwind. the last two making 400hp or more on 87 octane fuel.
The smaller cylinders offered more wall area and fin area for cooling than an engine using larger cylinders. The valve area to displacement of the cylinder was considered better.
P&W made a small number of large cylinders on an 1860 cu in 9 cylinder and had so many problems they never went over 156 cu in on a cylinder again on an air cooled engine.
Vibration problems were not well understood often high rpm-multi cylinder engines seemed to offer advantages. For some reason the frontal area of an engine seem to occupy a important place in design's minds even though cowlings were often lousy (as were radiators) in the 30s and a poor cowling /radiator could easily negate a few percentage points in frontal area.
The spitfire does seem to have been fast tracked by the Air Ministry. For instance the F10/35 specification for the spitfire of 1935 was the 10th specification initiated in 1935 and did not require a competition, in fact a contract funding the prototype had been issued beforehand. The Defiant specification was F9/35 actually preceded the Spitfires but a fly off competition was required.
For the Spitfire: On 1 December 1934, the Air Ministry issued contract AM 361140/34, providing £10,000 for the construction of Mitchell's improved Type 300, design. On 3 January 1935, they formalised the contract with a new specification, F10/35, written around the aircraft.
For the Defiant: P.82 Boulton Paul, having been focused on turret-equipped aircraft for some time, decided to make a submission for Specification F.9/35; their design was given the company name of P.82. The proposed fighter was similar in size and appearance to the more conventional Hawker Hurricane, differing in weight primarily due to the use of turret-based armaments.
Of the seven designs tendered, the Air Ministry ranked the P.82 as being the second-best submission, after the Hawker Hotspur but ahead of others such as Armstrong Whitworth's twin-engined design. The Air Ministry wanted several designs investigated and the production of two prototypes of each but the associated costs involved in this preference were in excess of the funding thus special permission from HM Treasury was sought.[ The Treasury agreed to finance the completion of seven prototypes (two Hawker, two Boulton Paul, two Fairey and one Armstrong Whitworth) but only prototypes of the two most promising designs, the P.82 and the Hotspur, were ordered in late 1935. in 1936, Boulton Paul commenced assembly on the first P.82 prototype, K8310, at their new Wolverhampton facility; an order for a second prototype, K8620, was received by the following year.
So in reality Britain could have waited till 1935 to order prototypes of a new fighter, this is about 1 year latter than the spitfire. Assuming progress was as fast as the defiant Britain would have the new fighter in service in late 1939.
For the Spitfire: On 1 December 1934, the Air Ministry issued contract AM 361140/34, providing £10,000 for the construction of Mitchell's improved Type 300, design. On 3 January 1935, they formalised the contract with a new specification, F10/35, written around the aircraft.
For the Defiant: P.82 Boulton Paul, having been focused on turret-equipped aircraft for some time, decided to make a submission for Specification F.9/35; their design was given the company name of P.82. The proposed fighter was similar in size and appearance to the more conventional Hawker Hurricane, differing in weight primarily due to the use of turret-based armaments.
Of the seven designs tendered, the Air Ministry ranked the P.82 as being the second-best submission, after the Hawker Hotspur but ahead of others such as Armstrong Whitworth's twin-engined design. The Air Ministry wanted several designs investigated and the production of two prototypes of each but the associated costs involved in this preference were in excess of the funding thus special permission from HM Treasury was sought.[ The Treasury agreed to finance the completion of seven prototypes (two Hawker, two Boulton Paul, two Fairey and one Armstrong Whitworth) but only prototypes of the two most promising designs, the P.82 and the Hotspur, were ordered in late 1935. in 1936, Boulton Paul commenced assembly on the first P.82 prototype, K8310, at their new Wolverhampton facility; an order for a second prototype, K8620, was received by the following year.
So in reality Britain could have waited till 1935 to order prototypes of a new fighter, this is about 1 year latter than the spitfire. Assuming progress was as fast as the defiant Britain would have the new fighter in service in late 1939.
Shortround6
Major General
Which is too late.
Spitfire was in service in very early 1939. Two squadrons had received aircraft in 1938 but were not declared operational until early 1939.
By Jan 1st 1940 13 1/2 Squadrons had Spitfires.
18 had Blenheim fighters.
Only one had Defiants.
Even if things went amazingly well and things were speeded up by 6-8 months that leaves the British way short of modern monoplane fighters in 1939 and 1940.
There were 10 Spitfire fighter squadrons in early Sept 1939. Early aircraft were passed to No 6 and 7 Operational Training Units as newer production aircraft were issued to operational squadrons.
2nd Defiant squadron wasn't declared operational until the summer of 1940. If you use the Spitfire time line delayed about one year and you would have had about 10 Squadrons of this hypothetical fighter in service at the start of the BoB instead of 19 squadrons of Spitfires.
Can you make it up with some extra Hurricane squadrons?
Can you keep some Blenheim squadrons and Gladiator squadrons in service a number of months longer?
