Hercules Engined Fighters

[Shortround6]

RAF fighters, to whom Bristol was hoping to sell the Type 153, were never outfitted with either Merlin VIII or the RM1M, so I'm not sure why you are mentioning these engines.

The Merlin versions were the only other game in town. The Mercury wasn't going to cut it.
If the RAF wanted more power down low there were ways to get it. and they knew how.
For the 1939 fighters they concentrated on better props and RR was working on the better engines, the Merlin XII and Merlin XX which did show up in 1940. Just about the same time as the Hercules III in the Beau \fighter.

Yes, Hercules III is needed.
Climb to 15-20k ft is what is needed in BoB, so I'll take it as-is.

Except the Hercules III isn't really a 1939 engine. It was barely a 1940 engine.

Overhauling one more temperamental engine vs. overhauling two less temperamental engine

Some of the Hercules engines were not even making 20 hours.
And some of the failures were a bit more spectacular the a normal overhaul. Like sheared off sleeve drives and sized sleeves/pistons.

 

[Shortround6]

1938>1942 fighters" describes probably the Hurricane and Spitfire (plus what was suggested by the other companies), not the 2000 HP fighters.

Except the 1938-42 fighters designs were the 2000hp fighters. They were what was intended to replace the Spitfire and Hurricane as of March 1938.
The aircraft companies designed accordingly.
The Sabre didn't develop as promised. delayed
The Vulture didn't develop as promised. Canceled
The Centaurus didn't develop as promised. Delayed (in part to get the Hercules running)
RR, using 100/130 fuel, filled in the gap and allowed the older airframes to keep working.

Planning on using 1300-1600hp engine in 1938 for planes to enter service in 1941-42 would have been seen as a waste of time.
In hindsight it was a lot more realistic.

 

[tomo pauk]

The Merlin versions were the only other game in town. The Mercury wasn't going to cut it.

The engine versions you've mentioned were not used by RAF; if they were, the performance above 10000 ft would've been awful.

f the RAF wanted more power down low there were ways to get it. and they knew how.
For the 1939 fighters they concentrated on better props and RR was working on the better engines, the Merlin XII and Merlin XX which did show up in 1940. Just about the same time as the Hercules III in the Beau \fighter.

Except the Hercules III isn't really a 1939 engine. It was barely a 1940 engine.

RAF (RR actually) certainly knew how - by application of 2-speed drives. Merlin X went into Whitley and, later, into Halifax, while the Merlin XX was a cure to the low performance of the Hurricane and Defiant, as well as for the Beaufighter.
Lumsden dates the Hercules III to 1939; granted, I don't know the exact production dates and quantities of the Mk.III.

Some of the Hercules engines were not even making 20 hours.
And some of the failures were a bit more spectacular the a normal overhaul. Like sheared off sleeve drives and sized sleeves/pistons.

I'd certainly love to see the actual data on (un)reliability of the Hercules engines in 1939-41.

Except the 1938-42 fighters designs were the 2000hp fighters. They were what was intended to replace the Spitfire and Hurricane as of March 1938.

The fellow member noted Hurricane and Spitfire as 1938-42 fighters.

 

[Deleted member 68059]

I hoped for a more specific reasoning



The comment of "and wont fit into any 1938>1942 fighters" describes probably the Hurricane and Spitfire (plus what was suggested by the other companies), not the 2000 HP fighters.

Its nearly twice as wide as a Merlin, and over 100kg heavier than even a two-stage Merlin.
I hope that helps with specifics. (Hercules = 55" dia approx vs Merlin at 29.8" wide and 41.2" tall)
giving over 14 vs 6.1 square feet frontal area, merlin area from profile not "X x Y"). Even the change from a Vulture to a Sabre needed so
many changes it became a different aircraft instead of an "option".

You can obviously "do it", but its going to be a new aircraft type, like a Bf109-X because of the CG
difference and totally revised fuselage section forward of the cockpit

 

[Shortround6]

The engine versions you've mentioned were not used by RAF; if they were, the performance above 10000 ft would've been awful.

And the performance of a Hercules II would have been awful at higher altitudes no matter how good it was at low altitude.

Lumsden dates the Hercules III to 1939; granted, I don't know the exact production dates and quantities of the Mk.III.

It takes a while to turn on the tap. For illustration Wright built 6 R-2600 BA engines in June of 1941, 12 in July, 22 in Aug, 17 in Sept, 45 in Oct, 135 in Nov and 206 in Dec.
was the R-2600 BA a 1941 engine or a 1942 engine? Great Britian is nowhere near the size of the US but a crated engine on the loading dock of the Bristol engine factor is not an engine installed in an airplane rolling out the door of an aircraft factory.

The fellow member noted Hurricane and Spitfire as 1938-42 fighters.

Kind of depends on definition. Spitfire first flew March of 1935, had been in design since Nov 1934 in the form we know today. 1st operational squadron was equipped at the end of 1938. (that took a few months just for the 1st squadron) and the 1st actual production example was flown in May 1938 (24 months after contract for 310 was placed), and accepted by the RAF in Aug 1938. On the 3rd of September 1939 the Royal Air Force had 306 Spitfires, of which 187 were operating in eleven fighter squadrons.
Air Ministry was putting out the requirements for the Replacement in March, 2 month before the production plane flew.

So is the Spitfire I a 1934/35 design? a 1936 airplane (date of order) or a 1938 airplane (1st squadron) or a 1939 airplane (a worthwhile number of planes in service) ?

Company XYZ may propose a modification of an existing prototype using a Hercules in order to speed things up in 1938. But the Air Ministry was already looking at planes with 2000hp engines and telling companies which engines they wanted to use. (A-S Deerhounds were not on the list)

 

[tomo pauk]

Its nearly twice as wide as a Merlin, and over 100kg heavier than even a two-stage Merlin.
I hope that helps with specifics. (Hercules = 55" dia approx vs Merlin at 29.8" wide and 41.2" tall)
giving over 14 vs 6.1 square feet frontal area, merlin area from profile not "X x Y").

There is no requirement that Hercules fits in the confines of the Merlin's cowling, so being wider is okay.
People at Lavotchkin 1st installed the 49.6in dia ASh-82 in the place previously occupied by a V12, and later also the 55in 18-cyl M-71 on the same place for the test purposes.
Hercules was about the same weight as the Griffon, and was shorter, so the moment of force on the firewall is smaller.

Seems like Hercules was not as much a 55in dia engine as it was the 55in dia R-2600, at least when looking here (R-2600-powered aside to Hercules-powered): Australian Beaufighters. This cutaway diagram notes 52in diameter of the Hercules.

You can obviously "do it", but its going to be a new aircraft type, like a Bf109-X because of the CG
difference and totally revised fuselage section forward of the cockpit

Yes, the bespoke aircraft would've been the best option. The Bristol Type 153 was probably the best bet (there is some information about the type in the 'British secret projects' book) - not too early wrt. Hercules, not too late so it must compete with the 2000 HP fighters).

 

[tomo pauk]

And the performance of a Hercules II would have been awful at higher altitudes no matter how good it was at low altitude.

I cannot remember saying even once that Hercule II is to be installed on a fighter for squadron service.

Great Britian is nowhere near the size of the US but a crated engine on the loading dock of the Bristol engine factor is not an engine installed in an airplane rolling out the door of an aircraft factory.

Certainly it is not. It will took a number of days, or probably a week or two between the engine delivered and aircraft actually flying with/by that engine.

So is the Spitfire I a 1934/35 design? a 1936 airplane (date of order) or a 1938 airplane (1st squadron) or a 1939 airplane (a worthwhile number of planes in service) ?

Designs moved fast back in the day. What was an epitome of fighters of 1938 was sometimes different than an epitome of fighter in 1940, and probably, if not certainly different than it was the case in 1942.
Spitfire was probably a 1936-1945 fighter - some fighters were more 'future proof' than the others.

Company XYZ may propose a modification of an existing prototype using a Hercules in order to speed things up in 1938. But the Air Ministry was already looking at planes with 2000hp engines and telling companies which engines they wanted to use. (A-S Deerhounds were not on the list)

It would not be the 1st time that fighters were re-engined, sometimes just-in-case, other times the job paid off.
How much worse would've been a Hercules-powered fighter that uses modern aerodynamics (so no worse than Spitfire) than an as-is Hurricane, Whirlwind, Defiant? Vs. an LF SpitfireV? How much a worse choice than the fighters UK was buying in the USA - both in capabilities and price in gold?
RAF was using Gladiators in 1941 for crying out loud, and UK was not sending any Spitfires abroad before ww2 was 33 months old.

 

[Shortround6]

Basically the Hercules fighter faded out after around 1938.
The Bristol 153 was from 1936 or so. It was after the Spit was designed and flew but perhaps not ordered. However in 1936 they had no idea what kind of can of worms they would be getting with the Hercules. And in 1936 I have no idea what the proposed supercharger set up was. Some of the calculations were more than bit of at the time for some designs like the Bristol 153A, a twin with four 20mm cannon using two Bristol Aquila engines, The Sleeve valve cool aid was strong in this one. Two radials that made less power than the engines in T-6 ( or even more to the point, just about the same power as a one version of the Lockheed 10 Airliner, was supposed to give fighter like performance?
There was a proposed development of the Hercules I with a two speed supercharger. It was dropped but became the bases for the Hercules III.
Much like some of Britain's aircraft companies, the engine companies could propose all sorts of things, delivering them was another story ( Many American companies were proposing all sorts of things that never showed up too, like P & W 24 cylinder sleeve valve engines).
By the time Bristol got the Hercules straightened out (unknown in 1936-37) the Merlin had passed it by. And the Merlin was about to bounced into the 2nd seat by the Vulture. (in theory/planning of the time)

RAF Gladiators had left the factory in 1938, bad example, a Hercules powered fighter that left the factory in 1938 would have been a nightmare in 1941.
Engines that frequent repair, overhaul or replacement on overseas stations are a drain on the supply chain.


If you can use 1941-42 knowledge (cowls, cooling, fuel, superchargers, etc) in 1937-38 to design the Hercules fighter you have a shot, without that knowledge it won't work.

Production totals and especially actual deliveries vs planned deliveries would be very interesting indeed. The Whole idea behind the Beaufighter II was that the Stirling had priority and yet, due to the Shorts factories being bombed actual demand for the Hercules engines was below the planned demand in late 1940.

Apparently the development of the Hercules was running a bit behind.
Several of the proposals to use it from 1936/37 say the engine would give 1500hp (altitude not given) while similar proposals give Merlin power at 1000hp or 1010hp, speeds are given at 15,000ft. Problem comes in when we consider that the Merlin would actually give just about 1000hp at 15,000ft using the early letter series Merlins. The Hercules would not become a 1500hp engine for years and the two speed supercharger was delayed.
Even when the 2 speed supercharger showed up (in the Hercules III) the engine still didn't make 1500hp at any altitude using 87 octane fuel.
1410hp at 2,750ft or 1250hp at 16,750.
Lumsden shows the Hercules VI just missed 1500hp using 87 octane fuel, 1450hp at 8,500ft using 5lbs boost. and 1265hp at 15,750ft, take-off was 1350hp.
Which Hercules engine were they planning on using in 1936/37?
Lets remember that the sleeve valve kool-aid factory was running at least 2 shifts. 1250hp Taurus engines were being proposed to counter the 1275hp Merlin R.M.2 SM engines in 1938. We know how that worked out for the Taurus.

 

[EwenS]

The very first proposals by Blackburn in Jan 1940 for what became the Firebrand, were based around the Hercules. It never got beyond paper. By Aug 1940 when the final Spec was issued the engine had become the Sabre.

 

[tomo pauk]

RAF Gladiators had left the factory in 1938, bad example, a Hercules powered fighter that left the factory in 1938 would have been a nightmare in 1941.
Engines that frequent repair, overhaul or replacement on overseas stations are a drain on the supply chain.

A Hercules-powered fighter that left the factory in 1938 would've been used during the BoB. With a surplus of modern fighters, UK can send Hurricanes overseas by 1939.

 

[Shortround6]

A Hercules-powered fighter that left the factory in 1938 would've been used during the BoB. With a surplus of modern fighters, UK can send Hurricanes overseas by 1939.

You are missing the point/s.
A fighter that left the factory with an ideal Hercules engine (or one that operated like a 1941/42 Hercules or a bit lower in power) in 1938 would have been a big advantage for the British.
A fighter that left the factory in 1938 with a Hercules engine as built in 1938/39 would have been a disaster.

Some of this is not helped by conflicting stories about different prototype/early production aircraft.
Like "During the pre-delivery trials, the first prototype R2052, powered by a pair of two-speed supercharged Hercules I-IS engines, had achieved 335 mph (539 km/h) at 16,800 ft (5,120 m) in a clean configuration.[7] The second prototype, R2053, which was furnished with Hercules I-M engines (similar to Hercules II) and was laden with operational equipment, had attained a slower speed of 309 mph at 15,000 ft. According to aviation author Philip Moyes, the performance of the second prototype was considered disappointing, particularly as the Hercules III engines of the initial production aircraft would likely provide little improvement, especially in light of additional operational equipment being installed; it was recognised that demand for the Hercules engine to power other aircraft such as the Short Stirling bomber posed a potential risk to the production rate of the Beaufighter."

Lets see, replace the two speed engines with single speed engines (which peaked at 4,000ft) and wonder why you lost 26mph in top speed?
Then think restoring the two speed supercharges won't improve things?

Short Stirling, first flown with Hercules I engines (supposedly with two speed superchargers) but but other accounts say it, the 2nd prototype and the first few production Stirling Is used the single speed Hercules IIs.

Hercules IIs were used in the Lerwick.

All the early Hercules engines used a reduction gear suitable for propellers around 13ft. Could be changed but Bristol was having trouble sorting out the two speed supercharger, and the sleeve valves. They may have been busy trying to sort out the Taurus too.

Apparently (could be wrong, welcome correction) it was not easy to change the Hercules engines. The VI, which showed up in 1941, was a high powered engine. The XI was was developed from the III was close to the VI but missed a bit. The VI was allowed to use a bit higher boost than the XI while at the same time the VI use 7.0:1 compression instead of the 6.75:1 compression the XI used (and the III). All 3 engines were rated with both 87 and 100 octane fuel.

Some people think the Centaurus was delayed (into 1942) by the need to sort out the earlier engines. Granted RR delayed work on the Griffon during this same general period.
Of Couse sorting out the sleeve valve problems did make the Centaurus program go a bit quicker once they went back to it.

The Bristol sleeve valve engines were not delivering what was promised in 1938-41. Either in power or reliability.

 

[tomo pauk]

You are missing the point/s.
A fighter that left the factory with an ideal Hercules engine (or one that operated like a 1941/42 Hercules or a bit lower in power) in 1938 would have been a big advantage for the British.
A fighter that left the factory in 1938 with a Hercules engine as built in 1938/39 would have been a disaster.

It would've been a no small feat for the series production of the Type 153 to start some time in 1938.
Before the war is declared that leaves 9-12-15-more? months to start debugging things. German onslaught on the West adds another 8 months. Start of the BoB adds another 3 months.
All of this added together means that British (Bristol, mostly) have at least 20 months to debug the 153 for the BoB, compared with Whirlwind (that won the spec) with two months.

Lets see, replace the two speed engines with single speed engines (which peaked at 4,000ft) and wonder why you lost 26mph in top speed?
Then think restoring the two speed supercharges won't improve things?

Not the 1st time the book/article writers were wrong.
It will not be the last, either.

The Bristol sleeve valve engines were not delivering what was promised in 1938-41. Either in power or reliability.

What was promised by Bristol for the Hercules?

 

[southjn1982]

Let's remember that F.18/37 specification (actually March of 1938?) led to several "designs" some by Bristol and some by others.
This was the replacement for the Hurricane and Spitfire.
View attachment 698125
Bristol and Hawker each schemed fighters using the Sabre, Vulture and Centaurus engines
Gloster schemed a twin boom pusher fighter
View attachment 698126
I am not saying that nobody looked at or sketched a Hercules powered aircraft but it would have been way down on power, It would be competing with the Merlin powered single engine fighters already in production and it offered few, if any advantages over the Merlin powered versions. FW 190 style cowls and radial installations were several years away and the drag of a 1937-38-39 Hercules would have been higher than for the Merlin. You also had to figure for the expected power of the Hercules in those years and not what they got out of it in 1941-42.

There would certainly be issues but I was thinking of it as more of a second line aircraft especially for use in the colonies and in North Africa etc where it's ruggedness is more important as well as having it as a lend lease aircraft for the Soviets as they tended to fight at lower altitudes anyway thus saving allowing for Hurricanes and Spitfires to go elsewhere. I was thinking of having a Hercules powered fighter doing the roles that fighters like the P-40 or the Buffalo did on foreign stations.

 

[southjn1982]

And the performance of a Hercules II would have been awful at higher altitudes no matter how good it was at low altitude.

It takes a while to turn on the tap. For illustration Wright built 6 R-2600 BA engines in June of 1941, 12 in July, 22 in Aug, 17 in Sept, 45 in Oct, 135 in Nov and 206 in Dec.
was the R-2600 BA a 1941 engine or a 1942 engine? Great Britian is nowhere near the size of the US but a crated engine on the loading dock of the Bristol engine factor is not an engine installed in an airplane rolling out the door of an aircraft factory.

Kind of depends on definition. Spitfire first flew March of 1935, had been in design since Nov 1934 in the form we know today. 1st operational squadron was equipped at the end of 1938. (that took a few months just for the 1st squadron) and the 1st actual production example was flown in May 1938 (24 months after contract for 310 was placed), and accepted by the RAF in Aug 1938. On the 3rd of September 1939 the Royal Air Force had 306 Spitfires, of which 187 were operating in eleven fighter squadrons.
Air Ministry was putting out the requirements for the Replacement in March, 2 month before the production plane flew.

So is the Spitfire I a 1934/35 design? a 1936 airplane (date of order) or a 1938 airplane (1st squadron) or a 1939 airplane (a worthwhile number of planes in service) ?

Company XYZ may propose a modification of an existing prototype using a Hercules in order to speed things up in 1938. But the Air Ministry was already looking at planes with 2000hp engines and telling companies which engines they wanted to use. (A-S Deerhounds were not on the list)

While the Hercules may not have been great at high altitudes a lot of the other theatres like the Eastern Front where fought at significantly lower altitudes than Western Europe, how would a Hercules powered plane have faired as a lend lease plane to the Soviets? and would that have allowed Spitfires and other planes to be sent elsewhere. I wasn't thinking of a Hercules powered plane as a 1st rate fighter but as a competent 2nd line craft for theatres like East Africa etc as a better alternative to plane like the Buffalo thus allowing for resources to be concentrated in other areas.

 

[K5083]

None of the Axis powers fielded second-rate fighters to fight the RAF overseas. The RAF did not provide adequate air support for surface forces until well into 1942. Because it was going to win the war alone, not support pongos or matelots.

These was only a short period when Hercules could be seen as a good prospect for a single-engined fighter, because there were three 2000hp class engines expected soon. Why develop a herc fighter when Hawker has two 2000hp fighters in plan?

 

[southjn1982]

None of the Axis powers fielded second-rate fighters to fight the RAF overseas. The RAF did not provide adequate air support for surface forces until well into 1942. Because it was going to win the war alone, not support pongos or matelots.

These was only a short period when Hercules could be seen as a good prospect for a single-engined fighter, because there were three 2000hp class engines expected soon. Why develop a herc fighter when Hawker has two 2000hp fighters in plan?

That's simply not true the Italians certainly used their second rate planes in East Africa mainly using CR-32s. The Germans used theirs in the Dodecanese campaign and the FW-190 was never used outside of mainland Europe, most of the Japanese Naval fighters that went against the UK in 1941-42 were A5M Claude's not A6M Zeros while the Japanese army air units in Burma were using thier second line aircraft such as the Ki 27 while most of their first rate fighters were kept for home defence as the Ki 43 was used in very limited numbers.

 

[Admiral Beez]

Best opportunity for a British-designed radial-powered single-seat, monoplane, retractable undercarriage fighter is to have it enter service before the Merlin is available for the Spitfire and Hurricane in 1936-37. Kickstarting Folland to get his ideas for the F5/34 expedited may be the best chance. Otherwise, it's the Bristol Type 133 or similar.

Bristol Type 133

Bristol Type 133 | BAE Systems | International The Bristol Type 133 after its first flight, showing open cockpit and full span ailerons/flaps. A side view of the Type 133 R-10 fitted with an enclosed cockpit canopy. The Bristol Type 133 looked elegant in flight, like a precursor of the Vought...

ww2aircraft.net

 

[Shortround6]

Best opportunity for a British-designed radial-powered single-seat, monoplane, retractable undercarriage fighter is to have it enter service before the Merlin is available for the Spitfire and Hurricane in 1936. Kickstarting Folland to get his F5/34 expedited may be the best chance. Otherwise, it's the Bristol Type 133 or similar.

Bristol Type 133

Bristol Type 133 | BAE Systems | International The Bristol Type 133 after its first flight, showing open cockpit and full span ailerons/flaps. A side view of the Type 133 R-10 fitted with an enclosed cockpit canopy. The Bristol Type 133 looked elegant in flight, like a precursor of the Vought...

ww2aircraft.net

We have been over this a crap load of times.
Yes you can get a radial engine fighter into production before 1936-37.
1. It won't be a Hercules powered airplane.
2. It will run into a Stone wall with lack of new engines in just a few years
3. It won't be very good in 1939-40, can we say "waste of money"

 

[EwenS]

.....and the FW-190 was never used outside of mainland Europe.......

Not true. They were used in North Africa in 1942/43

MEDITERRANEAN MAELSTROM

Morten Jessen and Andrew Arthy describe how Fw 190 operations...

www.key.aero

 

[southjn1982]

We have been over this a crap load of times.
Yes you can get a radial engine fighter into production before 1936-37.
1. It won't be a Hercules powered airplane.
2. It will run into a Stone wall with lack of new engines in just a few years
3. It won't be very good in 1939-40, can we say "waste of money"

not necessarily in July 1939 the Poles ordered the Hercules for the PZL.53 obviously with the war starting only a couple of months afterwards the Plane never went into production but if the order had been made a couple of months earlier in the same order the Poles also planned ordered a modification to the Taurus that pushed it to 1,145hp for the PZL 50b although it wasn't due for delivery until October 1939 and when the war started only a handful (1 completed + 6 almost finished) of Pre-production PLZ 50a's (using Bristol Mercury VII) had been completed . If the war had broken out in September 1940 not 39 the Poles expected to have 300 modern fighters mainly PZL 50bs and PZL 53's if these fighters had seen service it is likely that more attention would have been paid by the British.