Full-radial engine FAA?

[tomo pauk]

Hello, people,

The UK's Fleet Air Arm was in several things different than USN or IJN 'air forces'. One of those was the wide use of V-12, liquid cooled engines, during the ww2, plus before and after that. Bristol company have had in production some useful radial engines, but the RR Merlin, even Griffon, were a familiar thing under the cowlings as the war moved on.
So, my questions: how god would be the FAA advised to go all-radial, forgetting the Merlin and Griffon? The engines at start of ww2 were, historically, Perseus, Mercury and Taurus, so Bristol could offer Hercules for 1940 and beyond? Could Australia jump on this band-wagon, producing British-designed airframe with Twin Wasp and, later, another airframe with Hercules? Canada can maybe use plentiful Cyclones and Twin Wasps for their license-produced airframes?

 

[Shortround6]

"The engines at start of ww2 were, historically, Perseus, Mercury and Taurus, so Bristol could offer Hercules for 1940 and beyond?"

They could offer it.

the Perseus, Mercury and Taurus all overlap and one doesn't really offer much more than another being almost identical in displacement. Nothing over 1100hp is possible including the larger Pegasus. Hercules is running behind schedule in production in 1940. It also never offers a high altitude version. Question starts to become which version of which engine (Hercules, Merlin, Griffon) became available when. Historically the Hercules didn't get ejector exhaust until the 100 series. Merlin was offering 1275hp at 9lbs boost on the VIII and 1360hp at 12 lbs on the Merlin 30 so the early 1375-1400hp Hercules doesn't really offer much.

 

[m37b1]

Wasn't the BSFC superior on the Merlin vs the radials? Impact on range?

 

[tomo pauk]

Guess I might check out the consumption in the Beaufighter manual, and then compare it with different appropriate Merlins.

the Perseus, Mercury and Taurus all overlap and one doesn't really offer much more than another being almost identical in displacement. Nothing over 1100hp is possible including the larger Pegasus.

Doh, I've forgot the workhorse

Hercules is running behind schedule in production in 1940. It also never offers a high altitude version.

Guess the (non)availability of the Hercules is a far bigger hurdle than couple of dozen HP more or less. The Merlins in FAA were mostly of the low-alt versions, apart from Merlin 45s and alike, used on Seafires.

Question starts to become which version of which engine (Hercules, Merlin, Griffon) became available when. Historically the Hercules didn't get ejector exhaust until the 100 series. Merlin was offering 1275hp at 9lbs boost on the VIII and 1360hp at 12 lbs on the Merlin 30 so the early 1375-1400hp Hercules doesn't really offer much.

Those power values are for sea level (Mk.VIII), or 6000 ft (Mk. 30). The early single speed Hercules is at 1380 HP at SL and for take off, at 6000 ft it was just 1200 HP. In between the Merlin VIII and 30? Two-speed Hercules III is at 1425 HP at 1500 ft, but also 1200 HP at 15000 ft.
The Hercules VI (1941?) was making 1600-1700+ on 100/130 oct down low, and ~1550 HP at 15500 ft, according to Lumsden.

 

[Koopernic]

Hello, people,

SNIP

Could Australia jump on this band-wagon, producing British-designed airframe with Twin Wasp and, later, another airframe with Hercules? Canada can maybe use plentiful Cyclones and Twin Wasps for their license-produced airframes?

Australia started to develop an air industry in the 1930's under the foresight of Lawrence Wacket. They produced Pratt Whitney R-1830 Twin Wasp hear in auburn where I work (now full of Mosques and Fast Food Burger Joints). Wacket, an engineering hero of Australia had tried to develop an aviation industry in Australia, however in 1931 his RAAF experimental station was shutdown under pressure from British manufacturers due to protectionist sentiment. Wackett was latter back in 1936 and lead the development of aviation in Australia using American designs such as the NAA-16 trainer and Australia developed a fairly effective fighter, the CAC Boomerang built around the R1830. Like All Australian designs of the era it featured impressive range.

The final nail in the coffin for use of anything British in terms of engines was when Britain reneged on allowing license production of its water cooled fighter engines. When Darwin was bombed by the Japanese it was lucky American P-40 on a staging mission were able to provide some protection.

From then on, also in part due to Churchill's "Germany first" emphasis. Australia started to look to the United States for allegiance and advanced defense technology. We don't use enough in my opinion still to often using second rate European equipment. I do have to add that Britain made a great sacrifice in sending Prince of Wales and Repulse without a carrier to Singapore to defend against Japanese advance but it was of course ineffective considering the lack of a carrier. To an extent Australia is to blame, in the 1930's defense expenditure dropped to 1% while Britain was at around 4% at the time but certainly technical help from the UK did not come when it was needed because of sustained protectionist sentiment within British aviation industry.

 

[nuuumannn]

The engines at start of ww2 were, historically, Perseus, Mercury and Taurus, so Bristol could offer Hercules for 1940 and beyond?

The FAA was an all radial engine equipped aircraft force aboard its carriers at the outbreak of WW2; the Skua fleet fighter, dive bomber, the Swordfish torpedo spotter reconnaissance machine and the Sea Gladiator fighter. Aboard RN vessels was the Walrus, also with a radial. Although there were a few Fairey IIIFs and previously there had been hawker Ospreys and Nimrods, these were largely in a training role by the outbreak of war. The first of the FAA's Grumman Martlets gave the FAA a good carrier based fighter with a round engine, but the Fulmar turned back to an in-line. The spec intended on being fulfilled by the Firebrand, N.8/39 and N.9/39 included a couple of radial options, the Gloster variant included, a Hercules HE.6SM, but predominant designs were in lines, either Merlins, Griffons or Sabres, but Fairey also offered the RR Boreas or Exe. It seems that the bigger outputs of British in-lines meant they were the larger consideration for the FAA's requirements of the british industry, but with Lend lease, American equipment was available in large numbers, later F4Fs, F6Fs, TBFs and F4Us, of course.

 

[tomo pauk]

Anyone wants to make a stab how a Hercules-powered fighter would've fared, either built in lieu of Fulmar (with Hercules II/III/IV/VI) or as a single seater (along the lines of 'radial-Hurricane' or 'radial-Seafire', or something brand new)?

 

[merlin]

Anyone wants to make a stab how a Hercules-powered fighter would've fared, either built in lieu of Fulmar (with Hercules II/III/IV/VI) or as a single seater (along the lines of 'radial-Hurricane' or 'radial-Seafire', or something brand new)?

Well, to Spec. F.37/35 for the 4 x 20mm cannon fighter, the Air Ministry wanted prototypes: two Westland P.9 (became Whirlwind), a Supermarine 313, and two Boulton-Paul P.88s - 'A' Hercules 'B' Vulture. The 'A' was estimate to have a max speed of 337 mph at 15,000 ft., RoC of 3,500 at 5,000 ft.

So, assuming the (B-P) prototypes are built, perhaps the 'B' crashes due to problems with the engine!! The A's test flight is not brilliant the engine is not as powerful as expected, nevertheless, it handles well, the RAF is interested but not enough with the early Hercules, and will wait for a better engine. The FAA - get to hear about it and aren't that fussy about the speed, more impressed with the firepower it would give them, and orders a batch.

Hence 'my' radial FAA is: Walrus, Swordfish, Skua is a Mk II feasible with a better engine (?), but no Rocs, Gloster Sea Gladiator, Gloster f.5/34, B-P Sea Dante (I've used the name before) - as the engine grows in power so does its versatility - carrying bombs, Barracuda powered by first the Hercules and then a Centaurus. Plus of course the US aircraft - Martlet, Hellcat, Corsair Avenger.

 

[Glider]

The advantages of having a Hercules fighter probable has more to do with safety than performance. I am sure the performance would be similar. The Lancaster and the Beaufighter had the same airframe and the two engines. IIRC the performance was very similar with the Hercules having an advantage at lower altitude which isn't really an issue for carrier fighters and the Merlin the advantage at height.
The advantage would be the ability to design an aircraft such as the Hellcat with a short nose, sitting the pilot higher up with a much improved view forward for landing and getting the correct lead on an opponent who may well be trying to evade.
The radial engine is also more resistant to damage. There are many examples of radial engine aircraft making it back to base with considerable damage to the engine where an inline would have given up the ghost long before.

For an early war naval fighter the Gloster F5/34 would be an excellent start. It would need a more powerful engine to allow for the extra weight but as a start you could do a lot worse.

 

[Shortround6]

The radial engine is also more resistant to damage. There are many examples of radial engine aircraft making it back to base with considerable damage to the engine where an inline would have given up the ghost long before.

Not all radials showed the same resistance to damage. Granted there is no liquid cooling system but some radials didn't show the same resistance to actual engine damage as the R-2800 did and indeed at least one French radial showed a rather alarming tendency to shed it's propeller without any help from an enemy.

 

[RCAFson]

The Hercules, in 1939-41 didn't offer a sufficiently good power to weight ratio to make it a viable engine for a SS naval fighter, IMHO.

 

[nuuumannn]

The Hercules, in 1939-41 didn't offer a sufficiently good power to weight ratio to make it a viable engine for a SS naval fighter

Make it a twin, then. Tomo, you're gonna like this, being into leftfield ideas. How about a naval Beaufighter? Folding wings, strengthened rear fuse to take a hook, but reduced armament in the wings for weight saving?

Here is a recollection by a former Beaufighter WOp/AG from Canada, Andy Fraser, who trained in Coastal Command in 1945 in the Firth of Forth area near Edinburgh:

"Another way to beat boredom was to fly down the Forth and make a pass at RN aircraft carriers anchored there [normally near the naval base at Rosyth]. We would pretend that we were going to land on and this bothered them – they would give us a red Aldis light and then red Very lights – but fortunately no live firing. We also beat up convoys off the coast – a very hazardous trick."

"The Beaufighter from a NavW point of view was a great aircraft. We had lots of room, a good nav table, good Gee box location, and an excellent WT Marconi radio. We had a slip stream operated hatch, a nice bubble coup top and a Vickers K 30 calibre machine gun (we called it a scatter gun) and it usually whopped the Nav on the head in violent turns.

From a pilot's point of view the Beau had plenty of power, but had a few quirks that you had to watch for. It had a habit of the plugs on the Bristol Hercules engines oiling up if you had to wait at the end of the runway. Then when you opened up there would be a bang and you would be taking off across the runway."

 

[tomo pauk]

I'd rather have that Gloster twin

The Hercules, in 1939-41 didn't offer a sufficiently good power to weight ratio to make it a viable engine for a SS naval fighter, IMHO.

The Merlin VIII was not offering power, yet it was used on a big two-seater. The take off and SL power for the Merlin VIII and X was similar on 100 oct fuel (1275 HP for the Mk. VIII).

 

[RCAFson]

I'd rather have that Gloster twin



The Merlin VIII was not offering power, yet it was used on a big two-seater. The take off and SL power for the Merlin VIII and X was similar on 100 oct fuel (1275 HP for the Mk. VIII).

]

The Mk VIII was offering 1275-1300hp TO with a 1420lb dry weight which was an excellent figure for 1940. By Dec 1941 the Merlin 30 was rated at 16lb boost for about 1540hp at ~4000ft with the same weight as the Mk VIII. Lumsden's 1993 British Piston Aero-engines gives the dry weight of the Hercules I as 1845lb but apparently this was revised to 1925 lb in 2003, so I have to wonder about the accuracy of the pre-war figures from Flight magazine. In any event there were no SS fighters designed around the Hercules and only the Hurricane was ever modded to used the Hercules, AFAIK

 

[merlin]

....... In any event there were no SS fighters designed around the Hercules and only the Hurricane was ever modded to used the Hercules, AFAIK

I think Tony Butler in BSP would disagree with you, he refers two to spec .F.37/35 - as I previously mentioned the:

- Boulton-Paul P.88a span 39' 6" length 32' 8" w/area 260 sq. ft., max weight 6,573 lbsest max speed at 15,000' 337 mph

for comparison the P.88b powered by a Vulture span 44' length 36' 3" w/area 320 sq. ft. max weight 8,100 lbs est max speed 358 mph at 15,000'

The other one was the Bristol 153 span 37' length 25' 3" w/area 204 sq. ft. weight n/a est max speed 357mph at 15,000' (it was derived from the Type 151 high-speed research aircraft, and due to the thin wings the guns were to in underwing fairings.

 

[fastmongrel]

What If Hurricane with an Ash82 radial. Looks pretty good.

 

[tomo pauk]

The Mk VIII was offering 1275-1300hp TO with a 1420lb dry weight which was an excellent figure for 1940.

It is 1275 HP for take off It is also ~1120 HP at 5000 ft, vs. 1200-1300 HP vs. Hercules IV or II.

Dec 1941 the Merlin 30 was rated at 16lb boost for about 1540hp at ~4000ft with the same weight as the Mk VIII.

By late 1941, the Hercules VI is available, that offers 1450-1750 HP at low altitudes.

Lumsden's 1993 British Piston Aero-engines gives the dry weight of the Hercules I as 1845lb but apparently this was revised to 1925 lb in 2003, so I have to wonder about the accuracy of the pre-war figures from Flight magazine.

The single-speed Hercules II and IV should be weighting a bit lower than 2-speed engines, let alone the later, improved and strengthened versions. For the V-12s, we also need to add the weight of coling system, ie. circa 300 lbs.

In any event there were no SS fighters designed around the Hercules and only the Hurricane was ever modded to used the Hercules, AFAIK

This thread is more about exploring the paths that were realistically possible, but not taken
The FAA saw fit to order a twin seat fighter with ample fuel and ammo, designed around 1000-1300 HP engine; the Hercules in a such and airframe should give decent performance, let alone in signle seater.

 

[tomo pauk]

What If Hurricane with an Ash82 radial. Looks pretty good.

This one, down, was captioned as Centaurus-powered Hurricane project, though that engine would've been quite a beast to be grafted to the Hurri. The one with Hercules should've looked similar?

added: if you think I'm a what-if wacko, check out this:

http://www.sas1946.com/main/index.php?topic=15512.0

 

[RCAFson]

I think Tony Butler in BSP would disagree with you, he refers two to spec .F.37/35 - as I previously mentioned the:

- Boulton-Paul P.88a span 39' 6" length 32' 8" w/area 260 sq. ft., max weight 6,573 lbsest max speed at 15,000' 337 mph

for comparison the P.88b powered by a Vulture span 44' length 36' 3" w/area 320 sq. ft. max weight 8,100 lbs est max speed 358 mph at 15,000'

The other one was the Bristol 153 span 37' length 25' 3" w/area 204 sq. ft. weight n/a est max speed 357mph at 15,000' (it was derived from the Type 151 high-speed research aircraft, and due to the thin wings the guns were to in underwing fairings.

Sorry, I should have stated "designed and built" around the Hercules so that we would have a look at actual versus claimed performance. There were several proposals for two seat naval fighters to spec (N.8/39) and two seat (N.9/39) turret fighters, issued June 21 1939, which would have used the Hercules namely the Bristol and Gloster N.8/39 and N.9/39 but none advanced beyond initial proposals. The big problem here is that we don't get a service aircraft until about mid 1942. Another spec, NAD.925/39 was issued later in 1939 for a high performance SS and TS naval fighter but none proposed using the Hercules, although one, which became the Blackburn Firebrand proposed using the Centaurus. Both the Firefly and Firebrand appeared much later than hoped for, even though the spec ( NAD.925/39) was issued in 1939.

 

[RCAFson]

It is 1275 HP for take off It is also ~1120 HP at 5000 ft, vs. 1200-1300 HP vs. Hercules IV or II.





By late 1941, the Hercules VI is available, that offers 1450-1750 HP at low altitudes.



The single-speed Hercules II and IV should be weighting a bit lower than 2-speed engines, let alone the later, improved and strengthened versions. For the V-12s, we also need to add the weight of coling system, ie. circa 300 lbs.



This thread is more about exploring the paths that were realistically possible, but not taken
The FAA saw fit to order a twin seat fighter with ample fuel and ammo, designed around 1000-1300 HP engine; the Hercules in a such and airframe should give decent performance, let alone in signle seater.

The problem with the Hercules is that is was not ready for service use until 39/40 (Hercules I didn't enter production until 1939) whereas the Merlin II/III is in service use from ~1937. This means that for the FAA to have a Hercules power fighter, it must be designed around an engine that existed only as a prototype (so the spec was always changing) and was giving rather unimpressive output compared to the much lighter Merlin and the R-1830. According to Lumsden, the Hercules II dry weight was 1929lb (wikipedia via Lumsden 2003 and it also gives much lower output) and gave only 1375hp at TO and 1375hp at 5000ft. Compare that to an R-1830 with a dry weight of 1250lb which gave 1200hp at TO and at ~2000ft. The Hercules III only gained 25hp by using 100 octane fuel, according to Lumsden.