Bistol Type 153 wins the F.37/35, no W. Whirlwind

[nuuumannn]

Why the Brits thought that sleeve valves was the right path IDK.

I'd hate to say the Old Boy network, but it's as likely as anything. Bristol was a big company with a good reputation during the 20s, coming out of the Great War having supplied one of Britain's most reliable aircraft, the F.2b, which continued production and reconditioning of existing examples for continued service and export after the war ended. Bristol built engines proved reliable and able to meet requirements in 1920s aircraft, as they were widely used and exported in that decade and the 30s, the Jupiter and Mercury being built under licence abroad. Aircraft wise, Bristol, like every other manufacturer entered designs into almost every specification imaginable to get work, and sometimes their designs registered, such as the Bulldog. The company had a reputation for reliability and it also had money, which helped. If the engine company promised an engine could do such and such, there was a tendency to believe it, why wouldn't those concerned not believe the claims about sleeve-valves? After all, Fedden had a good reputation and produced good reliable designs in the past.

In peacetime the formidable challenges of building these engines were not as readily apparent as they became once the pressures and expediencies of wartime mass-production and high sortie rates by individual aircraft started to happen, so the complexities of the sleeve valve were easily absorbed into the sedate day-to-day operation of a between-the-wars Britain. Once the pressure cooker gets turned up in the late 1930s, the cracks - literally - begin to show.

 

[Admiral Beez]

Bristol made too many engines, Look at P&W, pretty much everything is a variant of the Wasp. Of course each Wasp was different from the others, but the core tech was foundational. Bristol should have gone from Mercury poppet valves to Pegasus to twin row Pegasus. Full stop.

The Pegasus seems to be a fine, easy to maintain engine and a good foundation for a twin row 18 cylinder power-plant with conventional ohv operation.

 

[Shortround6]

Don't believe everything you read, especially advertisements.
At least 5 grease fittings on each cylinder head.
Also look up Alfa Romero 135 engine.
An 18 cylinder engine using Bistol Mercury cylinders.

 

[don4331]

In '27, when Fedden started his work on sleeve valves, they appeared to be thee answer:
They allowed higher volumetric efficiency, allowed higher operating speeds and didn't have the issues of poppet valve with either wear (primarily valve seats, but also cams and guides), or being hot spots (lower compression. lower boost or higher octane)

And today, we laugh about the short service time between top end overhauls (British Civil Type test requirement was 50 hours)m but that was what poppet valve engines were working with. And no one's crystal ball told them that the solution (Stellite valve seats and sodium filled valves) was just round the corner. And electric arc furnaces would allow steel to be rid (dramatically reduced) of impurities, so broken valve springs became a rarity.

And by '32 when the Perseus runs, Bristol has spent a trainload of money making it work. They, of course, want to get their money out of their development. (Almost bankrupt the company)

And it is never as easy as just tacking on another row and the engine runs perfect with double the power. Even look at Rolls Royce - the Peregrine should just be an upgraded Kestrel, yet it took 6 months from running prototype to have half dozen (2 Whirlwind prototypes and Gloster's); and then almost 18 months before they were able to provide production engines. Westland gets a lot of blame for Whirlwind being late, but there were air frames waiting engines (and landing gear) at end of assembly line.

Aside: Messerschmitt had same issue with Bf.109E's awaiting DB601s but production caught up just in time (doubly good ?bad for Allies? as Jumo had shutdown the 210 line).

The only other company that I can think of that bet the farm as dramatically would be GE with the turbocharger (and GE had a lot of other business to sustain the company). And even they struggled well after war - R-4360s on B-50s had all sort of turbo issue, to the point where P&W figured they should have built the B-44 (same plane but 2 stage mechanical supercharger. And look at how many WWII airplanes still use their original turbos...

 

[Admiral Beez]

And today, we laugh about the short service time between top end overhauls but that was what poppet valve engines were working with. And no one's crystal ball told them that the solution (Stellite valve seats and sodium filled valves) was just round the corner.

Excellent points. But how did everyone else making air cooled radials between the wars address these challenges? Were the radial air cooled engine designers at P&W, Wright, BMW, Shvetsov, Nakajima, Mitsubishi, Gnome-Rhône, Piaggio and Fiat just later to the game? How did Armstrong-Siddeley meet these issues with their radials?

 

[Jabberwocky]

Bristol wins and what happens?

The Type 153 is going to be a little late to the party for 1939 - but probably not as late as the Whirlwind. Potentially, Fighter Command ends up with three major single seat fighters for the battles of 1940, instead of two and a couple of also rans.

If we assume the same historical pace with the Air Ministry as for the Whirlwind, Bristol gets a contract for a pair of prototypes in February 1937. The first of these is expected to be assembled and ready for testing by around the middle of 1938.

Westland didn't get the Whirlwind into the air until October 1938, but they were held up by some design and issues with deliveries of the Kestrel engine and landing gear. Then things are compounded by the decision to up-engine to Peregrine.

However, by early 1939 the Air Ministry is happy enough with the performance to order 200 from Westland and then 800 from Castle Bromwich. This is cut pretty rapidly, with the Castle Bromwich order being transferred to Spitfires by March 1939 and Westland at Yeovil also tasked with producing Spitfires.

The Type 153 is a simpler aircraft and Bristol is a larger firm with more resources. They Type 153 is also a refinement of an existing experimental design. I don't think its unreasonable to expect that the Type 153 could be three or four months ahead of the Whirlwind in getting the initial prototype in the air (say June or July 1939). With no re-engining needed and a fundamentally more conservative design, the Type 153 also probably passes through development and flight testing a little more quickly/easily. Maybe another three to six months shaved off the historical timeline compared to the Whirlwind?

If the aircraft is looking promising performance wise (and with a 1300hp+ Hercules by 1938, it probably is going to) and is not substantially more expensive than the Hurricane and Spitfire, I can see the Air Ministry placing large orders for Type 153s in 1938 and then sticking with them.

So, instead of Whirlwind service entry around June 1940, the Type 153 could maybe enter service six to nine months earlier? Say initial squadron service in the last quarter of 1939, just in time for the panic to set in following the fall of Poland?

Then its a matter of how many Bristol could produce and whether making the Type 153 is going to displace production of large numbers of other Hurricanes and Spitfires. Or whether the Air Ministry thinks that something else - looking at you Boulton Paul Defiant - gets its production cut back.

Potentially, the RAF could put a couple of squadrons with Type 153s into service per quarter. Maybe 4 or 5 in service by the time of the invasion of France?

 

[Admiral Beez]

Bristol wins and what happens? Bristol gets a contract for a pair of prototypes in February 1937. The first of these is expected to be assembled and ready for testing by around the middle of 1938.

One of the smart things Britain did was to have a few as possible different single-seat, single-engine, monoplane fighters, especially in the important rearmament years of 1936-40. Spitfire and Hurricane, that's it. Meanwhile, the French had six entirely distinct single-seat, single-engine, monoplane fighter programs in production between 1936 to 1940.

1. Bloch MB.150. Specified 1934. First flight 1937. Introduced 1939.
2. Morane-Saulnier M.S.406. Specified 1934. (same as the MB.150). First flight 1938. Introduced 1938.
3. Arsenal VG-33. Specified 1936. First flight 1939. Introduced 1940.
4. Dewoitine D.520. Specified 1936 (same as the VG-33). First flight 1938. Introduced 1940.
5. Caudron C.714. Specified 1936 (same as VG-33). First flight 1936. Introduced 1940.
6. Koolhoven F.K.58. Specified 1937. Ordered from Dutch firm. First flight 1938. Introduced 1940.

These came in three batches, Specifications of 1934, 1936 and 1937.

I do not see the benefit of Britain following France's example and pursuing a proliferation of different aircraft for the same role, at least not until after 1941 when resources allowed for additional single-engine, single-seat fighter programs like the Typhoon, Tempest and Martin-Bakers, Firebrand, etc. So, IMO the only way the Bristol Type 153 is produced before 1939 is because either the Hurricane or Spitfire is not.

With its potential for reducing the strain on Merlin production, I'd be okay doing without the Hurricane and making the Type 153 instead as long as developmental/production delays and maintenance issues with the Hercules didn't reduce the otherwise large number of Hurricanes that were available for the BoB.

 

[nuuumannn]

Looking at this from a performance and adaptability perspective, I don't think the Bristol is going to offer the RAF much more than what the Hurricane did, to be frank. It's certainly not going to be able to be up-engined to something more powerful, such as a Centaurus that offers a significant upgrade to its performance unless major redesign is undertaken. I can see it having a short service career because it's highly doubtful that it could match the Fw 190 once that enters the combat arena in 1941. Like the Hurricane I the type would no longer be fit as a frontline fighter following the Battle of Britain and the appearance of the Bf 109F and with the availability and large production contracts the Hurricane II was issued, the RAF has its ground attack fighter available already.

 

[Shortround6]

If the aircraft is looking promising performance wise (and with a 1300hp+ Hercules by 1938, it probably is going to) and is not substantially more expensive than the Hurricane and Spitfire, I can see the Air Ministry placing large orders for Type 153s in 1938 and then sticking with them.

The extra power probably will not translate into extra performance in real life.
The P-40B was about 22mph faster at 15,000ft than a P-36A if both were using 600hp.
The P-40B was about 25mph faster at 15,000ft if the P-40B was using 720hp and the P-36A was using 750hp.
and so on.
The P-40B was as fast using 600hp as a P-36A was using 750hp.
Radial engine installations in 1936-41 usually sucked. The extra 30% power the Hercules offered over the Merlin is going to get sucked up in drag pretty quick. Throw that in with the Hercules having several thousand feet less FTH and the performance in the upper teens and twenties really disappears.

Most people figure that the sleeve valve engines were at least twice as expensive per hp as the poppet valve engines. These are always estimates/guesstimates but the substantial more expensive is in question.
Then there is the whole get the Hercules into production in 1940 thing. The Hercules was in production in 1940, barely, when compared to the Merlin. 300-400 Hercules engines in all of 1940?? Production was ramping up in 1940 and thousands were made in 1941 but that is a little late for this scenario.

. Meanwhile, the French had six entirely distinct single-seat, single-engine, monoplane fighter programs in production between 1936 to 1940.

1. Bloch MB.150. Specified 1934. First flight 1937. Introduced 1939.
2. Morane-Saulnier M.S.406. Specified 1934. (same as the MB.150). First flight 1938. Introduced 1938.
3. Arsenal VG-33. Specified 1936. First flight 1939. Introduced 1940.
4. Dewoitine D.520. Specified 1936 (same as the VG-33). First flight 1938. Introduced 1940.
5. Caudron C.714. Specified 1936 (same as VG-33). First flight 1936. Introduced 1940.
6. Koolhoven F.K.58. Specified 1937. Ordered from Dutch firm. First flight 1938. Introduced 1940.

you are a bit off.

Yes there were 6, or more, programs in production but the years and intentions were bit chaotic.
The French could not get the number of fighters they wanted built in the production facilities they had and they had delayed development/production so much that the early version/s had become obsolete.
# 5 & 6 on list were desperation moves/orders to try to get more planes when the production orders for #1-4 were delayed.

What is off the List is the Curtiss Hawk 75 which was first ordered 1938 with more orders placed as time went on. The Hawk 75 saw more service than #s 3, 5, and 6 did put together.

You had 3 different engines (the Caudron C.714 with it's Renault engine should never have been a 1st line contender) and you had different types of construction which also means that not every fighter could have been plugged into a different factories manufacturing setup.


The British could have supported a 3 rd fighter type. They were certainly doing plenty of subcontracting between factories as it was.
Unfortunately the British were doing a lot of subcontracting and shadow plant production in the Blenheim bomber program and not a fighter program.

The British certainly used up a lot of production capacity in 1940 on aircraft that contributed little or nothing to the British war effort.

 

[tomo pauk]

Most people figure that the sleeve valve engines were at least twice as expensive per hp as the poppet valve engines. These are always estimates/guesstimates but the substantial more expensive is in question.
Then there is the whole get the Hercules into production in 1940 thing. The Hercules was in production in 1940, barely, when compared to the Merlin. 300-400 Hercules engines in all of 1940?? Production was ramping up in 1940 and thousands were made in 1941 but that is a little late for this scenario.

It is not late. Ww2 is just about to start, there is a lot of time for many Type 153s to be made.
In this scenario, Peregrine is not needed, allowing RR to make more Merlins. I'd say that one Hercules is cheaper than two Peregrines.

 

[Admiral Beez]

Looking at this from a performance and adaptability perspective, I don't think the Bristol is going to offer the RAF much more than what the Hurricane did, to be frank. It's certainly not going to be able to be up-engined to something more powerful, such as a Centaurus that offers a significant upgrade to its performance unless major redesign is undertaken. I can see it having a short service career because it's highly doubtful that it could match the Fw 190 once that enters the combat arena in 1941.

I agree. I think the Type 153 will be akin to the Curtiss P-36. Not bad at war's onset but soon left behind. It's a shame Bristol (or Armstrong-Siddeley) didn't just focus on a twin row eighteen cylinder poppet valve engine. It could have been in service much sooner, likely leading eventually to a larger version of the size of the Pratt & Whitney R-2800 Double Wasp.

 

[don4331]

It is not late. Ww2 is just about to start, there is a lot of time for many Type 153s to be made.
In this scenario, Peregrine is not needed, allowing RR to make more Merlins. I'd say that one Hercules is cheaper than two Peregrines.

1st I have a hard time seeing the Type 153 winning the contest - Whirlwind is up and flying in '38, while Bristol's entry is waiting until '39 for engines. Even then given the real life numbers for Spitfire & P-40 versus engine power versus P-36 and its power, and factoring in the additional drag of the under-wing pods, the Bristol fighter is going to have a hard time breaking 300mph, let alone being faster than Supermarine's fighter at low altitude.

Additionally, the HS.404 cannons, especially in their early versions didn't like wing mounts (they wanted to be bolt to the heavy mass of an engine). And the pod isn't even mounted to the structure of the wing, but tacked on below - a recipe for misfires, jams and dispersed firing even when working.

Note 1: While Bristol has more resources than Westland, it is working on the manufacture of 1 existing engine (Mercury), manufacture and development of 2 (Perseus and Pegasus), getting 2 to manufacture (Taurus and Hercules) and long term development of another (Centaurus) - which is about double any of the other manufacturers (and I'm not counting the Aquila). And they are working on manufacture of at least 2 existing air frames (Beaufort and Blenheim/Beaufighter). To say the company was stretched thin is an understatement.

Note 2: One of the things Westland (and RAF) learned with the Whirlwind - it took >2 years from time production commenced until a new aircraft was ready for squadron service (training o factory staff, building squadron numbers, training of pilots, training of ground crew, etc). So, Bristol (or Westland) needs their airplanes in production in by mid-38 at latest to be available for BoB; early '38 for BoF.

Aside: One of things I learned today - Whirlwind needed Fowler flaps down at least one notch when climbing/high speed or engines overheated - WEW Petter's linking of flaps and cooling mess again. Which probably didn't help Westland's fighter's performance numbers.

Given Hercules needed copper junk heads to provide adequate cooling, and copper is 3X more expensive than aluminium, and adding in the higher cost of sleeve valves, 2 Peregrines cost was probably very similarly to one Bristol radial.

 

[don4331]

Excellent points. But how did everyone else making air cooled radials between the wars address these challenges? Were the radial air cooled engine designers at P&W, Wright, BMW, Shvetsov, Nakajima, Mitsubishi, Gnome-Rhône, Piaggio and Fiat just later to the game? How did Armstrong-Siddeley meet these issues with their radials?

Just about all of those engines are a successor to either the Wright Whirlwind or Bristol Jupiter (Or some of both). So, solving the issues for those 2, solved it for the others.

And forged heads, with machined fins, sodium valves and Stellite valve seats which were introduced over the 8 years which Bristol fought with sleeve valves meant that by time Fedden had sleeve valves working, poppet valves had improved to the point they were equal on performance and 1/2 the cost.

 

[nuuumannn]

1st I have a hard time seeing the Type 153 winning the contest

Yup, this what-if is a little skewed as the Bristol was not even one of the favoured entries to the specification. The Westland P.9 won, but apparently the Supermarine entry was preferred by a few of those evaluating the tenders. It came second, with the Boulton Paul effort coming third.

 

[wuzak]

It just takes one

View attachment 658218

Says the guy that, in the second post in the thread, redirected the topic to FAA carrier fighters!

Bristol knows it's working on the Hercules, so make a speculative fighter for the FAA designed "for-but-without" the Hercules as the intended powerplant when its available. By 1937 single-seat carrier fighters are the now and future - the A5M, F3F and Dewoitine D.373 having entered fleet service in 1936, with the F4F and Sea Gladiator first flying the following year. There's enough to go on for a successful firm like Bristol to invest in their own all-metal, monoplane carrier fighter powered by the Taurus but ready for the Hercules. It will need more fuel and substance than the diminutive 146 above. If that's an early Type 153 that's good.

 

[Jabberwocky]

The extra power probably will not translate into extra performance in real life.
The P-40B was about 22mph faster at 15,000ft than a P-36A if both were using 600hp.
The P-40B was about 25mph faster at 15,000ft if the P-40B was using 720hp and the P-36A was using 750hp.
and so on.
The P-40B was as fast using 600hp as a P-36A was using 750hp.
Radial engine installations in 1936-41 usually sucked. The extra 30% power the Hercules offered over the Merlin is going to get sucked up in drag pretty quick. Throw that in with the Hercules having several thousand feet less FTH and the performance in the upper teens and twenties really disappears.

I'm not expecting Spitfire or 109E-like performance, more somewhere around the performance of the Hurricane I.

Looking at radial powered monoplane single engine fighters of the pre-war era, performance varies from about 290 mph at the low end to 335-340 mph at the top end for some experimental/just entering service types.

Most people figure that the sleeve valve engines were at least twice as expensive per hp as the poppet valve engines. These are always estimates/guesstimates but the substantial more expensive is in question.

I'm sure there's probably some costing - or at least manhour estimates - for British engines buried in MAP or Air Ministry records, but all I can ever find are a few vague 'The Merlin cost X in Y year' statements out of general histories.

Then there is the whole get the Hercules into production in 1940 thing. The Hercules was in production in 1940, barely, when compared to the Merlin. 300-400 Hercules engines in all of 1940?? Production was ramping up in 1940 and thousands were made in 1941 but that is a little late for this scenario.

Thanks. I was wondering about Hercules production. I had no idea.
All I could find is that initial flight testing at 1390 hp was completed during 1938.

 

[Admiral Beez]

Says the guy that, in the second post in the thread, redirected the topic to FAA carrier fighters!

Well yes, I refuse to be a contrarian so I usually try to find a way to make most ideas at least plausible. To that end I think Bristol's best hope for getting a single seat, single engine, monoplane, radial powered fighter into service is through the FAA. I am surprised the Gloster F5/34 wasn't thus grabbed. Bristol needs to make a Fulmar killer, so that the Sea Gladiator is replaced by the Type 153 (or whatever) well before the Fulmar idea comes about.

 

[wuzak]

Well yes, I refuse to be a contrarian so I usually try to find a way to make most ideas at least plausible. To that end I think Bristol's best hope for getting a single seat, single engine, monoplane, radial powered fighter into service is through the FAA. I am surprised the Gloster F5/34 wasn't thus grabbed. Bristol needs to make a Fulmar killer, so that the Sea Gladiator is replaced by the Type 153 (or whatever) well before the Fulmar idea comes about.

I confess that I did miss a (brief) reference to the FAA in Tomo's OP.

However, his premise was that first the Bristol 153 must win the F.7/35 for a cannon armed fighter. Which is hard to see happening.

I wonder about how the supply of Hercules engines would affect development and production of the 153,

It was such an issue that the Beaufighter II was created, using Merlins instead.

Not forgetting that the Hercules was to power the Beaufighter, Wellington, Short Stirling and was to be used on the Supermarine B.13/36 until the project was cancelled after the prototype was destroyed.

I think service entry for the 153 would be similar to the Beaufighter and Stirling, or a bit after. So, mid-to-late 1940, too late for impact in the BoB. Maybe they show their mettle "leaning into France"?

Back to the FAA situation: when would we expect navalised version of the Type 153?

First flight of a (non-navalised) Type 153 would be no earlier than 1939, IMO. Then it would have to show sufficient performance to pique the interest of the FAA.

 

[Admiral Beez]

Back to the FAA situation: when would we expect navalised version of the Type 153? First flight of a (non-navalised) Type 153 would be no earlier than 1939

We must beat the Fulmar to market. First Fulmar flies in Jan 1940, with entry into service only a few months later in May 1940. This short timeframe was due to the Fulmar being based on an existing design, the Fairey P.4/34. The Air Ministry had expected the unit cost to be competitive, but the Fulmar ended up costing £8,000 when a Spitfire was only £6,000.

So to get the Naval Type into service we must enter service before Jan 1940 and cost about the same as the £6,000 Spitfire. What about converting the Type 148 into a single seater with the eight gun armament of the Type 146? Swapping in the much larger and heavier Hercules will be tricky, but I'm more suggesting using some parts from these two existing aircraft to reduce the overall development time and cost, thus beating the Fulmar. The Type 148 has the same wingspan and nearly the same length as the heavier Hawker Hurricane - not an entirely bad start for a fighter than need only outperform the Skua to get noticed.

Then it would have to show sufficient performance to pique the interest of the FAA.

The two fighters in service with the FAA in 1938 were the Sea Gladiator and Blackburn Skua. So the bar for sufficient performance is quite low. Anything close to a Hawker Hurricane will more than suffice to win the contract, provided we beat the Fulmar on date to entry and cost.

 

[Shortround6]

There are several problems with the type 153 especially for a carrier fighter.

All of the airframe problems could be fixed (maybe) but that takes more time and development.
Go back at look at post #6 for some of of the published specifications of the 153.

Like the 85 gal fuel capacity. Less endurance than the Hurricane and Spitfire. The plane is using a higher powered engine and has more drag, not a good combination for endurance.
Like the 204 Sq ft wing. Which could mean a higher stalling speed than a plane with a bigger wing.
Especially when using a thin section wing that won't hold the Hispano gun.
Then you need to adapt the plane for carrier use. Forget about catapult fittings or fitting a hook.
You need to make sure the plane can stand up to repeated catapult launches and repeated deck landings.
The Buffalo could not and it was designed to be a carrier fighter.
A Hurricane had almost 30% more wing area than the 153 and any modifications that had to be done had more wing to support them.
The Martlet had about 30% more wing area than the 153, used a lighter engine, and on the early versions, less gun weight but more ammo.

The 153 seems to be a bit optimistic for weight for a land plane, a navel version would be several hundreds pounds more.

The availability of the Hercules engine in 1939-40 is a different issue. They certainly planed to use it in number of planes. The number of airframes that got them in 1939 and early 1940 were rather limited.