Build an improved Gloster F5/34 (2 Viewers)

[ThomasP]

oops, wrong thread

 

[Shortround6]

To be fair, Napier (then English Electric) did merge with Bristol, but not until the 1960s.

To be fair, the British government at the time, forced a number of mergers on the Aerospace industry.

They didn't actually force the merger/s but it was merger or go bankrupt.

At times it was a condition of bidding on contract that any bidding companies had to merge with another company.

In the 1950s it some ways it may have made some sense as there were too many British companies to split the market between.

And you had large and small companies, however even the largest (which could have done the work without a partner) were forced into merging.

A problem for British Aerospace was that this "policy" went through several rounds. And if two companies merged and built a prototype and failed to get the production contract they could not "un-merge". The British government did, in fact, fail to issue production contracts for several programs after the forced mergers.

However, for political reasons, this policy was carried to the extreme of having one major engine maker and one major airframe maker.

And then the politicians were surprised when there was no competitive bidding on a contract, it was either take the bid cost and buy British or it was buy overseas.

Please remember that BOAC was a government owned/controlled airline so if a company didn't merge it not only lost any British military contracts but any major British civil contracts.
One or more of the Airliner programs had this mandatory merge condition.

 

[Shortround6]

The RAF was happily moving on from Mercury engined Lysander to Perseus ones with the spare Mercuries going into the Blenheim production lines, so I doubt if the idea of production Glosters having Perseus ones would put them off. Perseus were also being specified for the Blackburn Botha and initial Bristol Beaufort designs at the time.

And here is where the sleeve valve Kool-aid really kicked in.

The Perseus may very well have offered a number of advantages over the Mercury in in 1936-37-38. But the Mercury was almost in stasis as far as development went. Just enough development to remain a viable product while the Perseus was to take over.

The original Botha and Beaufort specifications might have been doable. But when the specification was changed from the 3 man crew to 4 man and a newer wider (heavier) fuselage the Perseus could not provide the needed power.
The promised/wished for extra power of the sleeve valve Perseus over the Mercury pretty much vanished. The Perseus X engine offered 880hp at 15,500 vs the Mercury's 840hp at 14,000. Better but not enough to change the performance of any of the aircraft powered by it any meaningful way. Under 8% at altitude and just under 4% at take-off when using 87 octane fuel.
Maybe Bristol had inside knowledge (?) but the Air ministry allowed them to change to the Taurus while Blackburn was stuck with Perseus .

Please note that any higher power Perseus engines that saw production were Medium Altitude (6,500ft ?) engines with cropped impellers.

Perhaps Somebody could have/would have ordered a quantity of Gloster fighters with Perseus engines but there would have been no significant increase in power.
How much of this was known in 1938-39 I don't know. But there were problems with Perseus production as production ramped up during those years. Making scores of engines per month was different than making much lower numbers. The Taurus soon displayed it's overheating problems and whatever problems the Hercules had was compounded by the same problems the Perseus had. They used pretty much the same cylinders/heads and sleeves.

Now for how long it took to change engines and how far they had to plan ahead the Wellington is instructive.
While the Wellington first flew in June of 1936 a much modified form first flew in Dec 1937.
In Jan of 1938 they were already looking at different engines but the engines were not ready for production so orders were placed for the Pegasus powered version/s. IA and so on.
The MK II with Merlin's started at this time. Delay's in Melrin X engines meant that first prototype flew March 1939. It entered service near the end of 1940.
The MK II with Hercules engines also started at this time (Jan 1938) but first flight wasn't until May of 1939. However first operational use wasn't until June of 1941.
The MK IV with P & W R-183) was proposed in late 1939. Problems with US neutrality took until Feb 1940 to sort out. First Prototype flies in Dec 1940 and first operational use was in Aug 1941.

Now for the Hercules we can note it took a very long time to go from prototype to operational use. At times the Sterling had priority, which is one reason for the Beaufighter II with Merlin's. However both Stirling production lines were bombed so planned Sterling production was much smaller than planned in late 1940 and 1941.

The Hercules was having production problems relating to the sleeve valves. It is hard to believe that the Perseus wasn't having problems at the same time as they cylinders were so close to each other.
The "promised/hoped" for increases in power for the Perseus never came.
The Hercules got better but they needed not only to solve the Sleeve valve production problem but they needed more cylinder fins and new cylinder head design to increase cooling among other changes.

 

[Admiral Beez]

The RAF was happily moving on from Mercury engined Lysander to Perseus ones with the spare Mercuries going into the Blenheim production lines, so I doubt if the idea of production Glosters having Perseus ones would put them off. Perseus were also being specified for the Blackburn Botha and initial Bristol Beaufort designs at the time.

Good points. Interestingly, Bristol chose the Mercury for their own Type 146, first flying in 1938. You'd think they'd have chosen the Perseus if they believed it had a future.

 

[yulzari]

And here is where the sleeve valve Kool-aid really kicked in.

The Perseus may very well have offered a number of advantages over the Mercury in in 1936-37-38. But the Mercury was almost in stasis as far as development went. Just enough development to remain a viable product while the Perseus was to take over.

The original Botha and Beaufort specifications might have been doable. But when the specification was changed from the 3 man crew to 4 man and a newer wider (heavier) fuselage the Perseus could not provide the needed power.
The promised/wished for extra power of the sleeve valve Perseus over the Mercury pretty much vanished. The Perseus X engine offered 880hp at 15,500 vs the Mercury's 840hp at 14,000. Better but not enough to change the performance of any of the aircraft powered by it any meaningful way. Under 8% at altitude and just under 4% at take-off when using 87 octane fuel.
Maybe Bristol had inside knowledge (?) but the Air ministry allowed them to change to the Taurus while Blackburn was stuck with Perseus .

Please note that any higher power Perseus engines that saw production were Medium Altitude (6,500ft ?) engines with cropped impellers.

Perhaps Somebody could have/would have ordered a quantity of Gloster fighters with Perseus engines but there would have been no significant increase in power.
How much of this was known in 1938-39 I don't know. But there were problems with Perseus production as production ramped up during those years. Making scores of engines per month was different than making much lower numbers. The Taurus soon displayed it's overheating problems and whatever problems the Hercules had was compounded by the same problems the Perseus had. They used pretty much the same cylinders/heads and sleeves.

Now for how long it took to change engines and how far they had to plan ahead the Wellington is instructive.
While the Wellington first flew in June of 1936 a much modified form first flew in Dec 1937.
In Jan of 1938 they were already looking at different engines but the engines were not ready for production so orders were placed for the Pegasus powered version/s. IA and so on.
The MK II with Merlin's started at this time. Delay's in Melrin X engines meant that first prototype flew March 1939. It entered service near the end of 1940.
The MK II with Hercules engines also started at this time (Jan 1938) but first flight wasn't until May of 1939. However first operational use wasn't until June of 1941.
The MK IV with P & W R-183) was proposed in late 1939. Problems with US neutrality took until Feb 1940 to sort out. First Prototype flies in Dec 1940 and first operational use was in Aug 1941.

Now for the Hercules we can note it took a very long time to go from prototype to operational use. At times the Sterling had priority, which is one reason for the Beaufighter II with Merlin's. However both Stirling production lines were bombed so planned Sterling production was much smaller than planned in late 1940 and 1941.

The Hercules was having production problems relating to the sleeve valves. It is hard to believe that the Perseus wasn't having problems at the same time as they cylinders were so close to each other.
The "promised/hoped" for increases in power for the Perseus never came.
The Hercules got better but they needed not only to solve the Sleeve valve production problem but they needed more cylinder fins and new cylinder head design to increase cooling among other changes.

I am not especially supporting the use of the Perseus but it does seem to have had little trouble in service, albeit with low to medium level roles, but did the job insofar as such an engine size could. Had the Gloster gone into production one might wonder if they would have optimised the supercharger for higher levels. My point is merely that the RAF were not opposed to the Perseus itself. More of an issue might be the size and power to do the fighter task in service. My view is that one needs to either bolt more engine on the front or bolt less aeroplane on the rear

One might, over simplistically, think of the Perseus as half of a Centaurus with smaller cylinders and, crudely extrapolating just for the fun of it, you get back to the post war Perseus with Centaurus cylinders at 1,200 bhp for civilian use so maybe stressing it a touch further to 1,350bhp in military use. That would make it handy when introduced but soon falling behind the curve by 1942.

 

[Admiral Beez]

I wonder what we would have seen had Bristol disregarded sleeve valves from the onset, and instead focused on making the Jupiter, Mercury, Neptune, Pegasus, etc. A twin row 45L Pegasus to compete with the 46L P&W R-2800 Double Wasp?

 

[Shortround6]

I am not especially supporting the use of the Perseus but it does seem to have had little trouble in service, albeit with low to medium level roles, but did the job insofar as such an engine size could. Had the Gloster gone into production one might wonder if they would have optimised the supercharger for higher levels. My point is merely that the RAF were not opposed to the Perseus itself. More of an issue might be the size and power to do the fighter task in service. My view is that one needs to either bolt more engine on the front or bolt less aeroplane on the rear

Optimized how????

At 880hp at 15,500ft the engine was already doing pretty well, if you want more altitude you need to put more power into the supercharger. Which means less power to the prop.
WIth a single speed supercharger you are kind of stuck, increasing the power or altitude in the upper teens means less power at all the lower altitudes.

The lower altitude Perseus used crop impellers and/or different supercharger drive ratio. They got them up to about 950hp at 5-6000ft. But power at 15,000ft sucked.

One might, over simplistically, think of the Perseus as half of a Centaurus with smaller cylinders and, crudely extrapolating just for the fun of it, you get back to the post war Perseus with Centaurus cylinders at 1,200 bhp for civilian use so maybe stressing it a touch further to 1,350bhp in military use. That would make it handy when introduced but soon falling behind the curve by 1942.

Getting tired of answering this one. There is not a whole of evidence that the Post war Perseus ever existed. No record it every flew in any aircraft even for a test. No known photograph of it.
Radial engines don't like "maybe stressing it a touch". they tend to come apart.
And we are back to the sleeve valve kool-aid.
The post war Perseus 100 was supposed to be 1635 cubic inches.
It took Wright until some time in late 1943 or into 1944 to get 1350hp for take-off out of the R-1820 engines used in the FM-2 Wildcats. They needed a different crankshaft than the 1300hp versions which were and entirely engine than the 1200hp Cyclones, they used different crankcases and crankshafts, thse "H" series engines used more hold down bolts per cylinder. They used a new form of cylinder fins with sheet metal fins rolled into grooves in the cylinder barrel, they used a new cylinder head and most of the other parts (valves etc) were new.
And the Wright engine was about 11% bigger than the Perseus 100. But heck, the Perseus 100 used sleeve valves, it must have made more power
The specifications for Perseus 100 claim 1220hp at 4,000ft, take off is slightly lower and the rating was at 9.5lbs of boost.
Now one problem in using the Centaurus size cylinder is that it is the same diameter as the Perseus/Hercules cylinder. They added 13mm of stroke.
What this means is the when the Perseus is running at 2750rpm the pistons are moving at 2979 fpm. When a Hercules is running at 2800rpm the pistons are moving at 3023 fpm but when a Centaurus is running at 2700rpm the pistons are moving at 3150fpm. Over revving it doesn't look good.
And they had a problem with sleeve valves. When you raise the boost pressure the pressure in the cylinders also goes up, they tended to break, bend, crack the edges of the sleeve valve ports which then lead to the sleeve jamming, freezing in the cylinder. They did a lot of work making stronger sleeves as the war went on (and post war) to handle the higher boost pressures. They also had cooling problems, To get the heat out of the cylinder the heat has to travel through the sleeve and the layer of oil between the sleeve and the cylinder barrel. In a poppet valve engine the heat goes through the oil on wall and then right into to the cylinder barrel.
If set up (designed) right the engine can take the designed load, but there was not the "headroom" that liquid cooled engines had for over boosting.

 

[Elvis]

...skip...

 

[Shortround6]

Bristol also had a bit of work to do on poppet valves.

One grease fitting on each valve and another one in-between the rocker shafts?
18 cylinder engine= 72-90 grease fittings every how many hours?

 

[yulzari]

Optimized how????

At 880hp at 15,500ft the engine was already doing pretty well, if you want more altitude you need to put more power into the supercharger. Which means less power to the prop.
WIth a single speed supercharger you are kind of stuck, increasing the power or altitude in the upper teens means less power at all the lower altitudes.

The lower altitude Perseus used crop impellers and/or different supercharger drive ratio. They got them up to about 950hp at 5-6000ft. But power at 15,000ft sucked.

Getting tired of answering this one. There is not a whole of evidence that the Post war Perseus ever existed. No record it every flew in any aircraft even for a test. No known photograph of it.
Radial engines don't like "maybe stressing it a touch". they tend to come apart.
And we are back to the sleeve valve kool-aid.
The post war Perseus 100 was supposed to be 1635 cubic inches.
It took Wright until some time in late 1943 or into 1944 to get 1350hp for take-off out of the R-1820 engines used in the FM-2 Wildcats. They needed a different crankshaft than the 1300hp versions which were and entirely engine than the 1200hp Cyclones, they used different crankcases and crankshafts, thse "H" series engines used more hold down bolts per cylinder. They used a new form of cylinder fins with sheet metal fins rolled into grooves in the cylinder barrel, they used a new cylinder head and most of the other parts (valves etc) were new.
And the Wright engine was about 11% bigger than the Perseus 100. But heck, the Perseus 100 used sleeve valves, it must have made more power
The specifications for Perseus 100 claim 1220hp at 4,000ft, take off is slightly lower and the rating was at 9.5lbs of boost.
Now one problem in using the Centaurus size cylinder is that it is the same diameter as the Perseus/Hercules cylinder. They added 13mm of stroke.
What this means is the when the Perseus is running at 2750rpm the pistons are moving at 2979 fpm. When a Hercules is running at 2800rpm the pistons are moving at 3023 fpm but when a Centaurus is running at 2700rpm the pistons are moving at 3150fpm. Over revving it doesn't look good.
And they had a problem with sleeve valves. When you raise the boost pressure the pressure in the cylinders also goes up, they tended to break, bend, crack the edges of the sleeve valve ports which then lead to the sleeve jamming, freezing in the cylinder. They did a lot of work making stronger sleeves as the war went on (and post war) to handle the higher boost pressures. They also had cooling problems, To get the heat out of the cylinder the heat has to travel through the sleeve and the layer of oil between the sleeve and the cylinder barrel. In a poppet valve engine the heat goes through the oil on wall and then right into to the cylinder barrel.
If set up (designed) right the engine can take the designed load, but there was not the "headroom" that liquid cooled engines had for over boosting.

You know I thought that I had carefully worded my thoughts as idle musing; but it would seem not.

 

[Admiral Beez]

So starting with the F5/34 what do we need to get it up to or near 109E standard.

1935, Folland consults with Bristol on the engine to use with his F5/34 design then on the drawing board, where he learns of the two row, 14 cylinder Taurus and Hercules then in development. Of note, both the F5/34 and Taurus are first flown/run in Nov/Dec 1936, while the Hercules first ran ten month earlier in Jan 1936. Design and build the F5/34 to use the Taurus initially with plans to switch to the Hercules and much of the rest of the F5/34 can be forgiven.

 

[Shortround6]

Of note, both the F5/34 and Taurus are first flown/run in Nov/Dec 1936, while the Hercules first ran ten month earlier in Jan 1936.

There is a difference between first flight of a prototype aircraft and the first run (on a test stand) of a prototype engine. It was often 1 to 2 years after an engine was first run that that put one in an aircraft to actually fly.
and look at your own time line.
"Of note, both the F5/34 and Taurus are first flown/run in Nov/Dec 1936, while the Hercules first ran ten month earlier in Jan 1936."

The Taurus was not a stepping stone to the Hercules. It was a step backwards.

And then you have the problem, mentioned before, of taking an planned 1100lb engine (Perseus) out of a empty weight 4190lb airplane and sticking a 1850lb engine (Hercules I) in it's place. By the time you are done you might save the tail wheel. You might save the external shape of the F5/34 but you have to restress (beef up) the entire airframe.
This is a bigger change than swapping a Merlin for a Griffon.

 

[Admiral Beez]

And then you have the problem, mentioned before, of taking an planned 1100lb engine (Perseus) out of a empty weight 4190lb airplane and sticking a 1850lb engine (Hercules I) in it's place. By the time you are done you might save the tail wheel. You might save the external shape of the F5/34 but you have to restress (beef up) the entire airframe.

By my last post above I've mostly given up on rescuing much of the F5/34. Instead Folland stops his design at the drawing-board stage and starts afresh with Bristol's new twin row 14 cylinder engines in mind, along with a folding wing, carrier variant from the onset. The prototype Gloster, likely a scaled-up version of Folland's original concept, will need to fly on a single row radial and ballast until either the Taurus or Hercules is ready. This puts entry into service of any 14-cyl version by 1940 at the earliest, just in time to cancel out the Fulmar.

Coincidently, the now independent Folland's first aircraft accepted by the Air Ministry was the Hercules and Centaurus powered Folland Fo.108 test bed.

 

[Shortround6]

This puts entry into service of any 14-cyl version by 1940 at the earliest, just in time to cancel out the Fulmar.

A bit optimistic.
A number of British proposals in 1938-39 had Hercules engines as primary or alternative engines.
However the state of Hercules development and production was such that in early 1940 they were looking at putting the Merlin XX into Beaufighters and Wellingtons were being set up to use P & W 1830s (a bit small but better than the Pegasus) and Merin X engines in 1939, despite flying a Wellington with a Hercules in May of 1939.
As an indication of how off track things were getting, the Beaufighter was proposed in 1938 to use a version of the Hercules that didn't exist yet, this was done around the world, and was common practice. Just look at any number of German projects where the engines showed up late or not at all. The proposed Hercules that the Beaufighter was planned for showed up in 1942 as the Hercules VI.
That is just the development and manufacturing end. From the production planning stage of things the Short Stirling was supposed to have the no 1 priority which was part of the alternative engine work. Both Shorts factories were bombed severely reducing the need for Hercules engines for that purpose. Fortunately (which was not planned on) the early Hercules production engines had a dismal record of reliability, some having to be changed in as little as 20 hours so the lower demand from Stirling production helped gloss things over. The total failure of the Lerwick program helped although production was never going to large (compared to land based aircraft)

More importantly, would this new (I will call it the Flycatcher II as it has nothing to do with F.4/34 at this point) do what you want it to do?
Yes it is smaller than the Fulmar and it has more power. It also has more drag from the engine, a lot more. And the engine is heavier than engine in the Fulmar even including the radiator.
As a "bespoke" carrier fighter instead of a land based substitute you need more range/endurance than a land based plane, how much less than the Fulmar will they accept?
Will the FAA accept the RAF ammunition load or will they insist on an ammo load closer to the Fulmar?

Add forget it being a British "Zero", the early Hercules engine was 130lbs (or more) heavier than the Mitsubishi Kasei engine used in the Raiden (Jack) and just 1in smaller in diameter.

And historically, the only reason the Taurus engine stayed in service with the Beaufort in British production was that the ship carrying 200 P&W R-1830s was sunk by a U-boat and the British could not take the risk of shipping the engines. Having scores of aircraft sitting around the factory waiting for engines was worse than flying them with poor engines.
A Taurus powered Flycatcher II would have shown a bit of an improvement over the Fulmar but not a lot.

 

[Admiral Beez]

Someone's attempt.

An Auk-ward Gloster - The Unofficial Airfix Modellers' Forum

uamf.org.uk

 

[SaparotRob]

That's a pretty cool model.

 

[Admiral Beez]

An extract from my post to the Fantasy thread.

I'd like to have seen the Gloster F5/34 swap out its Bristol Mercury (Length: 47 in, Diameter: 51.5 in, Dry weight: 966 lb), skip entirely its intended Bristol Perseus (Length: 49 in, Diameter: 55.3 in, Dry weight: 1,025 lb) and instead use a Pratt & Whitney R-1830 Twin Wasp (Length: 59.06 in, Diameter: 48.03 in, Dry weight: 1,250 lb). The 10 in. longer and significantly heavier engine will necessitate changes to the CoG. While we're at it, we'll replace the undercarriage and make a smooth lower wing surface.

Can we make this work?

 

[Shortround6]

I'd like to have seen the Gloster F5/34 swap out its Bristol Mercury (Length: 47 in, Diameter: 51.5 in, Dry weight: 966 lb), skip entirely its intended Bristol Perseus (Length: 49 in, Diameter: 55.3 in, Dry weight: 1,025 lb) and instead use a Pratt & Whitney R-1830 Twin Wasp (Length: 59.06 in, Diameter: 48.03 in, Dry weight: 1,250 lb). The 10 in. longer and significantly heavier engine will necessitate changes to the CoG. While we're at it, we'll replace the undercarriage and make a smooth lower wing surface.

Can we make this work?

Sure, if you want to use the R-1830 that made about 950hp for take-off and max continuous of 830hp at a whopping 3600ft.

https://www.enginehistory.org/Piston/P&W/R-1830/R-1830Index.pdf

If you are looking for R-1830 engines that made 1100-1200hp for take off you need one of the ones that went over 1400lbs and you probably need a heavier propeller.
Lets remember that the Curtiss 75 started at about 4800lbs and wound up at around 5600lbs with the early R-1830s used the P-36. And they had problems with the wings and landing gear that needed beefing up.

Maybe you can get it to work, but it needs a lot of changes. Don't forget to increase the size of the fuel tanks to feed the bigger engine.

 

[yulzari]

An extract from my post to the Fantasy thread.

I'd like to have seen the Gloster F5/34 swap out its Bristol Mercury (Length: 47 in, Diameter: 51.5 in, Dry weight: 966 lb), skip entirely its intended Bristol Perseus (Length: 49 in, Diameter: 55.3 in, Dry weight: 1,025 lb) and instead use a Pratt & Whitney R-1830 Twin Wasp (Length: 59.06 in, Diameter: 48.03 in, Dry weight: 1,250 lb). The 10 in. longer and significantly heavier engine will necessitate changes to the CoG. While we're at it, we'll replace the undercarriage and make a smooth lower wing surface.

Can we make this work?

Their Airships are not going to take on board a foreign made engine never mind that it will mostly be a different aeroplane by the time the changes are made. Less a NIH issue but rather a strategic one of relying upon a foreign government allowing supplies to be made and the risks of sending vital engines by sea where they can be lost to raiders or submarines. better at this time to put less aeroplane behind the Mercury/Perseus.

 

[Admiral Beez]

Their Airships are not...
better at this time to...

It's easy, with our contrarian tendencies to focus on exclaiming why something would not, could not or should not have occurred. The trick is considering how to reasonably overcome these challenges. Focus on the how, not the why not. The Australians put "foreign made engines" into their Bristol Beauforts. Perhaps, having lost interest upon their acquisition of Gloster in 1935, Hawker Siddeley Group trades the F5/34 project to Commonwealth Aircraft Corporation (CAC) in Australia, where it becomes a RAAF fighter in 1941.

I'm more interested in the technical rather than bureaucratic or policy challenge. How do we get an engine of similar diameter, but of greater length and weight into the Gloster's air frame? It's akin to going from Merlin to Griffon on a Spitfire, or BMW to Jumo on the Fw 190. We've got a lot more weight sticking out in front of the main spar than the aircraft designer's intended. The F5's designer, Henry Folland (of Gnat jet fame) did not seemingly have a lot of experience with all-metal, monoplane designs, having previously led the Gloster Gladiator program - so we'll need a lending hand if Folland is staying with the design (he resigned from Hawker in 1937).