Which aircraft would you cancel?

[stona]

I mentioned above that the Air Ministry, despite objectives to the contrary, avoided standardisation. The dangers inherent in standardisation are illustrated by the series of costly failures, including the Botha, which left the Fleet Air Arm and Coastal Command desperately short of modern aircraft in 1939.
Cheers
Steve

 

[Shortround6]

Well, when you are ordering aircraft "off the drawing board" it does help to order more than one type so if it is a turkey you have a back-up already in hand.
Unfortunately for the British the 'back-up' for the Botha was the Beaufort which used an engine that while not quite "off the drawing board" was close to it.
Using hindsight it became almost a rule in 1950s and 60s that powering a new airframe with a new engine was a recipe for disaster much more often than not.

I had not heard that the Botha was "unreliable". Under-powered, unstable, and with a poor view for the crew yes.

 

[stona]

I thought this might provide food for thought.

It's a list of aircraft factories introducing new types in 1941/2. Factory, previous type, new type.

Austin Battle Stirling
Short Sunderland Stirling
Short Harland Hereford Stirling
A.V.Roe Blenheim Lancaster
Armstrong Whitworth Whitley Lancaster
Handley Page Hampden Halifax
English Electric Hampden Halifax
Rootes Blenheim Halifax
De Havilland Various Mosquito
Bristol Blenheim Beaufighter
Gloster Hurricane Typhoon
Westland Lysander Spitfire

[PRO AVIA 10/311]

Cheers

Steve

 

[GrauGeist]

Well, when you are ordering aircraft "off the drawing board" it does help to order more than one type so if it is a turkey you have a back-up already in hand.

The case of the B-29 and it's backup, the B-32, comes to mind.

 

[kool kitty89]

The case of the B-29 and it's backup, the B-32, comes to mind.

That case also has the common problem of 'new aircraft with new engine' (or at least unproven engine not yet reliable in mass production).

A safer backup plan would've been a slightly smaller aircraft using the more proven R-2800. (backups targeting yet OTHER unproven engines -like the V-3420, let alone even more problematic super-engines would be equally bad considerations)

In Brittain's case, importing engines as a failsafe would have been an option, and pre-war they had both France and the US to consider (the 14N, R-1820, and R-1830 being the most useful examples, with the 12Y interesting as a Peregrine alternative). The two problems there (monetary cost aside) are integrity of shipping lanes and potential fall of said exporters to the enemy (and political/economic issues bottlenecking supply at the source for other reasons).

Honestly, given how dependent the UK already was on shipping for all sorts of resources (including fuel) and how isolation would pretty much mean inability to fight effectively in any case, that trade-off probably wasn't a serious dealbreaker.

Licensed production could be a consideration too, but given the cost and (especially) time overhead, just placing sufficiently large/consistent enough orders for import (to secure steady production/supply from the source) would likely have made more sense. (this all long before wartime ... let alone lend-lease, of course)

The R-1830 Twin Wasp was only a good replacement for the Pegasus, too wide for most other direct replacements (though slow, high drag aircraft probably wouldn't loose much switching from the Taurus), so the R-1830 was really the best option all around. (imported or licensed or both ... of course there was licensed R-1830 production in the Commonwealth, but that was probably more significant than native British licensed production, atlantic trade of American engines being a lot more straightforward than shipping all the way to Austrialia or New Zealand -Canada would of course have good land access to American engines too) Given its proven design and low frontal area (for a radial engine its size) it seems like the obvious pre-war engine option to supplement British technology.

The R-2800 would be the obvious stop-gap for the Centaurus production delays as well as potentially displacing the Saber in general use as a 2000 HP class engine. (import over licensing still likely made more sense, if not more so due to the newer design and more dire war-time situation in the UK. (the R-2600 may have also been a consideration for supplementing Hercules supply, but given the relatively trouble-free history of that engine -and the R-2600's own problems at times- it's not a significant example where such considerations would have developed into genuine necessity) The R-2800 also developed substantially more during war-time, compared to the R-1830, so any licensed production would have been constantly playing catch up (or stuck making older, less powerful models) in a far less efficient or useful capacity than R-1830 production might. (even sticking with one of the 1200 HP single-stage variants -like what the Aussies ended up building- would have been useful for most/all needs of such an engine, particularly with maritime use -plus even the 2-stage variants didn't have the level of mechanical differences as the R-2800 A vs B vs C series which were largely entirely new engines given the level of changes made)


The R-1830, aside from the obvious fit to the Beaufort (and potentially any other Taurus powered production aircraft) would have made perfect sense on Gloster's F.5/34 monoplane and F.9/37 twin. (both likely taking much less modification than a Merlin refit would -the only other really viable 1000+ HP class engine of the period, and of course would compete for production with other Merlin powered types)

 

[Shortround6]

Man, you sure do have a love affair going on with Gloster's F.5/34

To me it seems too good to be true.

20-25mph faster than either the P-35 or P-36 at around 15-16,000ft using about the same power?
Or about the same speed as a Macchi 200 which had about 50 sq ft less wing area? and had fully enclosed landing gear?
same speed (or within production tolerance of a few %) as a Hawker Hurricane? That could out climb it to 20,000ft by several minutes?

Or 29mph faster than the Bristol F.5/34 which used the same engine?

granted the airflow around the Canopy on the Bristol may be a little suspect (or more than a little?) but the landing gear on the Gloster is about as bad as it gets for late 1930s fighter. Seversky giving up on that style by 1939.

You have two choices, license the the Boeing patent for landing gear and have the wheels rotate 90 degrees to lay flat in the wing (P-36/P-40/Re.2000 style) or redo the wing and have the lading gear retract inward (P-43 style).

 

[GrauGeist]

That case also has the common problem of 'new aircraft with new engine' (or at least unproven engine not yet reliable in mass production).

A safer backup plan would've been a slightly smaller aircraft using the more proven R-2800. (backups targeting yet OTHER unproven engines -like the V-3420, let alone even more problematic super-engines would be equally bad considerations)...

If you're not going to build the aircraft for fear of the engines, then cancel it and continue on with the B-17 and B-24 (smaller aircraft).

The USAAC (USAAF) requested a step foreward in range and load and the B-29 was their choice. It happens that the XB-19 most likely would have been chosen over the B-29 had it not been for project delays.

Interestingly enough, the XB-19 used the V-3420, which is the same engine the XB-39 (B-29 backup) used.

 

[kool kitty89]

Self-sealing tanks means both a weight penalty and a tank volume penalty. Both have a negative impact on range.

This is significantly more true for full self sealing fuel cells rather than the simpler (albeit less effective) method of coating conventional metal tanks in self-sealing material (like linatex or similar). It's possible that some British Aircraft made the compromise to retain this older implementation for weight and fuel capacity reasons.

The P-40C gained weight and lost significant internal fuel capacity switching from the P-40B's self-sealing coated metal tank (the P-40D and E expanded this at the expense of yet greater weight gain). The F2A also suffered significantly when transitioning from its integral wing tanks to the self sealing fuselage tanks introduced in the F2A-3. (whereas the British-compliant B-339 simply took the F2A-2's unprotected tanks and added external self sealing material, adding relatively little weight and at least acceptable sealing and fire resistant qualities -given the serious problems the F2A-3 faced, it may have been a smarter compromise)

American aircraft were generally better protected and overengineered compared to their British and German counterparts, and that goes for even pre-war aircraft as far as excessively stringent structural integrity requirements. (hence their typically greater weight -even the F2A was relatively rugged compared to land-based aircraft, Brewster's own quality control problems notwithstanding -particularly after war broke out and orders exceeded their capacity ... or if not potential capacity, at least real-world capacity limited by severe management issues, shame there wasn't a Naval Aircraft Factory variant like the SBN)


In fact, that leads int one of the best arguments I have for an aircraft that SHOULD have been canceled: the F2A-2 and F2A-3. As soon as Brewester's production capacity began to show trouble (yet again) during the initial F2A-1 (and B.239) run, the USN should have licensed the design and shifted 100% of Naval production to the Naval Aircraft Factory (so the F2A-2 and F2A-3 would be FN-1 and FN-2 or some such) and possibly also considered outsourcing to Grumman for production rather than building the Wildcat at all. (a 2-stage R-1830 powered F2A with reliable production facilities likely would have been more capable than the F4F-3)

Leave Brewster to handle export production exclusively (B.239, 339, 439, etc) and also cancel the F3A Corsair. (if they were too unreliable to produce their own aircraft, there's no way they could be trusted with another firm's, particularly an advanced new generation fighter) Navalized export models might have been a good idea and potentially more useful with the FAA than the land-based Buffalo had been with the Commonwealth. (performance compares well with the Martlet, with some advantages in maneuverability, cockpit visibility, smaller size on deck -without folding wings- higher ammunition capacity, more reliable machine gun mounts, and powered automatic landing gear without the failure to lock the Wildcat/Martlet suffered from -though other failure issues when overladen on hard deck landings prior to the tests revealing reduced tire pressures alleviated this problem) Basically the British could have really used the Buffalo Mk.I with the original small tailwheel and arrester hook of the F2A-2 retained.

Leading into my earlier R-1830 comments (and longer previous post on engine imports). Aside from the high altitude performance of the 2-stage models, even the basic single stage units (used in some Martlets) would have benefitted the F2A more than the F4F due to its significantly smaller size and somewhat lower weight. (the bulky F4F lost rather little when switching to the much wider R-1820, but the F2A had the engine cowling nearly as wide as the fuselage itself, a fair more cylindrical arrangement to the bulkier curve the Wildcat features amidships, so the R-1830 should have had a significant decrease in nose area and drag even with the spinner omitted) All the better if the FAA/RAF focused on the R-1830 as their standard import engine of that size/type (let alone potentially displacing the Taurus entirely).


The F.5/34 was an interesting option for FAA fighter use as well (better flying qualities for deck handling than the spitfire and much better aerodynamics -and shorter wingspan- than the hurricane, let alone other technical -and fire danger- issues the hurricane posed to carrier and pilot alike), but even had it been adopted as such I think the Buffalo could have made a fair complement to it. (both had very nice all-around vision through their canopies as well, particularly important for Naval aircraft)

The F.5/34 is also notable even in its Mercury powered form for at least being a better pre-war option than the Sea Gladiator while using the same engines and production facilities. (albeit obviously with some overhead/delay in tooling up for the new design) And while the FAA had other requirements that demanded the 2-man arrangement fo the Fulmar and Firefly, the fact was they still had a use for single seat fighters and were indeed receiving newly built Gladiators for that purpose pre-war.

Yep, agree that the Air Staff generally seem to have under estimated the abilities of their air crew.

The drive towards two seat fighters was due to a combination of two interlinked factors. The quest for fire power and the need to fly in formation to achieve it.
A separate gunner (or gunners, several three seat aircraft were proposed in the 1930s) was considered essential as the pilot would need to concentrate on keeping the aircraft in place in the formation.
The pilot was not expected to maintain a formation and aim a gun or guns.

I was of similar opinion until the radio technology situation of 1939-1941 was explained properly. A dedicated radio operator (and optional observer) was genuinely useful for the pre/early war period to allow more complex multi-frequency radio installations and consequently more effective long-range operation with proper communication. (even more important for long range duties with small fighter groups, let alone recon or patrol duty)

This was the best justification for the 2-seat Fw 187 arrangement without defensive weapons mounted. (though it obviously still needed more powerful engines to reach its full potential, even the Jumo 210G version was competitive with the 109E and Spitfire I and II at low/medium altitudes, with similar or better speed and superior rate of climb, but lower critical altitude -Czech made pre-war Hispano 12Y's probably would have been enough to make up the difference and make for a faster, better climbing aircraft at all altitudes)

Additionally, for particularly long endurance maritime patrols, a second crewman would be useful for avoiding potentially fatal disorientation/'mesmerizing' situations like some P-38 pilots suffered in the Aleutians. (a maritime patrol/recon variant of Gloster's F.9/37 derived Twin engine fighter project(s) would have similar considerations, or any early-war variant)

Had the Air Ministry actually gone ahead with cancelling the Typhoon, 2 TAF would not have been nearly as effective as it was between late 1943 and VE-Day; sure, the Spitfire XII was arguably a better fighter, but there was no way that it was a better fighter-bomber. No Spitfire could carry 1,000 lb bombs or 8 to 16 rockets, nor could it carry the same armour protection, or dive as fast. Overall, the Typhoon turned out to be a very efficient fighter-bomber and there was nothing else in the British armoury that could have taken its place. I would, however, argue that one mistake the British did make was to lumber the likes of the Typhoon and Mosquito with heavy, bulky rocket rails; by 1944 zero-length launchers had been proven in operational service and should have been made a priority.

That's only if there's no proper replacement for the Typhoon ... the Spitfire couldn't do its job, but a twin-engine fighter could have. Either continued development of the Whirlwind (or, more likely somewhat heavy redesign to properly accommodate the merlin AND address the weaknesses of the initial Whirlwinds -malfunctioning slats, lack of fuel crossfeed, etc). The Gloster design may have been easier to adapt with its larger wing and easier potential internal fuel capacity (with functional slats, the Whirlwind likely could have done some good heavy lifting, but fuel capacity would have been a challenge unless perhaps they sacrificed drag, using chin mounted radiators and filled the wings with more fuel tanks in place of the embedded radiators)

Having Napier and Son focus on licensed Merlin or especially Griffon production likely would have made more sense and pursuing the Saber project. (or for that matter, licensed Peregrine production, and avoid the major overhead in Whirlwind redesign, just allow the Peregrine to properly mature as an engine adopting similar improvements to the Merlin while not disrupting Rolls Royce manufacturing efficiency by producing multiple engine types -that's the source of the '1 peregrine costs 2 merlins' context, not a matter of individual cost but loss of efficiency when not producing Merlins and ONLY Merlins) The Peregrine's problems are often exaggerated and likely could have matured in parallel with the Merlin with similar power and altitude performance relative to its smaller displacement. (ie likely upwards of 1100 HP next to the Merlin 45, and short of a 2-stage version, adopting the larger Merlin 45/XX series supercharge and 2-speed drive could have made for pretty decent high altitude performance on the smaller engine)


Or do both the Whirlwind and Gloster twin, with the latter focused more on maritime operations and ground attack with the advantage of more durable R-1830s. (ie a better performing, smaller, lower cost Beaufighter alternative)


Also remember Hawker owned Gloster and ... could/should have been building the likes of F.5/34 and F.9/37 variants in place of the obsolete Hurricane and troubled Typhoon. (and those Merlin XXs going to Hurricane IIs could have gone to bombers ... or the Spitfire III could have been brought to production -and also better matched the early Fw 190 at low altitudes thanks to 2-sped drive, especially with LF style clipped wings) Or, of course, the F.5/34 could have been adapted to Merlin XX power and ended up closer to a British P-40 but probably a fair bit lighter weight and consequently less underpowered. (similar excellent aileron control and roll rate though)

Canada could have been building F.5/37 variants rather than Hurricanes as well. (be it packard Merlin powered like their historical Hurricanes, or R-1830 powered) And would have been a good fit for CAC licensed production alongside their Wirraway. (or DAP alongside the Beaufort)


Hmm ... I suppose there's a rather heavy theme with my arguments: if you cancel something, you need something better to replace it. (either a matter of producing MORE of something else, or something better that was overlooked/abandoned entirely) There's relatively few cases where canceling something outright and replacing it with nothing (and pocketing the wasted resources) was all that useful.

If you want to ditch the P40 in the desert, why not replace it with a P39 that has a 20mm cannon in place of the 37mm, remove the wing guns and some of the armor and turn up the boost on the Allison so it can fight below 12,000 feet just like the Russians did. The Russians thought it was superior to the P40 and the Hurricane. In tests it was considered the equal of the Spitfire below 15,000 feet.

The P-40 was easier to fly and maintain, had a better bombload and better maximum range.

The P-39 (more so in some models) was a maintenance nightmare by comparison, had a more cramped cockpit (thanks in part due to the NACA redesign request dropping the originally larger canopy), and had dangerously sensitive CoG issues leading to irrecoverable flat spins when the aircraft was nose-light (ie improperly loaded or after expending some/all ammunition). Replacing the 37 mm cannon with a Hispano would make that issue a bit worse as well. (there may have been other solutions to those problems, but they required further modifications ... the NACA's rear-fuselage/tail lengthening of the XP-39 probably is partially at fault for shifting the CoG rearward as well) The Range issue might have been alleviated by fuel cells in place of the wing guns (and with the 20 mm in the nose, still would have been a competent fighter armament) but wouldn't address the maintenance or spin issues. (similar to the spin issues, the plane also liked to drop a wing at low speeds, complicating landing similar to the F4U and making the rather nice tricycle gear less of a boon to handling on takeoff/landing)

 

[kool kitty89]

If you're not going to build the aircraft for fear of the engines, then cancel it and continue on with the B-17 and B-24 (smaller aircraft).

A bomber optimized around the limitations of four R-2800s could have at least approached those new requirements while far exceeding the existing heavy bombers in production. (technically the R-2800C family had the take-off/emergency power to supplant the R-3350 directly ont he B-29, but would have left it too slow at economical cruise settings or too short ranged if using max continuous power -ie not lean mixture)

The only other 'foolproof' engine option would have been a full six R-2800s, definitely within power abilities even using the older B series, some obvious gains to drag over 4 engines, but probably not enough to break it, and definitely enough power at take-off and cruise to meet the full range of abilities the B-29 was expected to accomplish.

The issue was what could you get into production faster and was reliable. Centrifugal engines leveraged off existing supercharger knowledge and production abilities. For example, the RR Nene was a 5,000lb thrust engine that was more reliable and far in advance of any axial flow ones of the time (late '44).

Unfortunately, the compressor type used had little to nothing to do with the problems the Germans faced (centrifugal engines have other advantages, like shorter length, better spool up time, and lower weight, though, and Heinkel/Ohain had a rather novel method of sheet metal bladed compressors that avoided the high cost of machined centrifugal impellers like Rolls Royce/Whittle/GE/etc used, let alone their particularly expensive double-sided impeller arrangement).

The problems (like with British engines) were mostly limited to combustion stability and overheating issues. Whittle countered this with gradually improved combustion chamber design and brute-force super-alloys (the initial turbine alloys continued to fail until the super high nickle+chromium content Nimonic alloys were employed). BMW took a while to sort out their annular combustion chamber design, but ended up with an exceptionally long-lasting one made out of only mild steel while Jumo made more modest achievements in this with their 004D. (still much improved over the B)

The 004 was actually an extremely conservative engine design to the point of fault (hence its high weight and poor fuel consumption) aimed at being ready for mass production as soon as possible. This could have paid off if not for the critical issues of vibration the design suffered multiple times (both in the compressor and turbine sections). Part of this was putting so much work into the proof of concept (but impossible to mass produce) 004A. Had they at least used COMMON high temperature alloys (like tons of stainless steel, but not super proprietary stuff) they likely would have caught some of those turbine vibration problems sooner and been able to address them in a reasonable scale of time, making the conservative engineering actually pay off.

By comparison, Heinkel had 1 rather conservative engine (the HeS 8) that also was troubled by combustion stability and hot spot issues as well as relatively poor compressor efficiency (troubles working with the novel axial diffusor arrangement and relatively poor airflow routing through the annular combustion chamber) and one very advanced and elegant engine in the HeS 30 which was mostly slowed by the delay in moving Junkers personnel over from their previous location and them problems with Adolf Muler's arrogance and abrasive personality but it progressed well enough to catch up with competing developments and quite possibly could have reached production before the 004B had it not been canceled in 1942. (though honestly, the project should have stayed at Junkers and the combined Junkers Aircraft team -Wagner/Muler/others who left for Heinkel and Jumo engine team should have developed the two engines in parallel, sharing information and making the best of both worlds to hedge their bets -had both actually reached production at similar times, the Wagner/Muler engine would have produced the same thrust at roughly half the weight and half the frontal area while consuming less fuel and spooling up much faster but taken a bit more machine work to manufacture -the compressor blades had to be machined rather than stamped like the 004's could be, while the Wagner/HeS 30/006/etc Engine was probably still far cheaper than any british engine but a bit more labor intensive -and requiring high speed steel/carbide cutting tools increasingly in short supply- than the 004 or 003).

With the combustion problems involved (and large mass of stainless steel needed for the radial turbine) Ohain probably should have adopted flame cans and an axial turbine to further develop his centrifugal compressor schemes. (particularly borrowing from progress on the HeS 30)

That said, the HeS 8 actually has an extremely impressive small frontal area and should have scaled up well to an engine more in the Goblin class (and much easier to engineer and manufacture than the HeS 011) so that axial diffusor did have at least some merit. (the post-war Fairchild J44 is an interesting counterpart to compare in that respect, among a few other super-slim single-stage Centrifugal engines) OTOH for a stop-gap, he really should have continued working with the very functional and less troublesome HeS3b and HeS6 and either refining them for reliable mass production (and Heinkel designing aircraft expressly around those engines limitations) and/or further scaling those engines up. (their frontal area was already much lower than Whittle's counterparts, and weight of the HeS-3b wasn't far off from the W.1's weight or thrust values either -the critical shift likely would have been air cooled turbine blades allowing higher power settings akin to Whittle's switch to nimonic blades). Abandoning all more advanced features (axial diffusor, 2-stage centrifugal or axial compressors, and possibly even sticking with the radial turbine -given it worked ... reliably enough for flight testing years ahead of Whittle or any other German engine) would have been the best option for Ohain/Hirth to focus on getting engines into mass production as soon as possible. (the HeS 6 was the best bet IMO, and directly scaled up variants thereof ... given the success it had in 1939 and the massive delays in everything else, it could have meant the He 280 -with corespondignly different engine mount configuration- flying nearly a year earlier and possibly reaching preproduction and operational testing status in 1941) It almost seems like sheer good luck that the primitive combustion chamber arrangement of the HeS 3 and 6 actually worked as well as it did, but equally understandable why Ohain had such trouble with the HeS 8. (the HeS 3 and 6 arranged long jets -almost like blow torches or blow lamps- in a ring inside a big open chamber OUTSIDE the compressor and turbine disks, the diffusor was folded forward and packed in front of the compressor with outlets to the flame jets more or less in line with the compressor hub itself, thus giving the distance between the compressor hub and turbine inlet for combustion to progress with little/no drag or containment and then smoothly flow the exhaust gases inwards towards the radial turbine though a ring of radial stator blades; the HeS 8 used a contorted cramped arrangement that didn't allow such linear airflow around the engine but instead forced it into a much narrower area between the two compressor disks, also increasing engine weight due to the longer shaft between rotors)

See:
View: https://www.youtube.com/watch?v=z_RSHrGKyDg


The initial versions also relied on vaporized fuel jets, require starting/warmup on hydrogen before shifting to gasoline/kerosene (very much in common with warmpup periods for blow lamps), though I'd expect use of ether and/or methanol would have worked as well due to the ease of vaporization and lack of smoke. (soot would clock the injectors if kerosene was injected prematurely) I'm slightly surprised Heinkel didn't just run his initial flight tests with methanol or ether, or focused so much on hydrogen for proof of concept but transitioned straight to smokey petrol/kerosene type fuels. (admittedly, pulse jets might have worked better with methanol and/or ether as well -diethyl ether also has a much closer energy density to gasoline or kerosene, vs methanol which is only about half or slightly less on a weight for weight basis -a big deal when in the air and every ounce counts) Ether would have made a good alternative fuel to promote to the RLM as well ... though not as appealing as diesel/kerosene (already in wide use) it nevertheless had other advantages in cost/production. (if nothing else it would have been a reasonable starter-fluid for such jets with vaporizing burners and possibly less corrosive than methanol, but also more of a health and fire risk to the ground crew -nowhere near that of rocket fuel though)

Fuel atomization was the ideal solution, but problematic to achieve. (all engines suffered from this, and Whittle didn't get it working right until Shell Oil's patented atomized burner was implemented) Jumo 004s (at least early models) had to be started with gasoline (or similarly volatile fuels) to aid start-up as diesel or J2 jet fuel wouldn't atomize well when cold.

Metrovick had their own problems: "However, the F.2 engine suffered from a number of problems that cast doubts on its reliability. These were primarily due to hot spots building up on the turbine bearing and combustion chamber."..... as did later prototypes. The trouble with developing a totally new technology.

Also not a problem with the compressor (for the most part) but the same bottleneck as Whittle and Halford and ... all engines really: combustion and overheating. Metrovick solved it with a similar combination of tricks that Whittle and Halfor did: better turbine alloys and better combustion chambers in more foolproof external flame cans rather than an annular chamber.

That resulted in the reliable (and more powerful) F.2/3 of 1943 with 2700 lbf thrust (equivalent to the goblin I at production level thrust -or late prototype testing as the Vampire and XP-80 used). There was simply a lack of interest in pressing that design into mass production (I haven't seen definitive cost analysis comparisons to the Welland or Derwent -which were rather expensive engines too- but the realistic concerns may have been more to do with quality control and service maintenance with the relatively complex component-heavy Metrovick engines). So rather than readying that successful design for mass production, they simply moved onto the larger, more powerful F.2/4 along with turbofan and propfan arrangements. (which were all even more complex and less attractive for production than the earlier F.2/3)

Do note that the Goblin, an engine decisively LESS complex and easier to manufacture/maintain also suffered delays to mass production entirely due to limited funding/interest (or rather, near complete lack of funding outside of De Havilland's own private efforts). The Goblin was probably the most rational and conservative gas turbine engine design of the war (aside from maybe Ohain's) and in spite of Halfor'd later start than PowerJets/Whittle, the rapid progress could have led to earlier production with decisive government backing of the engine (and Vampire project).

Also note the Goblin was larger and heavier for any given thrust value than the wartime Derwent or (especially) post-war Nene and Derwent V. The same goes for the scaled-up Ghost (same thrust but 38% higher weight and 17% larger frontal area than the Nene, while the Goblin 3 suffered from similar weight discrepancy to the Derwent V -relative to their respective 3300 and 3500 lbf thrust- but wider area gap going between the 43" Derwent and 50" goblin -a 35% increase in area). The Utilitarian nature of the Goblin and Ghost did lend to being very reliable, easier to maintain, and less complex to manufacture, but from a purely technical standpoint they were decisively inferior to their Rolls Royce counterparts.

The HS 280 was initialy in advance but their insistance of using thoir own, even more complicated, engines delayed it until it was cancelled. Might have been a contender/alternative IF the Germans had gone for a cetrifugal jet engine.
The decision to go for the more complex (at the time) axial flwo killed their jet hopes, in fact it took until the early 50s that the west, with all their industrial might mastered the axial flow engine enough to match the centrifugal one.

Heinkel's engines were no more complicated/problematic than BMW or Jumo's (simplier in some ways, more complex in others) and were canceled well before their time and well before the He 280 was abandoned. (granted, the better of the two engines, the HeS 30 would have been an excellent fit for the Me 262 as well)

The He 280 was simply dropped due to being too limited in development potential than the Me 262 using the same engines. The ONLY engines being tested at the time better suited to the 280 than the 262 were the rather modest HeS 8 and even then it's somewhat arguable. (a particularly stripped-down Me 262 might have matched fairly well with ~1300 lbf thrust engines and been of greater use than the existing He 280 variations which were crippled by their limited fuel capacity -omitting fuel tankage, balast-armor, and some of the armament from the Me 262 should have been easier than redesigning the He 280 to carry more fuel -which would have made it heavier anyway)

The HeS 8 would have been a decent engine if it didn't hit so many unexpected delays (that its preceding HeS 3 and 6 did not) or had it been scaled up slightly ... still within Jumo 004 maximum diameter constraints. (the HeS 8 was trying to be a stand-in for the exceptionally compact HeS 30 and while still larger than that engine, managed to be smaller in frontal area than the 004, so a slightly larger original target size/weight could have made it more useful though still necessarily troubled by combustion problems due to the layout used -only way for Ohain to avoid that headache was sticking to the earlier HeS 6 directly and having Heinkel design an aircraft around 37-38" diameter engines ... engines that might realistically be mass produced by 1941, unlike all other options)

The Mig-15 did not suffer one lttle bit by using its Nene based engine vs the US's in the Korean war after all.

Actually it did. The Mig did well as a short/medium range interceptor with its smaller size and weight combined with good thrust compensating for larger fuselage (and overall less refined design) compared to the Saber. The MiG 15 could have never performed the majority of the Saber's missions due to lack of range and payload capabilities and a larger aircraft able to do so (using the same engine) would have suffered performance penalties.

The P-80 compared to F-84 shows some similar aspects, if not more dramatic given the very streamlined fuselage of the F-84 and particularly heavy weight. (making its speed advantage over the P-80 in level flight, using similar thrust even more impressive, though its lower rate of climb and long take-off run were obvious signs of the lower thrust to weight ratio) The F-84 also had a slightly thinner wing, but of larger area, not too different from the F-86 vs MiG 15 wings. (of course the F-80C was much more competitive with the F-84's range than the MiG vs Saber)

The MiG is a bit closer to the Gloster Meteor Mk.IV or 8 as far as massive thrust to weight ratio overcoming relatively high drag is concerned.

 

[Shortround6]

If you're not going to build the aircraft for fear of the engines, then cancel it and continue on with the B-17 and B-24 (smaller aircraft).

The USAAC (USAAF) requested a step foreward in range and load and the B-29 was their choice. It happens that the XB-19 most likely would have been chosen over the B-29 had it not been for project delays.

Interestingly enough, the XB-19 used the V-3420, which is the same engine the XB-39 (B-29 backup) used.

XB-19 pre-dates the B-29 by a number of years, The order was placed in Oct of 1935, the mock up inspected in March of 1936. Engine at the time was a 1600hp version of the V-3420. With increased defense spending the army actually got enough money to order a real airplane and Douglas went for the R-3350 engine even before that. Things had gotten so delayed that Douglas wanted out of the contract so their work force could concentrate on other projects (and Douglas was already loosing money on this project).
Army refused to cancel as they considered the XB-19 an engineering study that would gain knowledge for future projects , it was never a serous contender as a production aircraft. The state of the art in structural design had passed it by let alone aerodynamic knowledge.
The XB-19 was re-engined with V-3410 engines of 2400hp after being handed over to the Army.
The R-3350 engines in the XB-19 were a very early model that weighed around 300lbs less than the model that went in the production B-29s despite having a two speed supercharger instead of single speed (XB-19 didn't have turbos). Wright had gone back to the drawing board and built a new R-3350 that kept little more than the bore and stroke of the engines used in the B-19.

 

[stona]

You must be wary of cancelling designs willy-nilly. This sort of concentration is what led to the He 177 debacle for the RLM. On the other hand, for rather complicated reasons, the British did not concentrate their designs for different types into one type, though there were plans from time to time to do so, like the 'ideal bomber' programme which thankfully came to nought.

An example for fighters. In April 1939 the deadline for Scheme F meant that individual firms lacked the capacity to fulfil the RAF's requirements. 900 single seat fighters were required under the scheme. Production of the Hurricane would not start until 1937 and Hawker was expected to produce just 600 aircraft by April 1939. The shortfall was made up with a completely different aircraft and 310 Supermarine Spitfires were ordered. This meant that Britain would go to war with two single seat fighters when, in a perfect world, resources would have been concentrated on one. Concentration, in 1936, would have eliminated the Spitfire and Britain would have gone to war without the better fighter and the only one with realistic long term development potential.

An example for bombers. In 1936 none of the three heavies, Stirling, Halifax, Manchester had flown. The Air Ministry wanted to concentrate on one type but was fearful of eliminating a better aircraft. Production groups were established for all three. Had the Air Ministry not placed quality over quantity, and at considerable expense, then the least promising of the three, the Manchester, would have been an early elimination leaving the British without their best bomber of the war in the Lancaster.

With hindsight we can see that some unpromising or even failed designs could have been safely cancelled. The men who wanted to ditch the Lancaster had no way of knowing it would develop into something very different.

Cheers

Steve

 

[Shortround6]

Canceling the F4F and building F2As would have been a big mistake. The F2A gets it's good reputation from the early light versions.
Granted navy requirements porked it up a bit more than was necessary but the F2A was a small plane without a lot of growth in it. It would have hit a wall pretty soon in development no matter what.
The F2A-3 was over 1000lbs heavier empty than the XF2A-1 and export 239. The wing gained 172lbs while the airframe as a whole gained 280lbs. This is, in part, due to the powerplant gaining 547lbs. Early planes used engines with direct drive (prop turned same speed as the crankshaft) and single speed superchargers. Later engines (the 1100-1200hp ones) had reduction gears and two speed blowers, they also got propellers about 15in bigger in diameter. Fixed equipment also went up.

An R-1830 with two speed supercharger (not two stage) was about 80-120lbs heavier than the R-1820 used in the F2A-3.

The F2A actually had a rather small wing. While it was 208 sq/ft gross it was only 178 sq. ft. net due to the fat fuselage. This compares to the P-39 with a 213 sq/ft wing gross and 197 sq/ft net. Wing area goes from 97.7% of the P-39 to an actual 90% of the P-39 wing. You can only add so much "stuff" before the wing loading climbs to unacceptable levels.

Given the .50cal MG dislike of being synchronized you have a firepower problem (although not a big one) with two guns in the cowl and a gun in each wing compared to 4 guns in the wings. you are down 6-8 bullets per second total from the wing mounted guns. Sort of like having 3 1/2 guns instead of 4.
Going to six guns is never going to be an option with the F2A.
Maintenance on the F2A could be a real pain in the A**. It used a one piece wing.

Replacing major wing parts was not easy. Note that the landing gear was in wing.

 

[Shortround6]

"The R-2800 would be the obvious stop-gap for the Centaurus production delays as well as potentially displacing the Saber in general use as a 2000 HP class engine. (import over licensing still likely made more sense, if not more so due to the newer design and more dire war-time situation in the UK. (the R-2600 may have also been a consideration for supplementing Hercules supply, but given the relatively trouble-free history of that engine -and the R-2600's own problems at times- it's not a significant example where such considerations would have developed into genuine necessity) The R-2800 also developed substantially more during war-time, compared to the R-1830, so any licensed production would have been constantly playing catch up (or stuck making older, less powerful models) in a far less efficient or useful capacity than R-1830 production might. (even sticking with one of the 1200 HP single-stage variants -like what the Aussies ended up building- would have been useful for most/all needs of such an engine, particularly with maritime use -plus even the 2-stage variants didn't have the level of mechanical differences as the R-2800 A vs B vs C series which were largely entirely new engines given the level of changes made)


The R-1830, aside from the obvious fit to the Beaufort (and potentially any other Taurus powered production aircraft) would have made perfect sense on Gloster's F.5/34 monoplane and F.9/37 twin. (both likely taking much less modification than a Merlin refit would -the only other really viable 1000+ HP class engine of the period, and of course would compete for production with other Merlin powered types)"

They tried using R-2800s as a stop gap for the Centaurus in the Warwick bombers. It was too small. They did use R-2800s in the Ventura medium bombers.
Licensing is not always as easy it seems, for instance the British used forged cylinder heads in radial engines before the Americans did because the British couldn't make cast heads as well as the Americans could. Americans went to forged cylinder heads when the desired head designs could no longer be made economically with castings ( at an acceptable scrap rate). If you have to import or license the basic manufacturing technology in addition to the basic engine design things get a lot more complicated.
Even P & W could only work on so many engines at one time and P & W had decided that not only was the R-1535 (Taurus equivalent) a lost cause for development but that R & D was better spent on the R-2800 and R-4360 than trying for souped up R-1830s. Late R-1830s got trickle down improvements from the R-2800 and hit 1350hp for take-off. Had anybody really wanted them P & W also had the R-2000 for transport use in 1942 and perhaps it could have been used in patrol bombers.
The 1200hp two speed R-1830 engines went around 1450-1490lbs depending on exact model. While not prohibiting installation in some aircraft the smaller the aircraft the harder it is going to be to switch engines from a 1000-1100lb engine (Mercury), the 1300lb Taurus being a bit easier. A medium sized twin like the Beaufort being a little less sensitive to changes in weights and having the room to move things around to balance the engines. A Beaufort I was about 10,000lbs heavier loaded than a F.9/37 prototype.
And you may not gain a whole lot. The 1200hp R-1830 2 speed engine was rated at 1050hp at 13,100ft at 2700rpm Military power in the few versions that offered such a rating. It had 1200hp at 4900ft in low gear.

 

[stona]

As far as aero engine (and air frame) production in Britain was concerned, in 1938 it had come very much under government control. The huge investment in the firms and shadow industries by the government as the individual companies became reluctant, or simply refused, to invest anymore of their money gave the Air Ministry/Ministry of Aircraft Production this control. It was the MAP that told Gloster Aircraft that it would be building Hurricanes, not the parent company Hawker.
This resulted in the bulk of British wartime engine production being focused on just two engines. The concentration on the Rolls Royce Merlin (at the expense of the Exe, Vulture and soon Peregrine) and Bristol Hercules was possible, in a way that concentration on fewer air frames was not, as early as 1938/9. In April 1939 the Air Ministry asked Bristol and the shadow committee to erect two completely new factories to produce the as yet unproven Hercules engine. It was a sign of urgency as the war loomed that such a risk was accepted.
Incidentally Napier were only allowed to continue developing the Sabre because the Ministry was aware that the firm was on the point of pulling out of aero engine production altogether and, in Feeman's words, "it was a most unhealthy position for the Air Ministry to be dependent substantially on two firms only." With hindsight the Ministry made a mistake continuing the Sabre, but at the time more was at stake than just the technical promise of the engine itself. The contraction of the aero engine sector in the 1930s was a source of ongoing official anxiety and combined with the fundamental tenet that quality was maintained by competition, this is why Messrs Napier and their Sabre were saved.

 

[Shortround6]

The engine situation was blurry at best. While the Air Ministry may have wanted to save Napier they had no compunction about keeping Fairey and Alvis out. Armstrong-Siddeley had pretty much regulated themselves to 2nd tier without Air Ministry "help". Granted both Fairey and Alvis were more experimental shops than actual factories, and with a world wide empire standard engines make sense from a supply stand point rather than a multiplicity of overlapping types.
DeHavilland and Blackburn having the trainer market sewn up.
Alvis had invested in a "factory" to build Gnome-Rhone engines but it's capacity was about 10-15 engines a week which is laughable considering future needs and points out that the vast differences in what a "factory" or company could actually make. Factory A not being interchangeable with factory B.
Alvis did do important work in subcontracting and repair during the war with much expanded facilities. But even 100 R-1800s a month wouldn't have done much to change things and then you need to find some firm/s to handle the work that Alvis did do.

 

[stona]

Yes.
The structure of the groups was designed to allow Bristol's parent factory and Rolls Royce Derby (and to a limited extent RR Crewe which occupied a sort of intermediate position in the RR structure with no equivalent in the Bristol structure) to become, in Hive's words about Derby, "a huge development factory rather than a manufacturing plant."
The shadow plants were built and designed for mass production using unskilled labour. This applies to the two Bristol shadow factories and Bristol Accrington and to the RR plant at Glasgow, Ford Manchester and of course Packard across the pond. The British shadows obviously didn't have the research and development capabilities, or staff, of the parent companies, though what Packard got up to I don't know.

There were of course many other shadow factories producing components, the Air Ministry encouraged a minimum of 35% sub-contracting. Within a few miles of where I sit in Birmingham was a plant managed by Rover Aero producing engine parts for Bristol engines. It was previously a market garden and is now covered in the post war housing of Acock's Green!

Cheers

Steve

 

[stona]

I was revisiting "The Wooden Sword - the untold story of the gliders in WWII" by Lawrence Wright, which is a brilliant and sometimes very funny account of just that, when I came across something the Defiant would have been good at, had the need arisen.

Cheers

Steve

 

[Jugman]

The problem With the B-29 was NOT the fault of the R-3350 but, in fact, the engine nacelles. The cowling on the B-29 had very poor cooling characteristics and rather high drag. It was built up into a single unit that had to be removed as a single unit,This made any kind of maintenance task far more difficult than need be. All the "what ifs" that focus on changing the engines of the B-29 with a different model neglect this fact. It is not automatic the a different engine would bring a better installation with it.

Really the biggest problem the R-3350/B-29 faced is that it did not meet the deadline expectations of the bureaucrats and politicians at the top. Considering The hurried development schedule, the lack of proper flight testing etc. that the R-3350 went though it's really a wounder that the B-29 and R-3350 programs were not in far worse shape than they actually were.

 

[FLYBOYJ]

The problem With the B-29 was NOT the fault of the R-3350 but, in fact, the engine nacelles. The cowling on the B-29 had very poor cooling characteristics and rather high drag. It was built up into a single unit that had to be removed as a single unit,This made any kind of maintenance task far more difficult than need be.

Many aircraft of the period (and into the post war years) featured a "QEC" nacelle where the engine was changed as a single unit. I've seen Fifi up close and briefly worked around P-2Vs many years ago (3350s in a QEC unit) and I don't see any maintenance task made more difficult by this. If you have specifics, I'd like to hear about them.

Some QECs for comparison.

 

[FLYBOYJ]