"Stretch or not strech" of aircraft designs

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The German Heinkel and Dornier bombers were stretched. The versions flown in the Mid Thirties evolved significantly into the 40's.
 
In many cases the chance to improve performance was given up simply to get more planes. The planned development of the Spitfire and the actual production were almost strangers to each other.
That's a good point and one that I only recently came to realize. I've often thought" why didn't they make this improvement or that" but I guess it was better to have enough good planes than not enough great ones.
 
Interesting.
I knew the Hellcat and Bearcat shared the R2800 and that it wasn't the same model R2800. I should have typed a bit more.

I didn't realize the Tempest and Sea Fury shared much of anything.

The Bearcat used a single stage, two speed "C" series R-2800 (actually at least 3 different engines were used in Bearcats, the F8F-2 used an "E" series engine) While the Hellcat used the two stage B series engines. The C series engines used cylinders and heads with much more finning than the B series engines which allowed them to make more power without overheating or to make the same power with about 10% less cooling air flowing through the cowling (less drag) they also used different pistons, connecting rods, crankshafts, crankcases, reduction gears, and so on.
The Bearcat, aside from looking short and pudgy like many Grumman products, shared no common parts, was not scaled down in anyway from the F6F and had nothing to do with the F6F design.

On the Fury, from Wiki so take as you wish.

Developed as the "Tempest Light Fighter (Centaurus)", the semi-elliptical wing of the Tempest was incorporated, but was shortened in span by eliminating the central bay of the wing centre-section, the inner part of the undercarriage wells now extending almost to the aircraft centreline, instead of being situated level with the fuselage sides.[3][4][5] The fuselage was broadly similar in form to that of the Tempest, but was a fully monocoque structure, while the cockpit level was higher, affording the pilot better all-round visibility
 
That's a good point and one that I only recently came to realize. I've often thought" why didn't they make this improvement or that" but I guess it was better to have enough good planes than not enough great ones.
Towards 1944 it was sometimes preferable to have more planes now rather than better planes after D-Day for example. The Typhoon and Lancaster were two that I can think of where more was seen as preferable to fewer but better later.
 
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Here we have some extremes on the definition of "stretch" The P-47 didn't change more than couple of inches in any dimension until you got to the N and those few inches (if the change existed at all) was due to changing the propeller. Yet the fuel capacity (internal) went up 21%, the engine power went up 25% and external loads drastically changed. The N used a bigger wing wing to house even more fuel and it's engine was 40% more powerful than the early P-47. BTW the early P-47 only had a relatively small amount of fuel compared to what it would later carry using drop tanks. The early P-47 carried over 2 1/2 times as much fuel as an early Spitfire or 109 and around twice as much as an early Fw 190.

The Fw190 to TA152 was one of, if not the most extreme, cases of actual physical change in dimensions of aircraft design for single engine fighters. Little of the change had to do with increased armament.
 
The German Heinkel and Dornier bombers were stretched. The versions flown in the Mid Thirties evolved significantly into the 40's.

While the capabilities (gross weight and power) of the He 111 were stretched the actual aircraft was not, yes it got a new nose and they straightened out the wing leading edge but a 1937 and a 1943 HE 111 were pretty much the same sized aircraft.
The Dornier Do 217 was a not quite clean sheet of paper aircraft compared to the Do 17. Similar configuration and shape but no actual interchangeable parts aside from hardware.
Max gross weight of the later 217s being almost double that of a Do 17Z-2.

Many planes got new engines or more powerful versions of existing engines, they changed armament, they changed cockpits or noses (on twins) and they got heavier, sometimes much heavier. All without changing the basic external shape and size. So what do we consider "stretch". Changing the external dimensions to any great extent (not bolting on different wing tips like the Spitfire) was much rarer.
 
I'm not sure it's germane here, but I always thought that one of the most successful stretches of an aircraft was a C-141A to a C-141B. That really opened up a whole different world of mission effectiveness for that airframe.

When I read the OP thread title, that was what came to mind at first.
 

I'd say that Do-217 was a clean sheet design.
 
Why did they not develop the A6M Zero further to be competitive?
Besides the overburdened engineering staff and the less than optimum fuel, there just didn't seem to be available significantly more powerful engines of the necessary reliability and power-to-weight ratio to go with A6M's ultralight design philosophy. Any serious upgrading would require serious beefing up of the airframe, which brings into question the feasibility of a quick production change over. Any attempt to improve combat survivability would doom the ultralight philosophy entirely as well as any hopes for a quick change over.
Time for a clean sheet of paper.
Cheers,
Wes
 
The Japanese never completely gave up on their lightweight design philosophy, so that one can doubt if their presumably excellent late-war fighters could compete with sturdily build American fighters in high speed ACM.
 
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The Japanese never completely gave up on their lightweight design philosophy, so that one can doubt if their presumably excellent late-war fighters could compete with sturdily build American fighters in high speed ACM.
By most accounts they did, though handicapped by undertrained pilots, lower grade fuel, and overwhelming opposition.
Still, the ultralight design approach seems to naturally be handicapped in the growth department compared to the "sturdily built" design philosophy. Also, it appears Japan put a much smaller portion of their resources into aeronautical research and development than did the US, UK, and Germany. The Japanese penchant for the "sudden offensive strike" and "single decisive battle" tended not to favor long term thinking, nor did their impending resource crisis.
Cheers,
Wes
 
The Japanese never completely gave up on their lightweight design philosophy, so that one can doubt if their presumably excellent late-war fighters could compete with sturdily build American fighters in high speed ACM.

Hello Spicmart,

I would have to agree with X XBe02Drvr here. The late war Japanese fighters actually appear to be quite competitive except for build quality, reliability and pilot quality. Even their best engines were not quite keeping up with what was available to American designers, but from a performance standpoint, they were near even at low to medium altitudes.
The design philosophies were still a bit different though: American aircraft tended to be very well protected. With few exceptions such as the Ki 61, Japanese aircraft were not. Some carried very minimal armour such as a sheet behind the pilot. Some such as the N1K2-J were just sturdily built but carried no actual armour at all.
Another inconvenience was the need to carry substantial amounts of Water-Methanol for anti detonant because the fuel was poor quality and ADI was needed to use anything past cruise settings.

With the A6M, I believe they had a suitable replacement pretty early: the Kinsei / Ha 112 but for some reason decided not to attempt a conversion until the war was nearly over. I believe it was even considered for the initial design for the A6M but eventually the Zuisei was chosen for the prototype and then replaced by Sakae in production models.
The conversion to Ha 112 / Kinsei would have required some armament considerations though. It required the deletion of the cowl armament and without that, the A6M2 and early A6M3 would have had no staying power with just 60 rounds per wing cannon and no other guns.

- Ivan.
 
With the A6M, I believe they had a suitable replacement pretty early: the Kinsei / Ha 112 but for some reason decided not to attempt a conversion until the war was nearly over.
I think that reason may have been that the Kinsei didn't reliably develop enough additional horsepower to offset its greater weight until late in the war.
In the array of missed opportunities for stretchable aircraft, there hides the ill-fated Gloster F.5/34, often accused of paternity in the case of the A6M, and which died too young to even be christened with a name. The Hurricane and Spitfire beat it to the production line, so it was dropped. But looking at the numbers, if it had hung around long enough for its puny 840 horse radial to be replaced with one of the 1000 or 1100 hp types that showed up soon after, it might have been a useful item in the war to come. With its generous wing area and light wing loading, plus its typical Gloster rugged construction, it looks like an airframe with plenty of growth potential. Perhaps it could have been doing the Typhoon's job before the Typhoon made it out the factory door. Or maybe it could have given the Fleet Air Arm the high performance fighter that it so painfully lacked. We'll never know.
Cheers,
Wes
 
Hello X XBe02Drvr ,

I had never looked at the Gloster F.5/34 in detail before. It does look interesting from a technical point of view.
It is running a bit less power but has about the same performance as a Hurricane. I wonder what would have happened if they had cleaned up that semi-retractable main gear. That should have improved things.
Sounds like these guys just had some bad timing and were a little late to the party.

Regarding Kinsei as a replacement for Sakae, I believe this is a bit of a judgment call. By 1942, it was already making 1300 HP (Take-Off) and 1100 HP at 20,000 feet as installed in the D3A dive bomber as compared to the single speed Sakae 12 that was in service in the A6M2. Even the A6M3 / A6M5 with 1130 HP at Take-Off and 980 HP at 6,000 meters wasn't doing quite as well.
Is the extra power worth the extra weight and having to redesign the armament package? That is really the judgment call.

- Ivan.
 
Hello Ivan. Good question, isn't it? I think the tiebreaker here is reliability, which, IIRC, was something of an issue with the higher powered versions of the Kinsei. Too bad we can't rewrite history.
Cheers,
Wes

Hello XBe02Drvr,

In this case, with Kinsei engines already being installed in the D3A2, I don't think it was necessary a reliability issue though these were also not particularly high powered engines either.
I suspect (!) it had more to do with the strategic situation at the time.
Keep in mind that this is when the brand new A6M3 Model 32 was coming out.
In theory it was a hotter aeroplane with a two speed supercharger and more power and speed.
The problems were that it was a heavier aeroplane and not quite as agile at low altitude AND that it had an engine that consumed more fuel. The extra space of the engine cost some of the fuselage tank capacity, so it didn't have the range.
The Guadalcanal campaign was being fought from Rabaul and the new Model 32 could not fly that far.
The bigger Kinsei would probably have just made things worse at THAT time.
Up to that point, the only wing armament was a couple Type 99-I cannon with 60 round drum magazines with a total firing time of about 7 seconds. Magazine capacity was increased shortly after, but additional wing armament didn't come along until the A6M5 series quite a bit later.
I believe that carrying more fuel as was done in the A6M3 Model 22 or perhaps using a larger drop tank was easier to work out than revising the wing armament to address the loss of cowl guns.

- Ivan.
 

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