Maneuverability vs Speed

[yulzari]

The Hampden was considered so bad that it was taken out of action, even for night missions, by 1942.

The factories went over to making Handley Page Halifaxes. Not because the Hampden was so bad but because the Halifax was better. Ditto for the Whitley as Armstrong Whitworth factories changed to making Lancasters. Their peer Wellington did not stay in production through being better than the Hampden but because Vicker's factories were no readily convertible from their geodetic/fabric system to stressed skin sheet systems so they continued to churn out a pre war bomber until well after the war ended.

 

[SplitRz]

Well I didn't say it was a similar aircraft, but it was contemporaneous and also a twin engined bomber. I didn't make a point of comparing them in my initial post but SplitzRz challenged me to compare them so I did.

Mea Culpa!

 

[Just Schmidt]

Obviously, the sources for all are guilty of blending and mixing ferry range with combat radius, but whilst it clearly has an excellent range, there's nothing which appears to be superlative about the G4M and much which shows it at a disadvantage in terms of clunky/ ineffective defensive armament, propensity to burn, lightweight structure etc. It remains a good looking machine and without doubt, striking at long range and with surprise, it was a very effective weapon. But you don't keep surprising people with the same tactics. And there's a world of difference between lightning first strikes or making unmolested bombing raids on Chinese cities and the attrition of a long and opposed campaign.

I think wiki, while otherwise conforming with other data I know of, shortcahnges the Betty on range. While not a superplane, range was exceptional, though it certainly came at a cost. Mitsubishi wanted to use four engines, but the IJNAF turned them down.

But i do want to question the light weight structure. It is indisputable that it burned all too easily, but I have never encountered any actual explanation how the structure was leight weight, though it is often stated. It seem as if being Japanese in the mind of many translates into having a weak structure.

This is not hair splitting, rather I get tired of this trope being repeated over and over for pretty much all Japanese aircraft. I'm willing to learn, though, so i'd appreciate any factual information you may have on that point. Just because i haven't seen any evidence, dosn't mean it dossn't exist.

 

[Shortround6]

The factories went over to making Handley Page Halifaxes. Not because the Hampden was so bad but because the Halifax was better. Ditto for the Whitley as Armstrong Whitworth factories changed to making Lancasters. Their peer Wellington did not stay in production through being better than the Hampden but because Vicker's factories were no readily convertible from their geodetic/fabric system to stressed skin sheet systems so they continued to churn out a pre war bomber until well after the war ended.

Yes and because they stuck Hercules engines in them and upgraded enough parts to increase the gross weight considerably.
The Whitley had run into an aerodynamic dead end in 1939. You could hang Sabres off of the Whitley (although Whitley didn't deserve that punishment) and not get a fast bomber.
Hampden had some other operational limitations. Hard to put a turret in, limited size bomb bay crew space problems. Trying to turn a 22,500lb bomb into a 30,000lb bomber even with new engines?

 

[SplitRz]

Beaufighter didn't perform some of it's rolls until after it had been in combat for several years

Hey, Mr Bristol! Stop fighting, get baking!!!

 

[Shortround6]

I think wiki, while otherwise conforming with other data I know of, shortcahnges the Betty on range. While not a superplane, range was exceptional, though it certainly came at a cost. Mitsubishi wanted to use four engines, but the IJNAF turned them down.

But i do want to question the light weight structure. It is indisputable that it burned all too easily, but I have never encountered any actual explanation how the structure was leight weight, though it is often stated. It seem as if being Japanese in the mind of many translates into having a weak structure.

This is not hair splitting, rather I get tired of this trope being repeated over and over for pretty much all Japanese aircraft. I'm willing to learn, though, so i'd appreciate any factual information you may have on that point. Just because i haven't seen any evidence, dosn't mean it dossn't exist.

That is a good question and it may be very hard to answer. We can look at the empty weight of the aircraft and the size for some indications but not proof.

According to Francillon the G4M1 model 11 was 9500 kg empty, the G4M2 model 22 was 12,500kg empty as was the G4M3 model 34.

Maybe my math is off but the loaded weight of the G4M1 model 11 doesn't allow for the full rated capacity of the fuel, let alone oil and crew.

for a crappy comparison the B-25A was 8,129kg empty and the B-25C was 9,220kg empty but they had a smaller wing (about 15 shorter and 73% in size) and the fuselage was almost 10 ft shorter. We can try looking at engine weights and so on. US bomber strength varies quite a bit as some planes were allowed to decline as they got heavier with only local or critical parts strengthened

 

[Wild_Bill_Kelso]

Mea Culpa!

One has to be agile in these discussions, it comes from every direction at once.

 

[SplitRz]

I think wiki, while otherwise conforming with other data I know of, shortcahnges the Betty on range. While not a superplane, range was exceptional, though it certainly came at a cost. Mitsubishi wanted to use four engines, but the IJNAF turned them down.

But i do want to question the light weight structure. It is indisputable that it burned all too easily, but I have never encountered any actual explanation how the structure was leight weight, though it is often stated. It seem as if being Japanese in the mind of many translates into having a weak structure.

This is not hair splitting, rather I get tired of this trope being repeated over and over for pretty much all Japanese aircraft. I'm willing to learn, though, so i'd appreciate any factual information you may have on that point. Just because i haven't seen any evidence, dosn't mean it dossn't exist.

A light weight structure doesn't necessarily mean an inherently weak one as far as I understand (i'm not an engineer) - but it means it forgoing any extraneous weight including using the thinnest gauge / lightest materials possible. That means it might be perfectly strong enough in terms of performing its intended flight regime. Where it might become an issue in a combat however, is in the amount of 'redundancy' built into the structure. That might be perfectly acceptable under ordinary flight - but clearly becomes more critical when a bullet or lump of shrapnel passes through a structural member or you're hoping to survive a crash-landing. It also means potential less 'reserve' of strength in terms of metal fatigue (little understood at the time) or if the airframe became over-stressed in hard manoeuvres. It also meant in many Japanese aircraft forgoing things like self-sealing tanks, armour and other items for crew comfort etc.

And that's an important design criteria if you want good performance - especially range and manoeuvrability - from your available engine power. The unarmoured ultra light-weight aluminium pilots seat from a Zero posted earlier in this thread epitomises the approach of certain Japanese designers

Mitsubishi G4M: Why Betty Bombed

Mitsubishi’s G4M bomber went by many names, but perhaps the most appropriate would have been “flaming coffin.”

www.historynet.com

In order to achieve the G4M's great range and performance, he [Kiro Honjo] was forced to equip it with the largest possible fuel tanks and to forego rubberized self-sealing protection for them. Nor did he provide armor for the crew. (His friend Horikoshi seems to have taken the technique to heart in designing the Zero.) The Betty's wet wings were its tanks, with fuel cells neatly defined by the main spar and a secondary spar forward of it, the ends sealed by solid wing ribs. There was no self-sealing mechanism, which would have required a 1¼-inch-thick soft rubber layer weighing about 660 pounds, either inside or outside the fuel tanks, substantially reducing the tanks' capacity.

After 663 Bettys had been manufactured (some 2,400 would ultimately be built), Mitsubishi began to fireproof the wings by applying a thick self-sealing layer on the outside of the lower wing skins. This maintained the internal fuel capacity but adversely affected the airplane's aerodynamics. The rubber mat shaved about 6 mph from the G4M's speed and reduced range by almost 200 miles. Had they tried putting a matching mat on the exterior top of the wing tanks as well, the airplane probably would never have gotten off the ground.

The final version of the Betty, the G4M4, had an entirely new laminar-flow wing with integrally self-sealing fuel tanks. The benefits of laminar flow were probably illusory on Bettys, since IJNAS aircraft of all types had paint jobs that ranged from beater-bad to junkyard special, peeling and flaking in a manner that would have tripped any incipient laminar airflow. For years it was assumed that the Japanese simply didn't know how to make good paint, but the reason was even more basic. Mitsubishi aircraft were delivered to combat units in natural metal and spray-painted with camouflage in the field…without the benefit of primer.

The Betty was the product of excellent engineering pushed to the limit and then slightly beyond, to meet requirements created not by aviators but by military bureaucrats. Those procurement officers were aware of the airplane's main flaw but chose to accept it, dooming many crews.

The number of combat reports regarding the comparative fragility of many Japanese aircraft is pretty much legion. So trope or not, evidence seems to point towards it being accurate, at least for many types

Mitsubishi A6M Zero - Wikipedia

en.wikipedia.org

Every possible weight-saving measure was incorporated into the design. Most of the aircraft was built of a new top-secret aluminium alloy developed by Sumitomo Metal Industries in 1936. Called "extra super duralumin" (ESD), it was lighter, stronger and more ductile than other alloys (e.g. 24S alloy) used at the time, but was prone to corrosive attack, which made it brittle. This detrimental effect was countered with an anti-corrosion coating applied after fabrication. No armour protection was provided for the pilot, engine or other critical points of the aircraft, and self-sealing fuel tanks, which were becoming common among other combatants, were not used. This made the Zero lighter, more maneuverable, and one of the longest-ranged single-engine fighters of World War II, which made it capable of searching out an enemy hundreds of kilometres away, bringing it to battle, then returning to its base or aircraft carrier. However, that tradeoff in weight and construction also made it prone to catching fire and exploding when struck by enemy fire.

With its low-wing cantilever monoplane layout, retractable, wide-set conventional landing gear and enclosed cockpit, the Zero was one of the most modern carrier-based aircraft in the world at the time of its introduction. It had a fairly high-lift, low-speed wing with very low wing loading. This, combined with its light weight, resulted in a very low stalling speed of well below 60 kn (110 km/h; 69 mph). This was the main reason for its phenomenal maneuverability, allowing it to out-turn any Allied fighter of the time. Early models were fitted with servo tabs on the ailerons after pilots complained that control forces became too heavy at speeds above 300 kilometres per hour (190 mph). They were discontinued on later models after it was found that the lightened control forces were causing pilots to overstress the wings during vigorous maneuvers.

To quote our own GregP from 2012:

"The chief culprit in its fragility was the use of .032" Aluminum skin where the western powers used .040" or even .050" or even heavier. When everything is intact, the Zero is as strong as any western fighter. Once it gets battle damage it gets fragile, and the lack of self-sealing tanks and armor add to the perception of fragility."

 

[Wild_Bill_Kelso]

When comparing the Zero to the Spitfire, P-40, P-39, Bf 109, or Yak 1, keep in mind that any aircraft with a liquid cooled engine can be put out of action by a single bullet to the radiator, whereas fighters with air cooled engines like the A6M, Ki-43, F4F, F4U, Fw 190, La 5 etc. did not have this vulnerability.

A Zero could shoot down any of the liquid cooled engine fighters with it's 7.7 mm machine guns if they were well aimed. So in that respect it was actually less vulnerable.

I was unaware of the sheet metal thing, but Japanese sources describe the A6M as being pretty tough. It managed multiple intensive carrier landings. If you read the operational histories it was also not at all unusual for A6Ms to return to base with battle damage. Later A6Ms did have armor and SS tanks, though that came too late.

 

[Shortround6]

These figures are in the ballpark. However, I don't think anyone - certainly not me - claimed that the G4M was a state of the art design in 1941. I think there were definitely better bombers. The most advanced design for the Japanese was the A6M, and to a slightly lesser extent, the Ki-43 and the D3A. The G4M was a somewhat average design for the more advanced industrialized nations which had good range and reliability. What made it lethal was it's (for the time, pretty advanced) torpedo.

G4M compares quite well against most of the contemporaneous British twin engine bomber types - Hampden, Whitley, Wellington, Blenheim, and the Beaufort. The Blenheim (introduced 1937) and the Wellington were the most widely used, some Beauforts were used in the Pacific by the Aussies. Beaufort is a very close comparison to the G4M, Blenheim is slightly inferior - in particular because it couldn't carry a torpedo. Wellington has better range and bomb load but is very slow and was considered basically too vulnerable for daytime operations except far out to sea by the time G4M was available.

Just because something planes had twin engines doesn't mean they are comparable.
Whitley V grossed 33,000lb,
Blenheim IV grossed 14,500lbs.
Beaufort I was about 21,230lbs and by the way, had a service ceiling of 16,500ft In England, over the Owen Stanleys ???
G4M2 was about 10-15mph faster than Wellington III (Hercules engines) which was about 20mph faster than the Wellington IC (Pegasus) engines.

The G4M1 was pretty good design in 1940, trouble was it almost stuck in amber as fossil and not developed/improved at the rate that other planes were evolving to meet changing requirements. The Much improved G4M3 prototype didn't fly until Jan 1944 and production models didn't fly until late 1944.

 

[drgondog]

The foundation of structural analysis is to answer the question "will the design element, assy, airframe component major group, entire airframe survive the speciied applied load - before 'yielding' into permanent deformation. Next question is once into bend/yield mode, what next?

The primary reasons for airframe failures are two fold - but the dominant reason was that the 'load estimates and distributions Assumed, were in fact underestimated within the estimated design flight load envelope. The second reason involved not understanding failure modes. The latter conditions included flutter, aeroelasticity and fatigue - setting up unanticipated stresses.

As to 0.032 skin? Ok for pan head/button rivet, marginal for dimpling particularly heat treated sheet, and just a 'no' for countersunk flush rivets. The remaining shear area for a countersunk hole is extremely questionabl without rigid QA - and the spacing required for shear panel capability is pretty 'dense'... sometimes too much to offset the reduction in skin thickness weight of 0.040.

The structural engineers for airframe compamies were all pretty good. What was beyond the science and analytics were the airframe distortions under applied loads, as well as the science of predicting realistic aerodyamic loads even to a rigid body. That deficiency resulted in a very high percentage structural failure occurance well BELOW Limit Load analytics.

Even CFD today, unless coupled with structural models which will deform under applied loads, must be treated with caution. Folks in the business today like David Lednicer are far beyond my base of expertise in 1960s and 1970s

 

[SplitRz]

When comparing the Zero to the Spitfire, P-40, P-39, Bf 109, or Yak 1, keep in mind that any aircraft with a liquid cooled engine can be put out of action by a single bullet to the radiator, whereas fighters with air cooled engines like the A6M, Ki-43, F4F, F4U, Fw 190, La 5 etc. did not have this vulnerability.

A Zero could shoot down any of the liquid cooled engine fighters with it's 7.7 mm machine guns if they were well aimed. So in that respect it was actually less vulnerable.

I was unaware of the sheet metal thing, but Japanese sources describe the A6M as being pretty tough. It managed multiple intensive carrier landings. If you read the operational histories it was also not at all unusual for A6Ms to return to base with battle damage. Later A6Ms did have armor and SS tanks, though that came too late.

Re the radial engine trope.

This is one of the most enduring and questionable 'accepted wisdoms' that I too once believed. As a 20 something, I met and spoke to decorated FAA pilot John Blunden at some length on this subject. He'd flown both the Fairey Firefly and Hawker Fury in combat in Korea. I casually pondered why it was that the Fireflies were tasked more dangerous ground attack missions and not the Furies with their (as I supposed) more resilient radial engines.

He told me that the radiator is a very small target (and in the light of your comment Bill, not even visible to an aircraft attacking its victim from behind, so how are they even going to see it, let alone going to aim at it or hit it with 7.7s?!) - and was usually protected with armour, as well as being physically shielded about and behind from the structure of the aircraft and the engine itself. He also snorted with amusement and said that a radial engine is both a larger target to aim at than an inline for the people on the ground taking pot-shots (which is something I also have read regarding gunners aiming at 190s attacking B17s) and being bigger, even if there weren't cooling lines going into it, there were plenty of fuel and oil pipes just as likely to get hit and bu&&ered and cause an engine failure as on an inline which had a much small frontal profile, even including the radiator.

Besides all, if you were really in such an advantageous position as to aim at a radiator, why wouldn't you instead be firing through the unarmoured sides of the cockpit or canopy to take the pilot out?

The subject has cropped up several times elsewhere too and no one ever seems to have been able to resolve the evidence in favour of the radial. It would seem odd, if its really true, that IL2s, the most wisely used ground attack aircraft of the war, were never equipped with a radial engine, given the environment in which they operated (The Russians had them, afterall). And also on the western front, given the Hawker Typhoons were operating with an inline engine of already tainted reliability, there should have been a marked and measurable difference of loss and attrition between them and the P47s performing a very similar mission.

I summon the Myth Busters on this one!

 

[Shortround6]

When comparing the Zero to the Spitfire, P-40, P-39, Bf 109, or Yak 1, keep in mind that any aircraft with a liquid cooled engine can be put out of action by a single bullet to the radiator, whereas fighters with air cooled engines like the A6M, Ki-43, F4F, F4U, Fw 190, La 5 etc. did not have this vulnerability.

Any plane, regardless of engine cooling type, could be put down with a bullet to the oil cooler or lower part of the oil tank. The only difference is size of vulnerable area. Leaving the pilot out of this for now. Single bullet into the lower part of an unprotected fuel tank may mean a forced landing dozens of miles short of the home field.
Liquid cooled fighters were brought down with single bullets. One does wonder about the actual percentage.

A Zero could shoot down any of the liquid cooled engine fighters with it's 7.7 mm machine guns if they were well aimed. So in that respect it was actually less vulnerable.

Well, a Hurricane with "well aimed" eight 7.7mm machineguns firing 160 rounds per second would turn a Zero into a colander compared to the Zero firing about 26 rounds per second.

 

[drgondog]

The other 'impossible' conditions related to airframe failures - were airframes asked to carry mor, fly farther, accept bigger engines - all with minimum 'pause' to reflect on exactly how the new missions affected flight safety - and redsign to solve.Realistically, such resulted in placard insructions to "Don't do that, or this and for god's sake - the Other'. Most rare indeed were opportunities to completely redesign a successful aircraft and make it better suited for all the missions the predecessor was called to perform - like the P-51H.

 

[Wild_Bill_Kelso]

Re the radial engine trope.

This is one of the most enduring and questionable 'accepted wisdoms' that I too once believed. As a 20 something, I met and spoke to decorated FAA pilot John Blunden at some length on this subject. He'd flown both the Fairey Firefly and Hawker Fury in combat in Korea. I casually pondered why it was that the Fireflies were tasked more dangerous ground attack missions and not the Furies with their (as I supposed) more resilient radial engines.

He told me that the radiator is a very small target (and in the light of your comment Bill, not even visible to an aircraft attacking its victim from behind, so how are they even going to see it, let alone going to aim at it or hit it with 7.7s?!) - and was usually protected with armour, as well as being physically shielded about and behind from the structure of the aircraft and the engine itself. He also snorted with amusement and said that a radial engine is both a larger target to aim at than an inline for the people on the ground taking pot-shots (which is something I also have read regarding gunners aiming at 190s attacking B17s) and being bigger, even if there weren't cooling lines going into it, there were plenty of fuel and oil pipes just as likely to get hit and bu&&ered and cause an engine failure as on an inline which had a much small frontal profile, even including the radiator.

Again, I get most of my perceptions or "value judgements" on these matters directly from the operational histories and the interviews and memoirs of operational aircrew, i.e. mainly pilots.

I don't think this is a trope, and once again, I do not appreciate being baselessly accused of spreading tropes.

Whether or not a radiator is a small target depends on the layout of the radiator and cooling systems. If the cooling systems are concentrated in the nose, it is a relatively small target. If the cooling systems extend into the wings, as they were in many aircraft, it is a bigger target.

The Ki-43 and A6M pilots in particular emphasized shooting into the radiators and cockpits of Allied fighters. They had specific techniques for doing it, for example, A6M pilots would pull into a tight loop, which no Allied fighter could follow. As the Allied fighter stalled out, the A6M pilot would continue the loop, while slipping with the rudder, and shoot into the nose of the Allied fighter from above. The Japanese called this "Hineri Komi"

Hineri-komi - Wikipedia

en.wikipedia.org

This was not the only means by which this was done. Japanese fighters generally had a better rate of climb, especially at lower altitudes, than Allied fighters, and they were often able to attack from above, or during tight turns while pulling lead.

What is more, Allied pilots commented on the issue of radiator vulnerability as well. When the P-51A was introduced into China, 23rd Fighter Group leadership was very impressed with it's speed. But they found several small problems, one of which was the greater vulnerability of the radiator, both to ground fire and to fighters. The P-51A took greater losses in that theater than the older, slower and less sophisticated P-40 - which had the radiator plumbing concentrated in the nose.

Besides all, if you were really in such an advantageous position as to aim at a radiator, why wouldn't you instead be firing through the unarmoured sides of the cockpit or canopy to take the pilot out?

They generally attempted to do that as well, spraying the cone of bullets into the 'nose', from what Saburo Sakai and others described. This is also what was done by Hans Joseph Marseille in North Africa against P-40s and Hurricanes.

The subject has cropped up several times elsewhere too and no one ever seems to have been able to resolve the evidence in favour of the radial. It would seem odd, if its really true, that IL2s, the most wisely used ground attack aircraft of the war, were never equipped with a radial engine, given the environment in which they operated (The Russians had them, afterall). And also on the western front, given the Hawker Typhoons were operating with an inline engine of already tainted reliability, there should have been a marked and measurable difference of loss and attrition between them and the P47s performing a very similar mission.

I summon the Myth Busters on this one!

The Il-2, you might want to notice, had an armored 'bathtub' protecting the whole engine and pilot area (though not the poor gunner). I think the Typhoons got some engine / radiator armor too when they started using them for ground attack (greatly increasing their weight to overall detriment)

 

[Wild_Bill_Kelso]

Any plane, regardless of engine cooling type, could be put down with a bullet to the oil cooler or lower part of the oil tank. The only difference is size of vulnerable area. Leaving the pilot out of this for now. Single bullet into the lower part of an unprotected fuel tank may mean a forced landing dozens of miles short of the home field.
Liquid cooled fighters were brought down with single bullets. One does wonder about the actual percentage.

It was apparently enough to notice, but not enough to stop using them...

Well, a Hurricane with "well aimed" eight 7.7mm machineguns firing 160 rounds per second would turn a Zero into a colander compared to the Zero firing about 26 rounds per second.

I don't disagree. But another advantage of those 20mm is that they had greater range. Would you want to go head to head with a Zero in a Hurricane?

 

[BarnOwlLover]

Problem with the original 20mm Oerlikon MGFF (as used by Germany in the Me 109E and formed the basis of the early Type 99 Model 1 cannons) is that they fired low velocity shells, which were a poor ballistic match for the 109's 7.92mm MG 17s and the Zero's .303 Vickers guns. If anything, those 20mm cannons had shorter range and worse accuracy than the rifle caliber MGs. Reportedly, some German pilots admitted that they would've rather had like 4x .50 Brownings instead of the mix of 7.92s and 20mms in the Battle of Britain.

 

[Shortround6]

There is a picture of a long nose Allison on page 131 "Vees for Victory" of Captain Eddie Rickenbacker looking at an Allison C-15 that had been returned from North Africa with 14 bullet holes in the engine and getting back to base. No mention of how many minutes or miles that was which is rather important in figuring out effects of battle damage. Do you have 2 minutes after such and such happens or 15 minutes.................or 30 minutes.

I am kind of impressed but I note that they didn't try to repair the engine but rather shipped it back to the US from North Africa probably around the Cape of Good Hope. engineering study or propaganda?

 

[Wild_Bill_Kelso]

There is a picture of a long nose Allison on page 131 "Vees for Victory" of Captain Eddie Rickenbacker looking at an Allison C-15 that had been returned from North Africa with 14 bullet holes in the engine and getting back to base. No mention of how many minutes or miles that was which is rather important in figuring out effects of battle damage. Do you have 2 minutes after such and such happens or 15 minutes.................or 30 minutes.

I am kind of impressed but I note that they didn't try to repair the engine but rather shipped it back to the US from North Africa probably around the Cape of Good Hope. engineering study or propaganda?

He may have landed 'dead stick' too, which wasn't unusual, though from what you said it sounds like they were implying the engine kept running...

 

[Wild_Bill_Kelso]

Problem with the original 20mm Oerlikon MGFF (as used by Germany in the Me 109E and formed the basis of the early Type 99 Model 1 cannons) is that they fired low velocity shells, which were a poor ballistic match for the 109's 7.92mm MG 17s and the Zero's .303 Vickers guns. If anything, those 20mm cannons had shorter range and worse accuracy than the rifle caliber MGs. Reportedly, some German pilots admitted that they would've rather had like 4x .50 Brownings instead of the mix of 7.92s and 20mms in the Battle of Britain.

I stand corrected. 20mm cannon still does a lot more damage though right?