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I think the point Garyt is making, is that towards the end of the war, the quality control was not the same as it was in the early years.
This has been seen in German aircraft as well, and due to similar circumstances. While the aircraft weren't "falling apart" after they were coming off the assembly line, the finish quality was not as as high as it could have been (or had been in earlier years), due to the rush.
Also, once in the field, they didn't have the luxury of a secure rear area to R&R the machines as was needed, but patched them up and sent them back out as best as they could. And unlike Europe, certain areas of South Pacific operations were extremely harsh on the aircraft due to the coral dust and humidity.
I think the point Garyt is making, is that towards the end of the war, the quality control was not the same as it was in the early years.
This has been seen in German aircraft as well, and due to similar circumstances. While the aircraft weren't "falling apart" after they were coming off the assembly line, the finish quality was not as as high as it could have been (or had been in earlier years), due to the rush.
I do recall reading somewhere, though I am not sure of the source, of landing gear failing upon the landing of a few late war Japanese planes, and this being blamed on the more quality and metallurgy of the late war Japanese aircraft industry.
Hayate1 codenamed 'Frank' by the Allies is generally regarded as the best Japanese fighter of the World War II period. Though Hayate was primarily used as a fighter it served in bomber capacity as well. Due to it's advanced direct-injection engine Hayate was able to outmaneuver and outclimb it's American counterparts, the P-47N Thunderbolt and the P-51H Mustang.
Ki-84 was not without problems. Due to the war time shortages and increasingly poorer quality control meant that Japanese pilots never knew how their plane was going to behave. For instance poor treatment of the high-strength steel meant that the landing gear could simply snap upon landing.
Several advanced models were introduced. Ki-84-II and Ki-106 were attempts to build the Hyate using wood as the steel shortages were extreme during the war. Ha-45 and Ha-44 were fitted with a 2,000 and 2,500 HP engine.
A total of 3,514 Hayates were produced. Used over China and Phillipines, in 1944-1945.
What difference does a G suit make? Does it make for example a sustained 7 G possible where it isnt without one.
If the alloying material has issues to start with then no matter how well you control the heat treat process, you'll have problems, and again all combatants had their share of issues with this.
I would think that the Japanese would have had problems with the alloying materials due to shortages caused by the strangulation of the Japanese economy by sub warfare. And I think they would have problems above and beyond any other major nations of WW2, the only ones in a remotely similar situation would be late war Germany (though not an island nation, so not the same), or Britain at the pinnacle of success of the U-Boat campaign, though Britain was not both strangled from sea at the same time it's production facilities were being intensely bombed. Or so at least I have read in different sources, broad-brush as they may be.
I think finding any true specifics on this though will be virtually impossible, at best a needle in the haystack type chase.
Heat treatment depends on chemical analysis and chemical analysis depends on some rare and difficult to obtain elements and quality control. Steelmaking has changed vastly in the postwar years. I doubt seriously that the japanese couldnt perform the heat treatment required, more likely they couldnt source rare alloying elements or due to shortage of fuels were obliged to accept "heats" that should have been rejected. A similar problem to the Me262 turbine blades, their failure could be blamed on incorrect heat treatment if you like, the real problem was Germany couldnt get the metals they wanted.
aircraft like the Ki 84 were still dangerous if flown by the right individual.
The landing gear was more likely mild steel, 4130 or 4140. Not to difficult to heat treat
Mild steel is very easy to heat treat, like I said if the Japanese were struggling for fuels and minerals the basic metal may well have been substandard, de slagging and refining of iron to steel can be termed "heat treatment". Even today companies in financial trouble have ended up on the rocks by cutting corners, "heat treatment" can become a cover all for general sub standard manufacture. Also in this era heat treatment was an extremely skilled job requiring years of training, temperatures were estimated by eyesight and there was no UT, RT and little DP and MP testing. I know nothing about this particular AC, just saying, on the other side many in the west had the opinion that Japanese couldnt make anything of quality so any failure would be blamed on that rather than just a hard landing.
And this brings us back to the pilot factor...
If the aircraft had marginal material quality but a good, experienced pilot, it may have held up well enough. However, you have an influx of inexperienced pilots being rushed through training and sent to the front and now that same aircraft will fail under the inexperience (hard landings, ground loops, improper proceedures, etc.).
So now the numbers of "failures" start climbing on the books and the fault may not lay entirely on the aircraft.
new and inexperienced pilots are hard on landing gear ... even ones in perfectly good working order.
Agree - the Japanese more than had enough skill and technology to heat treat mild steel which was used extensively in aircraft construction, not only in all metal aircraft but in fabric aircraft as well. 4130 steel tube was the basic frame work of most if not all fabric aircraft of the period. There's no exotic alloys in 4130 carbon steel - Carbon, Chromium, Manganese and Molybdenum if I remember correctly