If you are referring to “Informational Intelligence Summary No. 85 – Flight Characteristics of the Japanese Zero Fighter” (December 1942), you might want to carefully re-read the document. It clearly sets forth the instances were the A6M2 was found to be superior and where it was deficient. The report points to the previously identified (September 1942) rapid fall off of maneuvering ability as the A6M2 approaches 300 knots and the engine cut-out under conditions of negative Gs.
The document is US government and no longer classified (de-classified in 195
and as such is in the public domain. In fact, you can find a copy already posted on the internet at:
http://www.warbirdforum.com/diego.pdf
The propeller on the A6M2 #4593 was the original. One blade was slightly damaged in the crash and was repaired. The “replacement” of the propeller is one of the recurring myths surrounding the restoration of # 4593. It is usually trotted out to try to explain away any performance failings. Oddly enough, had the Navy replaced the original, they would have used a Hamilton constant speed type which was essentially identical to the original.
Here is a narrative from a USN fighter pilot, an F4F ace with 2 A6M2s to his credit, who flew this aircraft in September and October of 1944:
“I first saw the captured Zero as a pile of salvage shortly after it arrived from Alaska. Soon after I was sent to the Southwest Pacific and didn’t see the plane again until August 1944 while I was assigned as fighter training officer at ComFAirWest at San Diego.
“The Zero had gone to Tactical Air Intelligence Center and was based at Anacostia Naval Air Station, near Washington, D.C. After Sanders, Hoffman, and others tested, compared, and evaluated the airplane, the Army put it though similar paces.
“While fighter training officer at San Diego, I learned that Koga’s Zero was still at Anacostia, airworthy, but unused. I arranged for it to be flown to San Diego. The Zero 21 was a mighty sweet machine, even in its superannuated. The refined aerodynamic design was not compromised by mass production. Fit and finish of all plates, rivets, the close and accurate fit of fairings, engine cowl, access plates, canopy, and wheel doors were most faithfully executed.
“The propeller spinner faired into a cowling that smoothed the contours of the reduction gear housing of the engine. The interior aerodynamics of the engine cowling permitted the adequate cooling of the two-row 14-cylinder engine with a remarkably small intake. Contrast that with the inlet on the F4F-3 and -4 which originally came with a spinner but had to sacrifice it to cure engine overheat problems. The Sakae engine looked and sounded much like our R-1830. It ran smoothly and cool. Displacement was somewhat less that the Pratt and Whitney 1839, but its 1130 hp was smoother and adequate. It was not supercharged as extremely as the R-1830-76/86 and at very high altitude (over 30,000 feet) compared very poorly with the Pratt and Whitney. But we hardly ever encountered Zeros above 10,000 feet with our F4F-3s and -4s, so we were carrying supercharger hardware as extra baggage. The F4F, which became the FM-2, was re-engined with the Wright R-1820 with about the same power as the R-1830, but much less supercharger. This was a better machine to fight Zeros with, but we didn’t get in squadrons until 1944, and by that time the Zero was no the problem it had been in the beginning.
“By the time I was flying the Zero 21 it may have had some of its automatic systems disabled. An example is the automatic altitude compensation of carburetor mixture. The first time I went for altitude the engine began to cut up disgracefully above 5000 feet. Worried that the engine was giving up, mixture came to mind. On this machine full rich is a rearward position of the mixture control. Manual leaning comes by easing this control forward. On doing this gingerly the engine smoothed up beautifully and the airplane jumped ahead with about 500 more horses - no less.
“The propeller was auto hydraulic *** Hamilton – no mysteries. We ran the engine as though it was an R-1830, but did not let the RPM go over 2600.
“The case of the manifold pressure gauge had been cracked n the crash at Akutan and it leaked. It was left in the instrument panel, but we used a standard AN type attached to a bracket nearby.
“The throttle sat in a quadrant outboard of the mixture control. It was shaped like the handle of a knife – complete with wood side plates for contour. It was about five inches long and on the top had a switch to be operated by the left thumb. This switch was for cutting in or out the 20mm cannon.
“The Zero carried many rounds of 7.7mm for the two fuselage guns and only 80 to 100 for each of the 20mm wing guns. Ergo, sight in with the 7.7 then cut in the two 20s for telling shots. I dimly remember there was a trigger lever you could pull up and squeeze on the front edge of the throttle. If you were not in combat, this lever would drop down where inadvertent firing was precluded (we had sad events because the trigger on the stick of U.S. fighters was easily squeezed in excitement).
“Cockpit was not so tidy as the F4F, but easily as tidy as the F4U and earlier Vought birds. Instruments were much like ours, but metric for pressures, temperatures, [and] altitude. Airspeed was in knots. It had an inner and outer scale as the needle needed to go around about 1½ circles to get to the high end of the scale.
“In the Zero 52 there was an exhaust temperature gauge as well as the usual cylinder head temperature gauge. My guess is that it was a refinement to fine tune the mixture to get the remarkable endurance and range the Zero was famous for.
“Gyro horizon had a sky blue upper half like some of the German WWII instruments I have seen. To the envy of every F4F pilot, the landing gear was hydraulically actuated!
"Tail wheel was fully retracted behind tight doors. Tail hook was faired into a recess along the keel. The hook was hinged on the end of its strut, latched in the snatch position to catch the wire then dumped, so the Zero could taxi forward over other wired unimpeded. I understand we toyed with this idea but gave it up because of worries it might misbehave and cause an unarrested landing.
“Brakes were hydraulic – weak. The wide tread and relatively low landing speed favored weak brakes so you might say they were adequate. Rudder bar was center-pivoted with stirrups for each foot. Brakes were actuated by a hand lever; rudder angle determined which wheel received braking action.
“The canopy gave a beautiful view of the outside world, noticeably good to the rear in contrast to our VF’s. The enclosure was made up of many panes of plexi, some contoured. Wind noise was moderate. Some of the enclosure had been destroyed and was remade by A and R.
“The windscreen section was original, for it bore deep craters from the corrosion that took place during its dip into the marsh of Akutan. These cavities had a way of coming into focus when air speeds built up. I often wondered why they had not been replaced by A and R. In VF-42 we had some nasty experiences with the original F4F windscreens blowing out on use when flying at more that 300 knots. Grumman corrected it with a beef-up that robbed us of valuable forward vision, but it ended the problem. The Zero had no such heavy structure in the first place, so it was a source of uneasiness.
“The Zero 21 had no primer for engine starting. The carburetor has a large capacity acceleration pump you feel when you moved the throttle. To start, you had the mechanic wind up the inertia starter as you wobbled up fuel pressure and work the throttle two or three times to spray in the discharge of the accelerator pump. On contact the engine rolled over readily, caught, and picked up to run without complaint.
“The carburetor barrel has an oil jacket through which circulated lube oil to combat any tendency to form ice. I’m not sure whether it was always in action of selectable from the cockpit. We never touched it as I remember. Seems a tidy way to handle ice.
“In February-March 1945 I has a dandy low-time fresh-caught Zero 52 to fly. It was much like Koga’s Model 21, but heavier because of two more 20mm guns. It had a hundred or so more horses, and ejection type exhaust stakes, but flew essentially like the Model 21 – very sweet.”
I’d suggest a look at Jim Reardon’s “Koga Zero”. There’s a couple of other reports wandering around if you know where to look, such as Lt Cdr Eddie Sanders’ initial evaluation “Report for Flight Test Officer – 29 September 1942” (and duplicated within the “Enemy Material Report, No 71 – Headquarters, Allied Air Forces South West Pacific Area Directorate of Intelligence”) and “Technical Aviation Intelligence Brief No. 3” (4 November 1942). There is also another report from 4 September 1942, “Informational Intelligence Summary No. 59 – The Japanese Zero Fighter” that is a compilation of information based on examination of crashed aircraft from various locations and issued some 16 days before the A6M2 # 4593 was first flown by Sanders.
FWIW, the Sanders report fully describes the propeller: “The propeller is a hydraulically operated constant speed 3-blade design, 9’6” in diameter, much like ours with many parts interchangeable.” Intelligence Summary No. 59 also describes the propeller used on the A6M2 and corroborates the statements of Sanders and the gent who flew the plane in 1944: “The propeller is a 3-blade, constant speed Sumitomo of the hydraulic type, and apparently identical with the Hamilton model.”
Regards,
Rich
) the US fighters sent for comparison were in mint conditions.
, you probably have an airplane that can match the opponents in 43-44 
Linear Mode
