There is no doubt that the Ma-102 was used in actual warfare.
However, it is true that there was a fear of self-destruction at temperatures above 200°C.
According to the documents in my possession, it is written that the use of bullets above 150°C is prohibited, and it seems that Ma-103 was used after the number of bullets that reached 150°C or higher.
(The specific number of bullets is unknown.)
For reference, it says that “Ma-101” (IAI) included in 7.7mm also self-destructs as well, so after 150 rounds, Ball was used instead of Ma-101.
Up to 150 rounds: AP, Ma-101, I
After 150 rounds: AP, Ball, I
(the T is not included because the I actually served a tracer function)
I haven’t heard that before. Samples of all 12.7mm rounds were captured and examined before war ended. At least one book also lists the usual recommended belt loadout. It was practically the same for all IJA aircraft guns: Special Incendiary / HE / AP-T. Sometimes AP-T was supplemented or replaced with HE-T if such excisted for the specific gun.
“Rough estimate”, but this is likely the best there is. Likely the demand was to produce equal amount of those four rounds. Not the faintest idea why snail dropped the fuzed HE round from Ho-103.
It’s quite interesting to see the development of HE round in US 50cals. The contemporary US design FA-T1 and FA-T2 resemble some features just like the Ma-103 and Ma-102. The latter just failed the cook-off test, with the round prone to self-detonate after 100 rounds burst.
As for M23, I think it should withstands more in the hot barrel, as a contemporary design to be used in the field, the round should have past “cook-off” test. The combat records showed 1000-2000 rounds be fired in a single mission without trouble.
It was also mentioned that the use of M23 round will decrease the cyclic rate of AN/M2 MG by 50 rps.
The explosive round is practically identical in construction to the M1 Incendiary.
The problem with this test is that it says a bullet was placed in the chamber after a burst.
But what about cooling?
Obviously an aircraft mounted gun is cooled by the airflow.
I don’t see how an M1 Incendiary wouldn’t cook-off under the same condition on the ground.
I don’t think that Tetryl would ignite earlier than flash powder when exposed to heat.
It’s kinda how they concluded that US self-sealing fuel tanks could survive even getting shot by .50cal bullets, yet they shot the tank directly and not with a bullet first impacting the duralumin skin of an aircraft, which would lead to bullet tumbling and much larger holes.
In later tests they found out that even holes from 20mm rounds could be sealed, when the round pierced the tank, but when a .50cal impacted the tank sideways it would rip the rubber apart, resulting in worse sealing.
So what I’m trying to say is that unless a test is carried out in the right condition, it’s not particular conclusive.
They said the standard M1 Inc could withstand the “cook-off” test, while the lead core version of it failed in the test.
Could it be that the Tetryl caused the failure? The explosive said to be ignited above 180 degree C.
It completely slipped away from me that I have to substract the projectile mass from the whole cartridge weight. Ki-44’s guns + spent cartridge + belt weight is 120kg, not 140kg. Not much of a difference though. I don’t think gaijin cares about the cartridge weight in the first place, though.
I was thinking back to this… shouldn’t it be the other way around? With a 4-blade prop, the synchronizer would try to fire the guns more often as it’d have more ‘gaps’ to do so, while with a 2-blade prop it’d be only twice per rotation - half as often.
The above figure shows the “Synchronous Cam Advancement Device” of the Ki-84.
The cam mountains are depicted in two.
This is only the case for the Ki-84 and does not apply to other 4-blade airframes.
It is not definite that there are two cam mountains with two blades, and with three blades, there will either be one or three cam mountains.
The answer is “it depends on the aircraft”.
Well, it doesn’t matter that much since the speed of the propeller is often much higher than the gun’s rate of fire to begin with.
In the case of the Ki-84, a reduction ratio of 0.5 for 3000 rpm results in 1500 rpm; in the case of the Ki-44-II, a reduction ratio of 0.6875 for 2650 rpm results in 1822 rpm.
i dont really want to fly more p38’s for the moment, maybe later, im much more interested in the different corsairs, at least you have fighting chance wtih them
