issue with Ho-103 machine guns? Ki-84, A6M5b?

[Krusty]

Is there a discrepency with Aces High's Ho-103 gun rate of fire?

I've been reading about the Terrible performance of the Ho-103 machine gun in Japanese service. Specifically, I was interested because of how the Ki-43 had one gun and then one much more reliable 7mm MG. Not only was the gun liable to jam or explode at first, but it was slow. Very slow. A combination of the Browning design and the Japanese synchronization gear, the gun reportedly only had a rate in the range of 400-450 rpm give or take. This was the very real reason why the Japanese pilots preferred the 7mm MGs so long into the war.

That made me wonder... The Ho-103 was common, right? You find it on our Ki-61 as well, but this is outside of the sync area, and fires unhindered from the wings. Doing an AH test gives roughly 882 rpm for those wing guns. Not bad.

I was thinking about the earlier versions of the Ki-61 that had the 4x 12.7mm guns or the MG151/20 in the wings and the 12.7m in the nose. I was thinking about how they would suffer the same problems with sync on this configuration.

Then I realized our Ki-84 has this same gun in the nose. At an in-game test that shows ~945rpm. Surely this is the unsynchronized rate, firing through the prop? That can't be right? Should it not be even slower than the unsynch'ed rate of the Ki-61? That seems to be the most high-end unsynch'ed ROF for the Ho-103.

Shouldn't the Ki-84 nose guns also fire in the 400 rpm range, same as the reported rate of fire of the Ki-43 and other craft? They are the same guns, right: Ho-103?

Isn't this also the single heavy MG in the nose of the A6M5b we have in-game also? Thus that should also have a slower ROF? I did not quite time that one (it's linked to a 7mm, hard to add that one up), but it seems to fire pretty fast.




As another related issue, the C2's 12.7mm nose guns fire about 634 rpm in-game, but some cases the Breda SAFAT was rated/estimated down as low as 400-450rpm when synchronized. Strangely enough, that mimicks the similar Ho-103 performance found in several places, and the guns were very similar (I believe the Ho-103 fired a Breda shell).
Some other sources/studies show the synch'ed RPM as in the 550-575 range. It would appear our ROF is too high in-game (and yes I'm painfully aware of how slow the guns already fire on this plane!).

[Lusche]

Then I realized our Ki-84 has this same gun in the nose. At an in-game test that shows ~945rpm.

808 rpm for me: 26 seconds for 350 rounds.

[Wmaker]

None of the Browning .50cal family based guns and cannons took syncronizing well. Rate of fire dropped dramatically. As I understand it, in AH we have a universal fixed % RoF decrease for all weapons when they are syncronized.

[ink]

Is there a discrepency with Aces High's Ho-103 gun rate of fire?

I've been reading about the Terrible performance of the Ho-103 machine gun in Japanese service. Specifically, I was interested because of how the Ki-43 had one gun and then one much more reliable 7mm MG. Not only was the gun liable to jam or explode at first, but it was slow. Very slow. A combination of the Browning design and the Japanese synchronization gear, the gun reportedly only had a rate in the range of 400-450 rpm give or take. This was the very real reason why the Japanese pilots preferred the 7mm MGs so long into the war.

That made me wonder... The Ho-103 was common, right? You find it on our Ki-61 as well, but this is outside of the sync area, and fires unhindered from the wings. Doing an AH test gives roughly 882 rpm for those wing guns. Not bad.

I was thinking about the earlier versions of the Ki-61 that had the 4x 12.7mm guns or the MG151/20 in the wings and the 12.7m in the nose. I was thinking about how they would suffer the same problems with sync on this configuration.

Then I realized our Ki-84 has this same gun in the nose. At an in-game test that shows ~945rpm. Surely this is the unsynchronized rate, firing through the prop? That can't be right? Should it not be even slower than the unsynch'ed rate of the Ki-61? That seems to be the most high-end unsynch'ed ROF for the Ho-103.

Shouldn't the Ki-84 nose guns also fire in the 400 rpm range, same as the reported rate of fire of the Ki-43 and other craft? They are the same guns, right: Ho-103?

Isn't this also the single heavy MG in the nose of the A6M5b we have in-game also? Thus that should also have a slower ROF? I did not quite time that one (it's linked to a 7mm, hard to add that one up), but it seems to fire pretty fast.




As another related issue, the C2's 12.7mm nose guns fire about 634 rpm in-game, but some cases the Breda SAFAT was rated/estimated down as low as 400-450rpm when synchronized. Strangely enough, that mimicks the similar Ho-103 performance found in several places, and the guns were very similar (I believe the Ho-103 fired a Breda shell).
Some other sources/studies show the synch'ed RPM as in the 550-575 range. It would appear our ROF is too high in-game (and yes I'm painfully aware of how slow the guns already fire on this plane!).

you leave my KI alone

[Krusty]

808 rpm for me: 26 seconds for 350 rounds.

Well I did a test offline:
700 rds 12.7mm firing time: 22 s = ~ 954 rpm

I admit I could have fudged the test. Assuming it's the same ROF as you mention: that's still par with the unsynched guns on the Ki-61. It doesn't seem right. Shouldn't it be half that speed?

[Lusche]

Well I did a test offline:

So did I, twice, and stopped 26 seconds.

[Krusty]

So did I, twice, and stopped 26 seconds.

There ya have it, then. Like I described above, still seems rather high?


EDIT: I wasn't contesting your results, as much as explaining I wasn't pulling them out of thin air. I admitted I could have goofed on the timing test.

[Karnak]

IIRC, HTC does a generic 10% reduction in RoF for synchronized guns.


fyi, the Ho-103 is an Army gun.  The A6M5B used Navy guns.  I don't recall odd hand what the 13.2mm gun is called, but it is not a 12.7mm Ho-103.

[HighTone]

IIRC, HTC does a generic 10% reduction in RoF for synchronized guns.


fyi, the Ho-103 is an Army gun.  The A6M5B used Navy guns.  I don't recall odd hand what the 13.2mm gun is called, but it is not a 12.7mm Ho-103.

Off hand I think the Zeke 5's 13.2mm machine gun was the Type-3, built on a browning M2 design but upchameber for a 13.2 x 96mm cartridge.

[busa]

Hello.
This is busa01.

Since the text by Krusty is long for me, it cannot translate correctly.
Therefore, I introduce the official data of cycle rate.
I want it to become your reference data.

Ho103
The ammunition which Ho103 uses is the same as Breda SAFAT.
And it had HE bullet.(IJAAF developed.)
Bullet weight is 36.5g.
The main part of the machine gun is the copy of MG 53-2.
And since it was miniaturized, the ammunition of low power was used.
Because, it is for installing it in a nose.
In IJAAF, the nose gun was main gun.
The cycle rates of Ho103 are 800rpm.
I was not able to find the propeller synchronization rate.
I think that the cycle in Ki84 of AH is 350rds/800rpm 26.25sec.
Therefore, probably, the propeller synchronization is not simulated.
However, there are no data that the propeller synchronization has a problem in Japan.
Why is there such any reference in your country? 
Incidentally the problem of Ho103 was generated with HE bullet. 
It is neither jam nor cock off.
It was the problem of a fuse

Type89 7.7mm gun
Type89 gun is Vickers machine gun.
The standard of the ammunition which Type89 uses is .303 British.
The cycle rate is 900rpm.

Ho5
It is enlarged Ho103.
Ammunition is 20x94.
Bullet weight is 84g.
The cycle rate is 750rpm.

Type3 13.2mm gun (Naval gun)

It is the copy of MG 53-2.
Bullet weight is 52g.
The cycle rate is 800rpm.
The propeller synchronization rate is 700rpm.

Incidentally the character and performance of Ki61 in AH are not so real.
Ki61 is not a high-speed fighter.
The maximum speed was good, although maneuverability was bad, at high-speed.
The roll rate was lower than 109E4.
And at the speed of 200kts or more, the stick force was heavy.
Japanese Navy pilot said that "The handling at the high speed of Ki61 was the like a twin-engined airplane."
However, Pitch up was not generated even if speed increased.
Therefore, dive character was easier than Ki84.
However,dive acceleration was worse than 109E4 and P-40E.

Thank you reading for my poor english.

[Krusty]

The cycle rates of Ho103 are 800rpm.
I was not able to find the propeller synchronization rate.
I think that the cycle in Ki84 of AH is 350rds/800rpm 26.25sec.
Therefore, probably, the propeller synchronization is not simulated.

I agree, or HTC simply guessed at the synchronization.

There are a number of references to the 12.7mm slowing down significantly when synchronized.

One example:
http://www.warbirdforum.com/jaafmgs.htm

A couple of quotes:
"Pre-production models of the Hayabusa had two fixed machineguns in the nose, synchronized to fire through the propeller arc, one 7.7 mm and the other 12.7 mm (respectively equivalent to British caliber 0.303 and U.S. caliber 0.50). By the time they went into combat, however, those planes had been relaced by the up-gunned Ki-43-I, whose usual armament was two large-caliber machineguns. In their postwar memoirs, Japanese pilots reported that the results were disappointing: the large-caliber gun fired so slowly that on many of their fighters, the armorers replaced the port weapon with the older, 7.7 mm gun, thus restoring the armament mix of the earlier plane."

and later referring to the 12.7mm:
""The result was very successful," Mikesh writes, "but, like all Brownings, the gun did not synchronize well, losing much of its rate of fire." Its rated rate of fire, 900 rounds per minute, dropped to as low as 400 rpm in practice."

[busa]

Thank you for introducing a reference web page.

I think that I will investigate again pilot's book of reminiscences written in Japanese.

And I investigate the repair report of Ho103 in March, 1942 and afterwards.
It is the official data of IJAAF.
As for it, the repair situation of about 450 affairs is indicated.
In the report, the problem of a propeller synchronization did not have a special description.
Investigating the probability of the failure will require time.

Incidentally the address is the following.
http://www.jacar.go.jp/english/index.html
A reference number is the following.
C01000438500

Regrettably it is the Japanese original text.

Thank you.

[BaDkaRmA158Th]

Correct me if im wrong, but any guns firing through a prop is limited by the RPM of such said prop, therefor a engine running at higher rpm would allow for a higher rate of fixed "if abit the max for the gun itself" and a engine running at lower rpm would be limited by the fireing mechanism attached to the prop. "or whatever the technical term is."


Maby its just a game and htc doesn't feel like the rate of fire should be changed by the RPM of the prop.

[Krusty]

Doesn't quite work that way...

It's not just based on RPM. It's the cycles of when the prop passes in front of the gun and the natural cycles of the gun itself. If they are complimentary, things don't slow down much. If they just happen to be odd cycles you get much less windows of opportunity.

It also depends on the interrupter mechanism... Whereas on a more efficient one you might have a gun that fires 2 to 3 rounds between each prop blade, a poorer design might limit you to firing only 1 round then waiting for the next gap to fire 1 more round. I have heard of a design like this but I don't know if it was indeed the Japanese method or if it was some other (Italian perhaps?).

As for it, the repair situation of about 450 affairs is indicated.

Can you re-word that? Do you mean 450 rounds per minute? Or do you mean there are 450 records of repair you are reading through?

[Motherland]

It also depends on the interrupter mechanism... Whereas on a more efficient one you might have a gun that fires 2 to 3 rounds between each prop blade,

This sounds incredibly unrealistic