Synchronised Aircraft guns

[oinkmoo]

Don’t feel excluded. Everyone here experiences that silent “nope”.
Noted, it’s the mods doing it. Not the Gaijin devs. So long as the draft passes, there is a chance.
My “rejected as draft” topics include

Contents

・Lock on a teammate to access more advanced communications like “behind you/ 6!” only heard by the targeted teammate. Combination of locking one enemy and one teammate to tell " XXX(enemy) behind you". New “lock a team” bind required, “lock an enemy or a teammate but not at the same time” key added.
・Self-sealing fuel tanks that are based on the caliber size. Leakage rate based on the hole size, the hole area based on the entry angle of the AP round. Fuel vapor that can be ignited mid-air with tracer rounds.
Self-sealing tier system, composite rubber rated for certain calibers.
・Reduced rip-speed and max load on damaged aircraft. The new limit indicated right next to the existing top left HUD.
・Variable BR based on a different gun installation like Ki-43-i (7.7mm). Ability to mount M2 (mid) to all aircraft equipped with M2(early), ability to mount M2 (late) to all aircraft equipped with M2 (mid). Practical update would be to add these to some major fighter aircraft, just to mitigate the workload.
Ho-103 (early) and Ho-103 (late) to all aircraft equipped with Ho-103, or else forced reduction in HEI contents in the belts. BR entirely based on the separate statistic profiles.
・Propellers that can be damaged from enemy guns based on a probability to hit one. Damaged propellers have reduced efficiency and keeps taking damage overtime, the propellers eventually fail. The area of the blade around the tips are not gonna get hit so often. But the mid section of the blades are gonna have the highest chance of getting hit.
・Randomized ammunition order in the belt. Asymmetric tracers.

Some other ideas I never bothered to suggest

Fixed presets for wing guns irl
Separate convergence for inward wing guns and outward wing guns. 100m~400m convergence in order, the configuration makes it easier to hit the opponent from the said distances even when the distance changes drastically over the course. Guns had different convergence to increase the probability of hitting targets. The effect got pronounced in x4 20mm guns.
(I will never use them even if they are in the game.)

[PercussionCap]

@oinkmoo

Separate convergence for inward wing guns and outward wing guns. 100m~400m convergence in order, the configuration makes it easier to hit the opponent from the said distances even when the distance changes drastically over the course. Guns had different convergence to increase the probability of hitting targets. The effect got pronounced in x4 20mm guns.

I’d use this, actually. Set one pair to converge about 100m in front of the other pair. Create a nicely spread out kill zone in the middle.

[oinkmoo]

I didn’t post the idea as a suggestion. So there is still a chance that they would accept the concept, at least open to the public.

[KillaKiwi]

It was not approved because:

Since gun synchronization affecting rate of fire is already present in game as you indicated, it would be a historical report matter on the community reporting site. You would need historical sources as well; applying German documents to American weapons would probably not be feasible.

Also:

If you want to know more about whether a bug report might succeed you should speak to one of our technical moderators.

I just can’t be bothered. Someone can write a mod or create a report but I have this feeling it will basically go down like this:

“Not accepted because you need a source for every synchronizer and every gun that every used that synchronizer, so instead we are keeping the impossible RoF as well as the completely made up synchronized values already in the game”

Basically that only Gaijin has the power to completely make up values or come up with a general approach.

[Ghostmaxi]

Out of curiosity, couldnt it already be that for the Mg 151 the fire rate of ~700 is the synconized, conciddering that the fire rate could be as high as 800 and 750 uncynconized. And the MG 131 also as high as 940 rpm (which was also seen in game on the Type 2?

[KillaKiwi]

No, it’s just that these US documents always give the most favorable RoF for the guns.

The RoF of guns generally fluctuate depending on the projectile mass and the resulting recoil forces.

The different projectile mass of the MG 151 and 151/20 shells can be substantial.

So while the manual basically gives an average of 700 RPM, the RoF for heavier shells could easily reach 800 RPM.

The MG 151 was generally loaded with more 57g explosive rounds than the 72g AP-T and the MG 151/20 manual has a weight for 20mm Mineshells of merely 86g compared to the shells which were 115g at that time.

The RoF of the MG 151/20 probably slightly increased over time, as the Mineshells got heavier and the other shells slightly as well.

Same story with the Ho-5, which either fired super light 84.5g shells or 123g AP shells, even heavier than the MG 151/20 shells.

So the RoF could be as low as 700 RPM but as high as 950 when firing AP-T.

Of course they only loaded a single AP for every two or three other rounds, so the practical RoF was 800 RPM or lower.

[Ghostmaxi]

But you still took the middle average then?

[KillaKiwi]

Well, of course.

The RoF has to be one value and the average makes the most sense.

[oinkmoo]

That makes so much sense.

[oinkmoo]

The in-game Ho-5 is 950 rpm.
Ho-103 is at 900 rpm.
There is no synchronization delay in the game.
Anyone touched FMod to mod war thunder audio would know that.
The fire rate of all ww2 guns are constant regardless of the mounting method in this game. The feature is not implemented as of yet.
You can see the obvious difference.
If you are using one of the logitech mouse or a keyboard, you can bind the loop macro with the specific interval per shot.
Doing this in an onlune match might send too much user imput to the server and snail might detect it weird. So it’s better to stick in mission editor sessions.

I’m in-line with using 825RPM for Ho-5 as the practical middle point. Then reducing the fire rate depending on the mounting method but no propeller rpm involvement. Just to familiarize. But it could be better to take the propeller rpm into the account.
It’s definitely better than the current behavior of the guns.

[oinkmoo]

The muzzle velocity must be from confusing 151/20 with 151/15.

[tester188-psn]

Here is data from Japanese sources on the actual RoF of synchronized machine guns used on the A6M. Among these, the Type 3 MG was based on the Browning design and used the 13.2×99 mm Hotchkiss cartridge. Although it is often said that Browning-type guns suffer a significant reduction in RoF when synchronized with a propeller, this does not seem to have been the case with the Type 3 MG.

Gun	RoF	Synchronized
7.7 mm Type 97 MG	950	650-750
13.2 mm Type 3 MG	800	600-700

When fitted with synchronization gear, the rate of fire becomes 600–700 rounds per minute.
同調装置とするときは発射速度は600～700となる

Spoiler

Source: “零式艦上戦闘機 歴史群像 太平洋戦史シリーズ, Zero Fighter, Rekishi Gunzō: Pacific War History Series Vol. 12.” Published by Gakken, 1996, ISBN-13: 978-4056012620, p. 91.

The Type 3 MG was equipped with the Type 3 synchronization gear.
https://dl.ndl.go.jp/en/pid/4009539/1/14
DATA ON THE TYPE 3 SYNCHRONIZER & SYNCHRONIZER CONTROLLER, YOKOSUKA Naval Air Group, April 1944. Captured on SAIPAN.

[KillaKiwi]

Similar what I got, using an general approach.

Maybe there still some hope.

[yo_sat]

@KillaKiwi

Except that the Type 97s RoF was recently increased to 1100 RPM, because according to the report the RoF could be lowered or increased from the default 950 RPM.

That report was prepared by me, but it is the Army’s Type 89, not the Navy’s Type 97. I would like to add this just to be sure.
https://community.gaijin.net/issues/p/warthunder/i/KZosxgmRAoN3

[KillaKiwi]

Oh right. I was thinking about the Army Type 89 😵‍💫

In WT the Type 97 has 900 RPM as far as I remember 🤔

[KillaKiwi]

https://community.gaijin.net/issues/p/warthunder/i/jFGsb9oyS2LL

Well, there you have it.

[Teh0]

Is it possible to calculate something from this?

Ki-44-II is the most broken prop fighter at its BR

As far as the Ki-84 is concerned, the synchronized gun firing timing appears to be twice per propeller revolution. [発射カム進角装置] 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 …

Does this help at all?

Spoiler

[tester188-psn]

In the case of the Ki-84, when the engine operates at 3,000 revolutions per minute, the propeller rotates at 1,500 RPM due to the reduction gear. Since the synchronization gear actuates the firing mechanism once every half revolution of the propeller, the gun can theoretically discharge once every two or 2.5 propeller revolutions—resulting in a cyclic rate of fire of 750 rounds per minute (1,500 ÷ 2) or 600 rounds per minute (1,500 ÷ 2.5), respectively.

A machine gun with an unsynchronized maximum rate of fire of 800 rounds per minute would have its effective synchronized rate reduced to approximately 655 rounds per minute when accounting for a trigger delay of 1/60 second. Taking propeller rotational speed into account, the effective synchronized rate of fire would vary accordingly, as illustrated in the graph below. Please advise if any discrepancies are noted.

[yo_sat]

I was wondering, if the propeller’s rotation speed is at its ideal speed, wouldn’t the gun’s firing rate be able to reach its maximum potential?

The time it takes for the synchronization cam to push up the trigger, and the time from when the trigger is pressed until the firing pin strikes the primer, these two times combined form what I believe is called “trigger delay.”
However, this delay occurs equally for the first shot, the second shot, and all subsequent shots. In other words, the trigger delay only delays the start of firing, but does not change the interval between shots.

However, this assumes that the gun’s firing rate is uniform. If there are variations in the firing rate for various reasons, synchronization with the propeller will not work properly.
As a result, the average synchronized firing rate will decrease.

[tester188-psn]

According to the German source, the firing rate is reduced at any propeller speed due to the trigger delay.

Consider the example of a Ki-84 with a machine gun on its nose with a firing rate of 800 RPM.

• Propeller rotation speed: 1,500 revolutions per minute (one revolution every 0.04 seconds)
• Impulse generation: Twice per revolution (one impulse every 0.02 seconds)
• Machine gun maximum rate of fire: 800 rounds per minute
• Machine gun lock time: 0.017 seconds

At time 0, the impulse generator activates the trigger, the sear is released, and the firing pin strikes the primer.
This lock time phase takes 0.017 seconds, during which the propeller rotates 0.425 revolutions, or 153 degrees.

After the bullet is fired, the bolt cycles: the spent casing is ejected, a new round is chambered, and the bolt returns to battery.
This mechanical cycling phase takes 0.075 seconds, bringing the total time for one firing cycle to 0.092 seconds.
During this time, the propeller completes 2.3 revolutions.

Then, 0.008 seconds later, the propeller reaches 2.5 revolutions, another impulse is generated, the trigger is pulled again, and the second round is fired 0.017 seconds later.

This entire sequence repeats continuously. For this reason, a machine gun with a firing rate of 800 rounds per minute can synchronize with 2.5 propeller revolutions and fire at a rate of 600 rounds per minute.

The trigger delay arises from the fact that synchronized aircraft guns operate in a semi-automatic firing mode, and this delay occurs independently of the propeller’s rotational speed. In semi-automatic firearms, the trigger must be pulled and the sear released for each shot, which means that a lock time is introduced with every round fired.
To eliminate this delay, the use of electric primers is highly effective. The Germans invested resources to adopt electric primers for this very reason.

According to US military research, the lock time for machine guns using a firing pin and standard primer can be reduced to as little as 0.008 seconds, but achieving a lock time shorter than this requires the adoption of electric primers.

In the case of the Ki-84, which has a propeller rotating at 1,500 RPM, achieving a synchronized firing rate of 750 rounds per minute would require:

• a full-auto firing rate of 950 RPM if the lock time is 0.017 seconds, or
• a full-auto firing rate of 830 RPM if the lock time is 0.008 seconds.

Some sources state that the Ho-103 and Ho-5 had firing rates exceeding 900 RPM, so it is plausible that they were capable of achieving a synchronized firing rate of 750 RPM.

Japanese 12.7-mm (.50 in.) Aircraft Machine Gun

The gun may be fired full-automatic from the open bolt as well as single-shot or semi-automatic from the closed bolt.

Rate of fire: 983 r.p.m. cyclic

Catalog of enemy ordnance material.
https://dl.ndl.go.jp/en/pid/4009929/1/78

Spoiler

“US Armament in the Air War.” USSBS. August 1945. p. 10
https://pdfcoffee.com/us-armament-in-the-air-war-pdf-free.html

During World War II, the Mauser 20mm cannon mounted on German fighters adopted electric primers, which comprehensively solved the issues related to the firing pin. Thirty years later, electric primers were again adopted for the M61 Vulcan cannon mounted on the F-104 Starfighter.

The time required for the mechanical movement from trigger pull to firing pin impact—though dependent on the design of the firing mechanism—is generally considered to be around 0.008 seconds. The United States strongly advocated that using electric primers, which reduce this time to virtually zero, is essential for increasing the rate of fire. This is cited as the reason for adopting electric primers.

Spoiler

“兵器と技術 Weapons and Technology (285),” Japan Defense Equipment Industries Association, February 1971, p. 57.