I decided to compile all synchronised aircraft guns and give them a RoF based on the delay of the German action to fire the gun, which is roughly 1/60 of a second.
By doing this I created what could possibly be the highest achiveable RoF of guns hoocked up to a synchroniser:
Gun
RoF
→
Synchronized Max
Synchronized Practical
Trigger delay 1/60
Synchronization delay 1/120
LMGs
ShKAS
1800
→
1200
1029
Browning
1200
→
900
800
MG 17
1200
→
900
800
Type 89
1100
→
843
755
Type 97
900
→
720
655
Breda-SAFAT
900
→
720
655
Vickers E
900
→
720
655
PV-1
750
→
621
572
HMGs
LKk/42
1100
→
843
755
Berezin UBS
1030
→
801
721
Ho-103
900
→
720
655
Type 3
800
→
655
600
AN/M2
750
→
621
572
Breda-SAFAT
700
→
586
542
Trigger delay 1/200
MG 131 EL
900
→
837
750
Cannons:
ShVAK
800
→
655
600
B-20
800
→
655
600
Ho-5
800
→
655
600
NS-23
600
→
514
480
Trigger delay 1/200
MG 151 EL
700
→
661
605
Because the gun can only fire when the gun is clear from striking a prop, the actually RoF would be lower and also dependant on the current prop RPM. So the real values would be on average around 5-10% lower. So I added another colum that shows the practical rate based on an average delay of 1/120s.
In case of the MG 131 and MG 151 I decided to change the trigger delay time from 1/60 to 1/200, due them firing electrically primed ammunition, which should result in higher synchronized RoF than mechanically fired guns.
The value is completely made up, so take it with a grain of salt. But I think it’s reasonable.
With this the RoF for the synchronized B-20 would be 600, which is the exact value stated by Christian Koll in his book “Soviet Cannon: A Comprehensive Study of Soviet Guns and Ammunition in Calibres 12.7mm to 57mm”
Ho-5 is an enlarged version of Ho-103, Ho-103 is a copy of the American Browning machinegun, by itself having the worse synchronized fire rate. The number of blades would affect the fire rate further, as they need the “safety margin”. Just because the blade is not in-front doesn’t mean it’s safe to fire, as they use so many mechanical components that are susceptible to lagging. Like the exacerbated friction from G-load, minor things can be deadly. The fire rates listed above are the “best case” fire rates I’d say. Like he mentioned, electrical primer and electrical trigger signals aided the fire-rate loss. Those 2 specific Japanese army guns are definitely affected by the variables.
Though it depends on the synchronization method, whether it tries to take every chance into account, or it simply ignores the number of blades and try to fire in a specific part per rotation. I have no idea what type of synchronization style they use.
Yeah but as long as we don’t know that’s the case and by how much, a general system would be the best approach.
Not necessarely. Props spin much faster than the RoF of the gun and what determines the number of firing delays is how synched up the prop RPM is to the RoF of the gun.
If we consider the maximum RoF of 900 RPM with a two bladed prop spinning at 900 RPM, we can use the full 900 RPM. Slight fluctians would induce a waiting period every now and then but in general the system can fire without interuption.
If we have a four bladed prop, it simply means that our safety zone is smaller and we more often have to wait, if there are fluctuations.
But of course in reality the prop doesn’t care about the RoF of the gun and when you have a three bladed prop spinning at 2000 RPM, you are ending up with a waiting period almost every shot.
Hence why the maximum synchronisation RoF can never be achived and I considered a waiting period for every shot.
So you’re probably right, that more blades means lower RoF but the you can see that with a fast spinning prop, the delay is actually rather small.
In my example we have a delay of 1/120s for every shot, which already slows the RoF from maximum quite significantly.
While it could be worse, by having a slower prop speed and poor synchronisation timings between gun RoF and prop RPM, I think it gives a good general result.
