Differences between the "Type 99" and MG-FF?

[Urchin]

What are the differences between the Type 99 cannon mounted on the A6M-5 (and the N1K2) and the Oerlikon MG-FF mounted on the 109E4?  I thought the Type 99 was a direct copy (manufactured under license) of the Oerlikon design, but this doesn't seem to be the case in Aces High.  

The A6M5's cannons have a straighter trajectory, higher velocity, and they hit harder than the 109E4's cannons do.  Why?

[-=Silo=-]

The Type 99-1 was the rough equivalnt to the MG-FF

However, the 99-1 was replaced with the 99-2. The type 99 Model 2 fire the rounds at a greater velocity, but actually had a slower rate of fire than the Type 99 Model 1.

Here are some common usages in IJN fighters.

A6M2         - Type 99 Model 1
A6M3 32    - Type 99 Model 1
A6M3 22a  - Type 99 Model 2
A6M5         - Type 99 Model 2
J2M3          - Type 99 Model 1 and Type 99 Model 2
N1K2-J       - Type 99 Model 2

[HFMudd]

Type 99-2: 129 g, 490 rpm, 625 m/s
MG-FF: 134 g, 520 rpm, 600 m/s

..and for comparison...

Hispano Mk.II: 130 g, 600 rpm, 880 m/s (But... it weighs almost twice what the MG-FF does)

[Urchin]

Ok, I'd like this explained/clarified for me.  

The MG-FF fires a heavier bullet (it is 5 grams heavier, right?), at a slightly lower speed (25 m/s less, right?).  So, as far as hitting power goes, how do you calculate it?  Is it weight times muzzle velocity?  

If it is weight times muzzle velocity, the MG-FF comes out at 80,400 somethings lol.

The Type 99 Mk2 comes out at 80,625.

The Hispano comes out at 114,400.  

Well, it appears to be obvious that the Hispano (I keep having to fight typing Hizooka) should hit harder than the MG-FF and the Type 99 Mk2, and it does in AH.  

However, the results between the Type 99 Mk2 and the MG-FF are really, really close.  As it is now, a MG-FF round probably falls about halfway between a .50 caliber round and a MG151 round.  
The Type 99 seems to hit about as hard as the Mg151 does.

Add to that a trajectory that seems somewhat worse than the 30mm Mk108 and you have a weapon that is essentially useless, in my opinion.

Just from laymens experience in the game, I'll try to list the damage (against other planes) for the guns I've got experience with.  

37mm (Yak gun): 1-2 hits will kill.
30mm Mk108:  1-2 hits will kill.
23mm (Il-2 gun): 2-4 hits will kill (2 on the same spot will usually kill)*
20mm Hispano: 2-4 hits will kill (see above)*
Mg151/20: 3-6 hits will kill (usually 3-4 in the same spot will kill)
Type 99: 3-6 hits will kill (see above)
MG-FF: 8-12 hits will kill (I've hit someone 6-7 times in the same spot for no damage several times, at ranges from 300 to 100 yards)
.50 caliber M2: 15-20 hits will kill (sometimes more, up to 30 or so).
Mg 131: 15-25 hits will kill (less if you are close, more if you are far away
C202 12.7mm: 20-25 hits, usually.  
7.92 LW guns:  See above
.303s : See above

Effective range:  Tail shot/ Head on shot - Range you can fire and expect to land a burst.

.50 caliber: 800 yards/ 1200 yards (thats conservative)
20mm Hispano: 600/ 1000 (or so) yards.
Mg131: 600/1000 (or so) yards.
Mg151/20: 400/800 (or so) yards.
Type99: 400/800 (or so) (Honestly seem a lot like 151/20s to me)
C202: see above
7.92 LW:  400/800 (or so)
.303 -  honestly not much experience, I'd guess 400/800ish.
MG-FF: 150/450 or so.

And finally, trajectories.  

.50 caliber: nice and flat almost out to 1000 yards.
20mm Hispano: nice and flat to about 800 yards or so
Mg131: Nice and flat for about 600-700 yards.
Mg151/20: Nice and flat for about 400 yards.
Type99: See above.
.303/7.92: Flat for about 400-500 yards.
Mk108: flat for about 200 yards.
MG-FF: flat for maybe 150 yards.. maybe.

Of course, this is all just what I've experienced in Aces High.  I'm not a ballistics expert, never fired any of these guns in real life.  I'm perfectly happy with the MG151/20, I've reconciled myself to the fact that it is no Hispano.  What I don't understand is why the MG-FF is so horrible?  Why does it have so much drop in such a short period of time?  Furthermore, if you are trying to take a tracking shot on someone in a flat turn (assuming you are behind them) you have to lead the other plane so much (even at 100 yards) that you can't even SEE the other plane- it is somewhere around your instrument panel.  You don't even have to lead that much with the Type 99s or Mg151s (what the particulars on the MG151/20 anyway?).

[Karnak]

The MG/FF has a metric calibre of 20 x 80RB.  The muzzle velocity is 600 meters per second.

The Type 99 I has a metric calibre of 20 x 72RB. The muzzle velocity is 550-600 meters per second.

The Type 99 II has a metric calibre of 20 x 101RB.  The muzzle velocity is 750 meters per second.

Essentially the Type 99 I is the same gun as the MG/FF on the Bf109E-4.  They have nearly identical ballistics and are both limited to 60 rounds due to their drum feed mechanism.  Both the MG/FF and Type 99 I are heavily based on the Oerlikon FF.

The Type 99 II was based on the Oerlikon FFL, which also allows the A6M5 and N1K2 to have much greater ammo supplies due to its belt feed mechanism.

[Urchin]

I don't understand, Karnak.  

Whats the difference between a 20x80RB (whats an RB?) and 20x101RB?  

Is the 20X101 longer?  

Thanks for the info on the muzzle velocity though, that would explain why you dont have to lead as much with the Zeke as you do with the Emil.  

Whats the stats on the MG151/20?

[brady]

Urchin you are forgeting I think this, The Japanese fired an almost all HEI ammo load they did not mix their chaines like the Germans did, I have been told the Type 99 rounds hit like 99% as hard as Hispano rounds due to the fact that the added chemical engery in these rounds is factored into their effectiveness in AH. In fact the AP round in the chain was the tracer so like only one in 4 or 5 was the AP rond all the rest were HEI.

[Karnak]

Urchin,

Quite honestly, I'm taking numbers straight out of Tony William's book.  I don't know what all of the stuff means, "RB" for example.  I was posting the data in the hope/assumption that it would be understood by people who know their ammo/guns.  I do aircraft, not guns.

Yes, the Type 99 II is longer than the Type 99 I or MG/FF.  The length in this case is, I am pretty certain, including the cartridge.  The weight of the shell given in Tony's book is the same for the Type 99 I and Type 99 II.  I belive that the larger cartridge gives the Type 99 II its superior muzzle velocity.

Guns/cannon of interest as described by Mr. Williams:

Format: Gun(s) | Metric Calibre | Projectile Type/Weight gm | Muzzle Velocity m/sec | Muzzle Energy joules |

Breda-Safat 12.7mm, Ho-103: | 12.7 x 81SR | 36.7 | 760 | 10,600 |
.50" Browning M2 | 12.7 x 99 | AP/46 | 880 | 17,800 |
MG131 | 13 x 64B | HET/34 | 750 | 9,600 |
Type 99 I | 20 x 72RB | HE/128 | 550-650 | 19,000-23,000 |
MG/FF | 20 x 80RB | HE/134 | 600 | 24,100 |
MG151/20 | 20 x 82 | HE/115 | 710 | 29,000 |
Ho-5 | 20 x 94 | HEI/79 | 730 | 21,000 |
ShVAK, B-20 | 20 x 99R | HE/97 | 860 | 35,900 |
Type 99 II | 20 x 101RB | HE/128 | 750 | 36,000 |
Hispano Mk II | 10 x 110 | HE/130 | 880 | 50,300 |
VYa | 23 x 152B | API/200 | 880 | 77,400 |
MK 108 | 30 x 90RB | HE/330 | 505 | 42,100 |
MK 103 | 30 x 184B | HE/447 | 800 | 143,000 |
NS-37 | 37 x 195 | AP/735 | 900 | 298,000 |
Vickers Class S, aircraft | 40 x 158R | AP/1,130 | 615 | 214,000 |
BK 5 | 50 x 419R | AP/2,060 | 835 | 718,000 |
Molins 6pdr | 57 x 441R | AP/3,170 | 790 | 989,000 |

[Tony Williams]

There is a history and "family tree" of the Oerlikons, Type 99s, MG-FFs, MK 108 etc on my website (see "Of Oerlikons and Other Things")

The MG-FF and the Type 99-1 were effectively the same in their performance (127-134g at around 600 m/s). However, the MG-FFM, introduced in May 1940 in the Bf 109E-4, was modified to accept the new "Minengeschoss" mine shells. These were thin-walled, high capacity shells (they contained around 20g HE compared with a maximum of 10-11g for other 20mm) and only weighed 92g, which enabled the muzzle velocity to be upped to around 700 m/s. Because they were light and had a blunt shape, they lost velocity very quickly and had a relatively short range.

The Type 99-2 had a longer cartridge case to house more propellant, which put the muzzle velocity up to 750 m/s, using the same 127-134g shells. These contained about the same HE as the Hispano (ie 10-11g max).

Relative hitting power is a difficult one to summarise, because it all depended on the circumstances. The M-Geschoss was highly effective when it detonated in a confined space because it relied on blast effect to generate pressure. The other shells formed larger fragments when they detonated, sending these flying through the structure. This might be more or less effective depending on where it hit.

Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine
guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages/

[Tilt]

Originally posted by Urchin
Ok, I'd like this explained/clarified for me.  

So, as far as hitting power goes, how do you calculate it?  Is it weight times muzzle velocity?  

For kinetic energy its force = mass x acceleration

Acceleration is velocity squared/2

so its weight times the square of velocity/2.

This of course takes no account of drag or explosive energy (of a cannon round)

Hence a % difference in velocity has a far greater effect on kinetic energy (range and impact) than the the same % difference in weight. (a 4% difference in velocity is a 8% difference in Energy where as a 5% difference in velocity is a 12.5% difference in Energy.......... a 5% differnce in weight is a 5% diference in Energy)

This affects range and residue impact energy.

As others have said trying to factor this into a lethality constant is very hard due to the different circumstances a cannon round may find its self in when it explodes. And off course the potential chemical energy in the charge and how it is transfered to actual kinetic energy........ thin wall shells rely on pure explosive force acting on the surrounds........... thicker wall shells operate more like a grenade to convert the potential chemical energy into the kinetic of the  shell fragments.

To be truly effective a thin wall shell will be required to penetrate into a confined space (eg wing section) whilst a thick wall shell can also do damage in the larger cavities and even some without penetrating the AC structure.  As you have to sacrifice chemical energy to achieve a thicker wall you are therefore seeking a compramise.

This would be decided by your typical choice of target.

It would be an interesting addition to enable players to choose typical shell types for their AC guns just as they can for their tank rounds now.


HTC will be forced to tread a middle line on this but we can imagine the complexity with which they are faced in terms of subsequent range and lethality modelling.


Tilt

[Tilt]

Originally posted by Tony Williams
Because they were light and had a blunt shape, they lost velocity very quickly and had a relatively short range.

Would you agree that their "lightness" has little to do with the loss of velocity..............?

A large but light feather with a kinetic energy of 10,000 joules has the same kinetic energy (force) as a smaller but heavier brick with a Kinetic energy of 10,000 joules.

Indeed given the brick is heavier but slower the affects due to gravity on trajectory are greater.

Drag however directly bleeds kinetic energy and so our feather lighter but having a greater surface area suffers a  reduction in velocity.

Given that Muzzle velocity compensated for weight to produce the same kinetic energy then indeed the smaller/lighter round would enjoy greater range.(if the drag coefficient for both were the same)

Tilt

[Tony Williams]

Originally posted by Tilt


Given that Muzzle velocity compensated for weight to produce the same kinetic energy then indeed the smaller/lighter round would enjoy greater range.(if the drag coefficient for both were the same)

Tilt

But the drag coefficient is directly affected by the weight for a given calibre. There are two elements in calculating the drag coefficient; one is the aerodynamic shape of the projectile, the other is the sectional density, which is a ratio between calibre and weight. The M-Geschoss was the same shape as a conventional shell but much lighter, so both its SD and ballistic coefficient were considerably worse. That is why it lost velocity more quickly. In fact, it lost 60% of its velocity at 600m, compared with around 40% for the conventional shell.

Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine
guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages/

[Tilt]

Originally posted by Tony Williams


, the other is the sectional density, which is a ratio between calibre and weight.

I cant see the physics behind that...... is it an imperical factor?

If two projectiles had the same muzzle velocity but one weighed less........... then its(the lighter) total kinetic  energy is lower and it will loose velocity quicker.... even if drag is the same.

in other words for the same muzzle velocity the  lighter projectile will always loose velocity faster. (it has a lower kinetic energy)

but for the same energy at the muzzle (mass x accel) I would assume that given equal drag (aerodynamic) they would both loose velocity equally except the heavier would be more subject to gravity.

This is begining to look a bit pedantic I just wanted folk to be wary of thinking that lighter always meant shorter range. When really its kinetic energy and drag(aerodynamic) that effect range.

Tilt

[HoHun]

Hi everyone,

I'd like to point out that the kinetic energy of a projectile isn't necessarily proportional to its hitting power. The German mine shells had a much greater explosive content than normal explosive rounds, and they were designed to wreck an aircraft's structure.

While armour piercing rounds had a much better penetration than mine shells, they had to rely on hitting critical components, which were few and small. As mine shells attacked the aircraft structure, they were effective almost regardless of where they struck the target.

Since the main destructive component of the mine shells was the explosive content, the MG FF/M mine shells were just as effective as the MG151/20 mine shells, though of course the latter's higher muzzle velocity made hitting easier.

Regards,

Henning (HoHun)

[Tony Williams]

Originally posted by Tilt


This is begining to look a bit pedantic I just wanted folk to be wary of thinking that lighter always meant shorter range. When really its kinetic energy and drag(aerodynamic) that effect range.

Tilt

To be precise it is the combination of ballistic coefficient and muzzle velocity which determine the range.

Ballistic coefficient is important because it determines the rate at which the projectile slows down (the "aerodynamic drag", if you like).

In conjunction with the muzzle velocity, the ballistic coefficient determines the projectile time of flight, which is the key figure for two reasons; the shorter the flight time, the greater the hit probability, and also the less time gravity has to work on the projectile, so the less it will drop below the line of sight.

For those reasons, the flight time determines the effective range, although if you are relying on kinetic energy the effectiveness of the bullet strike will obviously reduce with range, whereas as Henning pointed out, cannon shells relying on HE to do the damage stay more or less equally effective at all practical ranges.

Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages/