20mm: Yak-9u vs. BF-109g2

[Slade]

Hello,

Which 20mm nose mounted cannon is better between these two planes: Yak-9u vs. BF-109g2 and why?

Just comparing the 20mm between the two please.


Thanks,

Slade 

[glzsqd]

tough call, I'd give the edge to the German 20mm though. More bullets decent Rate of fire and good punch, I beleive the MG151 also has superior ballistic properties.

[Lusche]

With its higher muzzle velocity the ShVak of the Yak-U should have the better ballistics (flatter trajectory). It does a tad less damage than the 109G's Mg 151/20. IIRC RoF is about the same as well.

The only really major  practical  difference is the ammo supply, 200 (109) vs 120 rounds (Yak)

[PR3D4TOR]

They are about the same in ballistics and rate of fire, but the MG 151/20 has more bang per round (and more ammo in this match-up).

[glzsqd]

With its higher muzzle velocity the ShVak of the Yak-U should have the better ballistics (flatter trajectory). It does a tad less damage than the 109G's Mg 151/20. IIRC RoF is about the same as well.

I stand corrected

[PR3D4TOR]

The ShVAK does not have a higher muzzle velocity with typical belting. 750(AP)-790(HE) meters per second for the ShVAK and 720(AP)-800(HEM) m/s for the MG 151/20. Depending on ammunition belting they would average out to about the same.

[bustr]

ShVAK 20mm, flat to 200m(3in low) while shooting 24 inchs low at 400m. From a ww2 Russian table the ShVAK 20mm round was 800m\sec, bullet 96gm. Depending on the source the ShVAK AP and HE were the same weight and shape to make their ballistic performance the same unlike german rounds. MG151/20 is slower so has a perceptible ballistic curve to account for. The 20mm M-Geschoss InitV is 785m\sec, bullet 92gm, while the rest of the HE types for the MG151/20 were 705m\sec, 116gm bullet.

M-Geschoss 15in low at 200m, 6ft low at 400m.
ShVAK 3in low at 200m, 2ft low at 400m. <---- shoots like an AN\M2 .50 with more bang.

Russian air combat doctrine looked at effective shooting ranges between fighters as 200m(218yds). Units in the field moved that to 400m(437yd) but, that was more for bombers. German air combat doctrine looked at 225-250m as the effective range against fighters. And 400-500m for bombers. That is why the MG151 20mm is set for an IP at 500m while the pilot learns where 225-250m is on his reticle. That is the first sweet spot confluence of cannon and hood MG rounds for getting rounds on a maneuvering fighter.

Round ballistics for the MG151/20 in the game. I don't know Hitech's source for ballistics. The two most common are either Munitionsvorschrift Teil 10 or Bordwaffenmunition 1936-1945. Russian ballistics for the ShVAK are often in modern times taken from post WW2 Czech produced rounds used in ground positions and GV which have lower InitV than the "fixed mounted" for ww2 VVS fighters which was 800m\sec.

[PR3D4TOR]

I was going by Tony Williams data. Gun performance in AH seems to mirror that data pretty closely. I have no idea what source(s) HiTech uses.

[bustr]

And Tony is going by a POST war manual written for Russian ammo that is using the Czech ammo figures.

Here, WW2 Russian page from a manual. Hunting down manuals from WW2 and translating them is a bite me big time. Just like finding what the reticle for the PAK1 in the I16 really looked like and how gigantic it was. 140Mil main ring.

[PR3D4TOR]

Very nice!

However we still don't know the ShVAK's in-game performance, which I believe is what Slade is asking for. To me the ballistics of both guns seem very similar in AH.

[bustr]

Offline in the drone circle on zoom you can see the difference.

[PR3D4TOR]

Using the .target function and comparing shell drop at various ranges would be a more accurate approach.

[icepac]

Yep.


I use it to set convergence of my guns by the shell drop only and don't consider the horizontal at all.

[bustr]

Using the .target function and comparing shell drop at various ranges would be a more accurate approach.

Until you pull lead increasing your G. Especially as you get towards 20 degree off. That is why I told you to try the drone circle on zoom and watch your tracers. Obviously you didn't. Static shooting only shows you the static 1G effect which the rounds ballistic data is given for. You have to really dig for the G loaded data from ww2.

As you pull lead you increase the G load which effects the bullet drop. The only way to see this in the game: Up into the drone circle with tracers on. Hit zoom and zoom in, then shoot at the turning drones as you are forced to hold lead in your own turn. That old illusion thingy of the tighter you turn horizontally in a furball on the deck, the tracers all curve behind your target.

At 1G the US 50cal and 20mm drop 39 and 48 inches at 400yds. Increase that to 2G, and the drop averages to about 6ft at 400yds.

Ever wondered why when you dive on someone and you are going 400-450, and he seems completely oblivious and sits there, that you seem to have to use a lot of elevation just to land hits at 400? As you pull your vertical lead, nose coming up at the bottom of your dive. How much G are you creating?

2, 3, or 4G maybe?
 
1G - 2ft drop 400yds
2G - 6ft drop
3G - 13ft drop
4G - 20ft drop

You didn't try the drone circle offline did you.....

[PR3D4TOR]

I don't have the game installed, so no. I'm waiting for the update to try it out again. However, if the two guns have the similar static bullet drop at 100 yards they also have similar muzzle velocities. The MG 151/20 mine shells have poor aerodynamics so at longer ranges they will drop more.

What you're describing has nothing to do with G, but relative velocity vectors, and they vary from aircraft to aircraft depending on wing loading and control authority (aircraft "mushing"). When you're pulling G the velocity vector drastically changes in relation to where your guns are pointing, thus imparting a velocity to the shell that is out of alignment with the shells own velocity vector as it exits the muzzle. It is best observed by using a gun turret on a fast bomber like the B-26. Firing straight ahead gives you the normal tracer trajectories you'd expect, but the more you point the guns away from the aircraft's velocity vector the more the tracers will deviate due to the aircraft's own velocity being imparted to the shell at an angle. The sideways drag will make the shell weathervane into the aircraft's velocity vector thus forcing the shell to fly a curved path into the aircraft's velocity vector (into the wind as it were). Finally gyroscopic drift due to the torque of weathervaning will make the shell curve up or down depending on which side of the aircraft the turret was pointing and the direction of the gun's rifling.