Best tank-busting armament

Agreed, if provided with decent engines the Hs-129 could of been (and would of been) the best anti-tank plane of the war. Although I think they would still have been shot down in droves when the Germans lost air superiority but then the FW-190F could still operate so not all would be lost.

Agreed. The aircraft would have been the best at its intended purpose throughout the war however once the Luftwaffe lost airsupperiority she would have been a sitting duck.

In some ways she was similar to the Ju-87. She was very good at her job but not very maneuverable and sluggish, shot down in droves without propper protection.

I still think she would have been a ***** to take down though. She was a tank with wings!

Yep! She would of been even harder than the Il-2 to knock down, and with the Russian fighters light armament they would of found it very hard to shoot it out of the sky.

The best gun was probably the Soviet NS-37: it was smaller, lighter, faster-firing, more powerful and had a much bigger ammunition supply than the German BK 3,7 (which was just a modified Flak gun rather than being specially designed for the job). However, the BK 3,7 had better ammunition - the tungsten-cored Hartkenmunition - which gave it more penetration in most (but not all) circumstances.

The 'Tsetse' Mosquito was originally designed for tank-busting, but the RAF went off the idea so they were handed over to Coastal Command instead. A pity really, the gun was very accurate and powerful.

If you want to know about the performance of the different anti-tank guns, you'll find it here: TANKBUSTERS: AIRBORNE ANTI-TANK GUNS IN WW2

Rockets were too inaccurate to be really effective as anti-tank weapons. The RAF calculated that in action only about one in two hundred would score a hit. Bombs were even less accurate.

The most effective airborne anti-tank weapons were probably the Soviet and German cluster bombs - a shower of small bombs dropped from a container. These covered a wide area with a strong probability of hitting a tank, and they could blow a hole through the top armour.

Tony Williams: Military gun and ammunition website and discussion forum

The Luftwaffe had a better rocket launch to hit ratio with the Fw 190F than the RAF did, but it was an inaccurate way to destroy a tank...

I still feel that the heavy cannon was the better way to destroy enemy armour on the move... Tanks were usually dispersed, not crowded together, making cluster bombs partially useless....

And besides, bombing was a much less accurate method, cluster munitions or not...

From "Flying Guns – World War 2: Development of Aircraft Guns, Ammunition and Installations 1933-45":

"Also introduced at Kursk was the PTAB (Protivotankovaya Aviatsionnaya Bomba = anti-tank aircraft bomb). Versions weighing 1.5 and 2.5 kg were used, and these relied on a hollow-charge warhead to penetrate up to 60-70 mm of armour. Some 192 PTABs were housed in a KMB canister, of which four could be fitted into the internal bomb bays. These were usually released en masse from 70–100 m altitude, covering an area of 15 x 70 m (i.e. an average of one for every 1.3 m2) and were highly effective, being rated by the Soviets as the best method for dealing with tanks and two to three times more effective than ordinary bombs."

Tony Williams: Military gun and ammunition website and discussion forum

...sounds plausible to use bomblets with hollow charges.

Here some penetration figures for
(from close distance, >500 yrds and with a speed advantage of ~320 fps against a plate of Q:1.0 and el:20%, standart high quality US armour plate)
40 mm (Hurricane IID): 59 mm at best impact obliquity, lowering down to
~17 mm @ 60 deg. impact obliquity
NS 37: 95 mm @ 0 deg. impact obliquity, lowering to 23 mm @ 60 deg. impact obliquity, sufficiant to defeat most german tanks, except for Tiger and King Tiger.

Thanks for that. Where did you get the NS-37 data from? The only sources I've found say 48mm/500m, although that's always seemed a bit low to me.

Tony Williams: Military gun and ammunition website and discussion forum

M79APCLC calculator for penetration of homogenious armour. Used the shell body of the standart US M79 AP round, which is in the middle of blunt shaped and very pointed. If You know the metal properties (source the net) and some ballistic datas (most important beeing weight, size, impact velocity and impact obliquity), the program does the penetration physics for You. Depending on nose shape the program is correct in more than 92% of the cases.

It's curious that the Soviet penetration data should be so much worse than the results of the calculations. Furthermore, I have a German ammo test chart (they tested everything they could get hold of) which lists the penetration of the NS-37 AP at 45mm. Maybe it was something to do with the quality of the Soviet AP projectiles (which were a bit iffy in tank guns IIRC).

Tony Williams: Military gun and ammunition website and discussion forum

It all depends on the circumastances of impact. And of course on the projectile properties. AP-solid and/or APC shots made of low grade steel were common to soviet A/C guns. In so far they were inferior to the US rounds, but not by much.
The 45mm figure fits well to a plate net impact obliquity of 30 deg. Sadly not all such circumstances (area of hit into the plate, true impact obliquity, plate properties[elongation, brinellhardness, thickness, SS], target angle, true impact velocity) are noticed in test results (sometimes plates have been repeatedly striked, suprise, they achieve penetration!), this makes it impossible to compare the results with other ones.
I did a lot of digging into this matter and so far, I believe M79APCLC is the best penetration system out there. Thousends of plate properties have been analyzed to rule out the physical background of penetration processes for homogenious armour.

The strange thing with AP-shots is that they usually are solid. So the momentum of impact and the impact obliquity defines whether or not the projectile will defeat a certain plate or not. The differences in nose shape from very pointed via blunt shaped to flat nose are significant, but not by that much (blunt shaped projectiles tend to have a better penetration ability at high obliquities for tradeoffs in low obliquities). Other than by extreme differences in plate properties and / or projectile properties, I cannot explain the problem. Even a flat nose 37mm projectile of 1.67lbs would defeat a 45mm US standart plate at 0 deg. with any striking velocity bigger than 2078 fps (627 m/s terminal impact velocity equals a flight distance of ~1500yrds, energy/unit of hole volume:37498 foot pounds/cubic inch). Assuming a plane makes 300 Km/h, the initial velocity of the projectile is 973 m/s (3241 fps), which would be sufficiant to penetrate 90 mm of US armour grade material at 0 deg. impact obliquity for a flat nosed-blunt shaped projectile (energy/unit of hole volume: 45585 foot pounds/cubic inch)! The NS-37 actually has no flat nosed projectiles, so penetration at 0 deg. should be higher. Hence, even if we assume the test plate is of extraordinary strength (which may be the case for extra hard 45mm plates), the projectile will initially defeat 81.8 mm