Why Were Tanks Such Difficult Targets For Aircraft During WWII?
AFVs, particularly medium or heavy tanks, were probably the most difficult targets for aircraft to attack in WWII. Given the more realistic historical assessments detailed (above) for Normandy and Kursk, objective analysis shows why aircraft attempting to attack armour in WWII faced several major hurdles.
During WWII, aircraft with unguided weapons were relatively inaccurate. To a lesser extent this is the case even today and there is no comparison with modern combat aircraft with guided weapons. Against soft targets this was not as critical because bombs and rockets deployed by WWII aircraft were area weapons. Even so, small soft targets such as entrenched AT guns were difficult for WWII aircraft to destroy. Small pinpoint targets, like a moving tank, were very hard to hit because tanks required a direct hit with an AT weapon or a near miss with a very large air launched weapon to destroy it. Even much larger moving targets such as ships were difficult to hit by modern standards. This inaccuracy stems from the nature of aircraft and the state of guided weapon technology at that time. In practical terms this meant that for an average fighter-bomber conducting a strafing attack, the tank remained in the gun sight for approximately a 10th of a second! Even if the pilot was to point his aircraft straight at the tank, a difficult and dangerous manoeuvre against a heavily protected target like a tank spearhead, he would have had at most a few seconds to aim his cannon, MGs, rockets or bombs.
Land based vehicles could carry enough ammunition to sustain approximately an hour of combat, but aircraft could not. Aircraft carried very limited ammunition for their permanently mounted weapons such as cannon, and obviously carried relatively limited numbers of individual air launched weapons i.e. bombs and rockets. This meant they could only attack the target for a very limited time compared to land based weapon systems. Even late in WWII, aircraft only carried sufficient ammunition for 1-4 passes on the target.
Most aircraft mounted automatic weapons were not designed for sustained fire. Apart from ammunition considerations, these weapons quickly overheated and would likely jam if fired for more than a few seconds at a time. Most often they were fired in shorter bursts suited to air to air combat.
Aircraft mounted weapons spent much less time in service (i.e. actually exerting their lethality), then ground based weapons due to overall aircraft malfunctions. This is in addition to the weapon’s Reliability Factor (RL), which only considers the inherent reliability of the weapon itself.
Aircraft were not suited to carry large calibre and high muzzle velocity AT weapons. This was due to the weight of the weapon with more than a few rounds of ammunition and the very severe recoil stresses placed on the airframe. The largest AT weapons placed on WWII aircraft were the 75mm Pak40L guns on the Henschel Hs 129B-3 and the Junkers Ju 88P-1. Neither aircraft was particularly successful with the ‘monster gun’ really proving too much for the airframes. The Hs 129B-1/2 with 30-37mm AT guns was more successful, while Ju 88P remained one of the few unsuccessful developments of the basic Ju 88 design. It is worth mentioning the relatively successful Ju87G-1, armed with two 37mm BK (Flak 18) AT guns. This modification provided the obsolescent Ju 87 with a new lease of life late in WWII. It is interesting to not the Hs 129B-3 carried only four 75mm rounds while the Ju87G-1 carried only 12 37mm rounds. Good examples of the very limited amount of ammunition carried for aircraft mounted weapon, discussed above.
During WWII, the large majority of aircraft attacking tanks with aircraft mounted weapons used 20mm cannon or simply HMGs. These include aircraft such as the Supermarine Spitfire, Hawker Typhoon, Hawker Tempest, De Havilland Mosquito, most Ilyushin Il-2s and Il-10s (some had 37mm cannon), Yakovlev Yak-7/9, Petlyakov Pe-2/3bis, Lockheed P38 Lightning, North American P51 Mustang, and the Republic P47 Thunderbolt. The average 20mm cannon with standard ammunition had great difficulty penetrating the 12-15mm top armour on the Pz IV H, and almost no chance against the 16mm top armour on the Panther and the 25mm top armour on the Tiger I, even if they managed to hit them! The reader should also bear in mind that on average the strike angle of cannon shells on the top of AFVs was usually in the region of 30 to 60 degrees, because aircraft could not attack vertically downwards (the Ju 87 Stuka came closest to this ideal attack angle, which also dramatically increases the accuracy of any air launched ordnance). In general 20mm cannon only inflicted superficial damage on even light tanks, with the most severe damage being penetrations through the top engine grill covers and damage to the engines. Unless the battlefield situation dictated that these tanks became operational total losses (eg, abandoned due to retreat), then they were usually quickly repaired and returned to service.
The lack of a suitable anti-tank armament meant all these aircraft had to rely on much less accurate air launched weapons (i.e. rockets and bombs) to kill late war German tanks. Late war rockets and heavy bombs were capable of destroying a medium tank, but were considerably less accurate than the already inaccurate fire from cannon and MGs. Against a Panther or Tiger tank, nothing short of a direct hit was going to even have a chance of destroying them.
AFVs and tanks were usually found in forward combat units and ‘spearhead’ attack formations. These units often had light and medium flak units protecting them which consisted of 20-37mm mobile flak guns. Even in 1941 during Operation Barbarossa, German panzer divisions had integral light flak units with the panzer regiments. This made tank targets extremely dangerous to attack compared to most other ground targets. In addition, aircraft attacking tanks were required to attack at low level, well in reach of light flak guns. The flak also meant fighter-bombers were less able to fly using a nice straight attack approach, and were often thrown about by exploding flak shells, further reducing their accuracy. Indeed it seems that air attacks on tanks protected by flak were more dangerous to the aircraft than the tanks. The 1 726 fighter-bombers lost from the 2nd Tactical Air Force and the 9th United States Air Force over Normandy in 1944 is testament to how lethal light flak can be.(25)
Weather and visibility were major considerations for all air operations. This was especially true for aircraft attempting low level attacks against armour without any form of all weather equipment enjoyed by modern day combat aircraft.