The Junkers Ju 87 Stuka dive bomber remains one of the iconic weapons of World War II. Images of bomber in screaming dives, its talon-like landing gear poised below its sharp nose, created a terrifying international impression of Germany’s Blitzkrieg onslaught from the attack on Poland in 1939, through the battle of France in 1940, and the invasion of the Soviet Union in 1941. The Stuka blazed a trail for German success on the battlefield and became the icon of early tactical air support.
As the war progressed, Allied airpower advanced and the Stuka squadrons could no longer operate unmolested. Consequently, the German dive bombers mostly disappeared from the skies over Western Europe, but they continued their work on the Russian front. By 1943, Stuka pilots were finding it increasingly difficult to perform in the dive-bombing role in the East as well. Even so, German forces needed help in fighting the ever-increasing amounts of Soviet tanks. A wide range of aircraft were considered for anti-tank duty, and the Stuka was one of the top candidates.
A prominent and highly decorated Stuka ace named Hans-Ulrich Rudel was a proponent of using the Ju 87 as a tank buster. Rudel had already destroyed several Soviet tanks using the 20mm MG 151 high velocity cannons mounted in the wings of his Ju 87D-5. The next step was to equip the Stuka with a more powerful weapon for use against armored vehicles, and this became the Bordkanone BK 3.7cm gun, adapted from the successful 3.7cm Flak 18 AA gun made by Rheinmetall.
Birth of the “Kanonenvogel”
Tests of the new anti-tank Stuka were conducted during the winter of 1943, using a Ju 87D-1. A 37mm gun was hung under each wing in a specially constructed pod. The gun pods were bulky and clumsy looking (each pod weighed 600 pounds), but they did turn the Stuka into a potentially effective tank killer.
The Bordkanone BK 3.7cm guns offered a relatively high velocity weapon — a 3,700 fps muzzle velocity (maximum) firing armor-piercing ammunition with a tungsten steel core. Ammunition capacity was low, and to ensure a kill the pilot needed to target the thin top and rear armor of the enemy vehicle.
Hull top armor for a Soviet T-34 was 20mm thick, while the turret top had 16mm of protection. T-34 hull side armor was just 40mm, but the upper portions of the side armor were sloped at 41-degrees. The BK 3.7cm guns could defeat this armor plate, but accuracy, range (no more than 400 yards) and angle of attack were very important.
A handful of the new “Ju 87G” models were available for Hitler’s massive Kursk offensive in July of 1943, and they instantly proved their worth. There were never enough of the tank-busting Stukas, and the anti-tank Staffeln were in constant action against hordes of Soviet tanks until the very last days of the Reich (only about 175 of the Ju 87G-2s were built).
Targets ranged from Soviet tanks and self-propelled artillery to trucks and barges, to artillery emplacements and bunkers. The entire Eastern Front was a target-rich environment, and the Kanonenvogel flew an exhausting schedule with many missions per day from rough forward fields. General Ferdinand Schörner praised the tank-busting Stukas and said: “Rudel alone replaces a whole division”.
As for Rudel, his combat record is almost beyond belief. He was credited with 519 tanks destroyed, and he claimed a total of more than 800 vehicles of various types destroyed. He also accounted for the destruction of 150 artillery pieces as well as four armored trains. Along the way, he received credit for nine aerial victories over Soviet aircraft. He was shot down multiple times and wounded five times. In February 1945 he had his lower right leg amputated but soon returned to flying. At the war’s end he flew to the West and surrendered to American forces. Despite intense Soviet demands to send Rudel to Russia for imprisonment, U.S. officials refused to turn him over.
Thoughts from the Master Tank-Buster
As the U.S. was developing the Fairchild Republic A-10 Thunderbolt ground attack aircraft during the early 1970s, American officers brought Hans-Ulrich Rudel to the USA to provide his expertise from attacking Soviet tanks from the air. His WWII experiences were a primary source of information on fighting the Soviet/Warsaw Pact armored formations stationed across the lines from NATO forces in Europe.
Live The Armory Life. The latest content straight to your inbox plus an automatic entry to each of our monthly gun giveaways!
U.S. Army Colonel Ray Bell led a discussion group with Hans-Ulrich Rudel during May 1978, and the following are excerpts of their question-and-answer session (with Rudel using an interpreter):
Colonel Bell: “The last time Rudel was in this country, I think he really amazed us in telling us what his tracking time was with guns. He said it was one and a half seconds, and, of course, most of us are used to thinking about four, five, six, seven seconds tracking time associated with dive bombing. I think our first reaction was that he was exaggerating. But after a lot of questioning on that point and on the tracking times and what average pilots were getting and so on, I came to the conclusion that he was telling the truth and that he, in fact, could execute a hard maneuvering approach basically alternating from one wing, from standing on one wing tip to the other during his approach to a tank, at say thirty to fifty feet altitude, snap out, wings level for one and a half seconds, fire and go off into his maneuvering climb out.”
Rudel (through an interpreter): There were a lot of Stuka wings and squadrons and so forth, but there were only two units that had cannon-equipped aircraft; that is with the 37-millimeter cannon under each wing. Each aircraft had two 37-millimeter cannons hung under the wings, one on each side, and they had a clip of six shells in them for each side, a total of twelve. They were supposedly synchronized to fire two shells out at the same time to keep it symmetrical when they were firing.
The two wing-size units’ (Geschwader) nominal strength was 150 aircraft Geschwader 2 and 77 had the cannon-equipped aircraft and each of those units had one enlarged squadron that had the cannon-equipped aircraft. Each on-line string in the field ran about 15 aircraft each, so there were only, at any given time, about thirty Stukas that were cannon-equipped at a time. There was also another unit that was equipped with Hs-129’s. It was a group-size unit, and it had at its inception sixty-eight Hs-129’s, which was a twin-engine aircraft with a belly-mounted 30-millimeter cannon. It was a Mark 101 and later a 103 Mauser, which are similar to the Oerlikon KCA some of you may be familiar with. It carried 30 rounds of 30-millimeter ammunition. All of these used a tungsten carbide penetrator.
Following is further detail acquired from the interview with Rudel.
Size of Ju-87G attacking formations: Colonel Rudel says that going out with a group of more than five to six airplanes was simply nonsense. They just got in each other’s way, and they started attacking the same tanks and there was no point to it. So, he favors tactical formations of no more than five to six. He is talking here about the cannon-equipped aircraft, which you should realize was an extraordinarily un-maneuverable airplane. It was really a marginal war plane. It was a very heavily overloaded Ju-87. It was right at the maximum limit. It was considerably more limited in top speed than a normal Ju-87 which was not known for its blinding speed, and secondly it was quite un-maneuverable. In general, I think, they were limited to maneuvers of less than three g’s with this airplane. So, you can see what kind of hindrances they were working with, but the effectiveness of the gun was so critical because it was the only thing they had that really worked against tanks. They were willing to take all these disadvantages plus a very poor handling aircraft just to have the gun.
Valuable recon: I was referring to the very valuable reconnaissance he was doing, a lot of that was gained on these first morning flights. He would be in touch by whatever means he could either through a radio tank equipped with an equivalent of a forward air controller or, on occasion, as he has described in his book, he actually wrote out a note on a knee pad and enclosed it in a metal capsule and then dropped it on a battalion commander’s tent in order to communicate with him that there were tanks in the next village. This was invaluable information. A lot of this was derived from these first flights of the morning, which he called meteorological flights.
Fuel and flight time, closeness to the front of the airfield: If he had had more fuel on board and more range, he would not have used it to move his fields further back 50 or 60 kilometers, but he would have used it in the target area for more search time because that was invaluable to him. He would have liked to have stayed the same distance, the 50 or 60 kilometers, because of the matter of time — time to respond. In case they got an emergency request, or when there was an attack on the front, he wanted to be able to respond in what he thought was a reasonable time, and to go much further back than 50 or 60 kilometers would just take too much time to get there. You can calculate for yourself what he is talking about because the Stuka had a cruise speed of something like 140 knots or so.
Experience: He says that the real reason that he got to be good was experience. Experience with sortie after sortie after sortie. The Russians generally were shot down after 20 or 30 missions and never had a chance to get the experience. He says very modestly, and I think he is probably falsely and incorrectly modest, that he was not any better than the other pilots, it is just that he flew so much longer (2,530 ground-attack missions, all on the eastern front).
Could you have operated in the West? He says he would have to answer that question with a flat “no”. They could not have operated in the west because the air superiority of the Allies was simply too overwhelming. Keep in mind that it was not just a quantitative thing, it was also due to the fact that the really first-class pilots of the Luftwaffe by 1943 were pretty much wiped out. Earlier than 1943, of course, as you know over northern France, and so on, the Luftwaffe more than held its own and there was no such air superiority. But after 1943 and by the time of Normandy they had both the quantitative losses and much more importantly the good pilots were gone. Therefore, they did not have the situation of necessary air superiority and therefore the Stukas could not have operated.”
Sherman tanks: He said the Sherman tank burned much more beautifully than the T-34. The T-34 was one of the finest armored tanks of its time.
Tank identification: The pilots were under constant instruction on tank recognition, and always being brought up to date on the very latest Russian models and the very latest German models. He himself in his career thinks that he fired on friendly tanks once or twice; fortunately, without lethal results. Once he remembers he fired at a tank and he happened to be shooting a little high and hit it in the turret which he did not penetrate completely, and immediately a helmet popped out. He was still watching to look for the results and he saw by the shape that it was a German helmet.
Aiming points on tanks: For specific tanks did they aim for specific points that were vulnerable? To make it quick I will just give you the gist of the discussion at lunch. Colonel Rudel said this was one of the great differences between the gun he worked with and the new uranium round. The round he worked with was not particularly incendiary, and so you had to hit specific areas, preferably always the area that had the ammunition. In fact, they would aim to hit within 10 centimeters of an aim point to really get assured destruction. They were talking about tiny vulnerable spots because of the difficulty of getting a visible kill. Remember, they only got credit for kills that could be seen burning or exploding.
Firing range: 200 meters for Rudel, and less experienced pilots would shoot at 400 meters.
Jinking: Rudel said there were only two possibilities: either you jinked constantly and very hard coming in and used just the tiniest amount of tracking time to fire and get out; or, if you did not have the experience: you could not fire and hit from such a jinking approach and tried to come in smooth and level, he says then you would get shot down. That is all there was to it. If you jinked hard and were good at it, then you could survive. Now, not everybody could hit from such a jinking approach with such a tiny amount of tracking time, but with experience you could do both and get good hits.
Attacking from rear: He said they normally did not change their attack direction because of the presence of flak. They preferred to attack from the rear. For them there was a bigger vulnerable area from the rear into the engine or into the back of the turret. If because of where they were and they wanted to attack directly, the other preferred attack was from the side. That was harder because the vulnerable area into the munitions from the side was quite a bit smaller, but they would attack on occasion from the side and try to aim for just that spot where they knew they could get into the munition containers.
About the dangers of flak: He said if you ran into some place where everybody was shooting everything, you were going to take a lot of hits. Each hit might not be that dangerous; he came home often with 50 hits in the airplane. It was not uncommon at all, but if one of those was in the radiator he had seven minutes to land. But he says you never know what the exact causes were, and which was the most dangerous, whether it was the specialized flak or the ordinary machine guns. But certainly, ordinary machine guns could bring down Stukas, particularly with these hits in the radiator. That is what they were most afraid of. Furthermore, he says it was very dangerous for them, and very uncomfortable when the flak would fire without tracer. When they fired with tracer, it was great. You could always evade and go up in altitude, but if they were firing without tracer you were flying along fat, dumb, and happy, thinking nobody was shooting. It was very dangerous. There is an interesting point for tactics of anti-aircraft. Since everybody shoots with tracer, tracer is the right way to do it.
Examining the 37mm Bordkanone
An ETO Ordnance Technical Intelligence report from June 1945 reviewed the 37mm guns of a Ju-87G captured in Czechoslovakia. The following is the U.S. report on the aerial anti-tank gun that killed so many Soviet tanks in WWII.
General: Two 37 mm Aircraft cannon were found on a German plane, type JU 87. The cannon were suspended one under each wing and each in a streamlined metal casing. The workmanship on the casing offers every indication that this mounting is experimental. The gun is heated and recoil operated with pneumatic and electrical controls.
Mounting: The portion of the casing housing the recoil mechanism is firmly fastened to the wing of the plane by two hangers. The point of balance is located at the front hanger.
Heater: A gasoline heater is located at the front of the streamlined casing, which is so constructed that part of the heat is deflected towards the gun and part towards the recoil cylinder. The heater is controlled by a thermostat located on a control board mounted in the wing directly above the cannon. This board also contains a fuel pump for the heater and various electrical devices necessary for the function of the cannon.
Firing Mechanism:
a. The cannon feeds from the right side and is of the recoil operated type, firing from a closed bolt. The sear lever is located near the front trunnion on the right side of the receiver and is operated pneumatically. The air valve is controlled by an electric solenoid. The air bottle, of standard German type, is rigidly mounted in the wing of the plane and is recharged by means of a “quick-break” connection placed in the wing.
b. There is no provision to charge the cannon or place it in battery other than by manual operation. The housing is constructed in such a manner that, by the removal of three pins, a portion of the housing is swung open, giving easy access to the bolt handle.
c. There are two extended chutes, one on each side of the cannon. The one on the right side contains the loading tray and the one on the left the ejection tray. When fully loaded the cannon has 12-round in the loading tray. This ammunition is loaded in 6 round clips. The clips are constructed in such a manner that they can easily be attached to each other.
Tube: The tube appears to be the same as that of the 37 mm AA Gun (3.7 cm Flak 18). It is easily removed. It is fastened to the tube extension by interrupted threads and when in place is kept from turning by a spring-loaded bar lock located at the front of the receiver. To remove the tube, the tube lock is raised (can be done easily by hand), the tube turned 1/6 turn counterclockwise and pulled out.
Conclusion
The Junkers Ju 87G, particularly in the hands of a remarkable pilot like Rudel, truly was a revolutionary weapon. In fact, it clearly heralded the future mission of the A-10 Thunderbolt. But, the weight of Allied air superiority and the flailing state of the German war effort ensured even it could not turn the tide of World War II.
Editor’s Note: Please be sure to check out The Armory Life Forum, where you can comment about our daily articles, as well as just talk guns and gear. Click the “Go To Forum Thread” link below to jump in and discuss this article and much more!
Join the Discussion
