It was stocky. It was cramped. It had a face only a mother could love. And it was armed with enough firepower to pop the turret of a tank. Oh yes. Today we are looking at the Henchel 129, Germany’s often overlooked flying anti-tank gun. Entering service in 1942, it was something of a late arrival for the Luftwaffer.

Its early development had been plagued by problems and it was initially received with some reluctance, but this reluctance would be short-lived. It would never be praised for its speed, but the HS129 was certainly praised for its potent forward firepower and its remarkable ability to shrug off damage and keep its pilots alive.

This was an aircraft built around two things and two things only. Maximum protection and maximum firepower. Be damned to speed. Be damned to agility. Be damned to looks. If it hurts, it works. And for all of its flaws, the HS129 worked. Though it often gets overshadowed by the more numerous ground attack and anti-tank variants of the Juna’s Ju87 and the Meshmmit BF-110, the HS129 nonetheless filled an important role during the Second World War and served with distinction sometimes on both sides until the end of hostilities.

So today we’re going to give this unique looking aircraft the recognition it deserves. Its story is in many ways one of refinement. Constant adjustments to make something awkward work just a little bit more efficiently. And speaking of making things work more efficiently, let’s talk about Opera, the sponsor of today’s video.

Now, when I’m working on a video like this, I usually end up with a browser full of tabs, archives, technical reports, production figures, photo references, distracting YouTube videos, and the inevitable, “Oh my god, how on earth do I pronounce this German word correctly so that my audience isn’t offended?” Now, Opera’s features take this chaotic mess and make it far more manageable.

For example, thanks to the tab islands feature, I can group all of my related tabs and expand and collapse them as needed. All of my HS129 sources stay together in one tab island, my writing references in another, my translation references in a third, and my inevitable distractions are safely quarantined away in a fourth.

Then you also have the split screen feature, which is brilliant when I’m cross-checking sources or comparing photos, that sort of thing. I can keep a wartime flight manual open on one side and a reference photograph on the other. There’s no need to swap windows and that way I don’t lose my train of thought.

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You can tailor the colors, the animations, and the overall look to suit your workspace. My personal favorite setting is a darker, cooler, and calmer theme because I find it best suited to long work sessions. And of course, I set some of my favorite photos that I’ve taken as my wallpaper. Now, I’m honestly surprised at how much I’ve enjoyed using this browser.

Um, I’ve not really been picky on this sort of thing in the past, and I’ve definitely realized the error in my ways. This has genuinely smoothed out my workflow and cleaned things up a lot, especially on the larger research projects that I’m currently working on. So, if you’d like to try it out, Opera Browser is completely free.

You can find the download link in the description and in the pinned comment below. So, thank you to Opera for sponsoring today’s video. And now let’s get back to our flying tank buster. Now the Hener 129 went through some very specific phases of development. Because of this, I’m going to cover all of the design and technical developments of the type first and then we’ll take a look at its service history.

Hello, future Chris here. Uh just a quick disclaimer, this aircraft has a very incomplete photographic record. Photos of various prototypes literally do not exist or survive anymore. And photos of service aircraft are also very scarce or non-existent either. As such, this will be a bit more like a glorified slideshow.

I’ve not decided to do any fancy editing for the sake of fancy editing this time, as there aren’t enough images to make it worth it. So, consider this more of a retro episode in the theme of my older editing style. All right, no more interruptions. Moving on. The story of the 129 begins not in Germany, but over the dusty battlefields of the Spanish Civil War.

For the rapidly expanding German Luftwaffer, Spain provided a harsh but very useful proving ground for its emerging doctrine of closeair support. The JU87 Stooker had demonstrated that a properly flown dive bomber could deliver devastatingly accurate strikes against fixed positions.

However, it also revealed a weakness. The Stooker was illsuited to engaging small mobile targets such as armored cars or dispersed infantry or fastmoving light vehicles. When the Condor Legion needed to deal with these, it relied on older biplanes like the Hineore 51 or the Henchel 123. Their agility made them effective, but their complete lack of armor protection left them dangerously vulnerable to even rifle caliber ground fire.

If the Luftwaffer wanted a true battlefield attack aircraft for future conflicts, it would need something far tougher than a fragile old biplane. It was a line of thought that quickly filtered back to Berlin. In April 1937, the technical bureau of the Reichlift Haft Ministerium or the Reich Air Ministry, which from now on, to keep things simple, I will refer to as the RLM issued a requirement for a purpose-built Schlack Flux, which translates roughly to battle aircraft or attack aircraft. The specification called for a concentrated forward armorament of 20 mm cannons and rifle caliber machine guns along with provisions for small bombs and smoke canisters. The RLM strongly suggested the use of the Argus AS410A engine, a domestically produced 12cylinder inverted V producing 465

horsepower for takeoff. It was far from being the most powerful of engines, but it was readily available in high numbers and more importantly for the worsening geopolitical situation, it required no foreign imported parts. The requirement stressed that the specification was for an aircraft designed for low-level operations where complete air supremacy had already been achieved.

In other words, this was a machine expected to fight the enemy’s soldiers and tanks and not their air force. As such, no rear defensive gun was required. Instead, the RLM demanded comprehensive protection for the pilot and engines, survivability in crash landings, and the ability to operate from improvised frontline air strips.

As a frontline attack unit, the aircraft would inevitably take battle damage and would need to be patched up quickly. As such, ease of maintenance and simplicity of construction were emphasized just as strongly as firepower. Eventually, the RLM sent out their design tender to four manufacturers. Vauavulf, Goula, Hamburg, Flugsb, soon to become better known as Blumman Voss, and Henchel.

Gother quickly withdrew without submitting a proposal. Hamburg submitted a modified version of its asymmetric HA141 reconnaissance aircraft later known as the BV41. Now although this concept offered superb visibility, it was structurally complex, timeconuming to build and powered by a single Dameler Ben’s engine, the DB600 which produced around 960 horsepower.

Now, this engine was powerful certainly, but the lack of twin engine redundancy was considered a major flaw for an aircraft intended to operate directly over the front lines. One hit to the cooling system could bring the entire thing down. Fauvul offered a different approach, which was a modified version of their twin boom Fauv 189 reconnaissance aircraft, which was already powered by two Argus engines.

They proposed shrinking the crew necessel, armoring it, and retaining both the pilot and the rear gunner seated back to back. Even though there was no formal requirement for defense, forward firepower would come from two MG 151 20 mm cannons and two MG7 machine guns with another MG7 for the rear gunner.

Although it was closest to a ready-made solution, which would have been ideal, the FaulVE 189’s size, weight, and complexity raised doubts about how well it could be adapted for hard, low-level combat. Though its twin boom layout was excellent for visibility, it introduced manufacturing and maintenance challenges that were at odds with the RLM’s desire for rugged simplicity.

As it turned out, Henchel would be the only manufacturer to begin with a completely new design. Their proposal, initially designated P46, was to be a compact low-wing monoplane powered by two Argus 410 engines driving two-bladed variable pitch Argus propellers. Forward firepower would consist of a pair of 7.92 mm MG17 machine guns and a pair of 20 mm MG-151 cannons.

The machine guns would have 500 rounds of ammunition each and the cannons 125. These would be mounted symmetrically either side of the fuselage enclosed in metal blisters. The aircraft would also have the capacity to carry four 50 kg bombs or two S125 smoke generators under the fuselage. From the outset, focus was placed on survival.

An all metal construction was to be used with a skin of light stressed metal armored around the central wings with 5 mm of plating. The fuselage was designed around a distinctive triangular cross-section 30 cm wide at the top and tapering to 110 cm at the base. This shape reduced the aircraft’s frontal area and was intended to help deflect incoming fire.

The two spar central wing section was built as a single heavily armored structural box that also housed the engine cells and the three main fuel tanks. These totaled approximately 610 L and were all self-sealing to reduce the risk of fire following any combat damage. The anticipation of combat damage also influenced the layout of the landing gear, which even when fully retracted, still allowed the wheels to protrude slightly from the engine cells.

This would help give better protection in the event of any wheels up landings. Pilot protection was paramount. The nose was made from spot welded armor plates and it contained a so-called armored bathtub to protect the pilot, essentially cocooning him in glass and metal.

These days, it’s a concept that is more regularly associated with the Fairchild Republic A10 Warthog. On the HS129, this armor was 6 mm thick on the sides and 12 mm thick on the front and at the bottom where incoming fire was most likely. The sharply sloped nose theoretically gave the pilot excellent downward visibility for attack runs whilst also providing maximum protection.

In practice, however, this design would initially present something of an issue, as it included a split V-shaped windscreen made of 75mm armored glass. While this offered excellent protection, it severely restricted the pilot’s view. Visibility was not the only thing that was sacrificed in favor of overall protection, and to say that comfort was not a consideration would be a huge understatement.

The cockpit of the 129 was brutally cramped. Henchel had designed it to the exact shoulder width of an average pilot, and they left no spare room. The control column had to be shortened so that it could actually fit between the pilot’s legs, and this would result in unusually heavy control forces for them.

The cockpit was so small that the gun site, which is normally installed inside the cockpit, had to be mounted externally because there simply wasn’t any room left. The radio 2 was too large to fit near the cockpit, and it was installed in the mid fuselage, as well as the first aid kit to treat an injured pilot after a crash landing.

So he basically had to hope that none of his legs was severely injured after an incident, otherwise he wouldn’t be able to get near any medical supplies. The initial evaluations of both the Henchel and Fauler Wolf design proposals were not encouraging. The Argus engines were simply too weak for the weight of armor that was required and performance projections were barely meeting the minimum requirements.

However, Germany had no suitable alternative power plants that were available in quantity, and the RLM still urgently needed a new attack aircraft. [snorts] Thus, despite misgivings, the ministry authorized the construction of three prototypes from each, the Faulov 189s and the HS129. It was in many ways the beginning of an aircraft that was born from necessity.

Faulv got a head start in the prototyping phase because they simply reworked their existing 189 v1 reconnaissance prototype into a ground attack test bed, redesated the FaulV 189 V1B. The conversion involved fitting a new heavily armored central kunicell, narrowing the cockpit area, and rebalancing the aircraft to accommodate the additional weight.

The prototype first flew in early 1939, but the results were immediately disappointing. Although it used the same Argus AS-410 engines as the HS129 would, the FaulV 189 was around 20% heavier, and its structural layout meant that the extra armor severely compromised overall performance. Test pilots at Wretchin noted extremely sluggish responses in roll and pitch, a long takeoff run, and difficulty maintaining energy during maneuvers at low altitude, which is the last thing you want to hear about a prototype of a design that is meant to attack and maneuver at low altitude. The redesign cockpit, which was far more cramped and with poorer downward visibility than the reconnaissance version, further added to pilot dissatisfaction. Unsurprisingly, these issues soon culminated in a forced landing that was caused by poor handling and marginal firepower. While the

prototype was rebuilt with the rear gunner station removed to saved weight and cockpit visibility marginally improved, it was then destroyed after it suffered a structural failure mid-flight which involved both of the rudders detaching in midair on the 8th of November 1940. So that was the end of that.

Despite being lighter than the modified Fauv 189, the Hencher 129 also struggled with the same underpowered engines and its own set of self-inflicted problems. Pilots immediately noted the exceptionally cramped cockpit, which restricted control inputs, and it made the aircraft physically exhausting to fly for extended periods.

Various reports from 1930 and 1940 would criticize the prototype for heavy ailerons, difficult stalling behavior, and inadequate acceleration. Visibility through the thick V-shaped armored glass was described as poor in all directions, particularly downward, which was a serious flaw for a machine that was meant to fly low over the battlefield and shoot down at its targets.

Still, the RLM insisted that development continue. After Henchaw completed a series of intensive testing flights, the V1 was transferred to the Luftwaffer’s main evaluation center at Reglin in July of 1940. Meanwhile, the second prototype, the V2, had flown earlier on the 30th of November 1939, but it was then lost on the 5th of January 1940 when it crashed following what investigators identified as a mechanical control failure similar to issues seen in earlier test flights.

Undeterred, Henchel continued and completed the third prototype which flew on the 2nd of April 1940 and was then delivered to Wlin for evaluation at the end of the summer. During this time, Fauv attempted to regain contention with a refined prototype, the Fauv 189 V6. This incorporated strengthened landing gear, additional armor revisions, and a twin 7.92 mm machine gun installation.

This improved design received the formal designation of Fauv 189C and was intended as the definitive ground attack variant. Its aerodynamic and structure modifications did improve some aspects of its handling, but it was still suffering from excessive weight and its twin boom construction was still considered fragile.

and overall it had inferior survivability compared to Henchel’s compact fully armored center section design. The formal assessments at Relin concluded that while both of the prototypes fell short of expectations, the Fauv 189C’s vulnerability and manufacturing complexity were major liabilities. Cost was an additional factor as well.

The Fauv 189C was calculated to be roughly one-third more expensive to produce than Henchel’s design. As a result, although neither design inspired confidence, Henchel’s was judged as the marginally better option. Thus, with limited enthusiasm, but lacking any better alternatives, the RLM chose the Henchel design as Germany’s future closeair support aircraft.

In July 1940, a contract was issued for 23 pre-production machines that were designated the HS129A-0. Though it must be said the RLM soon reduced this order to 14, reflecting its continuing doubts about the type’s performance and viability. The first HS129A was completed and flown on the 1st of August 1940, beginning a new round of service trials that were intended to determine whether the aircraft could be made into something more operationally useful.

The first seven pre-production aircraft were assigned in autumn of 1940 to Leashvvada 2, an instructional and evaluation unit that was tasked with developing practical tactics and determining the maintainability of the aircraft under field conditions. Service trials of the HS129A confirmed nearly all of the concerns that were raised during the prototype evaluation.

Test pilots described the aircraft as marketkedly underpowered, slow to respond to controls, physically exhausting to fly, and constrained by extremely poor cockpit visibility. Predictably, these shortcomings led to multiple incidents, culminating in a fatal crash on the 16th of December, 1940, in which both the pilot and an onboard mechanic were killed when the aircraft failed to recover from a lowaltitude maneuver.

Despite the continued negative results, the Luftvafa pressed on with further development largely out of desperation. No other dedicated closeair support aircraft was anywhere near production at this point. And with the war expanding across Europe, the need for that aircraft became increasingly urgent.

After the conclusion of service trials, two HS129A0 were dispatched to Shaunfeld for engine and systems testing while the remainer were assigned to Schlashkishvvada 101 at Paris or from this point until late 1944. SG 101 would function as the Luftwaffer’s primary HS129 training unit.

Pre-production aircraft varied slightly in weight depending on the equipment. Generally, they fell between 3,200 kilos empty and 4,300 loaded, but some documents note higher numbers of up to 3,600 empty and nearly 5,000 when fully loaded. Regardless of the exact number, the effect of the underpowered Argus engines was still the same.

With only 354 kmph attainable at best altitude and a modest range of roughly 650 km, the HS129A barely met the minimum RLM performance requirements. Although its relatively low service ceiling of 5,400 m was not a disadvantage for its intended ultra- low-level role, its weak power and labor intensive handling made it dangerous to fly.

Testing and training officers considered the aircraft unsuitable for frontline use in its current form and the HS129A-1 production model was ultimately rejected for this reason. Fortunately for Henchel, a solution emerged in the wake of France’s defeat in 1940. The Luftwaffer suddenly gained access to large quantities of Frenchbuilt Normon engines, specifically the 14M405 models.

These were compact 14cylinder aircooled radials that generated around 700 horsepower. Not only did these offer roughly 235 more horsepower than the existing Argus engines, but their aircooled nature meant that they were significantly more resistant to battle damage. With these engines now available in quantity, Henchel finally had a possible means of overcoming the HS129’s most crippling limitation.

The company’s chief designer, Friedrich Nicolau, initially proposed an entirely new aircraft, the P76, which was built around these new power plants. This design preserved the armored cockpit and general layout of the HS129, but increased the overall dimensions to match the stronger engines. Each engine would drive a threeblade ratia variable pitch propeller, and the new layout promised far better flight characteristics.

However, development of this new design would have taken at least another year. This presented an unacceptable delay as German ground forces were already engaged across multiple theaters and they were planning to open a big front in the summer of 1941 with the planned invasion of the Soviet Union. With no time for a completely clean slate redesign, the RLM directed Henchel to re-engine the existing HS129A airframes instead.

The third prototype, the HS129 V3, would be the first to receive the engines and act as the basic test frame. Because the heavier power plants shifted the aircraft’s center of gravity forward, Henchaw reinforced the wings and repositioned internal equipment towards the tail to rebalance the aircraft.

The modified prototype designated HS129 V3U1 made its first flight on the 19th of March 1941. Flight reports immediately confirmed significantly improved acceleration, climb, and responsiveness. Encouraged by these results, the RLM quickly authorized the conversion of 16 additional airframes to the new configuration, redesating them as the HS129B-0.

Aside from the change in power plant, the B 0 incorporated several important aerodynamic and ergonomic improvements. The most notable change, especially when viewed from above, was the revised wing design. The earlier kinkedked trailing edge and the partially swept leading edge were replaced by a straightedged arrangement.

This reduced production complexity and slightly increased the overall wing area from 28.4 4 m to 29 m. Henchel also responded at last to persistent pilot’s complaints about the obstructive vertical bar that biseected the front windscreen. This was replaced by a single piece armored front panel and the side windows were enlarged to restore at least some level of lateral visibility as well.

Now, while the cockpit remained extremely cramped, certain essential gauges, especially the engine temperature instruments, were moved outboard onto the engine cells. This seems counterintuitive by modern ergonomic standards, but pilots actually found it easier to glance out of the window quickly and look at the dials on the necessels than to twist their necks awkwardly inside the cockpit to sort of look down, over, or between their knees.

Once the conversion of the existing airframes was completed, all subsequent production was standardized as the new HS129B1. This version, though broadly similar to the B 0, received further refinements. This included open cannon troughs in place of the enclosed gun blast tubes, repositioned radio equipment within the fuselage, and a redesigned engine intake.

The nose also received some minor tweaks. Combined with the new windscreen layout, these changes created the distinctive, somewhat blunt facial appearance that became the hallmark of the B series. The standard equipment for the B1 remained unchanged from the original pre-production aircraft. Two MG17 machine guns and two MG-15120 cannons mounted in the fuselage.

However, the B series quickly became the basis for numerous field modification kits, which was beginning to reflect the Luftwaffer’s growing need for aircraft that had anti-armour capabilities. The most common additions were usually underwing ordinance, such as two SC50 bombs or four SD2 fragmentation bomblelets, but far more significant was the optional installation of a 30 mm MK 101 cannon in a vententral gunpod.

When fired in conjunction with the onboard 20mm cannons, this weapon could penetrate early Soviet armor with lethal effect. This upgrade marked the beginning of a sequence of events that saw ever larger cannons gradually installed on the HS129. Impressed by the improved performance and stability of the re-engineed design, the RLM would place an order for 60 HS129B1s.

10 B zeros were upgraded to the B1 standard with a further 50 newly produced. Initial production was carried out at Henshill’s Shaunfeld facility, but as orders increased, manufacturing shifted to the larger Johannes plant to accommodate higher volume. At one point, the RLM issued a provisional order for 250 HS129B1s that would be equipped with sand filters for the North African theater.

But this contract was cancelled before any aircraft were completed, likely due to worsening supply conditions and shifting production priorities as the war situation evolved, but also because production had already switched to a later model. Early frontline use of the B1 quickly exposed several critical weaknesses that had not been fully appreciated during testing.

Most serious were the reliability problems of the NOM 14M engines, which unfortunately proved prone to sudden seizures when operating at high power or in hot weather. Reports from frontline units described frequent in-flight stoppages due to overheating, lubrication failures, and dust ingestion, issues, especially severe on the Eastern front’s primitive forward air strips, and in the harsh conditions of North Africa.

The engine cowlings were therefore redesigned to offer better air flow and protection with shortened exhaust pipes intended to reduce heat soak and prevent exhaust backflow. The original round intakes were replaced with angular intakes, incorporating improved dust filters, which greatly increased the engine’s tolerance to dust and small debris.

The fuel system was also revised, including the addition of pressure regulators and new feeder pumps to counter vapor lock, which was another persistent cause of engine stoppage. A radio direction finder loop was also added to assist navigation to and from low visibility airfields.

Aircraft incorporating these changes were redesated as the HS129B2. The first being upgraded airframes from the original 60B1 order. An initial contract for 250 B2s followed, replacing the earlier order of the B1, with the first examples being delivered in May of 1942. Later production airframes also adopted a simplified radio aerial arrangement with the wire running directly from the fin to the upper fuselage instead of the earlier triangular mast and wire layout.

The basic armament on the B2 changed little compared with the B1, but significant new options greatly expanded its anti-armour capability. One improvement was the ability to carry a single 500 kg bomb on the centerline rack, which was considered vital for hitting reinforced positions and bunkers.

But more importantly, the earlier field kit for the 30 mm MK 101 cannon was replaced with the higher velocity MK 103, which not only had superior armor penetration, but also offered a much larger ammunition supply, typically 100 rounds instead of just 30. Encouraged by the effectiveness of these weapons, Henchel and the RLM also approved the installation of the 37mm BK37 cannon.

This weapon, which was adapted from the Flack 18, and similar to the weapon used on the Ju87G Stooker, was mounted in a streamlined gondola with a 12 round magazine. Its weight and recoil required removal of the fuselage mounted MG17s, but in return, it gave the aircraft a formidable punch against medium tanks.

The addition of this weapon marked a decisive shift in the HS129’s role. It was transforming from a general close support aircraft to a specialized airborne panzer or tank hunter. By late 1942, this transformation became formalized. Henchel began installing the anti-tank weapon kits directly on the assembly line rather than having them installed in the field.

This was in response to the increasing appearance of Soviet built T-34s, KB series tanks, and other Soviet armored vehicles that demanded heavier firepower that the standard 20 mm battery could deliver. On the 25th of May 1943, the RLM issued an ambitious delivery plan calling for 1,635 Henchel 129s to be delivered in a variety of weapon configurations.

Of these, 595 were specified to be equipped with towing cables for the DFS 230 assault glider, theoretically allowing them to deploy airborne troops in conjunction with closeair support operations. However, no documentation survives that indicates that this aircraft was ever employed in this capability operationally, aside from some tests, and it was almost certainly abandoned due to practical difficulties and competing priorities.

Henchaw aimed to produce 40 B2s per month, but actual output fell far short, sometimes barely reaching 20, such as in September of 1942. The major cause of this reduced output at first was the everchanging and often contradictory demands of the RLM itself. At various stages, Henchel was ordered to suspend HS129 production in favor of license building the Jonas Ju88, then retooling for the ME410 and then later going back to Jonas for the new 388.

Each switch required extensive adjustments to the production lines before inevitably needing to be reversed when things went back to the HS129. As the war situation deteriorated, production was also further disrupted by things like Allied bombing raids, chronic shortages of skilled labor, and the increased reliance on forced labor.

apparent from the ethical point of view. It was also with hindsight logistically stupid. Laborers would take any opportunity to sabotage equipment, produce poor quality work that wasn’t obvious, or otherwise find ways to reduce the output of a factory in a covert way that wouldn’t hopefully get them shot.

Even so, Henchel claimed that over 1,000 HS129 B2s had been completed by the end of production in September 1944. This made the B2 by far the most numerous variant, and it accounted for more than 90% of all HS129s that were ever built. It should be noted that although Henchel claimed that over a,000 HS129Bs were produced, it’s a number that is up for a lot of debate.

The final and most dramatic production version, and the one you’re probably watching this video for, was the HS129B3, which was developed in response to growing Soviet armor. This is the variant that has been responsible for a lot of this aircraft’s lingering fame. The B3 has been a favorite in the scale modeling community for years.

It’s inspired a lot of fantastic paintings and drawings and other artworks, and it’s featured in numerous video games and flight sims. All of this is deeply ironic, as only a handful were ever formerly used in operational combat squadrons. But at the end of the day, when you slap a stoning great cannon under the chin of an attack aircraft, it is going to make something of a visual impression.

By 1943, the MK 103 and even the 37mm gun was struggling against the frontal armor of newer Soviet tanks, particularly the KB1S and the new Ysef Stalin series. The RLM therefore authorized trials of a vastly more powerful weapon, the 75mm PAC 40 L46 anti-tank gun. A wooden mockup of the installation was mounted beneath a B2 and tested to evaluate its effects on aerodynamics at Travamunda in May of 1944.

It had less of a detrimental effect than expected. Results demonstrated that the drag penalty was well within acceptable ranges and as a result fully armed prototypes followed. they would benefit from lessons learned from testing this same installation on the Junker’s Ju88. 20 examples of that aircraft had been built with the gun, but they had been troubled by all sorts of problems.

Weight balancing, the cannon’s venting gases causing damage to the airframe skin, its undercarriage, and worst of all, its propellers. And it also suffered from early weapon jams. Now, the development and testing of this weapon for airborne use is a very interesting topic and one that really does deserve its own videos.

So, I’m only going to give us a sort of general overview here, as I want it to not completely detract from the rest of the video that focuses more on the HS129 and not just the big fat gun that it carried underneath it. Compared to the troubled flights on the JU88, the installation and testing of the same weapon on the HS129 went much smoother.

Apart from a small amount of reinforcement being required for the wingle leading edge, the engine cowling and the canopy frame, no major alterations were required to the design. Its installation required the removal of the fuselage mounted 20 mm cannons, but the MG17s were retained for attacking lighter targets.

A new ZFR3B telescopic gun site would also replace the previous gun site to enable accurate longrange fire. The weapon’s massive recoil was managed by an electric pneumatic system and a huge muzzle break. The gases and spent shell casings were ejected from the vententral gun housing after each discharge.

This system had been designed so that even in very steep attack angles, there’d be no risk of the shell casings striking the airframe on its way out. The cannon itself was fed by a drum magazine that could hold 12 shells, plus another one that was held within the gun breach itself, and its fire rate was one shell every 1.5 seconds.

In trials against captured Soviet tanks in the autumn of 1944, the weapon, now designated BK75, proved capable of destroying virtually every target presented, including the heavy IS-2. This was the most powerful aircraft mounted anti-tank gun of the war. It had a muzzle velocity of 932 m a second and it could penetrate up to 130 mm of armor at over 1,000 m.

It could even penetrate up to 95 mm at this range even if the impact angle was at 30°. Weapons tests had exceeded expectations and as a result series production hastily began in July of 1944, but only 23 or 25 as sources do conflict would ever be completed. Just weeks after production began, French factories that were used to produce vital components for the HS129, including its engines, fell into Allied hands following the Normandy landings.

As such, Henchel only had enough parts to produce a score of airframes from what had already been delivered. As a result of the loss of the engine production facilities and the deteriorating industrial situation at home, courtesy of the Allied bombing campaign, all production of the HS129 would be terminated by the end of September 1944.

Now, before moving on to the service history of the HS129, it’s worth briefly talking about the unbuilt HS129C1 and clearing up a couple of things. In 1943, the RLM placed an order for 600 or 700 of this variant with production meant to begin in April 1944. Retaining the MG17 and 20 mm cannons of the B2.

This design would incorporate twin 30mm MK 103 cannons that would be mounted side by side beneath the fuselage. It was also meant to have a different power plant entirely, the Italianbuilt Isotchini Delta 12. This was an inverted V12 which produced approximately 840 horsepower.

Now, a couple of textbooks I found have incorrectly stated a much much higher power output of 1,200, but this engine was never officially rated above 900. So, I don’t really know where they got that power figure from. Regardless of this discrepancy, these engines were still an upgrade in terms of power, and so further additions could be made to the design.

This would be the only variant designed to have rear defense in response to the growing threat of Soviet aircraft on the Eastern Front. It would be equipped with two MG17 machine guns that were mounted at top the fuselage and aimed using a periscopic rear view gun site. And yes, that does mean that the poor pilot would have to worry about performing evasive maneuvers and operating the defensive gun.

Aside from the attempts at defense, the airframe’s external load capacity was also significantly increased. There was provision for bomb carrying capacity of up to 1,000 kg for underwing bomb racks. However, it is unclear as to what specific bombs it was designed to carry, whether it was going to be four sets of the SC250 or two sets of the SC500.

The reason why this is mostly unclear is that delays in engine delivery followed by the Italian armistice in 1943 left this variant without a power plant. Even so, a prototype had been completed and flown in April 1943 using upgraded French engines as a standin and it showed some improvements but not enough to justify costly factory retooling.

As such, this essentially remained a paper project and the type was never put into production. Beyond officially designated variants, numerous HS129s would also serve as weapon testing platforms. Experimental arament trials would include 21 cm and 28 cm rocket installations, 70 mm and 50 mm anti-tank rockets, and even an airto ground flamethrower pod.

But the most unusual and ambitious project involved fitting six vertically mounted 70 mm recoilless anti-tank mortars within the fuselage that were intended to fire downward onto a tank as the aircraft flew over it. From a purely weapon effectiveness perspective, this is a very good idea, as usually a tank’s roof armor is some of its thinnest.

Of course, this weapon would be almost impossible to aim correctly with a human pilot, but the designers had come up with a clever solution. These six mortars were triggered by a magnetic sensor probe, a T-shaped device that was extending ahead of the nose that detected a large metallic mass when it passed beneath the aircraft.

You know, something like a tank. The concept promised high accuracy with minimal pilot skill, which was an especially attractive feature as the Luftwaffer training standards began to decline as the war dragged on. The weapons were tested and the mortars proved to be very effective against captured Soviet armor, but the system itself never saw operational use.

Despite its ingenuity, testing with the system integrated to an airframe revealed that the magnetic trigger was very unreliable and it was considered not worth developing further as the situation for the Luftwaffer was now rapidly deteriorating and they needed more regular airframes sent to the front instead.

Okay, now that the general development of the HS129 has been covered, we can take a look at its service history. But I just want to reassure some people who may have thought that I’ve glossed over a thing or two with the HS129 in terms of its anti-tank capabilities and developments. I am working on a separate video that is looking at German Luftwava tank busters, particularly the 129 and the Ju87.

And some of the details that I would talk about in that video, I would talk about in this video as well. And I don’t really want to feel like I’m repeating information to you. So, some things are being saved for future, so I haven’t ignored it. I’m just putting it in a more relevant video. The HS129B made its combat debut in early May 1942, being operated by Schlack Kash of 1.

These were initially operated over the Crimean Peninsula and the northern shores of the Sea of Azovv. After four and a half months of basic training and a short working up period at the field, its units were thrown directly into combat, attacking Soviet motorized columns, artillery positions, entrenched fortifications, and troop concentrations.

Operational reports describe these opening missions as being surprisingly effective. The HS129 could accurately strike both moving and static targets at very low level, and its concentrated forward armament proved well suited to harassing Soviet vehicles. However, it was also here that the aircraft’s persistent engine reliability issues reemerged under combat conditions.

In the opening weeks of the operation, several aircraft experienced overheating engines, sudden power loss, or outright seizures during their intense low-level combat missions. Some of the first aircraft were lost due to mechanical failure, but a majority of the early losses were combat related. The majority were lost to light and medium anti-aircraft fire as the aircraft’s low-speed attack profile gave Soviet gunners plenty of opportunity to train their guns on their targets.

Even so, Luftwaffer pilots were quickly impressed by the aircraft’s ability to return to base with heavy damage. But despite this ruggedness, the fact remained that the 129s were too often exposing themselves to the advantage of the enemy. Pilots quickly realized that entirely new tactics would have to be developed to suit their unique mission profile. Training was redoubled.

Particular emphasis was placed on extreme low-level flying. And German flack gunners were used in dummy exercises to evaluate different attack strategies. Now, it must be said that all of this additional training and practice was very ad hoc. It was done on a per unit basis and because of that the quality of the training was not consistent.

By midMay 1942, Schlakash one redeployed northwards to support operations in the Kov region of eastern Ukraine. Here the HS129s were employed in constant close support missions, straving infantry positions with their machine guns and cannons and dropping fragmentation bombs on troop assemblies and light vehicles.

German ground commanders repeatedly praised the unit during this time, noting that these low-level attacks had an underappreciated psychological impact on Soviet formations, especially given the overstretched and numerically inferior German forces that were operating in the region. The broad flat stepped terrain around Karkov was ideal for the HS129, allowing pilots to hedge hop towards their targets, using the terrain as much as possible to hide their approach and strike with minimal warning.

In June 1942, the first of the 30 mm cannon kits arrived at the front. Installation normally required the removal of the bomb racks to offset the weight, and initial reactions from the pilots were mixed. Many doubted that a single large automatic cannon would outperform the familiar SC-50 bombs, and some were skeptical of its armor-piercing capability.

But combat experience quickly changed this perception. The MK 101 proved deadly when aimed at the flanks or rear of Soviet tanks, particularly the T-34 and lighter vehicles. Pilots learned to use a shallow oblique attack from the rear quarter, firing a short, precise burst rather than attempting mass fire. Results were sufficiently positive that the MK101 quickly became the standard anti-tank armament for frontline HS129 units throughout the summer of 1942.

The weapon and the nature of its target soon weeded out unsuitable pilots and rewarded the better ones. Though effective, early versions had just 30 rounds of ammunition, which required strict trigger discipline to not waste shells. To reduce the risk of wasting ammunition, many pilots chose to run high explosive and tracer rounds on their 20 mm cannons, essentially using them as a guide, and only firing with the larger cannon when they knew their aim was true.

Some pilots, many of whom became the most successful, would not open fire until they were less than 80 m away from their target. With an attack angle of between 30 and 40°, this required excellent flying skills and near perfect reaction timing. If the pilot didn’t pull out from his attack at the right second, he could risk crashing into the tank that he was attacking.

Even if he didn’t, there was still a risk that the tank could explode and damage the aircraft passing overhead. That’s how close some of these pilots got. But it worked. The methods were risky, but they yielded a high accuracy rate, better armor penetration, and they had the added benefit of utterly terrifying the enemy on the receiving end of it.

The aircraft soon earned itself a strong reputation among both its pilots and the troops it supported. and the HS129 found itself in continual use. In the first 3 months of operating the type, Schlattkashvvada 1 logged over 2,500 combat missions. As the German advance pushed towards the Vular, they then supported the broad drive towards Stalingrad during the autumn of 1942.

But as the weather worsened, operational challenges quickly began to mount. Heavy fog, freezing rain, and vast quantities of ice limited flying time, while attrition steadily mounted from enemy fire, mechanical losses, the weather, and crashes on ice or snow covered air strips.

Throughout the late autumn, the group attempted to support German forces trapped in the Stalingrad pocket, flying low-level attack missions when the weather allowed. Now, as the weather worsened, the use of the 30 mm cannon was abandoned as it was considered too risky to fly so low in the fog. But with a cloud base of between just 100 or 200 m, even using light bombs was risky.

This was further exacerbated by the attrition rate of pilots during this period. Because the situation was becoming critical for the German army, there simply wasn’t time to give new pilots adequate training before throwing them into the fight. Pilot losses and growing mechanical issues eventually forced Schlatkash one to withdraw westward and to avoid being overrun by the Soviet forces.

The intensity of their operations leading up to this was so frantic and conditions so severe that at one point the group could only muster 10 serviceable HS129s. After the catastrophic defeat at Stalingrad, the remaining 129 units were withdrawn for refit and retraining. Some were then redeployed back to the Soviet front with Shellachkashvara 1, but others were sent to North Africa where the rapid Allied advance towards Elammagne demanded urgent countermeasures under the command of Hman Bruno Mer. These aircraft were reorganized under Schlatchkashvata 2. Their first combat mission took place on the 17th of November 1942 when Mia led an attack against a British armored column. Two armored cars were destroyed and German reports describe a degree of panic among British troops who were encountering the HS129 and its formidable cannon armorament for the

first time. However, very quickly, North Africa would prove to be an inhospitable environment for this aircraft to operate. The French built Nomon engines which were never renowned for their resilience to dust or sand or heat elements occasionally encountered in Africa. I have been told became a critical operational handicap.

The sand filters fitted to the HS129s were inadequate and the engines suffered rapid wear, repeated seizures, and clogged compressors. Within only a week of frontline operations, some aircraft already had to be rotated out for emergency maintenance. By the 31st of December 1942, Schlakasha 2 had only seven airworthy machines.

And after heavy Allied bombing in the first week of January, this number fell to just one. The rest of their time in Africa saw little improvement. Mechanics struggled to keep the aircraft operational with limited stocks or spare parts and worsening supply lines. Additionally, the dustladen conditions meant that even with updated filters, the engines often required replacing long before their rated service life.

Reinforcements did continue to trickle into Tunisia and HS129s did carry out further attacks on British vehicle columns, but losses escalated sharply in the face of growing Allied air superiority. The aircraft had been designed for operations under secure airspace. With no defensive armorament and mediocre climb performance, HS129 pilots quickly found themselves at the mercy of Allied fighters.

They did what they could to avoid destruction. Violent evasive maneuvers, dives into valleys, abrupt turns at palm tree height. But these were only partially effective. As spare parts, ammunition, and fuel gradually ran out, and as the axis supply lines completely collapsed, the Luftwaffer withdrew the surviving HS129s to Sicily in April of 1943.

By this time, the steadily increasing number of Soviet tanks on the Eastern Front meant that specialist anti-armour units were now required more urgently than ever. Schlacter 1 had continued operations on the Eastern Front, but was now in desperate need of support. In January 1943 alone, the group had lost 15 or 17 airframes, either destroyed or damaged beyond repair.

Reinforcements eventually arrived and the replenished HS129 units were then redeployed to support Army Group A during the fierce battles of the Kaban campaign. Here the HS129 once again demonstrated its value. Like in Kov in the previous summer, pilots executed extremely low-level attacks against Soviet tanks, anti-tank guns, and infantry concentrations, often striking targets with only seconds of warning.

The aircraft became instantly recognizable to German ground forces who viewed its appearance as a significant morale boost and frontline units frequently requested HS129 intervention by name. Flying from forward airfields only a few kilometers behind the front line, pilots sometimes conducted 5 to 12 sorties per day, responding to immediate calls for air support.

The intensity of these low-level missions often resulted in heavy flack damage. However, the type’s armored tub, reinforced center section, and protected fuel systems allowed many to return despite suffering serious structural or engine damage. Along with the operations in the south, other HS129 units were committed to operation Citadel, the massive German offensive that was intended to eliminate the Soviet salient at Kursk.

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