Henschel Hs-129 In Detail
By Denes Bernad
Specialty Press/Midlands Books
Review by Ned Barnett
(review copy provided by Specialty Press)
The Henschel Hs-129 tank-killing ground attack aircraft is one of those remarkable wonders/blunders that have always – to me – defined the Luftwaffe. Innovative in concept, this plane is a classic example of a great design that was botched in execution. Pummeled by bureaucracy and political in-fighting; the Hs-129 was nonetheless effective in combat. And most important, it was a classic Axis example of too-little, too-late.
As an aircraft, the Hs-129 has always fascinated me. From the early Profile publications and the contemporary Airfix kit to the later and larger-scale kit by ESCI, this plane has always intrigued me. It had the weapons, but not the power to really make use of those weapons. Limited horsepower forced bizarre (to me) design choices that are part of the aircraft’s charm, and part of the reason it so utterly failed to make a difference in aerial combat. Now, thanks to Denes Bernad and Specialty Press/Midlands Books, I have been able to be reacquainted with this bizarre precursor to the A-10, Su-25 and MiL-24 dedicated anti-tank ground attack aircraft. For the historian, this book focuses on technological development without focusing over-much on operational use; for the modeler, it is pictures and drawings and text that make it possible to create wonderful models of a variety of special-purpose versions of the Hs-129.
I’ll go so far as to say this: If you want to understand German design philosophy (and the equipment shortfalls that influenced that design); if you want to understand how the Luftwaffe’s command did so much (through indecision and constant change-orders) to assist the Allies’ eventual victory – or if you want to build a superbly-accurate model of this aircraft, you need this book!
But before I go farther into the book, let’s look at the plane and its protracted and frustrating development – and a bit, too, on its remarkably small production run.
The Luftwaffe – along with the Soviet VVS and the Italian Regia Aeronautica – had the opportunity to stage a combat dress-rehearsal for World War II in the blood-soaked skies over Spain. Many lessons were learned – some legitimate, some not.
On the “mistaken” side of the ledger, the Soviets “learned” that the biplane was still viable, and put the I-153 fighter into production in 1939 – a lesson the Italians also “learned” before introducing the CR-42. This “lesson” represented a huge step backwards for the Soviets, who had introduced the world’s first successful retractable-gear cantilever-wing monoplane fighter (and the first 300 mph fighter) six years earlier. In 1935, the Soviets had in operational squadrons the I-16, the most advanced fighter in the world. Equally mistaken, the Germans “learned” that the fast medium “strategic” bomber would always get through, without the need for long-range escort fighters or heavy on-board defensive weapons. So they canceled General Wever’s planned “Urals Bomber,” ensured that the Bf-109 was more a long-range intruder than a viable escort fighter, and “protected” their bombers with a few puny rifle-caliber machine guns. Four years later in the skies over Southeastern England, the Luftwaffe learned their mistake – too late to win the Battle of Britain, but still in plenty of time to lose the war.
However, the Germans did learn a few lessons worth knowing – improved versions of the Bf-109 and the Ju-87 were the result of those lessons, as was the value of “terror-bombing” of unprotected cities. Warsaw in 1939, and Rotterdam and Coventry in 1940 were just tactical extensions of Guernica. But an often-overlooked lesson the Luftwaffe learned was the value of a dedicated ground-attack aircraft in the critical army-support role. The elegant Hs-123 biplane proved adequate in this role in Spain, but Germany knew that a bigger, better and more heavily-armed plane was needed (and so did the Soviets, who learned the same lesson and began developing the war-winning Sturmovik). In 1937, the Germans began the development of one of the world’s first dedicated ground-attack machines – a logical extension of the world’s first ground-attack aircraft, the armored and heavily-armed German Junkers J-1 of WW-I. This was the visionary concept. How it was executed becomes the “botched” part of the equation.
Several manufacturers competed for the production prize – but only Henschel started with a clean sheet of paper, and their design won because it most closely met the Luftwaffe’s requirements. The armored ground-attack version of the Fw-189 was a remarkably similar design to the Henschel, but it was bigger – and because it had the same puny Argus 440-horsepower engines – it performed less well. However, even the from-the-ground-up attack Henschel – created with those two one-lunged Argus engines in mind – was underpowered to a remarkable degree.
I’d like to make a brief aside here and talk about the importance of aero-motors in the creation of war-winning aircraft. Too often, the importance of having the “right” engine is overlooked – or just assumed. In the U.S. especially, we had enough engine manufacturers, each striving to build engines to meet specific needs (some big and powerful, some small and efficient), to ensure that we had engines for all military aircraft purposes. Hell, we even powered many of our WW-II tanks with aero-engines – Wright Whirlwinds, for instance – while still building 100,000 planes a year for ourselves and our allies.
Consider radial engines (a comparison I use because the Hs-129 was radial-powered). We started the war with engines in the 1,000-horsepower class which quickly grew to 1,200 horsepower and ultimately almost up to 1,600 – the R-1820 started at about 700 hp in the early B-17s, and wound up at 1,475 hp powering the “Wilder Wildcat” – the Grumman/Eastern FM-2. The R-1830 grew in much the same fashion. A step up, our R-2600 radials went from 1,600 hp in the early B-25s and TBFs up to 1,900 hp in late-war aircraft; and a further step up was the R-2800, which grew during the war from 1,900 to about 2,500 hp – and powered the B-26, A-26, P-47, F4U, F6F and other war-winners. At lower power levels we had engines to power our trainers and utility aircraft, but no American war-built plane had to enter combat with engines rated at below 1,000 hp, even at the start of the war.
The Soviets had a similar range of engines – they never had to face the problem of fielding modern combat aircraft with under-powered engines. The Brits did not have that choice – at least not early in the war – and they had to send into combat planes like the Blenheim, with engines under 1,000 hp, when the Blenheim needed at least two 1,200 hp engines to have a prayer of performing its mission. Compare that sad-sack aircraft to the American A-20 – the Havoc had a smaller crew, a heavier defensive and offensive armament, a larger bomb-load and a longer range. This added performance was thanks to its powerful R-2600 engines, which at 1,600 hp, gave the A-20 a 300-mph-plus top-end speed, even combat-loaded. The British engine problem was due to misguided government policies and a too-small civilian flying industry base to justify creating better radial engines – it didn’t help the Brits that pre-war, American engines were so readily available, as well as so reliable.
The Germans, unlike the Brits, could at least blame the Versailles Treaty for their woes. The cause was different, but the results were the same – a limited selection of mostly old-design (hence heavy for the horsepower produced) and low-powered radial engines. To be sure, the BMW (Bavarian Motor Works) company produced an excellent high-horsepower radial – it powered the Fw-190, for instance – but between the top-end BMW and the very low-powered engines designed for primary and basic training aircraft, the Germans had nothing in the middle. So instead of designing a ground attack aircraft with a couple of 850 hp engines, in 1937 Henschel created their Hs-129 around a couple of 440-hp Argus engines. Even when horsepower was upgraded in the early ‘40s, they didn’t go to 1,000-to-1,200 hp radials – what I consider to be about the functional minimum for this aircraft, considering it’s mission – but did the best they could with a couple of hand-me-down French Gnome-Rhone radials of about 800 hp each.
The US Navy’s new TBF single-engined attack aircraft – which entered combat at about the same time as the Hs-129 – had a 1,600 hp R-2600 engine. The roughly mission-comparable (to the Hs-129) US A-20 two engined ground-attack aircraft, which was designed at the same time as the Hs-129, but which saw combat far earlier, had a couple of 1,600 hp R-2600 engines – twice the power of the revised and upgraded Hs-129 B, which had two hand-me-down French-built Gnome-Rhone 800 hp radials. Is it any wonder that the Hs-129 was defined by its compromises and performed like a dray wagon instead of a hot-rod?
A comparison between the A-20 series and the Hs-129 series is useful. Both twin-engined ground-attack aircraft began as 1937 design studies, both completed production in September of 1944, and both were heavily influenced by lessons from the Spanish Civil War. Douglas first considered a pair of 450 horsepower radial engines for its 7A design, before rejecting that design as being grossly underpowered for the mission. Later in 1937, Douglas upgraded the design to model 7B, which featured a pair of 1,100 hp R-1830 Twin Wasp engines, while Henschel stayed with the 440-hp engines through at least 1940.
The US Army Air Corps was budget-strangled in the late ‘30s, but the French ordered 270 of this potential world-beater as the DB-7, specifying 1,000 hp versions of the R-1830 engine, those these were soon switched back to the more powerful 1,100 hp versions of the Twin Wasp radial. Before the first production Hs-129 flew – with puny 440-hp engines – the first 64 production DB-7s were entering combat with the French Air Force in the anti-tank role. Some of these remarkable first-version of the A-20 survived to the end of WW-II, seeing combat against isolated, cut-off pockets of German forces stranded in France in late ’44 and early ’45.
After these first combat models proved the design’s value, the A-20 series was upgraded again, being mated to the superb 1,600-hp R-2600 engine, ensuring that by the time the upgraded Hs-129 entered combat, its nearest American rival would have exactly twice the base horsepower. Germany knew this was a problem – they wanted to give the Hs-129 an engine in the 1,200 class – but it had none to give. Eventually they settled on an Italian engine design – only to have Italy drop out of the Axis. However, this was in late ’43, at a time when the A-20’s replacement – the A-26 (with more than 4,000 available horsepower in two combat-proven R-2800 radial engines) was already in production.
I haven’t focused on in-line engines – Germany had several good ones, including engines in the right horsepower class for the Hs-129’s mission – but those were all completely committed to more viable combat aircraft and were never considered for the Hs-129. The Daimler-Benz DB-600-series engines were excellent, but they were committed to powering the Bf-110 Zerstorer and the Bf-109 fighter. The similarly high-powered Junkers Jumos were another excellent series of engines used primarily in bombers. The British had an abundance of good inline designs – as well as a few major disasters. While it’s true that engine design flops killed off the Manchester and the Whirlwind, the latter the world’s first four-cannon, 400 mph fighter, the Brits also developed the Merlin and the Griffon – two exceptional engines used in high-altitude interceptors and low-level ground-attack aircraft.
However, the Soviets had production capacity to spare (as did the Americans) – even while relocating their factories to the frozen steppes of trans-Urals Siberia – and had good-quality inline engines that were major improvements over the foreign designs on which they were based. The Soviets were able to power the single-engined ground-attack Sturmovik with a powerful, 1,770 hp Mikulin Am-38F liquid-cooled inline piston engine. America also had an abundance of inline engines – Packard-built Merlins and home-grown Allison V-1710, an often-underrated engine that performed well below 20,000 feet – and, when turbo-supercharged, continued to perform well on up to 40,000 feet. At the time the Hs-129 was being redesigned for the 800-hp Gnome-Rhone, the Allison was reliably producing 1,200 hp.
Another factor often overlooked is production itself. Many historians marvel at Germany’s ability to produce huge numbers of combat fighters, even late in the war – more than 30,000 models of the Bf-109, for instance, were manufactured. However, a closer look shows that this productivity was achieved at a sacrifice – other aircraft were shelved altogether or produced in quantities that would have the Allies laughing in smug self-satisfaction. The Hs-129 – for all it’s flaws – was still a competent ground-attack aircraft. It was capable of destroying tanks at a time when the Panzer forces were being overwhelmed by huge numbers of qualitatively competitive Soviet tanks – but it was never available in quantities sufficient to need.
From 1942 to September 1944 – when production ceased for political reasons – Henschel produced only 1,168 Hs-129s (and of those, more than 100 never left the factory). To put this in comparison, during a single three-month period in 1941 – long before US aircraft production hit it’s stride – Curtiss produced nearly that many copies of the Tomahawk – the British name for early-model P-40s. Britain received so many of these excellent machines so fast that it was able to give 100 to China – mounts for the soon-to-be-legendary American Volunteer Group (the Flying Tigers) and several hundred more to the hard-pressed Soviets, even as they waged a pitched battle with Rommel in North Africa. Focusing merely on ground attack aircraft, Douglas produced 7,098 A-20 series aircraft before production ended in September, 1944 – the same month that production ended for the Hs-129. These A-20-series aircraft were used against the Germans by the French, the British, the US Army Air Corps and by the Soviet Union. They were roughly 100 mph faster than the Hs-129, and could carry roughly twice the bomb load, and could carry that load twice as far (though the British considered it “short-ranged.”). This was not the only Western Allied ground-attack plane – the P-47, the Hurricane and the Typhoon both performed yeoman’s work in ground attack, and the P-51 and Spitfire (though more vulnerable) were also big successes in the ground-attack role. The P-47 could easily carry twice the Hs-129’s ordnance load, well more than twice as far, and at three times the speed – but it wasn’t even a dedicated ground attack machine. For a dedicated tank killer, other than the A-20, we need to look at the Soviet Sturmovik.
Though it had a single engine, the Sturmovik is the most comparable of aircraft to the Hs-129. Both were designed as ground-attack aircraft, and both were initially designed as single-seat aircraft. Both could carry machine guns or auto-cannons capable of defeating tank armor. They had similar top speeds (just above 250 mph) and range (400 miles). Both were heavily armored against ground fire.
However, there the comparison breaks down. The Sturmovik – more formally, the Ilyushin IL-2 – had a single engine with more power than both of the Hs-129’s engines – twice the power, but half the drag. However, the real important factor here was in the production of the two aircraft. As noted, around 1,050 Hs-129s were produced and delivered – roughly 1,000 were eventually distributed to combat units. The story was somewhat different for the IL-2: a total of 36,163 IL-2s were built, making it the single most produced military aircraft design in all of aviation history. If Germany was to have a chance – given that the Soviets were producing more T-34 tanks in a year than all the German tank production of the entire war – then the Luftwaffe needed to procure and issue to combat units the Hs-129 in Sturmovik-like numbers. In the US, a plane built in numbers as low as the Hs-129 would never have been issued to combat units – in those quantities, the logistics of keeping such a small fleet was not considered worthwhile. But the Germans tried to make use of every Hs-129, trying to make dozens perform like hundreds, and hundreds to perform like thousands.
The plane could have been produced in greater numbers – though even 2,000 seems a stretch – but the RLM – the Luftwaffe ministry assigned to order and monitor aircraft production – kept changing it’s collective minds. The stop-and-start-and-stop-and-start priority fluctuation is nothing short of amazing. The Henschel plant was first ordered to switch to Ju-188s, then to switch back to keeping the Hs-129 production line flowing. Later, with 100 machines nearly ready for delivery, the RLM said, “scrap them all – we need Ju-388 strategic bombers.” So Henschel did, though they never got enough machine tools and pattern dies to make even a single Junkers. At best, the Henschel factory worked at 65 percent capacity, though even 100 percent wouldn’t have been enough to turn the tide. Production crawled for nearly three years on what was basically a simple, low-tech, easy-to-manufacture aircraft. Ilyushin produced as many Sturmoviks in the average month as Henschel’s Hs-129s were manufactured and delivered during all of World War II.
In combat, the Hs-129 primarily saw service against the Soviets – however, a few were assigned to North Africa, a few trainers based in France might have flown combat missions against the Western Allies (note – this is pure speculation – the training squadrons were based on France in early ’44, so it may have been that they saw limited combat operations after Overlord, but that’s not been confirmed, at least not yet). And Rumania, which also flew the Hs-129, had a couple of dozen planes still in operation at the time when Rumania left the Axis and joined the Allies – these then flew to the end of the war in service against the Germans.
However, the vast majority of these Hs-129s flew against the Soviets in the 1942-1945 timeframe. In spite of negative comments by test pilots, those who flew the Hs-129 in combat praised it to high heavens. Perhaps it was the heavy armor plate, which helped them survive attacks that would have defeated any other plane in the sky – except, perhaps, for the extraordinarily well-armored Hs-129 – though surviving reports praise the plane’s low-level maneuverability and performance. Apparently, they didn’t mind having the engine instruments mounted on the engines – not inside the incredibly-cramped and superbly-armored cockpit – or perhaps they so enjoyed smashing Soviet armored fighting vehicles (which the Hs-129 could do with ease) that they overlooked all the other planes’ obstacles.
All of which is prologue to my review of the book, Henschel Hs-129 in Detail. This is a great book – useful for those fascinated by mil-tech, and absolutely essential for anyone contemplating the building of a model kit of the Hs-129. I build the old ESCI kit years ago, and now that I have this exceptional book in-hand, I plan to build the modern Hasegawa kit. It should make an interesting complement to my new Eduard IL-2 Sturmovik kit – both are in 1/48th scale, large enough to do justice to these heavily-armed and –armored ground attack aircraft.
I first became fascinated with the Hs-129 when I read the old (late 60s) Profile Publication on this mixed-bag aircraft. When I first opened this book, I thought it would be a “super-Profile” – but I was wrong in one or two important areas. These don’t distract form the book – they define it. Profiles covered design and combat utilization – this new book covers only the design, construction and modification of the Hs-129. There is virtually no mention of combat operations – nor was there any such intent. This book is a technical reference, ideal for the historian or modeler – my lord, between the intense quality of the photos and the many reproduction from factory manuals and Luftwaffe manuals, a modeler who couldn’t super-detail an Hs-129 kit based on this book Just Isn’t Trying Very Hard. In addition, while photos are not there for all sub-variants, the recoilless mortar fired by photo-sensitive sensors would be as spectacular to model as it would be to see it fire. The mention of a flame-thrower-equipped version already has me thinking about ‘conversions.’ There are more, but I trust this is enough to whet the appetite of any normal plastic-basher.
Specifics – 96 magazine-sized pages, probably 3-5 photos per page (most in B&W) – a smattering of color profiles, lots of break-out chart with weights-and-measures, performance specs and related information. The text is useful and informative, the captions on the photos are even more useful – but damned hard for these 55-year-old eyes to read without squinting. Diagrams galore – most from official Luftwaffe publications – show everything worth modeling. Frankly, I can’t wait to get the Hasegawa kit, then re-read this book, making careful notes of everything I want to see in my finished model.
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