10 Steel Marvels of Aviation
Yes, they made steel aeroplanes
Steel is a strong metal alloy made by combining iron with a small amount of carbon, and it was first produced in usable form thousands of years ago, with early steel production dating back to around 1300 BCE. Heavy and difficult to form into complex shapes, steel seems an unlikely material for aircraft construction. While it is commonly used in small amounts in high-stress areas like undercarriages, using large quantities of steel is extremely unusual. However, there have been times when protection from heat, bullets, or aluminium scarcity (or fear of) forced manufacturers to turn to this heavy yet strong metal. The following brutes were built with more than 10% steel by weight—some significantly more. This list is by no means exhaustive, but we look forward to revisiting this fascinating subject in the future. Here are 10 Steel Marvels of Aviation.
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10: Henschel Hs 129
The Henschel Hs 129, a pugnacious-looking, rather ugly, German ground-attack aircraft of the Second World War, was notable for its extensive use of steel in its structure, primarily driven by its armoured design. Designed to operate at low altitudes in close support of ground troops, the Hs 129 needed substantial protection for the crew and critical components against small-arms and anti-aircraft fire.
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To achieve this, the aircraft incorporated a steel “armoured bathtub” around the cockpit, engine, and forward fuselage. This armoured shell, made from welded steel plates, accounted for a significant portion of the aircraft’s structural weight.
In addition to the armoured sections, steel was used in high-stress structural members, landing gear components, engine mounts, and various fittings. The rest of the airframe utilised aluminium alloys for the fuselage, wings, and control surfaces to offset the weight of the steel armour. Overall, steel comprised roughly 10–15% of the Hs 129’s total structural weight, which is unusually high for an aircraft of its era.
This heavy reliance on steel provided the pilot and vital systems with a degree of protection, allowing the Hs 129 to survive in high-threat environments. However, the steel armour significantly increased the aircraft’s weight, reducing speed, manoeuvrability, and operational range. This trade-off between protection and performance was a defining characteristic of the Hs 129’s design philosophy.
Other wartime German aircraft that used a surprisingly high amount of steel included the Ju 87 and, to a lesser extent, the Me 262.
9: Ilyushin Il-2 ‘Sturmovik’
Another ground attack aircraft that turned to steel for protection, the Ilyushin Il-2 “Sturmovik,” the most-produced combat aircraft of all time, was remarkable for its extensive use of steel compared to most aircraft of its era. At the heart of the design was an armoured load-bearing shell, often referred to as an “armoured bathtub,” which enclosed the cockpit, engine, fuel tanks, and part of the cooling system.
This shell was made of (often crudely) welded steel plates ranging from 4 to 12 mm in thickness. Unlike conventional aircraft,
where armour was added as non-structural plating, in the Il-2, the steel armour was fully integrated into the aircraft’s structure, carrying loads normally handled by aluminium frames.
As a result, steel accounted for a much larger share of the Il-2’s structural weight than in most contemporaries. Estimates vary, but generally about 15% of the total structural weight was made up of steel, significantly higher than the 2–5% typical in fighters like the Bf 109 or Spitfire.
This heavy reliance on steel allowed the Il-2 to withstand intense ground fire and remain flyable after sustaining damage. The penalty was reduced manoeuvrability and performance, but Soviet doctrine prioritised survivability over agility, making the Il-2’s high steel content a defining feature of its design. (Perhaps the biggest Soviet steel monster was the ill-fated Kalinin K-7.)
8: Fieseler Fi 103R ‘Reichenburg’
Desperate times call for desperate measures, but few measures were ever as desperate as the Fieseler Fi 103R. Consisting of a V-1 cruise missile with a cockpit crammed in behind the 900kg warhead, the pilot was expected to point the aircraft at its target before bailing out.
The standard V-1 was fast and cheap, but woefully inaccurate, proving able to (sometimes) hit a city-sized target but not much good against anything smaller. The addition of a pilot was hoped to make the weapon viable for attacking ships or other tactical targets.
Fieseler Fi 103R ‘Reichenburg’
Despite appearances, the Fi 103R was not intended as a suicide weapon. However, the prospect of survival was rated as “most unlikely.” The Fieseler Fi 103, or V-1 flying bomb, was primarily constructed from steel because aluminium and advanced alloys were scarce in wartime Germany. Steel was widely available, inexpensive, and easily formed into pressed or welded parts. This made mass production fast and possible with minimally skilled, and often forced, labour.
Steel also withstood the vibration and heat from the Argus pulsejet, while providing enough strength for catapult launches or bomber drops. Since the V-1 was a disposable weapon, lightweight alloys weren’t necessary. Its steel structure allowed durability, affordability, and simplicity—ideal for a one-way weapon designed for large-scale deployment.
7: Armstrong Whitworth A.W.41 Albemarle
The Armstrong Whitworth A.W.41 Albemarle had its roots in a far-sighted specification for an aircraft that could be easily manufactured by non-aerospace manufacturers. Conceived as a medium bomber but ultimately relegated to transport and glider-tug roles, its most distinctive quality lay in its construction. Unlike many contemporaries, the Albemarle was built with extensive use of steel tubing.
This decision was born of necessity, as aluminium was prioritised for frontline fighters. The Albemarle’s fuselage employed a welded steel-tube framework, over which metal and plywood panels were affixed. The approach reflected a pragmatic balance of resource management and industrial adaptability, ensuring production could be undertaken by firms with limited aeronautical experience.
In service, the Albemarle proved workmanlike rather than inspiring (though it notably featured a tricycle undercarriage). Its steel skeleton granted robustness, but it came at the cost of additional weight and complexity. Performance as a bomber was modest, yet its utility as a glider tug and transport was quietly invaluable, particularly during airborne operations in Europe.
The Albemarle thus occupies a peculiar niche in aviation history. While overshadowed by sleeker, faster contemporaries, its steel-based design underscores wartime Britain’s capacity to adapt materials and methods. Not glamorous, but steadfast, it symbolised the wartime ethos: functional engineering shaped by constraint, and endurance achieved through ingenuity. It is likely the Albemarle would have been a far bigger deal if they hadn’t got it so right with Mosquito.
6: Sopwith Salamander
The Sopwith Salamander was developed in 1918 as a ground-attack derivative of the successful Sopwith Snipe fighter and was notable for its use of steel armour. Sopwith Camel fighters had been used with great success as ‘trench fighters’ since late 1917, but losses, mainly to ground fire, had been heavy.
The Salamander was therefore designed to survive sustained small-arms fire while attacking enemy trenches. Utilising the wings and tail of the Snipe, the Salamander featured an armoured box made from a steel plate between 6 mm and 11 mm thick, containing the pilot and forming an integral load-bearing part of the forward fuselage.
The armoured steel box itself weighed 275kg, and steel accounted for more than 35% of the overall aircraft weight—an extraordinarily high percentage for the era. By comparison, most contemporary fighters used less than 5% steel. Initial plans to include forward- and downward-firing machine guns were abandoned due to the difficulty of aiming them.
Unfortunately, problems encountered with armour becoming distorted during the hardening process delayed production, and of the 1400 ordered, only 37 Salamanders had been built by the Armistice. Ultimately, a credible total of 497 examples were built, and some served into the early 1920s.
5: Budd RB-1 Conestoga
The Budd RB-1 Conestoga was conceived in the exigencies of wartime, when America’s demand for transport aircraft strained aluminium supplies. In response, the Budd Company, better known for railway carriages, ventured into aviation. Their proposition was audacious: to construct an all-steel cargo aeroplane, in defiance of conventional material practice.
The fuselage, fabricated from stainless steel panels, embodied the firm’s metallurgical expertise. Welding largely replaced riveting, a technique adapted from railway engineering. This gave the Conestoga a singularly robust, but very heavy, frame. The emphasis on steel symbolised industrial ingenuity under resource constraints.
Budd RB-1 Conestoga
Operational assessments, however, revealed limitations. The steel made the aeroplane markedly heavier than its aluminium contemporaries, reducing payload efficiency and complicating handling. Nevertheless, the Conestoga’s high-set tail and capacious rear-loading ramp provided innovations later echoed in post-war transport types. Though only a modest number were built, its design choices proved instructive. But by the time the RB-1 flew in late 1943, aluminium supplies had improved, making the steel design unnecessary.
The Budd RB-1 remains a fascinating episode in aeronautical history. It demonstrates how wartime necessity could redirect entire industries, and how steel—so central to shipbuilding and locomotion—briefly entered the skies. Though not a success in service, the Conestoga embodied bold experimentation in metal and method alike.
4: Bristol 188
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