Le 28 juillet 1944, P-51 pilots of the 359th Fighter Group were escorting B-17s away from Merseburg when someone called out contrails high at six o'clock. Two stubby, tailless shapes came slicing down through the formation faster than anything the Americans had ever seen — and then one of them stood on its tail and climbed away into the sun. The escorts could do nothing but watch.

L'appareil qu'ils venaient de découvrir était le Messerschmitt Me 163 Komet, le seul chasseur à propulsion fusée jamais entré en service opérationnel. Il pouvait surpasser en vitesse ascensionnelle et en vitesse de tous les avions du ciel en 1944, atteignant des vitesses avoisinant les 1 000 km/h (620 mph) alors que les chasseurs alliés les plus rapides peinaient à atteindre 700 km/h.

It was also, by a comfortable margin, the most dangerous aircraft of the war to its own pilots. The Komet flew on two hypergolic chemicals that ignited on contact with each other — and one of them dissolved human tissue on contact. More Komets were destroyed by accidents, explosions and landings gone wrong than by Allied gunfire.

Un planeur avec une fusée dans sa queue

Le Komet est né sur la planche à dessin d'Alexander Lippisch, fervent défenseur allemand de l'avion sans queue. Ses projets, initialement des planeurs ayant établi des records, ont évolué vers l'avion de recherche DFS 194, équipé d'un moteur-fusée développé par Hellmuth Walter et fonctionnant au peroxyde d'hydrogène concentré. Lorsque la cellule et le moteur furent assemblés chez Messerschmitt, le résultat fut un aéronef unique en son genre : un minuscule œuf sans queue, à ailes en flèche, sans stabilisateur horizontal, sans hélice et sans train d'atterrissage conventionnel.

It took off from a jettisonable two-wheel dolly and came home on a retractable belly skid — features inherited straight from its glider ancestry. Everything about it was minimal, because everything about it existed to serve one number: speed.

That number arrived early. On 2 October 1941, test pilot Heini Dittmar took the Me 163A V4 prototype to 1,004.5 km/h (624.2 mph) — at a time when frontline fighters were roughly 400 km/h slower. The figure was so far beyond the state of the art that it was kept secret. On 6 July 1944, Dittmar went faster still, reaching 1,130 km/h (702 mph) in the Me 163B V18, an unofficial record that no turbojet aircraft matched until 1953. He landed that day with most of his rudder shaken away by flutter.

Les prototypes de la série A ont validé le concept ; le Me 163B définitif était doté d'une cellule armée et plus facile à produire, articulée autour du nouveau moteur Walter HWK 109-509. Environ 370 Komets ont finalement été construits.

The performance never stopped astonishing people. Wolfgang Späte, the test-unit commander who flew the first production Me 163B, described an elegant, lightning-fast, easily controllable dart that could intercept any other aircraft in the sky.

Le carburant qui a dévoré les gens

The Walter engine burned C-Stoff — a blend of methanol, hydrazine hydrate and water — in the oxygen-rich exhaust of decomposing T-Stoff, hydrogen peroxide concentrated to around 80 percent. The two liquids were hypergolic: touch them together and they ignited instantly, no spark required. Ground crews used separate, dedicated tanker trucks for each chemical, and one truck had to leave the area before the other approached. Even traces mixing in a drain could explode, and Komets were occasionally destroyed on the tarmac while simply being fuelled.

T-Stoff had a second property that gave the Komet its grim reputation: it spontaneously ignited anything organic — and dissolved flesh. Pilots flew in special protective suits of rubberized fabric, sitting between two auxiliary T-Stoff tanks holding some 120 litres (32 US gallons) of oxidizer, one on each side of the cockpit.

The warning was not theoretical. In late 1943, Luftwaffe ace Josef Pöhs was killed when a failed takeoff ruptured a fuel line; the official account attributes his death to T-Stoff exposure combined with his injuries. Hard landings on the skid were notorious for rupturing residual propellant lines, and a Komet that flipped or somersaulted with anything left in its tanks usually exploded.

The landing itself was an emergency waiting to happen. After burning its propellants the Komet became a glider — one approach, no go-around, ending on a sprung metal skid. If the skid mechanism failed or the touchdown was hard, the impact could compress the pilot's spine; back injuries were a recurring cost of flying the type.

Sept minutes et demie de tonnerre

A combat scramble in the Komet was violent from the first second. The aircraft lifted off its dolly at over 320 km/h (200 mph), accelerated in level flight to around 676 km/h (420 mph), then pulled into a 70-degree climb that no Allied pilot could follow — 12,000 m (39,000 ft) in roughly three minutes. At altitude it levelled off and accelerated to around 880 km/h (550 mph).

Then the clock ran out. The engine's maximum powered endurance was about 7.5 minutes — far short of what its designers had projected. Everything after that was gliding: one or two firing passes through the bombers, then a long, silent, defenceless descent back to base, where Allied fighters learned to loiter and pick the Komets off in the landing pattern.

Test pilot Rudolf Opitz, who delivered one of the first combat Komets to the fighter wing, discovered that even friendly airfields were a hazard — he recalled that when he zeroed in on the field for a high-speed low pass, “long strings of tracer bullets came at me from all sides.” The flak crews had never seen anything move that fast, and assumed it had to be hostile.

Contre les flux de bombardiers

The Luftwaffe formed its only rocket fighter wing, Jagdgeschwader 400, at Brandis near Leipzig, positioned to defend the Leuna synthetic fuel works — one of the most heavily bombed targets in the Reich. The type's first regular combat interception came on 28 July 1944, when two Komets attacked B-17s without scoring. What the escort commander, Colonel Avelin P. Tacon Jr., reported that day set the tone for every Allied encounter that followed.

Pourtant, cette même vitesse qui rendait le Komet intouchable le rendait presque inutilisable comme plateforme de tir. Ses deux canons MK 108 de 30 mm avaient une faible vitesse initiale et n'étaient précis qu'à courte portée ; il fallait généralement quatre ou cinq impacts pour abattre un B-17. Avec des vitesses de rapprochement de plusieurs centaines de kilomètres par heure, la fenêtre de tir était extrêmement réduite.

The best rocket pilot of the war, Feldwebel Siegfried Schubert, solved the problem by sheer marksmanship — three bombers, including a B-17 reportedly downed with just three rounds. His end says everything about the aircraft: on 7 October 1944, hours after his final kill, his engine cut out on takeoff, a wingtip caught the grass, and his Komet somersaulted and exploded.

The final ledger is disputed at the margins but damning in every version. The Komet is credited with between 9 and 18 Allied aircraft destroyed — nine confirmed kills is the commonly cited figure — against roughly ten lost in combat. And through the end of 1944, JG 400 had lost only six aircraft to enemy action but nine to accidents and other causes. The pattern held to the end: the Komet killed more of its own than the enemy did.

L'échec qui annonçait l'avenir

As a weapon, the Komet was a failure — a vast engineering effort for a handful of bombers, flown by pilots who risked being dissolved, blown up or spine-crushed before ever seeing the enemy. Fuel shortages kept most of the roughly 370 aircraft grounded, and in the last winter of the war the Americans learned they could simply route their bomber streams around Brandis.

As a machine, though, it was a decade ahead of its time. Its speeds went unmatched by jets until the 1950s; Japan license-developed it as the Mitsubishi J8M; and captured Komets were studied intently by the victors — Royal Navy test pilot Eric Brown made a point of flying one under power. Germany's other last-ditch rocket interceptor, the vertically launched Bachem Ba 349 Bavarder, était encore plus radicale et encore moins réussie, tandis que les Soviétiques avaient essayé le concept dès 1942 avec le BI-1.

Aujourd'hui, une dizaine de Komets subsistent dans des musées, suffisamment petits pour être stationnés sous l'aile d'un bombardier. À côté de l'un d'eux, l'idée paraît absurde : un œuf aux ailes de bois, rempli de produits chimiques mortels, conçu pour atteindre la vitesse d'un avion de ligne moderne et atterrir en silence. En 1944, pendant sept minutes et demie d'affilée, c'était l'engin le plus rapide du ciel.

Sources : Wikipédia, Aviation History / HistoryNet (Don Hollway), Musée national de l’air et de l’espace du Smithsonian, Warfare History Network