The German Rocket Fighter that Dissolved its Pilots Alive

On
July 28, 1944, a flight of P-51 Mustangs escorting a squadron of
B-17 Bombers on a mission over Merseburg, Germany, spotted
something strange in the distance: a pair of white contrails rising
at tremendous speed into the stratosphere. As the contrails pitched
over and dove onto the bomber stream, the fighters broke formation
to intercept. Seconds later, a pair of tiny egg-shaped aircraft
with short swept-back wings flashed by and plunged back into the
clouds, travelling faster than anything the American pilots had
ever seen. It was the Allied air forces’ first encounter with a new
German secret weapon: the rocket-powered Messerschmitt Me-163
Komet, an aircraft so fast its performance would not be
matched for nearly a decade, yet so horrendously dangerous to fly
it would claim the lives of more German pilots in  development
and training than Allied aircrew it took down in combat.

Experiments with rocket-powered aircraft have a long history in
Germany. In a series of increasingly audacious publicity stunts,
during the 1920s automobile manufacturer Fritz Opel experimented
with fitting gunpowder rockets to a variety of vehicles from cars
to railway wagons. These experiments culminated in the construction
of the Lippisch Ente, or Duck, which on June 11,
1928 became the first manned aircraft to fly under rocket power.
Later in the 1930s, aircraft manufacturer Ernst Heinkel undertook a
series of experiments to develop a liquid-fuelled rocket engine for
use in aircraft. Heinkel’s first success came in March 1937 when a
modified He-112 propeller-powered fighter flew under rocket power
for 30 seconds. Heinkel next constructed the diminutive He-176,
which on June 20th, 1939, became the first aircraft to take off,
fly, and land solely under rocket power..

But while Heinkel had high hopes for rocket aircraft, the German
Air Ministry was decidedly less enthusiastic. On first being shown
the He-176, Generaloberst Ernst Udet, Director-General of
Equipment for the Luftwaffe, exclaimed: “You want to
fly with that? It has no wings…those are running boards!”

On actually seeing the aircraft fly, Udet reportedly flew into a
rage, declaring: “That is no airplane, leave it alone! I forbid
you to fly it again.”

Even a demonstration in front of top Nazi dignitaries including
Adolf Hitler on July 3 failed to make any impact, and Germany
entered the Second World War with conventional propeller-driven
aircraft. But the realities of War would soon force the High
Command to change its mind. Starting in 1942 the Royal Air Force
and United States Army Air Force began a concerted strategic
bombing campaign against Germany and occupied Europe, pounding
cities, factories, and other targets round-the-clock. The
Luftwaffe, stretched thin by Hitler’s invasion of Russia
and chronically short on men and fuel, was unable to cope, and so
the call went out for a fast, inexpensive rocket-powered
interceptor that could stem the tide of Allied aircraft.

The aircraft that would become the Komet emerged from
the work of two aviation pioneers. The first was Alexander
Lippisch, designer of the pioneering Ente, who, working
with DFS, the German Research Institute for Sailplane Flight, was
attempting to develop a unique high-speed tailless glider. In 1939,
Lippisch left DFS and took his design to aircraft manufacturer
Messerschmitt, who gave it the designation Me-163. Messerschmitt
soon began experimenting with fitting the 163 with a revolutionary
new rocket engine designed by Hellmuth Walter, who had also
designed the engine for Heinkel’s pioneering He-176. Walter’s
R-1-203 ‘cold’ engine, originally developed as a Jet-Assisted
Take-Off or JATO pod for helping overloaded transport aircraft get
off the ground, reacted concentrated Hydrogen Peroxide with Sodium
Permanganate to generate high-pressure steam, producing around 1000
pounds of thrust.

The result was an aircraft of unprecedented performance. On the
2nd of October 1941 test pilot Heinrich ‘Heini’ Dittmar flew the
prototype Me-163A to a record airspeed of 1003.67 mph, becoming the
first pilot to exceed 1000 mph in level flight. Three years later
Dittmar would fly the improved 163B model to 1130 mph – a record
that would not be beaten by a jet aircraft for almost a decade. The
Komet’s climb rate also far exceeded that of any contemporary
aircraft, being able to climb to an altitude of 39,000 feet in less
than four minutes. This in turn required pilots to maintain a
special low-fibre diet to prevent gas from expanding painfully in
their gut too uncomfortably. Even unpowered the Komet displayed
superb handling characteristics, with pilots reporting the aircraft
to be nearly impossible to stall or spin. And so fast was it in
a  glide that upon being buzzed by a 163A at 300mph, a
startled Ernst Udet is reported to have exclaimed “What sort of
engine has it?”, to which a presumably smug Alexander Lippisch
replied “None.”

Yet despite this blistering performance, the Komet quickly
revealed itself as an extremely hazardous aircraft to fly. Among
its major flaws was its landing gear. For takeoff the Komet was
fitted with a simple two-wheeled dolly which was jettisoned as soon
as the aircraft left the ground, after which the aircraft landed on
a retractable ventral skid. However, if the pilot forgot to extend
the skid or unlock the skid, the impact of landing could cause
severe injuries. Indeed, during the Komet’s development three of
its main test pilots – Heini Dittmar, Rudy Opitz, and Hannah
Reitsch – suffered serious spinal damage and skull fractures due to
hard landings and spent several months in hospital recovering.

But the greatest danger by far came from the Komet’s engine.
Hellmuth Walter’s HWK 509 “Hot Engine,” which powered the
production Me-163B, ran on a combination of two propellants:
“T-Stoff”, highly concentrated hydrogen peroxide;  and
“C-Stoff”, a 30% mixture of Hydrazine Hydrate and Methanol. These
propellants were hypergolic, meaning that when mixed they
immediately and violently exploded. The fact that they were both
colourless liquids meant that handling accidents were common, as in
the case of one unfortunate ground crewman who inadvertently poured
a container of T-Stoff into another containing a small quantity of
C-Stoff. As author William Green recounts: “Before he realized
the magnitude of his mistake his remains had been spread thinly
over the entire test shed.”

This extreme volatility meant that great care had to be taken
when refuelling the Komet, with the propellants being loaded one at
a time and the engine flushed out with water between each flight.
But despite these measures, many Komets and ground crew were lost
to explosions before the aircraft ever left the ground. Even
worse,T-Stoff is highly corrosive and can strip flesh from bones in
seconds. It also tends to react with even the smallest speck of
dirt or organic matter, decomposing violently into scalding steam
and oxygen, meaning it could only be stored in glass or
enamel-lined containers. While Komet pilots were issued with
special acid-proof asbestos flight suits, any landing made with
propellant left in the tanks was likely to end in disaster – as
Mano Ziegler, one of the few Komet pilots to survive the war,
recounts in his memoirs:

A certain Feldwebel Alois Worndl from Aschau, an excellent
fellow and completely reliable flying with the accuracy of a
precision instrument, was chosen from among us pupils to make the
first sharp start in the Komet. “Make it good, Alois!” We shouted,
and then he was off.

…As expected, Alois’ rocket motor cut out at about 6000
metres altitude, and he turned back towards the field, as precise
as ever. Then, without warning, “Sideslip!” The shout came from one
of the group. Alois was much too high to touch down anywhere near
the landing cross! “Sideslip, sideslip!” We all shouted as if he
could hear us, but the Komet shot past us and past the landing
cross – too high, too fast!

Anxiously we watched the Komet touch down far outside the
airfield perimeter, rebound into the air, drop back again like a
brick, then skid into some rough ground and turn over on its back.
A split second later a blinding white flame shot up, followed by a
mushroom of smoke.

On other occasions pilots suffered a fate worse than an
explosion, as in the case of Oberleutnant Josef Pohs, who on one
flight released his takeoff dolly too early. The dolly bounced off
the ground and struck the aircraft, rupturing a T-Stoff line. Pohs
immediately jettisoned his fuel and banked around to make an
emergency landing, but just like Alois Worndl missed the runway,
touched down on rough ground, and flipped over. To the relief of
his watching comrades his aircraft did not explode, but when they
finally reached him and turned the Komet over they were greeted
with a gruesome sight: T-Stoff leaking from the ruptured line had
dissolved the unconscious Pohs alive.