The B-2 bomber is the most iconic aircraft in the world, and a symbol
of ...german... military power? Wait,
how can the United States' most sophisticated bomber hail all the way back to World War II?
It was called the Horten Ho 229, and it promised to change the air war for Germany.
A flying wing design, the sleek, tailless aircraft was not designed to be a bomber
like its American counterpart decades later, but rather a fighter aircraft
which would sweep Germany's enemies from the sky. It was an aircraft so advanced that even today
NASA is still trying to figure out how its designers actually solved some of the key
aerodynamics problems it faced with the primitive state of technology at the time.
Flying wings are incredibly efficient designs, but also very difficult to make
fly for one big reason: yaw forces. These are the forces that want to pull an aircraft side
to side as it flies through the air. Aircraft designers have been dealing with this problem
since the dawn of aviation. But if you can master the tailless design, the benefits are
numerous. The tailless aircraft suffers from much less aerodynamic friction, thus making it
more fuel efficient. A tailless plane can thus be made lighter and carry heavier loads. Less
friction also means more speed for an aircraft using the same engine as a tailed aircraft.
For the US though, the real benefit to a flying wing design was the significant reduction in its
radar signature. As the Cold War progressed, the Soviet Union was beginning to counter American air
power with very robust air defenses. The Soviets had begun to network together ground-based radar,
airborne radar, surface-to-air missiles, and aerial interceptors to create a multi-layered
shield that proved too difficult for US planes to crack. Higher flying or faster bombers were
no longer suitable, the US needed something that was too difficult for the Soviets to track.
The design that would become the most iconic American aircraft in history
would end up inspired by Nazi superweapon designs.
Walter and Reimar Horten began designing aircraft in the early 1930s. To circumvent
the ban imposed by the Treaty of Versailles on Germany having an air force, air sport clubs
had popped up all over the country. These clubs lured in aircraft designers and wanna-be pilots,
and would in fact be the very foundation upon which the mighty Luftwaffe would be created.
Future Luftwaffe pilots learned how to fly by first learning how to pilot gliders and sailplanes
created by these sport clubs. These unpowered aircraft circumvented the restrictions in the
Treaty of Versailles, and certainly posed no threat as they couldn't possibly be armed.
However, what the World War I allies failed to see was how it was providing
something far more important for the future German Reich:
experience in both piloting and designing aircraft of various types. The Hortens were quick to
join in the popular pastime of both flying and designing aircraft, and turned to it with such
vigor that they transformed their family's social room into a workshop to build new glider designs.
The two were heavily influenced by Alexander Lippisch, a pioneer of delta-wing aircraft.
Unlike traditional aircraft with wings that stick out from the body, a delta-wing features
a blended body design with the wings being an extension of the aircraft body itself. This
provides significantly more lift for an aircraft by greatly increasing the lift surface area,
and has the benefit of allowing such a plane to carry heavier payloads.
The Hortens adopted Lippisch's delta-wing designs into their own glider, creating the Horten Ho IV
glider. This glider was built in 1941 aided by the experience earned by Walter Horten,
who had become a Luftwaffe pilot and taken part in the Battle of Britain. The body of the glider
was mostly made of plywood and steel covered in fabric, with the last six feet of each wingtip
made of detachable aluminum extensions. To increase the aerodynamic qualities of
the aircraft and reduce drag, the pilot actually laid down on his stomach to control the aircraft,
thus reducing the amount of canopy that jutted up above the aircraft which created extra drag.
The glider was never meant to serve any practical military purpose, and historians suspect that the
Hortens were using German war resources to further their own ambitions as aircraft designers. The two
sought to break speed and altitude records, and some historians believe they were more
interested in their own careers as designers than in creating practical military aircraft.
But when Hergmann Goring, head of the Luftwaffe,
requested designs for a new bomber, the Hortens saw their chance.
Germany had entered the war with a critical deficiency that became obvious after the failure
of the Battle of England. The Luftwaffe lacked strategic bombers, which severely limited how
much damage the Luftwaffe could inflict on England from the sky. Envisioning a second,
successful, Battle of England, the German air force desperately needed big bombers.
Thus Goring sent out requests for a project called 3x1000- an aircraft that could fly
a 1,000 kg (2,200 lbs) bombload 1,000 miles (1,600 km) at 1,000 km/h (625 mph).
This radical design request called for an aircraft that was almost 100 mph faster than
the jet-powered Messerschmitt Me 262, the world's first fighter jet and fastest aircraft of World
War II. That would mean that the plane needed to be designed around powerful new jet engines,
and be as aerodynamic as possible- which perfectly fit the designs of the Horten brothers.
They were confident their flying wing design could satisfy the requirements of the 3x1000 program,
and the use of jet engines would solve some fundamental problems of the flying wing design
which the United States would run into years after the war. While designing their first flying wing,
the Americans would use propeller engines which created dangerous vibrations across the aircraft,
making it very difficult to control. Jet engines however removed this problem altogether.
The two brothers built a series of prototypes they named the Ho 229.
The first of these three was an unpowered glider built specifically to test the aerodynamic
qualities of the design. Rather than use a wind tunnel though, the Hortens had their
glider towed up into the air and released, safely piloting it back to the earth. Next, the brothers
added jet engines to their second prototype, resulting in a successful flight on February 2nd,
1945. Unfortunately engine failure would cause it to crash a few weeks later during a second flight,
resulting in the death of the test pilot. The design however proved to be effective.
As the war turned against Germany the priority shifted away from designing strategic bombers-
what Germany needed was better and faster fighters to chase off the swarms of Allied aircraft
bombing German industry into oblivion. The Hortens envisioned their flying wing designs to work for
both fighters and bombers, and a smaller-scale design could easily fit the role of an advanced
fighter. Unfortunately for Germany, the clock had run out, and Horten's planes would never
take to the skies. Historians believe that at this point, the Hortens were more interested
in being hired by their former enemies than in making German war machines though.
A Ho 229 prototype would fall into the hands of the Allies at the end of the war and be sent
to England for brief study before being turned over to the United States. The British compiled
a 60 page report after studying the prototype and investigating the Hortens, coming to the
conclusion that the brothers were more interested in advancing their designs and setting new records
than actually creating useful tools of war for the Luftwaffe. Reimar Horten had in fact tried to
emigrate to America in 1938 where he hoped to work as an aircraft designer, but the German government
denied him an exit visa due to him previously having access to classified military information.
Despite their prototype ending up in the hands of the Allies, the Hortens would never
find employment with the US or Britain. Instead, Reimer emigrated to Argentina where he would work
briefly in the aviation industry. There could be a number of factors to why the Hortens were
denied a job while the US was busy picking up so many former Nazi scientists and engineers,
but the fact that they had a reputation for shoddy workmanship may have been why.
When assigned to calculate the V2's center of gravity, Walter Horten used steel measuring
tape- but failed to realize that the first ten centimeters had broken off.
This threw the calculated center of gravity entirely off, leading to predictable disaster.
But while they themselves wouldn't find work in the American aerospace industry,
their design would be immediately put to the test.
In the US, flying wing designs were nothing new either. Legendary American designer Jack Northrop
had been experimenting with a flying wing design since 1941. With the US eyeing an entry into World
War II, the American military was concerned with the possibility of Britain falling to the Axis
powers. If this happened, they would need a bomber capable of strategic bombing of German targets
all the way from the American homeland. Thus the Army Air Forces awarded prototype contracts to
Northrop and Consolidated Vultee for a bomber that could carry 10,000 lbs (4,500 kg) of bombs
on a round-trip mission of 10,000 miles (16,000 km). The bomber would have to fly
at a maximum speed of 450 mph (720 kmh), with a cruise speed of 275 mph (443 km/h)
and fly high enough- 45,000 feet (14,000 meters)- to avoid German fighters.
Northrop set about creating several flying wing prototypes, resulting in the XB-35 and
YB-35 line of prototypes. Numerous problems would arise from the design though, including vibration
from the propeller-driven engines causing serious stability issues, and as Germany seemed unable to
invade Britain, the need for such an extreme long-range bomber was temporarily abated.
After World War II though the US would once more be interested in creating extreme long-range
bombers, and Northrop set about perfecting his design, resulting in the Northrop YB-49
(https://en.wikipedia.org/wiki/File:YB49-2_300.jpg).
This time he used jet engines on his prototype, which solved many of the problems with earlier
designs. On October 22nd, 1947 the first YB-49 took to the skies and set an endurance record for
staying aloft over 40,000 feet (12,200 m) for 6.5 hours. Sadly, the second YB-49 was lost on June
5th, 1948, killing both its pilot, Major Daniel Forbes, co-pilot Captain Glen Edwards, and three
other crew members. It's believed that during stall recovery testing the outer wings suffered
too great stress loads and sheared off the body, sending the aircraft plummeting to its doom.
It was during testing of the YB-49 though that the US military began to
notice it had a dramatically reduced radar cross section-
something which despite popular rumors, had never been a focus of the earlier Horten designs.
The YB-49 would ultimately be canceled in favor of the more traditional Convair B-36 Peacemaker
due to a shift in doctrine by the US. The piston engine design of the Convair allowed
it to have greater range and payload capacity than the YB-49, and with the Cold War setting in
the United States desired an airplane capable of reaching the Soviet Union with a nuclear payload.
However, data on the YB-49's reduced radar cross section
would form the idea of what would ultimately become the B-2 stealth bomber.
The B-2 would go on to solve the flying wing design's chief problems-
namely the lack of yaw control. Before the adoption of fly-by-wire controls,
pilots had to use hydraulics to directly affect an aircraft's control surfaces. This could end up not
just being physically exhausting for a pilot, but meant that far less accurate control was possible.
Modern electronics however allowed pilots to fly an aircraft via an electronic interface,
but it was the adoption of a computer that really allowed the B-2 to shine.
An advanced flight computer- the most advanced in the world at the time- would translate pilot
commands across the B-2's flight surfaces and even engines, allowing the plane to perform
maneuvers that would typically require tail rudders and elevators. The precise computer
controls however also allowed for extremely fine-tuned directional changes, which gave
the B-2 the ability to undertake maneuvers far too dangerous for previous flying-wing aircraft.
The B-2 would be the perfect marriage of design and technology, and set the standard for a future
where stealth is increasingly more important than speed or altitude in military aircraft.
Even today, the US military is now contemplating a tailless flying wing design for its 6th
generation fighter program, ushering in a future where tail rudders are a thing of the past.
Now go check out next generation stealth bomber: B21 raider, or click this other link instead!