Two Brothers, One Wing.

by Philippe Ballarini
translation: Mike Leveillard
 

Click on Picture to enlarge

In 1914, Dunne flew his tailless biplane between London and Paris. "L'Illustration"

Arnoux experimented his tailless monoplane at Issy in 1913-1914. It was an idea close to the flying wing. "L'Illustration"

Otto Lilienthal was one of the grands aviation precursors. He is seen here performing a glide from the artificial hill especially built for his tests.

Walter Horten in 1929.

High performance gliders atop the Wasserkuppe the world soaring's Mecca. In the foreground a Rheinsperber. The third Reich encouraged the development of glider flying and soaring which provided a formidable source of pilots for the Luftwaffe. Many pilots were trained there at this apparently innocent looking flight school, including the famed Adolf Galland.

The Horten brothers beside their first glider: the Ho I

Hanna Reitsch famed German aviatrix and hard core Nazi admiring the Ho III.

The Ho IV, a superb flying wing with its 24 meters wingspan.

Reimar Horten, Luftwaffe Officer

The Horten Ho V. The similarity with the Northrop first flying wing prototype is striking.

The Zanonia Macrocarpia grain had inspired in 1908 the creator of the famous Taube. Based on this principle the Horten brothers developed their Parabola.

A Ho IX V1, prototype for the Go 229s. It represents the philosophy of the Horten Brothers: a flying wing glider in its purest form that would be eventually motorized.

A Ho IX under construction. This document depicts the wood construction of this flying wing. (The clamps are aligned on the left). The jet engines are fictitious.

A Ho IX (Go 229) before a test flight. The out of proportion nose landing gear comes from a Heinkel He 177 heavy bomber.

An unfinished G0 22 captured by American troops. Some of those machines were sent to the United States for studies. This photo shows the tubular structure and the wing's profile.

Before evoking the story of the Horten brothers and their strange machines, a review of some background is necessary.

As used as we are to visualize a traditional airplane with a fuselage, we are somewhat taken abashed when looking at a flying wing, and yet, its concept dates back from the dawn of aviation. The benefits of a flying wing become easy to understand when we consider that the fuselage and the tail section produce 30% to 50% of an airplane's drag, thus the reason that purists such as Lippisch or Northrop pursued this concept. The idea of a flying wing is far from being a novelty; it made its appearance at the birth of aviation, and it was a concept adopted by many precursors.

Another essential fact to keep in mind for the comprehension of the Horten brothers' work is to recall the importance that the glider and soaring played in the history of aviation.

While many researchers towards the end of the XIX^th century were trying to create a motorized machine, some purists and grand precursors such as Lilienthal or Ferber believed that a flying machine should be aerodynamically efficient and easy to fly before installing an engine. We must note in passing that Lilienthal had conceived gliders without a tail section before the year 1900.

The Horten brothers would become the virtuosos of the flying wing, testing with stubbornness their machines without neither fuselage nor tail section in gliding flight before even thinking of adapting them with an engine. Obsession? Maybe…Whatever the reasons, they would design flying wings exclusively. No other type of flying machine would come out of their drawing board.

Born at the beginning of the 20^th century, the brothers had developed from childhood a passion for the concept of a machine flying with the purest of qualities. The Versailles treaty of 1919 theoretically banned the rearmament of Germany, particularly by drastically limiting its aeronautical production. This is how glider flying and soaring in Germany came to play such an important part between the wars, not only in the training of pilots but also in aeronautical research. The renowned Wasserkuppe meetings would provide the perfect stage for the advancement of those researches.

It is within this time frame that Walter and Reimar Horten developed, and built their first flying wing before reaching the age of twenty after studying the work of von Prandlt (published in 1918) on aerodynamics with the emphasis on the benefits of the thick wing. They also benefited from indulgent parents that allowed them to transform the family's house living room into a workshop.

During the entire period that preceded the Second World War, the brothers conceived machines having constantly improved performance.

Their first glider, the Horten Ho I, was first flight tested at Bonn-Hagelar in July 1933. Although it was not a complete success, it opened the way for other models, including the Ho IV with a high aspect ratio wing of 24 meters in span, as well as their Ho III that soared to 7000 meters in 1938.

When the hostilities began in World War two, the Horten brothers were of course assigned to the Luftwaffe. Wolfram, the third brother was shotdown over Dunkerque flying a Heinkel He-111, whereas Walter flew Messerschmitt Bf-109 for 6 months. Reimar was also trained on the Bf-109 but he was soon transferred to a special unit preparing for operation "Sealöwe" (Operation Sea Lion) having for objective the invasion of England. For this operation the Luftwaffe had created a special glider unit. More than 80 aircraft, had been assigned to this operation to deliver ammunitions and supplies for the troops of the invasion force, it included five Ho III and two Ho II especially equipped for this mission. The third Reich had once again found in the gliding schools a mean of "feeding" its war machine.

We know now that the tenacity and dedication of the British RAF pilots caused the invasion of England to be cancelled indefinitely. The cancellation of operation "Sea Lion" actually benefited the Horten brothers, permitting them to continue their projects, whereas the glider pilot training center was transferred to Königsberg. They concentrated on the repairs of their damaged gliders, and to the development of new models supported by Ernst Udet.

In 1942, the Luftwaffe advised Reimar that it was searching for an aircraft, which they could use to test a Schmitt-Argus pulse jet engine. They asked him if he thought that le Ho V two-seater could serve that purpose. According to certain sources, this decision came about following reports from German spies in the USA regarding the work of Northrop. The Ho V structure did not permit such mean of high thrust propulsion so the Horten brothers returned to the drawing board and conceived a stronger and larger wing. It would be the Ho VII, a machine equipped with two "pusher" type propellers and a pulse jet engine.

This new venture did not stop the brothers from pursuing their fundamental researches. As Etrich in 1908, they would be intrigued by the "flying seed" Zanonia Macrocarpia, which inspired them for the design of their amazing "Parabola".

But it was wartime and Göering was demanding his "1000X1000X1000". What was that all about? Nothing else than an airplane capable of transporting on a distance of 1000 kilometers from its base, 1000 kilos of bombs at a speed of 1000 kilometers per hour. It was apparently a very unrealistic project for the era, but one that the Hortens (as well as other German engineers such as those from Focke Wulf) came very close to realizing and make operational.

Six months! That was the maximum time allowed to the brothers to have them conceive a prototype, including the assembly methods. It must be remembered that in 1944 the Luftwaffe was already in a desperate state. The glider prototype was ready in a very short time, built of materials consisting of plywood made with a special solvent resistant glue, and some parts of the machine were even made of composite material. Duraluminum had become a rare strategic material in Germany, and its use would have required highly qualified labor, which had been absorbed to serve on the battlefields.

On March 1^st 1944, the Ho IX made its first gliding flight at Göttingen. A second machine had been built to be fitted with turbojet engines. Those turbojets promised for a March delivery were late to be delivered, and when they arrived it was a serious disappointment for the Horten brothers. They had been provided with Jumo 004B of 80 centimeters in diameter, whereas the planned jet engines were not supposed to exceed 60 centimeters! For a more classic machine such as the Me-262, it would not have been an insurmountable problem, but for a flying wing in which the jet engines were to be incorporated, it was a different problem. It would have been necessary to completely redesign the Ho IX, but time no longer permitted such a project. Or, it would have been necessary to substantially increase the wingspan, rendering the airplane unable to achieve the speeds adamantly required by Göering. The Horten brothers therefore resorted to "make do" ingenuity and the machine were ready for test flight at the end of 1944.

Test pilot Lieutenant Erwin Ziller's logbook shows that the first flight with the turbojet engines took place on February 2^nd 1945, but Reimar Horten asserts that December 18^th 1944 was the date of this particular flight.
The RLM (German Air Ministry) had shown satisfaction with the Ho IX, and giving it the code 8-229 it entrusted its construction to the Gothaer Waggonfabrik works. Twenty of the machine's first model was ordered. Several other models had been planned, including two-seaters for training, and night fighters equipped with radar.  We must note in passing that the Horten brothers had developed a special revetment for their Ho IX, made of glue, soot, and charcoal powder, making this already furtive machine practically undetectable with radar.

On April 14^th 1945, the American army arrived at the production factory, capturing the Go 229 (Go for Gothaer the official designation) ending the construction of what had been the first jet propelled flying wing. One of those machines is located at the famed Smithsonian museum.

The Horten brothers did not wait for the arrival of the Americans, and as many of their compatriots, it is in Argentina that they would continue to develop their flying wing. Although they had been geniuses in the conception of airplanes, they had none the less been members of the Nazi party.
They went on to design unorthodox gliders, the Horten XV "Urubu" in particular and a giant transport glider the IAME I.A. 28, but only one of this machine was ever built.
Disregarding their political involvement more or less doubtful, the Horten brothers remain no less the "grand masters" of the flying wing.

Their stubbornness in their researches resulted in the production of a flying wing possessing great flying qualities, beginning with the first one produced to the last one, even introducing the piloting of the machine in a laying down position to reduce the extra drag produced with a normal canopy configuration.

Reimar Horten died in 1994. As for his brother Walter, his life ended in December 1998 in Baden-Baden.

And, what else can we say about the Horten brothers' Go 229 (or Ho IX or Ho 229)?
It was a furtive jet propelled flying wing, operational some decades before the F-117 "stealth" the airplane subject of so much publicity during the Gulf War.

© Aérostories, 2001.

 

 

German flying wings during World War Two

by E.T. Wooldridge

 

 

With the outbreak of World War II in 1939, the outlook for flying wing development improved immeasurably. On both sides of the Atlantic, governments were more than willing to gamble funds and manpower in a search for the right combination of weapons and aircraft that could mean the difference between victory and defeat in the air war ahead. Most of the governments that were at war took a few tentative steps in the direction of tailless fighters, but only one aircraft of the type, the Messerschmitt Me 163, was used in combat. In the United States, only Jack Northrop worked vigorously to build a flying wing, but it was not until a year after the war that the first of his giant aircraft made its maiden flight. In Germany, despite the exigencies of war, the Hortens continued to create a series of imaginative flying wing designs that culminated in the world's first turbojet-powered flying wing. The Lippisch designed Me 163 became the world's first operational tailless fighter.

Following their success with the pre-war Ho III series, the Hortens designed and built the first model officially sponsored by the German government. In the 1941 Ho IV, the Horten brothers doubled the aspect ratio of the Ho III to about 22:1. The glider featured a plywood-covered steel tube inner section containing the cockpit, in which the pilot assumed a semi-prone position to reduce drag as much as possible. This "praying mantis" position, in which the upper part of the pilot's body was horizontally inclined 30 degrees, was restful on long test flights, one of which exceeded nine hours. The wings were made of wood with fabric covering except for the outer six feet, which were made of aluminium. Using a retractable type of skid landing gear, the Ho IV took off on a wheel attached to a wooden skid. After takeoff, the wheel dropped automatically when the skid was retracted. There were no vertical surfaces on the wing, and a complex control system was employed, consisting of dive brakes that moved out at right angles to the wing surface, drag rudders, and three elevons along each trailing edge.

A variant of this aircraft was the Ho IVB, which incorporated a laminar flow airfoil with a plastic leading edge. The airfoil section was based on data obtained from wind tunnel tests of a captured P-51 Mustang fighter. Unfortunately, the Ho NB suffered from bad stalling characteristics and eventually crashed after a spin, killing the pilot. Nonetheless, the basic Ho IV, developed for distance soaring, attained a very high performance level, having been tested in extensive flight trials totalling more than 1000 hours.

Arranged from left to right are models of four significant Horten designs: the pre-war Ho II and Ho III, the 1941 Ho IV, and the single-seat, 1942 Ho V

The Ho V, built in 1937, was the first of the Horten craft designed from the outset as a powered airplane and was the first Horten wing of sufficient size and capacity to demonstrate the commercial or military value of this type. The 1937 Ho V had two side-by-side cockpits and was powered by two Hirth HM 60R 80 hp-engines. This version was rebuilt in 1942 as a single-water and was extensively flight tested in 1943. The Ho V, which in many respects resembled Jack Northrop's N-1M and N-9M flying wings of the same period, had a simple control system with two moving surfaces at each trailing edge, landing flaps beneath the centre section, and spoilers at the wing tips.

A second version of the Ho V was constructed largely of plastic using considerable sandwich material. Plastic sheeting was used for wing covering and rib webs, plastic laminate for main spar booms and stringers, and wood for rib booms. On its maiden flight, this aircraft was badly damaged in a rough landing made in high winds. A third version of the Ho V, a glider tug, was proposed but never built.

Even more unconventional than most Horten designs, the Horten Parabola had a quarter-moon shape with two parabolas meeting at the wing tips. The wing was relatively thick at the centre, and the outer panels tapered to the tips without dihedral. Only one of this model was built, and it was intentionally destroyed after moisture warped the very light structure.

The Ho VI that followed had the high aspect ratio of the Ho IV, but had a wingspan of slightly over 78 feet, 13 feet greater than that of the Ho IV. With an aspect ratio of 32.4: 1, the glider was built strictly for research and was not considered practical for private ownership. According to Walter Horten, the Ho VI behaved extremely well in tests, although it was too advanced for ordinary soaring practice and demanded great skill from the pilot.

Shown on the ground, the Ho VI was a research glider with an extremely high aspect ratio of 32.4:1. Constructed of wood and metal, the aircraft was considered by Walter Horten be the highest performance sailplane of its day.

The bird-like aircraft sails dramatically over the German countryside.

Two models of the Ho VI were built, one of which was destroyed. The other was captured by the Allies and eventually delivered to the Northrop Aeronautical Institute in the United States for study and evaluation.

A more powerful successor to the twin-engined Ho V was the Ho VII, which was equipped with two 240-hp Argus AS IOC engines. Directional control of the aircraft was accomplished with wooden drag bars, mounted on rollers behind and parallel to the spar tip. Moving the rudder pedals moved one of the bars out of the wing tip to cause drag, a concept that proved unsatisfactory in flight. The Ho VII, designed to familiarize Luftwaffe pilots with flight characteristics of flying wings, was considered by Walter Horten to be the brothers' most successful aircraft. Reimar Horten tells the following anecdote concerning single engine performance of the Ho VII:

Goring wanted a demonstration of the single engine performance of the Ho VII. Heinz Scheidhauer flew to Oranienburg (Berlin) and made several low passes in front of the Reichsmarshal. The temperature of the day was 14 degrees F and Scheidhauer was unable to restart the dead engine with the compressed air starter following the demonstration. In preparing for a single engine landing he discovered that the landing gear would not lock down, since the hydraulic pump was installed on the dead engine. With the gear half extended he made a single engine go-around, then discovered that the emergency compressed air gear extension system did not work either, since the air supply was depleted in the unsuccessful engine start attempts. The Ho VII ended up on its belly in the landing.'

Ho V11 under final construction

 

 

Initially constructed as a two-seater, the Ho V was rebuilt about 1942 as a single seater. Two moving control surfaces were on each trailing edge with landing flaps beneath the centre section

Ho Vb

Ho Vc

 

 

 

 

 

 

Dr. Horten adds: "It's a shame. He had an hour of fuel left, and could have flown around for a while, and charged his air bottle with the operating engine." But Goring was satisfied. By March 1945, one Ho VII was completed and undergoing tests, another was nearing completion, and eighteen more were on order.

The most ambitious of the Horten wartime projects was the mammoth Ho VIII, an aircraft with a 158-foot wing span, and six BMW 600-hp engines driving pusher propellers. It could accommodate about 60 passengers in the wing centre section. With an anticipated range of about 3700 miles, the airplane appeared to be slated for the post-war commercial market, but could possibly have been used as a military transport. Construction was not completed by the end of the war. Many years later, Reimar Horten designed another tailless transport for the Argentina Institute Aerotecnico. Faintly reminiscent of the defunct Ho VIII, the I.A. 38 was about two-thirds the size of the Ho VIII, was initially powered by four 450-hp Gaucho engines and had a large compartment beneath the wing centre section that could hold up to six tons of cargo. The aircraft eventually flew on December 9, 1960, but development was hampered by engine cooling problems, and the program was eventually terminated.

The H XVIII was to be a six engined long-range bomber.

 

 

 

 

 

 

 

 

 

Dr. Walter Horten considered this Ho VII with two 240 hp Argus engines to be the Horten brothers' most successful craft. It was to be used to familiarize pilots with the characteristics of powered tailless aircraft. Only one was completed and test flown about March 1945.

 

By far the most advanced Horten design, and the first one intended for combat use, was the Ho IX jet fighter. Patterned after the conventionally powered Ho V, the radical Ho IX first flew as an unpowered glider in the summer of 1944. The aircraft consisted of a welded steel tube centre section and wood for the outer panels with plywood covering, a method of construction that was basic to all Horten craft. Reimar Horten described the construction:

The inexperienced workers available in 1944-45 could more easily be trained to work with wood, as long as the design was kept simple and primitive. Control rods and wires were inside the spar, fuel was kept in the space in front and behind. Fuel resistant glue and varnish were used, and fuel was pumped right into the wood structure without any kind of liners or bladders. Glue could be mixed with sawdust and applied over varnished surfaces to fill imperfections.

The wing skin was up to 17 mm thick; with a more refined construction, 6 mm would have been sufficient. The wood construction had some additional benefits; for instance the aircraft was almost invisible on radar. The wood panels even diffused the returns from the top mounted engines sufficiently to make radar gun sights useless. A second advantage was the minimal damage a 20 mm shell would do when it exploded inside the wing. A hole would be made, and a few ribs damaged, but the aircraft could still fly. A similar explosion inside the metal wing of a Me 109 would deform the wing so that the aircraft could not fly.'

The Ho IX V2 under construction in a 3 car garage

The Gotha Go 229 (Ho IX) as it appeared after capture by United States forces at war's end. The turbojet engines exhausted over the upper surfaces of the wings, which were protected by metal plates. The sturdy tricycle lauding gear retracted into the wind, the centre section of which was built up from welded steel tubing, with the outer section made of wood with plywood covering. Outer wing sections are missing in this photograph

 

 

 

 

 

 

 

 

 

Steel plates protected the upper surface of the Ho IX wing from the hot jet engine exhaust. The entire trailing edge of the wing consisted of three control surfaces on each side, with outer and centre surfaces giving lateral and longitudinal control, and the inner surfaces acting primarily as landing flaps. Directional control was provided by one large and one small air brake flap located above and below the outer wing. The large air brake flap did not operate until the smaller flap had fully extended, resulting in smoother control than with previous systems. Unique features of the pilot's cockpit included a seat catapult escape device and a control stick, the pivot point of which could be adjusted to increase mechanical advantage for high speed flight.

The world's first turbojet-powered flying wing, the Ho IX V2, is prepared f or flight tests somewhere in Germany in January 1945.

The second model, designated Ho IX V2, was completed in late 1944. Equipped with two 1890-pound thrust Junkers Jumo 004B turbojet engines, the world's first turbojet-powered flying wing flew in January 1945. The famous German soaring pilot Erwing Ziller was at the controls. While initial flight tests were encouraging, tragedy occurred after only two hours of accumulated flight time. Ziller was killed during an unsuccessful single-engine landing. Nonetheless, with the enthusiastic support of Reichsmarshal Hermann Goring, preparations were made for mass production of the aircraft by Gothaer Waggonfabrik A.G. Accordingly, the third prototype was designated Go 229 (Ho IX V3) and was built at the Gotha factory. The aircraft was virtually completed when the workshops were overrun by Allied forces, thus terminating any further development of the series. The completed Go 229 was ultimately sent to the National Air and Space Museum in the United States and will eventually be restored. Several other Horten wings were under construction as the war drew to a close, but none reached the flight stages.

The Horten brothers made technical achievements through initiative, imagination, and tenacity. Although none of their designs were used in combat, their contribution to the growing body of knowledge on the intricacies of flying wing design was considerable, and they must be ranked with the leading pioneers in the field.

Like the Hortens, Alexander Lippisch spent the war researching the military applications for tailless aircraft. While the Horten designs were not produced in sufficient quantity to have any significant, lasting impact, one of Lippisch's designs was the most startling and revolutionary aircraft of World War II.

The DFS 194 was built in 1937. Lippisch conducted ground tests with a Walter rocket engine installed in 1940, followed by the first rocket-propelled flight in August of that year. Eventually, the world's first rocket-powered fighter evolved, the Me 163A, derived directly from the Lippisch Delta IVCDFS39.

Originally built in 1937 as an experimental prototype of a tailless fighter, the Lippisch-designated DFS 194 was later modified for installation of 'a liquid-fuel rocket engine. The DFS 194 was subsequently used as a test bed for the Walter engine, flying at speeds up to 342 mph; successful flight tests led to increased priority for development of the Me 163, world's first rocket-powered lighter.

A remarkable accumulation of highly imaginative designs continued to pour out of Lippisch's Department "L" at Messerschmitt during the early years of World War II. Fighters, bombers, and trainers, all tailless, came equipped with piston engines, turbojets, or rocket engines, or combinations thereof. Some reached the model or mock-up stage but none, other than the Me 163A or its derivatives, ever reached flight test.

Alexander Lippisch's work with tailless aircraft during the 1930s led directly to the most revolutionary operational fighter of World War II, the Messerschmitt Me 163 Komet. Shown here is one of the B-series prototypes, the Me 163BV2, which made its first rocket-powered flight on June 24, 1943.

In May 1943, Lippisch became Director of the Luftfahrtforschungsanstalt Wien (LFW, Aeronautic Research Institute, Vienna) where he began research on the development of supersonic aircraft. Efforts centred around the use of the ramjet engine as the propulsion unit. Project P 12 was conducted under the most arduous circumstances, with Allied bombing a constant threat. Shortages of strategic materials and skilled engineering personnel hampered the orderly progression of research programs. Nonetheless, the P12 and P13 reached the model stage, with wind tunnel and free-flight tests showing enough promise to warrant construction of a ramjet-powered manned aircraft.

Project P12, shown in model form, was to be an experimental aircraft equipped with a ramjet engine. Since ramjet engines do not produce thrust at zero speed, the aircraft would have to be accelerated to flying speed either by a "piggyback" arrangement or rocket assisted takeoff.

With the end of the war imminent, the project had only reached the manned glider stage. A full-size glider model of the P13 ramjet interceptor was constructed to investigate low speed characteristics of the aircraft. Designated DM-1, the glider was not finished by the end of the war. However, at the instigation of Dr. Theodore yon Karman, construction of the DM-1 was completed and it was shipped to the United States for testing.

The Lippisch WI-1 was constructed as a glider to test the low speed flying qualities of a ramjet-powered interceptor. Wind tunnel tests were conducted m the United States after the war, but the aircraft was never flight tested.

 

 

 

 

 

 

 

 

The DM-1 was tested in the National Advisory Committee for Aeronautics (NACA) Langley full-scale wind tunnel in 1946. Eight different configurations of the model were tested, with modifications of the wing leading edges, the vertical and horizontal stabilizers, and the control surfaces made to determine lift, drag, and stability characteristics. Initial tests were disappointing; lift coefficient was low, drag was high, directional stability was unsatisfactory, and the craft was considered unsafe for flight tests. In the final analysis, however, after suitable modifications, results indicated that delta wing airplanes with 60 degree sweepback and sharp leading edges could be designed to have acceptable stability characteristics at sub critical speeds.

The DM-1 was Lippisch's last tangible effort for a dying cause . In 1946 he moved to the United States where after a few years of government service, he joined Collins Radio Company as an expert on special aeronautical problems. In 1966, he founded Lippisch Research Corporation and den eloped the X-113A Aerofoil Boat.

Alexander Lippisch died in 1976. He did not have an aircraft company named after him, only one of his designs was produced in quantity, and even it did not bear his name. But his experiments paved the way^- for the thousands of aircraft bearing the distinctive Lippisch imprint that have routinely flue n in the high speed regime originally explored by Lippisch.

German aerodynamicists showed a preoccupation with tailless aircraft during the closing days of WW 2. Representative of the scores of futuristic designs was the Messerschmitt P 111, a fairly realistic looking jet fighter in the 600 mph category.

A general discussion of German designs for tailless aircraft and flying wings must include a brief description of some designs that were still on the drawing board at the conclusion of World War 2 Encouraged by the successes of the Horten series and the spectacular performance of the Lippisch inspired Me 163 Komet, German designers produced a series of futuristic designs in the final chaotic days of the war. If the old maxim that says if an airplane looks right, it will fly right is true, then very few of those unconventional designs would have lifted off the runway. Among the many improbable combinations of sweepback, sweep forward, variable sweep, asymmetrical arrangements, ventral and dorsal fins, and butterfly tails, there appeared a few seemingly practical configurations, some with characteristics that would appear in the post-war designs of other countries.

In the latter part of 1944, the high command of the Luftwaffe issued an urgent requirement for an improved single-engine jet fighter with performance equal to or surpassing that of the twin-engined Messerschmitt Me 262. Specifications required that the new fighter be powered by a single Heinkel/Hirth 109-011A turbojet, have a level flight speed of 621 mph at 23,000 feet, a service ceiling of 46,000 feet, and be armed with four MK 108 30-mm cannons.

Among the more plausible proposals submitted in response to the Luftwaffe requirement was the Messerschmitt P.1111, a wood and metal tailless fighter that resembled a streamlined, sleek Me 163. Powered by the 2866 pound thrust Heinkel-Hirth 109A-O11A turbojet, the aircraft featured wing mounted controls consisting of elevons, inboard split flaps and outboard leading-edge slats, and theoretically was capable of speeds over 600 mph.

The Heinkel response to the request for proposals was a step or two further away from the conventional direction of the Messerschmitt submissions. The Heinkel P.1078 was originally projected in three versions designated P.1078C, B, and C. The P.1078C, the preferred version, was a jet-propelled tailless aircraft with the cockpit situated over the single air intake, with cannon located on each side of the cockpit. The wing tips were drooped like those on Northrop's N-1M.

Other Heinkel designs of the 1944-1945 period included the P.1079, a two-seat night-fighter with two turbojet engines installed, and the P.1080, a single-place tailless fighter built around two ramjets delivering an estimated 3440 pounds of thrust at 621 mph. Takeoff thrust was provided by four solid fuel rockets.

In the same class with the Messerschmitt and Heinkel designs, but a bit more exotic, were the Blohm and Voss P.212 and the Junkers EF 128.

 

 

The Horton Brothers

 

 

Dr. Walter Horten (13 November 1913 - 9 December 1998 Baden-Baden) and Dr. Reimar Horten (12 March 1915 - 14 March 1994 Villa General Belgrano, Argentina), sometimes credited as the Horten Brothers, were German aircraft pilots and enthusiasts, and members of the Hitler Youth and Nazi party.[1] Though they had little, if any, formal training in aeronautics or a related field, the Hortens designed some of the most advanced aircraft of the 1940s, including the world's first jet-powered flying wing, the Horten Ho 229.

 

A Biography

 

Early Lives

Between the World Wars, the Treaty of Versailles limited the construction of German military airplanes. In response, German military flying became semi-clandestine, taking the form of civil 'clubs' where students trained on gliders under the supervision of decommissioned World War I veterans. As teenagers, the Horten brothers became involved in such flying clubs.

This back-to-the-basics education, and an admiration of German avant-aircraft designer Dr. Alexander Lippisch, led the Hortens away from the dominant design trends of the 1920s and '30s, and toward experimenting with alternative airframes -- building models and then filling their parents' house with full-sized wooden sailplanes. The first Horten glider flew in 1933, which by then both brothers were members of the Hitler Youth.[2]

The Hortens' glider designs were extremely simple and aerodynamic, generally consisting of a huge, tailless albatross-wing with a tiny cocoon of a fuselage, in which the pilot lay prone. But the great advantage of the Horten designs was the extremely low parasitic drag of their airframes. They were 'slick' and scalable to high speeds.

 

During World War II

By 1939, with Adolf Hitler in power and the Treaty of Versailles no longer in effect, Walter and Reimar had entered the Luftwaffe as pilots. (A third brother, Wolfram, was killed flying a bomber over Dunkirk.) They were also called upon as design consultants, though Germany's aeronautical community tended to regard the Hortens not as part of the cultural elite.

Walter participated in the Battle of Britain, secretly flying as the wingman for Adolph Galland, and shot down seven British aircraft.[3]

The Horten Ho 229, the world's first jet-powered flying wing

In 1937, the Hortens began using motorized airplanes, with the debut of the twin-engined pusher-prop airplane H.VII (an earlier glider had a mule engine). The Luftwaffe, however, did not actually use many of the Hortens' designs until 1942, but gave enthusiastic support to a twin-turbojet-powered fighter/bomber design, designated under wartime protocols as the Horten H.IX.[4] For their completion of the Ho 229 prototypes, the Horton brothers were awarded 500,000 Reichmarks.[3]

Securing the allocation of turbojets was difficult in wartime Germany, as other projects carried higher priority due to their rank in the overall war effort. Although the turbojet-equipped Ho IX V2 nearly reached a then-astonishing 500 mph in trials, the project was soon given over to the theretofore low-tech aircraft company, Gothaer Waggonfabrik, as the Horten Ho 229 (subsequently often erroneously called Gotha Go 229). The Ho 229 was captured by the U.S. Army at the end of World War 2, in which one of the planes is presently housed at the Smithsonian Institute in Washington D.C.^[1]

The Ho 229 was a fighter jet with great potential, but arrived too late to see service. Among other advanced Horten designs of the 1940s was the supersonic delta-wing H.X, designed as a hybrid turbojet/rocket fighter with a top speed of Mach 1.4, but tested only in glider form (as the Horten H.XIII). Its revolutionary stealth design included a special carbon layer that was able to reduce the radar range detection. The Horten brothers also worked on the Horten H.XVIII, an intercontinental bomber that was part of the Amerika Bomber project.

 

Post World War II

As the war ended, Reimar Horten emigrated to Argentina after failed negotiations with the United Kingdom and China,^[5] where he continued designing and building gliders and one twin-engined flying wing transport, which was unsuccessful commercially. Walter remained in Germany after the war and became an officer in the post-war German Air Force Luftwaffe. Reimar died on his ranch in Argentina in 1994, while Walter died in Germany in 1998.

In the late 1940s, the personnel of Project Sign, the U.S. Air Force's flying saucer investigation, seriously considered the possibility that UFOs might have been secret aircraft manufactured by the U.S.S.R. based on the Hortens' designs.[6]

 

Surviving Aircraft

 

• Unrestored examples of the Horten III and Horten VI sailplanes are displayed at the Steven F. Udvar-Hazy Center facility of the National Air and Space Museum (NASM) in Washington, DC.
• Two of the Horten's gliders built in Argentina can be seen at the Museo Nacional de Aeronáutica located in Morón few miles west of Buenos Aires.
• The turbojet powered Ho 229 V3 brought to the U.S. as part of Operation Paperclip for evaluation is in storage at the NASM awaiting possible restoration.
• An example of the Horten IV glider is located in the "Planes of Fame" aircraft museum in Chino, California.
• A restored Horten IV is also on display at the Deutsches Museum in Munich.

 

References

1.  "Two brothers, one wing", Philippe Ballarini. Aerostories. Retrieved March 16, 2010.
2.  "Hitler's Stealth Fighter", Michael Jorgensen. National Geographic. Retrieved March 16, 2010.
3.  "Under the radar inventions", National Geographic. Retrieved March 16, 2010.
4.  "German flying wings during World War Two", E.T. Woolridge. Century of flight. Retrieved March 16, 2010.
5.  "Revisiting the National Socialist legacy", Oliver Rathkolb. Aldine Transaction, 2004. ISBN 0765805960, 9780765805966. Retrieved March 16, 2010.
6.  Michael D. Swords, "UFOs, the Military, and the Early Cold War" (pp. 82-122 in UFOs and Abductions: Challenging the Borders of Knowledge, David M. Jacobs, editor; University Press of Kansas, 2000

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