Horten Ho 229

Horten Ho 229

Hitler's Stealth Fighter/Bomber & Other Horten Aircraft

American & British Intelligence Documents

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Horten Ho 229 Hitler's Stealth Fighter/Bomber & Other Horten Aircraft

American & British Intelligence Documents 101 pages of United States and British intelligence documents covering the development of aircraft designed by the brothers Reimar and Walter Horten, including the Horten HO 229. Recently this plane has also been called "Hitler’s Stealth fighter", even though the plane's stealth capabilities may have been incidental. An additional United States intelligence report shows that the Japanese were developing technology that was much more explicitly stealth than what was applied to the Horton Ho 229. The Horten Ho 229 is known by several different names. The Horten Brothers called the plane the H.IX, so it is often called the Horten H.IX. Reichsluftfahrtministerium, the German Ministry of Aviation, gave the plane the identity Ho 229. At times it is referred to as the Gotha Go 229, due to the German manufacturer chosen to produce the plane, Gothaer Waggonfabrik. According to William Green, author of "Warplanes of the Third Reich," the Ho 229 was the first "flying wing" aircraft with a jet engine. It was the the first plane with design elements, which can be referred to as stealth technology, to hinder the effectiveness of radar to detect the plane. In 1943, the head of the German Luftwaffe, Reichsmarschall Hermann Göring, presented to the German aircraft industry what is known as the "3 X 1000" goal. Goring wanted a plane that could carry 1000 kg of bombs (2,200 lb), with a range of 1000 km (620 miles), at a speed of 1000 km/h (620 mph). The Horten Brothers had been working on flying wing design gliders since the early 1930's. They believed that the low-drag of the gliders they made in the past could be the basis for a craft that would meet Goring's demands. The H.IX's wings were made from two carbon injected plywood panels adhered to each other with a charcoal and sawdust mixture.

In 1943, Göring awarded 500,000 Reich Marks to the Horten Brothers to build and fly several prototypes of the all-wing and jet-propelled Horten H IX. The Hortens test flew an unpowered glider, the prototype H.IX V1 in March of 1944. The aircraft did not look like any existing plane in use during World War II. It looked very similar to the modern American B-2 Bomber. Goering was impressed with the design and transferred it away from the Hortens to the German aerospace company Gothaer Waggonfabrik. At Gothaer the design went through several major improvements. The result was a jet powered prototype, the H.IX V2, which was first flown on February 2nd, 1945. Removed from the project, the Horten Brothers were working on the Horten H.XVIII, also called the Amerika Bomber. The Horten H.XVIII was an attempt to fulfill the German desire to build a bomber that could reach the United States. After several more test flights, the Ho 229 was added to the German JägerNotprogramm, or Emergency Fighter Program on March 12, 1945. Work on the next prototype version of the plane, the H.IX V3, ended when the American 3rd Army’s VII Corps on April 14, 1945 reached the Gotha plant in Friederichsroda. In 2008, Northrop-Grumman using available design plans built a full-size reproduction of the H.IX V3 using materials available in Germany in 1945. They also studied the only surviving parts of a Ho 229 V3, which were housed at the Smithsonian National Air and Space Museum's Paul E. Garber Restoration and Storage Facility just outside of Washington DC in Suitland, Maryland. Engineers at Northrop wanted to find out if the German craft could actually be radar resistant. Northrop tested the non-flying reproduction at its classified radar testing facility in Tejon, California. During the testing the frequencies used by British radar facilities at the end of the war were directed at the reproduction. Tom Dobrenz, a Northrop Grumman stealth expert said about the H.IX, "This design gave them just about a 20 percent reduction in radar range detection over a conventional fighter of the day." When combined with the speed of the H.IX, after detection by British homeland defense radar, the Royal Air Force would have had 8 minutes from

the time of spotting the aircraft before it reached England, instead of the usual 19 minutes. While the design was proven to be stealthy, it has been argued that it was not designed to stealthy. There is no documented evidence in Germany that the design was intended to be what would later be called stealth. In an article written by Reimar Horten published in the May 1950 edition of the Argentine aerospace magazine Revista Nacional de Aeronautica, Reimar wrote, "...with the advent of radar, wood constructions already considered antique, turned into something modern again. As reflection of electric waves on metallic surfaces is good, such will be the image on the radar screen; on the contrary, on wood surfaces, that reflection is little, these resulting barely visible on the radar." In the late 1970s and early 1980s, information began to leak to the media that the United States was working on aircraft with stealth technology. In 1983, Reimar Horten wrote in Nurflugel: Die Geschichte der HortenFlugzeuge 1933-1960 (Herbert Weishaupt, 1983) that he had planned to combine a mixture of sawdust, charcoal, and glue between the layers of wood that formed large areas of the exterior surface of the H IX wing to shield, he said, the "whole airplane" from radar, because "the charcoal should absorb the electrical waves. Under this shield, then also the tubular steel [airframe] and the engines [would be] "invisible" [to radar]" (p. 136, author translation). By 1983, the basic elements of American stealth technology were already public knowledge.

DOCUMENTS HORTEN TAILLESS AIRCRAFT – CADO INTELLIGENCE DEPARTMENT

A 26 page report created in 1945 during World War II by the Intelligence Department of the Air Materiel Command titled, “Technical Report No. 76-45 on Horten Tailless Aircraft.” This report focuses on the H.X V2 and the H.VIII. The report contains information about other Horten aircraft dating back to 1931. The information in this report was collected by the U.S. Naval Technical Mission Europe from captured documents and partly from an informant who was a draftsman for the Horten Brothers. The informant is reported to have been in continuous close contact with the Horten Brothers, until the time of his capture.

THE HORTON TAILLESS AIRCRAFT RAE REPORT This 75 page, October 1945 report was produced by the British aircraft authority, Royal Aircraft Establishment, Farnborough. It was produced from information gained in March 1945, soon after American troops took control of Bonn, by a Combined Intelligence Objectives SubCommittee team visiting the original home of Horten Aircraft. Also from an interrogation in England of the Hortens performed by a party from RAE. This was followed by a RAE team visiting sites in Germany where Horten designed aircraft were assembled. They were tasked with returning to England any remaining aircraft. Finally, a RAE team returned to Germany to interview the brothers and others in the field of German aviation.

TARGET REPORT - JAPANESE ANTI-RADAR COVERINGS Also included in this collection is the 12 page Naval Technical Mission to Japan intelligence report "Target Report - Japanese Anti-Radar Coverings." The report shows that Japan was more on track in developing what would be called stealth technology. From the reports introduction:

"Japanese research in the field of anti-radar coverings was quite intense, and while several research products proved to be rather successful, according to the data presented, it was difficult to use, in practice. Such information as was available is included in this report, and was obtained from the Air Technical Intelligence Group, which initiated the request for interrogations, data and samples." Japanese researchers were working on specifically creating a process to reduce radar detection. Their approach was to research rubber coverings containing carbon powders and anti-radar paint. The research ended with the end of World War II. Much of the documentation from the experiments was ordered destroyed by Japanese officials on August 15, 1945.

HORTEN TAILLESS AIRCRAFT CENTRAL AIR DOCUMENTS OFFICE INTELLIGENCE DEPARTMENT AIR MATERIAL COMMAND TECHNICAL REPORT NO. 76-45 ON HORTEN TAILLESS AIRCRAFT (1945)

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A det-ihod description is given of the H-IX-V2 jet propeUed tailless fighter. The aircraft is powered by two 1EMWV turbojet engines. It is equipped with five fuel tanks in each wing. Two bombs of 2200 lb each ind, four 37 mm cannons are carried. The main landing gear retracts inboard. The nose wheel is seo f -centering but not steerable. Brakes are supplied for main wheels only. No armor, leakproof tankE, and de-icing equipment are provided for this experimental model. At 20,000 ft, with full load, th, the a trp.ane is supposed to obtain a maximum speed of 720 mph. A short description is also given of th B R-VIII, a six-engine flying wing, with a maximum range of 4500 miles at a cuuising speed of 200 1aph at an altitude of 5000 ft. This aircraft will carry about 60 passengers. A list is appended of ol .ier Borten-developed aircraft, mostly gliders.

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TECHNICAL REPORT NO. 76-45

ON. HORTEN TAILLESS AIRCRAFT

A short description of a tailless jet propelled fighter built and

designed by Horten Bros. Some data is also presented on a large transport flying wing now under construction and other Horten e.aircraft.

U. S. NAVAL TECHNICALT MISSION IN EUROPE

Foreign Equip. Branch Tech. Data -,ab.: Eng. Div.

----

-

1.

Introduction.

2.

The H-1X-V2 Jet-Propelled Tailless Fighter. 2.1 2.2

General Description

2.3 2.4 2.5

Performance Controls Structure

3.

The H-VIlI

six-engine flying wing.

4.

Other Horten Airplanes. 4.1 4.2 4.3 4.4

Horten Horten Horten Horten 4.5 Horten 4.6 Horten 4 Horten 4.8 Horten 4.9 Horten 4.10 Horten 41.11 Horten 4.12 Horten

I II TII IV IV b V VI (ELM 253) VII (RIM 226) X XI XII Parabola

5.

List of captured documents related to Horten airplanes.

6.

List of figures.

Foreign Lquip. Branch Tech. Data Lab.. Eng. Div.

1. Introduction. The information presented in this report was collected partly from captured documents and partly from an informant who was a draftsman for the Horten firm.

Because of the technical limitations of the informant, some of the data must be accepted with appropriate reserve. The informant, however, had kept in continuous close touch with the designers, the Horten Brothers, until the time of his capture. Most of the data obtained pertains to a new jet-propelled tailless fighter, the H-IX-V2, which was designed and built at Goingen under the technical supervision of Major Walter Horten and Oberleutnant Riemar Horten of the Luftwaffe. In the following sections are given a short descrip.•ion of the H-VIII, a large commercial flying wing which is under construction at Gottingen, and a description of other Horten designs. The last section is a complete list of captured documents which are being processed and filed by C.I.O.S. 2.

5he H-IX-Y2 Jet-Provelled Tailless Fighter.

2.1 JZa~ This single seater fighter-bomber was designed by the Horten Bros. and built at the Luftwaffe Sonderkommando 9 at Oottingen during the War. It is the product of fourteen years of experience in tailless aircraft design. In aspect and construction it is very similar to the H-V (see section 4.6), which was built primarily for the purpose of carrying out preliminary research and development on aircraft of the H-IX type. The outstanding new feature in the H-IX-V2 is the use of jet propulsion. The first experimental design of the H-IX was designated the H-IX-ViL (V - Versuch). An increase in size of the jet-power units forced a redesign which is designated the H-IX-V._. The H-IX-Vl and H-IX-V2 are essentially similar. They are both being tested at Oranienburg. The H-IX-V3 is a version of the H-IX-V2 designed at Gothaer-Waggon Fabrik for the study of mass production problems. The H-IX-V4 is a two seater version of the H-IX-V2 intended for night fighting. It has a larger pointed nose.

2 .2 De~ipl No exact drawings of the airplane could be obtained. Three views of a project design closely resembling the H-TX-V2 are shown in figure I. Major differences between this drawing and the H-IX-V2 are indicated in the sketch of figure 2 drawn from a verbal description of these differences by a draftsman familiar with the aircraft. In

the H-IX-V2:

a.

The rear gunner is eliminated and the canopy is faired aft.

b.

In plan form the tail end of the cockpit protrudes aft of the wing and fairs to a point.

c.

The engines are further apart and moved forward.

d.

The main landing gear retracts inboard instead of outboard.

e.

There is one nose wheel instead of two.

f.

There are three movable surfaces on each wing Instead of two.

General characterlsaLcs of the H-IX-V? are as follo%,s: Span - 53.5 f'(16 meters) W:ing area - 1452 sq. ft. (42 sq. meters) Gross welght - 13,CC)C' ]bs. at full load. Foreign Equij,. Branch Tech. Data .ab.. E". - D'

Two BMW jet engines (see figures 3 to 9) Probably.BMW 003? Five fuel tanks in each wing (see figures 2 and 16) Two bombs of 2200 lbs. each. Four 37 mm cannons. Main landing gear retracts inboard. Nose wheel self-centering but not steerable. Brakes on main wheels only. Spring operated catapult seat. Armor, leakproof tanks and de-icing equipment are not provided on the experimental model. Figures 3 to 9 are photographs showing the center section of the wing of the H-IX-V2 under construction and the jet engines. Wooden assembly templates may be seen.

2.3

Urgoriao

The wing loading is 40 lbs./sq. ft. The maximum speed with full load at 20,000 ft. was quoted to be 720 mph, the landing speed 90 mph, and the endurance 4j hours. The airplane is being flight-tested at Berlin-Oranienburg. Take-off runs of 1600 ft. were obtained on initial flights with light load. It was estimated by the Germans that a take off run of 3000 ft. would be needed with full load. No wind tunnel tests were carried out for this airplane since considerable information was available from the performance of a similar airplane, the H-V, previously flown. The maximum speed of the jet-propelled Me 262 was •quoted by the informant as 560 mph and that of the jet-propelled Arado 234 as 500 mph.

2.4

Cotgl

The movable surfaces marked 2 and 3 in the sketch (figure 2), act essentially as a combination of ailerons and elevator (elevens). The inboard movable surface marked "'" in the sketch and a similar area across the center section of the wing are used as landing flaps. Maximum deflection of the control surfaces is shown in figure 10 for three positions of the stick. The indicated deflection angles are approximate. Positive angles correspond to downward deflection on the outboard aileron which has full Friese nose. The amount of protrusion below the wing contour, in the case of an upward deflection, increases from the tip inboard allegedly to avoid snatch. On the middle control surface (marked 2), the nose is a blunt Friese. Tabs are only fitted to the middle control surfaces. They act as geared balance and trim tabs. All control surfaces are statically balanced. The lever arm of the stick may be varied. By lifting the stick it assumes a position giving reduced stick forces at high speed. The kinematic principle of the control gear is illustrated in figure 11. The details of this figure actually correspond to the H-V, but the principle used is allegedly the same in the H-IX. An ingenious mechanism is used to transfer the motion of the control arm in the horizontal plane of the wing into a vertical control surface deflecting. This mechanism is shown in figures 12 and 13. Directional control is obtained by means of wing tip spoilers indicated at locations 4 and 5 in figure 2. There is one pair of small spoilers and one pair of larger spollers on each wing. The foot control gear is designed in such a way that the small spoilers protrude first, affording a more gentle action at high speed. The design of these spoilers is shown in figure 14. On most previous Horten designs, including the H-V, leading edge spoilers were used. These spoilers were hinged at the leading edge as shown in figures 11 and 15. This type of design was abandomed because of the aerodynamic shadow effect on the ailerons, high control forces, and mechanical complications. The spoilers of the H-IX slide in and out of the wing in a plane perpendicular to the direction of flight. 2.5

5

The wing is entirely of wooden construction except for the tips, which are of light metal, and the center portion which is of welded steel tubes. A cross Foreign Equip. Branch Tech. Data Lab., Eng. Div. -4-

"W.-

w.

-_

-

section of the wing is shown in figure 16. Wood glues are Kauritleim W and WHK made by I. 0. Farben. There is one main spar and one auxiliary spar. Control rods are contained inside the main box spar. The wing surface is plywood covered with special lacquer finish for smoothness. The airfoil section is not laminar. The jet engines are mounted through the main spar. Aft of the engine exhaust the wing is covered by a protective metal plate at a distance of about 10 mm along the wing surface. Extensive use has been made of wood because of a shortage of light metals and also in order to facilitate the construction. Figure 17 shows the structure of the H-V which resembles closely that of the H-Il. 3.

-TheH-VIII SiZ Fngijne Flying Win

This airplane is under construction at the Luftwaffe Sonderkommando 9 at Gottingen. It should be ready for flight testing around November, 1945. It has a span of 157 ft. (48 meters), and is powered by six 600 hp BMW pusher engines. Figure 18 Is a general view drawn by the informant from memory. The airplane range is computed to be 4500 miles at a cruising speed of 200 mph and at an altitude of 5,000 ft. It will carry about 60 passengers. The center section is of welded steel tubes. The outer wings are of wood with one main spar and one auxiliary spar. The control system is the same as for other Horten designs. Powered controls are envisaged. The nose wheel is not steerable but self-centering by spring and cam. There is no pressure cabin. The adaptation of a venturi of 3 meters diameter under the wing for use as a flying wind tunnel has been proposed. 4. 4.1

Hotn

Other Horten Airolanes" -

Glider built in Bonn,

4.2

1931-32.

(See figure 19)

Span - 41 ft. Wing area - 226 sq. ft. Weight empty - 264 lbs.

Flying weight - 440 lbs. Gliding angle - 1/21

Won Rhon glider contest.

Destroyed purposely by fire.

Sinking speed

-

2.8 ft./sec.

Hor ten. H-, Both glider and powered version - (see figures 19 and 20) 1933-34. Built in Bonn, Span - 54 ft. Flying weight - 830 lbs. wing area - 344 sq. ft. Weight empty - 605 lbs.

Gliding angle - 1/24 Sinking speed - 2.6 ft./sec.

Has good flying qualities and does not spin. the stalling speed. 4.3

The nose drops near

Horten H-III Glider built in Tempelhof (Berlin) 1938 - (see figure 19) Flying weight - 750 lbs.

Span - 66 ft. ding Area - 403 sq. ft. Weight empty - 550 lbs.

4.4

Gliding angle - 1/28 Sinking speed - 2.1 ft./sec.

Horten H-IV (RrLM 251) Glider built in Konigsberg-N Span - 66 ft. Wing area - 203 sq. ft. Weight empty - 530 lbs.

? in 1941 (see figure 19) Flying weight - 750 lbs. Gliding angle - 1/37 Sinking speed - 1.8 ft./sec.

"-5-

d0 V=,%0al5' 8 so

Outer wing panel was of metal construction because it was too thin to be made out of wood. The pilot lies in a semi-prone position.

4.5

Horten U-IVbM Glider built at Hersfeld. It was a plastic wing version of the H-IV. The leading edge was made of Tronal (plastic manufactured. by Dynamit A. 0. - Troisdorf). The flight characteristics were not satisfactory due to the stalling properties of the laminar wing. One glider crashed in a spin killing the pilot.

4.6

a Built in Ostheim 1936-38. Powered by two Hirth HM 60R (2x80 HP) engines. (see figures 19 and 21) Also built at the Peschke factory in Minden 1941-42 and flight tested in Gottingen in 1943. There have been side by side and single cockpit versions. A plastic version with flush cockpit was also built. This airplane crashed on the first flight due to a piloting error. The wings of this airplane were entirely plastic including the spars. (More details will be given in the C.I.O.S. report). Characteristics of this airplane are as follows: Span - 53.3 ft. Flying weight - 2750 lbs. Wing Area - 452 sq. ft. Power 2 x O0HP Weight empty - 2310 lbs. Max.Speed - 150 mph Landing Speed - 47 mph. This airplane was built for the purpose of carrying on preliminary research for the Horten I?- fighter.

4.7

Hort enV3I 11.[fM 253) Glider version of H-IV with a larger span and less dihedral was built at Hegidienberg and flown. Design was abandoned because the wings were too flexible for practical handling on the ground.

4.8

Horten YII -(RLM 226) Basically similar to the H-V. Powered by two Argus AS10-C (240 HP) engines. One airplane has been built at the Peschke factory at Minden and is being tested at Oranienburg. A second one is about to be completed. There are twenty on order. A characteristic feature is the use of a , bar glidin$ spanwise and pretruding from the wing tip as a directional control. (figure 22). This device has been very satisfactory in flight.

4.9

& A version of the H-III with movable wing tips for lateral control. Not very successful.

4.10 Horten H-XI Acrobatic single seat glider of about 26 ft. Hersfeld.

span being built at

4.11 Hgr ten &-XI 1 Two seater side by side with Dh'4 50 HP engine. Des'gred at Gottingen under construction at Kirt-orf. Basically s-.milar t-o H-I.1. Designed for private flying,

"-6-

4.12 Horten ParabolaCfiuei19 Glider with parabolic plan form. Destroyed by fire.

Built at Hegidlenberg.

5.

List of Cap)tured Docuents Related to

No.

1. Fluozeug- Typenbuch 1940 "2. i 1941i 3. Report on Flight tests of Horten II 4. Folder on the use of plastics 5. Design requirements for Salplanes - 1930 Vol. 6. " " "if - 1939 Vol. on kinomatics of control systems Photograph of H-2, H1-3 and H-4 9.

"

10.

i"

13. 12. 13. 14. 15. 16.

17. 18.

or~ten Airp aes.

1

III(two copies)

S

" H-2 - (four copies)

H-2 " H-2 H-3 H" 1-4 - brake flaps (spoilers) H-4 - Aileron "-" 1-k- in flight, flaps out i.arge photographs of H-2 in flight - (two photos) " H-4 in flight - (four photos) Photograph of H-4 on ground

19.

20.

Never flown.

H"'4

in

flight

22. 23. 24. 25. 26. 2ý.

H-5 on ground " H-7 in flight H7 wing under construction H-" Photographs of H-9 - installation of jet engine (seven photos) Tracing of H-1, 2, 3, 4 and 7 - plan forms Drawing of H-1, 2, 3, 4, 5 and parabola - plan forms Tracing of H-2 general arraneement Drawing of H-2L. - date 3.9 36

28. 29. 30. 31.

Drawing Drawing Drawing Drawing

32.

Drawing of H-3D - control systems No.

108-250-410-date 12/9/40

33.

Drawing of H-3B -

108-250 -

34. 35.

Tracing of H ? G.A. Drawing of H-? Elevon nose shapes No.

36.

Drawing of H-4B

37. 38. 39. 40 41.

Drawing Drawing Drawing Drawing Drawing

42.

Drawing of H-5d G. A. No.

43.

44. 45. 46.

Traaing Tracing Tracing Drawing

47. 48.

Drawing of H--6 Wooden spýar II I~o. 103-253-t~l-S /4 -date Tracing of H-6 4ooden spar 1 No. 108-253-35- - date 9/!8/42

21.

"

of ? - General Arrangements of H3B - G. A. No. 108-250 8.1 - date 7/7/39 of H-3D - G. A. No. 108-250 S.1 - date 11/18/40 of H-3D - G. A. - date 5/21/44

of of of of of

of of of of

"

"

No.

operating

?

H1-5C Model H-5C Model H-5C Model H-5 G.A. H-5d G. A. No. 8-252-0-S.I. 8-252-0-S.l.

-

41 s.4. date 6/22/39

108-251-60 - date 12/17/43 108-251-60 -date 12/8/43 -date 10/18/41 -date 10/4/41 -date 10/3/41 -date 5/30/41 (two seat) - date 3/19/42e (side seat) - date 3/23/42

H-6A G. A. No. 103-253-00 - date 5/16/44 H-6 Wing G. A. No. 108-253-51-S.1. - date 1/16/43 F-6A outer wing No. 108-253-60 - date 9/22/43 H-6V Steel spar No. 108-253-S.1-S.2. - date 9/25/42

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nr7po

49. Drawing of H-6A Outboard Elevon No. 108-253-35 " date 9/20/43 50. Tracing of H-6 Ribs 14.5, 15 and 15.5 No. 108-253-50 S17 -

date 12/8/42

51. Tracing of H-6 Ribs 2.25 and 2.5 No.

108-253-50-8.2. - date 10/12/42 52. Drawing of H-7 Spoilers Top inner No. 8-226-37-02 date 1/9/44 53. Drawing of H-7 Spoilers-left No. 8-226-37-8.1 - date 1/6/44

54. Drawing of H-7 Spoilers-lower No. 8-226-37-01 - date 1/7/43 55. Drawing of H-7 Spoilers-Top Outer No. 8-226-37-03 56. Drawing of H-7 Spoilers Surface No.

No. 8-226-37-03-01 - date 1/11/44

57. Drawing of H-7 Spoiler Details 58. Drawing of H-7 "

59. Drawing of H-7

- date 1/10/44 8-226-037-01-01 - date 1/8/44

"

60. Drawing of H-7 Spoilers Operating rods No. 8-226-37-00 - date 1/14/44 61. Drawing of H-7 Spoilers Operating rods details No. 8-226-37 - date 1/14/44 - date 3/26/42 62. Drawing of H-9 Project G.. A. 63. Sketch of H-8 (six engine flying wing) - date 12/ /40 64. Tracing of Horten Tug G. A.

65. Drawing of Horten Tug 0. A. 66. Proposals for development of the Horten Tug - date 12/15/40 67 Drawing of retractable cable system for Glider towing

6 . Tracing of proposals for highly loaded motor Sailplane - date 1/28/39 69. Drawing of H-3D control system No. 108-250-40-s.I. -

dated

/22/42

(two copies) 70. Drawing of H-5 71. Drawing of Performance Data 11-5 (six copies) 72. Photograph of Horten Parabola

73. Photograph of H1-2, 3, 4, and 5

Twelve different photographs of H-5 Photographs of H-4 - (six different photos, Three photographs of H-3 spoiler Photographs of H-6 wing under construction Photograph of H-3 wing. 9.Photograph of H1-2 . Two photographs of highly swept back model 81. Pilots control 74. 75. 76. 77. 78.

82. 83. 84.

some duplicated)

Photofraph of accident - H-3 " H-3 aileron " H-3 spoiler

H-5 " 85. 86. Drawing of H--3 controls No. 108-250-410 87. Drawing of H-3 spoiler No. 108-250-sl-U-03 These documents have been forwarded to C.I.O.S. Secreteriat in London. 6.

List of Figures Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig.

1. Preliminary project drawing of jet propelled fighter. 2. Plan view of H-IX-V2 wing. Photographs of center section of H-IX-V2. 3 to 9. 10. Deflection of control surfaces for various st!cl-* posi tions. 11. Schematic view of contrcls. 12 and 13. Aileron actuating arm linkage. 14. Photograph of spoiler. 15. Sketch of leading edge spoiler used on early designs. 1o. Crcss section of wing structure of H-TX-V2. -8-

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Photograph of wing structure of H-V. General view of H-VIII drawn from memory. View of H-1, H-il, H-11, H-IV, H-V aircraft. Photograph of H-Il. Photograph of H-V. Sketch of the protruding bar type spoiler used for directional control of H-VII.

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::':;.:>: ..' .. ::The.~.~~~iv:i.:ti~~~of·· t'he Horten. 'broth ers in. th~ .:desien. ofto.illes~ .; .... ;airc~aft... Mv~been)r:·e:ported at vtu-io us; .~imes in the. Gerinan journr u. '. . ... "Flug~por1;;" ~d .. trD.Il Slatio ns -have been. 'publi shed bYR.T.~.;during 'the : .~ . wa:;: '.The ir l'hore ~erious. effor ts be:sed on early eXper "':; , 'were not 'w~ll ~ownuntil 0. e.I.O .S. terun invest:ig~te ience' with E!l~i"., d th6ij orten home 1 .... a t:Bonn ' (iYiarch...'1945 / . ,und interv iewed Herr Berge r 'Who . suppl ied infOIlD ation ! ' o f mapy. of th~il: later ~projects.;) . • J .' " t

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" ',;' . ;.' -Afte r of :the were . inte:rroga~ed in Engla nd ({;iay 194,) and in the first two \ve~~' of June 1945· the \1rite r·. vis·n ed Genna ny, with the Horto ns,:· aYl;d inves tigate d their centr es of nctiv ity. Final interr ognti on uns c~ie d out by eo teams pqnso re9, ..by the Taill ess ,Advis'ory Oomm ittee·i n Septe mber. The mat~ria1 from these inves ·tig2. tions has been colln ted and fairl y :,' cbmple-i'e, p~.cture' of the Horte n . develo pment is pres.e n. ted : iil the follov dng ,·repo rt·., ..Theco llT.fll ete serie s of hir.cr Dft . 'is d~sq.rJ,:t>qd· cin some detai l and the' desig n metho ds used ore swnm arisoo . Re.sul.;-:t.s.cfr om fligM ;' tests on perfor mance and handl ine nre' given whore posl:!ibie~but no urittc n evide nce in ''thew ay .of repor ts or calcu lation s were ,found J>yri. ny of: the inves t,igat ors.· This featu re i,s uni'or tunatc since" ~ of the figur es ~ quoted . for perforlIlD.IlCe etc. _are' depen dent; on the accur acy of Reima r : Horte n' s memor-,f ~ . .'

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. and REd.,i uu:)io rten commenced.' ·'thei r experi nien,t s. on. taille ss aircrc .ft it the ages' of.'-ll and lO respe ctivel Y.I?Y build ing anQ.' flyin a 5!llD.ll modele:. In 1927-"they starte d glidin g rola:' in"·th e ,follow.·~ years helye d the Bonn group at' thcW asserk uppo. By 1932 \Wril t'erhD .d 'his C . glide r licenc e' and. E1i . .A2 power licenc e,:'Q. nd Reima r he.d his C gl,We r licenc~ and had start ed p,?YICr fl~ing ~"'-'

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j In 193.3 they stc.rtE :d work: on theu.- first ~ carrY~ ;~iQ.er 'which they built in the faDlil y hoIDe nt Bonn. ~Ti..'tls'be g~· with bungy \ ..:,:-, cn:tap ult launc hes'o n levol groun d; . aut'6:'i.u1d fiinch l2.unc hes wore tried . I " with:n.itmuch succe ss and final ly 'it was aero towcd .Abou t,iiwO hours -j . flyiug were di.>ncup to 11r.rc h·i934 ct1(l ·lr..ter thc.;'G it won a prize I at theRh 5n glidin £': COI'lp~ti tions as 'an origm ,n1 do·sig n. -Long itud:in al l stabi lity ~eEmS to have been fairl y good butl6 .tora lcont r61 wus urJ.ia tisfac tory (due lIlc:in ly appar ently to advGr se y~w.in g mo.ments i'rom thci( ailero ns), end longit Ud.iri a.l contr ol boorunc very: :ine:er~.

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. '·'IIIo Type (a.).but with afixOd 1'ront plMe. Orie'~f these _s.b~t. . . ' . , ;,for the ,1938 lilian contest. 'Very little nyingex.t>orlenoe W'aJI . . obtaino~. Theidoa was to improve Ci:Jna.x.;.:";'. ,". ,.

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IIIo H III glider with waggle tips~ .' Tho scheme is skot~h~d :inFig~26. On this aircraft,' remains of ,yhioh 'were ,foWldat Go~1;:ingen,.· ~o . tips were operated directly .by the pUot_ ....- ,... . , .

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IIIf' Same as I:IJ.'))·~~t.·w.th prone p6~ition' for thkp:i.lp~. A spec:imen of this type was I'oWnd by the writer at Gut Tiorsieiii' With modifiod ... cont,rol:-s_:- 'l'h,e outer. f:J.ap had a Frise. noae, (as on BIV), spoU(Jr tYPo dia:grUdflorf? wero;":f'ittod: in place. 0.'£ the usw:U. leading edge flaps" and H IV type ai.ve brakes. insta;llod. ," .. split ,',. , : . .',

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