by Doctor Reimar Horten
(as translated by: Fernando Walter Siarez, Buenos Aires, Argentina)
(The original article was titled "Ala volante Caza 'Horten IX' ", by Dr. Reimar Horten, published by Revista Nacional de Aeronautica, (today: Aeroespacio, Revista Nacional Aeronautica y Espacial) " May 1950, number 5, pages 19-20; Buenos Aires, Argentina. We thank them for allowing the translation and publication here for all to share. The article is being provided in both English and Spanish.)
The performances and qualities a modern fighter must have are very varied. In peacetime, the fighter development is always oriented towards its maximum speed, despite that there are many performances and qualities that determine its value during combat missions.
If the fighter is 100 Kilometers/hour [about 60-mph -Trans] faster than the bomber plane, it can overtake this latter and absolute speed is a secondary subject. During combat between fighters, higher speed is an advantage, as is higher climb rate and higher ceiling. Turning radius or time for a complete turn, are other performances that are not less important, to mention some of them.
To avoid combat, maximum speed is the only decisive one, but this is not the mission of a fighter. To intercept and achieve air supremacy, it is advantageous the higher starting position. If surprise factor fails, combat transforms into a "turning" combat. To be able to fly with small diameter turns, low wing loading is needed, from which a big wing results, what is advantageous for the practical ceiling. With this wing, take off and landing speeds, mainly the latter, are kept in an easy to dominate envelope and the amount of fuel carried aboard -that in jet aircraft can never be sufficiently large- allows satisfactory range values. The big wing does not decrease largely the maximum speed in jet fighters, because that is influenced only by aerodynamic design. This phenomenon comes from the fact that at such velocities, sonic speed is frequently achieved, so getting big additional drags. So, for example, the swept wing provides a mean to delay this drag increase, to much higher speeds.
Other factors of equal importance as speed, ceiling and turning radius also determine the combat value of a fighter. To describe them all will take us too far and is out of the scope of this article. I want only to remark the visibility of the aircraft. In the past, the detector was human eye, later it was the grounded radio that provided guidance until the airplane met the enemy. Today the pilot has the assurance of recognizing, even at night, an airplane flying many kilometers far, by means of the radar. In the past, planes were covered with camouflage paintings, and with the advent of radar, the already considered antique wood constructions, turned into something modern again. As reflection of electric waves on metallic surfaces is good, such is the image on the radar screen; on the contrary, on wood surfaces, that reflection is little, these resulting barely visible on the radar.
A fighter must use the surprise factor, especially at night; to do that, the plane must be built in wood, not only for the above mentioned circumstance, but also because the wood surface resistance to impacts is not necessary inferior to that of metallic surfaces, as was shown by tests. Also, those resistances are regarded of secondary importance, because with modern big gage guns, an impact means practically a total loss.
As far as landing speed is concerned, I want to say some words, because very often it is given a secondary importance: personally, I consider it very important because "cold losses" depend on it. Any loss is a victory for enemy. So, landing speed has great importance, besides the fact that it determines service possibilities in bad weather and at night. On the other hand, a pilot that has just ended a combat cannot be asked for high skill performances, needed with high landing speeds. Another point deserving mention, is that practice demonstrated that during a war, type specialization cannot be kept: the fighter drops bombs, takes part in ground combats, makes night interception and reconnaissance flights. Technology would like to solve a specific problem; anyway, it has to design the fighter as a multi-role aircraft and accept many compromises in such a way, that it must be able to carry bombs, or supplementary droppable tanks when it flies in a defensive mission; it must also be able to launch rockets, or be provided with an automatic movie camera, etc.
Guided by these thoughts, I built in 1943 the Horten IX model, from which two prototypes were built in the own firm, passing in 1944 to series construction under the license Gotha-Waggon Gotha. It is a flying wing of 16 meters span, equipped with two Junkers 004 turbine engines, built in three parts, the central wing section and two exterior parts. The central part that bears the load is 3.2 meters [10.5 ft -Trans] long and is built in steel tubing; in it the landing gear, turbines, weapons and pilot seat are fixed.
The turbines are inside the wing and receive air from the leading edge, without deflections. The cabin is put in the vertex of the sweep angle, between both motors, and is equipped with ejector seat, so as to allow the pilot to descend in parachute, without risk, at high flying speeds; besides the necessary armor, it has radio and identification instruments. Four MK 103 cannons, 30 mm gage, of 900 m/s of initial speed that produce a noticeable effect on the target and a ballistic corresponding to flight speeds. It has a hanging device for two bombs of 1000 Kilograms each, or for two droppable supplementary tanks, also of 1000 kilograms each. Its range is of 4000 Kilometers with 2400 kilograms of fuel in the wing, but it could be extended considering the very improved fuel consumption of today.
The landing gear, with nose wheel, had been designed for the aggravated conditions of night flying and was retractable to the wing center section. In spite of the low landing speed, of 140 kilometers per hour [87 mph -Trans], a detachable drag parachute had been installed, which allowed very short landing runs. In the center section also is installed a aerodynamic brake that permits a rapid adjust of the own speed to the enemy's own one, and that can be also used for landing. The cover shells are wood "monocoque" parts, easy to dismount for maintenance of the engines [and of ] the weapons. The second model was a two place one for night flights and training. The outer wing parts, completely built in wood, are of single spar construction. The leading edge is built in shaped wood, this is, milled wood, mixed with adhesive and then pressed to the definitive shape. By means of this construction method, a high quality product of any shape and size, can be made. The spar that transmits the forces from the wing fitting to the "monocoque", houses in its interior the command push rods. All wing space must be filled with fuel, using very simple rubber bags, attached to the monocoque. The rudders, mounted as brakes at the wing tips, produce a safe effect at any speed, and -by means of some manipulations- can also serve as elevators, so as to assure, even in supersonic flight (it can happen in a down pitch) total dominion of the plane.
After five years have passed since the last construction in Germany, I can demonstrate that the Horten IX has not been surpassed by more recent constructions. Speed records are, today as yesterday, over 960 Kilometers an hour [596 mph -Trans], its maximum speed, but the general design combination has not been excelled. The fact is that the construction principles should have been guided only by the physical phenomena arising from experiments with other built airplanes, without copying them. The contrast to this is the conventionally built airplane, resulting from the average of several ones, to be built
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-Ala volante Caza "Horten IX" Por el Doctor Reimar Horten
Las performances y cualidades
que debe tener un caza moderno son muy variadas. En tiempos de paz, se
orienta siempre el desarrollo del caza hacia su velocidad maxima, a pesar
de que son muchas las performances y cualidades que determinan su
valor para el combate.