Foro Militar General

ivasam escribió:..............Horten Ho-IX
a) Ala voladora muy rapida pero con escaso poder de maniobra
b) Util para reconocimiento pero no como arma ofensiva.
c) Posible inestabilidad en el aire, ya que en la actualidad las alas voladoras necesitan de computadoras para corregir estas deviaciones. ...........

japa escribió:Y además hay un factor que nunca ha dejado de sorprenderme: todas estas armas milagrosas, al igual que los submarinos XXI, se pensaron para intentar frenar a los aliados occidentales entre 1944 y 1945, cuando la principal amenaza para Alemania era el ejército soviético ¿Alguien conoce algún arma secreta nazi que fuera usada en el frente oriental? ¿De qué iba a servir bombardear Londres para frenar a las fuerzas de Rokossovsky en el Vístula?

miguel2 escribió:

ivasam escribió:..............Horten Ho-IX
a) Ala voladora muy rapida pero con escaso poder de maniobra
b) Util para reconocimiento pero no como arma ofensiva.
c) Posible inestabilidad en el aire, ya que en la actualidad las alas voladoras necesitan de computadoras para corregir estas deviaciones. ...........

Llegaron a volar las Horten Ho-IX? alguien sabe de alguna foto de ellas? y volando?

Saludos.

ivasam escribió:.............
Hola, por increible que paresca este aparato volo duarante dos horas aproximadamente, pero se estrello a causa de un incendio en el motor, sin embargo fue elegido para ser producido en serie, cuando los aliados se apoderaron de la fabrica solo habia uno terminado.

Respecto a la existencia de fotos de esta maravilla volando existen muy pocas.

Saludos
Iván

General

The H IX was a single seat fighter bomber of 16 m span with twin jet engines, being a further development of the H V and H VII designs. Fig. 19 is a general arrangement drawing made from a wooden model found at Gottingen, where the first two of the type were built.
Four aircraft of the H IX type were started, designated V.1 to V.4. V.1 was the prototype, designed as a single seater with twin B.M.W. 003 jets, which were not ready when the airframe was finished. It was accordingly completed as a glider (Fig. 20) (not reproducible) and extensively test flown. D.V.L. instrumented it for special directional damping tests to determine its suitability as a gun platform. V.2 was completed (also at Gottingen) with two Juno 004 units and did 2-hours flying before crashing during a single engine landing. The pilot (Ziller) apparently landed short after misjudging his approach. V.3 was being built by Gotha at Friedrichsrodal as a prototype of the series production version. V.4 did not get beyond the project stage but was to be a two-seater night fighter with an extended nose to house the extra man (Fig. 19) (missing).
In shape, the H IX was a pure wing with increased chord at the center to give sufficient thickness to house the pilot and the jet units, which were placed close together on either side.

Aerodynamic Design

The H IX started as a private venture and the Hortens were very anxious to avoid failure so they avoided aerodynamic experiments wherever possible. A lower sweepback was used than on the H V and H VII and laminar flow wing sections were avoided as a potential source of trouble. Wing section at the junction with the center sections was 14% thick with maximum thickness at 30% and 1.8% zero Cmo camber line. At the centerline thickness was increased locally to 16% to house the crew. The tip section was symmetrical and 8% thick. Horten also believed that since the compressibility cosine correction to drag was based on the sweepback of the maximum thickness line, the ordinary section would show little disadvantage.
Wing twist was fixed by consideration of the critical Mach number of the underside of the tip section at top speed. This gave a maximum washout of 1.8°. Having fixed this, the CG was located to give trim at CL = 0.3 with elevons neutral. In deciding twist for high speed aircraft, CD values were considered in relation to local CL at operational top speed and altitude (10 km in the case of the H IX). Twist was arranged to give minimum overall drag consistent with trim requirements. The wing planform was designed to give a stall commencing at 0.3 to 0.4 of the semi-span.

Structure

Wing structure comprised a main spar and one auxiliary spar or wooden construction with ply covering. The center section was built up from welded steel tube. Wing tips were all metal. The undercarriage was completely retractable and of tricycle type the front wheel folding backwards and the main wheels inwards. The nose wheel was castering and centered with a roller cam. When resting on the ground, wing incidence was 7° and the nose wheel took about 40% of the total weight.

Engine Installation

The jet engines were installed at -2° to the root chord and exhausted on the upper surface of the wing at 70% back from the nose (Fig. 22a & 22b). To protect the wings the surface was covered with metal plates aft of the jet pipe and cold air bled from the lower surface of the wing by a forward facing duct and introduced between the jet and the wing surface. The installation angle was such that in high speed flight the jest were parallel to the direction of flight.

Control System

Lateral and longitudinal control was by single stage elevon control flap with 25% Frise nose and compensating geared tap balance. (This system was also used on the H VII, see para. 4.6.) The pilots control column was fitted with a variable hinge point gadget, and by shifting the whole stick up about 2” the mechanical advantage could be doubled on the elevons for high-speed flight.
Directional control was by drag rudders. These were in two sections, slight movements of the rudder bar opening the small (outboard) section and giving sufficient control for high speed. At low speeds when courser control was necessary the large movement also opened the second spoiler, which started moving when the small one was fully open. By pressing both feet at once, both sets of spoilers could be operated simultaneously; this was stated to be a good method of steadying the aircraft on a target when aiming guns. The Hortens stated that the spoilers caused no buffeting and claimed an operating force of 1 kg for full rudder, with very little variation in speed. The operating mechanism is illustrated in Fig. 28. A change was made from the original H VII parallel link system to improve the control force characteristics. With the new system, aerodynamic forces could be closely balanced by correct venting of the spoiler web, leading the main control load to be supplied by a spring. The cover plate of the spoilers was spring loaded (Fig. 27) to form an effective seal with the rudders closed; this device was used on most Horten spoiler and dive brake designs.
On further models of the H IX it was proposed to fit the “trafficator” type rudder tried experimentally on the H VII.
Landing flaps consisted of plain trailing edge flaps (in four sections) on the wings, with a 3% chord lower surface spoiler running right across the center section, which functioned as a glide path control. The outer pair of plain flaps lowered 27° and the inner pair 30° – 35° on the glider version V.1. On V.2 mechanical trouble prevented the inner pair operating and all flying was done with the outer pair only. The center section spoiler could be used as a high speed brake and gave 1/3 g at 950 kph. No dive recovery flap was considered necessary.

Performance

Proper performance tests were not done on V.2 before its crash and top speed figures were calculated values, checked by Messerschmitts. The following figures were remembered by Reimar Horten:

Dimensions

All Up Weight, Including Ammunition and Armor 8,500 kg (18,700 lbs.)
All Up Weight, Excluding Ammunition and Armor 7,500 kg
Wing Area 52 sq.m (566 sq.ft.)
Wing Loading 33 lb./sq.ft.
Fuel (I2 Crude Oil) 2,000 kg (4,400 lbs.)

Performance at 7,500 kg (16,500 lbs.)

Takeoff Run 500 m
Takeoff Speed (10° Flap) 150 kph (95 mph)
(Note: This corresponds to a CL of 1.30 which is the stated stalling CL of the aircraft.)
Top Speed (at Sea Level) 950 kph (590 mph)
(CDo estimated to be 0.011)

Calculated ceiling was 16 km (52,000’). Engines would not work above 12 km as the burners went out.

Rate of Climb at Sea Level 22 m/sec (4,300 ft/min)
(Note: This has been checked roughly by observation.)

In tests against the Me 262 speeds of 650-700 kph (400-430 mph) were obtained on about 2/3 throttle opening. This appears to be the only flight test figure available.
Messerschmitt sent performance calculators to the Horten works to check their estimates. The method suggested by D.V.L. for getting the sweepback correction to compressibility drag was to take an area of 0.3 x the root chord squared at the center section as having no correction applied, and then apply full cosine correction over the outer wing. Sweepback angle was defined as that of the quarter chord locus. Test data was available for CDv. for zero sweepback.
The Messerschmitt method was to base sweepback on the max t/c locus and to scale Mach number by the square root cos Ø.

Stability and Control

The H IX V.1 was flown by Walter Horten, Scheidhauer and Ziller. Scheidhauer did most of the flying (30 hours) at Oranienberg, Horten and Ziller flew for about 10 hours.
D.V.L. instrumented the aircraft for drag and directional stability measurements. No drag results were obtained because of trouble with the instrument installation – apparently an incidence measuring pole was fitted which could be lowered in flight and glide path angle was obtained from the difference between attitude and incidence measurements. One day they landed without retracting the pole. Directional oscillation tests were completed successfully and an advance report was issued (10 pages of typescript) by Pinsker and Lugner fo D.V.L.
The essence of the results was that the lateral oscillation was of abnormally long period – about 8 sec. At 250 kph and damped out in about 5 cycles. At low speeds the oscillation was of “dutch roll” type but at high speed very little banking occurred. Many fierce arguments took place at D.V.L. on desirable directional stability characteristics , the Hortens naturally joining the “long period” school of thought. They claimed that the long period would enable the pilot to damp out any directional swing with rudder and keep perfectly steady for shooting. It was found that by using both drag rudders simultaneously when aiming, the aircraft could be kept very steady with high damping of any residual oscillation.
Lateral control was apparently quite good with very little adverse yaw.
Longitudinal control and stability was more like a conventional aircraft than any of the preceding Horten types and there was complete absence of the longitudinal "wiggle" usually produced by flying through gusts. Tuft tests were done to check the stall but the photographs were not good enough for much to be learned. Handling was said to be good at the stall, the aircraft sinking on an even keel. There seems to be some doubt, however, as to whether a full stall had ever taken place since full tests with varying CG and yaw had not been done. Although the stick was pulled hard back, the CG may have been too far forward to give a genuine stall.
Directional stability was said by Scheidhauer to be very good, as good as a normal aircraft. He did not discuss this statement in detail as he was obviously very hazy about what he meant by good stability and could give very little precise information about the type and period of the motion compared with normal aircraft.
Scheidhauer had flown the Me 163 as a glider and was obviously very impressed with it; he was confident enough to do rolls and loops on his first flight. We asked him how the H IX V.1 compared with the 163; he was reluctant to give an answer and said the two were not comparable because of the difference in size. He finally admitted that he preferred the 163 which was more maneuverable, and a delight to fly (he called it “spielzeug”).
The H IX V.2 with jet engines was flown only by Ziller and completed about 2 hours flying before its crash. This occurred after an engine failure – the pilot undershot, tried to stretch the glide and stalled. One wing must have dropped, for the aircraft went in sideways and Ziller was killed. Before the crash a demonstration had been given against an Me 262; Horten said the H IX proved faster and more maneuverable, with a steeper and faster climb.
In spite of the crash, Horten thought the single engine performance satisfactory and said the close spacing of the jets made single engined flying relatively simple.