DESCRIPTION. The F-55 is another of the Feuerlilie series of rocket propelled guided missiles which the LFA (Luftfahrtforschungsanstalt Hermann Göring e.V.) located at Vol-kenrode/Braunschweig, Germany was developing in order to obtain aerodynamic data in the transonic region. Although the primary purpose of the Feuerlilie series development work was to obtain aerodynamic test data, there is evidence that a certain amount of though was being given to the possibility of using the F-55 as a weapon.

The Feuerlilie F-55 has a fuselage 4.8 meters in lenght and a diameter of 55 cm. he wing span of the two main fins which are attached to the afterbody of the fuselage is 2.6 me-ters. The first F-55 had a solid propellant rocket drive, but later models used a liquid roc-ket motor with a dry powder assisted take-off unit.

The F-55 was to be ground launched and it was expected to reach an altitude of 4,800 meters with a maximum horizontal range of 7,500 meters. Elaborate plans were also being made to install telemetering and to follow the flight path of the missile by cine-theodeli-tes.

HISTORY OF DEVELOPMENT. Development work on F-55 was started about May 1944 by Dr. Gerhard Braun of LFA. The body for the F-55 was built by Ardelt Werke, Eberswal-de, Breslau.

The production scheduled for experimental models of F-55 for the year 1945 called for a total of 35 with deliveries of at least 3 per month for the first 10 months of the year. These were to be tested with various stabilizing systems and the later models were also to be equipped with telemetering and remote control equipment.

The first model of F-55 with solid propulsion was tested at Leba, Pomerania in May 1944, with satisfactory results, a Mach number of 1.25 being attained. The second model with a liquid fuel system and take-off unit was tested at Peenemünde on 11 December 1944; this model went into a spin about its pitch axis shortly after leaving the launching track. The third model had been sent out to Peenemünde for testing, but had not yet been tes-ted.

CONCLUSIONS. Since the Feuerlilie F-55 was primarily a research project, it is of inte-rest largely from the standpoint of the methods tried and the techniques of flight obser-vations used.

As the F-55 like the F-25 was a manifestation of the Volkenrode research groups' ideas, it undoubtedly represents a high order of an aerodynamic development and requires treatment as such. The Brauchschweig documents, duplicated by the United States Army Air Force and evacuated to Wright Field, Dayton, Ohio, include comprehensive re-ports on the Feuerlilie series.

DETAILS. Airframe. The airframe of the Feuerlilie F-55 consists of a fuselage 4.8 meters long, and having a maximum diameter of 55 cm. There are two sharply swept back wings having a span of 2.6 meters. Two vertical fins are mounted at the extremities of the wings, this position being chosen to keep them out of the wake of the body.

The outer halves of the training edges of the wings are movable so as to give aileron control. No rudder is provided, yaw control being obtained from aileron action.

POWER PLANT. The power plant used for the first model of F-55 was the RI 503 solid propellant type built by Rheinmetall-Borsig. For the second and third propulsion unit de-signed by Dr. Contrad of DVX (Deutsche Versuchsanstalt für Kraftfahrzeuge und Fahr-zeugmotoren) located in Berlin. In addition, an assisted take-off unit, "Pirat", a solid pro-pellant rocket was used.

Thrust

Time of burning

Weight of fuel

Impulse

CONTROL SYSTEM. On the first model of F-55, no roll stabilization was used. On the second and third models, gyro equipment developed by Fischl of DFS (Deutsche For-schungsanstalt für Segelflug) was tried. This system used a single gyro with Askania pneumatic rubber servos. It was expected that the rubber would provide the necessary mechanical damping, but due to the fact that the only test flight on which this system was used failed, it was impossible to determine whether or not this was the case. On subsequent models, it was proposed to use a Horn gyro system consisting of two gyros, one of which was used for damping only. This system was also to be used with the Askania pneumatic servo system of remote control.

In connection with the Feuerlilie programs, a new telemetering system "Stuttgart" had been developed which had 12 channels and gave 20 values per second with an accuracy of ± 5 percent. This system was designed by the Forschungsanstalt Graf Zeppelin, loca-ted in Stuttgart/Ruit.

WARHEAD AND FUZING. Since the F-55 was primarily a research missile in the early stages of its development, there was no provision made for a warhead. Like the F-25, a Rheinmetall-Borsig time fuze was used to ignite the flares mounted on the wing tips to insure satisfactory tracking of the missile in flight by means of cone-theodolites.

LAUNCHING. The F-55 was launched from an inclined ramp built by Ardelt Werke, Bres-lau. The launching angle was 20° to the vertical.