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Aviation History
1963
1963 - 1430.PDF
248 FLIGHT International, 15 August 1963 Key to both drawings 1 Payload. This is primarily an Italian responsibility 2 Payload carrier 3 Access panels 4 Eight modules of guidance, control and telemetry equipment 5 Main thrust ring 6 Tankage ring suspension 7 Explosion-formed I mm titanium alloy 8 Electron-beam seam weld 9 Aerozine 50 fuel tank 10 Nitrogen tetroxide oxidant tank 11 Welded aluminium-alloy tubular framework 12 Glass-fibre helium tank 13 Qimballed vernier motors 14 Main thrust-chamber gimbal 15 Main thrust chamber. 4,9601b thrust 16 Electro-hydraulic actuators 17 Jettisonable half-skirts 18 Pre-loaded inter-stage attachments 19 OPHOS IE liquid-hydrogen tank 20 OPHOS IE liquid-fluorine tank 21 Hydrogen fuel from (19) 22 Hydrogen filler 23 Main thrust chamber, 8,4701b thrust in vacuum From the start of their work on the third stage the German designers have been keen to use high-energy propellents, and Bolkow have prepared studies of three OPHOS (Optimierte HOchenergetische Stufen) third stages. That shown above is OPHOS IE, with pressurized hydrogen /fluorine propulsion, discussed in the concluding paragraphs on the following page Left: Although many details still remain unresolved, the broad design characteristics of the ELDO third stage have long been agreed and are illustrated here. Payload on the first orbital launch, in 1966, will be primarily a technolo gical one concerned with vehicle performance, but it may include one or two instruments to provide data for the Italian satellite designers ELDO THIRD STAGE a propulsion system of low thrust burning more or less contin uously from stage separation to the final injection into the desired orbit. Throughout the second half of 1961 the leading German aircraft manufacturers discussed their participation in the programme and conducted preliminary studies into the technical, administrative and political problems involved. On December 15 the first two proposals were received, from Ernst Heinkel Flugzeugwerke, of Speyer, and Bolkow Entwicklungen KG, of Ottobrunn bei Munich. Early the following year further proposals were received from Focke-Wulf, of Bremen-Flughafen; Hamburger Flugzeugbau, of Hamburg-Finkenwerder; and Weser Flugzeugbau, of Bremen. The five German firms continued to refine their proposals, and at the Hanover air show in April 1962 Focke-Wulf exhibited a full- scale mock-up of a typical third stage, with four thrust chambers. It bore the name Black Prinz, a curious mixing of the British code name and language with the German. Extensive parametric studies continued to evaluate stage weight, performance and estimated cost, assuming various payloads, thrusts and propulsive systems. At all times there was a strong inclination on the part of the German technicians to adopt a high- energy liquid-propellant system, and liquid-oxygen/liquid-hydrogen and liquid-fluorine/liquid-hydrogen at all times offered by far the greatest theoretical performance. These studies into high-energy stages have never ceased to occupy a high proportion of the Ger mans' thinking, and the advanced proposals of one company are discussed at the end of this article. But for the first-generation ELDO vehicle it was clear that a more conservative propellant combination would be necessary. Ultimately Germany agreed to adopt the same propellant com bination as that used by the French in the second stage. The oxidant is nitrogen tetroxide (N204), and the fuel is "Aerozine 50," a 50-50 mixture of hydrazine and UDMH. This propellant mixture has the advantages of being both hypergolic and non-cryogenic, and happens to be the same as that adopted in the USA for Titan II. Many studies were made with stages having low-thrust engines. The RAE at Farnborough favoured such an approach because the total impulse could be controlled merely by governing the total burning time, and this can usually be done with great reliability and accuracy. Eventually, however, the German designers chose to use an engine with a thrust almost as great as the aggregate weight of the stage and payload. The companies chiefly responsible for the third stage of the ELDO launch vehicle today comprise Bolkow and ERNO. The latter stands for Entwicklungsring Nord, or development centre north, a group formed by Focke-Wulf, Hamburger and Weser. These companies and their increasing number of subcontractors ah operate under the national co-ordinating authority of ASAT (Arbeitsgemeinschaft Satellitentrager—satellite carrier advisory group). ERNO's task has been to design and develop the main anu vernier engines, propellant supply system, tanks and structure. Bolkow are handling the design and development of the electronic equipment, the control and attitude reference system, system checK- out and vacuum testing and final inspection of the complete stage- Bolkow are also developing a second vernier engine, as noted later. Major design features of the vehicle are clearly shown in our artist's cutaway drawing. The two propellants are contained i
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