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Aviation History
1947
1947 - 0444.PDF
•270 FLIGHT MARCH 27TH, 1947 THESEUS AIR TESTING First Bristol Airscrew Turbines Fly in a Lincoln : Some Features Discussed C>S than two months ago Flight reported the successfulcompletion of a full type test by a Bristol Theseusairscrew turbine, and also mentioned that the instal- lation of two such units in a Lincoln was almost com- pleted. By making a total run of 156 hours, of which 127 were taken up with the official test schedule, the Theseus became the first airscrew turbine in the world to earn this qualifica- tion. This fact was duly inscribed on the certificate re- ceived from the M.o.S. on January 28th, and bearing the signature of the director of Engines Research and Develop- ment, Capt (E) 1VI. Luby, R.N. Another test is to be undertaken during the next few days in which the take-off rating will be increased. Some details of the installation of two Theseus power units in the outboard positions in an Avro Lincoln for flight testing are now available. It is a tribute to the keen- ness and industry of all concerned, particularly the ground engineers, that engines received in the hangar on December 24th and January 10th respectively were installed and run- ning successfully by January 24th. Brief taxying tests were completed by February 6th after numerous delays due to weather, and Mr. Pegg, chief test pilot, finally took -off from a snowbound airfield on a short first flight on February 17th. Since that time weather has permitted four or five other flights, and an initial handling schedule of about 25 hours' duration has been commenced. Preliminary reports show that the Theseus units are functioning very satisfactorily and that they are smooth arid quiet. On test on the ground the engines can be seen to be free from vibration, and the noise seems to be confined chiefly to the high-pitched whine of the turbine and a low rumbling from the airscrew. Readers may like to be reminded that the standard Avro Lincoln has a span of 120 feet, an a.u.w. of 82,000 lb, and an empty weight of a little over half that figure. Its four 1,705 h.p. Merlin 85s give it a maximum speed of over 300 m.p.h. at 18,000ft, and its ceiling, a feature of special importance in connection with Theseus flight tests, is 35,000ft. In the Civil Aviation section of this issue may be found an artist's impression of the Handley Page Hermes V in which four Theseus engines are to be fitted. Some pre- liminary details and figures for this important design are also given. This is the only installation so far announced for Theseus airscrew turbines, but several more may confidently be expected and some preliminary design studies for other possible installations have already been made. The Bristol Theseus itself was described in Flight of October 10th last year. In effect, it is two units in one, a gas generator (nine-stage axial compressor and two-stage turbine) and a separate turbine-driven airscrew. The nature of the "controller," a governing device for main- taining through automatic airscrew pitch control a constant speed ratio between the two turbines, is still confidential pending the granting of patents. Its function is most important and the fixed ratio of airscrew turbine to com- pressor turbine speed is 1.12:1. An infinitely variable gas coupling development is foreseen which might have many interesting effects on the operating conditions of the engine. Incidentally, in giving figures for engine speed the com- pressor r.p.m. are always stated. For example, the engine Details of the supporting structure,bulkhead position, and downward-inclined jet pipe with controllable orifice, areclearly revealed in this g.a. drawing of the Theseus in the Lincoln II. The weightof the power plant less airscrew is 2,687 Ib.
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