FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1951
1951 - 0598.PDF
37© FLIGHT, 30 March 1951 AIRSCREW SHAFT I TORQUEMETER SWITCH TORQUEMETER PISTONS FRONT COVER COUPLING CONSTANT TO REMOTE SPEED GEARBOX UNIT MAIN AIR INTAKE DEVELOPED MAMBA... possible as a result to relight at all conditions of engine and air-craft speeds so far encountered. Previously some relighting prob- lems had been experienced at high air speeds.Although only a cynic might be expected to recognize any association between deck landings and walking-sticks, anotherimportant modification to the Mamba's combustion chambers was, in fact, concerned with both. Colloquially, the primary airtubes in the Mamba's combustion chambers are known as walking- sticks and, following experience of Mamba or Double Mambaoperation from the decks of aircraft carriers, it was found necessary to lengthen these tubes in order to meet a requirement for extremelyrapid engine response to power-lever movements. In the same connection a system of control has been introduced which keepsthe engine speed constant over the major part of the power range, and this in turn has meant that at low power the combustionchambers have to burn a much weaker air-fuel mixture than was previously the case. The modifications have enabled the require-ments to be met without the mixture in the chamber reaching the extinction point on the weak side or, in other words, "without thefire going out." Students of the Mamba will notice several other minor modifica-tions shown in the latest cut-away drawing. It will be seen, for example, that the air-cooled centre bearing is now similar to that ofthe Adder, illustrated recently in Flight, a modification having been introduced to eliminate the complication of an extra scavengeline. The aid of the Ultra Electric Company was sought in manu-facturing a new type of micro-switch for the ignition cut-out governor and reverse-torque switch on the reduction gear. The equipment had been specially developed by Armstrong Siddeley.Another device produced by the same contractors to meet Arm- strong Siddeley requirements is the jet-pipe temperature-controlselector on the cam box. Its duty is to select a temperature to correspond with engine speed. In high ambient-temperatureconditions fuel is bled-off by means of a Lucas solenoid bleed- valve controlled by a magnetic amplifier.Among the accessories of the Mamba will be seen the latest Rotax Exp. 4112 starter, which has an increased output for themore powerful Mamba and can also provide the bigger power margin sometimes required for very cold conditions.The Mamba drives a de Havilland airscrew (both three- and four-blade varieties have been tried out), and another accessory inthe group on top of the compressor is the 711 constant-speed con- trol unit. Although a stage in the development of the Mamba has beenreached at which it is appropriate to review progress, it should not be assumed that no more improvements can be expected. Work is,in fact, continuing on the basic unit, and flight experience under a variety of conditions is being obtained as rapidly as possible.Important current installations of the Mamba are, of course, in the Apollo, experimental Mamba-Dakota, Short S.B.3 and, in doubleform, in the Fairey 17 (ordered in quantity for the Royal Navy) and Blackburn Y.B.I. Both in single and double form the Mamba's future is unques-tionably bright for commercial and military installations. With substantial Service backing, five years' experience already behindit, and a fuel consumption figure already attractive yet still improv- ing, it may well outstrip other turboprops in its class. 1
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
