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Technical Data for Nimbus 4DM |
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Layout Options | Standard
Features and Options
The superseding of the Nimbus 3DM self-launching sailplane
by the Nimbus 4DM is based on two concepts. First, to again make use of
the opportunity to produce a top class two-seater with an outstanding glide
performance The movement amay from the propulsion system hitherto in use was inspired by the highly positive experiences gained from operating the Discus bM, which also has the engine "buried" inside the fuselage. That is to say that its increased climb and reduced noise values were so convincing that they could not be ignored, not even when considering the additional development work which was inevitable for the stronger engine required for a two-seater. The choice of the power plant was then made in favor of a liquid cooled 59 HP Rotax engine model "535 C" (now replaced by the SOLO engine type 2625 !), which was also used in the Janus CM and Nimbus 3DM. Its location inside the fuselage of the Nimbus 4DM, however, causes much less drag, and as only the propeller is exposed for launching, the latter is also more effective. The composite propeller, with its wide chord blades, is a development by TECHNOFLUG and W. BINDER and produces an additional gain in thrust. Compared to its predecessor, the take-off run of the Nimbus 4DM is considerably shorter and the climb is distinctly better. It is also superior to the single-seater Nimbus 4M. In particular, the rearrangement of the power plant's
position results in very substantial reduction of the operating noise.
This is achieved by the dampening effect of the walls of the engine compartment
and the shell of the fuselage. Further factors diminishing the noise of this power plant system (developed by W. BINDER) are the noise absorbing hollow propeller pylon in which the drive belt is routed, an air intake silencer, and the upward pointing outlet of the muffler. The noise emission archived by these measures is distinctly below the limits imposed by the authorities. Nevertheless the Nimbus 4DM should predominantly be flown in the sailplane configuration as it is not intended to be operated as a "touring" aircraft. Its propulsion system is principally designed for a powerful take-off and climb. The extension/retraction of the propeller pylon (with the radiator bolted to it) is by means of an electrical spindle drive. In powered flight the doors of the engine compartment, which features a heat reflecting foil coating, remain open to cool the engine and its muffler. The power plant is controlled and monitored in a well proven may by means of an ILEC multi-function control unit which, as an option, is also available for the rear seat. It continuously displays not only engine RPM and coolant liquid temperature, but also indicates incorrect procedures. For instance, the starting of the engine with the propeller arrested or the fuel valve shut off. Furthermore, this unit displays the voltage of the battery, indicates a low fuel level, and shows whether the propeller pylon is fully extended or retracted etc. In the case of a failure of the pylon control, an emergency system is provided for each Nimbus 4DM. This is also used in the single-seater Nimbus 4 and overrides the electronic boxes and a number of limit switches. In addition to the 12 V (24 Ah) power source provided to operate the power plant system, which is recharged in flight by a generator, there is of course, space for further batteries needed for gliding avionics. A ground service receptacle is installed on request. A nose towing hook is fitted as standard so that the Nimbus 4DM may also be operated with its engine removed. A belly hook can be fitted as an option. Both methods of launching (by aerotow or winch) are also approved with the engine in place and the aircraft fully loaded. The power plant system is designed such that the engine can be quickly removed or reinstalled. This is ensured by using a number of quick disconnect couplings for the electrical and fuel system and by easily accessible engine suspension points.
Technical Data and Performances for Nimbus 4DM
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and handling characteristics derived from the single-seat model. Second,
benefiting from the advantages offered by a power plant system remaining
inside the fuselage, not only in respect of noise emission (the criterion
nowadays), but also regarding the performance in powered flight.
