Schlüter Control Systems

 

Original Fixed Pitch Head (1972)

detail view.

Rotor head fitted to the first production model of the Cobra.  Fixed pitch teeter head without damping, fixed 'coning' angle and no flap or lead-lag facility.

Flapping Fixed Pitch Head (1973)

Kit view  Flapping 'S' head early version  Late version fitted with square blade holders.

Known as the 'S' rotor head.  An updated version of the original fixed pitch rotor head with pivoting blade holders in the vertical direction to allow the blades to 'take up' the natural coning angle depending upon the lift being generated and also to 'flap', depending upon cyclic lift variations as the blades move 'upwind' and then 'downwind'; no lead-lag facility.  Fitted to DS-22 and Gazelle. First version had the 'round' blade holders but later in 73 this was changed to the 'square' type; reason for this was that the pitch of the blades with the round holders depended upon the position when bolted down hard and this was used to balance them.  Unfortunately removing the blades upset this setting and it needing checking every time.  With the square blade holders the pitch was adjusted by 'deforming' the blade holders and thus unbolted them did not change the pitch setting when they were next refitted and so the tracking did not require constant checking.

Expert Head (1974)

The 'expert' head was Schlüter's first production rotor head with collective pitch control achieved by the raising the flybar up and down thus superimposing a collective input onto the Hiller operation of the flybar; similar principle to the rotor head design of the model 2B from Jim Morley that won the RCM&E competition with judge Dieter Schlüter, coincidence!!! .  Collective range was not particularly large but at least now an approach to landing could be made without the inevitable reduction of rotor speed and controllability that was inherent with the fixed pitch layout. No lead-lag of flapping facility but fitted with teeter damping.  Available either as standard or an upgrade for the earlier models i.e. Cobra, DS-22, Gazelle then later being supplied as the 'standard' head for the Gazelle.

Heli-Baby head (1975)

Fixed pitch 'teeter' head without damping and a simplified version of the original 1972 fixed pitch head with ball bearings fitted to the cyclic movement but brass bushes only for the teeter bearings.  With fixed coning angle and no lead-lag or flap facility.

Heli-Baby head (1976)

Uprated version of the Heli-Baby 1975 head incorporating lead-lag and the 'flat' fitting of the blade holders in order to help retain the pitch setting if the blades are removed (as per revised 'S' head above).

Super Heli-Baby head (1976)

Collective control by a rod running in a sleeve up the main mast and moving the mixer block position above the flybar linkage driver.  Linkages connected this block to both the main blades and flybar thus collective control was 'superimposed' on the flybar cyclic movement (Hiller only).  No lead-lag or flapping facility but had slight teeter movement restrained by sleeves.  The layout though lacked engineering 'finesse' as it was basically an 'add on' but it did have rotational balance.

Bell_222 head (1977)

fitted to Bell_222  fitted to Heli-Baby 

Upgraded Heli-Baby collective pitch head moving the 'mixer' block onto the flybar itself thus removing the need for two sets of long linkages giving a much tidier layout.  Operation remained the same with 'Hiller' cyclic control and no lead-lag or flap facility.

Heli-Boy heads (1978)

Updated version of the 1973 fixed pitch flapping head incorporating lead-lag hinges; used for the basic trainer version of the Heli-Boy.

Updated version of the 1977 Bell_222 head incorporating mixing levers on main blade blade control arms with linkages to both the flybar and the swashplate thus superimposing direct swashplate control onto the previous 'Hiller - collective' layout.  Generically known as a 'Bell-Hiller' collective pitch head, teeter damping but no lead-lag or flap facility.

System 80 Collective head (1979)

  

Updated version of the 1978 Bell_222 Bell-Hiller head with lead-lag facility, teeter damping but no flap facility.

Schlüter system 80 build instructions  -  German with pictures.

Schlüter system 80 build instructions  -  English without pictures.

Four Blade 'scale' head (1979)

 

Developed for the Schlüter system 80 and used four individual blade holders with lead-lag facility bolted to a twin plate hub which was solidly fixed to the main shaft without any damping.  Now this was a true 'Rigid Rotor' system.  From experience of other manufacturers, positive control would only be achieved by blades with a forward and well outward centre of gravity; a set of special blades were provided which incorporated weights that were glued into the front outer edges.  If these blades were not used the rotor head was unstable.

 

 

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