Fuelless Steering and Station-keeping for solar sails
- Đ Frank Ellinghaus -

I N D E X - G E R M A N

POST & AUTHOR & Vision
STS - Solar Thruster Sailor
RSS - Ring Skeleton Structure LTH - Launcher Transport Head EFO - Experimental Flying Object RSC - Rotational Slingshot Catapult
L I N K S ENGLISH

Fig.1 - Fig.2a-2b - Fig.2c - Fig.2d - Fig.3a-3b - Fig.4a-4c - Fig.5 - Fig.6 - Fig.7 - Inner Ring - Flying Ring - Fig.8 - Fig.8a - Fig.8b - Fig.9 - Fig.9a - Fig.10 - Fig.11 - Fig.10 - Fig.11 - Fig.13 - Fig.14-15 - Fig.16 Mobile Thruster Unit - Fig.17 - Fig.18 Fuelless Steering - Fig.19-21d Solar Sail Launch System

Fig. 18 - Fuelless Steering and Station-keeping for solar sails

Fig. 18 shows a solar sail with a fuelless steering and attitude control system (ACS). Unfurling and furling the sail ballast panels (here ballast panels BA, BC, BD and BE) steers the sail craft through shifting the center of mass a bit and at the same time shifting the center of light pressure into the opposite direction. In contrast to pure mass shifting ACSīs this roller furling system adds two shifting processes for enhanced steering power into one steering operation.

As the sail has a central docking station it is also possible, to enhance the mass shift through moving the payload or daughter units of the mothership with the help of moveable docking brackets. As well displacing the center of mass up towards Sun through placing the payload accordingly if the craft carries a magazine docking station is an option. With that constellation the solar sail would "drag" itīs center of mass behind it which would produce some kind of stabilization.

Further possibilities for fuelless attitude control are moveable control bars or vanes fixed to the outside of the outer ring.

This versatility shows the usefullness of a solar sail design with a stiff outer ring gossamer structure and central payload and docking station which has ample space and possibilities for spacecraft steering as well as for convenient payload mounting and docking.

Solar sail with fuelless steering and attitude control system (ACS)

The solar sails structure constists of a stiff outer ring skeleton (1) which carries low-thrust-thruster-units (1.5 and 1.6) and solar panel rolls (1.11) directly fixed to itīs pipe body.

The area inside of the outer ring is made up mainly of the sail panels. Besides the fuelless steering options it can also use itīs thruster units for steering but also as a secondary propulsion option.

Shifting and rolling Ballast sail panel segments for steering purposes.

The ballast sail panel segments (here BA, BC, BD and BE) are thought to stand often furling and unfurling on and off their sail panel rolls. As they have to be way thicker and heavier as the regular extremely thin solar sail foil, they are well suited to serve as ballast mass for steering purposes.

In this drawing the ballast steering panels BA and BD are rolled up to half of their unfurled area onto the sail panel rolls 1.11. That means the mass of the sail panels is shifted to the rolls of panels BA and BD and with it the sails center of mass - cm - as shown in the sails middle part is shifted into the same direction.

The center of solar radiation pressure force ( here shown as cf ) however is shifted into the opposite direction. As BA and BD are both rolled up halfway, in this case the sail is turned upwards via direction VR shown on the sail panel F while the pressure of the stronger radiation force (the opposite, fully unfurled panels have more sail area) pushes the sail down at the sail panel E. The longer the way between cm and cr the more steering inertia accrues per time unit.

By varying the length of the unrolled ballast panel segments it is even possible to shift the turning direction between the two segments which are actually used for steering according to their working ballast area.

Fig. 21 shows another kind of solar sail with ACS (for a more detailed description take a look at the Solar Sail Launch System. This sail is smaller but in contrast to the solar sail above directly after launch, enhancement and separation from the launcher in operation mode. But still it carries a docking station with ample solar cell arrays for year long continuing operations such as a sun observing or telecommunication purposes satellite.

self enlarging solar sail, directly operable after launch from Earth and enlargement
In this case the ballast sail foil segments BC and BB are rolled up halfway onto their sail panel rolls 5.13 while the ballast sail segments BA and BD are fully unfurled. The stronger force lever of the sail foils A and D pushes the solar sail downwards at their side of the plane while the weaker forces on sail foils C and B get tilted upwards, were "VR" is the centrum of the upwards tilt.

Underneath Fig. 21a describes the design of a sail panel roll 5.13 on itīs bracket. The end of the bracket telescope segment 5.12 holds a turn motor 5.12.1 which can twist the steering sail foils into a propeller like shape and enables turning the sail around itīs pole.

The two roll motors 5.13.3 are the furling motors which work together with winches on the inner ring construction of the sail craft.

Fig.21b pictures the origin of a bracket telescope segment at the inner ring construction.

panel roll on their bracket with rolling motors and turning motor

to the next Solar Sail Launch System

Fig.1 - Fig.2a-2b - Fig.2c - Fig.2d - Fig.3a-3b - Fig.4a-4c - Fig.5 - Fig.6 - Fig.7 - Inner Ring - Flying Ring - Fig.8 - Fig.8a - Fig.8b - Fig.9 - Fig.9a - Fig.10 - Fig.11 - Fig.10 - Fig.11 - Fig.13 - Fig.14-15 - Fig.16 Mobile Thruster Unit - Fig.17 - Fig.18 Fuelless Steering - Fig.19-21d Solar Sail Launch System

I N D E X - G E R M A N

POST & AUTHOR & Vision
STS - Solar Thruster Sailor
RSS - Ring Skeleton Structure LTH - Launcher Transport Head EFO - Experimental Flying Object RSC - Rotational Slingshot Catapult
L I N K S ENGLISH