An Airship Pla orm vs A Tethered Balloon Pla orm for Science Applica ons
Robert Fesen Dartmouth Advantages of a Tethered Balloon Pla orm
A high al tude balloon pla orm that is tethered to the ground doesn’t have some of the mass associated with an airship’s power and recovery systems.
‐ no propulsion motors ‐ no propellers ‐ no large solar panels to power the motors ‐ no ba eries needed to power propulsion at nigh me
‐ maybe no parachute (?) ‐ maybe no balonet and associated mechanisms (?) A Comparison of High Al tude Pla orms for Science Applica ons
Item Airship Tethered Balloon Al tude Range < 75 k 65 k +
Payload mass ~ 40 kg > 100 kg ? (Hale‐D, HiSen nel80)
Sta onKeeping only if winds < 10 m/s its tethered
Cost $35M for HALE‐D unknown, probably less
Dura on days to weeks? days to weeks ? A hybrid tether idea is the “StarLight” high al tude pla orm under development by Global Near Space Systems Inc (GNSS). It consists of a slightly aerodynamic balloon which is a ached to a solar powered propulsion unit hung below. Starlight with narrow‐wing, and with wide‐chord, light‐ high‐speed configura on… gathering configura on This arrangement solves several problems associated with the mul ‐ balloon tethered to the ground approach.
• No winch needed • No avia on hazard issues associated with a grounded tether line • Avoids most issues regarding stormy weather • Tether wind loading is modest since tether al tudes > 65 k • Simpler deployment process with fewer elements
Separa ng the propulsion unit & PV panels from the balloon: ‐ propulsion propellers located in denser air and in lower winds ‐ propulsion unit could act like an “anchor” to the balloon ‐ PV panels competely unblocked by the balloon
I’ve run some calcula ons and in the next slides I show the results.
65,000 : Spherical Balloon Drag Force @ C = 0.50 5 km/s 10 km/s 20 m/s 54 millibars D 66 k D = 20 m 3 170 N 680N 2700 N 0.086 kg/m Disp:115 kg
C = 0.5 Mission D 65 k 56 millibars D = 1.0 m 0.091kg/m3 payload 1 N 3.6 N 14 N L = 1.0 m
3 k (1 km) 3 mm tether CD = 0.5 2 N 6 N 26 N 6.8 kg wt L = 1 km MBS = 1500 kg
CD = 0.10 0.1 N 0.4 N 1.5 N 64 k 59 millibars D = 0.5 m Propulsion 0.095 kg/m3 L = 2.5 m vehicle 65,000 : Aerodynamic Balloon Drag Force @ C = 0.10 5 km/s 10 km/s 20 m/s 54 millibars D 66 k D = 7 m 3 4 N 17 N 66 N 0.086 kg/m L = 30 m Disp: 100 kg
C = 0.5 Mission D 65 k 56 millibars D = 1.0 m 0.091kg/m3 payload 1 N 3.6 N 14 N L = 1.0 m
3 k (1 km) 1.4 mm tether CD = 0.5 1 N 3 N 13 N 1.1 kg wt L = 1 km MBS = 200 kg
CD = 0.10 0.1 N 0.4 N 1.5 N 64 k 59 millibars D = 0.5 m Propulsion 0.095 kg/m3 L = 2.5 m vehicle 65,000 : Best Aerodynamic Shapes Drag Force @ C = 0.05 5 km/s 10 km/s 20 m/s 66 k 54 millibars D D = 7 m 0.086 kg/m3 2 N 9 N 33 N L = 30 m Disp: 100 kg
C = 0.35 56 millibars Mission D 65 k D = 1.0 m 0.091kg/m3 payload 0.8 N 3 N 9N L = 1.0 m
3 k (1 km) 1.4 mm tether CD = 0.5 1 N 3 N 13 N 1.1 kg wt L = 1 km MBS = 200 kg
C = 0.05 64 k D 0.05 N 0.2 N 0.8 N 59 millibars D = 0.5 m Propulsion 0.095 kg/m3 L = 2.5 m vehicle 90,000 : Spherical Balloon Drag Force @ C = 0.50 5 km/s 10 km/s 20 m/s 17 millibars D 91 k D = 40 m 0.027 kg/m3 210 N 850 N 3400 N Disp:285 kg
C = 0.5 Mission D 90 k 18 millibars D = 2 m 0.028 kg/m3 payload 0.5 N 2.0 N 8 N L = 5 m
25 k (7.5 km) 1.7 mm tether CD = 0.5 4 N 16 N 64N 13 kg wt L = 10 km @ 0.05 kg/m3 MBS = 300 kg
65 k 56 millibars C = 0.10 Propulsion D 0.091 kg/m3 D = 0.5 m vehicle 0.1 N 0.4 N 1.5 N L = 2.5 m 90,000 : Aerodynamic Balloon Drag Force @ C = 0.10 5 km/s 10 km/s 20 m/s 17 millibars D 91 k D = 15 m 3 6 N 24 N 95 N 0.027 kg/m L = 60 m Disp:285 kg
18 millibars C = 0.5 Mission D 90 k 0.028 kg/m3 D = 2 m payload 0.5 N 2 N 8 N L = 5 m
25 k (7.5 km) 1.7 mm tether CD = 0.5 4 N 16 N 64 N 13 kg wt L = 7.5 km @ 0.05 kg/m3 MBS = 300 kg
65 k 56 millibars C = 0.10 Propulsion D 0.091 kg/m3 D = 0.5 m vehicle 0.1 N 0.4 N 1.5 N L = 2.5 m 90,000 : Best Aerodynamic Shapes Drag Force @ C = 0.05 5 km/s 10 km/s 20 m/s 17 millibars D 91 k D = 15 m 3 3 N 12 N 50 N 0.027 kg/m L = 60 m Disp:285 kg
18 millibars C = 0.35 Mission D 90 k 0.028 kg/m3 D = 2 m payload 0.2 N 0.8 N 1.6 N L = 5 m
25 k (7.5 km) 1.7 mm tether CD = 0.5 4 N 16 N 64 N 13 kg wt L = 7.5 km @ 0.05 kg/m3 MBS = 300 kg
65 k 56 millibars C = 0.05 Propulsion D 0.091 kg/m3 D = 0.5 m vehicle 005 N 0.2 N 0.8 N L = 2.5 m Airship
The top balloon might have a size like HiSen nel80 but without the propulsion motor, parachute, and heavy ba ery packs.
HISen nel80: 60 m long, 15 m wide Payload mass 40 kg Solid mass = 500 kg Helium mass = 100 kg Drop Ballast ~ 20 kg