VAPOR

Vehicle for Atmospheric Probing and Outspread Research

Instruments

From the concepts, we now have masses and dimensions for each set of instruments required for the atmospheric vehicle. These were set in a layer and the blimp built around it.

Power System

This is the power use profile for the blimp when relying on its battery on the night side of Venus. This gives 4 days of data gathering at the normal altitude, before the air currents push the blimp back into the day side. During the deployment, power is still being routed to the instruments to take data from the deployment altitude.

Thermal management System

  • Active only at 50 km altitude on the day side
  • Cooling 100 W of power use plus 280 W from ambient temperature
  • Peltier modules covering 0.658 m2 required to cool to 300 K
  • 5 kg assigned for modules and heat pipes

Descent and Deployment

  • COPV vessel at 202.8 bar to contain N2 to fill envelope
  • Thermite to reheat gas from 55 K to ambient after pressure drop
  • Parachute of 5.5 m diameter to slow descent to 10 minutes

    • The blimp starts deployment at 65 km altitude, using a parachute of 5.5 m diameter to slow the descent. The envelope then takes 10 minutes to inflate while it falls, COPV filled with nitrogen to start pressurising the envelope. The envelope will be fully expanded at 55 km, with empty ballast tanks. Due to the pressure drop, the nitrogen temperature drops to 55 K, so a channel of thermite is lit upon release of the gas to restore the temperature.

Stowed CAD Drawing

Here’s the assembly drawing for the blimp before deployment. You can see why the nitrogen is stored at such a high pressure, it’s size is a considerable proportion of the volume available in the aeroshell. The thermite channel is located here, with the payload bay situated above.

Deployed CAD Drawing

3 chambers: 2 fore/aft CO2 bladders and main. Main envelope inflates up to 520 m3, at 55 km. The lower cross section shows the volume of each of the tanks at the lower altitude, where the ballast is fully inflated with atmosphere. The nitrogen mass inside the main envelope remains constant. Bladders inflate up to Pressurised 357 Pa above ambient. Dyneema is 0.076 mm thick, storable in 41L.

A polymer membrane gas separator enables the envelope to be refilled by 1 % each day. At the current mass, the CO2 tanks are empty at the design altitude and fully expanded at the lower altitude. The motors at the side will be folded away for stowage. To meet the requirements for this vehicle, the directional control is done by using differential thrust on the motors to turn and stabilise the aircraft as opposed to using an empennage and rudder.