The Multistage Balloon project is still in the design and planning stage but the design requirements and priorities are taking shape.
Four balloons are still the plan. A center large one to pull the entire assembly aloft then the other three to maintain the altitude. Our goal is to bring the balloon up to the altitude we want then release helium until a neutral buoyancy is achieved. This requires a helium release valve either remotely operated or linked to the altitude sensor. The balloon flies because of the buoyancy force. The buoyancy force is the net force that results from the difference between the mass of displaced air and the total mass of the balloon system. Therefore when the buoyancy created by the helium still in the balloons equals the mass of the air it is displacing then it will stop ascending and remain at that altitude.
You may wonder if the altitude will decrease at night when the sun is not heating the helium. Its true with no sun the balloon cools down. As a zero-pressure balloon cools down, it will float at a lower altitude since the helium can lift less mass at a lower temperature. However our balloon will not be a zero pressure design. It will always have a positive pressure. Heating in sunlight will increase the pressure but If the balloon maintains a positive internal pressure, it will continue to fly at the same altitude even at night because it is the volume of air being displaced which creates the buoyancy not the internal pressure of the helium. With this goal of neutral buoyancy it’s possible that we may need a test flight at lower altitudes,
We have transceivers that have been shown to remotely control at 200 km ranges. The RN2483 module is a transmitter circuit made for slower speed data. It uses the 430MHz band. We will need the two way data link to monitor altitude, real time photos, camera panning, picture capture and to release helium for buoyancy control.
Instrument wise the telephoto IR camera will be the first priority. For that reason we are working on ways to make the balloon as stable as possible. One possibility is a wind rudder assembly attached on top of the instrument pack and rear sails to to keep one side of the balloon constantly pointing into the wind.
Since the camera will be with a telephoto lens it will be so heavy that we can only have one. If the balloon is pointing in just one direction then of course we will need to be able to turn the camera. That means we will need a remote control swivel mount which will be on the bottom.
As of now the launch venue is planned to be Europe. The plan is to use a location that has prominent land features in multiple directions. Hungary would be the right distance from the Mediterranean Sea, North Sea and the Black Sea. We are being ambitious but while we are up there we might as well take some good photos.
The other minor point for launching from Europe is that the 50 cubic meters of helium has been purchased and is in the Netherlands already.
We have asked consulting help from a man with many high altitude balloon launches to his credit. He has agreed to give us any help he can. If possible a member of FECORE will be meeting with him in person and attending one of his balloon launches.