Last week Capsuleman did not explain how the top dome was jettisoned in order to deploy the drogue for space capsule Tycho Deep Space. So it is my duty to continue where Capsuleman failed.
In short, the top dome of the space capsule must be jettisoned to deploy the drogue. The top dome is fixed at 3 locations on top of the main parachute compartment which is a fixed part of the overall capsule structure. We have to come up with an idea which can hold the top dome in place during flight and easily leave the capsule when ordered to.
During the development of my previous spaceship Tycho Brahe-1 the deployment of parachutes were done by keeping the parachutes “trapped” behind thin sheets of aluminum, found at an off-set printing company. The aluminum sheets are 0.3 mm thick and were locked to the side of the ship using pop rivets. By creating an internal chamber pressure by nitrocelluloses detonation the parachutes were forced to remove the aluminum sheet by the rivets and leave the ship.
The system can be seen here during an all up test on Tycho Brahe-1
This principle was tested many times and where found to be trustworthy. So, I would like to use the combo of aluminum sheets and nitrocelluloses once again for the top dome but in a slightly difference configuration.
The idea is to fix the top dome using 3 regular bolts going from the top dome flange to the fixed top flange of the main chute compartment. However, in between the flanges I will have an unknown number of layers of aluminum which will be deformed and destroyed when creating pressure using nitrocelluloses inside the top dome.
Top dome bolting configuration. Sketch: Kristian von Bengtson
Top dome bolting configuration. Sketch: Kristian von Bengtson
Aluminum plate deformed letting the bolt passing through. Image: Kristian von Bengtson
Very soon I will try to perform the first test with this configuration. Inside the top dome we will place a replica of the drogue and x grams of nitrocelluloses added small igniter’s. We will fix the top dome starting with 1 plate of aluminum and cross our fingers. The test will have to be performed numerous times until the correct amount of nitrocelluloses and aluminum plates are found.
It is of course important to find a way to control the top dome when blasted off the space capsule to avoid damage to the dome, capsule and ourselves.
In the process we also have to consider how the keep the dome from leaving the capsule by itself when going into space if it contains 1 atm when locked and sealed on Earth. The previous parachute compartments on Tycho Brahe were added went holes to avoid positive delta-pressure during flight. A similar idea might apply to this top dome.
I really love this phase in the development. Having ideas on paper is great but when you slowly become ready for an actual test you touch the real essence of this project.
Only the test will show how great your ideas really are… exciting!
Ad Astra Kristian von Bengtson
