Rocket builders test parachutes with human test subjects

29. marts kl. 14:31
Rocket builders test parachutes with human test subjects
In the back, from the left: Hans Jørgen Winther, Mikkel Køhler Caspersen, and Mads Stenfatt. In the front: Ahmad Rahman. They stand next to the parachutes for the space capsule after a successful test of the opening sequence of the three main parachutes. Illustration: Henrik Jordahn.
Real people are used as guinea pigs to test parachutes made to slow down space rockets during landing.
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In a YouTube video posted by Copenhagen Suborbitals, several people are seen jumping out of a plane.

One is holding onto an orange parachute that fails to fully open. He suddenly lets go of the handle and free falls for a few seconds before another parachute finally opens.

It may look dangerous, but everything is under control, says Mads Stenfatt, the person in charge of parachutes in the rocket enthusiast group Copenhagen Suborbitals.

“After all, one learns from mistakes. And we do everything we can not to hide the things we learn from.”

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The video shows a test of parachutes that Copenhagen Suborbitals is developing for its Spica rocket.

According to the plan, Spica should land safely in the Baltic Sea after completing the first Danish manned spaceflight—and Copenhagen Suborbitals is behind the whole project.

Even before Spica reaches its maximum altitude of 105 kilometres above Earth, the capsule with the astronaut will be ejected from the rocket.

Copenhagen Suborbitals’s space flight system will consist of two components that are supposed to land in water with the help of parachutes. One of them is the space capsule, which will carry a Danish amateur astronaut, and the other is the rocket itself.

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Crazy scenes in Odense—Copenhagen Suborbitals tests the parachutes that should one day bring the Spica rocket safely down over water after its spaceflight:

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When the two components separate, the rocket will turn nose down towards the ground again.

Before the rocket hits the surface of the water, a braking parachute—or drogue—has to slow it down.

The group tests the parachutes by having experienced parachutists jump out of an aircraft at an altitude of 2,500 metres. After falling down 1,200 meters, the jumpers let go of the parachutes, after which they open completely ordinary sports parachutes, which they then land with.

Only way to carry out tests

Copenhagen Suborbitals is based on the idea of having ordinary people develop, build, test, and ultimately man the spacecraft. And that can cause challenges, Mads Stenfatt explains.

“When we started exploring how we could do this, we found out that there is some legislation in the field of aviation that prohibits civilians from throwing things out of a plane,” he says.

It is the Air Navigation Act that contains restrictions on civil flights. This means that Copenhagen Suborbitals cannot test the parachutes with the actual weight of the rocket.

Mads Stenfatt flies side by side with parachutist Ahmad Rahman. They are testing the three main parachutes that will be used for the space capsule.
Illustration: Henrik Jordahn.

The only possible solution is testing with parachutists.

It is experienced members of the Odense Skydiving Center who jump with the parachutes.

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Meanwhile, Mads Stenfatt sits in the plane and throws the test parachute out after the parachutist, so that it safely comes out of the plane and unfolds. Then he jumps out of the plane himself and follows along on the way down, observing the performance of the parachute.

When Copenhagen Suborbitals tests parachutes, the parachutist typically jumps out of the plane at an altitude of 2.5 kilometres. In the beginning, the parachutist had to let go of the test parachute at an altitude of 1,500 metres and then open a regular parachute at an altitude of minimum 1,000 meters. This is because, according to the legislation, they are not allowed to land with a test parachute.

“And then, after a great many jumps with the current model, we have slightly adjusted the numbers, so we now let go of the test parachute at an altitude of 1,200 meters instead. So we get 300 meters more to observe the behaviour and a bit more time for measurements,” Mads Stenfatt says.

Legislative restrictions

Due to the current legislation, the first landing with the parachute will take place when Copenhagen Suborbitals at some point carries out a launch from the Baltic Sea.

The last successful landing was in 2018, when the Nexø II rocket landed with a parachute at a speed of seven meters per second.

Even though the landing went well, Mads Stenfatt still wished there was an opportunity to test the parachutes with a correct mass hanging under them instead of a parachutist.

The Spica space capsule weighs approx. 350 kilogrammes, and Mads Stenfatt would like to test the parachute with that weight before the final flight.

From left to right: Mads Stenfatt, Ahmad Rahman, and Jakob Sparvath. On the way back to Odense Skydiving Center’s clubhouse after a successful test.
Illustration: Henrik Jordahn.

According to Mads Stenfatt, Copenhagen Suborbitals has been quite good at predicting where the parachutes will land during the tests.

With a change in the legislation, it would simply require a landowner to make a large field area or equivalent available for the parachute to land with the required mass.

“So it would be great to have some kind of approval model where we could do that. I definitely dream of that,” he says.

Flying Spaghetti Monster

After the planned spaceflight, both the space capsule and the rocket are supposed to land with parachutes.

First, the space capsule is braked with a so-called ballute, an inflatable parachute.

It must be able to withstand a very high speed and be stable for the sake of the astronaut in the space capsule.

The design of the ballute has been determined for a long time, but the parachute for the rocket is a different story.

For safety reasons, there must be a large distance between the two objects when they land in the sea at some point. Therefore, the rocket’s parachute is deployed late during the descent, so that it gets as far ahead as possible.

This requires a specially designed parachute because the atmosphere will be dense and the speed high. There are currently two parachute designs in consideration for the Spica rocket.

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Last year, Copenhagen Suborbitals tested different versions of the so-called Flying Spaghetti Monster. One had more air resistance than the other.

One of them has been named the “Flying Spaghetti Monster” by Copenhagen Suborbitals.

The name comes from the parachute’s characteristic air holes. Officially, this type of parachute is called a ribbon hemisflo drogue.

The Flying Spaghetti Monster is apparently feeling mischievous, because as one can see in the Copenhagen Suborbitals video, it does not behave quite as it should.

“It’s only the top half that opens properly and catches air. In the lower part of the parachute, the pressure is not high enough, and the parachute does not behave optimally,” Mads Stenfatt explains.

The final parachute design

The next time Copenhagen Suborbitals tests their parachutes, it will be with a new and final version of the Flying Spaghetti Monster.

“I’m going to close it more on the sides and at the bottom than previously. And I hope that’ll be enough to catch enough air,” Mads Stenfatt says.

Mads Stenfatt is working on a prototype of a ballute (a special braking parachute) to be used for the space capsule.
Illustration: Henrik Jordahn.

Copenhagen Suborbitals calls the competitor to the Flying Spaghetti Monster the “Onion” because of its round shape. It is a Supersonic X parachute design.

It is easy to make, but is not often seen used by others. That is why Mads Stenfatt is wary of using it.

The final decision will be made after a new test in Odense.

In Copenhagen Suborbitals, it is ordinary people who develop and build the rockets and support the project financially.

“And fortunately, there are many who are willing to pay a little extra if we reach out and ask for something specific,” Mads Stenfatt says.

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