Every manned space capsule carrying people to into orbit for scientific research must return its human cargo to safety, and so needs to land on ground or splash down in water.
Splash tests are one way of making sure that a capsule slated to land in the water floats, and ideally, lands upright without breaking.
Existing splash test facilities around the world, such as the Hydro Impact Basin Facility, NASA’s Langley Research Facility in the US, are custom gantry-like structures standing over pools.
The gantry being used by Copenhagen Suborbitals, was originally used for shipbuilding. It has a 1000t capacity and 77.5m height under hook. It runs on rails to service different production halls, lifting ship decks and whole engine rooms over a dry dock during construction.
The gantry is an unusual one, equipped with more hoists than a normal gantry to enable building ships so they balance correctly. "Most shipyard gantry cranes have one upper trolley with two hoists and one lower with one hoist," says Peter Blazejewicz, transport manager of Lindoe Industrial Park.
This gantry is special. "It is basically a typical shipyard gantry crane but it’s special in the way that it has six main hoists configured in two lower and two upper trolleys," says Blazejewicz.
The hoists balance starboard and port blocks of the ship in midair, with each suspended by three hoists in a three-point configuration. "There are actually two main beams with a slit between them. Under one beam we have the driver’s cabin that can travel across the beam and an auxiliary hoist on the other beam," says Blazejewicz. Blazejewicz is a friend of Kristian Von
Bengtson, co-founder of Copenhagen Suborbitals.
He agreed to loan Von Bengtson the giant gantry so that the group could meet its goal of building a manned spacecraft on the cheap.
A former gantry operator himself, he is overseeing gantry operation during six drops: four parachute tests with 160kg ballast and two drops of the capsule.
"So the splash test will basically be dropping the spacecraft from a calculated height," says Blazejewicz. "We will do at least two drops of the capsule; one vertical and one ‘swing-style’.
"The parachute drops are similar to the capsule drop, save for that they are not using two hoists as it will not need to impact at an angle: It will just be dropping from the highest position. We will need to drive the hoist to a suitable position, which will depend on the direction of the wind on that particular day, and we will need to find a place where it has a clear landing spot," says Blazejewicz.
The space capsule isn’t just being dropped: its fall is carefully planned. "What were going to do is drop the spacecraft from a certain height, so the speed of impact will be the same as if it were landing with a parachute."
The decisions about height and angle of both drops will be made by Suborbitals but Blazejewicz is advising on how to suspend it and facilitating the use of the gantry.
The gantry itself is controlled from a cabin under the main beam. "There will be someone in the cabin, but he will be above the capsule. Everybody else will be monitoring from a safe distance."
"Me and my guys will prepare the crane and the rigging, working with Suborbitals. When they prepare their stuff we will hoist the crane and configure it to the right position, and then they will remotely release the capsule," says Blazejewicz.
Swinging the capsule will require rigging it with two hoists so it hangs at an angle. "The capsule will be hoisted up using one hoist, swung out at an angle by a drag line from a hoist opposite, 18m away."
Using only the force of gravity, it will swing towards the water in the dry dock at a precisely calculated angle.
Blazejewicz is charged with ensuring that the drops are safely conducted. "The overall responsibly for the safety of the operation is mine. And to say when e can go."
The operation is safe despite dynamic loading because the capsule mass is relatively small and people will be far away, he says.
"We worked it out, although usually you don’t drop anything from a crane because there will be a counterforce that will impact the crane."
"What we calculated there is that the speed and masses involved will be so small in comparison to the crane that they are in the same range as the casual "bumps" when we handle our rigging gear."
"We will configure the hoists and attach the capsule while it’s on the ground, but by the time we lift things in the air, there will be no people in the vicinity."
The capsule will be released from the hoist when Copehnagen Orbitals sends a remote-controlled signal to an exploding bolt, severing the line suspending the spacecraft at an angle.
"We’ll first release the line by just blowing away a bolt with pyrotechnics, a little explosive charge and the spacecraft will start to swing and by the time it reaches the bottom of the swing we will blow the second bolt." When the capsule reaches the water, it will have the vertical and horizontal speed that the group wants.
"It will simulate the spacecraft falling in the sky and the wind speed will cause it to impact at angle. They want to see how the space craft will react; for example by toppling or going
underwater," says Blazejewicz.
"In the ideal world it will just bounce up and down a couple of times and will stay floating in the right directions with the top pointing upwards, but I think we are gong to try to provoke it to topple over and land upside down because there is a system of bags that will automatically inflate and upright it, so it would be nice to test them."
Since Hoist completed this interview, the parachute tests have concluded successfully, Blazejewicz confirms.
"This was done Saturday, with perfect wind conditions, giving a gliding path almost parallel to the longitudinal axis of the drydock."
