Preparations for Second Pressure Test

The second test box has now been completed. This box is intended to test the hatch with pressure and cold.

This is a process of iterative design and testing. The first test box showed that the fixed-window design is adequate but the box itself failed. This new one has much more carbon fibre layup in the area that failed. It actually has less carbon in the main body of the box – if we can make the plane lighter, we will do so.The test hatch has been constructed in exactly the way that we expect to make the flight article. We have refined our technique for forming the Makrolon (polycarbonate) into the window shape. The window has been bonded into the hatch in the same way as the sucessful fixed window. Once again, we have two identical panes of Makrolon, each of which is capable of holding the full test pressure on its own.

Tim holds up the hatch for Greg to inspect it.

Morgan holds up the completed hatch, ready for installation.

The hatch has passed the initial test – it does hold pressure. In fact the result was better than we could have hoped for – there was no measurable leak after 2 hours.

Morgan inserts the hatch into the test box and sets the hatch into place.

Next week we expect to test the hatch at full proof-test pressure and 100 degrees below zero. I’m not really sure what to expect – the box should hold a higer pressure than the previous burst pressure but we don’t want to burst this one right away before doing more long-term tests.

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