Everybody’s favourite amateur Danish rocket group had another engine test quite recently – while not everything went to plan, nobody could say it wasn’t spectacular.
The test on August 16th was meant to try out the latest incarnation of Copenhagen Suborbital’s HEAT2X rocket, marking the first large scale test since CopSub’s move to their new facilities. Unfortunately the engine failed in a quite spectacular (but relatively safe!) manner, leaking fuel that started a fire largely destroying the rocket’s electronics and other sub-systems.
Copenhagen Suborbitals were lucky in that, being a rather media-savvy bunch, they had a whole lot of cameras filming the test that have proven invaluable, both in providing useful information and some incredible advertising material for Go-Pro, after one of their cameras survived being engulfed in some incredible heat with enough memory intact to recover test footage.
A few days after the test, CopSub did an extremely thorough autopsy of the rocket that revealed previously undetected manufacturing flaws caused the demise of the TM65LE engine, dumping all of the rocket’s fuel at once.
The TM65LE is a fairly standard regeneratively cooled engine design. In regenerative cooling, the rocket’s own fuel acts a coolant, with the fuel passing through passages in the engine’s nozzle, absorbing heat and cooling the nozzle as it does so, before entering the engine’s injector plate where it is forced into the combustion chamber itself where it mixes with the oxidiser and combusts.
The TM65LE includes a large number of welds in its construction (perfectly normal) and it seems that several welds in key areas did not penetrate the entire depth of the two pieces being welded, resulting in a welded structure of only partially the nominal strength. As the rocket was started, fuel entered the nozzle skirt under pressure which the incorrect welds could not withstand, blowing them open and spilling a good proportion of the rockets fuel all over the floor of the test stand and subsequently engulfed the rocket in flames.
This fire subsequently destroyed large amounts of electronic systems in the rocket, although CopSub is planning to recover some test data from chips on scorched circuitboards by desoldering the chips and mounting them to a new board. Having completed the autopsy, this TM65LE engine is apparently destined to become a display piece.
I am not aware of any word from CS as to their direction following this test, although given their history with liquid rockets another one seems likely. Kudos to them for being so open with their information following what would otherwise be a rather embarrassing incident.