Okay, Copenhagen Suborbitals had an engine test, which generated some
rather spectacular video

https://www.youtube.com/watch?v=f-4n-2MtECE

First you see the test (all 17 seconds) in real time, then
repeated at 240 fps. Apparently those GoPro Heros really hold up ....

Then comes the post mortem:
http://copsub.com/autopsy-of-heat-2x-and-tm65le/

Seems there were a few welds on the nozzle cooling jacket which
did not get full penetration.

to quote

«Summary

The results of the autopsy are consistent with a scenario in which the
engine compartment had a leak of fuel already in the pre-stage due to
a damaged packaging under the fuel pre-stage valve. As the pressure
increased nominally at the start of the main-stage, the undersized
spacers between the inner and outer walls of the cooling jacket as
well as the poor and undersized welds caused the cooling jacket to
burst open. Fuel ran out into the open air without passing through the
combustion chamber, while the LOX/GOX unreacted ran out through the
nozzle. Both contributed to the outer fire, which in turn ignited the
fuel which escaped through the hatches from the engine compartment.
Blow back through hatches created a secondary fire in the engine
compartment. We could not detect a leak in the LOX system.»

Interesting, to me, is the robustness of the electronic components
- at least the flash memory chip is expected to provide usable data,
once disconnected from the burnt board mounted on a working board.

okay, play safe out there.
--
pyotr filipivich.
Discussing the decline in the US's tech edge, James Niccol once wrote
"It used to be that the USA was pretty good at producing stuff teenaged
boys could lose a finger or two playing with."