Проект "На сахаре в космос".
Второе испытание уменьшенной копии двигателя.
Опять разрыв двигателя во второй фазе, но уже не по шву, а просто по трубе.
Отчёт Накки:
Well, the 2nd 1/4 scale BEM firing is now in the books, having taken
place this past Saturday. Unfortunately, the results of this test were
not as successful as we had hoped for. As has happened with the first
firing, the 1st phase casing burst late into the 2nd phase burn. Again,
the 1st phase burn was beautiful, and the 2nd phase burn looked great.
Clearly the thermal loading of the casing due to the 2nd burn was
extreme, and failure occurred despite measures taken to reduce heating
of the casing (such as phenolic casing liner). In the video, the 1st
phase casing can be seen to discolour (bluing) at the point where it
ruptured. Interestingly, the casing did not burst at the seam but at the
opposite side. However, as suggested by at least two insightful
individuals, EMT tubing is clearly not adequate for 1st phase casing
material, and for the next test, 4130 alloy casing with a much thicker
wall will be used.
Due to a problem with the instrumentation power supply, electronic
thrust and pressure data was not successfully collected. It does appears
that thrust and pressure data was collected by the redundant analog
gauges (videotaped), although this is yet to be confirmed. Good thermal
data was collected this time, which will hopefully prove to be useful
in better understanding the thermal loading that is going on in the
motor under dual-phase operation. If someone has the capability and
would volunteer to attempt to do a thermal analysis of the motor, this
would be awesome.
Three excellent videos of the test were taken. Unfortunately, I was
unable to upload them to the sugarshot site this morning (login problem)
so I temporarily posted them on my own site, and also a photo of Randy &
Peter with the setup.
http://www.nakka-rocketry.net/videos/peterandrandywithbem.jpg
http://www.nakka-rocketry.net/videos/bem2wide.wmv
http://www.nakka-rocketry.net/videos/bem2slow2ndphase.wmv
Once again, a huge thank-you to Randy and Peter for the tremendous
effort & time put into conducting this second test. I know that
disappointment was particularly great for them.
Richard