R-8 Test Results

Third test of Casing 2.0, this time with cast gypsum nozzles

After some consideration and experimentation it was decided that a cast concrete nozzle might be better than a bare washer going forward

R-8 was made to test our cast gypsum nozzles, and is the first test to be conducted in 2021

First some information about the nozzles:
Since concrete was not available gypsum was used, which was cast into 3d printed molds covered with a small layer of Vaseline to aid in separation

These molds were also designed in such a way as to allow a small metal washer to be placed on them, while still allowing the mold to be removed from the bottom without getting stuck

3 Molds with gypsum cast into them
2 finished nozzles

A total of 8 were cast, 4 with rings and 4 without
They proved tricky to remove due to a slight expansion holding them in the tube and a high fragility
This resulted in only 2 getting out in one piece (of which one broke while mounting), and the ones with the rings to be discarded due to them not binding to the metal or having enough spare room to fuse around it
This and the results of the test have made me stop considering gypsum, so concrete will be acquired and some testing will be done with composites of gypsum and binder

R-8 with loose nozzle assembly
Clay bulkhead (glued to improve strength and prevent leakage)
Nozzle with retaining ring after mounting

As for the test itself:

Note the increase in flame width over time
R-8 Without Fuel16.80 g
R-8 With Fuel30.04 g
R-8 Fuel13.24 g
R-8 Fully Assembled35.30 g
Peak Thrust308 g
All values are approximate, im only human

As you can see from the flame profile and the peak thrust the nozzle failed substantially
It did not blow out, as a clay nozzle might, but it did ablate away very quickly, increasing the throat diameter to the point of uselessness

Picture of R-8 in action provided by my grandpa who was attending the test (Thanks!)

Another problem which occurred -unrelated to R-8- was that due to the 2 ICBM-B alligator clips shorting during the first ignition attempt relay 2 broke, requiring some field rewiring to resolve
The battery luckily seems to still be fully functional and the only functionality that is now missing is the continuity light, this will be fixed before the next test (as of R-9 this is yet to be fixed, and no plans have been made on how and when to fix this issue)

As always, the raw data (In a 7-Zip archive):

I also recommend Notepad++ for viewing and editing

Next step is improving the nozzle design, using a different mixture and maybe using smaller washers to allow for better structural integrity

I also made a lot of small tweaks and improvements to various things, which have been posted in a different article, which can be found here

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