MTA Firing Event, 2023-09-09

by Dave Nordling, President, RRS.ORG

New RRS members, Derek Honkawa, Rick Maschek, Eric Beckner, Mike and Preston Brinker brought a LOX-ethanol liquid engine for static firing at the MTA vertical test stand. I served as the pyrotechnic operator in charge for that day. RRS members, Rushd Julfiker and Bill Inman were present that day to observe along with John Newman of FAR.

Their structure which bolted to the square hole grid supported parallel, same-sized run tanks, each with their own dome-loaded pressure regulators.

Each tank had both manual and remote venting. Each tank also had manual fill and drain valves at the bottom. The engine was supported on an angled sliding rail set firmly against a load cell. The chamber pressure measurement was taken from a side port covered by the ablative liner inside and the line to the sensor head was filled with oil to preserve the measurement.

The team started early that morning following their checklist that began with simple valve checks of the whole system in the completely empty condition. A few minor issues were found and resolved. Low pressure leak checks and valve function tests followed successfully. High pressure lockup testing for leaks were also successful. The team also conducted an igniter test to verify proper burn duration. Upon this careful sequence of initial testing, the team proceeded with propellant loading.

After careful review of their firing procedures, the pyro-op gave permission to continue the test. After air and road checks, a smooth countdown with properly confirmed ignition before valve opening led to a successful 3-second burn tailing off gently. After venting off all stored pressures and confirming a safe system, the test was deemed a success.

This engine was fired a previous time and the team opted to let this single test suffice. The team was well organized, safety focused and communicated well with each other and those on site. It was an excellent example of how to conduct a liquid rocket engine test.

Compton Comet Update, July 2023

by Joel Cool-Panama, Compton Comet Engineer, RRS Secretary

Compton Comet team, including Tre, Joel, and Marx, as well as mentor and RRS President Dave Nordling

The Compton Comet has made a lot of progress in the past few weeks. In that time we’ve managed to have new pipes fabricated for the LOX and ethanol systems, allowing us to finally complete them. We had previously tried to bend tubing by ourselves, since our budget is quite limited. However, it proved to be practically impossible to bend larger tubing without kinking, especially 1″ diameter tubes, with the simple pipe bending tools at our disposal. In the end, these problems were overcome by Waldo Stakes, one of our generous mentors, having the aluminum pipes bent at his own expense. We know from previous quotes for tube bending that this can in fact run into the thousands of dollars, so we are surely indebted to him and his generosity.

We’ve also started, and finished, LOX washing the plumbing, especially the pipes leading to and from the LOX tank. LOX is a very strong oxidizer, and the presence of any remotely flammable material in the plumbing system could spell disaster. For this reason LOX washing is vitally important, and the knowledge of how to properly do it is practically required in rocketry.

With the plumbing all cleaned and installed, we will begin doing low pressure tests of the whole system. This should reveal the majority of any leaks that may be present. Naturally we will need to retest and tighten the whole system once we get it out to the RRS MTA for the hot fire test, but doing a low pressure test now will practically ensure that there are no irreparable problems with the system when we get out there, from where we would likely be incapable of fixing those problems with what tools and supplies we can reasonably bring with us.