by Dave Nordling, Reaction Research Society
The RRS Mojave Test Area (MTA) was used by the student group, Michigan Aeronautical Science Association (MASA) of the University of Michigan at Ann Arbor. Given the remoteness of the RRS MTA and the great distance that the Michigan team was willing to travel, MASA had planned an extended test campaign to use the site for their cold flow and ultimately hot-fire their RP-1/LOX 2,550 lbf liquid rocket engine. Originally planned for a week, the team arrived on Monday, August 16th, and continued to use the MTA site through August 28th. In the end, Michigan faculty called the end of the MASA test series as the new semester was starting and many materials needed to be returned before MASA left southern California.
MASA is a new student group to the society and had very ambitious goals in what they wanted to accomplish in the planned test series. Typically, the RRS will work with new universities and new clients over a period of many months before agreeing to a first test series at the MTA on a weekend campaign. Proper planning is an essential requirement for success and the RRS must become thoroughly familiar and comfortable with all planned use of the MTA site. Like with all attendees to the MTA, indemnification waivers were required from all attendees including spectators. MASA limited their staff to only essential personnel and ran a day and night shift to both safeguard their equipment through the night and provide continuous support to prepare for the next day’s events. The team was able to find rented housing accommodations in the local areas of California City and Ridgecrest.
MASA has had a couple years of experience with their propellant flow systems in laboratory tests at the university and was willing to hold several meetings with RRS members sharing their full test procedures and schematics, and answer questions posed by RRS pyrotechnic operators in advance of their arrival. The MASA fluid systems had many appropriate safety features and used high quality valves and parts. MASA has developed a control system that uses motorized needle valves in place of a pressure reducing regulator for independent propellant tank pressure controls. MASA had conducted many tests of this system and held several tests to confirm proper operation in the early steps of their MTA campaign.
MASA’s system designs also had some problems with the nitrogen compressor (booster) system being unable to operate due to a regulator failure. The team was able to bypass the unit, but it limited the top pressure of the blowdown tests to the bottle pressure (2000 psi). A few changes were necessary for vent line routing to improve operational safety. Remote pressurization operations were safely executed but proceeded very slowly and thus a great degree of boiloff in the LN2 limited run time.
The event was successful in some respects that it gave the students a practical understanding of how to conduct test operations under desert conditions. It also revealed some of the shortcomings in their plumbing design (leaks) which they were able to fix well enough to get to cold flow with cryogenic LN2 and water on the last day of testing (when this report is dated). The cold flow tests provided useful data in their control algorithm which will be useful to the next series of tests. MASA also gained experience in safe cryogenic tanking and operations with these hazardous fluids.
Logistics was a big challenge for the MASA team due to errors in their communication with local suppliers. Nitrogen and helium gas bottles were significantly delayed and cryogenic liquid nitrogen cylinders also were very late to arrive at the MTA. Some of these problems can be easily mitigated for the next test campaign now that relationships have been better established. While MASA was disappointed with some of the outcomes from the test series, they are interested in returning to the RRS MTA in the latter part of this calendar year. This follow-on test series will be discussed at length in the coming months.
The society was similarly challenged in supporting this MASA campaign. The society is grateful to everyone who assisted at the MTA (Osvaldo Tarditti, Waldo Stakes, Bill Inman and myself) or those who gave their comments and concerns (Larry Hoffing, Jim Gross). Several members spent multiple days at the MTA both during the week and on weekends. The RRS provided the necessary oversight during the hazardous portions of the testing campaign which was particularly difficult to schedule during weekdays. The MASA team was very open and disciplined in their interactions with the society. The RRS was also glad for the University of Michigan’s support and communications throughout this event.
It was a challenging event which was made possible by the contributions of many RRS members over many days. Frequent communication between MASA faculty and the RRS was a firm requirement on all days of this tenacious campaign and the MASA team provided daily briefings on their progress.
This testing campaign and current RRS policies will be discussed at the next monthly meeting, 9/10/2021. Pursuant to our mission statement, the society is glad to support projects of this kind to universities capable of conducting safe experiments at our unique testing site and to those who are willing and able to provide the society with sufficient advance notice to review their reports, schematics and inspect their hardware. This campaign is firm proof that we will need more licensed pyro-ops and more members available to support any similarly extended test series in the future if they are accepted by the council. By building and enforcing a consistent and fair policy for all new and prior clients, the RRS can better operate to the benefit of everyone.
All requests to use the RRS MTA must be made to the RRS president and reviewed by the executive council. For any questions about this test series or any future test series, please contact the RRS president.