by Dave Nordling, RRS.ORG

The RRS held its first launch event of the new year, 2020, this Saturday, January 18th at the MTA.  As part of the RRS commitment to being more active throughout the year, we have made a specific point to hold an event early in the year.  The weather was perfect. Low winds and slightly cool temperatures made for a great day to launch.

We had a few different projects at this event.  We also used this event as an opportunity to do some minor site improvements including the addition of a pair of standing benches.

RRS member, Keith Yoerg had a couple of high powered rocket flights.  He had two successful flights before we were told that the FAA waivers that day were cancelled due to adjacent activity at Edwards AFB.  We are thankful for our neighbors at FAR for letting us know, but in the future the RRS should be better informed of such important notices.

Both dual-deploy recovery systems in his rockets worked just fine and the rockets were found and brought back right away.  The telemetry data showed a nearly 4000 foot altitude with a top speed of Mach 0.6 was reached with his I-sized motor, very comparable to the RRS standard alpha. 

Wolfram and Marianne Blume made their first journey to the RRS MTA from south Orange County. Wolfram had begun his preparations for his first launch of the Gas Guzzler ramjet from our 1515 rail launcher when we got notice that all flights were cancelled that day.  Wolfram is willing to come back at a later date which is in planning.

The Gas Guzzler rocket is a two-stage rocket with a commercial high-powered solid motor and a gasoline fueled ramjet second stage. Wolfram has a lot of systems checks to do before proceeding with the ramjet flight.  This first flight is to be a demonstration of the vehicle booster, staging mechanism and the recovery systems on each stage.  The ramjet will be filled with an equivalent weight of water to keep the vehicle balanced similarly to how it will be in flight.

The RRS has not yet approved the flight of the fueled ramjet flight, but is happy to support the ambitious goals our new member projects like Wolfram’s with system tests. We look forward to seeing how this first flight will go in the near future.

The liquid rocket team at Loyola Marymount University (LMU) came out to visit the vertical test stand at the RRS MTA and discuss many of the important details of liquid rocket operations with our pyro-ops.  LMU is working hard to get into static hot fire testing of their kerosene-LOX rocket motor design by May 2020 at the RRS MTA. 

The RRS is supporting many liquid rocket teams at the MTA for the Base11 competition and in supporting their own university goals.  Making a site visit to the MTA is a good way to conquer the many practical challenges that each team faces in making their systems work.

The last project attempted at the RRS MTA that day was the commercial hybrid motor that Larry Hoffing and I have integrated into an old 2.5-inch rocket body.  I bought a Contrail Rocketry H222 38mm 16-inch motor kit with a reload pack to get the fill lines and reloadable hybrid fuel grains.  This was an ambitious project to assemble over the end of the year break.

Unfortunately, I was not able to secure a parachute deployment system. Hybrid motors do not have ejection charges so you must have an autonomous system. The Stratologger CF model was recommended, but wouldn’t arrive in time for Saturday’s launch. In any case, the launch would have been cancelled anyway.  I opted to do a simple static fire and mount to the 1010 rail we had deployed.

The H222 motor assembly process was completed per the instructions. The assembly is a very tight fit so a generous use of Krytox and Mobil 1 lubricants is strongly recommended.  In my next build, I may make a pusher tool to make the next assembly easier to do. With the clear vent line strung up through the top of the rocket tube and the fill and igniter lines sticking out through the graphite nozzle, the motor was loaded and ready.

The RRS was kind enough to invest in a nitrous bottle from Nitrous Supply Inc. in
Huntington Beach, CA. The auto racing has a lot of nitrous accessories that work very well for amateur rocketry.  The RRS is grateful to Nitrous Supply for their excellent advice.

The RRS also invested in a solenoid valve manifold from Pratt Hobbies in New York state.  Doug Pratt was great support and provides reliable hardware. It’s important to know your gas bottle connections. CGA 660 type connectors are used in nitrous oxide (N2O) bottles used in the racing industry.  CGA 326 connectors are different and are found on nitrous bottles used in the medical and dental industries.  We opted for CGA 660 type which doesn’t require a medical business license to acquire due to the nitrous oxide being denatured with sulfur dioxide. Harmful to people, harmless to the rocket combustion.

Both the bottle and valve manifold mated well and I tested the 12 VDC solenoids separately using the bare wire leads on my truck battery.  I was going to do a leak check on all fittings and connections, but I forgot my leak check fluid bottles at home.  I was willing to tolerate a little leakage in the outdoor environment after I verified the snug fitting of all parts.

It was for lack of a proper Parker Prestolok fitting that I was unable to complete the fluid circuit and because of this no static fire at the event would occur.  As I later found out, these fittings are available through Grainger but it would take too long to acquire as they are often not in stock.

The 3/16” OD nylon tubing for my injector is also not very common. Parker Parflex NB-3-046 thick wall tubing can be bought through pneumatic system suppliers who are distributors for Parker Hannifin.  Having a longer length of this 3/16“ OD  tubing would have been ideal.  Instead, I found 100 foot rolls of 1/4” nylon thick wall tubing at Home Depot but I needed to connect between tube sizes.  With a brass  1/8” FNPT coupler (also found at Home Depot) you can adapt between 3/16” and 1/4” fluid lines.  I was missing a pair of 1/4” tube to 1/8” NPT Parker Prestolok connectors to complete the set.

Larry and I will regroup and prepare for the next launch event at the RRS MTA which will be in the next two weeks.  Osvaldo was going to make a special firing box for hybrid rockets with three switches (fill / ignite / vent) and the same key interlock.

The RRS MTA will be hosting USC RPL for their latest solid rocket motor design (1/25/2020) and UCLA for their next liquid rocket motor static hot fire (2/1/2020). 

It was a reasonably successful day and proof that January is a great month for an MTA launch event.  The RRS is grateful to our members who came out to the site to help with assessing site improvements at the MTA which will hopefully begin this year.