An update from Roberts Rocket Project, of which he has successfully carried out an all up static test of his liquid-fueled rocket, soon leading to flight.
I finally got a chance to run the static test of the flight vehicle this weekend. From a vehicle perspective, it was very good and I’m ready to move forward with getting it ready to fly. However, from a test operations perspective, there were a couple of issues…
Test operations wise, there were two issues. The first is that I had trouble getting a full LOX load, even with the modified sequence of closing the vent valve before closing the dewar. The tank should hold about 17 seconds of LOX but it ran out at around 12 seconds which caused the rest of the fuel to burn outside the chamber until I manually issued an abort…
The other test issue was with the helium pressure. I thought I had enough high pressure helium on hand but when I loaded the vehicle helium tank, I only got it up about 2080 psi where I was hoping to load it to at least 2500 psi…
A few niggly issues that were sorted, but otherwise a great success from Robert. I have been following his progress for a few years now, so it is great to see him reach an all up test of the rocket, and now just to see it fly!
A new update from Robert as he continues his work on his liquid-fueled rocket, working towards an all up static test soon.
The test stand blast deflector for vertical testing is complete. It uses three 24 x 24 x 2 inch concrete pavers at 30 degree increments to deflect the exhaust horizontally down the flame trench in my test pit. The frame is made of 1.5 x 3/16 inch steel angle. A negative step of about 0.1 inches between pavers will hopefully minimize erosion on the leading edge of the downstream ones.
Roberts also goes into detail about some of the flight avionics and some engine maintenance.
His updates and work are very professional with loads of information, check out his site here.
Robert has posted a new update on his liquid-fueled rocket project.
Since the last update, he has built and tested a magnetic breakaway connector to provide power and other services while on the pad, as well as the GSE the rocket requires.
A very clean and nifty idea for a breakaway connection.
An update on Roberts rocket project as he works towards the flight of his 250lbf liquid fuelled rocket. Robert has been working towards a full up static test of the rocket, with thoughts on how to use his existing infrastructure to conduct this.
The existing test stand structure will be reused but extra components have been added to secure the rocket vertically. Two 8-foot 3030-S beam extrusions from 80/20 Inc. will be attached to the test stand and supported by aluminum angles. The 80/20 beams are more than I need for this application but I plan to use them later during final assembly to help with alignment of the skin to the frame. The rocket will be mounted 6 inches away from the beam using 3 x 6 x 1/4 inch square tubes as spacers. The thrust load will be reacted through two 1 x 1 x 1/8 inch angles that tie into the injector manifold at the top of the engine and then to the vertical beam.
Robert also talks about modifying a CDI ignition system to provide feedback before opening the igniter valves, this guarantees 100% the sparkplug of the igniter will be working when the propellant is passed through it, thus allowing the main engine to be ignited.
One feature I wanted onboard was feedback from the CDI ignition module to verify it is working before opening the igniter valves. However, the CDI power supply comes from an isolated offboard source so I had to design an optoisolated current monitor circuit that ties into the onboard data system
I have just personally ordered a CDI ignition system for my own project so it will be interesting to see how this works out.
Robert provides an update on his recent round of static tests and rehearsals before the firing of his 250lbf liquid rocket engine in its rocket configuration.
What I found of most interest was the below,
LOX fill technique – During the previous tests, I was unable to completely fill the LOX tank. For these tests, I used a modified fill technique which involved closing the LOX vent valve first, waiting a few seconds, then closing the LOX fill valve. This allows the 20 psi or so in the dewar to compress the ullage in the tank and get some more liquid in. I also added some temporary foam insulation to the tank and fill lines. As a result, the LOX tank pressurized in less than a second instead of the almost two seconds previously.
Always good to read these little hints and tips to put in the back of the mind for future use!
The update is full of bullet points so it is easier to post the link.