Just wanted to post a short note letting people know that we’ve now selected two interns for this summer, and therefore will no longer be taking applications for this summer. However, due to a surprising amount of interest in the possibility of internships for this Fall, we’ve decided to go ahead and offer two internship positions for the fall. We don’t yet have precise dates, but these would likely start sometime in August, and run through sometime in November, depending on when people are available. We will be releasing further information on these Fall internships in the coming days, including the deadline for submitting applications, when we’ll be running phone interviews, and when we’ll announce our internship selection.
April 2008 already. That means we have been around for four years and we’re still kicking. More importantly, we are still progressing. The coming year looks like it will be exciting. But before I get to what we are planning for next several months, let’s go back a few months to set the stage.
Back in June we started flight testing of XA-0.1. We found a lot of issues with the hardware and just how much of a pain multiple engines can be. I have developed a lot more respect for Russian rockets that use a lot of engines. For nearly six months we tried getting a controlled flight and we found lots of little subtle things that could make a big difference. In December this attempt at flight occurred:
XA-0.1 R.I.P.
After the crash we started taking a very close look at everything, and I mean everything. Not just the technical details, but our processes, staffing, and everything else. One of the things that we decided to change was the balance between analysis and build it, try it. We have always thought that NASA and the prime contractors concentrated too much on the analysis. We still think they over-analyze things, but we have shifted towards spending more time making sure things have a chance of working before we build it and try it. One of the things we did was set up a more accurate vehicle model and 6DoF simulator for getting a better handle on control laws and system interactions.
Once we set our course adjustments into motion we took another look at how to make XA-0.2 even better. We turned down the pressures required in the engines and tanks, and turned up the engine thrust. We found a new tank fabricator, and designed new engines. The XA-0.2 design lost weight and gained performance. Currently we are waiting for delivery of various long lead time components (like tanks!).
We are not just sitting around waiting for parts to come in. We have found a number of ways to improve various sub-systems and decided that we want to verify those on a flight vehicle before XA-0.2 is ready for them. So, let me introduce XA-0.1B
As you can tell, there are still some details missing, but enough of the important things for fit up are on there and we are cutting and welding the steel frame as I write this. And yes steel frame. It is strong and easy to work with. For XA-0.1B we do not care much about flight time or delta-v, we care about moments of inertia and the ability to control orientation and position.
To sum up, we have a lot of work ahead of us - building and testing XA-0.1B, testing a new engine, and building and testing XA-0.2.
Masten Space Systems will be out in force at Space Access ‘08 in Phoenix later this week. Almost everyone involved with the company will be there, and a number of us will be presenting:
at 4:50 pm on Friday, Dave Masten will be giving the general Masten Space Systems update.
at 8 pm on Friday, the Space Propellant Depots Panel will be led by Jon Goff
at 8 pm on Thursday, our un-indicted co-conspirator Ian Kluft will be on the panel Paths to Rocket Piloting
at 4 pm on Friday, I (Ben Brockert) will be giving a brief presentation on Students for the Exploration and Development
of Space
and, at 4:20 on Thursday, Ian Kluft will be talking about the Stratofox Aerospace Tracking Team.
It looks like it will be an interesting conference. Say hello if you’re there and you read this blog.
We’ll have an update here about MSS’s progress and future direction after we get back.
If you’re not bored with the igniter stuff yet, I think you will be by the end of this video. The igniter is not the only thing we’re working on, but I spent a day running it through qualification last week and it’s something I can share right now. It currently has 632 firings and 1578 seconds of cumulative fire time, and has shown the ability to operate correctly under a wide variety of operating conditions. It has officially passed its qualification testing and is ready to be used on the 750lb thrust engine.
Over the weekend I learned LabVIEW and wrote a virtual instrument to do data acquisition on the igniter cart, and calibrated the pressure transducers earlier this week. Today we ran the igniter three more times, so we can start dialing in the correct nozzle throat diameter and orifice sizes. As expected, the igniter chamber pressure is bit more than double the final desired value. Here are the promised Mach diamond photos. Still not as good as they should be, but you can kind of see the first glowing spot in the flames.
Run 2:
Run 3:
I haven’t insulated the pipes yet, and the humidity today in Mojave is an unusually high 32%. Even with an ambient temperature of over 70F (294 kelvin), uninsulated LOX pipes (at about -300F [90 kelvin]) grow frost:
I’m going to go drill out the nozzle now.
Edit: Drilled it out, ran it 9 more times, got a better photo:
The igniter is up to 14 runs and 35 seconds of flame time.
Masten Space Systems is looking for two technical interns for the summer of 2008. Working out of our Mojave, California facilities, you would be directly involved with a variety of interesting projects and would gain experience in working for an innovative space company. You must be a US national, and available for approximately three months from mid-May or early June through late August.
Projects you would be working on include testing state-of-the-art rocket engines, flight testing vertical take off/vertical landing rocket vehicles, fabricating and testing components for future projects, and evaluating new hardware concepts.
We are looking for people who have direct experience building, troubleshooting, and testing actual devices: people who know how to use tools and are not afraid to get their hands dirty. You do not have to have experience on a liquid fueled rocket engine, but we want people who have hardware experience, perhaps working on a car or plane, flying an amateur rocket project, or building a robot.
Specific applicable skills include:
Mechanical assembly, especially of pressurized systems
Machine shop skills, working with tools to make things out of metal or composites
The ability to run an experiment, record data, and figure out what the data means
Installing and wiring an electrical system, possibly including radio controls or computer programming
Experience with Labview, Solidworks, and/or Matlab.
You don’t have to have all those skills, but having a variety is a plus. You must have a willingness to learn, pay attention to detail, be able to take initiative, and be open to working on a variety of different projects and experiences.
In addition, we have ongoing programs that involve rocket propulsion, mechanism design, electrical engineering, or wireless telemetry. If you have experience in one of those areas, we may assign you your own project where you will be responsible for the design and execution of a component or subsystem.
If you are interested in a fun summer, working on big rockets and unique vehicles, please send a resume to internships [at] masten-space.com. You are also welcome to send photos and/or a description of a past project you have worked on.
Masten Space Systems is a Mojave-based aerospace R&D startup that is working to create reliable and reusable rocket vehicles and components. Current company focus is on regeneratively cooled bipropellant rocket propulsion and fully reusable rocket-powered vertical takeoff and landing vehicles.
Hello, I’m Ben Brockert, the new technician and fabricator at Masten Space Systems. I started with MSS about three weeks ago. I’m originally from Iowa, where I was involved with the Iowa State Space Society and SEDS-USA. One of my major projects since I started here has been rebuilding the igniter testing cart.
The old cart had no liquid oxygen (LOX) handling capability, so we rebuilt the cart with a LOX tank in an insulated box (the LOX Box). It was built with room for expansion, so that we can easily adapt the cart for RCS engine testing in the future. The fuel side is pressurized with nitrogen and the LOX side is pressurized with helium, so this revision of the cart uses brazed joints on the LOX side to minimize leaks. Helium can get past normal joint sealing methods, the same way a sealed helium balloon will deflate after a few days. The new cart also has better containment of the test article for safety purposes.
Today we finished the last of the plumbing and ran the new igniter for the new engines. Though the new engines are 50% larger, the igniter itself is smaller and lighter than the old igniter. This represents the first hardware testing of the new engines. The LOX vaporizes in the plumbing upstream of the igniter, so the igniter runs on gaseous oxygen (GOX) and isopropyl alcohol (IPA), both at 400PSI. The flame is about six inches long and has a number of Mach diamonds in it. We’ll get photos showing them in the next week.
This is the first run. For scale, the extruded aluminum “X”s that the igniter is mounted on are one inch square.
Here is the second run. Since the igniter body has a significantly smaller thermal mass than the old design, we’ll have to be careful not to overtemp it when running it outside the engine. In a normal engine cycle, it would only need to run half as long, and would be actively cooled. It wouldn’t normally glow.
It’s the beginning of a new year, and there are many changes afoot at MSS, so I figured it was about time for a bit of an update. A lot of people were curious about what direction we would end up taking after we damaged our vehicle last month, so I wanted to discuss some of our plans for this year.
MSS Now Hiring
One of the biggest changes that we’re undergoing at the moment is an effort to augment the core team here at MSS. We haven’t had any real changes to our core team since early 2005, but situations change over time, and we’ve been recognizing the need to expand and diversify our skillset as a team. Basically, we came to the conclusion early last year that there are a couple of areas that we really need to have someone in-house with solid expertise in, particularly Guidance, Navigation and Control. We’ve updated our careers page with more details, but I’d like to go into some of the reasoning for why we’re looking to fill some of these positions.
GN&C Engineer(This position has been filled)
Even though we’ve been working with outside groups to provide us with expertise in this area, we’ve long since come to the conclusion that having someone in-house who has a good understanding of controls engineering is very important. Having someone with real experience in that area is critical to properly specifying and designing actuators and other subsystems. A lot of the control systems related challenges we’ve had to fight through over the past year and a half came from not knowing what to expect, “failure to overcommunicate” when it came to specifications, and just the general learning curve of figuring out what data was important and how to actually verify that things were performing the way you expect them to. Quite frankly, the basic rocket propulsion part of our vehicle has been the easy part. Now, we’ve actually learned a lot of these things by now (the hard way), but we’d like to have someone on board who can work with us when we sit down to do a new vehicle, and make some models to predict the kind of specifications we’ll need for throttle valves, gimbal response etc. We’d also like to be able to have someone on board who knows what they’re doing controls-wise so we can make modifications to our flight code as we do flight testing, to speed up the iteration cycle. GN&C really ends up being the heart and soul of a VTVL rocket system, and not having anyone in-house who even “speaks the language” is a situation we’d like to change. If anyone reading this happens to either have experience in Multiple Input, Multiple Output control systems (particularly in an aerospace or aviation environment), or to know someone who does, they can find more information about the specifics of what we’re looking for here.
Senior Engineer/Project Manager
Several months back, we had a good friend (and competitor) of ours drop by for a visit while he was in the area. One of the things he brought up got me thinking a lot about the various approaches there are to building an engineering team. Our friend’s company pretty much only hires people with 10+ years worth of experience in aerospace engineering. His philosophy was that sure you have to pay them a lot more, but you’re getting a solid engineer, a known quantity, someone you can depend on. There’s some truth to his philosophy, and his company has been making good progress. On the other side of the spectrum, we have some other friends whose company doesn’t have a single person who had previously done professional rocketry. I’m not even sure if a single one of them had ever fired a liquid rocket before they started their company. But they’ve also been very successful over the years, and have earned a good reputation in the industry. We’re probably a lot closer to the latter than the former. I’m not sure of this, but as far as the entrepreneurial space launch community goes, we may have the youngest engineering team overall. Dave’s the only one who works here full-time that’s older than 30. I’m the only one who ever worked for an aerospace company before this job (and that was just as a contract proposal writer/patent writer), though Pierce and Dave had both built and flown peroxide monopropellant amateur rockets.
All told, both ends of the spectrum have drawbacks as well as benefits. The more I’ve thought about this, the more I’ve come to the conclusion that like many things in life, the best option is probably somewhere between the two extremes. I had a chance recently to meet some of the members of the propulsion team for another major alt.space company, and I think they do a really good job of this. While they have some very experienced industry veterans heading up the department, the younger engineers outnumber them about 3 to 1. The younger engineers get a great mentoring environment, while adding a lot of enthusiasm, new ideas and approaches, and excitement to the mix. Having at least some experienced engineers on board also helps make it so the younger engineers don’t have to learn all of their lessons the hard way. Before I had met that propulsion team, I had already been leaning towards the belief that the best way to organize an engineering group is to have a balance of some more experienced engineers along with a larger number of younger engineers, but now I’m pretty much convinced.
Especially since we’re now starting into some more complicated projects for some of our customers, we’ve decided that as part of the restructuring of our team, we’d like to bring on a Senior Engineer/Project Manager. Someone who’s been in industry a bit longer (though not necessarily the launch vehicle industry–there are several other hardware related industries that would also provide useful experience), who may have a broader depth of knowledge, and who has more experience with managing complex projects than any of us do. You can find more details about the specifics we’re looking for here.
Office Manager/Accountant
On the business operations side of things, we’ve decided to bring on an office manager to take some of the weight off of Dave, so he can focus more on the engineering side of things. Trying to be the President, CEO, “Speaker to Regulators”, Accountant, Office Manager, Ground Controls Programmer, Pilot, Network Engineer and Janitor all at the same time is a little bit more than you should leave on any one person’s plate for too long. More details on that position can be found here.
Technician/Fabricator
The last position we’re currently looking to fill is for a technician/fabricator. Ian’s been doing a lot of our fabrication work, but we’d like to bring on some additional help whose sole focus is this area. Basically we’re looking for someone with an attention to detail and who has good shop skills and the willingness to learn new skills and techniques. Prior experience in a machine shop, or as a welder/fabricator, an auto or airplane mechanic, or other related technical backgrounds is strongly desired. More details here.
Technical Plans: XVT-750LIT-1 and XA-0.2
On the technical side, we thought long and hard after XA-0.1 was damaged last month. Our first inclination was to just patch her back up and get her back in action. It would’ve only taken 1-2 weeks to get back into shape, but the more we thought of it, the more we agreed that it was time to move on. One of the issues that has been plaguing us with XA-0.1 for over a year was that due to a “failure to overcommunicate” we selected a throttle valve concept and hinge actuation system that didn’t have adequate response characteristics for controlling a multi-engine vehicle like ours. The response characteristics would’ve been adequate for a single engine vehicle like some of the ones Armadillo has made, but that would’ve required redesigning both the engine and the vehicle as a whole (and would led away from our long-term path), so we tried to just see if we could make the system work in spite of the actuators. However, after this last flight, we realized we had finally reached a point where it no longer made sense to keep trying to force XA-0.1 to work, and that instead it would be better to take all of the lessons learned and move on to a new vehicle.
XA-0.2
For the new vehicle we narrowed down the options to three main alternative approaches:
Build a subscale vehicle using smaller engines with much faster actuators and a more symmetrical vehicle arrangement with an inline tank configuration.
Build another XA-0.1 scale vehicle, but with some improvements such as an inline tank configuration, engines closer to the centerline, wider baseline landing gear, and much faster throttle and gimbal response.
Finish XA-0.2 but with upgraded engines, throttle valves, and hinge actuators.
We decided to go with the third option for several reasons. First off, bigger vehicles that are more symmetrical are easier to control than smaller vehicles. The much higher inertial matrices make the vehicle less sensitive to perturbations, which greatly relaxes the requirements for response time on the valves and gimbals. The fact that XA-0.2 has the engines closer to the inside, and the landing gear further out doesn’t hurt either. Second, we had already built a lot of the hardware for XA-0.2 by the time we stopped work due to the tanks problem, and we had already put the design through an external design review, so we had at least some validation from an experienced team, that our concept and approach was on the right track. Third, we have a customer that wants to use XA-0.2 this year, and if we built another vehicle first, we might not be able to deliver in time. Fourth, XA-0.2 was the only option that actually moves us forward towards our eventual goal of fielding XA-1.0.
There are a couple of changes in the works already for XA-0.2 compared to the original design we were building for the X-Prize Cup. First off, we’re going with a centralized engine computer for this vehicle. We realized that with the vehicle we had, we had lots of computers, but no real redundancy. If any of the engine computers (or the vehicle computers) had died, we would’ve lost the vehicle anyway. We’ll still probably have valve and hinge control boards as well as a sensor muxer board down on the individual engine modules, but all the main smarts will be run off of the same PC-104 stack that runs the vehicle Onboard Flight Management System (that controls the shutoff valves, vent valves, ground ops, and range safety). The other big change is that we’re going to rework the entire engine design.
XVT-750LIT
One of the quirks of the original XA-0.2 design was that since we were using the original 500lbf engines, the vehicle would only have enough thrust to take off with a half-load of propellant. That would’ve still given us about 120-150s worth of flight time, but in order to get enough thrust to take off with a full propellant load we were going to need either a fifth engine, or to upthrust all of the engines (what we were then calling XA-0.2B). Since we were going to need to redesign the valves and actuators anyway, and since there were still one or two remaining squawks with the engine design that we wanted to fix, we decided that now would be a good time to upthrust the engine, and roll in all the lessons learned from our previous engines.
We’re in the process of releasing the prototype for production. Our performance goals are to achieve a 50% increase in thrust compared to our previous engines (ie 750lbf) at a much lower chamber pressure (250psi vs. 550psi), all without increasing the weight by more than 50%. We’ll take a slight Isp hit due to the lower pressure, but it will also make our tanks a lot easier. In fact, it brings our tanks down to a similar pressure range to what have been done by Armadillo and Paragon. And this time around we’re optimizing the expansion ratio for lower altitude flights, since our near-term projects are mostly low-altitude missions. What this means is that in spite of having a lower peak Isp, if we hit our targets we should still have almost as good of a mission-averaged Isp for long hovering missions (such as the Lunar Lander Challenge). The engine design also features a more compact igniter style, a new chamber/igniter interface, and at least as of this moment is only predicted to weigh less than a pound more than our existing engines. The design is a scaled version of our previous engine, so we have pretty high expectations of it working well for us. Here’s what the engine looks like (minus external plumbing):
We need to get the trailer rehabilitated before we can start testing, but we’ll probably be doing that while this new design is out for machining. We’ll post more details as we have them.
Contracts and Other News
We recently finished sending off the final report for our first commercial contract, which involved doing a design review on a 6-axis Solid Rocket Test Stand designed and built by the Florida Institute of Technology (in conjunction with Space Florida). This stand is to allow students and other groups to test solid motors up to 10klbf, with a really good DAQ system. We’re talking forces and torques at high enough resolution to measure any sort of combustion instability issue you could think of. We look forward to working with these guys again in the future.
We also have another major project and some licensing agreements in the works that we can hopefully say more about in the near future.
The vehicle lifted off and appeared to be under control - not very good control mind you - but the control system was trying to do the right things at the right time for a bit. It climbed to about 20′ AGL when I concluded that the control wasn’t right and shut down the engines. The vehicle then fell, either hitting the tether limit or the vehicle landing gear clipping the edge of the pad. The structure broke off between the electronics bay and the rest of the vehicle. The tanks and propulsion section hit the ground, broke an engine mounting structure and broke one of the landing gear. The electronics bay was still swinging from the tether. Here is what the scene looked like as the dust cloud moved out of the way.
Note the fire on the left. This was a small bit of isopropyl alcohol that got spit out when the propellant tanks were vented.
The safety systems were flawless. The vehicle was completely depressurized and safe to approach in a matter of seconds. We of course waited minutes to make absolutely sure, but that was the other safety systems working well.
We are considering various options for moving forward. In a way the death of XA-0.1 is a relief, as it had some issues. The two options that are favored right now are either finishing XA-0.2 or building another low performance vehicle from the surviving parts. XA-0.2 is already designed and being built, but I think it is a higher risk for being damaged in flight test. Another low performance vehicle could be built fairly quickly, fix some of the known issues that we had with XA-0.1, but we’d still have to deal with the issues that we couldn’t fix.
Wow. It has been over a month since we’ve posted anything. In the last month or so we have been regrouping and re-prioritizing. We have done several more tethered flight tests, been through a few iterations of controls code, started doing hardware in the loop simulations with the control computer, and made some more progress on building XA-0.2.
The problem with not posting updates for a while is that a lot of folks start guessing about what is going on, and the guesses are diverging rapidly from reality. So here is what all has happened since the last post.
We had outside experts do a technical review of the XA-0.2 design. The outcome was that it wasn’t perfect but it was workable and should be competitive for the NG-LLC. We got really good feedback on how to make it even better. The really good thing was that most of the concerns raised were things that we were already aware of. So, if we can get some good tanks XA-0.2 should be a good flyer. Oh, and one of the reviewers said he could fly the vehicle with one engine out using his control code, it is ugly, but it can be done.
Speaking of control code - a few people have suggested that we made a mistake outsourcing our control code. First - none of us at MSS know controls theory beyond the simplest classical control algorithms. Now we could have hired someone to be our controls engineer - and we’d have only one person who had any clue. By outsourcing we can get a team of competent engineers and therefore if one person is sick, injured, or whatever we aren’t stuck. All in all, Frontier has been pretty good. There were some issues with specifications and vehicle characterization, and that led to doing a bunch of tests where things just could not work. As we worked through the issues, Frontier has been responsive and the latest revision looks good in ground tests and basic simulation.
On to flight testing - we have had the latest control code version for about a month now, but XA-0.1 is our first prototype, so it has a few more maintenance issues than a more mature vehicle would have. We have spent the last month or so hammering on every single squawk recorded over the last several tests, and several more squawks discovered while fixing the others. I thought we would do a flight test last week, but there were a few more issues than we expected. Hopefully, we can get back to flight testing this week.
I should note that we are downright abusive with rocket engines. Over 2 hours of run-time and 700 ignitions over the past two plus years on one design. The engines have run in nice weather, rain, sleet, and dust storms with hurricane force winds. Ambient temperatures during runs have ranged from 27 deg F to over 110 deg F. All of the engines now on the vehicle have been damaged in testing, re-worked and put back into operation, some of the engines more than once. These engines do require a bit more maintenance than we like, but that is as much a matter that they are prototypes not production versions. We hope to be in a position to do a revision of the engines Real Soon(tm).
The past month has been a very busy one at Masten Space Systems. As Ian mentioned in a previous post, the timeline for getting XA-0.2 built, debugged, and flying in time for the X-Prize is fairly tight. While we designed in a little bit of slack to deal with minor delays, we unfortunately ran into a more serious delay that is going to preclude us from competing in the X-Prize Cup this year. We were informed late last week by the company spinning and welding the propellant tanks for XA-0.2, that the tanks had failed their hydrotest by a very large margin. The tanks failed right on the weld at less than half of the designed operating pressure, and it appears that a poor weld with incomplete penetration was the culprit.
Unfortunately by this time, this particular supplier was also nearly three weeks behind schedule, so there isn’t any feasible way we can have a backup plan ready to go in time for the competition.
We’ve started work on another set of tanks, using a different set of manufacturers, to allow us to complete XA-0.2 for further development testing.
We have been making an effort to post more pictures and media lately, but have not been putting up a whole lot of technical info to explain what some of the stuff is, and where we are in our progress.
So, I intend to rectify that with this post.
The basic situation is as follows: We are currently tether-testing XA-0.1 and in parallel, we are building XA-0.2.
The status with XA-0.1 is that we have all basic systems working, and have narrowed down our lack of ability to attain stable flight to the control system. We have identified what we think is the major culprit and have made a change to correct it. We will be testing that shortly, if not today.
At the risk of sounding like another NewSpace company making claims about progress based on apparently failed tests, I will say that XA 0.1 has already accomplished most of it’s goals. It is easy to forget (and we do it, too) that XA 0.1 was only designed to test several basic things, among which are:
1.) The integration of our engine systems with a third party control system.
2.) The integration of our engines with our TVC system.
3.) The design of a vehicle propellant and pressurant system.
4.) The control of vehicle propellant and pressurant systems.
4.) Pilot interface systems.
5.) Vehicle based operations, as opposed to test-stand based operations.
6.) Fundamental architecture validation.
7.) Tethered hover.
It has, thusfar, succeed in all except #7. Of course, #7 is a pretty important one and one that we would all like to see - and soon, but it is important to remember that this vehicle has accomplished the majority of what it was designed for already. Those lessons and validations have been applied to the design and development of XA-0.2.
As we make changes to the control system, we expect to accomplish #7 within the next several weeks. Providing we can do so, we are still on track for XA-0.2 being ready for the X-prize cup this year.
Regarding XA-0.2, we are on schedule with it’s construction. By the time we’re done with all of the flight testing currently planned for XA-0.1, XA-0.2 will be sufficiently assembled to allow us to swap over the propulsion and controls systems with minimal delays.
In brief, XA-0.2 is a natural progression from XA-0.1. Utilizing a lightweight frame, larger propellant tanks, and lightweight pressurization system it is a much higher performance vehicle. The dry weight of XA-0.2 is within 100 lbs of XA-0.1, but is capable of 5x the propellant load (resulting in a 100% propellant load mass ratio of 2.5) . It uses legacy electronics and propulsion hardware to facilitate a rapid transition from XA-0.1 to XA-0.2 flight testing. Among other details, it has a more favorable inertia matrix allowing easier control as compared to it’s predecessor. This combined with the legacy hardware gives us confidence in our ability to get XA-0.2 operational within a short period of time following initial success of XA-0.1.
The XA-0.2 vehicle will be capable of approximately a 50% propellant load with legacy propulsion hardware. Further evolution of the vehicle past X-prize cup will include a 50% increase in engine thrust in order to utilize 100% propellant load for increased delta-v. This vehicle architecture will proceed through the next several iterations of the XA line, further expanding the flight and performance envelope until the architecture is no longer viable. At this point I should define architecture to mean a basic vehicle platform. Expanding the performance envelope within a given architecture would mean upgrading components without overhauling or re-designing the entire vehicle. An example would be, with XA-0.2, we can upgrade the propellant tank diameter without changing any fundamental components. This allows us to increase delta-v on an already functional vehicle without a complete re-design. While the XA-0.2 architecture is capable of enough delta-v to reach nearly 100 km, it lacks provisions for other components (specifically aerodynamic surfaces, retractable landing gear) necessary to do high altitude, high velocity flights.
If we can avoid any serious setbacks in our schedule (late vendors, accidents, etc), we will have XA-0.2 ready for competition at the X-prize cup this year. I’m not going to release our development schedule, but the time alloted for the various tasks necessary is not overly aggressive and I think gives us a high chance of success. Of course, if one of the companies manufacturing a key component decides to take 6 weeks instead of 2, for example, it will impede us significantly - however, we are being proactive about these issues and are doing everything we can to prevent delays.
For all of you who have been wondering what’s going on - and why things are so quiet as of late…
We have two things going on. The first is that our vehicle’s frame was breaking, badly. We decided to take the time and tear it apart and replace a lot of the aluminum members with steel. The 80-20 bolted together extrusion we used was just a poor choice and it could not handle the loads the tether was subjecting it to.
So we replaced a lot of the bolted AL with welded steel. Should be much better now.
On the more rocket-related side, we have been pouring over the data we gathered in the last few weeks trying to figure out why it won’t really fly. We think we have it now - and are taking steps to correct it. I has to do with how the control system is interfacing with the pilot.
So, as soon as we get that changed and fully tested, we will be back at it. We are hoping for good things.
We discovered that it helps if your hinges are moving the way you think they are moving them. 180* out tends to cause big problems - like the vehicle inexplicably flying off the stand and stuff.
So after fixing that, we were able to do this:
Lit all 4 engines, and it just sat there. Like you think it should.
Had to shut it down before liftoff because of the IPA fire you can see. Small leak on one of the engines that we are fixing right now.
I hope everyone had a safe and happy 4th of july. We tried to make fireworks, so to speak - but had a small IPA leak that caused us to scrub.
A brief update about where we are - we are starting to gather data on the control system in order to figure out why it’s not flying the vehicle. In the process, we noticed that one of our LOX valves was out of calibration, causing late starts on one of the engines.
We fixed that, and hoped to test yesterday but were stopped by the IPA leak. Now that we are into the holiday weekend - progress will slow down slightly. Not sure if I will have enough staff on hand today to test safely.
Well, yesterday (Friday) wrapped up our first week of tether testing. No, we aren’t flying yet (it just so happens no one in our company is named superman.) We are however, making steady progress. I would like to list the top 10 things WE think are significant victories.
Fundamental Victories:
1.) We haven’t destroyed our vehicle. Gotta start somewhere, right? Those first few unrestrained tests had a significant pucker factor. (did we size the tether right, etc)
2.) We haven’t had any engine failures. These are rocket engines - and this is always in the back of my mind. We haven’t had a credible system failure in a LONG time (and we rectified the cause of it) but it still makes me nervous.
3.) We have reliable ignition (when WE actually use the system right). Testing 4 engines at a time rapidly stacks up the number of attempted ignition events, and will expose bugs or inconstancies in those systems very quickly.
4.) All 4 engines are capable of working together, without any feed system coupling issues or anything else. The 4 engine architecture with simple feed system is not fundamentally flawed.
Less basic:
5.) We worked out some timing issues to allow a consistent 4 engine ignition.
6.) The engines are throttling as commanded
7.) The hinges are moving as commanded
8.) The vehicle is fundamentally stable. What I mean by this is we now have it to the point where merely igniting the engines does not result in a loss of control. Now, without any command inputs - it will just sit there cooking.
9.) The ACS system is fundamentally correct. It’s sense of direction and what to do about it correlates with the real world.
10.) We are back to testing and development - not troubleshooting and fabrication. The Test - Analyze - Adjust - Test cycle is one that we are pretty good at, and is so much more mentally stimulating than leak checking 2 billion AN fittings. I expect rapid progress up until our next impasse.
I have more test video from Friday, but it really just looks like the other videos. We light the engines, and it kinda shuffles around and falls off our stand. The big thing on Friday was the ACS actually over corrected for a rotation about the Y axis and actively de-hovered the vehicle, so to speak. The negative X engine started to dip early into the hover (and when I say hover, I am talking 10ths of seconds, so nothing “real”), and it throttled it up way too much, tipping the vehicle over about the Y axis and pushing the positive X engine down. An induced loss of control. At that point it hit the tether and it was all over.
So we’ve got some control system tuning to do it looks like, possibly coupled with some engine throttle tuning to make sure we aren’t giving more thrust than asked for. Monday will start another week and another phase in our vehicle testing. I’d call it phase three.
Phase One: Fundamental vehicle troubleshooting and functionality testing
Phase Two: Reliable engine ignition and fundamental stability tuning
Phase Three: Flight control system tuning and flight stability tuning
So, here’s hoping. On the plus side - almost all the parts of XA-0.2 have now been ordered, and assuming we can get this vehicle flying properly in the next two months, we are on schedule for the LLC this year.
We have realized two things in our testing thusfar. The problems are related.
1.) Our engines don’t start at the same time. Duh. Welcome to the real world.
2.) Because they don’t start at the same time, the vehicle experiences various moments during the startup phase. If the startup thrust is too high, those moments are sufficient to rotate the vehicle about it’s opposing landing gear - setting up a disturbance that is to large for the ACS system to be able to recover from as the opposing engine lights.
So, What we needed to do is lower the startup throttle in order to prevent the moments from overcoming the intertia of the vehicle on startup. We did some testing today and got a pretty good result. The vehicle stayed level on the stand at startup.
Something else also happened. Upon reviewing the video, we noticed that half the landing gear were fully extended after ignition. This means that they fell off the stand (not surprising as it is a fall away stand) and the vehicle was balanced perfectly horizontal on two feet. We then had an engine flameout ( an expected condition that I will explain later) and the vehicle then lost it to that side.
What does this mean? Well - it’s a little premature and I think we will need more testing to verify - but I think it was hovering. You can see for yourself in the slo-mo video what you think. It is clearly balanced on only half the landing gear.
We pulled the Vehicle back today to make a few changes pertaining to the tether mount. After abusing it the last two days, I wasn’t too happy with it - and neither was anyone else. We decided to replace it with a much stronger welded steel peice.
So we thrashed all day to take care of that as well as a few annoying leaks and extraneous parts. No tests today, but a few shots of us in the shop.
Anyone need tickets to the Gun show?
I know these probably look staged - but we literally had everyone crawling all over the thing all day (Well except Dave and I, I sat at the welder welding things that people handed me). That’s how much effort it takes to make a few basic changes and get it back ready for testing. These are really complex systems and it takes a lot of man hours to get things changed and make sure they are right.
