Friday, May 18, 2012

SpaceX Readies Falcon 9 Rocket---No, Not That One

The excitement of waiting to see a launch can do strange things to me. Tonight, it can make me fall asleep at 6 PM, instead of my more usual midnight to one AM, so I can get sleep before the upcoming SpaceX CTOS-2+ launch. It can make me so excited that I woke back up after just three of the five hours I'd hoped to spend asleep. And, apparently, it can spur me to blog for the first time in...a while. Anyway, I'm probably going to be sharing several pictures of Falcon 9 and Dragon tonight, but I have some special ones first. THESE ARE NOT COTS-2+. This is the next Falcon 9, whose first and second stages are already in storage at a site near the SpaceX launch complex at LC-40 (specifically an old Delta facility, Hangar AO). There's only room for one rocket at a time in the main SpaceX integration hangar, and right now COTS-2+ is filling it (well, not right now, since it's rolled out to the pad, but it has dibs :) ). Hangar AO serves as a surge facility, letting them store hardware that won't fit in the main hangar until it's actually needed or there's room for it.
If all goes well tonight, in the next few weeks this hardware will be sitting where the COTS-2+ rocket was a few days ago, being readied for the next launch. Similarly, another Dragon is being completed at SpaceX's factory at Hawethorne. If tonight's launch and the coming mission goes well, that flight could become CRS-1, the first operational commercial launch to ISS. Otherwise, it becomes COTS-3, a third demo flight to prove that they can fix whatever the forces of Murphy's law might throw at them on COTS-2+. As I hear, that would be planned for August or September--driven by the time to finish preparing the Dragon and for a hole in the ISS's packed visiting vehicle schedule.

For SpaceX, the next critical goal after flying Dragon to ISS is to demonstrate that they can achieve the kind of flight rate needed to satisfy both NASA's CRS cargo contracts and the contracts they have to launch satellites for research, communications, and navigation. To do this, they have to step up their game in terms of launch rate and production. Having this hardware at the Cape already is one small step in that direction.

Tuesday, February 28, 2012

Status Update, February 2012

Well, it's been a while. No excuses, I'm not going to lie to a blog basically no one but me reads, but I've just had other things on my mind. What sort of things? Well, here's a basic rundown:

1) Work: Since late January, I've been working as a co-op for GE Aviation here in Cincinnati, in a Quality Control position at their Erlanger Distribution Center in Erlanger, KY. Despite the name, it's actually right next to the Cincinnati airport (CVG), mostly because the Cincinnati airport (for long and complex reasons I do not fully comprehend) is located in Kentucky. It's been pretty cool, chief among the attractions being that it's a workplace where I can sit in the break room at lunch and see airplanes powered by the engines I'm chasing parts for take off and land just down the hill and across the airport boundary fence. I'm not allowed to take my own pictures, so this is roughly the view I have, except further back and slightly higher up so I can see the runways.

Anyway, it's been a great experience so far, and I'm looking forward to continuing there for the rest of the summer.

2) Aerodesign Team: As with the last two years, I've once again been a member of the University of Dayton Aerodesign team. This year, I was leader of the Missions Group, responsible for all things rules and payload. I've also been pitching in a lot on the 60-page competition report, which we finally finished and submitted last week. As part of getting the report ready, we were pushing hard for a first flight so we'd have flight data for the paper. Unfortunately, the fuselage manufacturing team was delayed due to the long holiday break, and I was seriously worried we weren't going to fly before submitting the report. This was troubling because Dr Altman, our advisor, stated he thinks this paper may be one of the best we've submitted, and didn't want to see our performance in the scores at competition compromised by penalties for lack of flight data. Leslie, the team captain, managed to pull together the team and work a miracle at the 11th hour, and they got a prototype kludged together from the wings, tail, landing gear, and tail truss from this year's aircraft, combined with a fuselage stolen borrowed from a past aircraft.

It wasn't pretty, but it worked and we got the flight data we needed for the report. However, I think we definitely have a lesson to take away from this for next year: if the break is as long again as it was this year, at least a few members of the team must come back early to begin construction and ensure that sufficient buffer is allowed to absorb any slips and still allow flight before the paper is due. This plane flew two weeks ago, and again this week, generating some useful results about the lifting capacity of the wings and facilitated some messing with motor setup and props, but a more complete aircraft using the proper fuselage, improved wings and tail, and generally fully embodying this year's design is hopefully to be completed this week. I'm planning on going up later this week to help with that assembly and catch up on what I've been missing being away from campus.

3) Extracurriculars: In addition to all this, I've also had projects of my own. Chief among them lately has been Eyes Turned Skyward, an alternate history timeline I've been co-writing and publishing roughly weekly on the forums. You may notice it's been running for a while, but this is the first I've felt up to talking about it on Engineer in Progress, largely because I'm aware it's probably full of amateurish technical mistakes and generally bad writing. Never-the-less, I'm pleased to say we've managed to reach nearly 27,000 views and over 400 comments on the 24 posts so far in the timeline, and we've received the Atomic Rockets Seal of Approval from Winchell Chung of the Atomic Rockets reference site, meaning we stand alongside works like Mass Effect 2, Orbiter, and the Beyond Apollo and Rocketpunk Manifesto blogs. Ah well. If we cannot be seen from afar, it is because we stand amid the ankles of giants. A lot of the reason I haven't been blogging much is that when I have been writing, it's been for this.
Official Atomic Rockets Seal of Approval, as received by Eye Turned Skyward.
Beyond working on Eyes, I've also been working on one final project. For the past year or so, I've been talking a good deal with Winchell Chung, and because of this he came to me for advice on preparing a poster showing off the jaw-dropping mesh he's done of the Polaris, from the "Tom Corbett, Space Cadet" series. He often uses the Polaris as an example, and he created a pretty detailed model of the Polaris as part of this. For this, he was kind enough to send me a copy of the final poster, which is currently hanging on the wall next to my desk. It's amazing, and the image below really can't quite do it justice.

Polaris Poster Thumbnail. See here to buy, or here for more on the Polaris.
In addition to the advice I provided on some details of the poster, I've also been providing some thoughts about revisions to the Polaris, including a rather substantial redesign of her pods. I provided a basic concept based on the role envisioned (basically to transit between the ship and stations while in orbit or as an inspection pod--kind of a useless role, but it's the best way we could find to rationalize the pods from the series). Compare the pod shown in the poster above to the draft concept I sent Winchell, and the amazing model he made based on that. I can't link them in here, but check the album out. It's been a fun little project. It's been particularly cool because Winchell's site is one of the main things that made me realize back in high school that rocket science was something I could actually do and made me decide that I did want to go down the aerospace engineering path that's taken me to where I am today. In a way, helping out with this has felt like paying that back.

Anyway, this ended up being a longer post than I thought it would be, so I'm tying it up here. Long story short, I've been doing some stuff that's kept me away from blogging for a while. I'm not sure that'll change anytime soon, but...I'll try to make time.

Tuesday, October 25, 2011

Ideas That Might Hold Water (Or at Least LOX)

Any regular readers I may once have had may notice it's been a bit sparse around here lately. In short, it's been because between classes, my OSGC research, and other projects, this blog has fallen down my list of priorities a bit. I'm planning to go into how that's been going in another post later, but the main reason for this post is that I got re-interested in an old idea of mine today and I thought it'd be worth writing up for Engineer in Progress. So let's talk about the SpaceX Dragon, and how I think it could be converted into a reusable fuel tanker for a fuel depot architecture.

I've very interested in the potential of depots in exploration architectures. It allows reusable orbit-to orbit spacecraft to be used for transits to the Moon or Mars, and allows missions that would require superheavy-class launch vehicles without depots to be staged with nothing more than existing or planned launchers like SpaceX's Falcon Heavy. For instance, on an Apollo lunar mission, the total hardware mass was only around 30 metric tons, but the total initial mass delivered to Earth orbit was 127 metric tons or so. This means that with a depot system for storage and transfer of cryogenic propellants, an Apollo-class mission could have been undertaken with 4 launches of a 30 ton vehicle. The lesson here is interesting particularly because of the capabilities of the Falcon Heavy and Falcon 9 Block II rockets (roughly 50 and 15 tons respectively) and their relatively low costs compared with past vehicles.

However, the need to fill such a depot requires a vehicle to serve the depot, a tanker. This vehicle will have to be launched as payload on a rocket, then be maneuvered to dock with depot and offload propellant. This creates two options. The first is a dumb stage, a tank that is inject to an orbit close to the depot, then grappled by a reusable space-only tug and moved to the depot. This makes the tank light, cheap, and ultimately disposable. The other option is a stage that's smart enough to fly itself, eliminating the need for the tug. However, this makes the stage an automated logistics spacecraft and thus expensive. Thus, if possible, it seems that such as "smart" spacecraft should be reused if possible. 

In thinking about reuse of a "smart" tanker, I was inspired by the concepts for using modified Delta IV upper stages as depot components like the image shown above. It seemed like fairing over the tank structure could create a capsule-like shape. Covering this with a thermal protective system could allow a ballistic entry into the atmosphere for reuse. However, this require a lot of modifications, since the Delta IV 5-meter upper stage shown as a depot component in that image isn't intended for long-term use or reuse,. Thus, adding proper maneuvering control and thermal protection might be very challenging. Turning a lightweight tank stage into a capsule might be a bridge too far: too hard, too heavy, too expensive.

However, what about turning an existing capsule into a tanker? SpaceX's Dragon had always been my mental image of the final product due to the steep sidewalls that would be dictated by the Delta IV stage design. However, since liquid oxygen has a density of about 1.2 tons per cubic meter, a tank filling the payload margin for a Dragon would also roughly equal the pressurized volume. With a 16 ton-to-orbit Falcon 9 Block II and the 4.5 ton mass cited for Dragon on Wikipedia and in some SpaceX materials, this leaves room for 11.5 tons of LOX, which would have a volume of about 9.5 cubic meters. this fits nicely in the 10 cubic meters of pressurized volume on-board a Dragon. thus, it's possible that the only work needed to turn Dragon into a Dragon LOX Tanker would be to add insulation and an internal tank inside what is currently the pressure hull, and add systems to fill this tank on the ground and empty it into the depot on-orbit. The primary structure could remain largely unchanged, as could the Draco thrusters and the capsule's control systems. Dragon's thermal protective system has already been designed to be capable of multiple flight, so I think it's possible that after factoring in all the costs, this could be a competitive alternative to expendable "dumb tanks" both per-flight and on the more critical $/kg scale.
Dragon Pressure vessel being integrated with bulkheads for the un-pressurized hardware section containing thrusters and other equipment. In a Dragon Tanker, this pressure volume would contain the LOX tank.
As to why I suggest a single-fluid tank (LOX only) instead of carrying both a fuel and LOX, there's a couple of reasons. First, while the idea could work with two tanks (one for LOX, one for fuel), kerosene and methane are both less dense than LOX (70% and 37% as dense respectively) so a Dragon spacecraft carrying a full 10 cubic meters of mixed kerosene/LOX or methane'LOX might not be taking full advantage of the launch vehicle's capabilities, Liquid hydrogen is so much less dense (only 6% the density of LOX!) that it's not even worth thinking about. (On a side note, this low density is why despite the fact that only 16% of the mass of a hydrolox rocket's propellant is hydrogen, the hydrogen tank is usually several times the volume of the LOX tank. See the Space Shuttle external tank, the Saturn IV-B stage used in Apollo, or the Delta IV upper stages used in the depot shown above.) This means I don't think the added complexity justifies the gains. 

This is especially true in my mind in light of the fact that for almost all liquid rockets, LOX makes up far more of the mass than does the other fuel. For instance, 100 tons of fuels for a kerolox rocket would consist of only 30 tons of kerosene, while a similar mass of hydrogen/LOX fuels would be 16 tons of hydrogen. A depot storing LOX could serve to "top up" stages launched carrying fuel only whether they burned kerolox, methalox, or hydrolox, while being substantially less complex due to the need to only handle and store one fluid. 
Anyway, in short, Dragon is an existing multi-role vehicle that I think might adapt well to serving as a cheap, reusable LOX tanker as part of a depot-based exploration architecture. I think it'd be an interesting trade study to compare in more detail the cost per kg of fuel of a "dumb" expendable tank system versus a modified Dragon Tanker like I've described above, but I don't know that the data do do so is available publicly.

Monday, September 12, 2011

How I Spent My Summer Vacation (By Rob Davidoff, Age 20)

It has recently come to my attention that, despite the evidence to the contrary evidence of the post rate here at Engineer in Progress, I am in fact not dead. In fact, with the start of the school year, I’ve actually had time to do things, even! With that, I thought it would be worth bringing everyone up to date on my summer and what I’ve managed to get checked off of the To-Do List of All Dooms.

In this post, I’d like to talk a bit about what I did this summer (a topic that makes me feel like I’m making a presentation in second grade). As you may recall, I spent this summer as a test engineering intern at Ferno-Washington in Wilmington, OH. I meant most of the summer to write a post describing what exactly what that meant, what it involved, and what I felt I was learning, but unfortunately between my mom’s health issues, the commute to work, and other complications, I never had the time. So let’s start things with that.

"So what is test engineering?", I hear you ask (unless you're part of the 50% of my traffic that's just here for the pictures, in which case you'll be more interested in the diagram of the BA-2100 in another post planned for later this week). I'm glad you asked. Basically, test engineering is involved with the testing required to test various design concepts during engineering development, and then to validate design prototypes against internal and external standards to ensure that the final product can do what it needs to do. If design engineering is about making solutions to problems, test engineering is involved in picking the best solutions and making sure the solutions work as intended under varied conditions.

This meant a lot of dealing with paperwork, and a lot of dealing with standards. In doing this, I came to some realizations about the two. This summer at Ferno, my major responsibilities were processing test requests from design engineers, carrying out and documenting the testing, then preparing formal reports about the test, which meant I had a lot of experience with paperwork. In my ten weeks at Ferno, I participated in closing out about 30 tests, which included both ones I performed in addition to ones that had been performed prior to my arrival, but which had my boss had not had time to document himself. In both cases, while preparing the formal test reports, I depended extensively on photographic and written documentation of the events of the test. And the reports themselves had value: for many reports, we would refer during the test planning stages to setup descriptions of similar tests in the past to ensure that our methods were consistent with the past setups.

Standards also played a major role in my summer work at Ferno. In testing, the question that was always asked about a new test request was the purpose of the test--what was intended to be learned. Was it to compare several design solutions and find the "best"? Was it intended to determine whether a prototype was capable of performing as desired? In all these cases, standards played a critical role in planning the test and evaluating the test results. These standards could be regulatory, part of the standards that Ferno's products had to meet to be certified for use in the demanding conditions emergency equipment may encounter, or they could be internal standards to ensure that the product also provides users with the quality they rely on. In dealing with these standards in testing, I came to better appreciate the need to have such standards. Without a defined standard to test to, a test really isn't informative. The standards themselves must be meaningful (testing to proof or ultimate loads or simulating field conditions), but a test done to a meaningful standard is far more meaningful than one without a defined standard.

All in all, I really enjoyed my time at Ferno. I was lucky that most of my co-workers were friendly and easy to work with, and I feel like I made a valuable contribution during my time there. When I arrived, the test report backlog had grown to more than thirty reports, on the day I left it had been reduced to six, none more than a week removed from the date of test completion. I feel like I learned a lot more about the purpose of testing in engineering and what makes a test valuable, and I look forward to carrying these lessons on with me, both to the Aerodesign team this school year and on to other areas of my professional career. So, yeah, that's what I did this summer. I have more to say about what I've been up to since my last day at Ferno, but since this post is already pretty long, I'll leave it for another time.

Wednesday, June 29, 2011

Free Time? What Free Time?

It's been busy for me, between work and some health issues for my mom, so I haven't had as much time to blog as I might have liked. That's as far as I'll go towards making excuses for my lack of posts the last week or two. However, that's not to say I haven't been working on stuff, just not much and not for very long at a time, and I haven't had any time beyond those work periods to write about them. On that catch-up note, here's an entire project of mine I've yet to even have the chance to talk about here.

About two weeks ago, I was contacted by someone who wanted some help rendering something. You may have heard of the Nautilus-X spacecraft proposal, a design for a long-term reusable orbit-to-orbit vehicle, built in multiple launches using ISS operational experience. The most striking feature for many people is the centrifuge ring, which is spun to create the illusion of gravity. This tends to excite space fans, since centrifuges have this whole air of sci-fi about them, and yet are still plausible, except for all the messy little engineering details like making the plumbing and wiring work across a rotating interface or the effects on maneuvering of essentially having a 30 ton gyroscope mounted to your ship.
Nautilus-X, front perspective view showing centrifuge ring
Nautilus's centrifuge is interesting because it proposes to use inflatable structures for much of the ring. It consists of a rigid hub, connected by a rigid passage tube to a rigid ring section. The ring itself is a mix of such rigid sections linked by inflatable sections (the other two rigid sections are connected by extending trusses to the hub, and serve to help support the ring in spin). Compacted, it's a very tight package, and makes good use of the rigid components where rigid is of benefit and inflatable where inflatable is best. On-orbit, the trusses would extend the ring sections, then the ring would be inflated and fitted out with habitat equipment: sleep stations, communal living areas, perhaps a sickbay or other equipment where gravity would pay off. The idea is interesting, if a bit of what Robert Zubrin would call a "Battlestar," an over-complicated slightly over-built spacecraft, but it's a big dream and I like those. The images of a test centrifuge attached to the ISS as a tech demo especially appeal to me. I've often lamented the loss of the funding for the Centrifuge Accomadations Module, and the lack of really good data on the reaction of the human body to varying gravity levels (including prolonged sub-Earth levels, like a Mars colony might have) and the rotation rates possible before biology and gravity gradients become an issue. With these two pieces of data, it'd actually be possible to design a 2001-style station or a spacecraft like the Discovery (or indeed Nautilus) with some kind of artificial gravity centrifuge.

Demo Centrifuge at ISS
The person who contacted me asked if I might be willing to try to render a conceptual cutaway of the interior of the ring. I used to spend days in middle school doodling diagrams of spacecraft and drawing scale floor plans of them, so this appealed to me, especially since it'd be a nice chance to press my modeling chops. It seemed like a fun thing to try and do--design a possible interior in a relatively small-diameter rotating centrifuge. I should be clear that neither he nor I has any real idea of the internal layout of the Nautilus, I'm not sure one exists at this time, despite all the nifty images of the ISS demo module. Thus, the following is only my best guesses, and as much informed by the design of boats and mobile homes as by valid spacecraft design principles. I hope Winchell Chung can forgive the transgression the previous sentence represents, but it's about the best I can do for the moment. Engineer in progress, it says so in the title.

Anyway, so to start, I needed to establish the physical parameters of the ring. It has been stated in presentations of the concept to have a diameter of 60 feet, and from the image above, scaling from the core (stated in another slide to have a width of 6.5 m), the ring's minor exterior radius looks to be about 4 m or so. Taking into account inflatable walls with a thickness of 16 inches, on the order of Bigelow's designs, this produces an interior diameter of about 134" (Yes, Imperial units. Deal with it. I did.). This gives a volume of around 425 cubic meters, about right for 6 people's occupation for up to two years. It's worth noting that combined with timing this animation of Nautilus (yielding 10 seconds per spin, or 6 RPM), the ship is basically designed to yield Martian gravity: 1/3 Earth gravity.

Cross-sections of Ring
To create the interior of this ring, I defined a flat floor as shown above, based on a minimum overhead of 6 feet. I show a centerline passage of 36" and a passage going past a partitioned room (shown with 36" bed), with 30" of floor space, and some extra elbow room. I then broke down the ring into rooms using these arrangements, and created the design below in Adobe Inventor. The "roof" level is a 78" ceiling: enough to give some head room even for tall people like myself, but not quite towering. With all the area under the floor available for use by utilities, I think that when I get around to modeling a ceiling, it'll be much more of narrow enclosed (?) utility run along the middle than the illustrated flat surface at 78" above the floor, a duct as opposed to a drop ceiling.
Attempt at Nautilus Floor Plan
Click  Image for Full Size
After some refinements and modifications based on discussion with the person who requested the work, I was satisfied enough to begin rendering the ring in Inventor. I rendered each portion (cabins, heads, the mess/galley area, the gym, stowage, the lab and medical bays) separately, so I could assemble them in any order, and so that changes to any on of duplicated rooms like the heads or the cabins would be reflected in all of them with the click of a mouse the next time I opened the assembly. Some rendered animation of the model are below (my first attempt at it with Inventor and it kind of shows--note for future: floors and background should contrast more). I'm hoping to refine both the model and my method of showing it off a bit more, but I'm pretty happy with the start of it. 

View One (Click to play)

View Two (Click to play)

Tuesday, June 14, 2011

Good News and Bad News

So, as the title suggests, I have some good news, and I have some bad news that it'll be bringing with it. The good news is that as I mentioned last post, my summer suddenly became a bit busier than I was worried it might end up. After a lot of job searching, I accepted an offer of a summer position with Ferno-Washington Inc. of Wilmington, Ohio.

Wednesday, June 8, 2011

Imagined Images and Reality

So, you may already heard this (curse my sudden lack of free time!), but the STS-134/International Space Station images are finally in. The image NASA's been promoting the heck out of (and rightfully so, I think) is below, showing the station from the port side, with the shuttle and the station's truss and modules both very visible.

Click image for mondo big version
For those interested, many others from the same astounding  set can be found on the site here. Personally, I think I have enough new backgrounds to last for months if not years. (Also see the video here, for some more amazing content.).

This is truly an amazing and historic moment, but looking at it and thinking about why it is, it reminded me of an image I posted a while back here on Engineer in Progress. No, not Kieth McNeills's amazing model images of what an STS-133 flyaround might have looked like (now with side-by-side comparisons with the real thing on NASAspaceflight's forums here). Something earlier.

Is it the STS-71 Mir image, taken in a similar fashion to the ISS imagery sequence?

No, it's not. It comes from even slightly before that. See below:

That's not the ISS there. That's an artist's conception of the American Space Station Freedom, from the mid-80s to the early-90s, the station which morphed into the core of the American portion of the station. So the Shuttle-docking-to-station image has legs. Why? Because this is what the Shuttle was about, about building and servicing a large space outpost, where various types of science could be performed, from life sciences, materials experiments, astronomy (early SSF proposals included an attached telescope observatory), and technology demonstrations for revolutionary new space hardware (in it's day, they were looking at stuff like solar thermal power generation).

Basically, only in the last few years has the ISS has actually started to do that. The AMS-02 instrument is amazing, but it's only now at the end that it's finally flown. Proposals are circulating to test BEO technologies like VASIMR, inflatible habitats or closed-cycle life support systems on ISS (the ISS water-recycling system is sort of part of that, and that's been going for a few years now, I guess.). And now, finally, after almost 20 years, it's finally happening. That's what I see when I look at the images of Endeavor docked to ISS: the culmination of a 20-year dream.

What's next? Where does spaceflight go from here? I wish I knew. I wish anyone knew--the whole situation with the SLS (Space Launch System, a congressionally-mandated new heavy lift vehicle) is so convoluted, politically-and-emotionally-charged and multi-polar I don't think I can adequately state what the situation is, but it's there. There are also the multitude of dreams offered up by Bigelow, SpaceX, XCOR, Armadillo, Masten, Altius, and many other commercial space companies. In 20 years, which of these dreams will be a reality, and will it take all 20 to make it happen? I wish for as many of the former as possible, and hope not the latter on any. But we'll just have to see. I just wish the space program of the next decade could amaze me and my generation in ways the space program of the last 50 occasionally has amazed past generations, and continues to amaze those of us who care to research it. That's all I want to say, just go back up and enjoy all the links.