Does Orbital Still Have The Right Stuff?
Orbital’s private launch may show whether NASA made right call, Orlando Sentinel
“In the past four years, a different Orbital rocket failed on two separate NASA missions. Jeff Foust, editor of The Space Review, said Orbital needs a success to stake a bigger claim on the space-launch market. “If they have problems with [these Antares test flights] … it starts to raise the question on whether they can make this whole thing work,” Foust said, adding that it’s a test of whether a midsized company such as Orbital can survive in an evolving space economy that features both upstart tourism ventures and heavyweight defense companies such as Lockheed Martin.”
This thing looks real small compared to the Falcon 9. How do these things match up?
The energy density of the solid upper stage is a lot higher (although doesn’t run for anywhere near as long) and the lower stage runs for longer. An ‘apples for apples’ comparison is hard but it is billed to have broadly the same performance-to-LEO as Falcon-9 v.1.0
It turns out that they will carry the same amount of internal cargo to ISS. From what I have read. It is much smaller. Everybody has been complaining about foreign content, but NASA is saying that they are required to do so and they are saying it is a good thing. I thought State had diplomacy.
By the way, if a story is not put up here you want to comment on,go to Space Ref. A lot more articles and if you are signed in here,you will be there too. Like F9 1st stage will try to land on water next flight,Elon says and he expects failure. He says he will start the engine to slow it down to reenter, then restart to to land. So computers, Radar,Lidar. Will they be able to pick up the Ocean through the spray and steam? In free fall looks like they would need thrusters also, to keep it straight. Fly back next year. New Dragon out soon. Coming down on land. Lots of good practice for crew landings. Going to have some nice large windows. It will carry a larger payload. I think they will use it on the next flight. Will finally see a landing. On land yet. Last I heard they will use parachutes and only use rockets to set it down softly. All this from a news conference yesterday. The notice is on Space Ref, but not here. Nobody commenting there, I hope you will join me.
I also saw these pretty awesome stories-
SpaceX’s Merlin 1D Engine Achieves Flight Qualification
“The Merlin 1D has a vacuum thrust-to-weight ratio exceeding 150, the best of any liquid rocket engine in history. This enhanced design makes the Merlin 1D the most efficient booster engine ever built…”
http://spaceref.biz/2013/03…
XCOR Propulsion Milestone on Lynx Suborbital Vehicle
“XCOR Aerospace today announced a first in aviation and space history, the firing of a full piston pump-powered rocket engine. This breakthrough is the foundation for fully reusable spacecraft that can fly multiple times per day, every day.”
http://spaceref.biz/2013/03…
The XCOR piston engine pump has a significant advantage in cost and can generate very high pressures, but is heavier than a comparable turbopump, particularly for larger engines with high flow rates.
I’m not sure that trust-to-weight ratio is the sole determinate of “efficiency”. Isp is perhaps more important.
The best metric for launchers is “system cost”. It doesn’t matter what your ISP is if you can’t make a profit.
RD-170 is staged combustion ( more complex? more expensive? ) so it has a higher Isp.
James:
The Merlin 1d trumps the RD-170 in the weight to thrust department (150 to 1). Simplicity and reliability will make up for the rest of that higher Isp.
tinker
Agreed, but I’d like to see the cost, and propellant weight versus turbo machinery weight for both solutions.
Is staged combustion worth the extra cost & complexity?
I’d trade more copies of a far cheaper engine on a slightly bigger stage (tanks, fuel, and LOX are relatively cheap) over a smaller stage but with a much more expensive engine.
If the vehicle is reusable the base engine cost is much less important and the higher ISP would reduce the fuel burn rate and increase payload. Maintenance/turnaround cost for the engine and the reusable vehicle as a whole would be critical of course; the high performance of the SSME could not make up for the cost of fabricating the ET, rebuilding the SRBs and maintaining the TPS.
Agreed in principle, but only for the sake of redundancy. If you lose one engine out of several, you can possibly continue (or at least not lose everything), as the SpaceX engine-out experience showed. But if you lose one engine and one was all you had, things can get sticky.
However, if, somehow, you had a 100% (or nearly so) reliable engine, then the simplicity argument wins and a single big one would get my vote. I suspect that the savings on spares alone would make for a significant cost advantage for the single-engine design.
S13:
Don’t worry about the Falcon first stage free falling after it slows down. Take an empty paper towel roll and wedge a weight into one end. Toss it into the air and you’ll see that it stabilizes every time it falls. The Falcon stage will do the same thing because it’s much heavier at the engine end. As for a water landing for the first Falcon stage, GPS will be accurate enough. They don’t want to reuse that stage, just recover it. Even damaged it will provide SpaceX with invaluable data that would otherwise be completely lost.
SpaceX is really pushing ahead on development, putting (IMHO) ‘traditional’ space hardware providers to shame. Instead of dangling ‘possibilities’ in front of NASA, then telling them it’s vapor without funding, it seems like SpaceX is willing to take the initiative (Grasshopper, Raptor) and inviting NASA along for the ride. No wonder the folks at NASA love them. NASA couldn’t get the ‘major players’ to do the kind of research SpaceX is doing for love or money. Not only that but the ‘check signers’ in Washington are not only not getting this, they’re being downright obstructionist toward SpaceX!
Go figure.
tinker
Tinker do you know if they are considering eventually landing the Falcon booster on a mobile platform, or is that too difficult due to rolling deck, and/or too cost prohibitive? I realize they might have the capability to bring it back to the coastline, however I’m not sure how the FAA and others would feel about allowing a powered rocket to head towards instead of away from populated areas. Of course the range safety devices could still be used, but there would be less decision time available compared to when the momentum is moving away from the coastline.
Based on a talk I just heard at SpaceX in Hawthorne, their intent is for both the first stage and the dragon capsule to land at the launch site, in traditional sci-fi fashion. The factory tour was fascinating; in particular I was impressed with the laminate composite operation to build the rocket bodies, and the titanium/stainless 3D printers used in the manufacture of the rocket motors.
Do you think they can turn it around in space by gimbaling or will have to use thrusters? GPS is enough to give altitude? That will work. Elon said it was ballistic. Did not say anything about your straight up launch. Maybe a lot will be RC. It might stabilize tail first,but Soyuz comes down rotating and on its side,flat.
S13,
After separation I’m not sure why it would matter what attitude it has in free fall. Once it starts hitting atmosphere on the way down it will orient itself bottom- (most massive) end down, like Tinker says.
I suggest that there’s one more requirement, though — you’d want it to be designed to aerodynamically stabilize in atmosphere, to minimize any wobble, pogo, cross-wind rotation and/or translation, and/or vibration. And there’s no additional energy input required. It could be a simple as four small “fins” on the sides at the top (think of an upside-down Redstone rocket).
Using thrusters adds considerably more mass, etc,. and requires additional excess fuel dump over your landing area, which you want to avoid if you want to land somewhere useful. Also, dumped fuel adds to your operating costs.
I think the fins could fixed in place throughout the entire mission, including launch, without any adverse effects, therefore no fin deployment mechanism would be required. That’s just my take on things.
Steve
The orientation is important because the thrust has to be in the line of flight for the burns. Also the the vertical has to be in the range of the gimbals. The fins might work. The air flow over the engines is not smooth. A simple altimeter and gyros and timer might work. Get it close and drop it in. I guess the only way we will know what happens is through Tweets. I sure miss the days when NASA covered everything and we were there. NASA will use a well landing ship,rather than a carrier next year. Pull it in over a cradle and pump the water out.
Saturn13,
I think we might perhaps be envisioning this a little differently. I see things as follows:
The Falcon 9 first stage separates at around 100 km altitude. (That altitude also happens to be the Kármán line, which some people regard as the border between Earth’s atmosphere and space, but it’s not an official designation).
Atmospheric effects on a reentering object actually start higher up than that, at about 115-120 km. So, at stage I separation we’re already in a position for the empty stage I to reorient itself to a vertical attitude aerodynamically as gravity pulls it down, no thrust required. The bottom-heavy plus fins-at-top configuration should accomplish that easily and fairly quickly.
At some lower altitude parachutes get added into the picture, which would further stabilize the expended stage’s vertical attitude and slow it down (I’m assuming a standard drogue ‘chute followed by one or more main ‘chutes.) Deployment of the parachutes would be by pressure-altitude-controlled pyros, with ground controller’s manual backup, a well-proven system.
Then, at a still lower altitude, as close to the ground as possible, they’ll use the last of their fuel to further reduce the vertical velocity and soft land the expended stage, still vertical, on its landing legs.
The only major new challenge in this is precision landing at a chosen location. Left to itself, where the stage lands would be a function of where it was in its orbit at separation, which, in theory, they can pick, since the second stage plus Dragon can continue in a free fall orbit until the point where you want to do the injection trajectory burn. Alternatively, they may let it go one or more extra orbits and do systems checks before committing to injection.
The one remaining problem is affecting minor translations to land exactly where you want, not just close. And that is where your thrusters and GPS would come into it. These positional fine-tuning adjustments would need to be done before the landing burn; in fact, they’d have to be done while the vertical velocity was above some critical value, so as not to mess up the vertical attitude stability.
That’s how I see the stage I recovery happening. Does it sound reasonable, or did you have something different in mind?
Steve
Tinker, Dragon2
Dragon2 is just a lander not a spacecraft.
With Elon talking about the new dragon 2, I started thinking again about your second stage Leo taxi, which got me wondering if the dragon two will be more shaped like a cylinder than a cone. Mr. C said all missions start with a lander. Well I thought that the design goal of cargo dragon was dragon rider, but now I’m not so sure? I think that Spacex dragon/cargo dragon/dragon2/dragon rider is really just a lander and taxi’s to space will be done by the second stage. Since you are going to recover the second stage anyway why not have people in it and have it fly all the way to a station and unload it’s cargo then fly home? Is dropping the second stage critical to having enough fuel to do a crew mission to ISS or a low flying Leo Bigelow habitat?
Just seems to me that an earth to Leo taxi should be two recoverable pieces not three to save a buck in operation cost. And dragon rider is just a interim step to a lander and a two stage space taxi.
The crew compartment only separates in an emergency, other wise the second stage goes along for the ride.
Just thinking through another one of your good ideas Tinker.
Elon did say that dragon 2 will have more room?
If all missions start with a lander seems Elon has the jump on everybody for robot and human missions to mars, moon and any other firm rock in the solar system
I’m more focused on Orbital’s traditional business model than on its technology. Even if the tech works, I’m not certain, given the company’s Congressional testimony, that it will be able to compete in the low-cost, fixed-price environment that SpaceX seems to be fostering. Not that this can’t be fixed, but I will be interested in seeing exactly what Orbital–which is more accustomed to a cost-plus environment–has to charge to get a pound or a kilo to LEO in order to survive.
Orbital is quite familiar with fixed-price
They expressed concern in congressional testimony that the SAA/COTS, fixed-price approach might not allow them to continue competing. Their words, not mine.
Intresting… Do you know when this testimony was given? I haven’t been able to find it. Thanks!
I watched in on CSPAN last year. I would have to spend time Googling it. Orbital would probably give you a copy of the transcript if you contacted them.
Orbital has plenty of experience in fixed-price contracts. About 21% of its revenue comes from commercial contracts (geocomm, primarily) which are fixed-price. A number of its NASA contracts are also fixed-price through vehicles such as the RSDO catalog. In fact, Orbital started the low-cost, fixed price trend that SpaceX is following. The question is can Orbital retain that model and the agility it had been known for – or is it transforming into the big aerospace model it once challenged?
To LEO –
Antares: 5,000 kg
Falcon 9 v1.1: 13,150 kg w/engine out (SpX number), 16,000 kg without (NASA number)
Here’s an interesting article: http://rocket-propulsion.in…
Thank you for that James; it was a good read.
It seems that the retired RD-170 was the baseline for almost all of the big Russian rocket engines in use today. It’s performance is comparable to that of the F-1, but the design would appear to be much easier to build and maintain — multiple smaller components instead of single very large ones; and the use of multifunctional components was a significant step forward.
The 20-times reusability feature is something I wasn’t aware of. I wonder how it has worked out for the various designs spawned from the 170.
Space questions
Steve,
How does dragon know how much to fire it’s engines before it does a soft earth landing. In the past when we have had landers land on mars we know the exact mass of the lander and it’s payload before landing so that the proper thrust can be applied to make a perfect soft landing. Well?? With frequent future flights the down payloads could be drastically different from flight to flight and you have said that the vehicle has to fire it’s thrusters at the very last second at the perfect amount of thrust to not crash land. So seems to me unlike the payload in an airplane that dragon has to know it’s exact mass every time. Is there a way for a dragon to robotically figure out it’s weight/mass each time????? Like using gps to figure it rate of fail versus wind resistance or something????
Or is the payload weight difference small enough to not be critical????
The dragon2 said how much do I throttle these last minute super dracos Lol
George,
Assuming that they haven’t invented something new, basically, Dragon knows it’s approximate mass (initial fueled mass minus burned fuel is one way; running inertial calculations during flight is another) and its rate of descent (radar altimeter, with pressure altimeter backup), so its computer can calculate a deceleration burn (rates and times). Once the burn starts, it monitors the change in rate of descent in real time, compares it to the calculated burn, and fine tunes the thrust as needed to match the calculated burn.
There’s one aspect of this I’m not sure about, and that’s excess fuel. Ideally, you’d want to land with your tanks empty just as you touch down (a safety measure in case of problems). Will Dragon, and/or any other vertical landing system be required to dump excess fuel (in excess of what it calculates it needs for landing plus a margin)? There are arguments for and against, and a lot depends on where you’re landing (you don’t want to be dumping fuel on a city or someones farm every week).
Landing on Earth is easier than landing on Mars. Even though our gravity is higher, using parachutes in our atmosphere gains us a lot of deceleration and better control — everything happens slower here, so there’s more time to adjust things. The almost zero atmosphere on Mars makes parachutes much less effective.
That’s the simplified, tried and true answer.
Sensors might include radar altimetry, laser altimetry, precision GPS, inertial platforms, accelerometers.
Amazed that every thread always seems to turn into a
discussion of Falcon/Dragon – by the same posters, and those same posters
always seem to disparage everything other than Space-X.
DO NOT QUESTION THE ALMIGHTY SPACEX!!!
– stinker
Steve:I don’t see a reply button, so I will add this. The first stage will be set up like the second. They will need all axis control. Fire the thrusters to rotate in place. Fire the engine to slow down. Control attitude with thrusters until ocean is picked up.Then it is like Grasshopper to land. That is the first flight. They will know how long the first burn is, so they know were it will land. I guess they will have telemetry so they can correct if they are headed for Mexico.
With flyback they will reverse in space. Fire engines as needed to get to launch pad. Reverse. Burn for the right speed and location.Land like Grasshopper. I think that thrusters will be enough. If not a small parachute would keep it straight.
As for your safety question. They will have a ballistic aim point off shore. When tracking shows it is on target, safety will give the ok. It can not go onshore,even if it blew up. Once Grasshopper takes over the sideways motion is so slow that no parts could go very far to be a danger.