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SpaceshipOne's Control Problem Fixed
Baldrson writes "Wired News reports that Rutan's team says they have gotten to the bottom of the June 21 flight anomalies that affected the first SpaceShipOne sub-orbital flight: 1) A control surface actuator had run against a stop limiting its movement, and 2) Wind shear caused the 90-degree roll shortly after rocket ignition. Rutan also said with the problems now identified, the next time SpaceShipOne flies, it will be to win the prize."
So Carmack and the Armadillo gang are out of the running?
When you're designing a space ship thats primary goal is to get it only to the edges of space, wind shear is one of your top priorities.
MY spaceship wasn't affected by wind shear.
The article says that the problems were caused by:
"the actuator delayed moving one of the ship's flaps because it "had run against a stop," limiting its movement."
Isn't the WHOLE purpose of the stop to limit movement? or was the stop jarred loose and was stopping movement when it wasn't supposed to ?
Rutan's plan to have 3 flights within 2 weeks is a good idea. That way they have an even better chance of winning the prize. It's something I never thought of before.
JasonBlogs
According to Scaled's Careers page, "We are sorry but Scaled is unable to hire Summer interns or Co-op students." I didn't think any high tech companies could cope without co-ops and interns!
-- SYS 64738 --
No, not first, but it gets list somewhere I'm shure. At least for any craft that has to deal with atmosphere.
Me first thing I worry about is the Huge laser cannons and force shields. That and a seat for cute blue space chick.
Maybe this is why NASA hasn't called back.
Mycroft
https://signup.leagueoflegends.com/?ref=4c3ed6600b6ea
"1) A control surface actuator had run against a stop limiting its movement, and 2) Wind shear caused the 90-degree roll shortly after rocket ignition. Rutan also said with the problems now identified, the next time SpaceShipOne flies, it will be to win the prize."
So I guess it's:
1. Fix control surface actuator
2. Fix wind shear problem
3. Profit!
His luggage lands in Africa somewhere...
Web Sig: Eddy Currents
I reckon Scaled Composites could almost make more than the value of the X-Prize if they offered those two empty seats for sale. It's almost worth starting a fake ebay auction just to see what price is reached!
Nothing is really guarenteed to be perfect. The fact that there are factors that are beyond our control and completely unpredictable means that there is always a chance that something will go wrong. Fixing it and trying to make sure it doesn't go wrong again is all fine and everything, but there is always that probability factor that we cannot detect, calculate, or control.
I am just quite glad that they had the backup system, because that is what prevented a catastrophy. If there is a x% chance that the primary system will fail, and x% that the backup will fail, combined it makes the chances of a catastrophy much lower.
I believe that if we are going to be successful at a private space race, or even any other high-risk things (Even lacking risk to human life), then redundancy and backup is definitely critical. If a few failed heat tiles can destroy a space craft and kill people, and there is no contingency plan for failed heat tiles, that is a problem. If a computer miscalculation in Metric vs English measurements can completely throw off a multibillion-dollar space probe, and there is no way to recover when the error is first detected and has not yet caused problems, then that is just not right.
I look forward to seeing if they win the prize, and I applaud them for having contingencies. If more systems had contigencies for the most critical failures, we'd possibly be much further ahead in various technologies. Let's see how this space race goes.
@Whee
The trip they made on the 21st of June did not count at all for the X-Prize. It did go past 100 km, but it did not have the additional weight necessary to simulate two passengers. Basically it was just another test flight. What was significant about it in a historical perspective is that this is the first time a privately owned company has put a man in space. Thus, they yet to even do the first of two flights required by the X-Prize.
NASA, on some level, is really an organization for several major and minor companies, why would it be ruled out of the prize?
Will commercializing spaceflight be a step forward for space research? Why is it that when companies step into public domain scientific fields the results are inevitably viagra when there is still no cure for cancer, aids... etc. Public grants and public institutions (Nations and Universities) are still the bedrock for pure scientifc research. I only see economic and superficial consumerism inspired by the x-prize.
What do you think?
You should have been there for the first flight. I'm amazed that they got it off at all. The winds overnight were 40+ MPH on the ground (blew over 4 of the 7 porta-potties in the campground area on the airport grounds). They calmed down for the 6:30AM launch, but it was easy to see from the contrails behind the aircraft above that there was still a lot of wind up there.
Best of luck to all involved, Scaled Composites and others. I would love to see the Information Age give way to the Space Age and humanity crawl from the cradle of Earth.
High-speed Road Trip (18.000KPH)
I am a pilot, albeit an ordinary private pilot and not a spaceship pilot. I began flying in the 1970s around the time that "wind shear" first started to be considered as the possible cause of certain kinds of accidents. Although the phenomenon is real, for a while it became somewhat notorious as one of those "catch all" explanations that get hauled out when someone can't really figure out what happened. So when I hear it blamed in a conclusory way for something weird, without a good explanation for why it should apply, I get skeptical.
The deal with wind shear is this. Ordinarily, airplanes move within moving masses of air and get carried along by them. This is no big deal except that it affects navigation (e.g., even though your nose is pointed north, you might really be tracking northeast because you are within a mass of air moving from west to east). Moving masses of air don't ordinarly affect the airplane in an "aerodynamic" sense because what matters is how the plane is moving relative to that mass of air, not relative to the ground. Wind shear occurs because there are often distinct boundaries between different masses of air that are moving in different directions or at different speeds. Hitting a wind shear boundary can be an issue because due to inertia (or momentum, whatever you prefer to call it), the plane does not instantly make the transition to the new conditions, so its situation changes temporarily relative to the air. But it's only scary when the extent of the change is greater than the aerodynamic limits for your airplane and your present attitude.
For example, if you are flying at just five knots above stall speed, and you hit a boundary that has an abrupt ten knot difference in the wrong direction, it can pull the rug out from under you. But if you're flying at normal cruising speed, that same difference just causes a little turbulence. So to have a critical problem with wind shear you need both factors -- being near one of your aerodynamic limits (stall speed, red line, whatever) PLUS hitting a boundary that emphasizes the change in air movement in the WRONG direction for that limit.
So the reason I am skeptical is that Rutan gives no explanation for how exactly wind shear caused the loss of control. Was the ship being operated near its stall speed? Was the wind shear differential totally huge? Was the ship in a weird attitude (high bank angle or something) that reduced its tolerance to changes in airspeed? And is there any meteorologic evidence of any big wind shear conditions at that place and time? Otherwise, it is just wishful thinking that he has an explanation for this?
Between the private space-flight, a entire space station (built internationally no less), and the possibility of a space elevator, humankind really is heading for the stars!
This just an altitude record. Not a space flight! There's only so much you can do in suborbital. If you just want to get up there to launch a satellite, then you might as well simply use a big missile, and put the effort into recovering the lower stages.
When they manage to get to 3 times that altitude, then its time to be impressed.
NASA is ruled out because that's what it says in the rules. This is to encourage private spaceflight. The main reason for that is efficiency. NASA can't screw in a light bulb for under $1M.
Yes, Paul Allen paid a lot for this. He paid $20M. But as Rutan (I believe Dick) said at the SSOne launch, Paul Allen could have bought a flight to the ISS with that money (Tito paid $10M), but instead he bought an entire space program. So others will be able to go to space (for short periods) for a whole lot less than they would have before.
Spending $20M on this ship is a huge advance for space flight in my book. You can't get a Gulfstream jet for that, and its development cost was amortized across multiple airframes. Also, a Gulfstream doesn't go to space.
No he wasn't travelling near his top speed. In fact it was just at the start of the climb.
So I would tend to believe the wind shear explanation:
At the start of the climb, the "plane" (more like a winged rocket, really) had high thrust but low speed, went vertical and hit wind shear. Each wing was going through a different wing mass, and this spun the plane 90 degrees. After that, the plane was going fast enough that wind shear didn't matter.
Incidentally, I was there watching with another 20,000+ people. It was impressive, seeing this white streak shooting vertically.
Your explanation sounds great, but, you are using the wrong frame of reference. You are considering classic wind shear at low level/low speed accident scenarios, because that's what the schools teach about. Finding a shear greater than 20 knots at low level is rare indeed. Head up to the tropopause, and it's a totally different story.
At the junction between troposphere and stratosphere is this little phenomena known as the 'jet stream'. 100 knots of shear on the boundary of the jet streams is actually 'quite normal' and 'not bad'. I've seen 150 knots of shear over a very short distance vertically (less than 2000 feet) while penetrating the jets. This is still not a huge big deal, just gets a little bumpy, but, take a good look at SS1.
At the time of the roll event, the aircraft was accelerating on the initial rocket boost. It was in transonic, or early supersonic flight regimes. Penetrating a shear layer that gives a 100 knot difference in relative airspeed would set up some very very interesting asymetric shock wave scenarios, where the shock buildup on one side of the airframe is completely different than on the other. Even if this situation is just momentary, the asymetric forces will be huge, and cause a very noticeable deviation from nominal flight path projections.
Your frame of reference for shear is 'low and slow' in 'low performance' aircraft. SS1 is a very high performance aircraft, operating 'high and fast'. The primary contributor to aerodymanic forces will be shock waves and various forms of drag they produce. It's a whole different world, and everything you learned about 'low and slow' just doesn't apply to the 'high and fast' flight regimes. The SS1 flight mode at the time of the upset was 'at or near vertical' at transonic or supersonic speeds. It would not be at all surprising to see a major upset in the craft stability if it accidently penetrated the core of a 150 knot jet during that flight condition.
At this time of year, at those lattitudes, the core of the jets would be at an altitude in the area of 45 to 55 thousand feet. It would be unusual to see a jet core that far south in June, but, not unheard of. It's to late, and i'm really not inclined to go dig up old met charts from a couple weeks back, and see what kind of jet stream cores were over that part of california that morning. Sounds to me like that's what they may have hit, and, means the meteorology guys will be watching the jet charts a LOT closer for the next launches. Wouldn't surprise me at all that they even overlooked the detail, with an attitude of 'jet stream cores, over california, in june, who are you trying to kid?'. It's common in the winter, but not in the summer.
Its an aircraft with a rocket motor attached. Real spaceships can't use wings to slow themselves down and manuouveaure because there is no air to do it in! I'm sorry if I sound churlish but this whole enterprise to me smacks more of someones ego than anything practical. When they've solved the problems of manourveuring in a vacuum , long duration human life support (an O2 cylinder doesn't really count) , proper re-entry from near orbital speeds (which are required for any useful flights other than just oooh-isn't-it-pretty quick hops) involving heat shields and all the other necessaties than the US & Russia spent BILLIONS on developing THEN I'll be impressed. But a small plane with a rocket shoved up its backside? Umm no , sorry , its not a spacecraft.
Actually, there is a very interesting way to cool the spaceship during its descent from orbit: use the rocket fuel itself.
Why not? Cryrogenic fuels are extremely cold, and it is theoretically possible to route these cryrogenic fuels to actually cool down the spacecraft's structure during atmospheric re-entry if there is a safe way to vent the heated fuel. When Douglas Aircraft did its studies for the ROMBUS launch system in the early 1960's they actually figured out a way to use liquid hydrogen to provide heat protection during the descent. I'm sure that Burt Rutan knows about this idea and might use something like liquid methane as a rocket fuel for the ascent and as a coolant to protect the structure on Scaled Composites' Tier Two/SpaceShipTwo project.
This is very a very smart comment!
I agree... it would indeed be sad to see Spaceship-One go into a hanger and never come out again, except for a trip to the smithsonian 30 years later.
Of course, I really want to see a successful X-prize flight, followed by a series of private companies getting in line to order their own spacecraft from Scaled Composites.
NASA would make a very smart move by buying a couple of these and using them for actual routine space-flights. Of course, my intuition tells me that NASA would buy a few of these and then somehow figure a way to make a launch cost 100 million with a 2-year turn around on launch times.
Can you imagine the not-so-distant future where there will be several companies around the globe operating these craft, performing such tasks as launching microsats, ferrying world leaders around the globe in a matter of a few minutes, etc.? It's going to be amazing. If it progresses to the point where several companies are operating spacecraft, then NASA will have no purpose, other than perhaps acting as a regulatory agency like the FAA.
Skiers and Riders -- http://www.snowjournal.com
A few months ago, I took a class on Pilot-Induced Oscillations (PIOs). As an aerospace engineer who works on military high performance aircraft, I know how bad PIOs can be, and just how deadly a problem they can be. This looks like a classic PIO, triggered by a control problem.
To summarize the two-day class into one paragraph, a PIO is an oscillation that is generally sustained by pilot inputs, is usually triggered by some external event, and has at least two common causes: rate-limited control actuators, or so-called "phase lags" (lag between input and output).
Relevant to this case, then, is the roll actuator (the hydraulic device responsible for moving the roll control surfaces). It sounds from the non-technical answer in the article "the actuator delayed moving one of the ship's flaps" like a rate-limited actuator. The pilot demanded a larger input faster than the system was able to provide, so the control surface hit its stop.
What ends up happening, in such a case, is that the pilot doesn't get the overall response he expects, so he puts in MORE input. But then it turns out to be too much, so he puts in a response the other way - but it takes a while to start reacting, so he puts in MORE input... etc. etc. etc..
Also, the "external event" in this case was probably a wind shear. You can have a PIO-prone system and it will fly just fine - right up until you hit that trigger event which is just large enough to throw you into a PIO - and then you're basically hosed. Nothing you can physically do will stop the PIO - OTHER than just releasing the controls and letting everything stop naturally - because it's the inputs that drive the oscillation. And you can bet that's quite frightening for a control-freak pilot who's afraid he's about to lose control. Takes a LOT of training in how to recognize it for what it is; stopping it is easy (if you have time or altitude) - just let go.
To fix a control system that has PIO problems, you can (a) increase the authority of the control device, (b) increase the response speed of the device, or (c) decrease the phase lag so it responds more quickly. None of those fixes are trivial, unless they're caused by a broken component.
I'm quite sure Rutan, of all people, is intimately familiar with this issue, and I have no doubt that he and his team will address it appropriately.
--Brandon / Split Infinity Music
The kind of turbulence of which you speak can have very drastic affects on an airframe. Particularly if the turbulence is generated by something heavy flying slowly and you are in something light. They will teach you in class to stay above and well behind anything heavy and slow in front of you. Note that slow for them may be in excess of your maximum attainable speed in level flight!
In other words, its certainly a real issue, but any turbulence encountered by SS1 was not due to turbulence from other craft.
To win the X-Prize, you have to do two flights within a 14 day period.
It's an important detail, because it means the vehicles have to be reusable with minimal refitting.
The Space Shuttle could never win the X-Prize, even if it were flying and qualified for the contest, because its turnaround time is too long.
Jon Acheson
All opinions expressed herein are my own, and not those of my employers, who are appalled.
The X Prize Web Site says its "fully funded until Jan 1, 2005", or 175 days from now. I presume some of the prize money or insurance behind it has time limits. That may be a reason why we are seeing a fair amount of activity in late 2004.
1) NASA did not do the whole "metric to english" conversion error; it was a private contractor.
2) The sub-zero temperature O-ring failure issue was indeed NASA's fault (Statistics rule #1: Never omit data (in this case, omitting successes and simply plotting failures) to simplify a graph.). However you can pick on anything from an organization that has launched tens of thousands of rockets of hundreds of designs.
Rutan didn't do one of the most basic things in spacecraft launch (don't launch in high wind conditions), well known since the V-2, because he was even less safety conscious than NASA. Rather than disappoint all of the people that came to watch, he launched anyway into a highly dangerous environment, and nearly killed someone in the process. If NASA behaved like this, every other launch would be catastrophic.
Rutan has far, far simpler requirements than NASA, and consequently can use a far simpler machine. Nearly blowing up his spacecraft in a case as simple as the X-prize, I'd never trust a dime to him for a real payload launch mission.
GIVE US THE CUTTLEFISH!