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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."
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.
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
It's doubtful that they could get their big vehicle together and working by the end of the year. John has said if Rutan fails they might make a push (ie, work on it more than the current 2 days a week and evenings) to get done by the end of the year for an attempt.
According to John there is no other team even close, and I believe him.
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.
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?
Rutan probably had to change the dial from "10" to "11"
Supreme executive power derives from a mandate from the masses, not from some farcical aquatic ceremony.
Even when one ignores the potential billions of dollars in the suborbital tourism market, this also opens the door for intercontinental spaceflights. Even if they don't go into orbit, it still lets people get around the globe quite fast ("one hour from New York to Tokyo") without having to worry about things like sonic booms along their path. Such intercontinental spaceflights are a nice transition to orbital flights.
Even if that's not enough to impress you, it certainly fills me with amazement.
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.
I wouldn't really class Jon's team as close. Sure, they're definitely getting there, but the highest controlled flight they've done was only 131 feet high with a subscale model. Several of the other teams could have done the same thing and we'd never know about it - its just that Armadillo are very open about their progress.
Actually, that's one of the things I really admire about Armadillo Aerospace - they've kept very little to themselves - anybody with some money, patience and skill could get going quite quickly by learning from the Armadillo website.
Serious X-Prize contenders realized early on, there's a lot of rocket technology available 'for sale' out there. They bought rocket engines, and concentrated on the difficult part of the engineering problems, the vehicle to get into space and back.
There's 2 teams that have a chance of actually completeing the X-Prize flights this year. It's interesting, Scaled has used the 'all aerodymanic' approach, with a mothership for first stage lifting to get above troposphere. Da Vinci project is 'all ballistic' with a mothership to provide first stage lift above troposphere.
Scaled is currently the odds on favorite to achive the X-Prize flights first. They have a really good chance, they have all the flight hardware, and it's been thru rigorous testing. Still, manned space flight is HARD (just check with Nasa for reference), and it's NOT a given that the SS1 + WK combination can complete 2 more flights without incident. A serious incident with either vehicle, and Scaled will be out of the running for the X-Prize, there isn't time left to replace either of them.
Da Vinci project has flight tested engines, but, they have yet to flight test an all up final configuration. They have the permits in place, and, the hardware is built. They are expected to start flight testing within the next 6 weeks.
Armadillo, well, they are tinkering with rockets, and writing a blog about it. They dont have a vehicle to mount an all up configuation rocket in, and they dont have a design to build one from. The X-Prize must be claimed this year, and Armadillo hasn't even got a vehicle design yet. No, they are not in the running, and have no hope of being in the running. If you haven't done the engineering analysis on a design, to validate it should be capable of withstanding the launch/recovery portions of the flight, and got the hardware built, ready to fly this summer, you are not in the running for the X-Prize. No matter how much money you throw at it, you are not going to design/build that package in the next 4 months, and if it's not flight ready in 4 months, you cant meet the requirements for winning the X-Prize.
"If you just want to get up there to launch a satellite" which has been done to death if you ask me.... I mean how many countries and companies already do this regularly, OH WAIT!
The prize is for Manned Flight.
Speaking of which, isn't "Space Flight" an oxymoron? Flight implies flying, movement through a medium using lift mechanisms. I was under the impression that generating lift required a medium a little more dense than the vacuum of space. Anyways... I don't see your Sub-Orbital Rocket Plane or Missile on the X-Prize list of contenders.. so that makes you:
a hater, don't hate.
A fool throws a stone into a well and a thousand sages can not remove it.
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