Daily Archives: Nov 4, 2014

View 849 Tuesday, November 04, 2014

“I have observed over the years that the unintended consequences of social action are always more important, and usually less agreeable, than the intended consequences.”

Irving Kristol

“Transparency and the rule of law will be the touchstones of this presidency.”

President Barack Obama, January 31, 2009

1030 Wednesday: Hiking with Niven and Barnes.  Back after lunch.   Obama lost.  Republicans would do well to understand that they didn’t exactly win: Obama lost. Now Republicans have an opportunity to show what they are for, and that they are competent, and that they can govern. That will take work, because it is not obvious to anyone including me.  Better than what we have, yes. Well and competent needs to be demonstrated.   Having said all that, Hurrah!

1630 Tuesday Studio City: The polls are still open, and Fox News says that it’s a very close election. It is a very important election. Part of its importance is that there has been a resurrection of conservative Democrats, and that may halt the Democratic party’s race to the extremist liberal/progressive position; but that’s speculation like everything else. An actual repudiation of Obama at the polls would be important. There has already been a political repudiation, with Democrats up for election inviting Obama to support them with money but to stay out of their districts.

I expect that many of the elections will be decided by recounts and decisions about fraud, but that’s speculation too. I’ll have more comments when there is something to comment on.

Here’s an account of the SS2 disaster:

Crash Analysis: How SpaceShipTwo’s Feathered Tails Work

Virgin Galactic’s SpaceShipTwo in its "feathered" configuration, with tails upright. Credit: Virgin Galactic

The cause of the deadly crash of Virgin Galactic’s SpaceShipTwo on Friday remains unknown, but the commercial spaceplane’s feathered reentry system looks to have been involved. Investigators at the National Transportation Safety Board (NTSB) determined that the vehicle’s copilot moved a lever to “unlock” the feather system earlier than planned, and two seconds after the feathers deployed, the spacecraft disintegrated.

The details of how or why this happened are still unclear. The feather system is normally used after SpaceShipTwo has already climbed to the peak of its parabolic flight path and begun to descend, to help the vehicle slow down and stabilize as it flies back to Earth. In fact, the design was one of the major innovations that enabled SpaceShipTwo’s predecessor, the smaller SpaceShipOne, to perform the first manned commercial spaceflight in 2004 and win the $10 million Ansari X-Prize.

SpaceShipTwo has two tails, one pointing straight back off each wing. Each one acts as a rudder, and has a small, horizontal flap at the back, extending to the outside. When the plane is descending, both tails can pivot upright, together, from zero to 90 degrees, so that they stand “vertically” behind the plane. In this configuration, the tails and flaps create drag. This “feathering” effect is similar to that of a shuttlecock in the game badminton. The shapes of both are designed to incite high amounts of drag from air resistance, and both are extremely aerodynamically stable, meaning the drag forces will always end up pushing the plane, or the shuttlecock, into the same orientation (a shuttlecock will always turn to fly cork first, and SpaceShipTwo’s feathered tails ensure it will reenter Earth’s atmosphere at the correct angle).

During a normal flight, SpaceShipTwo is carried upwards by its mothership, WhiteKnightTwo, and released in midair to ignite its rocket engine for the rest of the climb to the edge of space. During all this time, the twin tails point straight out behind its body in the “de-feathered” configuration. When it’s time to make the trip back to the ground, SpaceShipTwo’s pilots can deploy the feather, pivoting the tails upright. When pointed upward, the tails are at right angles to the direction of airflow, creating a huge amount of drag on the vehicle, which slows it down without overheating the spacecraft. This method works because SpaceShipTwo is not coming back from orbit; from the edge of space (it flies to a peak altitude of 110 kilometers) its top speed is low enough that the feather is enough to slow it down safely. Orbital spacecraft return at such high velocities that they require heat shields to protect them.

The feathered design has already proven itself in previous SpaceShipTwo test flights. During one test in September 2011, the spacecraft’s pilots briefly lost control of the vehicle while gliding down to Earth, but regained stability by moving the tails into the feathered configuration.

During Friday’s flight, the pilots normally would have deployed the feather when the space plane had reached a speed of Mach 1.4 (1.4 times the speed of sound) during descent, but the copilot Michael Alsbury unlocked the rudders early, when SpaceShipTwo was going Mach 1.0, according to NTSB Acting Chairman Christopher Hart. That action alone should not have been enough to pivot the tails upright, however, because neither pilot took the further step of turning the feather handle to actually move them, Hart said. Somehow, the tails rotated upward anyway, and the increase in drag at this point in the flight proved disastrous.

It is now clear that the Virgin Galactic SpaceShip Two was torn apart by aerodynamic forces after the ship entered the “feathered” “reentry” mode while still in powered flight beginning its vertical ascent to whatever maximum altitude the mission had planned. The hybrid engine worked as planned, and survived the destruction of the craft.

We can conclude with some confidence that what happened was that very early in the powered flight of SS2 when the ship was still at the breakaway altitude – 30,000 feet or so – the locking bar that keeps the “feathers” from swiveling was released. The ship was at something above Mach 1 at 30,000 feet.

This is at about ¼ atmospheric density at sea level so call it 250 millibars pressure, and the ship is moving above Mach 1. It is not clear why the feathers, which were now free from constraint, would rotate, but SS1 was designed to be a shuttlecock when the feathers are deployed, and to remain aerodynamically stable while moving through the atmosphere in that condition. The control surfaces on the feathers are presumably designed that way, and apparently, so soon as the feathers were free to rotate, they did so.

This would rotate SS2 to try to fly with its belly to the direction of air resistance, making for the stable shuttlecock attitude as the ship falls into the atmosphere at what I have been told is a velocity of Mach 1.4 or so; but note that in that situation the engine would be off, having burned all its fuel to get SS2 to altitude above 100,000 feet. Unfortunately, the engine, was still working, and would be trying to push the ship forward nose first, not at a high angle of attack. The resulting stress would be resolved by tearing the ship apart while the engine continued to thrust. What angle of attack it would now resume (so long as the engine continued to operate) isn’t easy for me to visualize, and I don’t know how long the engine ran, but by then SS2 was no longer under control. One observer has told me that “pieces fell off and then it came down like a lawn dart.”

I am appalled to hear that NTSB estimates it will take them more than a year to complete their report, and meanwhile any replacement of SS2 will not be allowed to fly. It’s pretty clear that this was an accident easily prevented, either by better control design – I’d be glad to do the human factors engineering if asked, but there are surely plenty of engineering psychologists with more recent experience than mine – coupled with better operations instructions. We can speculate on why the copilot – who perished in the crash – unlatched the bar that keeps the feathers secure, but we can be pretty sure no one will ever make that mistake again.

NTSB should issue the report by the end of the year so that Sir Richard Branson can get to work replacing SS2 and getting Virgin Galactic back on schedule. SS2 was never going to be a pathway to suborbital flight. It won’t get us to Tokyo in two hours, nor will any of its descendants. But it will give us operational experience in near earth space. A ship harbor is supported by harbor sightseeing cruises as well as by ocean liners.

2300. Alaskan polls close with Republicans ahead in the Senate race there.  The Republicans will have at least 52 Senators, and have gained 12 seats n the House. The country has repudiated Hope and Change and The One You’ve Been Waiting For.  Now it is up to the Republicans to show they can actually accomplish something.

Before that, there may be a Constitutional crisis, as Obama attempts to use his Executive powers.  He may try an amnesty move, and he will almost certainly try for a series of judicial and executive appointments while he can count on a Senate majority.  This will not sit well with many.  November, December, and early January may be very interesting times, and after that there will still be the Executive Powers.

“Do we falsify the resume? Yes, we do. We call it ‘spicing of the resume’.”

<http://www.theguardian.com/us-news/2014/oct/28/-sp-jobs-brokers-entrap-indian-tech-workers>

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Roland Dobbins

It’s late and the election is over.  Time now to devise an actual program. It is not clear that the establishment Republicans know how to do that, but we can hope.

Freedom is not free. Free men are not equal. Equal men are not free.