Posted on 02/21/2003 4:34:05 PM PST by yonif
For subsonic velocities, the drag force on the foam, which accelerates it back towards the shuttle, would be proportional to the cross sectional area of the foam times the square of the velocity.
However, for supersonic velocities, I think that the drag is much higher, due to the foam having to create the supersonic shock wave and high-pressure area at its bow.
Therefore, given that the foam has little mass, a large cross-section, and is in a supersonic flow, I think that it would be very rapidly accelerated backwards toward the shuttle wing.
Do you know the correct power of velocity for drag in a supersonic flow?
I was posting some things too. See #6
I probably learned that once upon a time, but I don't recall exactly. It probably has to do with the relationship between Kinetic Energy (KE) and Potential Energy (PE). KE is as stated previously. PE of a raised object given by:
E = M*g*h
where M = mass, g = acceleration due to gravity, and h = height. If we raise an object of mass "M" to at height "h" (assuming velocity = 0 at the top), then when it falls to the starting point, its KE will be 0.5*M*V^2 (assuming no slowdown due to drag).Thus KE = PE or
M*g*h = 0.5*M*V^2
This has to do with the fact that when the object falls through height "h" the time of descent "t" is related to "h" by
h = 0.5*g*t^2
which yields
t = sqrt ( 2*h/g)
The terminal velocity is given by
V = g*t
When we play with all these terms, starting from KE = PE, the 0.5 term gets in there. Yes, I may have made this too complicated, and maybe even made a logic mistake, and no I am not trying to be obtuse. That is just the way I remember it from long ago . . .
We looked at this on another thread, and it would be easier for you to visit that thread, than for me to rehash it here. Here are some links:
Drag coefficient vs. Mach number (for spinning metal cubes)
The data are for spinning steel cubes, 1/4 to 3/8 inch per side. I am not an aerodynamics whiz. These data may or may not apply to larger or smaller debris of arbitrary shape and roughness.
NASA knew they had a problem with the material coming off the external fuel tank. They should have grounded the shuttles like some people were calling for after STS-112 which was flight when material from the external fuel tank dented the SRB.
Supposedly, the crew could see the damage to the leading edge of the left wing. One of the crew emailed his wife about the damage. Rumor is that after the accident she brought this up to the suits at NASA and they sent a "group" out to see if indeed it was possible to see the damage by "eyeballing" using one of the mockup/trainers. The "group" supposedly concluded it was not possible to see the damage. The people that assisted the "group" with this, it is rumored, were agitated at this news since they did not agree and felt that it was obvious the crew could see the damage. From the flight deck and maybe from another spot.
NASA knew material was coming off the external tank and hitting parts of the system and they let the shuttle fly. Bummer....
<< NASA, "Well Boeing said it was OK." Boeing: "Well NASA has operational control. We just make the silly tiles for them." >>
The Siberia-based "Russian" branch of the abjectly-corrupt and systemically-dishonest NASA
[Never in the History of the Human Species has so much of the confiscated wealth of
America's (Of the world's, that is) most creative, innovative, productive and industrious Men been
S quandered on so few in their
Accomplishment of so little] can send a Soyez and; after they have dropped NASA's floating junkyard into the Atlantic; drop them back to Siberia.
Columbia's demise was as inevitable as was Challenger's as is the entire Rube Goldberg/Heath Robinson-Joint-Venture designed and low-bidder gummint-contractor built "space" shuttle boondoggle.
NASA and its contractors current one-legged-man-in-an-arse-kicking-contest-like exercise in butt covering and buck shuffling brings to mind the valiant efforts of the last American Man of Moral Integrity to have been allowed near NASA, the Modern American Hero, Morton Thiokol's Roger M. Boisjoly.
Engineer Boisjoly predicted Challenger's loss and paid the price extracted by our much-vaunted Peter-Principled feral-gummint bureaucracy and by its universally-corrupted-by-the-relationship suppliers and contractors from all those who dare challenge the bureaucrats' systemic "the world is flat" and "the emperor is not naked" approach to building their own unearned power and influence by the inevitably-corrupt squandering of other peoples confiscated wealth.
Well, now we're experiencing the aftermath.
Memo writer says Thiokol froze him out of work:
Reassignment given 2 workers in O-ring warning
Houston Chronicle, Jan. 25, 1987A MORTON THIOKOL Inc. engineer who warned of problems with the Challenger's solid rocket booster O-rings six months before the disaster last January says the company has turned him into a "non-entity" because of his revealing testimony before the Rogers commission.
The commission blamed the shuttle accident on the faulty O-ring seals in the rear of the Challenger's right solid rocket booster, manufactured by Morton Thiokol.
The engineer, Roger M. Boisjoly of Willard, Utah, is one of two men who wrote in-house memos before the disaster warning of a potential catastrophe because of problems with the booster's O-ring seals. On the eve of the January Challenger launch, Boisjoly recommended that Challenger not be launched.
The other man is Richard C. Cook, 40, a former senior analyst with the National Aeronautics and Space Administration headquarters in Washington, now with the U.S. Treasury Department. Cook also testified before the Rogers commission. [...]
Boisjoly is still on the Morton Thiokol payroll but he is not working, he said in a recent telephone conversation.
After testifying before the Rogers commission, Boisjoly was assigned to a team of Morton Thiokol engineers charged with redesigning the solid rocket booster (SRB). But, he said, he was never allowed to participate and wasn't allowed to attend meetings, and has now stopped reporting to work. "It was a terrible environment," he said.
"On the one hand, I was part of the redesign team but on the other hand I wasn't allowed to participate in the meetings. So basically, I was a non-entity, if you will," Boisjoly said. [...]
Allan McDonald, ther Morton Thiokol engineer who had warned about the O-ring problem and who also testified before the commission, was reassigned by the company after his testimony. [...]
Without mentioning Boisjoly, company President Charles S. Locke later told the Wall Street Journal that "people are paid to do productive work for our company and not to wander around the country gossiping with people."[...]
"I didn't know any of the Morton Thiokol guys, but the shuttle flight in April (1985) had suffered a secondary erosion of the nozzle O-ring," Cook said. "That had alarmed Roger and it alarmed people at the Marshall Space Flight Center. The NASA center was responsible for the rocket booster development."
Cook says he left the space agency because his job required extensive overtime, and he wanted to spend more time with his family. He left NASA before he testified, but not before his warning in-house memo had been publicized.
"I felt freer to speak to the Rogers commission than if I had stayed at NASA," said.
"The people at NASA were angry because I spoke to the press (about the O-ring problem). I was told to say things to the press and the commission that I did not think were right, and I was told someone on the commission wanted to discredit me.
"Actually, my memo only repeated what some of the most senior NASA officials were saying (about the O-rings) and the most alarming stuff I didn't even put in my memo. There were (NASA) headquarters' engineers with 20 and 30 years experience who knew about the seriousness of the problems, and they were never called to testify by the Rogers commission."[...]
It's a very old social dynamic.
| We can't imagine why getting information is being treated like the plague. Apparently the thermal folks have used words like they think things are survivable, but marginal," Daugherty said. |
| That's what is bothering about this whole thing is the coverup. Even engineers on the inside can not seem to avoid flying safes. |
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