Posted on 03/10/2021 10:11:57 AM PST by CondoleezzaProtege
On Jan. 27, 1986, Allan McDonald stood on the cusp of history.
McDonald directed the booster rocket project at NASA contractor Morton Thiokol. He was responsible for the two massive rockets, filled with explosive fuel, that lifted space shuttles skyward. He was at the Kennedy Space Center in Florida for the launch of the Challenger "to approve or disapprove a launch if something came up," he told me in 2016, 30 years after Challenger exploded.
His job was to sign and submit an official form. Sign the form, he believed, and he'd risk the lives of the seven astronauts set to board the spacecraft the next morning. Refuse to sign, and he'd risk his job, his career and the good life he'd built for his wife and four children.
"And I made the smartest decision I ever made in my lifetime...I refused to sign it. I just thought we were taking risks we shouldn't be taking."
McDonald persistently cited three reasons for a delay: freezing overnight temperatures that could compromise the booster rocket joints; ice forming on the launchpad and spacecraft that could damage the orbiter heat tiles at launch; and a forecast of rough seas at the booster rocket recovery site.
Twelve days after Challenger exploded, McDonald stood up in a closed hearing of a presidential commission investigating the tragedy. He was "in the cheap seats in the back" when he raised his hand and spoke...
"There are two ways in which McDonald's actions were heroic," recalls Mark Maier, who directs a leadership program at Chapman University and produced a documentary about the Challenger launch decision.
"One was on the night before the launch, refusing to sign off on the launch authorization..." Maier says. "And then afterwards in the aftermath, exposing the cover-up that NASA was engaged in."
(Excerpt) Read more at npr.org ...
Well, not quite. Turns out stacked donuts of solid fuel had a more useful performance profile than other designs. The performance of a solid rocket fuel is a function of the combusting area. As solid fuel combusts, it erodes. If the erosion significantly increases or decreases the area combusting, thrust and chamber pressure change and if this reaches an inconvenient balance the booster might not produce enough thrust during a critical phase in the mission profile, or it might shut down or blow up. However as the 3 exposed faces of the cylindrical segment erode the surface area remains relatively constant and/or predictable so performance can be made optimal for the mission profile (in this case roughly constant thrust until burnout near the end of the gravity turn, with the SSME used to compensate).
The political benefit was just gravy...however we should take notice that a gravy train is needed for the successful funding of a federal project. Thus elevating such consideration to an engineering concern, provision of gravy, HHOS.
I worked at Corning Inc at the time, a division, Erwin Ceramics Plant. The material is actually a ceramic tile with a foam like interior. Very lightweight. About the size of a bar of soap. You can hold it in your hand at one end and get the other end red to almost white hot and not fall the heat.
We are referring to the foam insulation on the center fuel tank. i think you are talking about the heat shield tiles on the bottom of the orbiter.
That made me chuckle.
As someone who shouldn't have once told me...
"You like science fiction, right? Take what you think we might have, add 100 years, and you are getting close."
Should’ve had him investigating TWA Flight 800.
Center fuel tank, my ass.
I’m still waiting for flying cars.
If they had them, do you really think they would let us have them?
A people used to liberty blessed with high technology is very hard to control.
We almost didn't get the internet.
Did someone else sign off instead??
Big fan of alternate history fiction as well. Good question. Not really sure. It had direct and personal effects on me and classmates, but not so sure of the long term global changes. Perhaps, we’d have some form of space based SDI as that was the big project going on at the time.
IIRC, he was ‘overruled’ by higher ups....................
Wasn’t the booster fuel material more of a sludge as manufactured, that had to be poured into the casing? They couldn’t pour a 100 foot long tube without cracks or voids with would result in explosive failure, so they had to do smaller segments and stack them.
I don’t know, I read that sometime after the accident.
Original plans had the shuttle with an escape pod like the F-111 aircraft had. But it was determined as too costly.
Yes, that's very common for solid propellant. It was perchlorate, aluminum, HMX (a kind of plastic explosive, heheh), and some kind of binder like butyl rubber cured solid...they could pour it and it would solidify in the case. Way easier. Of course when Feynman visited the factory they were certifying the casings cylindricality by measuring 3 points on the top, a total fail. I think a lot of modern standards for GD&T (geometric dimensioning & tolerance) are a legacy of lessons learned from the investigation.
They couldn’t pour a 100 foot long tube without cracks or voids with would result in explosive failure, so they had to do smaller segments and stack them.
Another plus for using segmented propellant, manufacturability. But the segmented approach was really optimum for the required mission performance.
The shuttle program was just using a standard approach. I've done the same thing in candy rockets, cast segments in a mold and slipped them into a heavy paper tube with a plumbers' putty gasket between each segment to protect the exposed paper. The propellant segments deform a little when you compress the stack and the putty bonds with the paper. Some people use PCB pipe with similar effect. Makes the math easier, that's for sure.
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