Remember the troublesome ceramic tiles on the Space Shuttle? My rocket scientist neighbor has one of those tiles, and just sent me this:
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New post on The Rocketry Blog
What coats a Dragon
by rocketry
What a difference a day makes...
(pic here)
What difference a day makes - on right Dragon in Space a day before splashdown picture
So what keeps it from burning up on entry?
The Heat Shield
PICA-X (MBRT )
Phenolic Impregnated Carbon Ablator (PICA) was developed by NASA Ames Research Center. An improved and easier to manufactured version called PICA-X was developed by SpaceX in 2006-2010 at cost 10 times less than the NASA PICA. A PICA-X heat shield is theoretically re-usable hundreds of times with only minor degradation.
The Paint
SOLEC's LO/MIT-I Radiant Barrier Coating
Read about it here
http://rocketry.wordpress.com/2012/05/31/what-coats-a-dragon/
This is usually used as a reflective barrier roof coating.
rocketry | May 31, 2012 at 5:09 pm | Categories: Space news | URL: http://wp.me/pGeu-T2
I sent Hugh Jass an email congratulating him on the latest application of Modified Bitumen Roofing Tar.
I know who he is, and his secret is safe with me.
But is it available in black ???
Yes, after re-entry from space:
PICA-X heat shield may be reusable hundreds of times but for this program NASA requires them to use a new vehicle for each trip.
When I first saw the capsule last week, I thought it looked like the mixer off a cement truck. And they paid $200M for that?
That concrete mixer is designed to haul astronauts to the Space Station, instead of buying lift from Russia.
Space X had 3 kinda' simple launch failures before their first success. On this launch, one of the nine engines didn't come up to power with the others, and it was shut down at something like T minus 0.5 seconds. That delayed the launch only 3 days.
I don't know any of the prices, but they are keeping NASA at arm's length. At Canaveral they are behind a locked gate. Reportedly, they run it like a real private enterprise, and not a NASA or Pentagon pork barrel project.
It's too bad Elon Musk is chasing the elusive electric car dream with his Tesla. I don't know the numbers for his cars, but it takes 550 lb of batteries to power a Nissan Leaf for 100 miles, which you can do on less than 20 lb of gasoline. Think of all the extra structure, brakes, tires and suspension to carry that extra 500 lb. in a small car. That's not to mention charge time at 30 or more amps, 240 volts.
rdr
Be careful Ralph. The parrots may blab on you - giving away yer secret !
Garnet
Historically the ablative heat shield has been considered to be altered by the ablation process. Conventional thinking said that the heat shield deformed by the ablation would disturb the aerodynamics on reentry. This could cause potentially catastrophic results due to the loss of desired S/C orientation to the velocity vector. The deformed heat shield could cause the S/C to skip on the atmosphere like a stone on the water, could expose unprotected surfaces to reentry heating or alter the reentry trajectory sufficiently to make the reentry environment unsurvivable. A visit to some of our space flight museums will show you just how much the ablating heat shields were deformed in use. Perhaps the energy dissipated during reentry could alter the properties of the ablator sufficiently to make it unusable for a second mission.
When we compare the weight of electric car batteries to the weight of gasoline required to travel 100 miles we make an unreasonable comparison. We should compare the weight of the electricity to the weight of the gasoline and oxygen consumed during the travel but that is also unreasonable. Perhaps the weight of the entire propulsion system should be compared. I think a conventional vehicle would still be lighter but I'm unsure of how much.
An article in the Seattle Times noted the charging stations in WA on I5 would soon be operational. These are to be located every 50 - 60 miles apart in sites of public interest. The article went on to say an 80% recharge would be accomplished in about 30 minutes. No mention of cost was made nor how many cars could be charged simultaneously. It might be a slow trip.
Everyone talks about the pollution factor of gasoline and diesel fuel but,
I wonder how much of our natural resources it takes to recharge a "green" car battery?
They have to be generating the electric power from a coal fired plant, atomic power plant, water source, or wind power. So how many steel mills (who manufacture the steel for wind mills, water turbines, coal mining equipment), plastic plants who make the battery cases, mines who mine the ore for the battery core, electrical parts and wire manufacturing, etc,etc, are green?
We do more polluting trying to manufacture green products then what the products reduce.
You may as well fart in the wind. All this green crap does is cost us more money and taxes!
Dennis, we give $2 Billion a year to big oil, year after year, and that is kind of mature technology. They don't pay any US income taxes, either, in spite of being the most profitable corporations in history. Let them pay their fair share.
Alternative fuels are a good venture. Plugging electric cars is not, due to the basics of the extra weight, unless somehow that encourages battery advancement. You do get some energy recovery with regenerative braking.
It's funny to see how state of the art car batteries were developed for the celfone and laptop market..
You should be able to judge the weight of an electric car by comparing its tire size to the tires on its gas equivalent. If you knew the gas equal of a Leaf, you should be able to go to TireRack.com or somewhere and see the sizes and capacities. The Tesla Roadster is 4-500 lb heavier than the Lotus it's based on, IIRC.
As for electricity source, I believe power plants are converting from coal to gas at a rapid rate, due to it now being so plentiful and cheap, although last I read, we still get a little over half our electricity from coal.
There's no free lunch, except for big corporations.
rdr