LABRIE@gecrdvm1.crd.ge.com (11/16/90)
It may be a little late, but heres the info anyhow.
Columbia originally used only carbon-carbon tiles for thermal protection
on re-entry (Except on the OMS pods). I'm not sure if Enterprise had tiles
put on for testing or not. But there is a sort of famous picture on either
Columbia or Enterprise gliding in with about a third of its tiles missing.
I remember the quote at the time being, "Looks like the cat dragged it in."
The problem was the glue used didn't penetrate into the tiles enough. So all
the tiles were removed and glued back on. A lot of people joked saying they
should have used Elmers Glue. But Elmers is water soluble- big problem.
Challenger was insulated using Nomex (?) felt insulation blankets, each
being about a square yard. It also used tiles but only in high temperature
locations like the nose, wing tips, hinges on the bay doors, and the belly
of the shuttle. You can expect about 500 to 1000 of these tiles to be dammaged
per flight. Most can be repaired in place by drilling out the pits or holes,
filling with paste, and sanding smooth. But about 100 to 150 of these will
be beyond repair and need to be replaced. Technicians have to carefully
remove the bad tile without dammaging the surrounding tiles or the shuttle
fuselage, make a cavity casting, and ship the casting to (I think) Rockwell
so a replacement can be made. There is no margin for error on the size.
Repairs to the felt blankets is similar to fiber glass work on a car or
boat. In comparison with tile repair, one square piece of blanket will take
the same amount of time to glue on as one tile. So you can see the advantages
of the blankets. An easy way to tell most of the tiles from the blanket
squares is, the tiles are usually black or grey and the blankets are white.
=====================================
John E. Labrie
GE Corporate Research and Development
Schenectady, New York USA
Views above can only be mine, no one else wants em.
I may be crazy, But I have a gooood time!dil@mace.cc.purdue.edu (Perry G Ramsey) (11/18/90)
In article <90319.213006LABRIE@GECRDVM1.BITNET>, LABRIE@gecrdvm1.crd.ge.com writes: > Columbia originally used only carbon-carbon tiles for thermal protection > on re-entry (Except on the OMS pods). All the vehicles use carbon-carbon , but only on the nose and the leading edge of the wings. It's the gray stuff. The black and white tiles are silica fibers which have been sintered to form a little brick. The black ones have a different coating, so they will emit more radiation at high temperatures. The top of the doors and some and a few other places are covered with a nomex felt which is covered with a white coating. This is known as FRSI (Flexible Reusable Surface Insulation.) > The problem was the glue used didn't penetrate into the tiles enough. So all > the tiles were removed and glued back on. A lot of people joked saying they > should have used Elmers Glue. But Elmers is water soluble- big problem. The glue held fine. The tile was too thick to stand the load and split. Densification increased the density of the tile and it's strength near the glue line. > > Challenger was insulated using Nomex (?) felt insulation blankets, each > being about a square yard. It also used tiles but only in high temperature > locations like the nose, wing tips, hinges on the bay doors, and the belly > of the shuttle. Challenger's TPS was not radically different from Columbia's, with the exception of the wing glove area. It's black on Columbia, white on Challenger. Discovery and Atlantis use AFRSI (Advanced FRSI. What are they going to call the stuff that's more advanced than AFRSI? But I digress.) in moderate temperature areas like the sides of the vertical stabilizer and the top of the wing. This is a small blanket about 1 ft square, and is about 1 in. thick. It is full of glassy fibers. > fuselage, make a cavity casting, and ship the casting to (I think) Rockwell > so a replacement can be made. There is no margin for error on the size. Lockheed. There is a significant gap between each tile to accomodate thermal expansion, and a variety of devices to fill gaps. > > Repairs to the felt blankets is similar to fiber glass work on a car or > boat. In comparison with tile repair, one square piece of blanket will take > the same amount of time to glue on as one tile. So you can see the advantages > of the blankets. An easy way to tell most of the tiles from the blanket > squares is, the tiles are usually black or grey and the blankets are white. Discovery and Atlantis have a lot of white tiles. Challenger and Columbia had/have a lot more. > John E. Labrie -- Perry G. Ramsey Department of Earth and Atmospheric Sciences perryr@vm.cc.purdue.edu Purdue University, W. Lafayette, IN USA dil@mace.cc.purdue.edu Why waste time learning when ignorance is instantaneous? -- Hobbes
gregc@cimage.com (Greg Cronau) (11/21/90)
In article <90319.213006LABRIE@GECRDVM1.BITNET> LABRIE@gecrdvm1.crd.ge.com writes: > > It may be a little late, but heres the info anyhow. > > Columbia originally used only carbon-carbon tiles for thermal protection >on re-entry (Except on the OMS pods). Huh? Columbia, as well as all the shuttles, uses the black(and expensive!) carbon-carbon composite tiles for the nose and leading edges of the wings and vertical stabilizer. The under-bellys of *all* the shuttles use silica tiles with a black glaze. The OMS pods and other areas use the silica tiles with a white glaze. The blankets are for the upper surfaces of the wings, the cargo bay doors, and the rear side fusalage(sp?) areas. As I remember, the original material used for the tiles was a special silica and ????? compound that cost serveral thousand dollars per tile. Later, they found a boron-silicate substance that, while a little heavier than the original tiles, cost only several dollars per tile! >But there is a sort of famous picture on either >Columbia or Enterprise gliding in with about a third of its tiles missing. Huh? (again) No shuttle has ever glided in with a third of it's tiles missing. What you may be thinking of is when Columbia was first flown in to KSC on top of the 747 transporter. A large number of it's tiles were lost on the flight. >Technicians have to carefully >remove the bad tile without dammaging the surrounding tiles or the shuttle >fuselage, make a cavity casting, and ship the casting to (I think) Rockwell >so a replacement can be made. Huh? (once more) A shuttle tile is machined from a piece of the raw silica compound by computer controlled milling machines. It is then sprayed with a black glaze and then stenciled with it's ID number in yellow glaze and then fired. Every tiles exact size, orientation, and location is stored in a computer. If one needs to be replaced, they simply read the number off the tile, or look up it's number if it is too badly damaged. The tiles have about a 1/8 inch gap between them and their neighboring tiles. >An easy way to tell most of the tiles from the blanket >squares is, the tiles are usually black or grey and the blankets are white. A fair number of the tiles are white too. gregc@cimage.com