It seems that there are more ways to insulate the liquid hydrogen than foam on the outside. Have the overly educated college bred professionals at NASA even considered any other way? Why couldn't the inside be lined with some form of insulation prior to completing the tank assembly or make it clamped together for repeated inspection and relining? It could be a double hulled tank that would provide the insulation as well as be filled with an insulating medium in between hulls, and any arguments saying that it would become too heavy or less capacitory are moot as there are materials light enough and gas pressures could be increased with double lined tanks. Where has common sense gone? It would seem that colleges remove any semblance of such a needed talent. In any case, I have read that the Space Shuttle Program is so outdated given the state of the art technologies available as alternate means of obtaining atmospheric escape that it is fairly criminal to go on with the current space program. The Space Program has to be revamped and updated, period.

Let's see , gas pressure is moot since the hydrogen and oxygen are already in a liquid form.

Lining the inside of the tank would be bad since if the foam broke off inside the tank it would clog the pumps and engines , especially the engines , since the liquid fuel is first run through the "bell" of the rocket nozzle , which is built of thousands of small tubes welded together, this keeps the nozzle from melting , then the fuel is squirted out through an array of at least a thousand small jets at the top of the "combustion chamber".

this is the design that allows the shuttles main engines to be reused.

so , foam in the fuel would ruin the main engines.

a "double wall" tank would be actually be more than twice as heavy , since the only reason to build a cryogenic double wall tank would be to insulate it with a vacuum.

also most composites do NOT perform well at cryogenic temperatures (liquid oxygen and liquis hydrogen) and many may actually ignite in contact with liquid oxygen.(carbon and oxygen burn, so carbon composites are out).

so we are left with metal shells to hold our really cold liquid fuel.

The liquid oxygen , liquid hydrogen is the second most energetic fuel combination in existance , the only exhaust is water , so the combination is ideal.

FYI the most energetic is liquid hydrogen and liquid flourine , but most people would take offense at the hydrogen flouride exhaust ,especially if they got caught in it. After all HFis a deadly corrosive.

Okay, however, #1, Liquid hydrogen is also compressed, so the point is not moot, as trucks delivering this fuel regularly do so at a pressure of 100 psig.

Double walled tanks may weigh more, but there are lighter materials that can be used inside the steel external tank and the size itself of such tanks again can be reduced as opposed to the single walled type due to a higher pressure capacity, again, as used on a daily basis with trucks. The cryogenic vessel on these trucks is a double walled thermos bottle with an outer wall of carbon steel and an inner wall of construction materials consisting of #1. aluminum, #2. 9% nickel steel, and #3. stainless steel. The annular space inbetween the walls is not just a vacuum, but consists of Perlite insulation and Superinsulation. A typical liquid hydrogen storage tank contains the liquid hydrogen at 150 psig. It is concievable and I believe possible, therefore, to use a double walled tank on the Space shuttle at a reduced size or 2 smaller double walled tanks, to compensate for the weight differential, therefore eliminating the need for foam insulation on the external suface.

There is also another method that could be possible, and that is the use of two separate propulsion systems and to launch from runway level or by use of rails at a gradual angle of attack with one to a ceiling of between 90,000 and 100,000 feet, and then engage the other to achieve orbit. The first would be with the use of two externally mounted Pratt & Whitney J61 turbo-ramjet engines, each producing 42,5000 lbs. of thrust, to attain the 95,000 ft. altitude ceiling for these engines, and then engaging the Shuttle engines, sans the two booster rockets and huge fuel tank, (No longer neccessary.), replaced and fueled by my proposed smaller double walled liquid hydrogen tank/tanks, as described above and another relatively small fuel tank for fueling the ramjet engines. This technology exists today and can be employed, so my points are not irrelavent.

I have been to the Pratt & Whitney site, and Lo and Behold, is a picture of PWR's X-1 scramjet engine powering the first X-51A simulated flight at NASA's Langley Research Center. So apparently, we may soon see a change in how our Shuttle Astronauts attain orbit. So I would have to venture that any argument regarding the present space Shuttle Program and the space shuttle problems, including my own heretofore stated, will hopefully soon become moot and irrelavent, except those that might be a quick fix for the interum use of the Space Shuttle extant and the foam shedding problem. They really should just shut it down untill this new engine is fitted to the next generation Space Shuttle vehicle. The site address to picture of Scramjet engine is: <link>

Two words:

Gillette.

Foamy.

But seriously, at first, they used to paint the tank, and then they quit in order to save weight. They traded the weight of the freaking paint for more payload. If your alts weigh one more ounce, you can fuggeddabouddit.

The fuel is liquid, which means it is not compressible. For a given mass of hydrogen or oxygen you get essentially the same volume even if you pressurize it more. So, no tank size reduction.

However, a "from scratch" design could certainly come up with a better solution than fragile exterior foam.

I think they will keep flying the shuttles until they blow all of them up. Each failure is seen as just a reason to "get it back". Continuing to fly after Columbia is reckless.

Let alone the circular logic of needing the shuttle to get to the space station, and needing the space station to give the shuttle someplace to go.

If we really want to keep putting people up in space, which is really unnecessary, we should pool our resources with China and others and develop a better vehicle.

VI.E Compressed/Liquid Tanks

VI.E.1 Low Cost, High Efficiency, High Pressure Hydrogen Storage

Approach

Quantum will be using 10,000-psi compressed hydrogen storage tanks to achieve the DOE hydrogen storage technical targets. Techniques to be explored include:

•Composite design and process optimization to improve weight efficiency and reduce material usage,

•Embedding sensors to monitor cylinder health and reduce over-design requirements (resulting in lower weight and cost), and

•Cooling hydrogen to increase storage density.

The goal in Phase I of the project is to produce development tanks that reduce the amount of composite materials required without sacrificing safety through design and process optimization. Since the tank is a significant portion of the system weight, the optimization efforts will also improve system level efficiency.

•Successfully employed low-cost, commercial grade carbon fiber to fabricate 10,000 psi storage tanks with the same level of performance as tanks using aerospace grade carbon fiber.

•Identified strain signatures for healthy and damaged tanks under cyclic loading. This information will be used to monitor the state of the tank during service and help determine if the tank is no longer safe for use.

•Completed finite element analysis (FEA) model of composite tank for predicting thermal behavior during gas charge and discharge. Verified FEA model through test data.

You can't compress liquid hydrogen, eh?

During launch, the functional use of the foam is close to the end.

NASA and this article seem to have proven it is very hard not to let some of the foam fall. Instead of concentrating on preventing the foam from falling, why not trying to make sure the falling foam do not do any damage.

I am starting a wiki to facilitate this discussion. Click here to visit. <link>

Excellent point. Since they seem dead set against changing the design and upon killing more astronauts with this faulty design, NASA should at least put light-weight, disposable shields on all vulnerable shuttle surfaces to protect against foam (or small space junk) strikes.

One other thought --- why the heck can't they incorporate some sort of fine, strong net into the surface of the foam to prevent it from falling even if it cracks and loses adhesion?

BTW, I knew NASA engineers at Lockheed who worked on the tile design after the shuttle was upsized to hold spy satellites (the original design was smaller and used tried and true heat shields perfected in the lunar program). To a man, and at least one woman, they all swore that the tiles were a horibly dangerous desperation fix to an intractable engineering problem that cropped up when they NASA was forced by Congress to upsize the Shuttle.

In retrospect, we're missing the point. The problem is not the foam, or the external tank design, or whatever other red herring. The problem is the tiles, which I suspect are too fragile even to support light protective covers, which will become quite "heavy" during the aerodynamic pressures of liftoff.

The tiles, in turn, were necessitated by Congress, which mandated that, in order to pay for itself (what a joke!), the Shuttle should be upsized to launch spy satellites. NASA objected strongly, the Air Force screamed, and Congress ignored them.

After the Challenger blowup, the Air Force switched back to Titan rockets for its spy satellites. Now the main justification for the overly-huge Shuttle is the International Space Station, another dangerously obsolete boondoggle. Fortunately for us, the Russians have a crude but reliable alternative to the Shuttle for ferrying people and supplies. We should be thinking along the same lines.