Let me know if I should write a letter to NASA.

[g99]

This might sound stupid, but what the heck:

Why not change the shape of the underside to be more tirangular or curved. Like have the underside a "V" or "U" shape? That way the air currents will be deflected more to the side than hitting it directly on. Think swan dive compared to belly flop.


Or how about use the techniques that the jet fighters and supersonic aircraft use to reduce sonic booms and smooth out the air. If they can let the air slide by easier, would they need as much tileing?



_________________
"Hi!!" - Some person, somewere, at some time.
"It takes Thousands to fight a battle for a mile, Millions to hold an election for a nation, but it only takes One to change the world." - Dan Sandler 2002

<font size=-1>[ This Message was edited by: g99 on 2003-02-10 17:42 ]</font>

[Doodler]

On 2003-02-10 17:42, g99 wrote:
This might sound stupid, but what the heck:

Why not change the shape of the underside to be more tirangular or curved. Like have the underside a "V" or "U" shape? That way the air currents will be deflected more to the side than hitting it directly on. Think swan dive compared to belly flop.


Or how about use the techniques that the jet fighters and supersonic aircraft use to reduce sonic booms and smooth out the air. If they can let the air slide by easier, would they need as much tileing?



_________________
"Hi!!" - Some person, somewere, at some time.
"It takes Thousands to fight a battle for a mile, Millions to hold an election for a nation, but it only takes One to change the world." - Dan Sandler 2002

<font size=-1>[ This Message was edited by: g99 on 2003-02-10 17:42 ]</font>

Isn't the idea of streamlining to reduce drag? The idea of the shuttle is to slow down as quickly as safely possible once it enters the atmosphere.

[g99]

Doh!!! Question retracted. Slamming head into wall now. [img]/phpBB/images/smiles/icon_smile.gif[/img]

[Russ]

Hey Y'all:

The problem is not the glue letting go, it is the tile! Very early on, they had problems with the glue. That was solved before the first shuttle flight.

The problem is with the low structural integrity of the tiles themselves. Someone above mentioned that you can scratch one of these with your finger nail and that they were about as strong as a styrofoam cup. These are good descriptions. Because they have to be VERY POOR heat conductors they have to be mostly empty space. Because of this they are VERY FRAGILE.

All of the problems with the tiles falling out has nothing to do with the retaining system. The part of the tile in contact with the glue was still there. They have cracked and fallen appart. They have been hit by something and fallen appart. They've been blown out by the slipstream of the shuttle. They have all been due to structural failure of the tile itself. I can vouch for the fact that the glue they use will stick to ice (humoursly "anything") and will require a Dremmel Tool (tm)grind it off of whatever you stick it to.

Before you say "just build a stronger tile" remember that these have to be excellent thermal insulators. The rules of the universe so far are, The stronger the medium, the better thermal conductor it is (worse insulator). That's one of the reasons that copper (cu) is a better heat conductor than say neon.

I've been to several NASA engineering meetings (wind tunnels) and if there was a better way to do it, NASA would have it that way. [img]/phpBB/images/smiles/icon_biggrin.gif[/img]

[David Hall]

I mentioned before in another thread, based on another poster's idea (I think it was g99), that perhaps a simple sheet or mesh of light material could be glued over the outside surface in critical areas. I'm imagining a kind of "cling-wrap" that would help to strengthen the integrity of the surface during launch and early re-entry, but would burn off sometime before the highest heats are reached. This way the tiles wouldn't have to rely entirely on a single glued surface, but would also be attached to it's neighbors by the film. And it wouldn't add much weight to the whole.

It wouldn't be a panacea, but if used judiciously it might help protect the most critical areas from serious launch damage (if indeed that is what the problem is of course).

[dan-o2]

They should just install loonix. Duh.

[g99]

On 2003-02-10 19:51, David Hall wrote:
I mentioned before in another thread, based on another poster's idea (I think it was g99), that perhaps a simple sheet or mesh of light material could be glued over the outside surface in critical areas. I'm imagining a kind of "cling-wrap" that would help to strengthen the integrity of the surface during launch and early re-entry, but would burn off sometime before the highest heats are reached. This way the tiles wouldn't have to rely entirely on a single glued surface, but would also be attached to it's neighbors by the film. And it wouldn't add much weight to the whole.

It wouldn't be a panacea, but if used judiciously it might help protect the most critical areas from serious launch damage (if indeed that is what the problem is of course).

Nope david. It wasn't me, it was Mainframes
from:
http://www.badastronomy.com/phpBB/vi...c=3764&forum=2 (third post down).

Just giving credit. [img]/phpBB/images/smiles/icon_smile.gif[/img]

[kucharek]

The 19th century was the century of riveting, the 20th century was the century of welding and
the 21st century will be the century of glueing.

Many people underestimate the art of glueing, and if you don't trust glue, you shouldn't enter a modern airliner.

Harald

[Valiant Dancer]

On 2003-02-10 10:43, Bill Thompson wrote:
Let me know if I should write a letter to NASA.

Why, I wonder, don't they ask a computer programmer -- one whose job and experience is solving problems -- for a solution when confronted with a problem?

As I see it, there are things that need to change in order to insure that people can travel into space

#1. Forget about glue. The tiles should not be glued on but clamped on. The tiles should be anchored to the shell of the shuttle not glued on. I don't know if they even considered this. I am talking about redesigning the back of the tiles so that they have a lip and and indention going all around it and design the bare shell of the shuttle body so that it is equipped with titanium clamps to hold the tiles in place. Now, these babies are not coming off if they are hit by a micro-meteorite, a micro-asteroid, a bullet, a piece of metal traveling thousand miles of hours. Etc.

#2. They need to borrow from nature. Just as cars have crumple zones, the human body's bones are designed with varying thickness so that, if push comes to shove, a bone will break in the least lethal areas. This is why the bones around the knees and elbows are thicker. But in the case of the space shuttle, It is the physiology of a shark that is the area of nature that they need to borrow from. Whenever a shark gets a tooth broken off, a new one grows back to replace it. The skin of the shuttle can be in several layers. If a few tiles on the outer layer gets lost, there are tiles behind them that will pop out.

#3 It is just simple common sense -- and good hindsight -- to say that every mission should include a space walk to check the outside of the shuttle for damage and need for repair.

#4 The next shuttle mission -- maybe the next two shuttle missions -- should be focused on placing some sort of shuttle first aid kit and even an emergency escape pod into orbit.

#5 The navy designs modern war ships into compartments so that if one area of the ship becomes flooded, it can be sealed off from the rest of the ship. Also, F-14's are designed to save the life of the pilots if the aircraft is doomed. Borrowing from these two aspects of the Navy, it is easy to imagine a design of the passenger area at the nose of the space shuttle that is physically sealed off from the rest of the ship and is designed to break away in the event that the rest of the shuttle is lost.

Bill, As a fellow computer programmer let me say this. You don't understand the problem.

The problem was not the tiles became unglued. The problem was that some of the tiles became damaged. (Although after some new pieces were found, I'm beginning to wonder if a landing gear door didn't fail and cause a heating situation. But at least I'm not jumping to conclusions and writing letters to people infinately more qualified to know the particular systems and tolerances of the craft in question.)

Lifeboats add new orbital elements that one has to be concerned about hitting. Tile replacement kits were thought about and even test flown on the first couple of missions but the trade off between weight and probable ability to apply the tiles properly was deemed prohibited. You have to remember that when these birds were built, they were someones 50,000 piece jigsaw puzzle from hell. Almost every tile is different both in shape and thicknesses. That is an engineering nightmare. One could concievably carry around all the spares for all the thicknesses plus the fast drying adhesive. But then there'd be no room for cargo.

The crew compartment is completely seperate and designed to break off during a catastrophic event. It can't stand reentry, though.

Any solution to this problem will probably add weight. The point is to get the best solution for the least weight.

Since your expertise is in computer science and not aircraft mechanics, rocket propulsion, chemistry, or spacecraft engineering, why don't you just let the people who have those expertises discuss the wreckage, telemetry, and other available data to find the root cause and propose a solution.

[David Hall]

On 2003-02-10 21:53, g99 wrote:

Nope david. It wasn't me, it was Mainframes
from:
http://www.badastronomy.com/phpBB/vi...c=3764&forum=2 (third post down).

Just giving credit. [img]/phpBB/images/smiles/icon_smile.gif[/img]

Thanks, I was just too lazy yesterday to go digging up the thread myself. I placed unjustified trust in my memory. I shoulda known better. [img]/phpBB/images/smiles/icon_smile.gif[/img]

[g99]

David, David, David. Come on! After 1050 something posts of mine you should of known better than to think that something of value would come out of them. [img]/phpBB/images/smiles/icon_wink.gif[/img]
(i am hard on myself arn't I?)


No problem, i get lazy too sometimes.

[Bill Thmpson]

On 2003-02-10 15:39, DaveC wrote:
Besides, before we go off adding weight to the Shuttle fleet and seeking stronger glue, we may want to determine that tile displacement is indeed a problem. The tiles may have performed perfectly.

An article in this morning's Toronto Star (www.torontostar.com)covered some speculation that an ice ball may have formed at the wastewater vent and caused damage to the leading edge of the left wing when it broke free. Apparently this ice ball problem occurred at least once before (I think with Challenger in 1984) and the ice formed a basketball sized chunk. Heaters were installed after the incident to keep the vents from icing over but there may have been a failure. It's just one of many possible leads that needs to be investigated.

This interested me and I read the article in the TorontoStar. It seems like a convincing article because it seems to quote some NASA specialists.

Having said that, I have to say that it goes against what I have learned about Physics and I think a lot of scientists would agree with me. In High School Physics class, we put a glass of water into a class covered container and pumped the air out. At room temperature, the water boiled. Water, and Ice cannot exist in a vaccume.

But since this story seems to come from a reliable source and since it seems to back up its story with previous observations, I think we need to start a new thread of discussion abou this.

[daver]

Having said that, I have to say that it goes against what I have learned about Physics and I think a lot of scientists would agree with me. In High School Physics class, we put a glass of water into a class covered container and pumped the air out. At room temperature, the water boiled. Water, and Ice cannot exist in a vaccume.

But since this story seems to come from a reliable source and since it seems to back up its story with previous observations, I think we need to start a new thread of discussion abou this.

Not sure what you mean by ice not being able to exist in a vacuum. You know what a comet is made of, don't you? Maybe you mean that ice, under temperatures encounted in earth orbit, will eventualy sublime away. The key word here is eventually (also temperature--if the water vent was in shade the ice would be more stable).

[Irishman]

Bill, your description of computer programmers as problem fails to recognize that other jobs also act as problem solvers - notably engineers. NASA is full of engineers.

I think your comments have been adequately rebutted.

I would just add on to your comment about the need for pop-out replacement tiles, and other peoples comments on the tiles. Several of you seem to be under the impression that the tiles must be maintained pristine in flight, or the orbiter will be lost on reentry. The fact is, the designers recognized the fragility of the tile design chosen, and designed with that in mind. The shuttle can sustain a fair amount of damage to tiles and still function nominally. It can sustain loss of single tiles in multiple locations with no impact to safety. It has forgiveness built into the system, precisely because they knew it would see damage.

Another reservation about metal clamps or restraint bars - that would hinder the insulation abilities of the tiles, acting as a heat conduit and heat sink within the wings.

Doodler said:

And another thought, slightly unrelated, why not use a harder ablative shield on the leading edges and simply replace it at the end of the mission?

Actually, the leading edges do use a harder material. The black tiles (and the white tiles) are the silica based tiles. But along the front edge of the wings and the nose is the carbon-carbon structure. That is not the same fragile tile, but a harder, more rigid material that sustains the highest temperatures.

traztx, the wings on the orbiter need to be deployed on reentry, because they are part of the braking system. Note that in normal flight mode (aka like standard airplanes, as a glider) the glide path of the orbiter is that of a brick. It drops about 4 times as fast as any other aircraft. The training aircraft astronauts use to practice landing has to reverse engines to create enough drag to make it fall in the correct flight profile. But during the reentry phase, the shape of the orbiter's underbody is the braking mechanism to go from 12,500 mph down to about Mach 2. If it did not have the wings, it would not be braking as much.

Bill, no need for a separate thread. The icing issue is simple. It takes time for water to evaporate - even in vacuum. It depends on surface area. If enough water is vented at once, rather than fully boiling off, some of it will cool and ice, and then sublimate away at a slower rate. So you get the icicle.

[Bill Thmpson]

On 2003-02-12 13:30, Irishman wrote:

...Another reservation about metal clamps or restraint bars - that would hinder the insulation abilities of the tiles, acting as a heat conduit and heat sink within the wings....

Thanks for the information.

I have been rethinking all this and will have more to add to this tread this weekend.

I have a lot to add.

[Bill Thmpson]

By the way, I just heard on MSNBC that the latest theory is that what doomed the space shuttle was an impact from above into the top of the left wing.

[russ_watters]

Or how about use the techniques that the jet fighters and supersonic aircraft use to reduce sonic booms and smooth out the air. If they can let the air slide by easier, would they need as much tileing?

There are 3 flight regimes - subsonic, supersonic, and hypersonic. The rules are different in each - in hypersonic flight, the primary concern is HEAT. The space shuttle wing is not sharp like an F-16 because if you allow the ariflow to be attached to the wing root, you increase the skin friction drag and melt the wings off. The roundness pushes the shock wave out in front of the space shuttle, forming a barrier that reduces the airflow that is touching the shutle and therefore reduces the skin temperature.

[Taks]

mr. thompson,

in spite of all the issues and problems that NASA seems to run into, the general public seems to regularly forget (largely due to intense media scrutiny, fair or not) that NASA truly is composed of some of the best and brightest engineers and scientists the world has to offer. to say that any of these unfortunate (nay, tragic) incidents are the result of stupidity of their workforce would be woefully misrepresentative.

the simple fact of the matter is that programs as large as the shuttle aren't just based on some off the shelf cookie cutter science that we can come up with in an afternoon sitting on a message board (not trying to belittle the obvious intelligence that floats through these pages...).

even simple projects such as a 1000 Watt sattelite that does nothing but redirect ground communications to another spot on the planet (often referred to as bent-pipe satellites) can take as much as several hundred million dollars (approaching a billion for a multi-unit system), several hundred engineers and perhaps even 10 years to design and develop. such a program pales in comparison to the magnitude of the shuttle. to say they're even remotely related would serve an injustice to those who have dedicated their ENTIRE CAREERS to this one "little" project.

while it's true they've made glaring errors in the past, very few are the result of bad design or an inability to understand the problem. in the case of the shuttle, it's just plain getting old. also, sometimes the best method for learning what DOES work, is by doing what DOESN'T (unintentionally, of course). we do learn by our mistakes.

often too, problems that seem stupid and easy to solve to armchair scientists are a result of mismanagement. unfortunately, programs that require thousands of people (not just engineers) working in unison present a very real challenge that very few people are capable of handling. given the level of coordination required, mistakes will slip through the cracks. we're only human...

btw, i am not a NASA engineer, but i do work in a related industry and have seen first hand how hard it is to handle the littler problems. every time i watched a shuttle launch (in 7 years living in the area, i saw plenty) i stood in awe at how mere mortals could even come close to accomplishing such a feat. it is truly amazing.

mark

[joema]

#1. Forget about glue. The tiles should not be glued on but clamped on. The tiles should be anchored to the shell of the shuttle not glued on...I am talking about redesigning the back of the tiles so that they have a lip and and indention going all around it and design the bare shell of the shuttle body so that it is equipped with titanium clamps to hold the tiles in place.

The tiles are very brittle and fragile. In contrast the orbiter's aluminum skin bends and flexes under dynamic loads. Ever see the wings of an airliner flex up and down? Something like that.

This basic incompatibility is why the tiles cannot be fastened rigidly to the orbiter. They are actually not glued directly to the skin, but glued to felt strain isolation pads that in turn are glued to the orbiter skin. Similar isolation strips laterally protect tiles from each other. This allows the underlying aluminum skin to flex and bend without cracking and breaking the brittle tiles. It also explains why you can't rigidly fasten tiles with clips, bolts, etc to the orbiter.

-- Joe

[crazy4space]

Being in the construction business I don"t know much about the tiles, however I have had one in my hand thanks to my astronomy club. I do know about 4 years ago all of my insulation manufacturers changed their blowing agents because of the concern for chloro floro carbons (sp) ruining the atmosphere. I have been told that on every launch of the shuttle we used to lose approx. 40 tiles per mission and that now we lose approx. 120 tiles per mission. Wonder if changing the blowing agents for the insulation has anything to do with how well the adhesive sticks to the tiles?
__________________________________________________ __________
My initials are on the moon because Gene Cernan put them there.

[BigJim]

I agree that most tile problems could not be solved easily, but what about having, for extreme emergencies, where we are almost sure there is a fatal problem, a small ablative (Apollo style) capsule launched in the apyload bay or into an accessible orbit? I know this would result in extreme weight penalties, but not nearly as much as more tiles or as difficult as having diagnostic EVAs.

[TinFoilHat]

Adding an escape capsule was considered at one point. It would add so much weight that there would no longer be any point in launching the shuttle anymore.

They've altready got a better system for re-entry. For some of the cancelled shuttle replacement projects a system called ARMOR was developed, which uses an inconel foil oneycomb outer layer, a thick insulation layer in the middle and a titanium skin inner layer. The outer inconel plates overlap like shingles to keep the outer surface sealed even as the airframe heats up and expands, and the connections between the inner and outer layers are through inconel metal brackets which are flexible enough to handle thermal expansion of the outer layer. It's supposed to protect well enough to survive re-entry yet not be so fragile that flying through a thunderstorm destroys it.

There's some more about it here:

http://techreports.larc.nasa.gov/ltr...-2002-0503.pdf

The thing is, it's too late to retrofit this, or any major change, onto the existing shuttles; it's something for the next generation of re-useable spacecraft, if they ever get built.

[daver]

I agree that most tile problems could not be solved easily, but what about having, for extreme emergencies, where we are almost sure there is a fatal problem, a small ablative (Apollo style) capsule launched in the apyload bay or into an accessible orbit? I know this would result in extreme weight penalties, but not nearly as much as more tiles or as difficult as having diagnostic EVAs.

Well, you'd need the diagnostic EVAs to decide whether to use the lifeboat.

I think we guestimated that the weight of an expendable capsule would come to 3 tons or so. That's going to cut into the payload quite a bit. I'm not sure if it is possible to design one that would fit in the payload bay and still return the full crew complement. Having an expendable-launched capsule seems like a reasonable alternative. It shouldn't take more than a couple years to develop (essentially an updated Apollo capsule in the rescue configuration), but it probably would.

[BigJim]

Having an expendable-launched capsule seems like a reasonable alternative. It shouldn't take more than a couple years to develop (essentially an updated Apollo capsule in the rescue configuration), but it probably would

I agree. Perhaps this would be the ideal rescue spacecraft. First, I think the shuttle should be phased out anyway and replaced with the VentureStar, which Dan Goldin brilliantly cancelled. But anyway, I think having an enlarged Apollo-type capsule on a Saturn-IB derived booster on each flight would be more realistic than having a shuttle on the pad on each flight, in case of trouble.

Well, you'd need the diagnostic EVAs to decide whether to use the lifeboat.

Not necessarily. If you had an exterior camera system (does anybody know of any problems with those?) or a major micrometeroid impact, you probably wouldn't need the EVA.

[Bill Thmpson]

I cannot believe that this thread of conversation is still alive like this. I had completely rewritten my ideas of what to say if I was to write a letter to NASA. I have a fresh batch of suggestions that I will be either sending them directly or posting online here.

[gtraz]

Been a reader for a while. This is my first time posting.

An external camera system would be a good idea but hard to manage. There would have to be holes cut into the hull to extend the cameras in orbit and have them retracted during reentry. Seeing the top of the shuttle isn't a problem since there are already cameras on the Canada arm but its seeing the bottom thats tricky. Of course, thats the area of the most interest.

[ToSeek]

Orbital space plane gets additional funding from NASA.

[russ_watters]

Been a reader for a while. This is my first time posting.

An external camera system would be a good idea but hard to manage. There would have to be holes cut into the hull to extend the cameras in orbit and have them retracted during reentry. Seeing the top of the shuttle isn't a problem since there are already cameras on the Canada arm but its seeing the bottom thats tricky. Of course, thats the area of the most interest.

You're in space. There is an easier way. Strap a camera to a remotely piloted MMU. Piece of cake.

[TinFoilHat]

You're in space. There is an easier way. Strap a camera to a remotely piloted MMU. Piece of cake.

The hardware's even been developed and tested. If they'd been carrying this on the last Columbia flight, they could have inspected the entire underside themselves easy.

http://spaceflight.nasa.gov/station/assembly/sprint/

[daver]

You're in space. There is an easier way. Strap a camera to a remotely piloted MMU. Piece of cake.

The hardware's even been developed and tested. If they'd been carrying this on the last Columbia flight, they could have inspected the entire underside themselves easy.

http://spaceflight.nasa.gov/station/assembly/sprint/

Well, that's not everything you'd want. You'd want collision avoidance built in, as well as data storage. The camera seems to be designed to be operated in full view of the operator; you'll need to add some stuff to make it simpler to fly blind. You might want a low-bandwidth channel for it to broadcast position and orientation info if the high-bandwidth video channel is blocked.

I don't see the camera specifics--i'd think you'd want a zoom lens if it doesn't already have one.

The enhancements seem pretty straightforward--i'd think the collision avoidance component would be the hardest to implement.

It would also be nice to fit an autodock mechanism into it, so you wouldn't have to suit up to fly it around.