New Mars Forums

Official discussion forum of The Mars Society and MarsNews.com

You are not logged in.

Announcement

Announcement: We've recently made changes to our user database and have removed inactive and spam users. If you can not login, please re-register.

#1 2006-03-23 12:12:40

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,037

Re: TPS and RLV

It is well understood that to keep getting to space low in cost not being of an expensive design is just one of the must do's but this is also a two fold problem because usually being cheap means fragile, Expendable at a more durable construction means cost and finally being able to re-use at this point means glassy or ceramic tiled.

Andrews Space, Inc. Wins Contract to Study Flexible Transpiration Cooled TPS Concepts for Ballute Re-Entry Capabilities

Phase I contract from NASA Dryden Flight Research Center (DFRC) to perform a study entitled "Flexible Transpiration Cooled Thermal Protection Systems (TPS) for Inflatable Atmospheric Capture & Entry Systems

There has been this topic mentioned in another thread but it was quite a while ago.

Offline

#2 2006-03-23 19:09:09

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: TPS and RLV

If we are ever going to make a viable, true RLV that really takes advantage of reuseability, then an expendable heat shield is not an option, and thats all there is to it. Metal heat shields, improved ceramics, transpirational cooling, whatever - but it can't be expendable.

Transpirational cooling could be a sort of middle ground between an active (coolant pumped through the skin) and passive (metal/glass/ceramic) heat shield, but it has the problem of the weight of all that liquid coolant. I'm also curious what happens to the heat shield if you use water, since in space it will freeze and form ice which will expand inside the material, or boil off and dry out so you burn up.

In the long run, we are just going to have to learn to make better rockets or jet engines and live with the weight of a reuseable heat shield.


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

Offline

#3 2006-10-09 18:47:33

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,037

Re: TPS and RLV

PHASE II CONTRACT TO STUDY FLEXIBLE TRANSPIRATION COOLED TPS CONCEPTS FOR BALLUTE RE-ENTRY CAPABILITIES AWARDED TO ANDREWS SPACE, INC

Andrews Space, Inc. (Andrews) announced today that it has been awarded a $600,000 Small Business Innovative Research (SBIR) Phase II contract from NASA Dryden Flight Research Center (DFRC) to perform a study entitled “Flexible Transpiration Cooled Thermal Protection Systems (TPS) for Inflatable Atmospheric Capture & Entry Systems”.  These concepts are directly applicable to ballute technologies, which Andrews is in the process of developing.  The contract is an extension of the Phase I study Andrews completed in July 2006.

Offline

#4 2006-10-09 23:28:52

cIclops
Member
Registered: 2005-06-16
Posts: 3,230

Re: TPS and RLV

If we are ever going to make a viable, true RLV that really takes advantage of reuseability, then an expendable heat shield is not an option, and thats all there is to it. Metal heat shields, improved ceramics, transpirational cooling, whatever - but it can't be expendable.

Obviously, by definition a "true RLV" can't have any expendable components. Yet a viable, that is affordable and practical, RLV may require that one additional expendable element, an expendable TPS. What if a TPS can be designed to be replaced as easily as the hybrid motor on Spaceship 2? Or better still, as quickly as say the tyres on a Formula 1 car? Is a F1 car not reusable because it requires three sets of tyres for one race?

Did sailing ship owners refuse to buy steam ships because they required expendable fuel?


Let's go to Mars and far beyond -  triple NASA's budget !   #space channel !!    - videos !!!

Offline

#5 2006-10-10 06:13:52

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: TPS and RLV

There is no such thing as an "easy" heat shield, if the shield is only in a few pieces then each piece will have to be both large and without defect plus probably a complex shape, making it expensive to build even if its cheap to install (which I doubt, given the high minimum reliability). If the shield is in smaller parts, you get the same problem as the Shuttle glass tiles, albeit to a lesser degree.

It is absolutely imperative that the shield be at least somewhat reuseable (say, 10-15 flights), its just got to be that way, no other way makes any sense. An RLV is going to be an expensive project, and the only justification for that expense is an order of magnetude decrease in operational costs, and the heat shield threatens to be one of the biggest expenses. Whoever builds the thing has to come through, they can't make it only somewhat or incrimentally cheaper to fly, its got to be rule changing cheap. Unless an expendable and cheap heat shield were a "sure thing," then a reuseable one is the only choice.

I reject this analogy with sailing ships and sails too, thats nonsense. A better one would be having to replace, say, the deck every time you went to sea.


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

Offline

#6 2006-10-10 11:29:19

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: TPS and RLV

Space Elevators don't require any heat shield. I've given the whole concept of a resuable spaceship that flies into space almost 40 years of my life, and nothing useful has ever come out of this pursuit. A truly reusable space vehicle would be something that stays on the ground and sends things up rather that goes into orbit itself. One idea of a reusable space vehicle is a factory that builds expendible space vehicles cheaply. Have a standardized model of expendible rocket and have the factory mass produce them with a high degree of automation. One of the reasons expendible rockets are so expensive is because they are hand-built, if you can get rid of the hands yet still build the rockets, you have a cheaper launch system.

Offline

#7 2006-10-10 13:09:16

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: TPS and RLV

Space elevators, as cool as they could be, still are quite likely impossible. It is entirely possible that carbon nanofiber composites will never reach the require strength. Even if they do reacht the "magic number," we will require several hundreds of tonnes of the stuff, if not a few thousand. Right now producing such a quantity isn't going to happen, and companies are scaling up to produce only kilogram amounts.

Long story short, even if it can be done, its going to take a long time. Furthermore, unless the cable will last a while, then you will have to be launching lots of materials to make the elevator worthwhile in the first place, since if it wears or breaks too often then you won't be getting anywhere anyway. I bet that the initial "shake out the bugs" period will not be trivial either.

As far as why little has come from RLV research thus far, is because nobody has really needed one to date. Other than the half-hearted Regan era "Star Wars" anti-missile initative and some unrealistic NASA dreaming, nobody has really gotten into anything that you would need a real RLV. Building ICBMs to threaten the Commies to prevent nuclear destruction was much cheaper and the dinky zero-gravity research or the non-exsistant "phantom" launch market NASA wanted could never justify the flight rate. VentureStar, DC-X, and so on have been understandably half-hearted, since even if they were built, they would spend most of their time on the ground doing nothing.

A reuseable vehicle is possible, it honestly really is, but it would be expensive to develop and build. We have not really flexed the muscle of modern aerospace technology as far as airplanes go since thus far there hasn't been a good reason to. With the advent of stealth, low-observables cruise missiles and ballistic missiles the USAF hasn't needed a superhigh performance bomber. Civil aviation can't justify superhigh performance air liners either, hence sticking with high-efficiency subsonic air liners. The reason there are no large high-performance aircraft is since they are unessesarry, not because there are impossible.

If you use a high-performance carrier plane, then the upper stage vehicle gets quite a bit smaller; the SR-71 of ages past could in theory reach about Mach 3.5 with airbreathing ramjets and was made exclusively of metal, particularly titanium. If we could do that back then fifty years ago, predating practical onboard digital computers, high-temperature engine & skin materials, I think it is practical to make a sizeable aircraft able to reach low hypersonic speeds (say Mach 5) powerd by advanced jets spiked with water/LOX or rockets for sprinting.

With this carrier plane, then an all-rocket upper stage of useful size really begins to shrink. Cryogenic engine technology hasn't completly fizzled out since the SSME, and engines with the required performance and reliability are very practical and could be built without excessive difficulty. The upper stage burning Hydrogen only with such an engine and built from composite materials would do the trick, resulting in really decent double-digit payload fractions.

We could do this, right now today, with some willpower and money, and infact barring a space elevator it will have to be done eventually.

Expendable rockets could probably be made several times cheaper if they were mass-produced, but still not the order(s) of magnetude required to really make the difference, if for no other reason then you have to build a new rocket every time you fly. Simple as that.

I don't think regular ballistic rockets or capsules will ever be practical for medium-to-large scale human travel either, that to set up an industrially signifigant Lunar mine or anything more than a small research base on Mars will require something with more reliability and volume than a rocket can give you. A spaceplane has inherint kinetic advantages over rockets & capsules, plus the advantage of more practical volume.


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

Offline

#8 2006-10-11 11:14:40

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: TPS and RLV

Space elevators, as cool as they could be, still are quite likely impossible. It is entirely possible that carbon nanofiber composites will never reach the require strength. Even if they do reacht the "magic number," we will require several hundreds of tonnes of the stuff, if not a few thousand. Right now producing such a quantity isn't going to happen, and companies are scaling up to produce only kilogram amounts.

Long story short, even if it can be done, its going to take a long time. Furthermore, unless the cable will last a while, then you will have to be launching lots of materials to make the elevator worthwhile in the first place, since if it wears or breaks too often then you won't be getting anywhere anyway. I bet that the initial "shake out the bugs" period will not be trivial either.

As far as why little has come from RLV research thus far, is because nobody has really needed one to date. Other than the half-hearted Regan era "Star Wars" anti-missile initative and some unrealistic NASA dreaming, nobody has really gotten into anything that you would need a real RLV. Building ICBMs to threaten the Commies to prevent nuclear destruction was much cheaper and the dinky zero-gravity research or the non-exsistant "phantom" launch market NASA wanted could never justify the flight rate. VentureStar, DC-X, and so on have been understandably half-hearted, since even if they were built, they would spend most of their time on the ground doing nothing.

We certainly need one to get into space in a big way. A lot of the world's problems would be solved if we could travel into space cheaply, so in a sense we do need this stuff, and what we got now is not sufficient. The reusable launch vehicle efforts were mismanaged because they were imcompetantly managed government programs, with no real incentives to accomplish anything, as the system was non compedative. NASA can certainly create a launch market if it spent its money wisely, and incentivized private companies to do the development work by lowering the bar of profitability. If we spend the money, we don't want to waste it on dead ends, and inefficient buerocracy. I say we let the private companies develop their own buerocracy, and manage their own programs to accomplish the goals NASA sets forth, rather than NASA running the program itself. Government programs are essentially jobs programs, and survival is not at issue as it would be in a private corporation competing with others. That is why I think the prize system is a more efficient and productive expediture of government funds rather than a buerocracy with rules and regs, and cushy union jobs and bloat.

Offline

#9 2006-10-11 17:52:55

Grypd
Member
From: Scotland, Europe
Registered: 2004-06-07
Posts: 1,847

Re: TPS and RLV

Tom the problem is that there is no incentive to create a TSTO reusable space system and that is simply down to the economic equation. Space has a lot of satelites but they last a long time and so the launch market as is meets the need for the satelite owners. The RLV programmes have all been either paper exercises or if prototypes actually built research projects with no real intention to build the things. There is also no incentive to build a space elevator what would it service?

No private company will build something unless there appears to be a need and that would have to come from goverment. And currently the goverment does not have that need.

If we could change this by either finding a financial benefit that improves radically with cheap access to the point it makes sense then private companies will spend there profits to design and build RLVs.

Until then we are reliant on Goverment and there plans and it is politics that matter there.


Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.

Offline

#10 2006-10-12 13:10:06

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: TPS and RLV

We certainly need one to get into space in a big way. A lot of the world's problems would be solved if we could travel into space cheaply, so in a sense we do need this stuff, and what we got now is not sufficient. The reusable launch vehicle efforts were mismanaged because they were imcompetantly managed government programs, with no real incentives to accomplish anything, as the system was non compedative. NASA can certainly create a launch market if it spent its money wisely, and incentivized private companies to do the development work by lowering the bar of profitability. If we spend the money, we don't want to waste it on dead ends, and inefficient buerocracy. I say we let the private companies develop their own buerocracy, and manage their own programs to accomplish the goals NASA sets forth, rather than NASA running the program itself. Government programs are essentially jobs programs, and survival is not at issue as it would be in a private corporation competing with others. That is why I think the prize system is a more efficient and productive expediture of government funds rather than a buerocracy with rules and regs, and cushy union jobs and bloat.

Really? Why do we "need" to get into space in a big way? I certainly think that it is a good idea, but why do we need to? Or, at the very least, what reason would you give to the general public that would convince them? They will, ultimately, be paying for it so what will they be getting for their money? Its just so hard to do anything in space beyond limited exploration, that you have got to have a really good reason.

And again with the whole "oh if only there was competition" bit, but with no market for launch to speak of then there is no good reason for there to be much competition. When only a handfull of companies can provide all the launch that everybody in the whole world needs and then some, there really isn't much room for upstarts.

NASA can't generate a launch market out of thin air, or at least not alot of one; with the Ares series of rockets and existing manufacturing and launch facilities, NASA ought to be able to explore the Moon and Mars and set up research stations/fuel depots there, no RLV's required. This ought to keep NASA busy until 2050 or so no problem.

There is no great untapped launch market and won't be for a while, so there is no need for an RLV, which is why nobody has really been serious about building one and the government isn't going to pay for it, not the expense required to make a true RLV anyway.

Your dogmatic beliefe in prize systems is silly, the risk that the project will fail or cost more than the prize is worth or somebody else will beat you to the purse simply makes the kind of multibillion dollar, multiyear commitment to such a project insane. Investors are extremely cautious and parinoid about where that size of money goes, and unless a return is pretty much assured, there are better places to put their money. And, as a rule, when there are better places to put money of that magnetude, the money will go there.

A prize system can work when the competitors either won't lose much if they fail to win, or else they have some other motive than financial profit (eg AltSpace nuts who "want to do (insert thing here)"). These people simply do not control billion-dollar sums of money or huge aerospace companies, not by two or three orders of magnetude, and so a prize system for a large task is fundimentally different than one for a small project.


"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw

The glass is at 50% of capacity

Offline

#11 2006-10-13 19:58:56

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,037

Re: TPS and RLV

Here is another alternative way to getting thermal protection.
NASA to test space airbags

NASA is investing $600,000 in developing giant airbags that could one day replace traditional heat-shielding for spacecraft entering the Earth's atmosphere.

The idea is that inflatable "ballutes" (somewhere between a balloon and a parachute) will make a good, lightweight, alternative to either permanent or ablative heat shields.

In theory, the ballute would be inflated with pressurised gas just before re-entry. The design NASA is funding, developed by Andrews Space in Seattle, relies on the ballute allowing some of its gas to escape, providing a buffer between the atmosphere and the ballute material.

As the craft plunges through the atmosphere, the escaping gas would be heated up and carry the heat away from the shield, helping to keep it and the craft cool through the raging heat of re-entry.

I believe the russians have been working on this as well.

Offline

#12 2006-12-20 21:29:06

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,037

Re: TPS and RLV

NASA Meets Key Objective In Developing New Propulsion Method

art-concept-aerocapture-orbit-mars-bg.jpg

Ship Aerobreaking


The tests were conducted at the Sandia National Laboratories in Albuquerque, N.M. Located on Kirtland Air Force base, Sandia's National Solar Thermal Test Facility is a nine-acre test site with a 200-foot-tall solar tower, 212 computer-controlled mirrors called heliostats and a separate five-story control tower.

The heliostats harness the power of the sun and direct it to a test sample mounted on top of the solar tower. With the total mirror area exceeding 84,000 square feet, the facility can subject specimens to up to 260 watts of thermal energy per square centimeter -- about 2,600 times the intensity of the sun on Earth.

The tests focused on a type of spacecraft shielding material called an advanced charring ablator.

"The tests exposed ablators to solar power levels up to 150 watts per square centimeter -- approximately 1,500 times the intensity of the sun on Earth on a clear day,

Offline

#13 2006-12-22 16:11:36

publiusr
Member
From: Alabama
Registered: 2005-02-24
Posts: 682

Re: TPS and RLV

I don't call that propulsion exactly.

Offline

#14 2006-12-28 20:47:55

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,037

Re: TPS and RLV

This is great stuff as it applies to the question of the topic.

"Status of metallic foam/foil heat shields?": developed and already obsolete. A metallic heat shield was developed that uses titanium plate on the inside toward the aircraft skin, inconel 617 plate outside that contacts high temperature air, titanium bolt stand-offs to hold them apart, and crinkled inconel 617 foil between. It works but it's heavy and has limited heat protection; it only protects against 2000°F.
X-33's Innovative Metallic Thermal Shield 'Ready for Flight'

A more advanced heat shield is DurAFRSI: Durable Advanced Flexible Reuseable Surface Insulation. It's a thermal quilt with Nextel 440 cloth, Saffil fibre batting inside, cloth folded over to form two layers of cloth on the bottom next to aircraft skin, quilted with threads of Nextel 440, Inconel 617 mesh screen on top sewn to the Nextel 440 fabric with Nextel 440 thread, and finally Inconel 617 foil brazed onto the screen. The screen is 0.003" thick, foil is 0.002" thick. Quilting threads are 1/4" apart, and the folded fabric on the back covers the quilting threads. They use standard brazing compound, not anything fancy. This provides a metal foil skin for air flow. It protects against 2000°F, same as metal tiles but lighter.

Reinforced Carbon-Carbon (RCC) works just fine for leading edges as long as you don't impact it with debris at hypersonic speed. Solution: don't shed debris.

If the fancy fabric heat shield and RCC panels work well enough for the vehicle, then that sounds all right (esp. for TSTO space planes). But I am unconvinced that they or present refractory materials are good enough for a Scramjet vehicle, so regenerative cooling could be a necessity. It can't have an ablative shield since those aren't reusable, which is a must for an SSTO.

Offline

#15 2006-12-28 21:14:48

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,037

Re: TPS and RLV

While the Orion is meant to reuseable for up to 10 times.

Lockheed and NASA agree Orion changes

The number of parachutes, retro-rocket location, heatshield structure and use of crushable zones have all been agreed between the US space agency and Lockheed.

NASA and Lockheed have agreed to have three parachutes, not four to locate the retro-rockets behind the thermal protection system (TPS) heatshield, not in the parachute shrouds as Lockheed had proposed, with the shield being dropped just before landing to allow retro-rocket firing to segment the shield instead of using a monolithic structure and use Lockheed's choice of TPS material, phenolic impregnated carbon ablator (PICA). The Orion capsule will also have a crushable zone on its underside.

"As we drop the heatshield, we can take some area out of the parachutes and that saves weight,"

Here is another of the contracts that have been awarded.

NASA Awards Thermal Protection Contract for Orion Spacecraft to Boeing

The present Phase II contract with Boeing is a continuation of an earlier Phase I NASA effort that evaluated phenolic impregnated carbon ablator (PICA), as well as four other candidate materials using extensive testing and analysis. Boeing has been selected to provide PICA, a proprietary material manufactured by its subcontractor, Fiber Materials Inc. of Biddeford, Maine, for continued testing and evaluation.

Went to see the FMI plant and was shown the area where the PICA shield material as it was being made. There is a limiting factor in the treatment of the raw material in that the chamber for the process makes a bilet (large brick) about 18 inches by 3 feet by about a foot thick. The carbon is impregnated with yellow phenolic in solution that then is baked out to leave the brick.

This granted is in the developement stages and still under developement for the very large Orion versus its previous use on StarDust.

Offline

#16 2007-01-27 12:17:27

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,037

Re: TPS and RLV

NASA Studies Early Moon Shot for New Space Capsule

With skip entry you get a lot more variability on that launch window. You get it to the point where you can basically go home any day you want.
while skip entry promises tremendous operational capabilities, he said, it creates interesting technical challenges for to the thermal protection system as well as control and guidance.


NASA is designing an ablative heat shield for Orion that will be scrapped and replaced after each flight. Skimming the atmosphere before plunging in creates unique thermal stresses that NASA does not fully understand, and that could drive the agency to build more robustness than necessary into the heat shield.


There is some risk associated with how well the thermal protection system will work, Horowitz said. If you can put some of that risk to bed early with a high-velocity test and proper instrumentation on board and you can look at it after you get it back, before you go into production you may be able to knock a couple hundred pounds off because you say, ‘hey, my unknowns are smaller, therefore I can shave of an inch of thermal protection system because I don’t have to protect for unknowns because its not unknown any more.


I guess another term for aerobraking

Offline

#17 2007-01-27 15:38:14

RedStreak
Member
From: Illinois
Registered: 2006-05-12
Posts: 541

Re: TPS and RLV

Space elevators, as cool as they could be, still are quite likely impossible. It is entirely possible that carbon nanofiber composites will never reach the require strength. Even if they do reacht the "magic number," we will require several hundreds of tonnes of the stuff, if not a few thousand. Right now producing such a quantity isn't going to happen, and companies are scaling up to produce only kilogram amounts.

I have a little hope for space elevators but right now they're barely at an experimental stage let alone out of hypothetical.  If you're optimistic bet on 2050, realistic maybe 2120, and pessemistic never.

Offline

#18 2007-01-27 15:42:57

RedStreak
Member
From: Illinois
Registered: 2006-05-12
Posts: 541

Re: TPS and RLV

With skip entry you get a lot more variability on that launch window.


I guess another term for aerobraking

If it isn't aerobraking it is a close match.  I think the difference would be if the aforementioned skip puts the spacecraft into LEO from a high-speed transLunar trajectory.  Certainly the same engineering could be applicable to aerobraking at Mars or even Venus or even the outer planets (for a mission to the Galilean satellites, for instance, it would be more mass-conservative to aerobrake at Jupiter ala 2010 Odessey Two).

Offline

#19 2017-01-15 09:59:08

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,037

Re: TPS and RLV

It looks like Space X has answered this question for at least a first stage and for the capsule, Of Thermal Protection System and Reuseable Launch Vehicle.....

Offline

#20 2018-12-25 09:01:06

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,037

Re: TPS and RLV

As you can see we have talked about what is important in order to make a reusuable launch vehicle possible and that is the heat shielding.

Offline

Board footer

Powered by FluxBB