What technologies need to be developed?

[Valcan]

But if you put the payload outside wouldnt that just increase the amount of drag?

 

[csmyth3025]

But if you put the payload outside wouldn't that just increase the amount of drag?

That is a good question for an aeronautical engineer. If one happens to be reading these posts please feel free to give us your "two cents worth". My guess is that a properly designed mother-ship and orbital vehicle could be matched so as to minimize drag. I believe some of the design simulations and scale testing done by Scaled Composites were aimed at doing this. Burt Rutan is pretty sharp about these kinds of things - if there's a better way, I'm inclined to think he would have taken it since he built both of the White Knight mother-ships from scratch.

I'm not sure how important minimizing drag is for an air launch system. The mother-ship will only be used for relatively short-duration flights up to launch altitude and then return to the space port.

I believe Sir Richard Branson is exploring the possibility of using the White Knight II as a launch platform for LEO insertion of "small" satellites (500 kg or less). There seems to be a big commercial market for this sort of launch capability.

Here, again, I wonder if there's a practical limit to how large an air launch platform can be scaled up and to how large a payload it might be able to deliver to LEO.

Chris

 

[EarthlingX]

I guess that the difference in ISP for jet engines comparing to rocket engines compensates for drag.

 

[csmyth3025]

I guess that the difference in ISP for jet engines comparing to rocket engines compensates for drag.

I'm not sure what you mean. Wikipedia explains the difference in ISP with altitude (air pressure) this way:
"...In rockets, due to atmospheric effects, the specific impulse varies with altitude, reaching a maximum in a vacuum. It is therefore most common to see the specific impulse quoted for the vehicle in a vacuum; the lower sea level values are usually indicated in some way (e.g. 'sl')..."

Wikipedia also provides a chart in their article on atmospheric pressure which indicates that at ~53,000 ft. the pressure is about 1/10 that at sea level.

As I understand it, the main advantages of air launch at ~50,000 ft are as follows:

1) Off-the-shelf air breathing jets can operate at this altitude, thus eliminating the need to carry both oxidizer and fuel
for the mother-ship aircraft -a big weight savings and also a big cost savings.
2) Aircraft can still achieve aerodynamic lift at this altitude, which is more efficient fuel-wise than the current practice of
relying on the brute force of rocket engines to lift the orbital vehicle up through the atmosphere to this altitude.
3) Any forward velocity of the mother-ship in the direction of orbital insertion is a bonus that reduces the necessary
"delta-V" of the orbiter thruster rocket (this is also a weight and cost savings - although, perhaps, minor).
4) The thinner atmosphere a 50,000 ft allows for more efficient thruster rocket performance.
5) Accelerating through the atmosphere at 50,000 ft places a lot less drag - and stress - on the orbiter/thruster
assembly.

I might have missed a few things but this is what I can think of off the top of my head.

Chris

 

[EarthlingX]

Ok, so just from the top of the head, we can check this later in more detail :
- about 1 km/s of delta V to orbit goes to drag when launching vertically
- jet engines have a lot better Isp than rocket engines, they breathe air, no need to carry oxidizer
- main problem with the rocket nozzle is in lower (under 20-30 km) altitude because of the biggest difference in atmosphere pressure, causing non-perfect design of the nozzle (i think i saw Wiki page for that, might have even posted it on the forum)
- lower atmosphere, due to it's thickness, also limits speeds that can be achieved, because of the heating problems

Better Isp is preferable, but in the atmosphere you have to have thrust, or no go. Launching from the carrier, or above the majority of pressure changes does a couple of things:
- more or less uniform pressure (going to 0) above 20/30 km
- much more economical (better Isp) use of fuel, causing lighter craft for the same mass to orbit

I don't know how exactly this plays out when you start messing with the numbers, but i think some of this has been answered here :

A cheap and easy way to space.

I think we are on the same page

 

[EarthlingX]

Here is an example of useful tech:

Antro Unveils a Solar Car That Splits into Two Vehicles!

by Bridgette Meinhold, 02/26/10
Although it’s not particularly known for its autos, Hungary is taking a stab at the electric vehicle market with a futuristic new solar-electric car.

Solar panels go through extreme tests at San Jose lab

February 25, 2010 By Dana Hull

At a nondescript office park in San Jose, solar panels from manufacturers around the world are going through tests of extreme endurance to make sure they are safe to put on your roof.

Near-Frictionless Diamond Material Created Using Nanotechnology

ScienceDaily (Feb. 26, 2010) — Researchers at the University of Pennsylvania, the University of Wisconsin-Madison and IBM Research-Zürich have fabricated an ultra sharp, diamond-like carbon tip possessing such high strength that it is 3,000 times more wear-resistant at the nanoscale than silicon.

Stay tuned:
Latest news and updates ( from List of Multiple Threads on the Same Topic)

 

[nimbus]

Jon Goff's take on this question, from a couple of years ago ('06).
http://selenianboondocks.blogspot.com/2 ... aring.html
At a glance:
Reusable Orbital Transportation

• High Longevity Rocket Engines
  Low-Maintenance Reusable TPS

Aerobraking
On-Orbit Propellant Transfer
Long-Term On-Orbit Propellant Storage
On-Orbit Assembly
On-Orbit Construction
Closing the Water Loop (Or at Least Getting Close)
Extraterrestrial Navigation
Low-Maintenance Space Nuclear Power
Space Tugs
In-Situ Resource Utilization
Artificial Gravity
... In the comments might be a few more. E.G. Better space suits.

 

[EarthlingX]

Jon Goff's take on this question, from a couple of years ago ('06).
http://selenianboondocks.blogspot.com/2 ... aring.html
At a glance:
Reusable Orbital Transportation

• High Longevity Rocket Engines
  Low-Maintenance Reusable TPS

Aerobraking
On-Orbit Propellant Transfer
Long-Term On-Orbit Propellant Storage
On-Orbit Assembly
On-Orbit Construction
Closing the Water Loop (Or at Least Getting Close)
Extraterrestrial Navigation
Low-Maintenance Space Nuclear Power
Space Tugs
In-Situ Resource Utilization
Artificial Gravity
... In the comments might be a few more. E.G. Better space suits.

Thank you.

 

[EarthlingX]

I will start dropping here news, for which i think to be related. This, for example, could be used as a part of a closed-loop system, but it would have to get to space first, i guess :
from Harvard Science
Scientists discover how ocean bacterium turns carbon into fuel

March 11, 2010
Elizabeth Dougherty
Harvard Medical School

Reduce. Reuse. Recycle. We hear this mantra time and again. When it comes to carbon—the "Most Wanted" element in terms of climate change—nature has got reuse and recycle covered. However, it's up to us to reduce. Scientists at Harvard Medical School are trying to meet this challenge by learning more about the carbon cycle, that is, the process by which carbon moves from the atmosphere into plants, oceans, soils, the earth’s crust, and back into the atmosphere again.

One of the biggest movers and shakers is the lowly cyanobacteria, an ocean-dwelling, one-celled organism. Pamela Silver, HMS professor of systems biology, and colleagues have uncovered details about how this bacteria fixes, or digests, carbon. These bacteria build miniature factories inside themselves that turn carbon into fuel.

 

[EarthlingX]

From ScienceDaily :

Compliant Systems: Flexible Yet Strong Materials Allow Aircraft Wings to Flex With Air Flow

ScienceDaily (Mar. 14, 2010) — Those who witnessed the first takeoff of an Airbus A380 Superjumbo from Zurich airport at the end of January know that elegant is not the right word for the aircraft. On the other hand it is perfect to describe a crane as it leaves the ground, rising in a seemingly weightless fashion. This is not just because of the difference in size and weight -- the bird uses its flying surfaces in a completely different manner to the machine. It steers itself by continually varying the geometry of its wings.

An adaptive wing support structure can be constructed using compliant systems. It can be molded in one piece. (Credit: Image courtesy of Empa)

 

[halman]

We have simply GOT to get away from reciprocating internal combustion engines! Between the inefficiency, and the waste products that they produce, they are responsible for much of the problems in generating greenhouse gasses. Gas turbines have the potential to replace practically all recips, as those in aviation call a reciprocating engine. Aviation has embraced turbines extensively, because of their simplicity, reliability, and power. Also, aviation applications do not require torque, which is where turbines fall down.

But we have the technology to overcome that drawback, by using the turbines to power a generator, which can be computer controlled to apply torque very gradually, so that the turbine does not stall. Micro turbines are in use which are only inches in length, yet are able to produce power. Stationary generator sets are being built for backing up electrical grids, because they can be brought on line very quickly, yet are more efficient than diesel gensets.

Continuous combustion is essential to burning cleanly, and only with a turbine do we get continuous combustion in an internal combustion engine. The internal combustion reciprocating engine is a bastardization of the external combustion reciprocating engine, or steam engine, and have never been efficient. But they proved to be the most powerful mobile sources of energy we could develop in the early 1900's, so they became the standard. But we can do better now, and we must.

 

[EarthlingX]

With hybrid vehicles one can design engine with maximum torque over much more narrow part of the RPM curve, avoiding complexity which comes from requirement for constant acceleration. I also think turbines would be very good for such application.

Wankel engine combined with Stirling, would be another alternative.

 

[halman]

With hybrid vehicles one can design engine with maximum torque over much more narrow part of the RPM curve, avoiding complexity which comes from requirement for constant acceleration. I also think turbines would be very good for such application.

Wankel engine combined with Stirling, would be another alternative.

The Wankel, or rotary, engine suffers some of the same drawbacks of the reciprocating engine, in that combustion is momentary, not continuous.

The Stirling engine suffers from the drawback of the pistons having to change their direction of travel constantly, which wastes energy, plus the added complexity of having some external form of energy to provide the heat.

Diesel oil can be burned so cleanly that it can be breathed without any noticeable odor, as the furnaces that my father built proved. They were used to dry hops, the flavoring and preservative agent in beer, and I often times would go into the plenum chamber on a cold night to warm up. There, I was in a room which was being supplied hot air from the furnace, which had a ceiling made of mesh, upon which the hops were spread. (I always made sure that the door would not latch locking me in.) Hops are used in making a product for human consumption, but diesel burned clean enough to be used for drying them, when the combustion was continuous.

Modern turbines can burn their fuel at 97 percent efficiency, or even better, converting that energy into mechanical motion. True, a generator running off of a turbine is no where near as efficient, but it is still far more efficient than a reciprocating engine. And I suspect that that efficiency could be improved with research. Fossil fuels will be used for mobile power production for the foreseeable future, because of their energy density, especially oil. Utilizing it in the most efficient manner is essential.

 

[EarthlingX]

Halman, it is, as usually, very hard to argue against your points

I will keep spamming with various technology flashes, perhaps we find out that some more can be done :

From PhysOrg.com :

Polymer remembers four shapes

March 15, 2010 by Lin Edwards

(PhysOrg.com) -- A new study by General Motors has found that a polymer used commercially in fuel cell membranes can "memorize" four shapes, each assigned to a different temperature. The material could find applications in fields such as space exploration and biomedical engineering.

Quadruple-shape memory properties of PFSA. Visual demonstration. Image credit: Nature.

From AstroBiology Magazine :

Avatars in Space

Posted: 03/15/10
Author: Aaron L. Gronstal

Summary: At this year's Oscars, there was a great deal of buzz surrounding the science fiction epic, Avatar. The movie focuses on human explorers virtually immersing themselves in the environment of a distant world through the eyes and body of an avatar. The movie may be science fiction, but the concepts behind avatars in space exploration are based in science fact.

 

[neutrino78x]

I don't see how you can burn a hydrocarbon "cleanly". Regardless of how you burn it, it will still release CO2 and particulate pollution, right?

--Brian

 

[halman]

I don't see how you can burn a hydrocarbon "cleanly". Regardless of how you burn it, it will still release CO2 and particulate pollution, right?

--Brian

The universal combustion result is water. Carbon dioxide is also commonly released, depending on the substance being oxidized. But particulates are a result of incomplete combustion, not of the combustion process itself. Diesel engines release large quantities of particulates because of the interruption of the combustion process before complete combustion has occurred. The heavy paraffin component in diesel fuel doesn't burn completely, leaving a 'soot'. But, with proper combustion techniques, that does not occur.

In reciprocating gasoline engines, the incomplete combustion results in a complex hydrocarbons being formed, as well as oxides of nitrogen, which are major components in smog.

A technology which needs to be perfected is the beamed transmission of DC electric power.

A technology which needs to be developed is the lifting of water using solar heating. This would allow storage of energy for later use without conversion being done multiple times. Even 30 feet would produce enough head to run a turbine.

Energy storage in general is a ripe field for innovation.

Practically all of of our energy conversion technologies rely on large differences between states, while biologic processes accomplish the same things without high temperatures, differentials in potential, or ranges of chemical states. We could achieve far greater efficiency by emulating simple processes used widely in nature.

 

[EarthlingX]

A technology which needs to be perfected is the beamed transmission of DC electric power.

What's wrong with AC ? or MASER ? I can think of at least a couple more better ways than Direct Current ..

A technology which needs to be developed is the lifting of water using solar heating. This would allow storage of energy for later use without conversion being done multiple times. Even 30 feet would produce enough head to run a turbine.

Or something else with the same effect.

Energy storage in general is a ripe field for innovation.

Practically all of of our energy conversion technologies rely on large differences between states, while biologic processes accomplish the same things without high temperatures, differentials in potential, or ranges of chemical states. We could achieve far greater efficiency by emulating simple processes used widely in nature.

I will drop a couple of those here too.

 

[MeteorWayne]

We have simply GOT to get away from reciprocating internal combustion engines! .

WTH does that have to do with the Airbus???

 

[halman]

We have simply GOT to get away from reciprocating internal combustion engines! .

WTH does that have to do with the Airbus???

Absolutely nothing. The topic of this forum is technologies, and internal combustion reciprocating engines are the most widely used technology in mobile power plants. I was making a statement regarding a need for a technology to supplant the screwed over steam engine that ended up in practically every car in the United States.

 

[neutrino78x]

The universal combustion result is water. Carbon dioxide is also commonly released, depending on the substance being oxidized.

Yeah, see, if you are burning a hydrocarbon, you get pollution, always. Hence, we should only burn Hydrogen and Oxygen.

see this forum thread.

--Brian

 

[3DX]

I think it must be new methods of propulsion, non rocket methods, of course.
According to that material humankind will have some breakthrough in this direction:

http://ias-spes.org/IASSPES_New/Papers/DRS21stC%20.pdf

Possibly it will look like this: http://z15xcvb.narod.ru/device_engl.htm
May be such devices will change sometime jet engines. Also I hope that Nuclear Jet Engines won’t have any future. Quit obviously that it’ll be a flying Chernobyl.

 

[scottb50]

Continuous combustion is essential to burning cleanly, and only with a turbine do we get continuous combustion in an internal combustion engine. The internal combustion reciprocating engine is a bastardization of the external combustion reciprocating engine, or steam engine, and have never been efficient. But they proved to be the most powerful mobile sources of energy we could develop in the early 1900's, so they became the standard. But we can do better now, and we must.

That was Bill Lear's thinking but he couldn't get it to work. Electric motors are much more efficient and torque is their middle name. A breadbox sized steam powered generator that could power a Tesla for 200 miles on a gallon of French fry oil.

 

[Yuri_Armstrong]

A "mars ferry", built in orbit and meant to stay in space instead of landing, would be a great idea as the OP suggested. A genuine spaceship that does not have to deal with atmosphere and gravity. We could use the Orion craft to dock with the mothership that could bring them to Mars.

 

[scottb50]

Reusable Orbital Transportation.
Done that

High Longevity Rocket Engines.
Getting better

Low-Maintenance Reusable TPS.
The X whatever is expected to relaunch soon after returning so progress has been made

On-Orbit Propellant Transfer.
No different then Oxygen, Nitrogen, water or anything else

Long-Term On-Orbit Propellant Storage
If you use water exclusively, there is plenty of experience. Asteroids have been photographed with ice that is probably water.

On-Orbit Assembly
I am convinced, by Skylab, MIR and ISS that it is a non-issue.

On-Orbit Construction.
Sounds like the last point.

Closing the Water Loop (Or at Least Getting Close).
See the reply above.

Extraterrestrial Navigation.
That hasn't presented a lot of problems.

Low-Maintenance Space Nuclear Power.
Why bother when there is a 24-7 supply of Solar, except in orbit.

Space Tugs.
Probably the most important. Reduced cost of Platforms and an exponential explosion of applications would be possible. Capabilities could be upgraded as needed. Platforms could be moved, re-fitted, upgraded or added to as needed and individual transponders could be replaced or upgraded as needed. Five Platforms could cover the Earth.

In-Situ Resource Utilization.
Got to get there before we can do that.

Artificial Gravity.

Would be nice, but not a show stopper.
... In the comments might be a few more. E.G. Better space suits.

 

[Yuri_Armstrong]

Artifical gravity would be convenient. It may be though, that propulsion technology advances to the point where artifical gravity is not really necessary or cost effective. On a 2 month mission to Mars, is artifical gravity really necessary? I don't think so. It is especially unnecessary for moon trips. Besides, zero-g is fun