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Posted on: A cheap and easy way to space.
at 11/21/2009 6:48pm

Basically, what I am proposing to do is to lift the launch pad to about 50,000 feet. By doing so, whatever we launch ... more(+)

Basically, what I am proposing to do is to lift the launch pad to about 50,000 feet. By doing so, whatever we launch is going to be able to use all of its fuel for accelerating, without wasting half of it just fighting gravity. This is what makes our launch vehicles today so large in comparison to the payloads they can lift to orbit, having to fight gravity until they can reach an altitude where the air density is low enough that they can begin to accelerate with the full power of their engines.

The carrier wing has nothing to do with accelerating the spacecraft, it just lifts it through the densest part of the atmosphere, by using that atmosphere for lift and to provide oxidizer for its engines. The catapult is simply a way to accelerate the carrier wing and its payload to takeoff velocity quickly, and without having to use a lot of the fuel of the carrier wing.

Another goal of this launch system is to make it possible to launch in conditions which are less than perfect, and without having large numbers of people monitoring every aspect of the launch vehicle, each with the ability to postpone or cancel a launch. Think of an airliner departing on a journey, which will occur in practically any conditions. This is the kind of utility we need in a space access system.

Instead of using the most advanced technology available, the highest performance fuels, the most radical designs, this system would be as simple, robust, and reliable as we can make it. After we get our costs per mass unit to orbit down, we can begin experimenting with different engines, nozzle types, and so on. But we already know how to build rocket engines which burn kerosene and liquid oxygen efficiently, while providing lots of thrust. We have learned how to build turbo pumps which will supply those engines with enough fuel for continuous operation, cooling strategies which will prevent those engines from melting, and so on down the list.

There is nothing new in this proposal, except for launching from the back of an aircraft, which I am confident we could master. The wing will be larger than any that we have ever built, but there are no fundamental limits to the size of a wing. It just means more power to overcome the drag.

Until we have a system which can provide access to orbit on a regular basis, cheaply, reliably, and safely, progress in space exploration is going to be limited, and large scale investment by the private sector is going to be scarce. It is that investment by the private sector which is the key to our future, because only that will insure that we will continue to expand our sphere of activities beyond this planet. close(-)

Posted on: An idea to re-ignite public passion for space
at 11/07/2009 7:49am

missionunknown,

In my opinion, the only thing that is going to get people interested in space exploration again is to ... more(+)

missionunknown,

In my opinion, the only thing that is going to get people interested in space exploration again is to get operations going on the moon. That is the only place in space that the average person can understand and recognize. Mars is just a point of light in the sky, no different than Sirius, as far as the man on the street is concerned. Orbital operations don’t click with people, even though the International Space Station is quite obvious when it passes by.

Knowing that there are people up there on the Moon, living and working, would have a profound effect on most people’s viewpoint, I believe. They would have to confront the concept that there is someplace other than ‘here’, meaning the Earth, which is the natural way of thinking. Once they get their mind around the idea that there is some where other than ‘here’, that would force them to accept that ‘here’ is not an infinite size, and can be used up.

We are dealing with a public which does not even realize that the Sun is a star, that considers sporting activities to be the most important thing in the world, unless it is some celebrity doing something stupid. People who have no concept of what the Solar System is, who probably believe that the Sun rotates around the Earth. There is only one goal in space which they can understand, only one place in space that they can find without assistance, and that is the Moon. It doesn’t matter why we are going there, or what we will do there, just that there will be people up there.

Once we wake people up with the idea that people are going to the Moon, interest will soar. Education will become more important, technology will be more than just cell phones and iPods, and our horizons will start to expand. Right now, every launch could be for a mission going to Aldebaran, for all the typical citizen knows. Low Earth Orbit is equivalent to Andromeda to many people. Give them something that they can understand, that they can see with their own eyes, and you might get them interested. close(-)

Posted on: Asteroid mining-delivering the goods without mass ...
at 11/07/2009 7:25am

Crossover_Maniac,

The concept of asteroid mining is based on the premise that we will have the industrial capacity ... more(+)

Crossover_Maniac,

The concept of asteroid mining is based on the premise that we will have the industrial capacity off-planet to utilize the materials we harvest from the asteroids. So dropping payloads of raw materials into the atmosphere is not very likely. What will be coming down will be using the atmosphere to slow down, and parachutes to lower the landing speed to acceptable levels. Most likely, what will be coming down will be processed metals, already cast into parts ready for assembly.

HopDavid,

Have you ever considered what impact carbon costs will have on industrial processing and mineral extraction here on Earth? It is quite likely that we are not going to be able to mine ore, smelt it down, and cast it here much longer, which will make any competing source cheaper than what we can produce here. Costs are subject to supply and demand. It used to be that hardwoods for furniture construction were readily available. Try finding large, clear pieces of hardwood today. Or consider crude oil: 75 years ago, most wells were less than 1000 feet deep. Today, we are drilling in thousands of feet of water, and going over a mile beneath the sea floor to reach oil deposits. A new field off of the coast of Brazil is being explored for exploitation, which will require drilling in 10,000 feet of water, and going nearly 3 miles beneath the ocean floor, through a layer of salt several thousand feet thick. We will never run out of crude oil, but we will probably not be able to use it for something as mundane as fuel after a while.

Environmental costs have only begun to be a factor in our technologically based culture, but they are threatening to increase at a rapid rate. We may soon face a choice of killing ourselves to maintain our technology, or moving it off planet. close(-)

Posted on: A cheap and easy way to space.
at 11/02/2009 5:34am

scottb50,

You are correct, the White Knight II does used four engines.

The Solid Rocket Boosters are jettisoned at ... more(+)

scottb50,

You are correct, the White Knight II does used four engines.

The Solid Rocket Boosters are jettisoned at about 150,000 feet, not 250,000.

In my concept, the fully fueled orbiter would weigh about 500,000 pounds. Take off weight of the stack would be around 1.3 million pounds. Maximum take off weight of the C-5 is 840,000 pounds. We should be able to do better than that. close(-)

Posted on: A cheap and easy way to space.
at 10/28/2009 8:13pm

scottb50,

As it was originally conceived, the Space Shuttle was not to be a heavy-lift launch vehicle. Only ... more(+)

scottb50,

As it was originally conceived, the Space Shuttle was not to be a heavy-lift launch vehicle. Only compliance with Air Force payload requirements made it such. Budget restrictions caused left-over Apollo hardware to be put back in service for transporting the stack to the launch site, not the desires of the engineers. What is flying now is a massive compromise, which is exactly what we should avoid.

Launching straight up means using tremendous amounts of energy, which requires the utmost in performance, absolutely perfect conditions, and very few abort options. By the time the Space Shuttle separates from the Solid Rocket Boosters, it has burned nearly half of the fuel in the External Tank, yet the vehicle is only traveling about 1 mile per second. Over 3 million pounds of the 4.5 million at launch have been discarded at that point, and 4 miles per second still must be added to the vehicle's velocity.

The speed of the orbiter at separation in my concept is inconsequential, because the orbiter is at an altitude where it can use nearly all of it's energy to accelerate, instead of expending 50 percent or more just fighting gravity. If the orbiter can reach 5 miles per second from a standing start at 50,000 feet, what difference does it make if it going 200 miles per hour or 500 miles per hour? We have to stop thinking in terms of a vertical launch, where each stage must add as much velocity as possible. The first stage, the carrier wing, is required only to lift the orbiter to an altitude where it can accelerate as rapidly as possible, not to impart velocity to the orbiter.

Until the White Knight came along, we had never seen an aircraft designed specifically for lifting mass. Every air-launch system up to that time used an existing airframe. The White Knight II still only uses two engines, in spite of the larger payload it is to carry. Burt Rutan made a remark back when Space Ship One was flying about a carrier wing with eight 747-size engines. That is the kind of power that is needed to lift large payloads to launch altitude.

Using a catapult to launch the stack has two advantages: The wing does not have to have an undercarriage capable of supporting over 1 million pounds, and a runway 15 miles long does not have to be built. Getting the stack up to take-off velocity using just the onboard engines would take a long time, and an engine failure would mean having enough runway to safely stop after reaching 99 percent of take-off speed. The catapult would support the stack, accelerate it fairly quickly, and provide a means of slowing it down in case of an abort. close(-)

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