Final Project

Max M.

Legislator:  Rick Green, Representative

(Click on image above to enlarge.)

For my final assignment, I decided to go back to unit one, and discuss the current space shuttle and my design for a future shuttle. I am extremely interested in the Mars colony, the space station, the moon, and almost every other subject I have covered this year, but none of it is possible until we have a cheap, efficient way of escaping Earth's atmosphere. Currently, I believe this is the most important goal for NASA, and any other countries or private companies who want to embark on the task. The creation of an easy, quick, and cheap way of getting to space is imperative, and would greatly accelerate all other future advancements in space exploration, and the technology and knowledge to arise from it. What I find disturbing is that we have the means today to make space flight easier, but we are still relying on the shuttle to get us there. There is of course, nothing wrong with the shuttle. It is a proven, safe technology, but it is old, outdated and most of all, ridiculously expensive to launch. It requires hundreds of man-hours, and weeks of planning just to get the shuttle off of the ground. I am looking forward to a day when space flight can become as routine as commercial flights. I hope that someday we will design a shuttle that will come off the assembly line as often as a commercial jetliner; a shuttle that is easy to fly, extremely versatile, and cheap enough so that private companies could make a profit off of it. Only then will the space age truly take-off and develop into what it should be. NASA has made all of the most important breakthroughs in space technology and exploration up to this point. But when we get private investors and individual explorers in space, the possibilities are endless. Upon researching the shuttle, I found it to be an extremely advanced and ingenious machine. My design includes most of the same basic concepts, but includes some major and minor changes I would make to the design.

I have attempted to design a shuttle advanced enough and versatile enough to revolutionize space exploration. I have also tried, as in all of my designs up until now, to rely as much as possible on proven technologies that will still work in this situation. This craft is designed so that it would park at a passenger terminal in any airport around the world, and with clearance from the local tower, it could embark on a journey to take its passengers to the space station or beyond. Maybe even to the moon. This shuttle could also be used, with some variations, to possibly perform the same task on the planet Mars. This in direct contrast with the current shuttle, which requires millions of dollars and hundreds of people to make a launch possible. And even then, it can only be used for specific tasks within Earthıs orbit.

The basic design of my shuttle is a sort of hybrid of the current space shuttle and any given airliner, such as a Boeing 747. When in aircraft mode, the wings would be expanded for optimal lift, and the jet engines, located above the wing on either side (for protection upon reentry), would be used for takeoff and normal flight. The craft would continue to gain altitude on these engines until they are literally choked from a lack of oxygen. Once maximum altitude is reached, the wings are retracted and stowed in a streamline position. When the jet engines are cut, the main rocket engines are fired. These are located at the rear of the spacecraft, and would be not unlike the engines used by the current space shuttle. Working on the basic principle of combusting liquid hydrogen in the presence of oxygen, these engines would provide enough thrust so that the spacecraft could enter or escape the orbit of the Earth. These tanks would be as small as possible (to conserve weight) just to get the craft out of Earthıs orbit. If they were used later in the mission, perhaps for a boost to the moon, the shuttle would most likely need to be refueled. Once in orbit, the shuttle would perform almost exactly as our current shuttle does. A set of smaller engines, an Orbital Maneuvering System, would be used to make changes in the orbit, and a Reaction Control System would automatically keep the spacecraft stable, using small vernier thrusters. When ready to leave orbit, or reenter the atmosphere, the smaller OMS engines would be fired, slowing the velocity, and pulling the shuttle into a free fall. From this point on, the shuttle could glide into an airport as the current shuttle does, or it could extend it's wings and fly on jet engines to wherever it's destination might be. This is another great feature that makes my shuttle safer and easier to operate. The current shuttle must be on a precise schedule and glide directly to a specific runway. If my shuttle has a change of plans, or an error is made, it has the ability to "go around" or switch airports. In this shuttle, mistakes can be made without consequences, in the current shuttle, it doesn't work that way. One more aspect of this flight, which makes it so much easier, is that it is completely independent. Just like any other aircraft, this one must follow the instructions of an air traffic controller, but it also has the independence of being completely self contained. A GPS system would work with an onboard computer to make precise calculations on when and where to fire thrusters. That way, split-second decisions can be made, and entire flight plans can be altered without the aid of a ground crew. And the pilot does not have to be a rocket scientist either. By abolishing the need for a ground crew, flights are made more routinely and best of all, much cheaper.

The structure of my shuttle is also fairly similar to that of the current shuttle and other large aircraft constructed today. The frame of the shuttle would be composed of aluminum, to save weight, as in other aircraft. Now, the tiles that cover the current shuttle have proven to be very effective, but they are also extremely expensive to manufacture, and require massive amounts of time and effort to lay them or replace them. I was planning therefore, for the hull of my shuttle to be covered with sheets of metal instead, probably titanium and reinforced carbon-carbon, the highly heat resistant material used on the nosecone of the current shuttle. The protective ceramic coating could then be painted onto the hull, costing much less than cutting individual tiles unique to that specific shuttle. I couldnıt determine what the cost would be to cover the entire surface with titanium and reinforced carbon-carbon, but I'm assuming it would be very expensive. However, the time it would add to the life of the shuttle, and the reduced need of constant maintenance would prove to outweigh the initial cost of such metals. The cockpit and crew quarters of the shuttle would be constantly pressurized, while the cargo bay could be pressurized or depressurized depending on the requirements of the mission. The crew would even have the ability to pressurize and depressurize it in orbit as many times as necessary. This would be made possible by a series of vacuum pumps and storage tanks located at the front by the airlock. This is one other feature that makes this design so versatile; custom crafts could be requested by individuals, in which no cargo bay exists. The design could be slightly altered to make a shuttle that would hold as many passengers as any other jetliner, or the cargo bay could be expanded to lift larger payloads.  All other areas of the shuttle would not be pressurized during the mission to avoid possible hazards. During a standard mission, they would be flooded with cool, dry nitrogen gas in order to evacuate any hazardous gasses, including oxygen. This is a precaution taken by the current shuttle as well.  This would be done before takeoff, and as altitude is gained, the areas would slowly be depressurized to match the conditions outside the hull, and the nitrogen gas would be collected for later use in small thrusters, or the environmental systems. If an emergency happens to occur during a mission, all areas of the shuttle could be pressurized with oxygen so that a crewmember could fix the problem without the aid of a large, bulky space suit. This would greatly increase the efficiency of the crewmember, and it would make the job much less dangerous.

One thing that bothered me when researching the shuttle was of the sheer complexity of it all. There are so many separate systems and components that have to be checked constantly to insure the survival of the next crew. My family has several old vehicles that we use at our ranch, and if there's one thing I've learned, itıs that the less complexed, the more reliable it is. I tried to take this into account when designing this shuttle, and I was thinking of ways to make it as simple as possible, and therefore, more reliable. Unfortunately, I don't think there are many ways around it. If anything, my design is probably more complex than the current shuttle. But a lot of that complexity can be justified by the amount of redundant and backup systems involved. I think that the next shuttle built, even if not this design, should use as many generic, replaceable, and simple components as possible. This alone could make the shuttle safer, and easier to repair in an emergency.

Like the current shuttle, power requirements would be met by several hydrogen-oxygen fuel cells, which would in turn provide water for the crew.  The shuttle would also be equipped with enough battery power to survive several days in the event that the fuel cells fail. It would hold three independent cells, so, in addition to the batteries, a loss of power in this shuttle is very unlikely. All systems onboard the shuttle would be powered by direct current, contributing to the simplicity of the design. While in orbit or high altitudes, the fuel cells would directly power an electric hydraulic pump. The payload bay doors would be electric, as would be the robotic arm, so the hydraulic system would not be needed in space. However, all control surfaces, the mechanism that extends and folds the wings, as well as the landing gear would all rely on hydraulics. The two hydraulic pumps (one used only for backup) would be located beneath the payload bay next to the wings. Upon reentry, the fuel cells would initially power these pumps, but in mid-flight, the task would be assigned to the jet engines.  There is no risk involved here, as the generators on the engines would be tied into the same bus as the batteries and fuel cells, ensuring a smooth, uninterrupted transfer of power. The same would apply on takeoff. Until the jet engines are taken offline, they would supply all electrical power. On the ground, when an average jetliner would be powered by an auxiliary gas turbine, the shuttle would just use batteries.

The current shuttle uses an extraordinary amount of rocket fuel in a launch.  Just looking at the size of the fuel tank, compared to the sized of the shuttle will tell you that. The logical approach would be to somehow shorten the distance of the launch and used the lifting power of wings, instead of trying to lift 105+ tons of dead weight. That is exactly what my design does. Hopefully, this method would be so effective that all fuel needed could fit into internal tanks. If the airframe can simply not lift the amount of fuel needed, a mid-air fuel transfer could be required. This would be expensive, and would make a flight much more of a hassle than planned, but it would still be cheaper and require less manpower than the current launch procedure.

Of course, since the shuttle was built in the 70's, the original computers and controls were not very advanced. This is one thing that has constantly been updated throughout the years. The recent addition of the "glass cockpit" and integrated computer systems that help the astronauts control the flight have made the shuttle much more efficient. My shuttle would be designed to use the same basic computer systems as commercial aircraft, altered for space flight. That way, just like the shuttle, it could be upgraded as new advancements in hardware are made.

The current space shuttle works. It is by far, one of the most advanced vehicles ever built by mankind. There is nothing wrong with it, but we could make it so much better. All future goals could be accomplished with today's shuttle, but they could be achieved much easier if we just make the launch a little simpler.

Sources:

Space Shuttle Reference Manual

Boeing.com

dsc.discovery.com

World Book Encyclopedia

Last Updated: 09/07/01