What type(s) of space vehicles do we need?

[rlb2]

Zubrin proposed over 15 years ago to use the Space Shuttle returnable external solid rocket boosters and modify the Liquid external tank to accommodate other shuttle type missions minus the Space Shuttle; it also could be used to send men and payloads to Mars. I'm sure these ideas have been thoroughly discussed so I am not telling anybody anything new here. I also think some configuration of the space shuttles solid rocket booster should be used. There should be a better cheaper way to get to low earth orbit, a two stage to orbit would be the most cost effective way. Orion and the other competing design have there good and bad reasons why they should be built but the safety over the cost will end up winning out in the end, favor Orion. I also believe like so many others that in order to make space more available and commercially workable we will have to bring the cost way down. They tried to do this with the single stage to orbit X-33, 1 billion dollars and 10 years later they failed. I designed some unusual types of space planes that I fantasized may be of some importance some day years ago, below are a few of the ideas.

Above image shows a returning space capsule with retractable wings and landing assembly. The parachute slow the capsule to sub-sonic speed then the landing assembly and wings retract out after being lowered from the its detached top. For the price of one parachute (mass) while increasing the other two parachutes diameter to a larger size the wings and landing assembly mass would almost pay for themselves by using two landing choices - one by sea the other by a runway landing.

Above the Heli-Rocket takes off either horizontally with help from a booster fly-back rocket and a gravity assist or vertical as shown in above image on top of a Delta IV or Titan IV rocket.

The Heli-Rocket descends through the atmosphere with small winglets that helps provide guidance and stability, no large wings to add to the mass. It deploys its helicopter blades, after getting to an acceptable attitude and slowing down to sub-sonic speeds.

The helicopter blades help slow its speed down and provide lift to land the Heli-Rocket at any place on earth.

Gravity assist, 1/4 of the rocket fuel used on the space shuttle is expended getting up to 400 kilometers per hour the speed of a rocket launched sled using gravity assist to get up to speed, therefore a two stage to orbit spaceplane can be launched economically.

See these designs and more at: http://shineinnovations.com/index.html

 

[Prius]

We need a light cargo transport (for the ISS), a personnel shuttle (also for the ISS) and a heavier cargo transport (like the Ares V). I think it could be very cheap and efficient to have a modular ship design, with standardized docks and attachment points. Then we wouldn't need to develop an entirely different craft to send people to the moon; we could send up a resupply mission to the ISS with a few extra pieces, assemble those in orbit, and dock them with a propulsion section. If we decide we wanted to get to Mars, we could take a moon vehicle, strap on a bigger engine and some more supplies, and launch it and that would be it. If we come up with a better life support system, we don't have to replace the whole vehicle, we just swap out the LSS. We could save millions.

 

[Mindboggle]

When it comes to humans in space, we haven't even gotten started yet. It's like walking up to the edge of the swimming pool and sticking your toe in the water. That's where we are now.

What I feel would be the best type of space vehicle at this point is simple. International. Why should the people of earth have 10 different space programs all trying to do things independantly instead of pooling the resources and sharing the expenses for a common purpose. A little cooperation from the more advanced nations of the world would have nice spin off benefits for all. We finally put our collective heads together on the space station, why not continue the trend.

I like the concept of using low energy technology to get off the ground and high into the atmosphere and then launching into space. I don't know the physical limitations of what a helium balloon can lift but I think it's allot. I think we can get halfway to orbit or so without burning much fuel so it would take much less energy to get the rest of the way. I used to hear about using mag-lev tech to get a vehicle up to speed and propelling it up a long ramp as a primary boost into orbit. Whatever happened to that?

At any rate, we clearly need a safe and cheaper way to get payloads into orbit. I don't think it should be all about manned missions. We can cut so much cost by not taking people out there when we don't need to.
We do however need a manned vehicle for certain missions but it shouldn't need a huge cargo hold. Send the cargo up first and the manned ship can dock with it if need be. This adds versitility.
For extended manned missions, permanently orbiting mini stations could provide more comfortable living quarters for multiple missions over many years.
Also since we are cluttering up our orbit with dangerous trash we will soon need a way to clean it up. A robotic orbiting space dog should be designed to fetch the litter. They probably won't do anything about it until we lose a spacecraft full of people.
We should go back to the moon. Send in the robots to study the geology first but I believe we should have a permanent presence on the moon. Start mining what we can from there so everything doesn't have to come from earth. Almost everything could be done by robotics controlled from earth.

Basically, we need to stay at the edge of the pool a while longer. Humans are still not ready for advanced space travel but our machines could be. So concentrate on that for now. Also concentrate on this wonderful planet that we have. For now, Earth is out best spaceship. We need to take better care of it.

 

[Usarian]

What we *NEED* is ambition, vision, a sense of discovery, leadership, drive... a hunger for more.

..aaaaand money.

What we need is a reason to launch vehicles.

Monetary incentive.. *BIG* monetary incentive to launch vehicles.

I see it this way:

We need a multi-trillion dollar rotting space manufaturing and mining platform, nuclear powered, equipped with VASIMR rockets, built to a certain point in orbit, then flown to the asteroid belt and start mining. Initially material would be used to complete that station, but then it would become a refining station.

Tugs would be built equipped with VASIMR or the like to haul the material back to earth orbit where a smaller station would be built to serve as an orbital manufacturing platform.

Employees and tourists travelling to the mining station would be launched into orbit in a large module configured to be picked up by the tug.

One VASIMR configuration is able to make it to Mars in 30 days, so the Asteroid belt would be 60 or 90. Centrifugal "gravity" would be available upon arrival.

The endeavor would span about 50 years and cost about $1,000 trillion, BUT

THAT's what we NEED if we're ever going to get off this rock.

 

[gman42]

IMHO We really need just one spacecraft. What I mean is a true spacecraft that is a "space-only" spaceship designed to operate and travel in space for extended times. All of today's spaceships owe their design's and limitations from the launcher that puts them in space. The perfect analogy for a true spaceship is a sea going vessel that only operates at sea over a lifetime.

 

[svenlittkowski]

What type of space vehicles do we need?

Obviously, main problems we encounter are:
- high technical and fuel costs
- difficulties through high complexity
- extremely large one-way vehicles
- hazardous to the ecological environment

Space Vehicle

Therefore, we need to concept a type of space vehicles which should be re-usable many times, made of very cheap but resistant materials, and be sturdy and very simple but reliable in its technical make-up.

Launch Pad

The launch into space should not be via fuel-intensive rockets, but like the Romanian and Jamaican team (http://MoonRunningsJamaica.Jamaica-Focus.com) for the Google Lunar X Prize suggest, rely on a simple but very large hot-air balloon which can bring the vehicle around 10 to 15 km high in attitude.

A - Winged High-Altitude Space Carrier

Only from there a fuel-propelled continuation of the way into space is required. That could be done with a high-altitude space carrier (manned or unmanned) which is equipped with extremely large wings for the upper low-density parts of the atmosphere. That launch vehicle will be able to glide back to the ground, like the balloon launch pad, too.

B - Space Lift

Alternatively to the Winged High-Altitude Space Carrier (A), another option is thinkable: a space lift which reaches down from an orbital departure space station. Only on demand, thin but ultra-durable "ropes" are brought down from that special space station (an orbital terminus) to pick up the space vehicle from the balloon launch pad in an altitude of 10 to 15 kilometers.

Solar System Travelling

A ship capable of traveling within our solar system, would be very different. Forget landing and lifting up from planets. Such a ship would remain outside of atmospheres. However, it may be equipped with mechanisms to locate resources needed to refill the own propulsion demands, and also planetary landers to touch ground on planets or asteroids to harvest such resources. It will need facilities to convert raw materials to the resources required.

Such a ship, if manned, would need to produce food for the crew, and the necessary atmosphere. Food production would happen by avoiding to grow regular plants and animals, but by growing organic mass in a nutritional fluid. There will be different organic products: masses similar to regular meats, masses similar to mushrooms, and masses similar to fruits and vegetables. Already today it is possible to grow ear tissue in such nutritional fluids, for medical purposes. Those masses would have no brain and cannot feel pain, and they are all consumable - no bones or organs. Therefore this system maximizes the usable (eatable) part to nearly 100%. There will be other organic masses which will not grow in a block but on meshes, that will be the lung of the ship. used air is streamed permanently through that large and organically covered mesh area, and converted into fresh air. Another organic and mesh-alike mass could refresh and clean used water, like a huge green liver. All these organic masses are product of genetically extremely modified plants or cells.

There might be even an area like a park on board of such a ship, however, those plants serve only beautification and as occupation for the crew on their long voyages.

Artificial gravity, today still an unsolved challenge, will be necessary to keep our regular, unaltered bodies fully functional. Otherwise, there are thoughts to send genetically modified humans, having four arms instead of two arms and two legs, and such (legs are of no use in a low or zero gravity environment).

Propulsion: today's rocket engines are of no use, they waste too much fuel. A tomorrow's propulsion will be based on very different physical fundaments. To be honest, I don't have much idea what it could be, but whatever it is going to be, it will be fast. Extremely fast. Or, if not fast, then it will bend the dimensions and create a wormhole shortcut to its destination, maybe.

What would such a ship possible be made for? Maybe one or some of those purposes:
- transport of goods
- transport of living freight
- establishment of settlements
- scientific research
- resource harvesting

 

[tbscope]

I haven't read all the posts yet, so it might have been mentioned already.

In my opinion, the future of space travel isn't being made by NASA or similar organisations.
The future is being made by private companies, like http://www.reactionengines.co.uk/ and http://www.scaled.com/

The ESA is funding a project of reactionengines. And I think the NASA should do the same. In stead of building rockets themselves, they should invest in companies like scale composites etc...

 

[Lancelot_64]

For interplanetary travel we need bigger craft, it may be intelligent to build it in orbit such as the international space station was built. To Journey to mars I would expect a vessel at least as big as the international space station and steeped with redundancy (remember Apollo 13). Artificial gravity would be a requirement in my estimation. I'm abit extreme I guess - considering I have on the tip of my tongue "build them out of concrete or a product similar to concrete derived from the moons surface". Materials cost should be an easy puzzle to solve considering the moon is nearby.. It is only logical to build large craft from the moon until the space elevator or another cheap alternative is reality. Moon based manufacturing facilities - interesting. Use inflatables if necessary.

I applaude the gentleman who stated that we should leave the orions in space for future missions and use a specialized vehicle for re-entry...

As for the shuttle I would scrap it and go for a single stage to orbit craft, retaining the ability to land as a plane (but under power unlike the shuttle).

Does anyone know if the "Break through propulsion" project is bearing any fruit? Rockets blah..
My personal hopes is that they powers that be double down on revolutionary propulsion and ssto..

 

[joeCahh]

yo, we need spaceship that like do all kinds of things. if we had ships with transporters we wouldnt have to waste all that gas getting to space and back. and they should be big so you could have a room for a bar and maybe a pool table. also, we put some kind of weapons like phasers or lasers so if those grey biatches come back they can taste it. OH, and a cloaking device would be could so those chinamen cant shoot at us. i know it would cost more for this cool stuff, but i think it would be worth it. PEACE!

 

[jumlum]

Some people may not know that the X-33 was to replace the space shuttle. But, had problem with fuel tank design and cracks in the tank. But, no mather what space ship is built we are still using 1960 designs to do 1960 missions. What we need is a space ship that can reach light speed or close to it. We went to the moon 50 years ago and there is nothing new thats needed to go to the moon. But, the hubble telescope can see 13 billion light years into space and we can't travel a light second. Light speed is the only way that space travel can move forward. Going to mars will only prove that mars is like earth with no surface water and less gravity and colder which is already known. As of now a trip to Mars will take two years even if the stay was for one week. Light speed would open up a new era in space travel. Going to the moon or mars really don't advance mankind that much. Sorry! we need a new vision about space travel.

 

[JKarl]

While most of the discussion is on vehicles to get to earth orbit, the moon or planets, there should be a focus on potential orbiting facilities that could be used in space construction. A space dock and space port should be established in orbit to enable building small to large size space vehicles to perform various tasks, including cleanup of the space junk, continued maintenance on sattelites, testing of engines and fuel types, and educate a new wave of astronauts with real on hands flying experience. A space port will also enable a focal point for collection of space junk that can be potentially reusued or returned; a place to board vehicles to go to other locations like the space station, the moon or mars. The vehicles built in the space dock, should be "lego" type; enabling to add, change components dependent on the vehicle needed for the mission, so a recycle junk craft would have the necessary components to capture, retrieve and store junk. Other vehicles could be connected to carry multiple landing crafts, acting as a train or ferry to the moon to begin building a permanent base. The question would be, is it more economical to send 50 rockets fully fueled to reach the moon to set up a base, or send them up to an orbit, connecting the cargo and ferrying them to their final destination; reusing the ferry system for the trips.

 

[tbscope]

Jumlum,

But even lightspeed isn't fast enough to go to the nearest stars, let alone anywhere in our galaxy.
And beyond that, another galaxy.
I don't think we get there in the near future. And I don't believe creating a space vehicle that's able to fly with lightspeed is useful or economical. In my opinion it's better to start finding ways to go much further beyond lightspeed and skip finding ways to go near lightspeed.

 

[tbscope]

JKarl,

Check out http://www.reactionengines.co.uk/obs_1.html

 

[Danzi]

Why cant we fully re-usable space ships, e.g. Virgin Galactic space ship. Why do we have to use rockets that can largely NOT be used again. I mean, why cant we make ships such as the shuttles that be act like a ferry and go from Earth, stop and ISS then land on a runway built on the moon? I know to start with they would have to use Apollo type landers to do this and lay the runway, but why cant they eventually do that

I just dont get why NASA and most other space agency's use non-reusable shuttles! I know its a lot smaller but Virgin Galactic are the ones moving in the right direction!!

 

[gman42]

Why cant we fully re-usable space ships, e.g. Virgin Galactic space ship. Why do we have to use rockets that can largely NOT be used again. I mean, why cant we make ships such as the shuttles that be act like a ferry and go from Earth, stop and ISS then land on a runway built on the moon? I know to start with they would have to use Apollo type landers to do this and lay the runway, but why cant they eventually do that

I just dont get why NASA and most other space agency's use non-reusable shuttles! I know its a lot smaller but Virgin Galactic are the ones moving in the right direction!!

Virgin Galactic doesn't really have a spacecraft, it's more of a glorified aircraft with a rocket engine. It doesn't get anywhere to the speeds of a the Shuttle and will never get into orbit.

Technically the capabilities that Virgin has is 1960's NASA technology.

 

[mikecrane]

Here's my Idea.

It is an odd version of a launch track system. As many of us know the power requirements for a vertical electromagnetic rail launch system is currently beyond our technology. Some estimates require power 100 times greater than we can deliver with current public technology. My solution, compressed air.

Currently "keep in mind i did these equations on paper here" a launch vehicle uses about 25% of it's fuel reaching about 400mph. At a constant 5G acceleration that's roughly a distance of .375 miles. 1-G being around 32.17 feet per second accelerating. There for if a ship could be accelerated to about 400mph it would greatly reduce the overall weight and fuel requirement.

Today, there's really no way to do this and keep the ship man rated. Horizontal launch tracks are not practical due to the added distance a ship has to travel to reach orbit, or the energy lost altering the vector. Some have suggested a curved track or a track with one end elevated. The curved track adds to much g-force to be man rated, and a vertical or one end elevated track is just to gigantic or unstable to realistically get the job done practically.

What if there was an simple ultra low-tech way to get the job done? Why not launch from under the sea? If a tube with a massive spherical base were anchored to the sea bed it would create a much more stable launch platform. The tube could have a sled creating a near airtight seal much like an engine piston. The ship could sit atop the sled being accelerated by the sled.

While this idea isn't new, here's the simple part, how to push the sled. Use compressed air. The sphere at the of bottom the tube is filled with lightly compressed air upon start up. This air is compressed either by lowering the sled into place or by standard methods of air compression. Now in order to achieve the energy required for constant 5G acceleration the air must be compressed much further. This can be done by pumping sea water into the sphere which is at the base of the tube, the more sea water pumped in the greater the air pressure. The pressure at ocean depth will will greatly assist this process. Once the necessary air pressure is achieved, the sled can be released into a controlled acceleration.

Here are some numbers for constant 5G acceleration. At 1600 feet speed is approximately 435mph, at 5800' around 900mph, and at 2 miles around 1200mph. For those of us who like graphing (x^2+x)/2=32.17fps x=distance.

As seen in the calculations a shorter tube around 3/8 of a mile is the most efficient, greatest cost saving, and least technical. While a project such as this requires a massive amount of materials, it's not that complicated of a build. Easily achievable with current technology.

 

[krash]

Well, since we're fantasizing...

1) I'd like to see the Ares Program move forward.
2) I'd like to see the Space Shuttle evolve, improved and remain in service.

 

[Jazman1985]

There are several ways that we can reduce the cost of traveling to space. Cost will be the main reason for not continuing space exploration, mainly for mining, research and tourism reasons. For either of these to be reasonably affordable we need to reduce the cost of space access by one order of magnitude. Large launch rates of rockets are generally quoted as being able to do this, as reliability, time to launch, fuel costs, the cost of repairing reusable rocket stages and the cost of hiring personnel is reduced. I believe that we will, at least in the near future, need rockets to lift enormous payloads(20,000 kg), i.e. other spaceships, but not people.

I like mikecranes idea of using essentially a compressed air chamber to accelerate a payload. Launch a rocket through this system and you've added a good deal of delta-v that the rocket does not need to apply.(I realize the potential problems with launching a explosive rocket through a tight space such as a launch tube, but we can live with them.) These launch tubes are uneconomical(as far as design scale) for a payload direct to orbit approach though.

A Single Stage to Orbit(SSTO) approach is not feasible until we make massive gains in propulsion technology, even proposal like Reaction Engines Skylon, while appearing technically sound, have major drawbacks, essentially that they would not be operating anytime in the near future and will require massive amounts of money to research this new technology.

We've already heard in this thread that payload delivery systems like Pegasus can be air launched and deliver a 1,000 lb payload for a vehicle weight of 40,000 pounds using solid rocket fuel.(Haven't researched the specs myself but this sounds accurate) Spaceshipone and the X-15 have shown that is is feasible to launch a relatively large vehicle carrying people safely from an airbreathing platform. I believe that an airlaunch system is the perfect way to begin ferrying people into space for far cheaper. A design for a mothership of 1-2 million kgs is simply ridiculous though, why fly an entire airplane into the upper atmosphere when all you need is the engines? This is simply a waste of fuel and manpower, as another 2 pilots minimum would be required on this launch beast, add to this the cost of the ground crew to keep this 2nd vehicle running. In my idea, the main rocket/space plane will boast a simple tube body design and small set of wings, designed to operate most efficiently for reentry and landing(aka a reduced weight). The main rocket engine, utilizing LOX and RP-1 would be able to deliver manuevering capabilities and lift when exiting the atmosphere, negating the need for larger and heavier wings. The first stage of this design will be a second set of wings, airbreathing engines and fuel tanks attached, detaching at approximately 50,000 feet and after reaching approximately Mach 3.(Reducing overall delta-v by ~1.8 km/s) A simple parachute system could be utilized to recover the engines and extra lifting wing. Size of the spaceplane would be approximately 70 feet long, weighing 80-90 klbs with a payload size in excess of 4 klbs, large enough to launch 2-3 passengers. This spaceplane would reach no farther than LEO, needing something else, without the excess weight of a partially atmospheric vehicle to transfer the passengers.

Re-entry heating is not something that I'm knowledgeable about, but I imagine for a less dense structure is would be significantly less than the space shuttle. An airbreathing first stage has benefits such as reduction is fuel consumption, safer for passengers due to horizontal launch aborts and total reusability. New technologies could essentially serve as an add-on. Developed reliable high economy ramjets/scramjets since it was constructed? No need to remake the plane, simply remake the first stage and place more payload on the rocket.

As far as the Orion capsule, some are arguing that this appears to be a step backwards from "cool-looking" winged spaceplanes. We need to remember to use the most efficient vehicle for the job, and I don't think any spaceplane would be able to handle interplanetary travel better or more efficiently than a capsule. In the same regard, ferrying people to the ISS in a capsule might not be the best/most efficient idea.

my 2 cents...

 

[Miket1010]

I think Orion is a mistake and I agree with some of the other posters who said we should develop different vehicles for different uses. I have been pushing a modern version of Dynasoar launched on a Delta or Atlas to get crews into space and then develop a vehicle that just stays in space to carry crews and equipment between the Earth and the Moon and then have a seperate lander to go from lunar orbit to the Moon's surface.

Also, can someone explain why we can't use the 747 that transports the Space Shuttle from Edwards Airforce Base to Florida to fly a modified Space Shuttle to max altitude and release the shuttle to fly on to low Earth orbit? In the 1970's the Enterprise prototype was released from the 747 for test flights so inflight release can be done. Maybe even a liquid fueled rocket engine system could be used to boost the 747 carrier plane to a higher altitude before releasing the modified shuttle so it could fly on to orbit. Then you will have a completely reusable vehicle and no chance of damage from a shedding external fuel tank. The modified shuttle would have a smaller cargo bay due to having to carry it's fuel to reach orbit.

Obama wants to create jobs, open a assembly line for these new shuttles and orbital transfer vehicles. Then you will have high paying high tech jobs. Instead of 5 shuttles build several a year and then you will have maybe 20 or 30 vehicles so you could have a launch every week or two so crews could be sent to the space station or on to the Moon.

 

[docm]

Also, can someone explain why we can't use the 747 that transports the Space Shuttle from Edwards Airforce Base to Florida to fly a modified Space Shuttle to max altitude and release the shuttle to fly on to low Earth orbit?

The 747 transport can carry the shuttle but not it with a large enough fuel tank to make that burn. A made-for-the-purpose mothership, like but much larger than Virgin Galactic's White Knight 2, could do it with a smaller spaceplane, but only because its own weight is minimized while keeping a large payload capability. Trying to use a 747 means having to loft a lot of unnecessary structure.

 

[mikecrane]

Jazman1985


I too am a big fan of turbo fan launch platforms. I believe they will play a major roll in servicing LEO. I've actually seen a few ideas about cable towing to 50k' as well.

I thought about what you said with regards to launching from a tight space such as a launch tube. It doesn't necessarily have to be a tight space for the projectile "ship". The sled or piston is what has to fight tightly in the tube, the projectile merely sits on top. The sled basically acts as a reusable first stage capable of launching ships of several different sizes.

SpaceX has what i consider an excellent idea for the falcon launches, which is a launch hold. Where the engines are fired up before the ship is released. If a ship were to be launched from a launch tube, it be held in place running before the sled is even released, followed by a 4 second 5G sled ride to 400mph before it is released. The fuel for the hold doesn't even have to be on board, it can be pumped in from a tank which remains on the sled at separation.

 

[zenmaster43]

Earth to LEO:
Re-usable surface to LEO craft:
Phase 1: (Catapult low-angle launch to reduce fuel requirements.)
Phase 2: (Fly to high altitude and supersonic speed using turbojets and retractable wings.)
Phase 3: (Boost speed using scramjets, retracting wings as needed to reduce drag.)
Phase 4: (Orbit injection using kerosene booster rocket, same fuel as turbojets?)
Phase 5: (Orbital navigation using retro rockets)
Phase 6: (De-orbit by rocket braking)
Phase 7: (Reduce reentry speed by rocket braking)
Phase 8: (Kick on scramjets when air flow allows, then use vectored thrust to further reduce speed)
Phase 9: (Gradually extend wings and airbrakes to further increase drag, help slow to turbojet speeds and allow normal aircraft functionality.)
Phase 10: (Turbojet low-atmosphere navigation and horizontal or vectored thrust vertical landing)

If scramjets can use kerosene, the full sequence will work off of one set of fuel tanks.
Internal ducting and conical iris valves enable both turbojet and scramjet to share the same intake and exhaust ducts and thrust vectoring aparatus.
Rocket nozzle drag is eliminated for lift-off until just before scramjet-to-rocket transition by a conic iris shield.
Consider whether the scramjets can operate as rockets in space by injecting LOX and fuel into it's combustion chamber.
If so, this reduces the design complexity and lightens the craft, but is it as powerful as a dedicated rocket engine?
For the most part, we're talking off-the-shelf items here. Being able to swap out engine parts and avionics for standard off-the-shelf items should reduce costs tremendously, and gradually enable mass-production cost-scale benefits. Of course, all of it has to survive the rigors of the space environment and reentry, so some of these items may need to be reworked with different materials and some minor design modifications.

 

[mikecrane]

http://www.youtube.com/watch?v=bPVly2pXJcs

 

[quatermass]

Simple answer - Skylon.

http://www.reactionengines.co.uk/skylon_overview.html

 

[zenmaster43]

If the pneumatic launch tube concept were practical at all, it should be used in the most effective way possible, by boring a shaft deep into a very high mountain, as far down as possible, to maximize acceleration time, achieving a higher exit velocity, at a much higher elevation, where the atmosphere is much thinner and the resulting drag much less. Adding regulated combustion far below the craft, where only the exhaust's pressure reaches the aft of the craft can also increase the acceleration and might even result in a supersonic launch. This brings potential challenges in maintaining stability through the transition from zero drag in the the somewhat laminar flow exiting the tube at the same velocity as the craft into the significant drag of the turbulent surrounding air flow. If this can be overcome, then perhaps, just perhaps, it could be worth the effort.