|
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Alternative fuel systems for aero-space
all the space vehicles today depend on combustion tech for launching
purposes . this technology which depends on an oxidiser and a fuel gives just enough thrust to take a space vehicle from the earth surface to the space against the gravity. now the speed and fuel capacityof these vehicles will not be enough for long space missions ....so is there a way by which we can use an alternate technology to launch space vehicles without using combustion technology ...is there a way to over come or anull the gravitational forces and make a body levitate ....? |
#2
|
|||
|
|||
kausikram k sayee wrote:
all the space vehicles today depend on combustion tech for launching purposes . this technology which depends on an oxidiser and a fuel gives just enough thrust to take a space vehicle from the earth surface to the space against the gravity. now the speed and fuel capacityof these vehicles will not be enough for long space missions ....so is there a way by which we can use an alternate technology to launch space vehicles without using combustion technology ...is there a way to over come or anull the gravitational forces and make a body levitate ....? That's an interesting question. There has been some talk about using carbon nanotubes (CNTs) to create a space elevator, but unless the cost of production for CNTs decreases a great deal, this will not be a feasable option. I believe CNTs costs are on the order of $1000/kg. If you are concerned with fuel depletion over a long duration, electric propulsion (EP) is the way to go as it makes efficent use of propellant. Though it is not very powerful, EP powering a spacecraft would be an ideal choice for exploration missions or missions to the outer solar system (Deep Space 1 and JIMO, for example). EP only operates in a vacuum environment, so it will require a two-stage launch, most likely the combustion engine you mention. -Victor |
#3
|
|||
|
|||
Victor wrote:
That's an interesting question. There has been some talk about using carbon nanotubes (CNTs) to create a space elevator, but unless the cost of production for CNTs decreases a great deal, this will not be a feasable option. I believe CNTs costs are on the order of $1000/kg. last time I look for this was 100$/g probably now they are around to 50$/g. $1000/kg would be a very good (for now) price tag for industries and enought to start build the SE. Mirco |
#4
|
|||
|
|||
|
#5
|
|||
|
|||
quasarstrider wrote:
(Bill Kno) wrote in message om... CNTs will become less expensive to make. The space elevator will become the "cheap" way to get, not only into space, but also as far as Mars and the astroid belt. Assuming they can make them strong enough that is. I do not believe strength will be an issue. I cannot recall exact number off the top of my head, but Wikipedia puts the strongest CNT specimen around 63 GPa tensile stength, (http://en.wikipedia.org/wiki/Carbon_nanotube). With advances in the field of CNT alignment and growth methods, I believe 63 GPa will soon become the norm, only to be surpassed by stronger "recipes" of CNTs. As for the cost of CNTs, I agree they will become cheaper manufacture. Right now, I believe it is a question of material science engineering and growth methods. Once a cheap, reliable method is discovered, the "CNT door" will open into many other realms, not just the space elevator. |
#7
|
|||
|
|||
(David Summers) wrote in
om: (quasarstrider) wrote in message . com... (Bill Kno) wrote in message om... CNTs will become less expensive to make. The space elevator will become the "cheap" way to get, not only into space, but also as far as Mars and the astroid belt. Assuming they can make them strong enough that is. Actually, I believe the final limit on Space Elevators will be maintainence. Repair and upkeep on an object 50,000 km long in a hostile environment (with asteriods coming in at 20 km per second) will end up being more expensive then launching a high-tech rocket. The other problem I see with an elevator is throughput. Realistic elevator technology will make the time to orbit about a week, while a rocket gets there much faster. It may be more reasonable for bulk cargo, like modern trains, but it probably will not be as cheap as other methods (using the same materials) because of the maintenence problem. You're not kidding hostile environment. The elevator has to be on the equator and go all the way up. Since the orbit of EVERY satellite MUST cross the equator, any satellite below geosynchronous orbit will be a potential collision hazard...and at great speed to...in LEO its like 7km/s. Plus its not like you're just going to be able to move this flimsy cable out of the way, unless you put thrusters in the middle or something. Tom |
#8
|
|||
|
|||
Plus its not like you're just going to be able to move this flimsy cable
out of the way, unless you put thrusters in the middle or something. Well, at http://www.isr.us/Downloads/niac_pdf...0.html#objects they propose moving the space elevator by moving the anchor point (which they have on a Sea Launch style floating platform, largely so that they can move it). In fact, that site (in particular http://www.isr.us/Downloads/niac_pdf/contents.html and in general http://www.isr.us/SEHome.asp?m=1 ) makes a pretty good stab at answering the obvious objections to space elevators. They answer the usual questions of the form "oh but it will never work because of X" for a variety of values of X. |
#9
|
|||
|
|||
Jim Kingdon wrote in message ...
Plus its not like you're just going to be able to move this flimsy cable out of the way, unless you put thrusters in the middle or something. Well, at http://www.isr.us/Downloads/niac_pdf...0.html#objects they propose moving the space elevator by moving the anchor point (which they have on a Sea Launch style floating platform, largely so that they can move it). In fact, that site (in particular http://www.isr.us/Downloads/niac_pdf/contents.html and in general http://www.isr.us/SEHome.asp?m=1 ) makes a pretty good stab at answering the obvious objections to space elevators. They answer the usual questions of the form "oh but it will never work because of X" for a variety of values of X. What I was referring to was not a killer impact, which has been addressed as you say. I was talking about the buildup of non-lethal impacts. For example from the data on the site you gave, a one micron object will strike the cable in a given section length 200 times per day (the linked article was unclear about the length in question, but the width is 10 cm). Each of those collisions very slightly, almost unmeasurably, decrease the strength of the cable. My point is merely that this means constant maintenence will be required to replace worn cables, on a very large object. From a business point of veiw, this makes owning a cable a very expensive proposition. Not impossible to do mind you, just expensive. I believe that the same advances that the cable requires, when applied to an RLV will be more cost effective (smaller object, less maintenence). (Basically, we are finally getting our pre-orders of unobtainium!) -David |
#10
|
|||
|
|||
Can Microwaves be used to heat the air around it or something else? To
use a field effect and no longer need to use old style combustion? Mike kausikram k sayee wrote: all the space vehicles today depend on combustion tech for launching purposes . this technology which depends on an oxidiser and a fuel gives just enough thrust to take a space vehicle from the earth surface to the space against the gravity. now the speed and fuel capacityof these vehicles will not be enough for long space missions ....so is there a way by which we can use an alternate technology to launch space vehicles without using combustion technology ...is there a way to over come or anull the gravitational forces and make a body levitate ....? |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Unofficial Space Shuttle Launch Guide | Steven S. Pietrobon | Space Shuttle | 0 | August 5th 04 01:36 AM |
National Space Policy: NSDD-42 (issued on July 4th, 1982) | Stuf4 | Policy | 145 | July 28th 04 07:30 AM |
Clueless pundits (was High-flight rate Medium vs. New Heavy lift launchers) | Rand Simberg | Space Science Misc | 18 | February 14th 04 03:28 AM |
First Moonwalk? A Russian Perspective | Jason Donahue | Amateur Astronomy | 3 | February 1st 04 03:33 AM |
U.S. Space Weather Service in Deep Trouble | Al Jackson | Policy | 1 | September 25th 03 08:21 PM |