... for example imagine that such guyed 2.8km high space tube in such special Triple mountain canyon could be build and it could replace 2 solid rocket boosters from Ariane 5 rocket...
Personaly, I always like Burt's 8 GE90-115 engine sled that would release a 400 ton payload at 50,000'.
Quote from: Nomadd on 05/02/2011 11:36 am Personaly, I always like Burt's 8 GE90-115 engine sled that would release a 400 ton payload at 50,000'.Now that I'd like to see... Do you have any source for that? Google turns up dry...
Quote from: Epis on 05/02/2011 04:03 pm I try to say that such launch assist system could be worth to explore deeper by higher number of experts, instead of saying that's too expensive, it won't work, but how do you know that ? there are no such design analysis if it exist put link to paper I will happy read and will drop that Idea.Its non viability is the reason "experts" aren't looking at it.It is not our job to show it doesn't work, the onus is on you to prove that it does work.Working around launch systems is a reason that one might know that this wouldn't work
I try to say that such launch assist system could be worth to explore deeper by higher number of experts, instead of saying that's too expensive, it won't work, but how do you know that ? there are no such design analysis if it exist put link to paper I will happy read and will drop that Idea.
Experts have been looking at it, from Eugene Sanger with the silbervogel in the late 30's over Philip bono with Hyperion in the 60's and Maglifter in the 90's to eLaunch Hypersonics the last years at Nasa. Not to mention some design studies arround ARTS and Hopper in FESTIP.The thing is governments don't have the guts to follow some out of the box thinking.From some official simulations that I was fortunate to look into I've seen that at datapoints below 6km altitude, current launch vehicles do not or hardly even reach supersonic speeds and have already burned about 25 percent of their fuel. This due to the fact that more than half of their generated Delta-V goes into losses rather than flightpath speed.So although its tempting to think about some more extreme concepts, even fairly low performance launch assists can decrease the dimensions of launch vehicles significantly or alternatively increase their payloads.In addition I think that rocket sled propulsion would work better for this porpuse than for instance maglev propulsion or a mechanical catapult working with dyneema cables and pulleys (although I was really amazed by some napkin calculations, might be a real possibility when thinking about lunar mass drivers (free breaking length effectively multiplies with a factor of 6 due to low gravity, but that is another discussion)The problem also might be that previous studies mentioned were only done by 'rocket scientists' and not in cooperation of civil engineers, at least the major attention mostly goes to the launch vehicles that are designed to utilise the launch assist.
http://moonandback.com/2011/04/08/jesse-powell-in-a-t-minus-5-on-ultra-low-cost-launches/http://www.startram.com/$20B to start, good luck with that.
Yeah I knew about that one. I also think this one is far out there. But even though on the surface it might look that the performance benefits are minor compared to constraint and cost disadvantages. But, there is always a but, if this relatively small performance upgrade tears open the realm of reusable single stage to orbit systems then it is worth a shot.
IF I was Usa president obama knowing this 1 stage rocket energy efficiency
you cant ignore Laws of physics, and laws of nature that says that in the end most energy efficient way of doing things will survive fare competition in market.
Quote from: fatjohn1408 on 05/04/2011 09:15 amYeah I knew about that one. I also think this one is far out there. But even though on the surface it might look that the performance benefits are minor compared to constraint and cost disadvantages. But, there is always a but, if this relatively small performance upgrade tears open the realm of reusable single stage to orbit systems then it is worth a shot. No, there is no "buts". The constraints make it unusable.
1. Unusable? Its not like you only have one specific orbit that you can target. The majority of delta-V should still be provided by the launch vehicle which can be done in any direction one wants. 2.With the use of lifting surfaces the orbit inclination can even be shifted significantly without serious losses (providing a good L/D) after leaving the rail.Granted that the advantage of a rail parallel to the equator won't provide much advantage for missions to polar orbits.3. But that is not where most payloads go. Unusable? I don't think so.
1. The turn to the proper azimuth will incur losses2. enough to negate the savings3. most payloads don't go to equatorial either, hence "unusable" because it doesn't provide savings since other sites are required.
1. For a large range of azimuths it won't be enough losses to negate savings 2. Not true for all azimuths, gains are provided of lift effectively transfering the vehicles momentum in the right direction. The losses are drag. Drag is easily smaller then lift.3. If that is true, why does everyone bother with launching from the equator? Launching with an assist is just like launching with a higher earth rotational velocity, which is widely believed to be an advantage for the majority of launches, except the few to polar orbits.
Also, nobody launches from the equator, not even ESA.
Quote from: Jim on 05/04/2011 03:05 pmAlso, nobody launches from the equator, not even ESA.Not trying to defend this launch assist theory but commercial launch services are placing payloads to orbit from the equator.http://forum.nasaspaceflight.com/index.php?topic=8862.msg723894#new