Arial refueling for rockets ?

[Vortexx]

PAST

The first actual transfer of fuel from one aircraft to another was little more than a stunt. On November 12, 1921, wingwalker Wesley May climbed from a Lincoln Standard to a Curtiss JN-4 airplane with a can of fuel strapped to his back. When he reached the JN-4, he poured the fuel into its gas tank. Needless to say, this was not the most practical way of refueling an airplane in flight.


PRESENT

Ever since, in flight fueling has been improved to become a semi-automated process wich can be done at high speeds, transferring large amounts of fuel.




FUTURE ?

So, if planes can be refueled, why not use a very long hose suspended from a stratospheric blimp to pump the first stage of a rocket during launch , extending it's range with a lower startingweight?

The hose i think of should be like 30 km's long and be reeled in by the blimp as the rocket goes upwards as not let the weight of the hose influence the performance/trajectory of the rocket.

Maybe the hose could be even used to support several kilometres above the refuel blimp (hose should be unreeled again) , before the weight of the hose defeats its purpose.

As the rocket finally detaches itself, firing it's second stage, the first stage is captured by / and dangling from the refuel hose and can be reused, no need for parachute system to recover the first stage.

[hypewaders]

Beamed energy will be a much more practical "hose".

[guthrie]

When i consider that tehy can barely manage to hit another incomign rocket on a highly funded high tech star wars program, what makes you think they could match orbits, velocity etc for long enough to transfer fuel? Remember the refuelling vehicle will have to be travelling at the same speed as the rocket.

[EI_Sparks]

You're going to reel in two hoses (fuel and oxidiser) to a blimp at a linear speed of ~3-4000 m/s??? That reel is going to have some interesting bearings....
Not to mention the motor - 30 kilometres of two hoses weighing, what, 6.75 lb per 50 feet (based on firefighting hose and ignoring the cryogenics that you'd need for real fuel and oxidiser - and these are for 1.5 inch diameter hoses, a bit small for the purpose) - that means the motor has to haul 12,000 kilogrammes upwards at up to 3,000 to 4,000 metres per second inside of say, five minutes (it's about nine minutes for the shuttle to get to orbit if memory serves) - that's about 22 kilotons of TNT's worth of energy in the space of five minutes. (Hiroshima was 13 kTons...)

[Undecided]

Why not develop that airborne launcher concept? The L-1011's carry a load underneath, and half the ride is already done for you. I know it's already in service, and the An-225 would serve as a perfect launch platform.

[RonVolk]

Undecided: Why not develop that airborne launcher concept?
I too wonder about this. The Antonov An-225 is the biggest plane on earth. First time I saw a picture of it I thought it looked like a C-5 but I googled it and its got more than twice the payload. (250,000kg - 275, 000kg? to the C-5's 122,472kg) With twice the payload the Antonov could lift more but if NASA puts some research into this concept it could probably use a few of the 50 plus US military C-5's and develop a lighter 2nd stage vehicle. The only problem I expect (besides NASA's usual bull) is trying to make the second stage effiecient, it'd still have to carry enough fuel to hit orbit and a decent sized payload.
I know it might be contrary to the current American way of doing things but I think more smaller, cheaper, launches is better than a few massive launches. Besides I've been in and around C-5's before, I don't think the US Military has released the full capabilities of them to the website I googled.


The L-1011 is in use already, doing it the smart way like you said http://www.orbital.com/

[Gifted]

You're right about the C-5. The military doesn't release everything to the public straight. There are reasons for that. Anyway, yes, most payloads, including humans, don't need a big huge launch vehicle. There are only a few loads that need large capacity on one launch, and eventually, as we procure resources and start building those in orbit, they will no longer be needed.

[Vortexx]

Sparks, you are right, the bearings would be too interesting

But I feel it is important we keep examining ways of detaching the fuel from the cargo, because that is what keeps chemical rockets so expensive.

The airlaunch concept is very promising, you wouldn't even need an Antanov for large loads if you use multiple launches and assemble the parts/stages in orbit??

[RonVolk]

Just a few thoughts on the matter.
Yea I know the military doesn't release everything to the public (I was in the Military very recently and they didn't release everything to us) I bet NASA could get a hold of some military hardware if it asked.
Assembling things in orbit would probably be best if done entirely by computer guidence systems, however I'm not 100% positive current computers could do it.
I think the second stage craft would be two completely different craft, one for carrying passengers that can survive reentry and a cargo craft that would be destroyed if it fails to reach orbit. Losing cargo would be bad but definatley more acceptable then losing human life and probably cheaper then trying to build two different infaliable craft orsomething like the space shuttle.
So I figure something like this would work. First step start launching Spaceship sections in orbit second step as they get near each other a computer on each individual part is going to have to guide the parts together and connect them, or a computer sattelite located near the parts to give them quick orders for connecting and course changes, third step is send people up to check out the assembled spacecraft run system checks then take off to wherever. Did I miss anything? Maybe I should start a new thread for this idea but I think its a pretty common idea probably has been discussed before.

[ElectricFetus]

beam energy:
http://www.islandone.org/APC/Beamed/06.html

[RonVolk]

WellCookedFetus about your beam energy. The site you gave said, "For comparison, a typical Earth-launch vehicle (of any kind) requires "jet" powers on the order of 0.1 MW per kilogram of vehicle" Maybe I misinterpreted it but that suggests we'll need .1 megawatt per kilogram of vehicle, Meaning 10 megawatt energy supply could launch 100kg's (220lbs)
According to http://www.usbr.gov/lc/hooverdam/His...powerplant.htm
Rated output of hoover damn powerplant is 2074 megawatts so the Hoover dam at rated output could lift 20740kg or 45628lbs (damn thats alot)
Acording to
http://www.islam-online.net/english/...rticle04.shtml
The Millstone Units 2 and 3 nuclear power plants in Connecticut have an installed capacity of over 1,900 megawatts of power on a 500-acre site designed for three nuclear plants, so if I estimate each plant at about 950mw each and a third is built that means 2850mw for a total lift of 28500kg or 62700lbs
The idea has merit but there's alot more laser research that needs to be done and alot of infrastructure that needs to be built if it were to become a reality. I think there's also a higher risk with the plan vs other plans. call me crazy but a MW laser, a craft trying to get in orbit and a massive amount of energy being produced all in close proximity to one another just sounds too risky. If NASA backed this Idea 100% towmarrow It would probably still take them 15 years to make anything happen while the airborne launcher has already worked (http://www.orbital.com/SpaceLaunch/) and could be made to work much sooner.

[ElectricFetus]

Nope that is absolutely right! We would need a 40Gw laser array to launch a space shuttle size laser plane, say 20 2Gw nuclear power plants!!! Even though it is much more technologically feasible at this time then a sky tower!

[RonVolk]

Definatley, More feasible than a sky tower but less then an airborne launcher. Considering the rate technology has advanced over the last 100 years we'll probably have either a cheaper power source in the next 25 years or a better way of getting in orbit. Anti-Gravity if you want to think Sci-Fiction like this guy. (http://www.smh.com.au/articles/2003/...534050248.html)

[ElectricFetus]

Please don't hit us with such circumstantial and unproven hypothesis on anti-gravity! You want this thread move to psuedoscinece?

I’ll believe it when I see proof and as of so far no functioning means of such propulsion has even been verified.

[RonVolk]

Yea, I thought giving you that site was kind of stupid after I posted, I was trying to illustrate that the future is unpredictable and if we dump a massive amount of resources in one direction we might be wasting our resources cause of the rate technology is developing.
I ran across this on a related search.
http://news.spamcop.net/pipermail/sp...ay/006866.html
"During off peak hours the rates are cheaper, so the power is used to "fill" the upper lake. During peak usage the water is allowed to flow back to the
lower reservoir, producing cheap hydro power."
Seems to suggest that the total megawatts produced by the power plant wouldn't have to be that high in fact if you only planned to launch every couple of weeks and had a near unlimited source of water a big powerplant and a bunch of massive hydro-electric turbines. Normally I go for the KISS aproach but that isn't always an option. I thought there was an energy launch thread but I don't see it maybe we should start one?

[ElectricFetus]

And do you know how big the capacitors would be to store enough power for a 40Gw laser array to power say 20 minutes at full thrust??? Though now that I think about it a capacitor array the size of a oil tanker power by one nuclear power plant does sound much cheaper then 20 nuclear power plants. Good idea

[RonVolk]

I don't know enough about electronics to know if capacitors would function well if they were that big or alot of them. I did find these two sites about capacitors very enlightening. http://hop.concord.org/amu/amu.concepts.caps.html
http://www.rpi.edu/dept/phys/Dept2/p...res/Demo03.doc
I couldn't find anything about massive capacitor arrays. Building an enormous holding tank might be cheaper cause its working off technologies that have already been developed and relatively cheap materials however, a holding tank big enough for this would probably require an effort nearly equel to building the panama canal.
If you know of any sites about building massive capacitors please post them. I don't know if you've mentally beat this idea to death yet or not but its starting to get interesting to me.

[EI_Sparks]

Sorry RonVolk, capacitors are used in many laser applications because they release all their energy in the shortest time possible, not because they can dump lots of energy out over a long time (like 20 minutes).
You'd have to have a conventional energy source like a powerplant to sustain that power draw for that length of time.

And frankly, I'd hate to see the effects of a 20GW laser beam from anywhere that could be considered close. Ionisation of the local atmosphere leading to lighning strikes and other local meterological anomolies, radiated heat from the air molecules and water vapour in the beam, and you really wouldn't want any flocks of birds in the area...

[RonVolk]

hehe yea, flocks of "well" done bird(s). I Didn't think about the atmospheric effects except for humidity reflecting light away from the target causing a slight decrease in the lasers strength. Heated air would probably create wicked updrafts and downdrafts that would last after the laser was turned off. Oh well, time to come up with a new plan.

[EI_Sparks]

hehe yea, flocks of "well" done bird(s).

Er, no - that much energy would heat up the air around the beam tremendously, so if they didn't turn away fast enough, they'd be cooked and burnt crisp before they even reached the beam itself. Were they caught in the beam itself, they'd vapourise if they didn't actually become plasma...
So there'd be nothing left to even recognise.

Oh well, time to come up with a new plan.

How about waiting a few years and buying one from the Japanese?
http://www.hobbyspace.com/AAdmin/arc...s/Inatani.html