Author Topic: Aerial Propellant Transfer re-usable launch system  (Read 49755 times)

Offline Andrew_W

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #20 on: 06/30/2011 10:27 am »
Another possibility mentioned in the original Black Horse proposal was buddy-buddy refueling between two orbiters, both in a sub-orbital trajectory to increase the payload to orbit or the orbital altitude of one of them.
« Last Edit: 06/30/2011 07:12 pm by Andrew_W »
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Offline Jim

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #21 on: 06/30/2011 12:16 pm »

The shuttle already transfers cryogenic propellant inflight between the ET and orbiter, Falcon Heavy will be transferring LOX inflight with its cross feed system, it's only the actual coupling inflight of cryogenic systems that hasn't already happened.


A shuttle and FH are non-applicable analogies. Inflight refueling will require coupling and uncoupling, extensions, and retractions and rotations.

Offline Epis

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #22 on: 06/30/2011 04:50 pm »
I think all plane launch assist concepts are going in wrong direction, what we need to do is to look at those plane technology that offer largest payload combined with high speed, and if we look at wiki besides conventional planes there are alternative options like Ground Effect Vehicles http://en.wikipedia.org/wiki/Ground_effect_vehicle
there is interesting sentence
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The Lun ekranoplan had a potential lifting power of 1,000 tonnes
If I understand correct that these machines has higher cargo lifting potential than conventional airplanes, and digging deeper I found interesting concept planes that has cargo >1000 tons like Beriev Be-2500 Neptun and Boeing Pelican ULTRA (cargo 1400 tons, that would be enough to lift all Falcon Heavy 1400 Ton rocket fueled with 50T payload )
http://en.wikipedia.org/wiki/Beriev_Be-2500
http://en.wikipedia.org/wiki/Boeing_Pelican
and these concept planes are supposed to fly much higher than few meters above ground, like 10Km for Beriev craft and 6.1km for boeing at ~~800km/h.

so where is the catch here, why such super heavy craft concepts are ground effect ?
I think that these crafts has relatively short wing area and wings are closer to craft and of course stronger, so they need much larger liftoff speed, so imagine how long could be runway to take off such slowly accelerating giants it they ware conventional style ? and here as savior comes ground effect that lifts craft at much lower speeds and I understand that after ground separation craft can steadily increase its speed to 450 km/h which is optimal ground effect speed and after that craft can fly higher and don't need to use ground effect anymore to stay in the air.
one more problem that is resolved with water ground effect liftoff is landing gear, and it has some limits specially rubber wheels has limiting speed and size, so it would be really hard to engineer 2500 ton heavy plane high speed landing gear and that would weight allot.

So Idea is specially designed turboJet mach 2 capable  ekranoplan for  falcon heavy rocket 1400 mt launch assist that will take rocket to 20+KM altitude and will make vertical maneuver (with help of Falcon heavy rocket engines till altitude 35-40km, near 0 atmosphere pressure then separate rocket like space shuttle opens cargo door for payload release, this style payload release wound be simple and safer than doing it in low atmosphere where large air resistance loads could do unexpected damage  in separation stage.
advantage of this tech is scalability, it could scale to even larger sizes.
+ it doesn't need expensive runways.
+ can serve as cargo transport plane, when not in use

Offline Andrew_W

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #23 on: 06/30/2011 07:11 pm »
Epis.
There is nothing new in the idea of fully reusable TSTO the first shuttle concepts were exactly that, the only reason the shuttle wasn't done that way is cost. Developing an aircraft that can carry a cargo of hundreds of tonnes to high altitude at high speed costs tens of billions of dollars, the only reason I suggest that it can be done now is that most of the development has now been done, and it's been paid for by someone else.

Jim.
I don't think I'd need to look too hard to find examples of cryogenic systems that have extensions, retractions and rotations. How do they fuel the Shuttle on the pad? How do the motors gimbal? Are you suggesting that doing these mechanical operations as part of inflight refueling is going to be a show stopper?
« Last Edit: 06/30/2011 07:14 pm by Andrew_W »
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Offline RanulfC

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #24 on: 06/30/2011 08:28 pm »
I could find nothing on the web about The T-Space 3STO, there was a depiction of a dinky little two stage rocket attached to the belly of a 747 on the T-Space Wiki page, hopefully that's not what you're referring to.
Probably because the paper itself is now under the "AirLaunch" label:
http://www.airlaunchllc.com/AIAA-2008-7835-176.pdf

And
http://jcots.state.va.us/2007%20content/materials/tspace_advisorypanel.pdf

And the T-Space original TSTO wasn't "dinky" as it was almost 14 feet wide and a little over 90-feet long :)

The new 3STO vehicle is less than 10 feet wide, but still around 90 or so feet long with the same payload capacity. Given some possible "upgrades" such as pump-fed instead of pressure-fed engines and maybe an upgrade to Liquid Methane instead of Cyrogenic Liquid Propane would be able to boost that payload capability.
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Yeah, you're no doubt right about that, I think a traditional delta wing is far more practical.
Probably but then the Orbiter wing has to be sized to be able to fly with a full fuel load at the suggested altitude.
 
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The proof is in the results, inflight refueling is conducted by most Western airforces and accidents involving loss of aircraft are extremely rare, it's arguably safer than normal runway landings, certainly safer than carrier landings, which are routine operations.
Yes it's considered "pretty-safe" as a standard "military" operation, then again we play with explosives, dangerous chemicals, and nuclear weapons :)

Point of fact though it is NOT "considered-safer-than-a-normal-runway-landing" by either the military OR commercial aviation. It is in fact 'classfied' as a "high-risk-operation" and its use in "civil" operations would qualify as a high-insurance risk.
(I'm pointing out simple issues here not arguing which is better or worse by the way, "Air-Launch" is considered a "high-risk" operation for insurance, though the "aft-crossing" drop method of T-Space/AirLaunch is considered LESS risky)

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The shuttle already transfers cryogenic propellant inflight between the ET and orbiter, Falcon Heavy will be transferring LOX inflight with its cross feed system, it's only the actual coupling inflight of cryogenic systems that hasn't already happened.

Uhm, no those are not the same thing at all. Those operations will take place "inside" a single vehicle not having a flexible (required), extendable, (required), manueverable, (required) boom transfering thousands of gallons (and tons of mass) cryogenic fluids between tanks in one aircraft to tanks in the Orbiter. There were a LOT of issues found with the idea of transfering Hydrogen Peroxide and THAT is a "room-temperature" propellant. Cryogenics mean that the tanker aircraft has to have a LOT more insulation than a normal tanker does. It has to have specialized venting systems depending on what is being transfered (Liquid Hydrogen is both worse and better than Liquid Oxygen but NEITHER has been studied much with the idea of air-to-air transfer) cryogenic compatible lines, links, and parts that can still move, bang against each other, and flex while at cryogenic temperatures. This is neither "easy" or going to be "cheap" to achieve.

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Rocket powered take-offs have been going on for about 70 years, there is no space launch system operating that doesn't involve rocket take-off, this is just getting silly.
NO it's NOT at ALL "silly" these are facts your are going to have to address! "Rocket-powered" take offs HAVE been going on for 70 years but it has only been RECENTLY that they have been happening anywhere but at a SPECIFIED SPECIALLY CONSTRUCTED AND HIGHLY REGULATED LAUNCH COMPLEX!

This is a MAJOR point to consider since if you are launching both your tanker and your Orbiter FROM an 'official' launch-complex/launch-range then you have to consider the "costs" of doing so versus say launching out of a "normal" airport. (The "launch-complex/range" will automatically add about a million dollars PER launch in fees from the start)

And I will repeat: ANY VEHICLE WITH A ROCKET ENGINE IS NOW CONSIDERED A "LAUNCH-VEHICLE" AND IS SO TREATED BY THE FAA. THIS REQUIRES ADDITIONAL REGULATOR COMPLIANCE THAN FOR A NORMAL AIRCRAFT TAKE OFF AND/OR LANDING. This is an IMPORTANT point to remember.

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This is just ridiculous, you're ignoring my point that there's a huge saving in using an existing super jumbo, the stability issues exist because these aircraft are not designed to carry hundreds of tonnes on their backs, the 747 Shuttle transporter had stability issues with the higher center of gravity of only the 70 ton Shuttle.
Number one, YOU assume that the vehicle has to be carried on the aircrafts back, "I" don't. Number two I'm not "ignoring" your point about savings with the use of "off-the-shelf" jumbo jets I am in fact AGREEING with it!

My point(s) about the relative stability and other issues was to point up the fact that even the MILITARY does not normally do tanker operations at "high" altitude or "high" subsonic speed. We in fact try to do the opposite at any given time because BOTH factors cause operational issues with the aircraft in flight due to neither being DESIGNED to do so for normal operations. The APT concept ASSUMES both tanker and Orbiter will be designed or modified to make this operation "easier" but this was never fully defined or thought out in the orginal concept.

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This is just bizarre, you play up the dangers of a routine operation like air to air refueling, but consider the actual seperation of two huge aircraft inflight as something that's relatively simple. it isn't, there's no way an orbiter of the size being discussed is ever going to be "dropped" from any version of any existing aircraft, it's simply impossible.
Your "assuming" again and you can see with the referenced papers that a significantly sized "vehicle" CAN be carried and dropped from under neath a "standard" jumb-jet airframe. You also assume a "winged" orbiter which isn't neccessary. And you also assume that modifications would not allow semi-recessed carry for a larger vehicle.

I'm pointing out "arguments" that you make to justify the concept are not neccesarilly true or supportive and that you MIGHT want to consider them in light of the facts and either revise them or drop them from the argument.

While we are at it, while APT has some advantages other methods such as "Towed" air-launch (which allows "Orbiters" almost twice the "mass" of the towing aircraft) has more but HAS operational disadvantages that have so far not been overcome. MY point is that operational advantages AND disadvantages have to be looked at and addressed not simply "brushed-off" with assumptions and misleading arguments.

It doesn't help the concept stand on its own.

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But you're talking a large developmental program for a specific air-propellant-transfer system. No matter HOW they evolve, (IF they do, which depends greatly on WHO developes and fields them :) ) the system is going to be based on a "single-source" customer: Themselves.
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Nope, I've no how you came up with any of that. Haven't the rockets flying today all evolved, aren't they still evolving?? Isn't the 747 still evolving?? Who said anything about a "single-source" customer (whatever that is)
The Space Shuttle never "evolved" into the fully resuable and cheap vehicle it was MEANT to be so no, "evolution" is NOT a given.

Your "Tanker" aircraft will be designed to operate with and for your "Orbiter" spacecraft. That's "single-source" customer. This does not preclude anyone who wants from desiging another "Orbiter" that can take advantage of your "Tanker" vehicle but there isn't a lot of "incentive" to do so, nor is there much incentive for you to allow other "customers" since this would take that "Tanker" capability away from your own operations.

"Evolution" of vehicle design takes a robust market and money, aircraft HAVE these resources, spacecraft do not.

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My own "pet" concept of attachable "booster" jet-pods for any spaceplane would be highly "compatiable" with any airframe that could mount the simple attachment points. "Wireless" control of the pods would give ANY spaceplane a "self-ferry" as well as highly flexible launch.
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Have you doe a post on your "pet" concept? There are a few issues I can see but I would need more details before commenting.
Yes, in an "Air-Breathing" or "Air-Launch" thread I'll have to look it up. And yes I'm pretty aware there are "issues" with the concept, and I'm always looking for more feedback :)
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I wait with baited breath to see how you're going to fit an orbiter capable of carrying a 15 or 20 tonne payload to orbit into, or under, an A380 or an AN225 or a 747-8.
Well we can START with the assumption that you "need" 15-20 metric tonnes of payload "on-orbit" in LEO...
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Not an "operational" issue until a SIGNIFICANT flight rate is achieved and there is no guarantee the same situation would not occur for APT operations as ANY issues with the Tanker automatically ground the Orbiter until and unless the flight operations pace is significant enough to allow multiple Tankers on stand-by for every flight.
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So your solution is to hope that "a SIGNIFICANT flight rate" is never achieved, brilliant!
Uh, no... Actually that's the current situation in a nut shell, but my point was that unless you have mutiple tankers/orbiters that are ALL ready to go at a moments notice the APT concept has the SAME operational issue as any other muti-part "concept" launch vehicle: Problems with ONE part means the system is grounded until repaired. Period.

APT does NOT get a "feebie" in any way as the Tanker and the Orbiter BOTH have to be working perfectly to achive the mission. You can't "argue" that APT is somehow "different" in this respect without explaining why and how it would "differ" from any other concept system. Since both the Tanker and Orbiter are NON-STANDARD vehicles you can not "assume" a great enough depth of equipment to allow for multiple back ups without explaining the extra costs involved.

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Almost any "Air-Launch" concept is capable of "self-ferry" so this isn't something that is enheirent only with APT.
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Name one air launched plane that had a proven self ferry capability. The ATP would have such an ability encompassed in its normal operations.
First please note that APT does NOT have a "proven" self-ferry capability. This is an ASSUMED not PROVEN capability. Why specifically? Well lets go back to the fact that your "Orbiter" is a SPACECRAFT/LAUNCH VEHICLE and NOT an "aircraft" so that any time it plans on "flying" anywhere it has to do so under FAA regulations requiring "cleared-airspace" from take off to landing within a specific window.

Could Spaceship-1 or Spaceship-2 "self-ferry" by using thier rocket engine? They sure could, except for two details:
1) They would have to file for and fly during the afore-mentioned FAA "launch-permit" which they DO NOT have to do when carried by the White-Knight carrier aircraft.
2) Landing gear: Both vehicles didn't have landing gear capable of holding the weight of the fully fueled vehicles though the margins are quite close.

So lets go back to showing "proven" self ferry again?
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Running to the FAA again, when regulations impede progress without good reason they need changing, you've not actually suggested that there's any good reason why an APT orbiter shouldn't self-ferry.
These regulations ARE the "new" regulations concerning vehicles with rocket-powerplants. Don't like em, then lobby to get them changed or deal with them. They are currently the "good-reason" why the APT Orbiter can't self ferry and you need to address that FACT.

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Further I'd point out that the AirLaunch LLC/T-Space concept the carrier aircraft is still capable of being used as an air-freighter or air-tanker (due to the modifications needed for use as a carrier aircraft) when not being tasked for launch operations. This allows the aircraft an additional 'revenue' stream beyond just launch operations. (This is actually a GOOD thing while waiting for flight rates to ramp up ;) )
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The revenue of even an A380 is peanuts compared to the current cost of  just one orbital launch, does NASA use its Shuttle carrier to move other stuff around?
Actually they have when it was not being used to ferry the Shuttle. And "revenue" is money when you're not launch vehicles so you may THINK of it as "peanuts" but anyone who has actually lived in the business world knows they have to constantly be looking for revenues to maintain the business.

Of course this shows you're missing your OWN point in that you expect APT to "lower-launch" costs yet you fall back to arguing that "current-launch-costs" give one the ability to make any other 'revenues' possible insignificant.
That would make sense I suppose if you weren't planning on lowering your profit, er... "cost" at all...

The truth is no matter how "low" your launch costs are predicted to be there is an inflexability in the launch market that has to be taken into account. There will be a period where there is more launch capability than requirement and therefore you might have months in between launches where (in your case) your system is sitting on the ground costing you money but making none in return. Meanwhile a "duel-use" airframe is still making at least SOME money during that 'down-time' which is something an investory looking at his ROI would take as a significant advantage.
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This issue is also possible with APT, but is not a "feature" of Air-Launch concepts in general. The bottom-mount AirLaunch LLC/T-Space system stages at around 12,000M (34,000+ ft)

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These repeated references to a small air launch system that isn't comparable to a 15-20 tonne payload APT are tiresome.
Which is it, 34,000+ ft or 12,000M? 12,000M is about 40,000ft.
Now who's "nit-picking" because he's got no counter-argument? :)
That should have probably been closer to 10,500m but still makes the point that not ALL Air-Launch concepts are limited in altitude.

Again though how big is your Orbiter to reach the altitude with a full propellant load AND the 15-20 metric tonnes of payload? And why so much payload in a single vehicle since higher flight rates help lower overall costs?

I'm going to cut this reply off here as it's gotten quite long and I think the next point needs expanding on.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #25 on: 06/30/2011 08:34 pm »
Epis.
There is nothing new in the idea of fully reusable TSTO the first shuttle concepts were exactly that, the only reason the shuttle wasn't done that way is cost. Developing an aircraft that can carry a cargo of hundreds of tonnes to high altitude at high speed costs tens of billions of dollars, the only reason I suggest that it can be done now is that most of the development has now been done, and it's been paid for by someone else.
True as far as it goes, but the 'sticking' point is the "method" at the moment. Using an "off-the-shelf" commercial aircraft is going to be be "cheaper" than a specially designed and built vehicle to be sure, HOWEVER the various modifications REQUIRED to turn that aircraft into a carrier vehicle OR a Tanker is going to cost also.
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Jim.
I don't think I'd need to look too hard to find examples of cryogenic systems that have extensions, retractions and rotations. How do they fuel the Shuttle on the pad? How do the motors gimbal? Are you suggesting that doing these mechanical operations as part of inflight refueling is going to be a show stopper?
Frankly, probably not a "show-stopper" but the costs of the modifications ramp up rapidly. In all your examples you forget that the majority are both short AND require only limited movement for the most part so extending these 'features' to feet or yards instead of inches is, yes, going to cost a lot to do. There are no real examples of FLIGHT hardware in the lengths and abilities needed and those will have to be developed.

It may or may not be "cost-effective" overall and then there is the operational elements that are still and unknown factor.

"Claims" are easy, evidence isn't so simple or straightforward.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Epis

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #26 on: 06/30/2011 10:09 pm »
True as far as it goes, but the 'sticking' point is the "method" at the moment. Using an "off-the-shelf" commercial aircraft is going to be be "cheaper" than a specially designed and built vehicle to be sure, HOWEVER the various modifications REQUIRED to turn that aircraft into a carrier vehicle OR a Tanker is going to cost also.
off-the-shelf aircraft will be cheaper but rocket size will always be low limited by available craft specifications and capabilities, so if rocket size is low 1-2 mt To LEO cargo carrying capacity, then cost of kg to LEO will be high, price won't come down, and that solution will stuck by commercial craft size availability, so limits are set there in using of the shelf craft. Even when modifying one of the shelf craft to take larger rockets putting more cargo to orbit, it still will be small improvement in term of payload price to orbit.
spaceX clearly show how simple laws of scalability can reduce cost by ~10X, so bigger rocket means cheaper payload to LEO, same will be true for airplane launch assist rockets so if rocket/plane combo cant scale to >50 mt LEO payload then I can easy say it wont be cheaper than spacX solution.
specialized craft is a way to go, example is virgin galactic WK2, and by the way plane building expenses from scratch were not so high, because technology is well known and there are of the shelf parts like engines, navigation, and so on, they just built plane frame, body and filled it with already made products. ground effect plane will be harder to build because its sort of rear technology, + adding mach ~2 capability will be even harder, I guess that will be ~~ >2x times expensiver than simple plane building, but it will be more rewording in long term, because of better scalability, that means heavier rocket launch assist thus lower cost to LEO :)
« Last Edit: 06/30/2011 10:09 pm by Epis »

Offline Andrew_W

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #27 on: 07/01/2011 09:56 am »
Hi RanulfC.

I couldn't get through on your second link.

Your first link did a pretty good job of justifying my skepticism of air launch, it was clear that air launch cannot accommodate anywhere near as large a payload as can be carried with APT from any given airliner.

Your link didn't give a figure for payload to LEO, though I'd estimate it's about 5 tonnes, and as far as I could see there was no suggestion of reusablity other than for the 747 (obviously) and the proposed Manned capsule, the rest of the rocket was throw away, and it's that use expensive hardware only once approach that we need to get away from if the cost of space access is to get below ~$1,000/kg.

Your link made it clear that there was no way that anything larger could be carrier under the 747, and this restriction also means that only denser fuel/oxidizer combinations are possible.

 
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Well we can START with the assumption that you "need" 15-20 metric tonnes of payload "on-orbit" in LEO...

That's the bare minimum for a cargo carrier as most things needing to go to orbit are at least that size, a point Jim made earlier.

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And you also assume that modifications would not allow semi-recessed carry for a larger vehicle.

there won't be any semi-recessed orbiters carried on  versions of existing airliners as that would make the wings fall off of the airliner.

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APT does NOT get a "feebie" in any way as the Tanker and the Orbiter BOTH have to be working perfectly to achive the mission. You can't "argue" that APT is somehow "different" in this respect without explaining why and how it would "differ" from any other concept system.

You would be looking to operate a ratio of orbiters to tankers, a tanker could fly at least once a day, the orbiter would have a turn-around time of at least two days.

The cost to orbit of hundreds of dollars/kg is low enough to encourage considerable market growth, there has been analysis of market growth especially in terms of tourism that points to a market in the hundreds of thousands of passengers/yr if the price of a ticket can be brought down to $100,000.

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First please note that APT does NOT have a "proven" self-ferry capability. This is an ASSUMED not PROVEN capability.

The Apt orbiter can take-off from a runway, fly by itself, and land on a runway, it has to be able to do these things to operate as an APT orbiter, self ferry requires NOTHING outside of these normal operational abilities.

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That should have probably been closer to 10,500m but still makes the point that not ALL Air-Launch concepts are limited in altitude.

Your link was very informative in just how badly the aerodynamics of an airliner are affected by carrying external cargo, it's only when the cargo is quite small relative to the airliner that normal operational altitude is attainable.

Regarding the cost of modifying airliners for APT vs air launch, both costs need to be put in the context of the system overall cost and performance of the complete system. What I envisage for APT is a system that recreates, as much as is possible, the type of operation as is conducted by airliners in moving people and freight around the globe, the air launch system you're promoting is more like competition for the SpaceX system, in its way it might be good, but it's a generation behind fully reusable systems like APT and Skylon.
I confess that in 1901 I said to my brother Orville that man would not fly for fifty years.
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Offline Andrew_W

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #28 on: 07/01/2011 10:01 am »
Epis:
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spaceX clearly show how simple laws of scalability can reduce cost by ~10X, so bigger rocket means cheaper payload to LEO, same will be true for airplane launch assist rockets so if rocket/plane combo cant scale to >50 mt LEO payload then I can easy say it wont be cheaper than spacX solution.

Something like 90% of the cost of a SpaceX launch is in the value of the hardware thrown away, not having to throw that hardware away could reduce cost to orbit by at least 80%.

APT does have an advantage is scalability over air launch.
I confess that in 1901 I said to my brother Orville that man would not fly for fifty years.
Wilbur Wright

Offline Jim

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #29 on: 07/01/2011 11:42 am »

Jim.
I don't think I'd need to look too hard to find examples of cryogenic systems that have extensions, retractions and rotations. How do they fuel the Shuttle on the pad? How do the motors gimbal? Are you suggesting that doing these mechanical operations as part of inflight refueling is going to be a show stopper?

None of those things you mention have anything in common with a refueling boom.

The engine feed lines have bellows.

A refueling boom telescopes

Offline Andrew_W

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #30 on: 07/01/2011 08:55 pm »
Is there some point to this focus on the refueling boom? If telescoping cryogenic tubes are some insurmountable problem, which I doubt, you can use bellow tubes inside a sheath with hydraulic cylinders to extend it. The major challenge for an APT system is going to be the design and construction of the orbiter, that'll be into the billions, even if it's done privately, the modifications to an A380 and design of a boom to provide an adequate tanker will be far less expensive and challenging.

Maybe the focus of skeptics is on the tanker not because it's so hard, but because the orbiter is so similar any other reusable orbiters that have to propel themselves part of the way to orbit with on-board fuel, so any challenges of the feasibility of the orbiter are challenges to many skeptics own pet ideas.
I confess that in 1901 I said to my brother Orville that man would not fly for fifty years.
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Offline Jim

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #31 on: 07/01/2011 09:16 pm »

Maybe the focus of skeptics is on the tanker not because it's so hard, but because the orbiter is so similar any other reusable orbiters that have to propel themselves part of the way to orbit with on-board fuel, so any challenges of the feasibility of the orbiter are challenges to many skeptics own pet ideas.

I can twist your words to the opposite.  You are so hard over fanatic for this concept that you automatically dismiss any challenge, yet you haven't provided any data nor do you have the credibility from experience to back your claims.

Offline Andrew_W

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #32 on: 07/01/2011 09:41 pm »
I've looked at just about every system to reduce cost to orbit, and I've had lots of favorites at one time or another, I'm not going to stick with any one method in the face of evidence of it having some major shortcoming compared to another, so if you think APT has some disadvantage that would make it less economical than another (lets assume say 10,000-100,000 tonnes/yr to orbit) convince me, trying to claim that cryogenic refueling booms are just tooo :-[ hard isn't going to cut it.
I confess that in 1901 I said to my brother Orville that man would not fly for fifty years.
Wilbur Wright

Offline Jim

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #33 on: 07/02/2011 02:04 am »
I've looked at just about every system to reduce cost to orbit, and I've had lots of favorites at one time or another, I'm not going to stick with any one method in the face of evidence of it having some major shortcoming compared to another, so if you think APT has some disadvantage that would make it less economical than another (lets assume say 10,000-100,000 tonnes/yr to orbit) convince me, trying to claim that cryogenic refueling booms are just tooo :-[ hard isn't going to cut it.

Too small of payload is negating it

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #34 on: 07/02/2011 02:37 am »
If you want the benefit of lower per flight costs of a fully reusable system you either have to settle for a smaller payload or get someone to front up with well over ten billion dollars to invest in it (unless you've got a system that requires a modest capital investment, carries a large payload, and has low per flight costs?), APT is the only system I know of with what I think are manageable capital costs and what I think is a reasonable payload to LEO, and it's achievable only because super jumbo's already exist.

Possibly a 25 tonne payload could be carried to orbit using APT if the orbiter was fully fueled at take-off and the refueling at altitude only replaced was was burnt to get to 12,000 meters, or if as MarkZero suggested two tankers are used to refuel, but then you're talking about a much bigger investment in a much bigger orbiter that has to cope with greater take-off and aerodynamic loads. Such an approach would, if past attempts to develop fully reusable systems are anything to go by, find it impossible to get the required capital funding.

We can dream all day about the US taxpayer footing the bill for the fully reusable system that the Shuttle should have been, but it ain't gonna happen.
I confess that in 1901 I said to my brother Orville that man would not fly for fifty years.
Wilbur Wright

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #35 on: 07/02/2011 02:49 am »

We can dream all day about the US taxpayer footing the bill for the fully reusable system that the Shuttle should have been, but it ain't gonna happen.

Who says anything about about the taxpayer.


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Re: Aerial Propellant Transfer re-usable launch system
« Reply #36 on: 07/02/2011 02:51 am »

Possibly a 25 tonne payload

You have yet to show that this is feasible


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Re: Aerial Propellant Transfer re-usable launch system
« Reply #37 on: 07/02/2011 02:53 am »
APT is the only system I know of with what I think are manageable capital costs and what I think is a reasonable payload to LEO, and it's achievable only because super jumbo's already exist.


It is not an 'existing" system, you have yet to prove that it can exist.

Also, who is "I"?  It is news to me where New Zealand is a haven of companies dealing with space launch or an unusual concentration of experienced engineers dealing with the same subject. 
« Last Edit: 07/02/2011 03:07 am by Jim »

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #38 on: 07/02/2011 02:59 am »
If you want the benefit of lower per flight costs of a fully reusable system you either have to settle for a smaller payload

what benefit?
lower per flight costs are meaningless if the payload mass isn't there.  15 to 30klb to GTO is what is needed.

Current systems are cheaper for current flight rates.


This isn't EELV with propellant depots vs HLV.
This is VW's vs tractor trailers.
« Last Edit: 07/02/2011 03:03 am by Jim »

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Re: Aerial Propellant Transfer re-usable launch system
« Reply #39 on: 07/02/2011 04:12 am »
Quote

Who says anything about about the taxpayer.


Well, if a someone else wants to front up with tens of billions of dollars on a fully reusable launch system that would be great, but that hasn't happened lately either.

Quote

lower per flight costs are meaningless if the payload mass isn't there.  15 to 30klb to GTO is what is needed.


Most versions of Ariane 5 can't put 15klb into GTO, but they use them anyway, Falcon 9 can't put 15klb into GTO, but they built it anyway, most versions of Delta IV medium can't put 15klb into GTO, but they use them anyway.
There are still plenty of LEO flights of less that 15 tonne payload.
http://en.wikipedia.org/wiki/Comparison_of_mid-heavy_lift_launch_systems
Quote
Current systems are cheaper for current flight rates.


On what do you base that claim?

Quote
It is not an 'existing" system, you have yet to prove that it can exist.

I don't recall calling it an " 'existing" system", so if you can point to where I made such a claim, I'll certainly apologize.

Jim, maybe you've lost your way here, this is "Advanced Concepts" hardly any "Advanced Concepts" are actually flight proven, it's just the way it works, if only "proven" "Advanced Concepts" were discussed at  "Advanced Concepts" there wouldn't be too much discussion here because once a system is "proven" it's no longer an  "Advanced Concept".

Quote
Also, who is "I"?  It is news to me where New Zealand is a haven of companies dealing with space launch or an unusual concentration of experienced engineers dealing with the same subject. 

I'm sorry, I don't understand the reason for the question, "who is Jim?" isn't a question I'd ask because it's irrelevant, what counts is the content, not the source.
« Last Edit: 07/02/2011 04:24 am by Andrew_W »
I confess that in 1901 I said to my brother Orville that man would not fly for fifty years.
Wilbur Wright

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