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An-225 as white knight?

Posted by: Alessandro - Fri Nov 26, 2004 3:49 pm
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An-225 as white knight? 
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Post    Posted on: Sat Dec 04, 2004 6:08 pm
The best and easiest upgrade of the AN-225 would be to replace the Progress engines with either RR or GE engines, towing wouldn´t be a good idea due to AN-225 size, create vortex behind the ship that are huge.

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Post    Posted on: Sun Dec 05, 2004 4:28 am
What is it with the enormous anti-airplane mentality that almost everyone here seems to have? Didn't any of you people like planes at some point, did any of you ever want to be pilots? Moot points for sure, but airplanes are very mature, efficient machines, which is more than launch vehicles can say for themselves and they are fundamentally better suited to space flight. No one has ever really developed a pure space vehicle, all launch vehicles are either airplanes adapted for spaceflight (X-15, SS1) or artillery pieces adapted for spaceflight (Atlas, Delta, etc). Of the two, airplanes are simply better suited for carrying people than weapon systems.

Let's stop and think about what a rocket does to fly and what an airplane does to fly. Even though Earth's atmosphere carrys an ample supply of oxygen from the ground to about 60,000 feet, rockets fight this atmosphere all the way and carry thier own oxygen with them from the ground up. Rockets use brute force and have to fight the atmosphere every inch to orbit. By contrast planes don't fight the atmosphere, they use it to their advantage. Takeoff requires much lower amounts of fule if the engine only has to supply enough horizontal speed for the wings to take over and the wings can actually be used as fuel tanks themselves. If you designed a rocketplane properly the wings would only be a very small weight penalty and would give the launch vehicle a huge atvantage over a conventional rocket in delta V requirements.

Air launch is even better from an ease-of-specification standpoint. Having a completely seperate vehicle take care of the first km/s or so of delta V required to achive orbit can give giant bonuses to the allowable mass ratio of the launch vehicle. As long as the rocketplane itself is under 400,000 pounds it should be entirely possible to build a carrier plane that can take it up to 40,000 feet or so (White Knight with 777 engines, anyone?). It might not be as good from an infrastructure standpoint but it makes the design go a lot smoother. Besides, do I need to remind you people what kind of architecture the X Prize winners used? Honestly, a good system that works is right there in SpaceShipOne and there are still legions blindly worshiping Armadillo at the VTVL altar. If Armadillo ever does reach space they'll only end up with a system that's an intellectual and commercial dead end. SpaceShipOne is the way to go.

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Post    Posted on: Mon Dec 06, 2004 9:19 am
Personally i have nothing against an air launch system.
Do I think that its the best system? No
Air launch has its adavntages as you state, however its not without its draw backs, as any system.
The simple reason that airlaunch won the Xprize comes down to the fact that scaled had the experience with allen providing the capital, end of story.
It would have made little to no sense for scale to go with a VTVL system, its not their area, and they have loads of experince with wings.
In a way what scaled did was make a TSTSO system, while Armadilo went with a SSTSO, which is a harder build.
While wings in atmosphere do give a benefit in the area of dV, they also suffer from extended time in the atmosphere (drag). You also suffer from the requirement of 2 entirely seperate vehicles, of completely different design, to build and test. What percentage of Scaled's budget went on WK? I dont personally know, but I would be willing to be that it was a fair proportion. Jet engines arent cheap, niether are the avionics, or the extra personell required to fly the ship. While Im busy speculating, I would be willing to bet that WK comprised more than 50% of the budget.
Im not going to get into the penatlies of wings and gear, I think that which ever system that you use will have its own draw backs, theres no one system that stands head and shoulders above the others, hence why we see so many vehicle modes.


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Post    Posted on: Mon Dec 06, 2004 9:49 am
According to the budget spent on Wight Knight there seems to be an aspect overseen up to now.

After releasing SSO at launch altitude Wight Knight at once returns to the spaceport while SSO is going to space. If the turn-around-time could be reduced to an hour or so the Wight Knight could carry a second SSO to launch altitude while the first SSO still is on its flight (returning to the spaceport perhaps.

Now with Wight Knight and SSO this probably will not be possible but Scaled may include many improvements into Branson's vehicles too reduce turn-around-time as much as possible. Branson as well as Scaled will be interested in that for commercial and other economical reasons. So if Branson's vehicles too will be two-stage-vehicles there may be five second-stage-vehicles but only one to three first-stage-vehicles.

In this case a two-stage-air-launch could prove to be economical advantageous.

Have Scaled, Rutan or Branson clearly and unmisunderstandable clarified that Branson's vehicles will be single-staged? I never read that.



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)

EDIT: The last question has been clarified now by the article "One small step for space tourism Dec 16th 2004, The Economist print edition If plans for a new range of suborbital vehicles get off the drawing board, then holidays in space could get off the ground" ( http://www.economist.com/science/displa ... id=3500237 ) which says that "... There will also be a new “mother” aircraft to take them to high altitude prior to their launch into space. ..."

So Branson's vehicles will be double-staged. Additionaly the quote sounds as if the will be only one first stage but we should wait for additional informations.


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Post    Posted on: Thu Mar 10, 2005 7:06 pm
AN-225 would be a perfect C-5 A Galaxy replacement if put into production with 777 engines. It could launch REAL spaceships like HOTOL MAKS, Svityaz, etc.


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Post    Posted on: Thu Mar 10, 2005 8:41 pm
Keep in mind that there is very little benefit to be gained from using an air launch for orbital craft, as opposed to sub-orbital ones. (This is with regards to the "real" spacecraft comment)

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Post    Posted on: Thu Mar 10, 2005 10:01 pm
Sev wrote:
Keep in mind that there is very little benefit to be gained from using an air launch for orbital craft, as opposed to sub-orbital ones. (This is with regards to the "real" spacecraft comment)


These guys would disagree with you. So would These guys. Do you know something that they don't?


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Post    Posted on: Thu Mar 10, 2005 11:27 pm
skybum wrote:
Sev wrote:
Keep in mind that there is very little benefit to be gained from using an air launch for orbital craft, as opposed to sub-orbital ones. (This is with regards to the "real" spacecraft comment)


These guys would disagree with you. So would These guys. Do you know something that they don't?


I might point out that those websites are both talking about launching very very small vehicles. 1000 pounds is tiny; a vehicle capable of taking enough people to orbit to be practical would weigh in at several tons.

And besides, if you people would just read the AIAA paper provided here, then you'd see a few of the problems with an ALHL system (aerial launch, horizontal landing). Note: don't try to access the paper through the new X Prize website, the link doesn't work.

And just so you know, Senior Von Braun (how can you take that name and argue against rockets? :wink:), the Gemini was a true orbital vehicle, in every sense of the word.

Finally, I have to agree with SawSS1Jun21: bigger and faster is definitely better. I've had the chance to get up close and personal with the lone remaining Valk, and she's definitely a sight to behold.

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Post    Posted on: Fri Mar 11, 2005 6:22 am
I read that paper when it first came out, and wasn't particularly impressed with it at the time. I'm still not. It is riddled with errors, the most fundamental being that it derives makes most of its conclusions from historical models, which is perhaps the worst way to analyze emerging technologies. Thus it arrives at fallacious conclusions like (to paraphrase): "Winged VTHL is the best option, because the Space Shuttle and Buran have proven that it works" and "Air Launch is the second best option, because the X-15 has done it". Which is roughly like saying that the Vikings have proven that wooden longships are the best option for crossing the Atlantic.

Furthermore, when it bothers to do technical analysis at all, it doesn't even begin to look at possible tradeoffs between physical efficiency and operational simplicity. This is hardly a unique problem; it's pandemic among aerospace engineers. But the fact is that oftentimes the vehicle with a lower mass fraction may in fact be the far superior vehicle, if it has a lower part count, a quicker turnaround time, reduced infrastructure requirements, a much smaller support crew, or more recoverable abort modes. Any study which fails to account for all of these factors should not be taken too seriously.

I can't really fault the authors, though. History is littered with innumerable assertions that something can't be done, simply because it hasn't been done, shortly before it is done. This kind of short-sightedness seems to be a basic human trait. (Note that I fully concede that there are many flaky ideas out there which indeed won't work -- it's just that using the "no precident" argument to explain why is entirely fallacious.)

By the way, Airlaunch LLC has talked about launching payloads as large as 10,000-12,000 lbs using existing hardware (Zenits and Anatovs, I believe -- although I know that there is a Russian outfit which has proposed something similar, and I may be conflating the two). Their FALCON proposal was just a convinient launching point, so to speak.


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Post    Posted on: Fri Mar 11, 2005 10:41 am
There is one simple and - to me - convincing reason for air-launch Burt Rutan mentioned - safety of the passengers.

If a spacecraft is to be constructed that shall carry tourists and other civilian people to the orbit or to another planet then safety is a major topic - especially with regard to the recently passed bill that is under discussion for modifications currently.

So this is a point for air launch.

The other arguments - weight, thrust, propellent -are points for groung launch and/or vertical launch.

This means that there at least two approaches which seem to be in conflict to each other at the first glance. But in the Technology section it may be possible to look for possible combinations of the two approaches by discussion (May be I will start one) Something far similar is included in the CEV-concept of t/Space - the launch the CEV to orbit first, then let follow tankers to fuel the CEV and then launch to the moon.

I would like to see a thread in the Technology section that explores each way, possibility, method, approach, idea how to combine the two approaches - reagrless how silly and idea may be. Perhaps a third approach appears one day that too will have to be included there.

skybum,

you are completely right concenring "something can't be done because it hasn't been done never before" and the like - I know all that very well. It's frsutrating and bad and sometimes used to prevent and bar something for political or egoistic reasons or to keep life simple for the author(s) of it to the burden of the others.

It would be a good topic to be discussed in the Off Topic section to think about objective Pros and Contras and it may be good topic in the Technology section too to think about how to act in development if something hasbn't been done yet or if one is barred by the "hasn't been done yet"-argunment.

I would like to see both these discussions - the one in the Off Topic section AND the one in the Technology section.



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Post    Posted on: Fri Mar 11, 2005 7:46 pm
Ok, a clarification of points.

From a physics/economics reason, there is no reason to launch an orbital rocket from the air.

If you were going to try and put forward the case for orbital air-launches, I certainly wouldn't use some unknown, under-funded startup company. I would cite Orbital's Pegasus as a much better example.

So yes, there is a precedent for pre-existing, air-launched orbital rockets. But that doesn't make it cheaper (it is the most expensive launch system in the world right now, after the Space Shuttle), or any more effective. The main reasons Orbital did this, were as follows:

They wanted to provide a next day launch service for small satellites. This can only be done using solid fueled rockets, since liquid rockets take too long to prepare and fuel up. This problem also continued to launch pads, which are expensive to keep prepped (although the overhead is a lot lower for solid rockets). The other problem was that they wanted to be able to provide this service over a wide area, and to be able to launch into any conceivable orbit.

Since the rocket they were building was very small, this allowed for them to make it launchable from a large plane.

A final problem is that it is only really possible to launch a very small rocket. Considering that in an orbital rocket, there must be over 10 times as much fuel as payload, to launch a 10,000 lb payload would take around 100,000 lbs of propellant. I'm not certain, but I believe that is considerably greater than the maximum capacity of a B-52.

So yes, it is possible. But there really is little reason to, unless you're providing a "service" of conveinence, rather than an economic and effective launch method.

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Post    Posted on: Sat Mar 12, 2005 9:39 am
Hello, Sev,

Ithat's clarification of positive kind.

Concerning combinations of air launch with vertical launch I didn't have in mind a Pegasus-like method. There may be others too - it would be worth a thread in the Technology section really. I'm still thinking about it.



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Post    Posted on: Fri Mar 18, 2005 4:59 pm
Just to play a little devil's advocate here...

B-52 weapons paylod capacity: 70,000 lbs.
http://www.fas.org/nuke/guide/usa/bomber/b-52.htm

internal fuel capacity 46000 US gallons
http://www.danshistory.com/b52.html

Jet fuel weighs approximately 62.5% of the weight of water.
http://www.grc.nasa.gov/WWW/K-12/BGP/PA ... r2_act.htm
(at .625 x 8 lbs per US gallon, I get 5 lbs/gal)

Since you don't have to travel 8000 miles to deliver your payload, you can ditch a paltry 15% of your fuel and you have an operational payload capacity of approximately 100,000 lbs. Never say "it can't be done" (or even "it shouldn't be done")

People are going to keep building Air-Launch-to-Orbit ships, and they'll keep getting bigger. Only time will tell if they are economically feasible in open competition against the other technologies out there. As long as someone wants to foot the bill without using tax money, I say let 'em try anything.


Last edited by SawSS1Jun21 on Fri Mar 18, 2005 6:13 pm, edited 1 time in total.



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Post    Posted on: Fri Mar 18, 2005 6:03 pm
Hello, Sev,

It's arepetition of the hint - but what about the air launch concept of JP Aeropsace?

They plan to do air launch at 42 km altitude but it's quite different to Rutan's air launch. The JP Aerospace air launch seems to be quite similar to the air launch as designed by ILAT or da Vinci.. - but the JP Aerospca air launch is quite different to the conspets of these both too it seems:

ILAT and da Vinci let their ballons go to altitude carrying the vehicle with them. At the desired altitude the engine, the rocket of the vehicle is ignited.

JP Aerospace instead uses an ion drive - not a rocket. The concept of JP Aerospace's ATO is using a vehilce that has a very large wing - very much larger than the wings of SSO. When launching from the Dark Sky Station or the floating port(s) ATO wouldn't fall down to Earth - and it wouldn't plung into the atmosphere at reentry. Even because of that wings. I don't remember the properties of the wings of ATO - I am going to start a thread about thm in JP Aerospace's General Forum - but they may be similar to the air chambers of DSS and the Ascender.

What about that air launch? Or don't you call that an air launch?



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Post    Posted on: Fri Mar 18, 2005 6:54 pm
lol. Yes, it is possible to launch using an airplane, of course it is. But for an orbital craft, it is really necessarily a good way to do it? I somehow doubt it.

A fully fueled Atlas V rocket weights more than a 747, no plane ever conceived could possibly carry it. Combine this with the fact that you don't really benefit for orbital craft that much, and you begin to understand why it's only ever been used for micro-launchers (meaning the Pegasus).

JP Aerospace was a sub-orbital flight company, and yes, as Scaled Composites showed, using air-launch for sub-orbital flights is very effective. But the physics simply isn't the same for orbital flights.

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