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Old 12-20-2011, 01:05 AM   #61
C3PO
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Quote:
Originally Posted by T.Neo View Post
 Depends on how severe a dog-leg you fly.
Try it.
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Old 12-20-2011, 10:45 AM   #62
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Try it.
Depends on how severe a dog-leg you fly.

From what launch site? To what orbit? With what vehicle? At what point in the flightpath?
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Old 12-20-2011, 04:07 PM   #63
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Originally Posted by T.Neo View Post
 Depends on how severe a dog-leg you fly.

From what launch site? To what orbit? With what vehicle? At what point in the flightpath?

Your choice, any site, any target, any vehicle. Just try launching out of plane.
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Old 12-20-2011, 04:17 PM   #64
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Just try launching out of plane.
Are you trying to be facetious?

If you are so desperate to prove that it is impossible, show it yourself.

Last edited by T.Neo; 12-20-2011 at 04:20 PM.
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Old 12-20-2011, 09:28 PM   #65
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Originally Posted by T.Neo View Post
 If you are so desperate to prove that it is impossible, show it yourself.
Progress --> ISS

Worst case would be a 22.5° plane change, so let's use ~50% of that: 11°

DV: 1380 m/s

Extra fuel for plane change: 3618 kg

Max payload 2350 kg

Payload reduction: 154%

The calculations include negative mass for payload, so you would have to add larger fuel tanks to make it to ISS.

Then you need to include the increased gross mass to all the orbital maneuvers, so I'm guessing the final number would be closer to 200% payload reduction.

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Old 12-20-2011, 09:32 PM   #66
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Worst case would be a 22.5° plane change, so let's use ~50% of that: 11°

DV: 1380 m/s

Extra fuel for plane change: 3618 kg

Max payload 2350 kg

Payload reduction: 154%

The calculations include negative mass for payload, so you would have to add larger fuel tanks to make it to ISS.

Then you need to include the increased gross mass to all the orbital maneuvers, so I'm guessing the final number would be closer to 200% payload reduction.
Wait, you're talking about a plane-change on orbit, done by the propulsion onboard the spacecraft itself?

I'm talking about flying the launch vehicle sideways to change inclination as was performed on some Shuttle and Delta II flights.
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Old 12-20-2011, 09:37 PM   #67
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 An aggressive rendezvous has nothing to do with launch location but rather the amount of dV expended in orbit. And it is a trade-off: do you want a shortened rendezvous time, if it results in even a 50% payload reduction?
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Originally Posted by T.Neo View Post
 Wait, you're talking about a plane-change on orbit, done by the propulsion onboard the spacecraft itself?

I'm talking about flying the launch vehicle sideways to change inclination as was performed on some Shuttle and Delta II flights.
Can you please make up your mind?
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Old 12-20-2011, 09:39 PM   #68
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Can you please make up your mind?
I made my mind up a long time ago, but I didn't clarify that my envisioning of an "aggressive rendezvous" assumed that the spacecraft and its target were more or less in the same plane.
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Old 12-21-2011, 12:52 AM   #69
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Calculating dog-leg during ascent is a bit too complex for me. (for this discussion anyway) But I doubt that any existing launcher will make it into orbit, even without payload, if the target plane is more than a few degrees off.

Quote:
.... assumed that the spacecraft and its target were more or less in the same plane
That is the way we do things now using launch sites. But the target may be in the wrong position for a direct ascent by the time the launch site is in-plane.

By using a plane as a first stage it's possible to fly out to the location where you're in-plane at the same as the target is at the optimal TrA.

A winged first stage does this kind of maneuver much more efficiently than a ballistic one.
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Old 12-21-2011, 02:30 PM   #70
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While I don't have hard numbers yet, in order for the shuttle to perform a 'dog-leg' maneuver, NASA was planning to utilize five segment SRBs or Liquid boosters (all the way up to STS-107 when the 5-seg SRB was finally nixed from the SSP). This would have allowed acceptable payload to a south-north polar orbit or 20,000 lb more payload to an ISS-inclination orbit. I haven't found any info on if the shuttle would be able to perform the maneuver empty but what is the point of an empty space shuttle?

My opinion is, there are too many unknowns in the system to make a definitive conclusion. Personally I like the idea of air launching an orbit bound payload. But the advantages and disadvantages have yet to be explored in real world conditions yet. I'll wait until they produce some hardware
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Old 12-21-2011, 04:05 PM   #71
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Originally Posted by zerofay32 View Post
 My opinion is, there are too many unknowns in the system to make a definitive conclusion. Personally I like the idea of air launching an orbit bound payload. But the advantages and disadvantages have yet to be explored in real world conditions yet. I'll wait until they produce some hardware
That's exactly why I'm excited about this project.
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Old 12-21-2011, 04:39 PM   #72
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Originally Posted by Hielor View Post
 - I can't be the only one thinking "go around, go around" on that landing video--way too high and fast, and they ate up a ton of runway in the roundout and flare...
I was nearly screaming
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Old 12-22-2011, 05:43 PM   #73
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That is the way we do things now using launch sites. But the target may be in the wrong position for a direct ascent by the time the launch site is in-plane.
I never suggested doing a direct ascent, rather doing a 'traditional' ascent with more 'dV expensive' manuvers to catch up to the target in a reduced period of time.
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Old 12-22-2011, 08:53 PM   #74
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I guess if the huge carrier aircraft could be used to also carry oversized air cargo then the concept might be finnancially viable. An 225 is used quite often to carry heavy machinery to remote regions. If a runway can handle the An 225 then it also should be able to handle this plane since the weight is quite similar.
That way they could avoid the poblem of spending hundreds of millions of $ on a new aircraft that is used only few times per year.
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Old 12-23-2011, 03:29 PM   #75
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Parabolic Arc: Stratolaunch Extends Northrop Grumman’s Commercial Space Portfolio:
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NGC PR — REDONDO BEACH, Calif., Dec. 22, 2011 — Northrop Grumman Corporation expanded its commercial space portfolio with Stratolaunch Systems’ recent selection of Scaled Composites, a Northrop Grumman subsidiary, to build the largest aircraft ever constructed. This is the latest example of the company’s innovative solutions to challenging problems. Scaled Composites is developing an air-launch system for Stratolaunch Systems, which is a Paul G. Allen project that will revolutionize space transportation by providing orbital access to space at lower costs, greater safety and increased flexibility.

“This private spaceflight initiative represents a significant leap forward in defining technologies today which will open doors tomorrow for affordable commercial space transportation,” said Paul Meyer, vice president and general manager of advanced programs and technologies for Northrop Grumman Aerospace Systems. “Whether it be manned and unmanned aircraft, space systems or advanced technologies, we are focused on developing innovative solutions that enable the growth of the aerospace industry.”

{...}
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