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  #11  
Old 06-02-2017, 06:15 PM
Jerry Irvine's Avatar
Jerry Irvine Jerry Irvine is offline
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I suggest the government have 2-3 alternative suppliers.
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  #12  
Old 06-02-2017, 06:45 PM
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I don't know if redundancy was part of the thought process for the design, but with separated horizontal stabs, a fubar'd payload release might just hit one stab and leave the other side intact. It might be enough to get the now empty plane back to the ground. With the booms connected by a solid stab, there is a bigger target to hit and ripping of the solid stab would likely damage both booms and control systems.
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  #13  
Old 06-04-2017, 08:53 PM
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Quote:
Originally Posted by blackshire
Air launching provides several advantages that are well worth making use of. The vehicles can use considerably lower-powered first stage rockets because the vehicles are launched horizontally rather than vertically, and wings (such as those on the Pegasus first stage and on air-launched space planes) can assist the ascent trajectory. Such shallow ascent trajectories also greatly reduce the gravity losses on the climbing vehicles.
Plus, the first stage nozzles of stratosphere-launched rockets can be vacuum-optimized for maximum efficiency, and the high subsonic velocity imparted by the launch aircraft gives the vehicles a significant "head start." In addition:

Despite its higher-than-hoped-for unit cost (which its relatively low launch rate, and the high maintenance costs for its old Lockheed L-1011 launch aircraft, combine to cause [its launch rate is gradually increasing as satellite miniaturization becomes easier]), NASA and other users like Pegasus because of the other advantages of air-launching:

The launch times (launch windows) and drop locations are flexible, countdown recycles--with or ^without^ having to land between launch attempts--are easy, right up until the single-use fin actuator batteries are activated seconds before drop (the plane flies a "racetrack" pattern while setting up for the next drop attempt), and Pegasus can literally "come to the customer" for payload integration, which greatly simplifies logistics and saves a lot of money for the satellite owner(s). For smaller space agencies and private satellite firms, this is no small convenience. The importance of this particular advantage became clear when Pegasus launched its first international payload, a Spanish scientific satellite (see: http://www.google.com/#q=Pegasus+wa...+Canary+Islands ), which involved having the L-1011 take off from the Canary Islands.

Up until now, the available launch aircraft have been rather marginal. Over the years, larger expendable air-launched SLVs (and reusable air-launched winged orbital spacecraft) have been designed by Richard Salkeld, Len Cormier, Dan DeLong, Boeing, Teledyne Brown Corporation, and others, but the lack of "stock" aircraft with sufficient performance and structural margins was a large factor in keeping these air-launched designs confined to drawings. (To give two examples, Teledyne Brown's space plane was designed for launch from the back of a 747, but its range and loiter time were very limited, while a Boeing space plane design required its 747 carrier to incorporate a Space Shuttle Main Engine in its tail to provide a boost at launch!)

With a large, "universal" flying launch pad now available, these and other expendable and reusable air-launched space vehicles will now be not just feasible, but practical.


Yeah, I get all that... but air launch of a LIQUID PROPELLANT rocket is something else indeed.

Pegasus is solid fuel. Everything else I've seen air launched is solid propellant. Liquid propellant adds a whole different dimension, if only from sloshing of propellants, especially on the size rocket they were talking about launching.

So are they talking about solid propellant rockets now? I don't really follow Stratolaunch-- I don't find it particularly interesting.

I can see airborne launch for small payloads, for larger payloads, I'm not sold. I think it's a solution in search of a problem. I guess time will tell.

Later! OL J R
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  #14  
Old 06-04-2017, 09:37 PM
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Quote:
Originally Posted by luke strawwalker
Yeah, I get all that... but air launch of a LIQUID PROPELLANT rocket is something else indeed.

Pegasus is solid fuel. Everything else I've seen air launched is solid propellant. Liquid propellant adds a whole different dimension, if only from sloshing of propellants, especially on the size rocket they were talking about launching.

So are they talking about solid propellant rockets now? I don't really follow Stratolaunch-- I don't find it particularly interesting.

I can see airborne launch for small payloads, for larger payloads, I'm not sold. I think it's a solution in search of a problem. I guess time will tell.

Later! OL J R
The latest illustrations show a triple-adapter, with three Pegasus vehicles mounted under the Stratolaunch aircraft's wing center section.
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  #15  
Old 06-10-2017, 08:20 AM
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Quote:
Originally Posted by luke strawwalker
Yeah, I get all that... but air launch of a LIQUID PROPELLANT rocket is something else indeed.

Pegasus is solid fuel. Everything else I've seen air launched is solid propellant. Liquid propellant adds a whole different dimension, if only from sloshing of propellants, especially on the size rocket they were talking about launching.

So are they talking about solid propellant rockets now? I don't really follow Stratolaunch-- I don't find it particularly interesting.

I can see airborne launch for small payloads, for larger payloads, I'm not sold. I think it's a solution in search of a problem. I guess time will tell.

Later! OL J R
Here is why I think Stratolaunch may have a much larger influence on private space operations that is immediately apparent:

In his essay "Next--The Planets!" in his 1972 book "Report on Planet Three and Other Speculations," Arthur C. Clarke wrote the following, which occurred to him in response to Dr. Simon Newcomb's declaration that a heavier-than-air flying machine could never carry a passenger as well as a pilot (the astronomer had recently asserted that such flying machines were totally impossible--just months before the Wright brothers flew at Kitty Hawk):

"Now I am not trying to poke fun at one of the greatest of American scientists. When you look at the Wright biplane, hanging up there in the Smithsonian Institution, Newcomb's attitude seems very reasonable indeed; I wonder how many of us would have been prepared to dispute it in 1903.

"Yet--and this is the really extraordinary point--there is a smooth line of development, without any major technological breakthrough, from the Wright 'Flyer' to the last of the great piston-engined aircraft such as the DC-6. All of the many-orders-of-magnitude improvement in performance came as a result of engineering advances which in retrospect seem completely straightforward, and sometimes even trivial. Let us list the more important ones: variable-pitch airscrews; slots and flaps; retractable undercarriages; concrete runways; streamlining; supercharging.

"Not very spectacular, are they? Yet these things, together with steady improvements in materials and design, lifted much of the commerce of mankind into the air. For they had a synergistic effect on performance; their cumulative effect was much greater than could have been predicted by considering them individually. They did not merely add; they multiplied.

"All this took about forty years; and then there was the second technological breakthrough--the advent of the jet engine--and a new cycle of development started.

"Unless the record of the past is wholly misleading, we are going to see much of the same sequence of events in space. As far as can be judged at the moment, the equivalent items on the table of aerospace progress may be: refueling in orbit; air-breathing boosters; reusable boosters; refueling on (or from) the Moon; lightweight materials (e.g., composites and fibers). **ALSO**:

In addition to making launches of expendable satellite launch vehicles much simpler, easier, and cheaper (all ground-based rocket range and tracking infrastructure can be dispensed with as well), air-launching will also make fully-reusable space planes practical. (Designs that were developed for launch from existing large jet transports would be feasible, and the larger Stratolaunch plane will make even larger space planes practical.) Plus:

The existing space plane designs could be launched--with much longer drop zone "loiter times" if necessary--from the Stratolaunch aircraft. As well, just as is the case with the Pegasus vehicle and its L-1011 launch aircraft, expendable and reusable air-launched vehicles can be flown to the satellite owners' manufacturing facility (or facilities) aboard the Stratolaunch aircraft, which will greatly simplify the payload integration and mission logistics, and will reduce the launch costs. In addition:

While its design was dropped in 2015 in favor of a single-launch and multiple-launch (of up to three vehicles in one flight) Pegasus XL launching configuration, the development of the larger, heavier-payload Pegasus II (see: www.google.com/#q=pegasus+ii+launch+vehicle ) launch vehicle could be resumed and completed in order to provide a greater air-launched payload-to-orbit capability than the Pegasus XL's. (Air-launched reusable space planes, being "aircraft-assisted SSTO [Single-Stage-To-Orbit] spacecraft," would have smaller payloads to orbit than multi-stage expendable air-launched rockets of comparable size and mass.) The Pegasus II's larger-diameter, solid propellant first and second stage motors (they're the same diameter as the SLS/Shuttle solid boosters, while the restart-able third stage has two LOX/LH2 engines) and its 5 meter diameter payload fairing would accommodate larger spacecraft than the Pegasus XL can carry.
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  #16  
Old 06-10-2017, 08:47 AM
Jerry Irvine's Avatar
Jerry Irvine Jerry Irvine is offline
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15 years ago when White Knight 1 was built and WK2 was started, air launch was the only nearly or partially reusable option. Its lack of use due to a stubborn policy of internal propulsion development and continuous failure eliminated that 15+ year (8-02 to now 6-17) head start with immediate revenue opportunities that were also lost. The time value of revenue cannot be overstated. That's my main problem with Tripoli too.

Now we have SpaceX and Blue Origin successfully launching landable and reusable rockets.

The era of air launch is now relegated to small payloads that need unique orbits.

For the majority of mass lift SpaceX and Blue Origin will be the thing. SLS is a FEDGOV/NASA Boondoggle to keep Shuttle vendors working and nothing more.

IN the next 5 years or so I will be able to buy WK1 and WK2 in BK sale. Maybe CIA will also sell me their Proteus aircraft.

cite:

https://en.wikipedia.org/wiki/Scaled_Composites_Proteus

Last edited by Jerry Irvine : 06-10-2017 at 09:04 AM.
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  #17  
Old 06-10-2017, 09:27 AM
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Quote:
Originally Posted by Jerry Irvine
15 years ago when White Knight 1 was built and WK2 was started, air launch was the only nearly or partially reusable option. Its lack of use due to a stubborn policy of internal propulsion development and continuous failure eliminated that 15+ year (8-02 to now 6-17) head start with immediate revenue opportunities that were also lost. The time value of revenue cannot be overstated. That's my main problem with Tripoli too.

Now we have SpaceX and Blue Origin successfully launching landable and reusable rockets.

The era of air launch is now relegated to small payloads that need unique orbits.

For the majority of mass lift SpaceX and Blue Origin will be the thing. SLS is a FEDGOV/NASA Boondoggle to keep Shuttle vendors working and nothing more.

IN the next 5 years or so I will be able to buy WK1 and WK2 in BK sale. Maybe CIA will also sell me their Proteus aircraft.

cite:

https://en.wikipedia.org/wiki/Scaled_Composites_Proteus
I don't think air-launching will put SpaceX and Blue Origin out of business, but I do think it will find and enlarge a niche. Small spacecraft are now much more capable than they used to be (this is a growing trend), and the ability to avoid having to launch from a land range (which limits the launch rates) will be an attractive advantage of air-launching.
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http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
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  #18  
Old 06-10-2017, 05:27 PM
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Quote:
Originally Posted by Jerry Irvine
15 years ago when White Knight 1 was built and WK2 was started, air launch was the only nearly or partially reusable option. Its lack of use due to a stubborn policy of internal propulsion development and continuous failure eliminated that 15+ year (8-02 to now 6-17) head start with immediate revenue opportunities that were also lost. The time value of revenue cannot be overstated. That's my main problem with Tripoli too.

Now we have SpaceX and Blue Origin successfully launching landable and reusable rockets.

The era of air launch is now relegated to small payloads that need unique orbits.

For the majority of mass lift SpaceX and Blue Origin will be the thing. SLS is a FEDGOV/NASA Boondoggle to keep Shuttle vendors working and nothing more.

IN the next 5 years or so I will be able to buy WK1 and WK2 in BK sale. Maybe CIA will also sell me their Proteus aircraft.

cite:

https://en.wikipedia.org/wiki/Scaled_Composites_Proteus


Agree... Wings and mother aircraft just add more complexity and expense to an already complicated and expensive operation, is space launch... The shuttle basically proceed that already... It was a 100 ton reusable payload fairing for a 20 ton payload that required HLV power levels and expense to achieve LEO; the only real "advantage" it had was it could carry 7 astronauts at the same time, though since it was deliberately designed so it COULDN'T operate without their presence, it could be argued it was about as much of a liability...

For strictly payload to orbit capability, no wings reusable will beat winged reusable every time hands down... But launch isn't a one size fits all proposition... I could see where a stratolaunch type craft could have certain advantages, but I took it'll always be more for certain niches than the mainstem...

Wings and runway landing capability has a very high price that comes directly out of available payload capability... I could see it for a reusable rapid launch crew taxi type vehicle, for payload unless it's small and light and your launching a million of them, I don't see it...

As for shuttle SRB size solid launchers, they've been proposing that sorta thing since the 80's with no real traction... No need, expensive, unbelievably heavy, and just SO much easier and cheaper ways to do it... Then you want to add air launch and wings in just for kicks... Wouldn't sell me on it without some REALLY compelling reasons, it'd have to be sheeting that just didn't make much sense to launch any other way, and I don't know of any payloads needing a rocket that size that would make sense... Even dream chaser plans to launch on a conventional rocket...

Later! OL J R
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  #19  
Old 06-10-2017, 06:12 PM
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Dream Chaser is properly named.
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  #20  
Old 06-10-2017, 06:56 PM
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It might be just chasing a dream, but this pic is pretty cool, historically speaking.

https://www.nasa.gov/sites/default/...17-0016-016.jpg
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