Air launch capability

[scipt]

I was wondering if air launch from a converted A380 or other large commercial aircraft could improve maximum altitude. Ok, you can't go as high in a plane the A380 as you can using White Knight (i think), but you can drop a larger rocket for air launch. Given no budget constraints does anyone think this would work? <div class="Discussion_UserSignature"> </div>

 

[holmec]

Well Darpa is researching launching a falcon rocket from a C-17. C17 flight altitude seems to be comparable with most commercial liners. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[halman]

scipt,<br /><br />A lot of people do. Reaching orbit is a function of going fast, not going straight up. But a surface launched rocket can not go fast until it has gone straight up for a while, to get out of the thickest part of the atmosphere. Most of the propellant load of the Space Shuttle is burned in the first two minutes, lifting the craft against gravity. Every second of vertical flight robs the vehicle of 20 miles per hour of velocity.<br /><br />There is no theoretical limit to how large a wing we could build. No one has ever had any reason to build anything bigger than the C-5 or its Russian equivalant, and both of those aircraft have been around since the 1960's. Using a catapult to accelerate the combined carrier/launcher 'stack', it is certainly possible to get 3 or 4 million pounds into the air at a velocity which would be well over stall speed, and a dozen modern turbofan engines could enable such a 'stack' to climb at 1,000 feet per minute, which is what the White Knight was capable of carrying SpaceShip One.<br /><br />Using an existing aircraft imposes a severe penalty due to the fuselage creating drag and imposing useless weight. This is why Rutan's designs for the White Knight aircraft look so strange; they are meant for lifting a payload external to the vehicle, not inside of it. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>Using an existing aircraft imposes a severe penalty due to the fuselage creating drag and imposing useless weight. This is why Rutan's designs for the White Knight aircraft look so strange; they are meant for lifting a payload external to the vehicle, not inside of it. <p><hr /></p></p></blockquote><br /><br />A very good point. There are 2 primary hurdles of using existing aircraft for air launch, they are:<br /><br />1) Existing lift, climb, and speed capability.<br /><br />2) Configuration on attaching the "upper stage" (rocket portion) and how to separate at altitude.<br /><br />Imagine the space shuttle on top of the 747. Would the shuttle get better or worse performance using 747 air launch (without the 2 SRBs) versus the existing ground launch (with the 2 SRBs)? How would one separate the shuttle from the 747 at 30K feet going at 500 mph?<br /><br />One must ask what is the benefit of using air launch vs. ground launch, and conduct a cost benefit analysis. In the case of NASA (or other government agencies) where cost is not a primary driver, then do a performance/ operational benefit analysis. <br /><br /> <div class="Discussion_UserSignature"> </div>

 

[spacefire]

The B58 Hustler had a huge fuel tank slung under the fuselage. I always wodnered if that could be replaced by a small rocket. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[qso1]

If you want to get the B-58 into space, you'd keep the tank or swap it for a bigger one and attach a rocket to whichever tank you go with, but the tank that was utilized on a B-58 probably wouldn't contain enough propellant to get the B-58 to LEO.<br /><br />Back in 1983, the AF studied a concept for air launching a small spaceplane atop a 747. The spaceplane was about the same size as an HL-20 and sat atop a propellant tank which in turn was mounted to the 747.<br /><br />For sending people into space, air launched concepts offer a lot of flexibility where launching from many locations are concerned. It also has the potential to reduce costs by eliminating the need for launch pads. The drawbacks are of course, getting a carrier plane with enough fuel and speed to allow the spaceplane to reach orbit.<br /><br />An example drawback can be found in this statement from propforce:<br /><br />Imagine the space shuttle on top of the 747. Would the shuttle get better or worse performance using 747 air launch (without the 2 SRBs) versus the existing ground launch (with the 2 SRBs)? How would one separate the shuttle from the 747 at 30K feet going at 500 mph?<br /><br />Me:<br />This question however, is easy to answer, The present orbiter cannot be launched from a 747 without additional boost. Its simply too massive. In addition to that, no mention was made of the ET. The 747 cannot carry a fully loaded ET and orbiter. Without ET/SRBs, the shuttle goes nowhere but down.<br /><br />When the Enterprise was airdropped from a 747, it was lighter because among other things. It had dummy SSMEs and no TPS.<br /><br />Air launched concepts from a 747 would have to be smaller vehicles such as the air force 1983 study. And these vehicles could be mounted on ETs although thats aerodynamically dirty if you ask me, or build a vehicle designed for airlaunch with internal tanking. The 747 would have to be extensivelly modified as well to contain the propellant replenish equipment for the spaceplane. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[scipt]

I wonder what altitude Spaceship Two could achieve if they keep the larger carrier design. Drop the number of astonauts to 3 - and use the extra space/weight for fuel. And add some small expendable SRB's to the fuselage of the spaceplane. <br /><br />160miles alt? 30 mins of weightlessness? <div class="Discussion_UserSignature"> </div>

 

[qso1]

Thats true. The 747 had to make a shallow dive as well to accomodate the release of the Enterprise/ <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[qso1]

And a higher cost which means higher ticket prices. They have to go with the optimal balance of cost and capability to ever hope to make eventual profits. This means maximize passenger capacity to the extent possible. Keep the SS-2 design as simple, safe, and robust as possible.<br /><br />However, if they are successful initially, then they could look at possibilities such as what you mentioned. Although I think they would want to keep a larger passenger capacity to hold ticket prices down.<br /><br />Without knowing the exact specs of your proposal, I cannot say exactly what altitude and micro "G" duration they would achieve. I'm not an engineer anyway but I can usually estimate fairly closely in some cases. In this case, I'd have to know more technical specs. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[spacefire]

sorry qso, I meant the B58 to be the carrier aircraft. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[edkyle98]

The cargo-hauling capacity would be more important than the drop altitude. Just getting a few miles into the sky is enough to gain one of the principal advantages of air-launch - the improved efficiency of rocket engines as they approach vacuum conditions.<br /><br />But the mass is a bigger deal in this case. An L1011 can lift more than 40 tonnes, and perhaps as much as 60 tonnes, but Pegasus XL only weighs 23 tonnes at launch. C-17 can haul 76.6 tonnes, but the AirLaunch QuickReach drop mass would be 32.65 tonnes. These numbers indicate that practical air launch drop masses are unlikely to exceed 50% of the standard cargo hauling capacity of a freight airliner.<br /><br />But that is less of a problem with A380, which can haul 150 tonnes of cargo, far more than even 747 which can handle 114 tonnes. 150 cargo tonnes means that it might be possible to drop a 75 tonne air launcher. This could be enough to handle perhaps 1.5 tonnes to low earth orbit. That's equivalent to the capacity of a Vega or a Taurus. That's enough to have handled about 25% of all of the space launch payloads flown in the world so far this year.<br /><br /> - Ed Kyle

 

[qso1]

That clears it up, thanks. Unfortunately the B-58 has long been retired and out of production. But being that it was our first supersonic bomber, it would certainly have a speed advantage over most other carrier craft. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[scottb50]

But being that it was our first supersonic bomber, it would certainly have a speed advantage over most other carrier craft....<br /><br />Not once you strapped a payload to it. <div class="Discussion_UserSignature"> </div>

 

[qso1]

Good point. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[PistolPete]

There is only one problem (and it's a big one) with launching anything large from a supersonic carrier aircraft. During the late 60s the USAF attempted to launch a D-21 reconnaissance drone from an SR-71 at Mach 3. The D-21 was long enough that its nose hit the supersonic shockwave coming off of the SR-71's nose before the D-21 could get far enough away. The D-21 bounced off the shockwave and hit the SR-71, causing the SR-71 to break up at high speeds. I don't recall if the crew survived.<br /><br />If you want to use the B-58 as a carrier aircraft, then you need it to fly a high angle flight profile that will take it above 100,000 ft. At that altitude it the air is thin enough to be safe. Unfortunatly, I doubt that the B-58 could maintain Mach 1, let alone Mach 3, in a near vertical climb past 100,000 ft., so you would loose a lot of delta v, but at least you could get a fair sized rocket above most of the atmosphere. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[qso1]

PistolPete:<br />I doubt that the B-58 could maintain Mach 1, let alone Mach 3, in a near vertical climb past...<br /><br />Me:<br />Not only that but the B-58 wasn't a mach 3 craft in level flight. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[PistolPete]

True. I confused the SR-71 and B-58 stats. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[PistolPete]

Also, I read somewhere that the SR-71 could have easily beat the MiG-25's altitude record, but it would have been a one way trip. The SR-71 wasn't designed for high angles of attack and would have gone into an uncontrollable spin upon passing 100,000 ft. I imiagine that the B-58 would have had similar problems. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>An example drawback can be found in this statement from propforce: <br /><br />Imagine the space shuttle on top of the 747. Would the shuttle get better or worse performance using 747 air launch (without the 2 SRBs) versus the existing ground launch (with the 2 SRBs)? How would one separate the shuttle from the 747 at 30K feet going at 500 mph? <br /><br />Me: <br />This question however, is easy to answer, The present orbiter cannot be launched from a 747 without additional boost. Its simply too massive. In addition to that, no mention was made of the ET. The 747 cannot carry a fully loaded ET and orbiter. Without ET/SRBs, the shuttle goes nowhere but down. <br /><br />When the Enterprise was airdropped from a 747, it was lighter because among other things. It had dummy SSMEs and no TPS. <br /><br />Air launched concepts from a 747 would have to be smaller vehicles such as the air force 1983 study. And these vehicles could be mounted on ETs although thats aerodynamically dirty if you ask me, or build a vehicle designed for airlaunch with internal tanking. The 747 would have to be extensivelly modified as well to contain the propellant replenish equipment for the spaceplane. <p><hr /></p></p></blockquote><br /><br />Agree. Which goes back to my original point that the size of upper stage depends on the configuration, lift, climb and speed capability of the carrier aircraft. My "problem statement" was meant to elucidate these issues with carrier aircraft and its impact, ultimately, on the payload capability (including humans as payload) for the rocket. <br /><br />Now taking the shuttle/ 747 as an example further, assuming a much smaller shuttle with some ET tank on top of the 747, how would you conduct a "separation" flight test? Would you fire up the SSMEs before separating from the 747, hence risk the burn-up of its tail section? Or would you "free flight" the shuttle upon the separation, then ignite the SSMEs after separati <div class="Discussion_UserSignature"> </div>

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>There is only one problem (and it's a big one) with launching anything large from a supersonic carrier aircraft. During the late 60s the USAF attempted to launch a D-21 reconnaissance drone from an SR-71 at Mach 3. The D-21 was long enough that its nose hit the supersonic shockwave coming off of the SR-71's nose before the D-21 could get far enough away. The D-21 bounced off the shockwave and hit the SR-71, causing the SR-71 to break up at high speeds. I don't recall if the crew survived.<p><hr /></p></p></blockquote><br /><br />The crew did not survive on that flight.<br /><br />The reason for the separation failure of D-21 as far as I can recall from reading, was that the D-21 being a ramjet powered system (not a rocket) failed to function properly hence lost the thrust requried. <br /> <div class="Discussion_UserSignature"> </div>

 

[PistolPete]

The Russians had a design similar to what you are talking about called MAKS. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[qso1]

And therein lies the whole problem. The cost barrier. When the AF studied the concept I mentioned back in 1983, part of the proposal was to put an SSME in the tail of the 747. But basically, we will be very hard pressed to develop any sort of winged vehicle as long as the costs are considered to be too high. And anything to do with human space flight is considered too high by a lot of folks. Of course, the AF abandoned their concept but I don't recall the exact reasons that they did. It may have proven unworkable even on paper.<br /><br />When NASA started the VSE program to go back to the moon. The proposed crew transport vehicle was something called OSP marketed at one point as "Safe, simple, soon". A sort of little winged or lifting body, forget which...but it wasn't a capsule. But as winged or lifters go, it was probably the simplest when compared to other concepts such as air launched or SSTO. Cost of capsule is lower than cost of a winged or lifting body so the capsule was adapted. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>"...The crew did not survive on that flight...." <br /><br />Both ejected safely, but only one was rescued. The other crew member drowned. <p><hr /></p></p></blockquote><br /><br />Thanks Newzie, I know I can count on you to set my fact straight <img src="/images/icons/smile.gif" />.<br /><br />BTW, I've just noticed that you're a member of "mission control team". Congratulation ! <img src="/images/icons/cool.gif" /><br /> <div class="Discussion_UserSignature"> </div>

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>And therein lies the whole problem. The cost barrier. When the AF studied the concept I mentioned back in 1983, part of the proposal was to put an SSME in the tail of the 747. But basically, we will be very hard pressed to develop any sort of winged vehicle as long as the costs are considered to be too high.<p><hr /></p></p></blockquote><br /><br />Lots of modification would've been necessary on the 747 as one moves away from powerpoint charts into detail design. The 747 airframe is not designed to handle supersonic flight nor with high g-force acceleration and climb. <br /><br />I had a rude awakening a few years back when we were looking at a similar concept. GE the manufacturer of turbofan engine, the GE90, wanted a minimal of $1 billion dollars for slightest modification on the GE90 <img src="/images/icons/shocked.gif" />...<br /><br />... and I'd thought ground launch rocket is expensive !! <br /> <div class="Discussion_UserSignature"> </div>

 

[propforce]

<br /><font color="yellow">The Russians had a design similar to what you are talking about called MAKS. </font><br /> <br />Thanks for the link. <img src="/images/icons/smile.gif" /><br /> <div class="Discussion_UserSignature"> </div>