Air launch capability

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p> Propforce. I confirmed that the Shuttle Max Q is around 400 lb per [sic] ft squared. Thanks for catching my error. i must learn not to trust my memory. <p><hr /></p></p></blockquote><br /><br />Thanks SG. Actually you did not make any error at all, you've confirmed the number is the same that was quoted from your memory. <br /><br />It is interesting, however; the 400 psf number is significantly different from the plot I posted which came from the aeroweb.org site. <br /> <div class="Discussion_UserSignature"> </div>

 

[bdewoody]

Wasn't one of the original shuttle concepts a mother ship/dropship configuration? It seems like I read that it was the preferred way to go by the engineers but was too costly in the short haul even though spread over 100 launches or more it would have been cheaper. <div class="Discussion_UserSignature"> <em><font size="2">Bob DeWoody</font></em> </div>

 

[bdewoody]

That's what I thought I was saying. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <em><font size="2">Bob DeWoody</font></em> </div>

 

[jpowell]

For the smaller air launch vehicles the drop in the dymanic pressure is the number one benefit. <br /><br />We have a small air launched rocket with a epoxie/paper airframe. When launched from 25,000 feet or above it does mach 3 just fine. When launched from the ground turns into potato chips at about 10,000 feet.<br /><br />By air launching, this one goes from balloon, I can elimiate 80% of the airframe weight. It gives the smaller rocket the performance of a much bigger one.<br /><br />JP<br /><br />John Powell<br />JP Aerospace, America's OTHER Space Program<br />www.jpaerospace.com

 

[PistolPete]

<blockquote><font class="small">In reply to:</font><hr /><p>We have a small air launched rocket with a epoxie/paper airframe.<p><hr /></p></p></blockquote><br /><b>EPOXY/PAPER!</b> Wow! I didn't think that notebook paper and Elmers glue could be strong enough to be an SRM casing. <img src="/images/icons/wink.gif" /><br /><br />Keep up the work, you guys are doing some cool stuff. <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>

 

[barrykirk]

Well, did you ever see one of those ESTES brand model rocket motors?<br /><br />It's nothing more than solid rocket fuel encased in a cardboard tube. <br /><br />But, I think the Paper/Epoxy was referring to the airframe not the SR itself.

 

[propforce]

<font color="yellow">"Paper-epoxy" can be a pretty sound material. </font><br /><br />Otherwise known as "carbon-carbon composite" !! <div class="Discussion_UserSignature"> </div>

 

[blink_182]

isa doggy

 

[jpowell]

We don't use any carbon-carbon.<br /><br />It really is pulp based paper, epoxied, baked and machined to shape.<br /><br />We do use conventional carbon in our larger rockets.<br /><br />JP<br />www.jpaerospace.com

 

[holmec]

In order to modify a jet liner to carry a rocket that sends people to orbit, you need to make a lot of room under the fuselage for an air launch by droping, or put some wings on the rocket for a over the top launch (like Shuttle Enterprise on the air flight tests of the Shuttle).<br /><br />If you really want to do it right, I suggest a flying wing configuration with a tail for the mothership for a drop launch and make the mothership unmanned. That way the pilot in the rocket could fly it or some guy on the ground could remotely fly it saving on weight and consequently fuel. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[halman]

holmec,<br /><br />Because the flying wing concept has never been very popular, most designs have favored more conventional arrangements. But a flying wing is able to produce a great deal of lift with a minimal amount of drag, and there is no tail section to get in the way of firing the orbiter engines before seperation, allowing a few seconds to test before commiting to a launch. But if the orbiter has a thrust ratio of greater than 1 to 1, it could fly off of the wing, if the wing were to pitch up just before seperation, and then pitch back down at seperation.<br /><br />A horizontal launch system which does not incorporate a catupult is missing out on a substantial savings, as the energy needed to accelerate the combined carrier/orbiter package to take off speeds is considerable. Also, turbo fan engines are very inefficient at low speeds, which would result in very long take-off rolls. Having the orbiter under the wing when launching from a catapult introduces complexity to the wing design, by requiring that the landing gear by much lower than the rest of the wing.<br /><br />Even if a deadstick abort to luanch site is required, the orbiter can still be flown off of the wing by the combined vehicle going into a dive, and seperating the orbiter from the wing. The wing would have to dive steeply, and circle until the orbiter has landed, but, without the orbiter weight, the wing should be able to maneuver easily, as well as glide efficiently. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[scottb50]

I would think it would be easier to push the upper stage away mechanically before igniting it's engines. Simple springs would do the trick. As I remember Enterprise was relaesed mechanically and the carrier plane reduced power and descended out of the way.<br /><br />I'm thinking more along the lines of a vertically launched flying wing with an upper stage attached to the top surface. In an emergency the upper stage could ignite and power away as a safety factor. At the top of the ascent the upper stage detaches and ignites flying a descending path to gain speed and enter a minimal orbit then relighting to achieve a higher orbit.<br /> <div class="Discussion_UserSignature"> </div>

 

[jpowell]

I've posted a video of the paper rocket launching.<br /><br />http://www.jpaerospace.com/whatsnew.html<br /><br />It has 7,400 N/S total impulse burning in four seconds.<br />It's total weight at launch was 17 pound.<br />It REALLY moves....<br /><br />JP

 

[scottb50]

The separation from the ET of the Shuttle Vehicle would be a better example. Either way I don't see it being a major problem. With a veritcally launched first stage the separation would be above a point wings would matter, just like with Shuttle. <div class="Discussion_UserSignature"> </div>

 

[mikeemmert]

Ooops! <img src="/images/icons/blush.gif" /> I posted a picture 795 pixels wide! I copy/pasted the post and have submitted a new photo. Sorry about that.

 

[mikeemmert]

I saw this post on the Boeing Blended Wing-Body in, of all places, Free Space. And here's the Wikipedia article on the X-48B. <br /><br />The image (if it posts) depicts this thing as an airliner with about an 800 passenger capacity. Browsing some of the sites indicates that there is a problem here: the wing-body tries to inflate into a sphere. But if this was unpressurized, this is not a problem. Thus the BWB has been mentioned as an airfreighter. <br /><br />I think it would make a great launch plane.<br /><br />In reply to:<br />--------------------------------------------------------------------------------<br /><br />With a veritcally launched first stage the separation would be above a point wings would matter, just like with Shuttle.<br /><br /><br /><br />--------------------------------------------------------------------------------<br /><br />With this particular plane, it would provide the zoom climb at subsonic speed with possibly the 2nd stage augementing thrust. This would provide the elevation for the 2nd stage. Any wings on upper stages of such a vehicle would be strictly for landing and might even be folded up for launch. Maybe helicopter/gyrocopter wings? I have seen such devices mentioned. <br /><br />I think rockets have been taken about as far as they can go. We need a new type of stage and I think ramjets, with liquid oxygen to augment very high altitude air, might be the ticket to a new type of booster. Ramjets are helpless, however, below mach 0.85 and need to be launched from another airplane. Such an engine would need a very large air inlet for high altitude operation, like 6 or 8 meters or so for a relatively small 90-160 tonne vehicle. That would have good operation between 10 and 30 km altitude. <br />

 

[halman]

mikeemmert,<br /><br />If we can get the orbiter/second stage to 50,000 feet before it has to start its engines, we will have accomplished the primary goal of the first stage. That altitude can be reached with regular turbofans, although it will probably take a lot of them. If we try to go higher than that, we begin requiring a second set of powerplants. Even if our carrier aircraft could acheive Mach 2 or 3, that is not a substantial portion of orbital velocity. And any altitude over 50,000 feet is going to be pretty much the same as far as a rocket propelled vehicle is concerned. As long as it has a thrust to weight ratio high enough to allow acceleration of at least 3 gravities, the orbiter can climb fast enough to avoid burning up while it reaches orbital velocity.<br /><br />So the benefits of building a complex carrier aircraft that could take the orbiter to 100,000 feet at Mach 3 are minimal in comparision to building a simple carrier aircraft that can haul a million pounds to 50,000 feet. I keep thinking of the B-17, which was considered by many (when it was the Model 299) to be 'too big' for a pilot to handle. Compare that aircraft with the 747, and then imagine a vehicle that would be to the 747 what the 747 was to the B-17. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[gunsandrockets]

"So the benefits of building a complex carrier aircraft that could take the orbiter to 100,000 feet at Mach 3 are minimal in comparision to building a simple carrier aircraft that can haul a million pounds to 50,000 feet."<br /><br />And an even smaller launch aircraft could be used if it didn't have to take-off when hauling the full weight of the rocket (or full weight of the launch aircraft). <br /><br />I like the idea of using an existing cargo plane such as the C-17 to tow a rocket-glider up to a 30,000 ft launch. The tow aircraft could take-off with minimum fuel thereby increasing it's lift capacity enormously. The rocket-glider would take-off without oxidizer minimizing it's weight on takeoff. Once the duo reached cruising altitude first the tow plane and then the glider would take on full propellant via aerial refuelling techniques.<br /><br />If the rocket-glider carried a lightweight high ISP performance rocket stage such as some variation of the Centaur, then the rocket-glider would only need suborbital performance and avoid the most difficult thermal protection issues.<br /><br />The beauty of such a three stage (five if you count the refuelling tankers) system is no cutting edge technology is needed. And much of the expensive infrastructure is off the shelf, such as the C-17, the tankers and the RL-10 engine.

 

[john_316]

Thats interesting...<br /><br /><br />I have rumours that the SR-71 actually flew at 105,000 feet on various occassions. Then again that might have been the A-12 variant but I can recall someplace reading that 105,000 feet was an altitude that the SR-71 was designed to obtain.<br /><br />Of course I may be wrong...<br /><br /><br /><img src="/images/icons/smile.gif" /><br />

 

[mikeemmert]

Although the BWB does not exist yet, the X-48B does. I think the trick to airlaunch is the second stage, and by the time that's ready the BWB will be too.<br /><br />I don't think a mach 3 launcher is worth the development costs. When you go over mach 0.85, you enter a whole different realm of design. There is plenty of equipment that can do mach 0.85 @ 35,000 feet. What's needed is to fill the gap between mach 0.85 and about mach 12, while taking as much advantage as possible of the oxygen of the surrounding air.<br /><br />It sounds like you're thinking of a short term project, and there's nothing wrong with that, but we need to replace the Space Shuttle with something better eventually.<br /><br />Turbofans provide operational flexibility. They could ferry second stages or assembled orbiters around, and also the launch point can be chosen to make second stage recovery easy. It's a problem with the SRB's; they land out in the middle of the ocean and then you have to fold the parachute. Just because the problem was solved doesn't mean it's not excessively difficult. I'm surprised we haven't lost SRB's. Parachutes are dangerous, ask any Airborne infantryman. Jimi Hendrix spent two years in the hospital because of a parachute.

 

[rocketman5000]

Parachutes are only as dangerous as the person that packed them. I skydive and don't think twice about getting out of the plane. The low number of fatalities in the sport is a testiment to attention to detail. A larger number of deaths in the community is to people not getting out of the plane in time. (crashes on take off) in fact on the plane ride up you can hear a collective sigh of relief when you get high enough to be able to actually pull your parachute and make a safe jump (about 1500 feet given correct adequate airspeed)

 

[mikeemmert]

"On September 2, 1944,(George H.W.<font color="yellow"> Bush<font color="white">, Sr.<font color="yellow"> piloted one of four Grumman TBM Avenger aircraft from VT-51 that attacked the Japanese installations on Chichi Jima. For this mission his crew included Radioman Second Class John Delaney and Lieutenant Junior Grade William White, who substituted for Bush's regular gunner. During their attack, four TBM Avengers from VT-51 encountered intense antiaircraft fire. While starting the attack, Bush's aircraft was hit and his engine caught on fire. Despite the fact that his plane was on fire, he completed his attack and released the bombs over his target, scoring several damaging hits. With his engine on fire, Bush flew several miles from the island, where he and one other crew member on the TBM Avenger bailed out of the aircraft. However, the other man's parachute did not open, and he fell to his death. It was never determined which man bailed out with Bush<font color="white">".<br /><br />(Let the record show that I do not question the courage of George H.W. Bush, Sr.)<br /><br />Well, OK, I will acknowlege that a properly packed and inspected parachute is not all that dangerous. But it must be properly packed by skilled workers. Since I don't know all that much about parachutes, rocketman5000, maybe you could tell me how much it would cost to fold and pack the parachute of an SRB or a Kliper or anything you may know about that's comparable. It just seems to me to be highly labor intensive, and highly skilled labor, too. Would it be possible that it's cheaper to use a new one every time? I do not know the answers to these questions (no one man can know everything). Thank you for your cooperation.<br /><br />I'm actually interested in anything you may be able to shed light on. After all, a parachute uses the TPS of the ship and so the cost of the thermal protection system is much less. I do know that t</font></font></font></font>

 

[scottb50]

I still think it would be easier to use the basic Shuttle architecture as a flyback booster carrying a second stage to 80 miles and releasing it at mach 15. <br /><br />To get a meaningful payload into orbit pretty much rules out a turbofan of turbojet powered vehicle. Look at Pegasaus, it takes an L-1011 to get a rocket to release altitude with a little more than a thousand pound payload.<br /><br />What I think would work would be a vertically launched first stage with SSME's and fixed SRB's. Fly it back, refuel it and attach another second stage. <div class="Discussion_UserSignature"> </div>

 

[nyarlathotep]

>"Look at Pegasaus, it takes an L-1011 to get a rocket to release altitude with a little more than a thousand pound payload. "<br /><br />Orbital Sciences could have used a smaller plane. The L-1011 was just a whole lot cheaper to purchase, modify and service.

 

[mikeemmert]

Well, Scottb50, rockets are so ... (?**@#...?) ... <i>archaeological</i>. There's all that free air sitting around, just loaded with oxygen.<br /><br />But, of course, it's not concentrated enough at high altitude. The problem with most of the air breathing boosters such as X-43 is that they are practicing a purist approach.<br /><br />There seems to have been little research into putting additional oxygen into inlet air. There was the MIPSS system (they need to shoot that name or something) but the last website I read on that emphatically emphasised that this was a bolt on system for existing jet fighters. Such a device would be it's own system, not a compromise.<br /><br />Amongst the advantages are that above mach 5, oxygen/nitrogen air molecules break up, then recombine to form nitric oxide. This does not release energy, it absorbs it. Chemical TPS, if you will - or an antifire-ball. That energy is released by combustion, so it's not lost.<br /><br />Rockets, frustratingly, have an ISP just short of requirements. If you start calculating ISP of an oxygen augmented ramjet, you see it drop from a highly satisfying 3000 seconds down to about 600 seconds and then <i>tend to forget that 600 seconds of ISP is a great number!</i>. Remember, all this stuff is exponential, so a small improvement gives large benefits.<br /><br />Anyway, when you reach really high altitudes, you have to go to a rocket or maybe a rotovator. Still, I think the Rube Goldberglike contraption should be able to get to the mach 15 you mentioned easily.