Piczookery: Transatmospheric launch vehicle January 19, 2007 Posted by Murdoc An artist’s concept of a transatmospheric vehicle and its auxiliary fuel tanks on the back of Boeing 747 aircraft. Photo courtesy of Boeing Co. Camera Operator: BOEING CO. Date Shot: 9 Jan 1985 Found while looking for something else at DVIC. Updated: January 19, 2007 at 7:59 am ◀ Couldn’t happen to a nicer militia Piczookery: Backwards Flags ▶ Comments Shouldn’t the tail be a split double tail? Cool picture. Thanks for sharing it, Murdoc. One of these days I’m going to do a math model of the Saturn V launch profile. It recently occured to me that all of the fuel used by that rocket to go vertical is essentially wasted. As I mentioned earlier, if you do the math, the energy required to get a satellite to orbit (E=mgh) is negligible compared to the energy required to get it up to orbital velocity (E=1/2mv^2). So the 1/10th of the fuel load the Saturn spent clearing the launch tower was essentially all wasted. Until the rocket is flying completely parallel to the ground, it is wasting some portion of the thrust generated by the rocket engines simply to produce lift. It would be interesting to calculate how much of the fuel of a vertical take off rocket is wasted that way and see how that would compare to the mass of lift producing wings for a horizontal take off vehicle. I suppose someone has already done that trade. Even better still would be finding a paper where someone has calculated all this for me. Shipmates, Personally, I’m interested in how they start the main engines on the parasite without burning the tail off of the 747….. Considering the weight of the vehicle and it’s aux fuel tank, how can it possibly generate enough lift to clear the 747, and then start it’s main engines before reaching stall speed? What’s the emergency perameters for a failed start of the main engines? Got an ejection system, or do you just eject the aux fule tank and hope for the best? Enquiring minds want to know 🙂 Respects, I don’t post enough about space stuff. I’m certainly no expert on the subject, but I’ve been a space fan even longer than a military fan. (I’ve pretty much stopped blogging much about sports, since I’m not really that much of an athletic supporter.) Defens: You’re welcome. I posted it largely for your benefit. I would have gladly stuck with Saturn Vs and other conventional rockets and used the Space Shuttle as an auxiliary/experimental effort rather than dumping our entire space program into it. A gazillion dollars into the Shuttle program as a developmental effort that would lead to the ‘next big thing’ while keeping the main space effort running with existing technology would have been much more satisfying than dropping existing technology and pouring two gazillion dollars into the Shuttle and attached programs. If the Saturn/Apollo programs had been kept going we could have been to Mars long ago if we had decided it was worth it. Now, we need to reinvent Apollo just to get back to the moon. And that’s going to make the decision that it’s worth it a tough one to stick to. Meanwhile, reusable space transportation isn’t really any farther than it was in 1975 or so. And ‘other means’ have basically been abandoned by NASA. The advantage is that space elevators, which I believe are the ‘next big thing’ for many space access needs, are in the hands of private enterprise. That gives them a fighting chance to succeed. C-Low and Tim: While I have no info on the program or proposal this image is for, I must agree that the vehicle and tank look even less lifting than the Shuttle. Even the 747 Shuttle Carrier Aircraft have extra vertical stabilizers added to the horizontal stabilizers, and this thing would be a far heavier and problematic load. (Also, look what happened to the jet at the beginning of ‘Moonraker’ when someone fired the shuttle’s engines while it was mounted on the transport plane. Not good.) My guess would be that this is merely a piece of concept art meant to get the general idea across rather than a real representation of a serious design. Incidentally, I just posted an early pic of the first 747 SCA (still in its American Airlines colors) in my post on ‘backwards’ flags: http://www.murdoconline.net/archives/004480.html I’m not familiar with the work behind the concept vehicle Murdoc posted the image of, but it could be that the 747 is supposed to drop out from underneath doing a slightly negative g maneuver (not fun). Or this could just be a ferrying concept, but I don’t know why they’d have that observation station on top for that mission. If the 747 were to drop out from under the orbital vehicle and tank, it would probably do so while aligned with the runway. That way if the motors didn’t light, the orbiter would drop the tank (hopefully somewhere not populated) and do a dead stick landing like the shuttle does now. Personally I prefer the idea of a belly drop like Rutan uses. That way you have gravity working with you and the lightened mother ship will have a natural tendency to rise away from the second stage. The down side is some long landing gear, or maybe some gull wings like the Corsair. Space exploration was the reason I became an engineer. I couldn’t believe my first job was working with the shuttle program. Later I would learn to be very disappointed. I was stupid enough to think space station would be better, but learned that hard lesson too. This stuff bothered me a lot more before I knew the rules of the game. Now that I know how the system works, I can game it to do a little good every now and then. It’s a long way from what I hoped for, but better than nothing and it pays the bills. I just happened to remember where I’d seen that maneuver before. DFENS, Yeah, it worked great for the gliding tests. Remember also, thoigh, that there was no power to the main engines, and the pilots both had ejection seats….. just in case:) The SR-71 program also tried a parasite launch vehicle. It was built around the main engine from the SR-71, with similar wings and a fin. There was a LOT of trouble with it launching (including engine start-ups) at high speed, and the program was eventually abandoned. There may also ahve been an SR-71 lost as a result of an accident with this program as well, but I can’t remember off the top of my head. It sucks getting older and taking drugs….. sigh ….. Respects, What I was saying is that most likely the vehicle in the picture would have launched with the engines cold too. If they didn’t light, the orbiter would have dropped the tank and dead stick landed like the Enterprise did in the video. The SR-71 drone is a different case. At that speed, had it launched with the engine off they likely would have never been able to light the ramjet. It would have lost too much speed too quickly. From what I understand from having worked on high speed vehicles, when an engine unstarts it feels like someone hit it on the nose with a giant hammer, it slows down that fast. Defens,i do remember seeing a concept winged Saturn flyback stage in O’Neil book.. I don’t have a very high opinion of winged upper stages. The mass of the wings is dead weight during launch, on orbit, and reentry through the upper atmosphere. In fact, during reentry they are a considerable liability because they increase the area exposed to atmospheric heating by an order of magnitude compared to the base area of a capsule. As we saw recently with Columbia, this increase in area increases vulnerability to burn through. The only time the wings are useful is during the final stage of reentry, and then a parachute or some other deployable lift device would serve the same function for less weight. NASA’s shuttle-c concept which replaces the orbiter with a cargo container more than doubles the lift capability of the shuttle. To be fair, the shuttle-c gets rid of the astronauts and all their associated life support equipment too, so the cargo capacity increase is not purely whacking off the wings. The shuttle-c is what NASA should have gone with to go back to the Moon instead of their currently planned heavy lift vehicle. Here’s another look back in space history.