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Thread: Beyond the SR-71

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    Moderator Topaz's Avatar
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    Re: Beyond the SR-71

    Quote Originally Posted by DangerZone View Post
    The X-37 has a payload of more than half a ton, would that not be enough to carry the system up into space to a certain station? Even if the system would be too heavy in one piece, it could be transported with the X-37 in modules/parts and then assembled in space. People sometimes watch the maritime LAWS system which has to be heavy and sturdy to resist high waves. Aircraft laser weapon systems built by Raytheon, Northop Gruman and other manufacturers are lighter. The X-37 had multiple missions so there could be more than one laser system in space left to operate as independent satellite so far.
    The X-37 flies in a much different orbit than the ISS. And if the USAF was flying it there, Russia would be complicit in keeping the flights secret. Not only are they full partners on the ISS, but they have their own orbital tracking system. If there was "another station", then we'd know about that, too. A spacecraft has to be really small to fly in orbit above the Earth without being detected.

    Additionally, why bother flying the X-37 to the ISS "secretly" when there are already Progress, Dragon, Cygnus, H-2, and ATV transports that go there all the time?


    Quote Originally Posted by DangerZone View Post
    Isn't the service ceiling of the RQ-180 around 60 000 feet? Since it's max speed is subsonic, it could be intercepted even by an old MiG-21....
    I don't know the operational altitude of the RQ-180 and neither do you. Wikipedia lists 60k MSL, sure, but that's like the SR-71 was said to fly "60,000' and Mach 3, 'plus'". Regardless, the RQ-180 is orders of magnitude more stealthy than the SR-71, and probably quite a bit more stealthy than even the B-2, so the question isn't "Can they intercept it?". The question is, "Do they even know it's there?". The answer to that is, "Probably not."
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    Registered User Wanttaja's Avatar
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    Re: Beyond the SR-71

    Quote Originally Posted by Swampyankee View Post
    I don't know the orbital parameters of the spy satellites; they're not exactly publicized....
    Not by the owners, no. But there's a whole group of hobbyists that track the things and post the orbital elements.

    Quote Originally Posted by Swampyankee View Post
    ... but I believe the optical ones aren't in geosynchronous orbit.
    It's like taking pictures of a baseball game. Shoot an image way up in the stands, you need a nice camera with a big lens. Stand next to the home plate umpire, and you can get by with your lil' ol' Brownie.

    So lower is better, limited by your drag makeup capability and your tolerance to atomic oxygen. SPOT would be a good example... a commercial French imaging satellite, altitude of about 500 miles.

    Orbit inclination depends on the type of camera and what the mission is. If you're taking visible-light pictures, you'd like to fly over when the sun is illuminating the target. However, your analysts are going to want consistent lighting...it's harder to tell changes (especially in height) if the shadows point in different directions on every shot.

    So most visible-light system operate in Sun Synchronous orbits. The inclination of these varies with the orbit altitude, but they're usually around 95-105 degrees. These are arranged so that the orbital plane's angle to the sun stays constant; this means it flies over a target at roughly the same time of day, each time. How often it can do that for a particular target depends on other factors in the orbit. Of course, half the passes are nighttime ones.

    Ron Wanttaja

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    Re: Beyond the SR-71

    I'll bet that Ron could, but will not, tell us what the X-37 is used for.


    BJC

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    Re: Beyond the SR-71

    Do they have insect sized spy drones yet?

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    Re: Beyond the SR-71

    Quote Originally Posted by Wanttaja View Post
    So most visible-light system operate in Sun Synchronous orbits.
    So that would be about 1,000 MPH at sea level?

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    Re: Beyond the SR-71

    Quote Originally Posted by Topaz View Post
    The X-37 flies in a much different orbit than the ISS. And if the USAF was flying it there, Russia would be complicit in keeping the flights secret. Not only are they full partners on the ISS, but they have their own orbital tracking system. If there was "another station", then we'd know about that, too. A spacecraft has to be really small to fly in orbit above the Earth without being detected.

    Additionally, why bother flying the X-37 to the ISS "secretly" when there are already Progress, Dragon, Cygnus, H-2, and ATV transports that go there all the time?
    It could be a language thing. A station or artificial satellite for me can vary from a couple kilos to a couple tons. The ISS is a pretty large structure visible to the naked eye during clear sky when it passes over. This is not something the X-37 could ever carry or install in orbit to become a satellite or stationary object. Progress is a Russian launch vehicle, I doubt they would be happy to install weapons able to destroy Chinese and Russian satellites into orbit. Plus, they have experience of launch failures. So do Dragon, Cygnus, H-2 and ATV. Any smart person would want a more reliable means to carry anti-satellite weapons into orbit. Logically, the best means to do that would be exactly the X-37. I am not saying they did that, I am saying a smart person would do that to reduce risks of losing expensive laser weapons or having information about it leaked around.

    Quote Originally Posted by Topaz View Post
    I don't know the operational altitude of the RQ-180 and neither do you. Wikipedia lists 60k MSL, sure, but that's like the SR-71 was said to fly "60,000' and Mach 3, 'plus'". Regardless, the RQ-180 is orders of magnitude more stealthy than the SR-71, and probably quite a bit more stealthy than even the B-2, so the question isn't "Can they intercept it?". The question is, "Do they even know it's there?". The answer to that is, "Probably not."
    You are right, I cannot know the exact operational altitude of the RQ-180. What I can do is use simple physics to calculate this information. I can understand the power and thrust of it's engines, determine the surface area, calculate the drag and approximate the mass. In steady flight thrust equals drag, weight equals lift. Since the RQ-180 is subsonic, I assure you that the SR-71 is a much higher (and definitely faster) cruising aircraft. Feel free to do the math yourself for any given aircraft, you'd be surprised how precise your approximations will become after doing so for a dozen. It might not be as easy as it sounds at first try and it takes time, but curiosity usually rewards those tho dare.

    Please don't get me wrong, the RQ-180 is a great aircraft. Yet it just does not seem to be the successor of the SR-71. The Blackbird is a remarkable piece of engineering, it's almost a spacecraft. The only thing that prevents it to be a spacecraft is its engines. Remember Raymer and his books that the aircraft is built around the engine and not the other way around? So please bear with me for a second and let me know what you think. With the advances of modern materials and engineering the experts understand that a turbine based engine has reached its limit with the SR-71 engines. It doesn't get any better than that. If one wants to fly faster/higher/better, a new engine should be developed. We all know that at these altitudes and speeds - ramjets and scramjets make more sense than turbines. We also know the technology IS THERE, that the future lies in improving the efficiency and reducing heat losses. Getting more work by allowing the exhaust gasses to produce more thrust and a cooler hot part, more bang for the buck. Whoever has experience with rocket, pulsejet and ramjet engines understands how this is feasible. So here's the question: what if the company building the SR-71 successor has managed to improve the engines by going for a more efficient pulsejet/ramjet engine and ditched all the compressors, turbines and limitations of the SR-71? If a hobby pilot like me could do it, I bet that a team of well paid experienced aerospace engineers working on such a project every day from 9 to 5 will do much better and more of it. And if they managed to build excellent engines, how much time do you think they'd need to wrap a great fuselage around them?

    Finally, do people know if an 'invisible' or advanced airplane is there? On a clear day, I can detect visually everything up to at least 60k feet even if it might not be visible on some radars. I'd have to use a scope for anything higher than that, and a larger telescope for satellites. The ISS is often too bright due to reflection, it looks like a very shiny star passing by vary fast. At night when the humidity is high, some 'invisible' aircraft flying by emit a static 'shade'. It looks like a slightly brighter mist in the dark, it's hard to describe. So, if I can see that much as a civilian, what do you think experienced radar and military surveilance observers could see?

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    Re: Beyond the SR-71

    Quote Originally Posted by BJC View Post
    I'll bet that Ron could, but will not, tell us what the X-37 is used for.
    "If I did, what would happen to man's search for knowledge?"
    -Cyrano Jones

    Ron "Who put the tribbles in the Quadrotriticale?" Wanttaja

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    Re: Beyond the SR-71

    Quote Originally Posted by DangerZone View Post
    It could be a language thing. ...
    Seems to me more like pretty wild speculation. I'll simply say that I disagree, and let you continue as you will. No offense intended.
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    Registered User DangerZone's Avatar
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    Re: Beyond the SR-71

    Quote Originally Posted by Topaz View Post
    Seems to me more like pretty wild speculation. I'll simply say that I disagree, and let you continue as you will. No offense intended.
    Actually, we seem to agree. At least I agree with you - you are right that what I wrote is based on pure speculation. My speculation is based on what technology allows, the capacity of engineers and common sense of decision makers. I am not saying they had to use the X-37 for the purpose of carrying small laser weapon stations into space, I simply said this is what a smart person would do if they'd have to. And in case of global conflict spread, I'd rather have a weapon and not need it up there than not have one and need it. If it becomes obsolete at any point, simply activate the small thrusters out of orbit and send them burning down into the atmosphere. You wouldn't even know they were there, just like 'invisible' airplanes which fly by unnoticed to more than 99.99% of the general population. That's why I'd rule out the X-37 as a spacecraft to inherit the SR-71 legacy.

    Thus concerning the SR-71 successor, common sense allows us to speculate (again, I agree with you this is pure speculation) that the SR-72 or whatever they'd call it - has better performance. Provided it exists, of course. At least that's what I thought this thread is about, whether we could use common sense and logic to see what the SR-71 successor would be like. If the mission requirement would be only to gather data, high definition photos and great quality videos of something on the Earth surface, then the RQ-180 would be ok for such a task. A bit expensive though, because one could design a drone able to acomplish the same mission requirements for 1 thousandth of the RQ-180 cost. Seeing the mass of the RQ-180, the surface area, the speed and engines, one would have to be blind not to see it could do much more, like carry weapons (including nuclear).

    Comparing the SR-71 and the RQ-180 shows huge differences: the first is crewed, supersonic and has no weapons while the latter is unmanned, subsonic and carries weapons. This is why I can't see the RQ-180 as the successor of the SR-71, provided there is one yet (pure speculation again). The SR-72 story in Aviation Week has some good points. Like - the speed, the mission requirements, the capabilities, the improved efficiency over the SR-71. The design and engines are most probably just an artistic impression, specially the engines. We could sum up all we know about the SR-72 specifications just by trying to speculate what it will be able to do. My opinion is that the SR-71 successor could be hypersonic, could have ramjet/scramjet/pulsedet engines without the complexity of mechanical compressors and turbines, could be based on actual research done by Lockheed Martin, DARPA and guys at Skunkworks (I love that name), could be stealthy and have engines using thrust augmentation with heat signature reduction, could be manned or crewed and could be based on recent research done on the HTV projects.

    Click image for larger version. 

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    And the media shows the SR-72 as something completely different:
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    In fact, even the DARPA dual cycle challenge with a combined turbine engine seems like a student exercise rather than search for a solution:
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    We can notice that if the turbine engines are intended just for take off and reaching the speed and altitude - rocket engines would weigh much less, be less complex and have more reliability than turbines. So, we could pretty much SPECULATE that the teams of Lockheed Martin, DARPA and Skunkworks combined found a much better solution than digging high heat turbines deep into the fuselage. Thermodinamically, it would be a nightmare to reduce its heat signature, specially with the outside surface area adding to this heat due to friction at hypersonic speed. With the usage of small rocket engines, one could even allow such aircraft to take off vertically and land conventionally, just like the Shuttle did but with much less fuel burn. The mass of the turbines, inlets, ducts and heat reducing machinery would be way more than what such an aircraft would use per vertical take off if MTOW is kept down low to a rational level. Again, this is speculation. It is only my asumption that these guys are smart and understand it would be more efficient to have lighter and less complex engines even if these use more fuel for the first 60 seconds of the flight until reaching ramjet or scramjet regimes.

    In conclusion, it seems we don't disagree because you are right that these are speculations. I just followed the title of the thread, about what would the SR-71 successor be like. It's an interesting topic, a brilliant airplane, and I am sure whoever is working on the SR-72 (or whatever it is called) will make another remarkable piece of engineering.

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    Re: Beyond the SR-71

    The following is a video of the related program X-43 from more than a decade ago, some pretty decent pics show the internals of the aircraft/spacecraft/airbody (is there any better name for it?).



    The speed is quite close to some ETO programs.

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