Superfast military plane hit Mach 20 before crash
msnbc.msn.com
msnbc.msn.com
http://en.wikipedia.org/wiki/Non-rocket_spacelaunch#Hyperson...
http://www.enotes.com/topic/Tether_propulsion#HASTOL_.E2.80....
This puts the tensile strength necessary into the realm of existing high-strength polymer cables.
If we could build a robust fully-reusable space plane that can go Mach 15, and we could also find a way to rendezvous it with a rotating tether, we could free ourselves from the nastiness of the rocket equation and achieve inexpensive space access.
A better example might be fancy chemicals. Rather than purchasing a "very expensive machine" to ensure a specific environment for reaction, it might be cheaper to send the materials to zero g for processing. I'm not a chemist, but watching astronauts play with bubbles and flames in space makes me think you could get a lot of precision by modeling everything as perfect spheres. So, the reactions are simper to model, easier to get accurate and precise outcomes.
Delivery of all goods is simply a drop shipment.
What I'm proposing isn't made of unobtanium. Spectra has the required tensile strength.
If we could build a robust fully-reusable space plane that can go Mach 15 free from the nastiness of the rocket equation then we already practically achieved inexpensive space access :). If you look at the rocket equation - it is the first 15 Mach that require to burn almost all this mass of fuel through all these big engines pumped from all these big tanks. Once you're going 15 Mach - to get to the 30 Mach for the payload of N kg, you'd need to burn only ~N kg of LH2+LOX (4.5km/s nozzle speed) - so not much gain would come by replacing rocket propulsion with anything else on the second half of the acceleration. The first half is the problem.
By not requiring full orbital velocity, we are freeing ourselves from the particular nastiness of the rocket equation on the surface of our planet. Our gravity well is just deep enough, that SSTO is just beyond the edge of what we can achieve with chemical rockets. I proposed Mach 15 because it's significantly less than the Mach 20 result, but in this case it's clear that I still chose a number too high.
An air breathing craft that can get to Mach 10+ would easily drop the cost of getting to space to 1/10th what it is today and let do things like have some reserve fuel in case you messed up the landing and want to come around for another pass. If you can hit Mach 20 then LEO starts to take less energy than flying around the world.
there are 2 issues with oxygen from the air:
1. the air is moving fast relatively to the aircraft frame of reference. To burn it, the air should be slowed down in the aircraft frame of reference. That means acceleration of that air in the Earth frame of reference. It isn't a noticeable energy loss below Mach 2, yet above the Mach 2-3 it starts to impact the efficiency of the air breathing scheme to the point that rocket engine carrying oxygen with it (ie. accelerating it in the Earth frame of reference and keeping it non-moving in the aircraft frame of reference) doesn't look that less efficient, and the higher the speed the less the efficiency gap. Scramjets (no slowing down of the air) while seemingly fixing that problem face the other side of the same issue - trying to impact even small amount of additional momentum on the already fast moving air (in the aircraft frame of reference) requires an unproportionally increasing (the same v square) amount of power.
2. due to composition of the Earth atmosphere, to burn 1kg of oxygen, the aircraft need to pump through engine - ie. accelerate as described in the point 1. above to the speed close to its own in the Earth's frame of reference - 5 kg of air.
The jet propulsion itself doesn't care that mass m being thrown out of the nozzle with velocity v consists of - H, O2, H2O, steel balls or foam - doesn't make difference as long as it is of mass "m", and the aircraft needs to come up with that mass somehow - carry it with itself or gather from outside (and accelerate the mass or try to impact momentum on the already fast moving mass).
Take the points above, add the simplicity and low weight of the rocket engine in comparison with air breathing engines and you will see why rocket engines are dominating the arena.
2. Scramjet's have already been demonstrated at over Mach 9.5 and are still more efficient than rockets at those speeds. (aka more thrust per unit fuel.)
3. Scramjet's are actually fairly simple designs compared to a traditional get engines. (Modeling and testing them however is much harder.)
Granted, there are plenty of downsides which is why we have not built anything like that. But, the issues are far more in line with heat dissipation and drag vs. limits on the basic physics. Still the main limitation seems to be the far lower thrust-to-weight ratio.
that exactly the basic physics limit of the scramjet that i was talking about : "the other side of the same issue - trying to impact even small amount of additional momentum on the already fast moving air"
It's counterintuitive, but re-entry vehicles are typically bluntly shaped because it reduces the heat load on the nose cone by pushing the bow shock further out in front of the craft. The downside of this is higher drag and less lift, so ICBM warheads fall more than they glide.
Wait, but don't ICBMs have like 40 min strike time for any target in the world since, like, sixties? (Ok, in the sixties they couldn't aim this fast).
Then again, it is each generation's duty to hope to rise above the last. I hope that friendly attitudes and cosmopolitan cynicism can combine to keep conflict from flaring up, and to snuff out any little conflagrations that spring up instead of escalating them out of pride and fear. But inevitably we must plan for the opposite contingency. At the very least we must plan for mistrust and tension, and therefore, at the very least we cannot depend on a weapon that is indistinguishable from a first strike. The only reason to develop it is for research purposes.
P.S. Oh, man, isn't it a tempting idea to snuff out your main creditor? Nobody in the Congress has a more realistic plan for getting rid of the national debt.
This is a tech experiment. It may lead to advances in airplanes, but I highly doubt it is cost-effective compared to an equivalent missile that just slams home.
Mostly the letter "B" for "ballistic".
You can turn while flying. You can't turn while falling. You can stick out a little control vane to try to change course a little bit, but at that sort of speed, in that sort of atmospheric density, and bearing in mind that during re-entry anything that is at all pointy will get burned off, I doubt you could do much at all.
That this was a "plane" is inconsequential, and not even interesting, in terms of missiles - that they had at least minimal control at that speed is either a breakthrough, or duplication of existing techniques that can be applied to big-ass missiles (there, swap the B with "Big") more easily and more cheaply than to something designed to be re-used. Which, given the difficulty in adding controllable movement at such speeds to something way more complex than a one-use missile, implies to me that the techniques have existed for a while in cheaper forms, and this is just the first time they've been able to do it and (nearly) recover the device.
That's significant, but it's not a game-changer for missiles or making things go boom.
Ah, but then you're no longer falling.
You're not even "falling with style".
But apparently state of the art re-entry vehicles are capable of much more complex maneuvers including 180 degree turns (heading on ground, not the full 3d vector obviously).
The US has had this capability since a research project in the 1980s. Some form of it is deployed on Trident as well as the comparable UK and CH systems.
There is very little published on the topic, but if you start researching the AMaRV project you'll find some details and claims. Of course there's really no way for someone outside the defense community to confirm these claims, but I know of no physical reason why they couldn't be true.
now, to add to that: the radius of a 1 g turn at mach 20 is 4444 km. The radius of the earth is 6378 km. They've got to at least consider orbital mechanics just to hold altitude constant. Able to maneuver and highly maneuverable are two different things. The Titantic was able to maneuver. Just couldn't move fast enough.
Now, let's think about some other fun stuff, everybody join in.
Here's one: at mach 20, you need something along the lines of the shuttle's thermal protection system. We're talking plasma hot. Wrap this thing up in 3 inches of glass and I'll bet you've lost significant payload volume.
Same principle as a http://en.wikipedia.org/wiki/Railgun where projectiles travel at 5,400 mph, and the gun can be situated on an aircraft carrier.
On that note, the article above mentions railguns as way to launch spacecraft into orbit: applicable for this Mach 20 plane.
2. The US already has long-range assassination hit squads, e.g. Osama Bin Laden's Assassination
Plus its non-ballistic flight path and high degree of maneuverability probably allows it to evade most anti-aircraft and anti-ballistic missile defenses.
Scary stuff.
Edit: Grammar and spelling.
In either case, it seems moot in today's day and age. What's the difference between firing a missile at enemy headquarters with the intention of killing the general and senior staff, and an assassination?
It seems today that 'assassination' is simply pursuing the usual methods of war against a specific target.
There were no basis for the accusations but he understandably pretty unhappy as the penalties for being found guilty could be pretty severe.
You hear the scream of a missile overhead. It passes. Sometime later you will die.
That's a horrible way to go.
I don't know why she swallowed a fly.
I guess she'll die...
[related - does the telemetry problem mean that if something like this ever went into production, it would be largely autonomous?]
Assuming it's going in a straight line (Which wouldn't be unreasonable at that speed), you just need to send something up to block its path.
[edit] now if the enemy builds its own with the same speed / range then all bets are off
This is just one more in a long line of "unshootable"/"unsinkable" projects which will prove the opposite.
http://www.raytheon.com/capabilities/products/ekv/
Inevitably, someone else probably has it too.
Any Mach-20 vehicle is going to have an extremely limited thermal tolerance, and thermal shielding is likely to be applied specifically to those elements of the vehicle which require it for aerodynamic reasons.
Lasers could acquire and track with the target despite evasive maneuvers better than any kinetic weapon. Though a large-dispersion scatter weapon (ball bearings) would probably be sufficient. Each bb impact would be about the equivalent of a gram or two of TNT.