NationStates Jolt Archive

Aircraft designers are sought to codify a large-scale design concept that has been RP-ed in the past, and is now being examined for possible sale.

Design is post-modern tech, and will, when coupled with an experimental weapons system (to be detailed publicly when the complete package is available), contribute substantially to end users' offensive military effectiveness.

Expressions of interest can be entered here, response to nations expressing interest will be via telegram, due to the confidential nature of the technology prior to release.

Needless to say, those who assist in this regard will recieve a portion of the production run and, believe me, you will not be disappointed...

OOC: How is anyone supposed to know whether or not they're interested when you won't say even OOCly what it is?

This is something that, to my knowledge, has never been done before on nationstates. It uses contemporary or very slightly post-contemporary technology, put together in a highly unusual form, to deliver maximum air-to-ground precision and lethality, while employing exceedingly above average self-defence measures.

At the risk of sounding stuck up, I am an army officer, and this thing, were it in existence today, would seriously revolutionise the way war is fought.

[OOC: May I point you to the NS Draftroom (http://z13.invisionfree.com/The_NS_Draftroom/), where there are people who can help you design. If you wish for more information, please telegram me.]

[OOC: May I point you to the NS Draftroom (http://z13.invisionfree.com/The_NS_Draftroom/), where there are people who can help you design. If you wish for more information, please telegram me.]

Ta

And bump...
There would have to be a willing and able designer looking for something different...

I am interested. If only to see this concept you've got...

Kinsong Aerospace would be interested in aiding you with your design needs. We posess extensive experience with conventional and unorthodox designs and systems, and will be able to provide expert assistance to your project.

[OOC: Sounds interesting, would like to know more, etc etc.]

I'm an aerospace engineer, but I'm a bit busy. I can critique the general concept, at the very least, and better it be critiqued now by someone with professional knowledge in the field and done quietly rather than... well... it turning out to be a bad idea and the critiquing be made public.

Telegram going your way, Halle Iesu, Khrrck and Scolopendra...

Some initial opinions sent back.

Response returned. Good thoughts, generally.

Wow. Ouch. That is going to hurt.

But that design is just so far above my head that I don't know where to start...

Sorry, I'll leave this to the professionals...

Glad you like the idea. Surface fleet based naval power will be relegated to the history books once this thing takes to the sky, for one thing...

Professionally, I don't like it. It ignores the real challenges to hypersonic flight (1. subsonic to hypersonic transition, 2. heat load, 3. propulsion integration into airframe), assumes a greater understanding of the operation of the human brain on a logic-gate 'programmable' level than I think is reasonable within the confines of close future (no matter what Kurzweil says), and has a completely extraneous weapon system.

I'm not one to get in the way of people's handwavium, though, and all of these hurdles are physical ones that, to get around, don't require breaking any physical laws. Just realize that it's a bit harder than it seems. Also, if anyone does end up coming up with some (fake, but that's just professional elitism talking) numbers and pictures for the guy, DON'T PUT A POINTY NOSE ON IT. Every concept hypersonic vehicle you've ever seen in the past twenty years has a blunt nose on it for a reason.

And it has been done before. Poorly. <_<

I was running on the assumption of a deflagration-to-detonation transition, although my solutions to heat load so far have been the simple application of tungsten carbide along leading edges... unsure of the viability of that one..

The platform was anticipated to be fairly large, to allow for the stablisation of imagery equipment, and to mitigate the vibration generated by the PDWE.

And, out of curiosity, why the blunt nose? Not taking the piss, genuinely curious...

If you make the nose pointy, the shock impinges on said point and you get a lot of flow-to-hull heat transfer from convection and boundary layer conduction. It's bad. Lemme see if I can find an example...

http://www.hq.nasa.gov/office/pao/History/x15conf/ico-14.jpg
Ventral rudder, X-15. The shock impinged on that bit that's all melted away there. Just an example of shock impingement (sharp-nosed things they managed to get up to Mach A Lot never had enough left to take a good picture of).

If you make the nose stubby, though, it acts as a flat plate and forces the formation of an oblique shock away from the nose, so the heat transfer is mostly radiative with a small bit of convection from the slowed post-shock flow. That's still a lot, though; that heat is what brought down Columbia.

Tungsten-carbide has a very high heat load, yes, and hardness--that's why it's used in mining. Problem is that it'll act like a heat sink and eventually melt under extended flight. As a structural metal, though, it's no better than titanium in strength (in terms of pascals per kilogram, is actually much weaker than titanium, steel, or aluminum), is brittle, and like all hard brittle things is difficult to machine into parts. Heat-sinking is a bad tactic to use in hypersonics because, eventually, you will melt. The Space Shuttle, were it to be used as a hypersonic vehicle, would probably melt due to the heat load, and it has an absolutely absurd radiative cooling efficiency. When it lands once the crew's off they have to send in coolant trucks to remove all the heat (energy) stored in the tiles. If tungsten-carbide were a magic cermet, more things in aerospace would be made with it (it's been around since at least the '70s. Even Monty Python's Flying Circus mentioned it).

Deflagration-to-detonation transition means a long drag-producing tube, and that drag translates to a lot more heat. Now you have something the Space Shuttle doesn't, that being an exhaust pipe you can turn into an open-cycle cooling system... but that's also what you're exploding, so I'm not sure that will be too effective. I'm thinking radiators on the top of the wing area (and given that this would probably be your old waverider surfboard or maybe a conic sliver, that's the entire top of the plane essentially) glowing white-hot from a radiator farm. Which would be sorta cool.

While tungsten-carbide coated MAC rounds were cool in Halo, why fire a hypersonic round from a hypersonic vehicle when, well, you've already got plenty of velocity and KE to kill whatever you please? If you really must make the bullet go faster, have it carry rockets or some such; the weight will be well underneath the magnetic contraption necessary nowadays to pull off a no-barrel-contact coilgun.

After thinking about it some more in a TG, yeah, both fore and aft firing guns have the problem of shooting through powerful Mach 10 shocks. The shock profile for any given vehicle without noise-reduction shaping having been done to it (and we don't want to, really, as it tends to increase drag and thus friction heat), looks something like this.

http://www.4p8.com/eric.brasseur/swlb1.gif

The fore and aft shocks are more or less of the same strength (the aft ones are a bit weaker due to entropy, but whatever) and firing through a Mach 10 shock wave means one is having to deal with a big flow discontinuity. It'd probably severely hamper targeting through it with dumbrounds and tend to break things like missiles and rockets (unless they're designed to go still faster, which is sorta silly).

So I thought. Put the camera in front for target acquisition. Aim plane to fly above target. Then drop some sort of KE kill vehicle out the bottom; it's programmed to fly/fall behind the plane and stay within that region of "moved air." If it's a high-altitude strike, then once the shock dissipates enough, it fires to Mach A Lot and kinetic-kills. If it's a low-altitude strike, the target gets to enjoy stupid overpressures from a Mach 10 shock wave and then gets hit with a Mach 8-something KKV before getting overpressured suddenly again. Problem with a "low-altitude" strike is that the heating issue would be even worse... hmmm.

Your guesstimation of aerodynamic conceptualisation is spot on. Wave rider or conic sliver indeed.

I like your radiator farm idea. But nevertheless what material would be suitable for the elements of the platform that are subjected to most air friction?

The weapon is not designed for air-to-air function. It's an air to surface system, designed for both hard and soft target kills, high rate of fire, and ability of the system to track and adjust its own fall of shot... the projectiles glowing white hot through the atmosphere making the firing easy to see...

Again, in theory.

You could probably get away with tungsten-carbide on the leading edges, with a steel skin overall and some sort of active cooling loop underneath. This means the plane will be heavy, but those are the breaks.

Concerning the strike mission, rate of fire is really an academic number when your engagement time is as small as a Mach 10 attack run. Additionally, if you're going Mach 10, you're not going to be doing it in anything other than an approximately straight line (neglecting the curvature of the earth) on the tactical scale. The concept of 'turret buffet' at Mach 10 scares me, so the gun would have to be fixed. Shot fall adjustment would thus require maneuvering the entire airplane, which isn't going to be more than maybe a degree in a few-second engagement time (remember, the target has to be acquired and verified first, so you hit the tank and not the oddly shaped playground equipment full of kids next to it).

Your average strafing maneuver consists of diving and pulling up so you drag the shot placement over the target. Again, given the flight envelope, I don't see that working for a near-modern technology hypersonic vehicle. Given that bullets are generally kinetic kill and you're certainly going faster than any bullet... you've already got all the speed you could ever want in a strike mission, now that you've got over TNT explosive equivalency in kinetic energy alone. Guidance packages are cheaper by the day, and this thing is going to be expensive anyway--no point in cheaping out on weapons guidance. A rocket is also less of a stretch than a coilgun, and probably less expensive for the same amount of energy-on-target. It would also make the plane lighter as you wouldn't have to have some sort of generator for the magnetic fields: remember, a PDE has no turbine and so your propulsion doesn't make any electrical power for you.

What about a recessed turret off some description? Would that negate some of the issues (although again accepting the increased weight and size of the aircraft)?

Recessed turret is false data. At that point you're talking more of a barbette, and it's still going to be a bulge on the hull with its own minor shock flowfield properties. Turret buffeting was a problem on the P-60 Widowmaker, and while it was high performance it was nowhere near transsonic, much less hypersonic.

Generally you need the gun of an aircraft to shoot things with a greater muzzle velocity than the aircraft, to make sure you don't end up shooting yourself down. Right now most aircraft cannon have a muzzle velocity around Mach 3 or so. The Mach 3 shockwave of a light (20 to 30 millimeter) cannon round is nothing to write home about, and thus isn't an issue, even at thousands of rounds a minute. The Mach 10 shockwave of the same projectile at a high rate of fire is scary for the reason of the X-15 picture shown above. These are all reasons that I'm really not liking the idea of a gun-based weapon system.

(On a side note, this (http://www.hq.nasa.gov/office/pao/History/x15lect/structur.html) is a good read for a ~Mach 6 plane. Yes, it's the X-15, but it gives you a broad idea of what to expect.)

Then there's the problem of adding weight and adding weight until it simply won't fly anymore. Let's assume that an all-steel structure and its active cooling ends up being lighter than an aluminum internal structure (a la the space shuttle) and its active cooling. It's still going to be much heavier than a conventional aluminum structure (so would a titanium structure with active cooling, probably, but I don't want to make this cost a ludicrous amount). Just the structure and heat management alone will make this a heavy beast. Start adding on things of dubious utility like turrets and heavy guns and it will start getting geometrically (not linearly) bigger, due to the necessity of balancing wing loadings and sizing the propulsion to make the speed and sizing the structure around the propulsion etc. Bomb bays are a lot simpler, and more importantly, lighter than large guns when it comes to equivalent energy placed on-target.

I think what we're missing here is that any gravity bomb dropped by this thing will as a rule be going hypersonic, and much faster than any reasonable cannon round would. The aircraft itself plays the role of cannon barrel of accelerating the round and imparting energy to it. All we need is a reasonable muzzle, aka a hole, to push the round out of. If it's not doing AA, then it doesn't need to shoot in front of itself as it's not an interceptor or dogfighting or doing anything spectacular like that.

So the idea shoddily pictured below wouldn't work?

(Barrel Mechanisms up here, rotating around the muzzle below)
_____________________________| |_____________________

With more material to the right to deflect airflow away from the mouth of the muzzle.

Is it pointing down and heading towards the right? At that point, just make it a canister launcher--you probably don't have to impart too much downward velocity to the projectile and, well, conservation of momentum means that even just dropping a bomb is going to make the plane jump up a little. Shooting bombs straight down may be a little more problematic that way.

Could the coil gun be fired from an aperture like that?

Probably, but then it wouldn't be very long and the muzzle velocity not that great. I really don't see the point in adding a coilgun for the sake of saying "it has a coilgun" but if you're dead-set on it I can't stop you.

Just establishing the feasibility of the delivery mechanism. The coilgun enables generation of high penetrating power, even if the platform is travelling at lower speeds. Further, if more than simple gravity is relied upon, then ballistic targetting is probably much easier.

Plus, we can use much of the research that went into this weapon system to generate similar ground-to-air systems...

If you're worried about penetration power at low speed, then drop a proper tank-killer bomb. If you're worried about ballistic targeting, put fins on your bombs and you're not limited to ballistic targeting. If the platform isn't going Mach A Lot over enemy territory, then it's a target: hypersonic wedges fly extremely poorly at lower speeds.

My general argument--from the standpoint of a professional engineer--is that it's a bad idea to put something on a vehicle that doesn't add to the mission. If the mission is fast ground strike and reconnaissance, and we've decided to do it hypersonically, the strike mission is better served by twenty tons of bombs rather than ten tons of gun and ten tons of bomb ammunition. Going hypersonic means that any projectile already has the KE it'll ever need; adding a coilgun for the sake of, well, having a coilgun and trying to insist on ballistic targeting doesn't really achieve much. Besides, glide-path bombs and shells are generally far more accurate than bare-bones ballistics.

I'd recommend putting the coilgun on a dedicated ground chassis (like a tank) where it belongs. Maybe shooting Mach 12 shells to counter planes like this. But professionally, and as a very minor airpower mind myself (officer training for two years), I see no point to the gun system. It requires independent power and thus an independent generator to power it (unlike the DEW considered for the F-22 and F-35, you don't have the luxury of a turbine in your propulsion to use as an electric generator), it reduces effective energy on target compared to bombs, it doesn't increase the engagement profile appreciably, etc. etc. etc. It is shiny, but that's all it is.

Like I said, I can't stop you. I can be an engineer though, as asked, and point out why I think it is an extraneous idea.

Would glide-path bombs have the same targetting area as the projected kinetics?

Given you're probably dropping them from about 20 to 30 kilometers up and they have plenty of room to glide... I'd say a much greater targeting area, especially as they could fire 'off-bore' so to speak. JDAMS, which are the bottom of the barrel as bomb redirection packages go, are usually launched 20 km away from a target and have a decently wide arc of off-bore turn. The more missile-like it gets, the bigger the spread can be.

The on-board ammunition would be in far shorter supply than the projectiles for the high-bore gun. Also, guided and semi-guided weapons can be intercepted... the same is not true of bullet-type weapons... at least to my knowledge...

Thoughts on that?

If you drop a bomb at Mach 10, the bomb itself will at least initially be going Mach 10 as well. This is much faster than any reasonable cannon or artillery shell and thus makes it much less likely to be intercepted. Bullet-type weapons can be and have been intercepted (see the THEL system for anti-artillery and anti-mortar applications), it's just usually harder because they normally go faster. KKVs dropped by this thing are already going much faster than your average bullet, and would be proportionally more difficult to intercept.

Killing hard targets isn't a matter of number of rounds, it's a matter of effective energy on target (compare a 30mm Bushmaster stream against a hardened target as opposed to, say, a single 120mm HEAT round. Or that the British in Iraq have been using inert concrete bombs to excellent effect against enemy vehicles, and this from mere [i]Typhoons). A high rate-of-fire is made negligible by the very short engagement time of a hypersonic pass, so having a greater number of shots but lower energy-per-shot is not an advantage. This thing won't have the time to even put too many rounds near the target, much less correct its own aim even assuming a turret wouldn't make it fall out of the sky (and asking for a turret on a near-modern tech hypersonic aircraft is asking for a bit too much). In the same amount of time one can pickle a few bombs which, due to guidance packages, have a much higher chance for hitting the target and, due to their immense speed (in general) and mass (comparative to a tiny cannon round), have much higher energy-to-target per round than a burst from a theoretical extra-heavy coilgun. A more conventionally armed (bombs) hypersonic aircraft is thus capable of spreading more energy to more targets than a similarly sized one with a coilgun would, because more mass (which directly relates to energy-to-target in KKVs) would be dedicated to the actual reach-out-and-kill-people instrumentality, rather than the mechanism used to deliver said instrumentality.

It can't fire the coilgun to the front because then it's firing into the bow shock, which being an extremely turbulent chaotic flow will ruin its ballistics. It can't fire the coilgun to the rear because not only does the aft shock do the same thing, firing a Mach 10 bullet backwards from a Mach 10 airplane means that to its targets on the ground they just got hit with a Mach nil paperweight. It can fire the coilgun downward, but from an essentially fixed position with a shortened maximum potential barrel length (as hypersonic vehicles are not usually what I would call proportionally tall) and, if not timed right, will hit one or the other shocks anyway. At that rate, one may as well go for the MetalStorm solution of shooting lots of things out the bottom, but you (as the executive in charge of the program) have demanded accuracy, not a wall of hot iron.

At this point, think that all of the aircraft to have carried heavy gun armament (we're talking field guns of 75mm or greater) always had them in fixed emplacements and were of relatively low performance. Yes, an AC-130U has a 105mm howitzer shooting out the side. This is because it flies slow enough that an orbit with a howitzer's standoff distance makes more sense than having the thing fly overhead and drop bombs. Given that a AC-130 has a service ceiling of 30,000 feet and is naturally limited to middle-to-low subsonic being a turboprop... ya, it's air-defense fodder. This plane goes faster than any modern technology military direct-fire ballistic projectile and, as said previously, has already served the purpose of gun. Anything it merely drops is already a KKV. If you need it to fire a stream of smaller things, have it drop a string of hypersonic low-caliber rockets. At that point the motive system for the round is this relatively light, compact solid fuel rocket core rather than a heavy, large electromagnetic containment system that requires a heavy, large generator to support it.

Good points, all.

What sort of bomb-load is likely?

Further to that, what would have to be put in place to both accurately direct the weapons, and release them. Conventional bomb-bay doors would be shorn off by the air pressure, surely?

*cough*bombtunnel*cough*.

this sounds similar to something i've been thinking of for a few months now, a hypersonic bomber. where they're different seems to be role - this thing an attack aircraft, my idea a strategic bomber.

open a clamshell hatch in the back & let the vacuum suck out the munition - don't have to reduce speed by much to make this effective, afaik.

i'm not too sure on the effectiveness of a hypersonic attack aircraft, but t'aint my project, t'aint my gov $$.

Hmmm. Could make the bomb doors open inward. It's not like you'll have any lack of internal volume anyway (you'll probably actually want to make it larger than it has to be so you have more radiative surface area; if you look at a cutaway of the space shuttle its wings are mostly empty volume). Clamshell hatch would also work, or something like sliding doors. A bit heavier, sure, but those are the breaks. That's all you need to release them.

AGM guidance nowadays is mostly done solely by the bomb, with the rare exception of laser-guided bombs and teleoperated bombs. Pretty much, before release, the onboard computer tells the bomb guidance package "this is what you're going to see when you're kicked out; your job is to hit the thing highlighted by this box here." The bomb then uses image recognition and its fins to guide itself to the target. Cruise missiles do this, as do some anti-armor weapons (their ability to accurately identify different kinds of heat signatures is actually quite impressive). If you've got a secure laser-communications link (radio is out of the question because you start getting ionized air) you can have telemetry between the bomb guidance package and the aircraft's optics package, which act as stereoscopic vision and, if the software's written right, allows the onboard guidance recognize what topography it has to deal with.

I anthropomorphize, of course, but it makes the discussion easier.

Likely bomb load... depends on the mission. Assuming you need a delicate touch, you're going to have some sort of very small inert weapon which consists of mostly a guidance package, enough metal to allow it to survive it's own speed, maybe an ablative shell (or maybe not, if it can handle the heat load), some fins, and not much else. At Mach 10 it's worth its mass in dynamite so you're not going to get below large hand grenade / land mine yield; then again, if you need a particular sucker dead without anyone else getting hurt you'll send in black ops and snipers and whatnot. Or pay some thug to mug him lethally in an alley. Whatever.

If we're talking anti-armor then a bunch of 100 to 1000 kilogram inert bombs will do nicely. Yes, they're not much for piercing armor, but the momentum transfer will literally squish tanks like tin cans. If you want more subtlety, some self-forging copper projectile long-acronym warhead would do nicely, but that's a matter of taste and funding.

Anti-bunker, 1000+ kilogram block of steel/whatever built to do the whole liquify-and-kill thing on impact.

Anti-personnel, either a concrete bomb or a cluster concrete bomb (also known as "gravel"). Maybe coated with some sort of ablative or metal covering so they'll survive the trip to the ground. Okay, so you're essentially hurling flaming rocks at people. But seeing that sort of thing take out the company next to you has got to be horrible on morale.

Just to be mean to people, you could also have it fire Mach 10+ hypersonic rockets in case you want still more KE involved. This would just require the inclusion of, well, a rocket. And it'd have to be designed to survive (for a very short time) at Mach 12 to 18. Doable, no doubt.

1000 kg inert bomb, slamming into the ground at Mach 10?

That's not an anti-armour/anti-bunker weapon. That's almost a tactical nuke. 100kg sounds far more practical, and enables a much larger number to be carried...

Unless I've missed something... which I may well have...

Mach 10 is -just above- the mark for TNT equivalency. So 1000 kg at Mach 10 is about 1000 kg of TNT. Just a ton, not a kiloton. Definitely sub-nuke.

I'll remember that snippet about Mach 10 to TNT equivalency...

Will a plane flying parallel to the ground impart the same velocity to a projectile released perpendicular to its flight path?

And, it would seem that I did indeed miss something :P

Will a plane flying parallel to the ground impart the same velocity to a projectile released perpendicular to its flight path?
Of course it will. The projectile and the plane both start at the same velocity, right? The projectile won't just come to a dead stop horizontally relative to the ground just because it was let go. It will slow down due to air resistance, but that's why I suggest rockets a lot.

This (http://www.physics.ucla.edu/demoweb/demomanual/mechanics/ballistics/galilean_relativity.html) explains it simply enough.