Hyper Velocity Projectile
The Hyper Velocity Projectile (HVP) from BAE Systems is the latest fad that military observers have latched onto. The HVP can be fired from any gun, travel several times around the Earth, has a speed of Mach 328, cost nothing (might even generate a small profit per shot?), and is a guaranteed one shot kill against any target on land, sea, or air … At least, that’s the impression one gets from the unbounded hype surrounding this technological wonder. Let’s look a bit closer and see where the reality lies. Note that it is difficult to separate reality from claims in the literature and to determine what actually exists versus what is just proposed or planned.
To refresh, the HVP is a kinetic (meaning non-explosive) projectile that can, indeed, be fired from multiple weapons such as a rail gun, the Army 155 mm howitzer (with suitable modifications to the gun), and the Navy 5” gun. The BAE product brochure claims that the HVP can be fired from the currently useless Zumwalt Advanced Gun System (AGS). That is an unproven claim, at the moment. Aside from the unique and non-standard barrel of the AGS which seems to preclude any round other than the LRLAP, the entire automated ammo handling system would have to rebuilt or the HVP would have to be packaged in an exact duplicate of the LRLAP round – doable, presumably, but expensive.
The projectile is a common, dart-like body that is fired from various weapons via specialized sabot adapters unique to each weapon. The flight body is 24 inches long and weighs 28 lbs. The payload is 15 lbs. (2)
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| HVP |
The HVP is claimed to travel at speeds of around Mach 7 (5000 mph or so). This presents both benefits and drawbacks. Presumably, the speed is less when fired from a conventional gun as opposed to a rail gun.
The HVP is transitioning to the Office of Naval Research (ONR) for additional development.
Now, let’s look at some specific aspects and features of the HVP.
Firing Rate. From the BAE product brochure (2), here are some projected firing rates for various weapons.
Mk 45 20 rounds per minute
AGS 10 rounds per minute
155 mm Tube Artillery 6 rounds per minute
EM Railgun 10 rounds per minute
Range. From the BAE product brochure (2), here are some projected ranges from various weapons.
Mk 45 40+ nm
AGS 70 nm
155 mm Tube Artillery 43 nm
EM Railgun 100 nm
Guidance. The HVP is claimed to be guided but that’s true only in a limited sense. The guidance is GPS and is applicable only against fixed, land targets with known GPS coordinates. Useful guidance is not possible against moving land targets or aerial targets due to the extreme speed of the projectile.
One of the “side effects” of speed is inertia. The faster an object moves, the slower and harder it is to alter its course. Faster means a larger turn radius. A WWI Fokker Triplane has immensely greater maneuverability than a modern F-16 because the F-16 has such high speed. An HVP traveling at Mach 7 cannot easily change course. An incoming cruise missile traveling at high subsonic speeds, for example, would be far more maneuverable than a Mach 7 HVP which is, for practical purposes in that scenario, ballistic and non-maneuverable.
Warhead. The HVP is currently a kinetic weapon with no explosive warhead. It must hit to kill. Various reports have suggested that an explosive warhead could be developed that would enable proximity fuzed projectiles for anti-air defense.
Cost. One of the much-ballyhooed claims about the HVP is the low cost per round compared to missiles. This is true but only in an unrealistic sense. The original cost of an HVP round was claimed to be around $25,000. The current cost estimate is $86,000 per round (1) though it is unclear what version and capabilities that cost represents. This is still much less than, say, a Standard missile but only in a one to one comparison. In a realistic engagement scenario the costs are much closer. For example, Breaking Defense offers an example in which each HVP is assumed to have a kill probability of 10% (pK=0.1) and 22 shots would give a 90% chance of killing the target. Well, 22 x $86,000 = $1.9 million dollars which is the same realm as a Standard missile. Thus, cost is not a clear cut advantage and it could turn out to be more expensive over the course of an engagement. Note that the 10% pK was a number made up by Breaking Defense for illustration purposes. There is absolutely no data for actual kill probabilities. Personally, without a proximity fuzed warhead, I’d estimate the pK to be 1%-5%, at best. If true, the cost “benefit” is even less.
Lethality. This is a difficult issue to quantify. Yes, we can calculate kinetic energy for the projectile but that’s only part of the story. Consider the example of a bullet fired from a handgun at a piece of paper. Based on the kinetic energy calculation, the paper should be vaporized and yet the only damage done is a hole the size of the bullet! Why? Because the kinetic energy wasn’t transferred to the paper target. More accurately, the bullet had POTENTIAL energy that wasn’t converted to actual kinetic energy upon impact (I’m grossly simplifying some physics here for sake of illustration). In simplistic terms, the paper did not offer enough resistance to the bullet to allow the bullet to convert its potential energy into kinetic energy on the target. The bullet passed through the paper, converting only a very tiny fraction of its potential energy, and retained most of its potential energy.
Similarly, if an HVP hits one of today’s thin-skinned warships or even thinner-skinned missiles, will the projectile be stopped, thereby converting all of its potential energy into kinetic energy and causing significant damage or will it pass through, like the bullet through paper, and convert only a portion of its potential energy to kinetic energy? The astute observer will note that the impressive videos of rail guns and HVP rounds always show the damage done to targets that are several inches to many feet thick of steel or some such material. What would happen if a rail gun HVP projectile impacted a 3/8” thick metal sheet, as is typical of a modern ship? Undoubtedly, the projectile would pass through, almost unaltered, leaving behind only a hole the size of the projectile. In other words, it would cause very little damage.
Now, in an actual ship, there would be multiple bulkheads (even thinner!) and pieces of equipment (really thin!) that the projectile would encounter on its path through the ship. Each would cause the projectile to “dump” some potential energy but would the cumulative effect be enough to achieve the massive energy conversion that would constitute significant damage? I have no idea but I suspect not. Of course, the projectile might also encounter flammable fluids leading to fires or sever pipes and electrical lines causing more damage. I suspect, though, that if a HVP were fired at a ship, it would pass straight through and cause relatively little damage. This is just semi-informed speculation on my part. One would hope that someone in the Navy has thought this through before we commit to this weapon. Of course, one would have hoped that we would have thought about galvanic corrosion on a ship (known about since the days of sail) and yet we failed to provide galvanic protection on the LCS so I make no assumptions about what the Navy should have considered.
Of course, one could imagine using a HVP with a contact fuzed explosive warhead. That would solve the problem of pass-through and provide localized damage effects. The 15 lb payload, however, drastically limits the magnitude of the explosive effect. It is also unknown whether the entire 15 lbs is available for explosive or whether a significant portion would be devoted to fuzing, electronics, etc. While the 15 lb compares favorably to the 5” gun round burst charge of around 8 lbs, the 5” round is a heavier walled shell which contains the burst and amplifies the damage effects versus a thin walled, uncontained burst. I have no idea what the wall thickness of the HVP is but I suspect it is not very thick.
All of this leads one to ask whether there is any actual gain in damage effects over those obtained from a conventional shell.
That takes care of anti-ship lethality. Next, let’s look at land attack.
For a specific, hard target such as a building or hangar, the kinetic HVP will likely cause significant damage. However, it has a significant limitation in that a near miss will cause no damage. The projectile will simply bury itself in the ground. There is no explosion. It’s a case of exact hit or no damage. Conversely, a conventional round with an explosive warhead may well cause damage from a near miss due to the explosive effects and shrapnel. Of course, a warhead could be added to the HVP but with a payload of only 15 lbs, it wouldn’t be much of an explosion. Thus, the HVP looks to be an excellent choice for a specific, hard target but of limited use in general bombardment and useless for suppressive fire (one of the major uses of naval gun fire).
I have been unable to determine which HVP warheads other than the kinetic (inert) version actually exist, if any. My impression is that all are just proposed versions.
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| HVP Sabot Forms |
In summation, the HVP appears to be a potentially useful weapon for a limited target set, primarily fixed, hard, land targets. The projectile is very long on claims and proposals and very short on demonstrated performance, as is typical of new, developmental weapons. It is well worth continued development but appears to be well short of being the miracle weapon that its hype would suggest.
This is one of those subjects that some readers may have more current information on than I do. If so, feel free to add information via the comments. Additions will be greatly appreciated. Just be sure to offer supporting documentation.
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(1)Breaking Defense, “$86,000 + 5,600 MPH = Hyper Velocity Missile Defense”, Sydney J. Freedberg, Jr., 26-Jan-2018 ,
(2)BAE Systems website,
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