HVP Speed Lie

As you know, the Navy has, for the moment, shelved the electromagnetic rail gun in favor of firing hyper velocity projectiles (HVP) from 5” guns.  The HVP’s distinguishing characteristic is its speed which is reported to be Mach 3 (3344 ft/sec).  This leads the manufacturer, BAE Systems, to make all sorts of amazing claims which, if they are to be believed, would mean a single 5” gun is the only weapon any ship will ever need!  I’m being a bit facetious, here, but not much.  BAE and the Navy claim the HVP will handle land attack, anti-surface, AAW, and ballistic missile defense!

By the way, hyper velocity is defined as greater than Mach 5-8, depending on what definition you choose.  Mach 3 is not hyper velocity.  Moving on …

Let’s take that distinguishing characteristic, speed, and check it out.

The HVPs from a traditional deck gun will be slower than one launched from a railgun — a little over Mach 3 versus Mach 5 [ed: railgun projectile speed] — but still more than double the speed of an unguided regular shell from the service’s Mk 45 five-inch gun … (1)

Mach 3 = 3344 ft/sec

Wow that’s fast!  Double the speed of a standard round from the Mk45 5” gun!  Wow!  Just Wow!

Just out of curiosity, what is the speed of a round from a 5” gun?  Well, since the HVP is double the speed then the 5” round must be half the HVP, right?  That would put the 5” round at 1672 ft/sec. 

Just for giggles, let’s see what NavWeaps says the 5” round muzzle velocity is.  NavWeaps gives the following data. (2)

5”/62 round types:

Mark 80 HE-PD - 67.6 lbs. (30.7 kg)
Mark 91 Illum-MT - 63.9 lbs. (29.0 kg)
Mark 116 HE-VT - 69.7 lbs. (31.6 kg)
Mark 127 HE-CVT - 68.6 lbs. (31.1 kg)
Mark 156 HE-IR - 69.0 lbs. (31.3 kg)

5”/62 round muzzle velocities:

Mark 80 projectile with Mark 67 cartridge - 2,725 fps (831 mps)
Mark 80 projectile with EX-175 cartridge - 3,450 fps (1,052 mps)
Mark 91 projectile with Mark 67 - 2,750 fps (838 mps)

So, the 5” muzzle velocities range from a low of 2725 ft/sec (Mach 2.4) to 3450 ft/sec (Mach 3.1).  Compare that to the HVP’s speed of 3344 ft/sec (Mach 3).

We see, then, that the slowest 5” round is 81% of the HVP speed.  The HVP isn’t double the speed, it’s only 1.2 times faster which is only 23% faster!

The fastest 5” round is actually faster than the HVP!

What’s going on here?  The HVP is only marginally faster than the slowest 5” round.  Someone at BAE or the Navy is lying confused about their facts.  Does the Navy really not know basic arithmetic?  We’re being fed a lie.  As we noted, the hyper velocity projectile isn’t hyper velocity, at all.  Ignoring that definition inaccuracy, the HVP is barely faster – or actually slower – than a standard 5” round.  Again, we’re being fed a story that doesn’t match reality.

Setting aside the lying confusion, does it really seem plausible that a 23% increase in projectile speed (or slower than a 5” round, depending on the projectile!) will grant all the magical capabilities that BAE and the Navy are claiming? 

Projectile guidance is certainly a useful capability, one would think, although, depending on the guidance process, likely only useful in certain circumstances.  As I vaguely understand it – it hasn’t been publicly discussed in any detail, as far as I’m aware - , the guidance will be a very small millimeter wave (MMW) sensor/seeker.  The inherent drawback to a MMW sensor/seeker packaged in a small 5” projectile is that the power output of the sensor is limited and, thus, the detection range is limited.  This means that the projectile must get close to the target to be able to “see” it.

Presumably, the projectile is unguided until it reaches a calculated near-intercept position and then guides to the target in the terminal phase, assuming it sees a target.  Herein lies the problem. 

The short millimeter radar detection range is problematic for use in AAW when the convergence speed of the target and projectile may approach Mach 4-5. By the time the projectile is close enough to detect the target, the target is almost past!  The time available for guidance maneuvering is almost zero. Unless the seeker can detect the target from much farther away, a guided AAW-HVP will not be any more effective than a standard 5" round.  For example, at a combined closing speed of Mach 4, if detection occurs at 1 mile, the target will be past the HVP in 1.2 seconds. That's useless for guidance maneuvering. No significant guidance can occur in 1.2 seconds. 

If the HVP round is an air burst round (there is no indication that an air burst HVP is being actively developed but we’ll speculate for sake of discussion) the HVP fuze can electronically react in 1.2 sec but can the round react, detonate, and disperse an effective burst pattern in 1.2 seconds?  I don’t know. 

The critical question, of course, is what range can a millimeter radar actually detect an incoming missile? Given the extremely small size and low power output of a radar packaged into a sub-5" HVP, I'd guess that 1 mile detection is optimistic but I'm not a radar expert.

-Note that the 5” HVP is saboted and, considering the very narrow shape of the HVP projectile, the “average” projectile diameter is decidedly sub-caliber.  Thus, the room available for packaging an electronic power source, radar sensor/seeker, guidance electronics, guidance mechanics, and fins is very limited.  Any radar seeker will be very small and low powered which means very short detection range.  Trying to fit an explosive and fuzing mechanism into such a small package only compounds the problem.

I’m left wondering about the effectiveness of a HVP (that isn’t really hyper velocity and is only marginally faster than a standard 5” round!) in the AAW role.  The speed is actually a potential drawback for a guided and/or air burst HVP because greater speed minimizes reaction/guidance time.  Counterintuitive, I know, but seemingly true.

We see, then, that the entire HVP concept is factually incorrect – it’s not hyper velocity and is only marginally faster than standard 5” rounds – and conceptually questionable.  The HVP round sacrifices a great deal of size and weight to gain, at best, 23% more speed compared to the slowest 5” standard round and is slower than the fastest 5” standard round.  Do the benefits justify this reduction?  I don’t know but I’m dubious.

The one speed related benefit that I could see is that the extreme aerodynamic shape of the HVP might reduce its drag thereby allowing it to retain more of its speed for a longer period of time.  Again, whether that confers an actual performance benefit is questionable.

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Reference Data:  Speed of sound ~ 760 mph = 1115 ft/sec = Mach 1

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(1)USNI News website, “Updated: Navy Researching Firing Mach 3 Guided Round from Standard Deck Guns”, Sam LaGrone, 1-Jun-2015,

https://news.usni.org/2015/06/01/navy-researching-firing-mach-5-guided-round-from-standard-deck-guns

(2)NavWeaps website,

http://navweaps.com/Weapons/WNUS_5-62_mk45.php

Hyper Velocity Projectile Test

The Navy announced a limited test of hyper velocity projectiles (HVP; for a general discussion, see “Hyper Velocity Projectile”) fired from a 5” gun.  This is great news because the HVP can … can … ah …  Well, I’m not actually sure what the HVP can do.  No one has laid out an actual tactical use/benefit beyond vague generalities, most of which are likely untrue.

Last summer USS Dewey (DDG-105) fired 20 hyper velocity projectiles (HVP) from a standard Mk 45 5-inch deck gun in a quiet experiment that’s set to add new utility to the weapon found on almost every U.S. warship … (1)

Oh, now I see.  The HVP is “set to add new utility”.  That’s good.  We can always use new utility.  What the hell is new utility?

Here’s a bit more specific claim,

… the Navy could turn the more than 40-year-old deck gun design into an effective and low-cost weapon against cruise missiles and larger unmanned aerial vehicles. (1)

I fail to see how a faster projectile is going to transform the AAW-ineffective 5” gun into an effective AAW gun.  It’s still the same 12-15 round per minute rate of fire that’s considered too slow to deal with modern missiles.  It’s still the same train and elevation rates which are considered too slow to deal with modern missiles.  It’s still the same fire control system that is not considered capable of air-to-air gun engagements.

BAE Systems claims all kinds of amazing performance including 40-50 mile range, guidance, 20 rds/min from a 5” gun, high maneuverability, and low cost.(2)  As with any industry touted system, cut the performance in half and double the cost you’ll be somewhere in the real neighborhood.

You’ll recall that one of the original selling points of the rail gun was that it would fire inert, essentially free, projectiles … lumps of metal.  Well the 5” HVP isn’t going to be free.

… a hyper velocity projectile – even in the highest-end estimates have it in the $75,000 to $100,000 range, and that’s for the fanciest version of it with an onboard seeker. (1)

As you know, these kinds of estimates always wind up being understated so figure on doubling that cost.  That’s no longer a cheap projectile.  Yes, it’s cheap compared to a $1M-$2M missile but when you’re firing HVPs at 12-15 rds/min the cost quickly adds up.  At $100,000 per projectile (to use the likely optimistic number cost), firing for one minute will cost $1.2M-$1.5M.  Where’s the cost savings?  Unless the HVP transforms the 5” gun from a 0%, non-AAW-capable gun to something like a 90%, can’t miss weapon, there won’t be any cost savings.

Related thought:  If the HVP is all it takes to turn the 5” gun into a marvel of AAW weaponry, then why are we still wasting money on Standard missiles, ESSM, and RAM/SeaRAM?  But, I digress …

Here’s another suggested use,

HVPs could also find a home aboard the Navy’s Zumwalt-class destroyers as a replacement round for the classes 155mm Advanced Gun System. (1)

The Zumwalt’s 155mm Advanced Gun System (AGS) was intended to be a precision guided, land attack weapon with 70-100 mile range.  How is the HVP going to replicate that performance to be a viable replacement for the cancelled LRLAP?  It could, perhaps, someday, become a second rate, poor man’s replacement but it can’t match the LRLAP specs.  To be fair, the LRLAP couldn’t match the LRLAP’s specs!

What would the cost of a very limited production quantity, one-of-a-kind,  AGS-HVP munition be, do you think?  We’re looking at half a million dollars or more, quite likely!

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(1)USNI News website, “Navy Quietly Fires 20 Hyper Velocity Projectiles Through Destroyer’s Deckgun”, Sam LaGrone, 8-Jan-2019,

https://news.usni.org/2019/01/08/navy-quietly-fires-20-hyper-velocity-projectiles-destroyers-deckgun

(2)BAE Systems website, retrieved 8-Jan-2019,

https://www.baesystems.com/en-us/product/hyper-velocity-projectile-hvp

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)

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.

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,

https://breakingdefense.com/2018/01/86000-5600-mph-hyper-velocity-missile-defense/

(2)BAE Systems website,

https://www.baesystems.com/en-us/product/hyper-velocity-projectile-hvp