Author Archives: parvusimperator

More Body Armor Improvements: VTP and TEP

The US Army is always looking for ways to improve on it’s current standard body armor, the IOTV. We’ve already talked about one of the results of this, the Ballistic Combat Shirt. This is part of the Torso and Extremity Protection (TEP) System, and we’ll look at other developments here. We’ll also look at the results of the Vital Torso Protection (VTP) system, an effort to lighten the ceramic plates that stop rifle rounds.

Let’s start with the VTP. The result of this is an eight to fourteen percent1 weight reduction in plate weights, depending on plate size. Plates are available in the standard range of SAPI sizes, in ESAPI and XSAPI equivalent protection levels. Let’s see what this looks like.

PlateVTP Weight (lbs.)
ESAPI Size M5.0
XSAPI Size M5.5

I believe the side plates quoted above are 6″x8″ plates, but I could be wrong. There are a few different side plate sizes.

Now, on to the TEP, starting with the new vest. The new vest is called the Modular Scalable Vest. This vest includes some more clever thinking to reduce weight and improve comfort. One of the things we see on the weight reduction front is the replacement of PALS webbing, which is strips of cordura sewn to the front of the vest to create loops for MOLLE attachments to laser cutting holes directly into the cordura of the vest itself to create loops. Plus, there’s likely some new material in use for the soft armor panels themselves, judging by the weight savings. And those are significant: a medium-size MSV weighs 6.19 lbs. We’ll do a system-level comparison with the old vest, since the new one is smaller, but is expected to be worn with that Ballistic Combat Shirt.

The SPS also includes a new battle belt, called the Load Distribustion System. This is a wide, padded belt that’s MOLLE ready. It also contains some soft armor. It’s designed to allow soldiers to move some things from their vest to their belt to redistribute load from their shoulders to their hips. Good theory, but soldiers being soldiers, they’ll probably just carry more stuff. What isn’t clear to me is if the belt has some kind of system to interface with the vest. Some of the higher end armor makers in the US2 have come up with ways to attach the vest to the belt to redistribute vest weight to the hips too. I don’t know if SPS is going that route. Anyway, medium size LDS weighs 2.3 lbs.

Finally, we come to the Blast Pelvic Protector. This is designed to protect the pelvis and femoral artery from fragmentation injury. It looks kind of like a small pair of chaps, and is worn over the uniform trousers. This is an improvement over the groin protector assembly of the IOTV, as it provides all-around protection. Weight of the BPP is 1.68 lbs.

Okay. Totals time. Again, we’re going to compare system to system, understanding that there are some changes in protected area. And also understanding that I’m not a huge fan of the side plates. But the US Army is, and both vests will have them.

ComponentWeight (lbs.)
MSV, size M6.19
BCS, size M2.89
ESAPI-VTP plates, size M (pair)10.0
ESBI-VTP plates (pair)4.06

Compare this to an IOTV Gen 2 (medium size) weight of 31.79 lbs from the manual, and we have a weight savings of 4.67 lbs. Not bad, SPS program. Not bad at all.

  1. These differences don’t totally agree with my prior weight chart numbers, so I may be missing some versions. Or some of the numbers may be inaccurate. And XSAPI was a guesstimate anyway. 
  2. Offhand, Crye Precision and Tyr Tactical. 

Resurrected Weapons: AGM-129A/B ACM

The AGM-86 Air Launched Cruise Missile was a great way to extend the service life of the B-52. Now, despite the massive Soviet air defense network, SAC’s beloved manned bombers could rain nuclear hellfire down on godless communist scum from over 1,500 nautical miles away. Perfect for keeping big, slow bombers away from fancy air defense systems. And we’ve seen the effectiveness of cruise missiles with conventional warheads many times in Iraq.

But those commies had innovations of their own. They managed to make look-down/shoot-down radars for their advanced fighters, and even had a native AWACS by the 1980s. These could spot the small AGM-86s and shoot them down. One of the key goals of SA-15 was to be able to successfully engage inbound AGM-86s.

You probably guessed the answer to the above problem: stealth. Enter the AGM-129. The Advanced Cruise Missile.1 It had modern, low observability shaping and radar-absorbent material coatings to make it as sneaky as possible. Now it could exploit imperfections in radar deployments, with a vastly reduced detection range allowing it to elude Soviet air defenses. The AGM-129 also had an improved version of the Williams F107 engine that powered the AGM-86. The newer F112 used advanced internal coatings to reduce the thermal signature of the AGM-129. It also brought large improvements in range over the AGM-86’s 1,500 nautical mile reach, though the exact range figure for the ACM remains classified.

The guidance and navigation systems were also improved, but again, remain classified. Russian sources2 give it a CEP3 of 16 meters.

The AGM-129 used the same 5-150 kiloton warhead as used on the AGM-86, the W-80. It was also only marginally longer than the AGM-86, so it could still fit in the bomb bay of a B-52. However, it was about five inches fatter, had a wingspan two feet shorter, and was more than 550 lbs. heavier. And, of course, the stealth coating requires more maintenance. Here was the ultimate standoff weapon for the venerable BUFF, just in time for the end of the Soviet Union. Production numbers were repeatedly slashed, from 2,500, to 1,460, to 1,000, and then to the final total of 460 missiles.

Higher maintenance costs would eventually doom the AGM-129 to withdrawal from service in 2012. Which is a shame, because even if you’re not big into nuclear strikes, a conventional variant4 would be very useful against nations with modern, integrated air defense systems.

Verdict: Funding Approved by the Borgundy Air Ordnance Procurement Board


  1. A very creative name. 
  2. Seriously, they are the only ones that are willing to hazard a guess. 
  3. Circular Error Probable, i.e. the size of a target that the guidance/navigation system has a 50% chance of hitting. 
  4. To the best I am able to determine, no such variant was proposed. From other conventional variants of cruise missiles, we can reckon that replacing the W-80 with high explosives would give an approximately 1,000 lb warhead. 

Resurrected Weapons: FIM-92 RMP Block II Advanced Stinger

The Stinger missile is a hugely successful MANPADS, but it does have cancelled variants, and that’s what we’re going to talk about today. First, a brief discussion of the Stinger.

The FIM-92 Stinger is a man-portable SAM, designed in the late 70s to replace the earlier FIM-43 Redeye. The Stinger is 5 ft. long, 70mm in diameter, and weighs about 34 lbs in its launch tube ready to fire. Unlike Mistral or Starstreak, Stinger is fired from the shoulder, not a tripod.

Stinger has an effective firing range of about 5 miles, due to the nature of its seeker. It uses a dual-spectrum IR and UV seeker. Adding the UV spectrum makes the job of countermeasures designers harder. The countermeasure now has to duplicate the signature of the aircraft across two spectra, not merely the infrared one.

Stinger has been deployed in several conflicts, and has proven effective. It’s easy to use and good at denying aircraft the use of lower altitudes, forcing them out of its engagement envelope.

In addition to use in the man-portable role, the Stinger is deployed on the M1097 Avenger SHORAD system, the Bradley Linebacker, the Stryker-MSL, and as an air-to-air defensive missile aboard Apache helicopters.

And now we come to the RMP Block II program. This integrated the focal plane array IR seeker from the AIM-9X missile onto the Stinger, which brought two key improvements. To understand these, let’s look at what exactly a focal plane array is.

A focal plane array is an array of light (in this case, infrared-spectrum) sensing receptors placed at the focal plane of a lens. It’s also known as a staring sensor, because that’s exactly what it does: it stares. Unlike a more conventional scanning array, it doesn’t build an image from narrow slices rastered across the field of view. Instead, it looks at the entire field of view all the time.

As I said, this brings two major improvements. First, the focal plane array seeker is a lot better at detecting targets than the old dual-wavelength scanning-type seeker, which gave the RMP Block II a larger engagement envelope and longer effective range. The second is a significantly better seeking capability, which translates into both improved performance in cluttered environments and significantly higher resistance to countermeasures. The imaging capabilities of a focal plane array seeker make them extremely difficult to deceive. The RMP Block II would have had good performance against advanced aircraft flying low and firing off decoys, cruise missiles, and UAVs.

The RMP Block II program was cancelled in 2002 for cost reasons. The war on terror was ramping up, and the money was needed elsewhere.

I can understand cost concerns for a MANPADS system if there are other vehicle-borne SHORAD systems available. For the US, there have been a wide variety of recent developments in SHORAD, helpfully linked above. Unlike previous attempts, these are deploying off-the-shelf missiles for the SHORAD role, including the AIM-9X, which has a motor that’s a better ballistic match for the range capabilities of the FPA seeker. The Stinger is already reasonably effective at denying lower altitudes and getting aircraft to fly higher, and low cost encourages wide deployment. I’m inclined to use the money for other things.

Verdict: Funding Denied by the Borgundy War Department Army Ordnance Procurement Board

Engineering Tradeoff Q&A: Puma and Bradley

I finally worked out answers to a few things that puzzled me for a while, and figured it might be fun to post here in a sort of Q&A format. This follows our articles looking at loadouts for the Bradley and Puma IFVs. Having read those articles, you might be wondering the following:

  • How does the Bradley manage to carry so much ammo?
  • The Puma IFV has an unmanned turret, so no turret basket, and it’s pretty large. So why does the Puma only have space for six dismounts?

The space under the turret on the Puma, where we would expect a basket to be on a manned turret, is actually a bunch of storage bins. It takes up about the same amount of space that two more shock-resistant seats would. So that’s where the space goes.

That begs more questions. Why do we need those bins? The Puma requires storage bins under the turret because the Puma’s sponsons contain fuel and various systems. They can’t be used for storage. On the smaller Bradley, the sponsons are empty and open to the cabin. So the space behind the bench seats can be loaded up with tons of stuff for both the vehicle and the dismounts. Check out this picture to see what I mean:

M2A2 storage space

Happily, this picture shows the space being used with things you are probably familiar with, like a cooler and a bunch of 2-liter bottles. In combat conditions, we’d expect this to be full 25 mm ammo boxes and TOW missiles for the Bradley, plus food and ammo for the crew and dismounts. If you give up that storage space, you have to put the stuff somewhere else. And you can’t easily relocate stuff for the dismounts outside of the crew compartment. Hence, storage lockers. Note also in the above picture the floor panels at the bottom left. These can be lifted up to access yet more storage space. This space is normally used to fit 25mm ammo. We can also see some storage space under the bench seat. Convenient, but not the best when dealing with antitank mines.

The Puma uses the in-cabin storage lockers for stuff for the dismounts, and it has a bunch of external compartments to hold the 30mm ammo. The Puma was designed with protection and survivability first. The Germans went to a lot of trouble to put in decoupled running gear to minimize the number of penetrations into the hull for the suspension, since penetrations mean weak points for mines. This meant that the sponsons had to hold more suspension gear. Plus, the Puma’s designers tried to isolate the passengers and crew from the fuel and ammo.

The Bradley was designed in an earlier time when survivability was not as paramount, and its designers put firepower first to counter the expected hordes of Soviet light armor. If the Bradleys could take those out, American tanks would be free to concentrate their fire on enemy tanks. Or so the theory went. While possessing a bit of a glass jaw, the Bradley proved to be an excellent vehicle killer in Desert Storm, and was a good fire support vehicle in Operation Iraqi Freedom.

M2A5 Bradley Proposals

The US Army is continuing to look at options to improve its Bradley fighting vehicles. In the wake of the termination of the Ground Combat Vehicle, the US Army sought a cheaper incremental upgrade process, consisting of two engineering change proposals. ECP1 improved the suspension and tracks, and ECP2 improved power generation and internal networking. For the record, Bradleys that have received both ECP1 and ECP2 are designated M2A4.1

But the US Army is not content to stop there. Further upgrades are being considered, and they consist of a series of proposed changes to both the hull and turret. The final M2A5 will probably consist of some combination of these.

Hull Changes
ECP1 added a reworked suspension to handle more weight. Let’s use that weight. The reworked hull design proposal uses a bunch of design work from the successful AMPV program, which is based on a turretless Bradley. The reworked hull should accommodate more armor and likely some kind of active protection system.2 It’s also somewhat taller than a regular Bradley. The biggest difference is a bit of hull stretch to accommodate an eighth solider. No extra roadwheels will be added. I’m curious about the new seating arrangement.

Turret Changes
This is a little less interesting to me, because these proposals aren’t really anything we haven’t seen before. The conversion from 25x137mm M242 to 30x173mm Mk. 443 is something that’s been trialed before and proposed before. Again, ready capacity decreases from 300 rounds to 180 rounds. Gains include armor piercing growth room,4 ammo commonality with the Stryker Dragoon, and the possibility of using airburst rounds. Not on the docket is any change to the TOW missile launcher. I might have expected Javelin instead, but that doesn’t look to be in the cards.

Alternatively, as ever there are rumors about the US Army investigating foreign made IFVs. I would expect the ASCOD 2 and the Puma to be on the short list of candidates being looked at. Maybe they’ll try to license one. Or maybe not.

  1. Finally. Wish they’d finally designate an M1A3 Abrams… 
  2. The system hasn’t been chosen yet, and it might get integrated into the turret. Or not; the TOW launcher is kind of in the way. 
  3. Or a derivative of the Mk. 44, like the M813 on the Stryker Dragoon. 
  4. 25x137mm Depleted Uranium APFSDS is roughly equivalent to 30x173mm APFSDS, so some well-made DU rounds should give yet more punch to the 30x173mm. 

EXTRA: Trouble at SilencerCo?

We interrupt our regularly scheduled posting to bring you this Extra Edition. Today we’re going to get business-y and talk a little bit about problems at SilencerCo. As you may have gathered if you don’t already know, they make suppressors.

A lot of this is speculation, because SilencerCo is not publicly traded, so there are no financial statements to read. But here’s what we know:

  • They haven’t had a big, mass-appeal product for a while now. The last one I recall was the Omega.
  • Their most recent product launches are pretty niche market. One of them, the Maxim 9 integrally suppressed pistol, was definitely an R&D-heavy project.
  • Between people waiting to receive silencers that they panic-bought during the Obama administration and people waiting to hear a decisive yes/no vote on the Hearing Protection Act, the silencer market is pretty down right now.
  • SilencerCo has had a rocky relationship with Silencer Shop lately, and Silencer Shop is one of the biggest silencer retailers in the US, and certainly among the easiest to buy from.

All of the above combine to really hurt cash-flow. They desperately need a rebound product and marketing help, both of which require money. SilencerCo has been going through a few rounds of layoffs. Which might just be reorganization.

Currently, there are rumors floating around that the top three executives have been voted out by the creditors at a shareholders’ meeting. And that is starting to get troublesome. It definitely looks like trouble is coming to a head over in West Valley City.

I hope SilencerCo can pull it out, but it doesn’t look good. We’ll see how it turns out.

What’s In a Bradley?

Let’s take a look at what’s in a Bradley, courtesy of Hunnicut’s excellent work on the vehicle. Some of the information below is a little old (it’s from back when the M60 was the US Army’s squad support weapon), so I’ll make estimates for more modern systems as appropriate.

–Equipment for Vehicle Subsystems–

  • Fuel: 175 gal.
  • Engine oil: 26 qt.
  • Ready 25mm rounds: 300
  • Stowed 25mm rounds: 600
  • Ready 7.62mm rounds: 800
  • Stowed 7.62mm rounds: 1,4001
  • Ready TOW missiles: 2 missiles
  • Stowed TOW missiles: 5 missiles (Or 3 TOW missiles + 2 Javelin missiles, see below)

–Equipment for Dismounts–

  • Stowed 7.62mm rounds: 2,2002
  • Stowed 5.56mm rounds: 5,3203
  • Stowed AT4 Rockets: 3 rockets
  • Stowed ATGMs: 0 or 2 Javelin missiles

Curiously, in the tables in Hunnicutt’s book, both AT4 and M72 LAWs are listed as carried. In the text he mentions that AT4s were carried instead of LAWs and stowage was altered accordingly. I’ve gone with the latter here. We can also see that the Bradley is absolutely loaded with ammo.

  1. In Hunnicut’s table, ammo for the coax M240C is noted separately from the ammo for the M60 that’s to be deployed with the squad. I have preserved the distinction here (See also note 2) 
  2. These might also be used in the coax gun, since they’re still linked 7.62x51mm. Alternatively, this space should hold about 3,300 rounds of 5.56mm belted ammo for M249s, which is the current squad automatic weapon of the US Army. 
  3. Originally these were separated out for the M239 Firing port weapon and the infantry’s M16s, but the M239s didn’t work very well, and later versions of the Bradley plated over the firing ports. In any case, the M16 and M239 use the same magazines, so I haven’t split the ammo out here like Hunicutt does. 

What Does a Puma Carry?

Here’s a list of stuff that a Puma carries, at least according to Tankograd’s wonderfully photo-laden book on the vehicle.

–Equipment for Vehicle Subsystems–

  • Fuel: 900 L
  • Ready 30mm ammo: 200 rounds
  • Stowed 30mm ammo: 161 rounds (in seven-round boxes)
  • Ready 5.56mm ammo: 1,000 rounds
  • Stowed 5.56mm ammo: 1,000 rounds
  • Ready ATGM: 2 missiles
  • Stowed ATGM: 0 missiles
  • Grenade Launcher, Ready Rounds: 12 76mm Grenades -OR- 24 40mm grenades

–Equipment for Dismounts–

  • Stowed 5.56mm ammo for dismounts: 1,500 rounds
  • Stowed 40mm grenades: 36 rounds
  • Stowed frag grenades: 30 grenades
  • Stowed smoke grenades: 7 grenades
  • Stowed signal rounds: 20 rounds
  • Stowed rockets: 4 Panzerfaust 3 rockets and 2 launchers
  • Stowed Water, 1.5 L bottles: 32 bottles

The Tankograd volume doesn’t make mention of how much of the 5.56mm ammo stowed for the dismounts is in magazines and how much is linked for the dismounts’ MG4. 1,500 rounds doesn’t seem like all that much for six men, but perhaps the Germans trust their supply. It’s nice that Tankograd notes how much water the Puma usually carries.

Resurrected Weapons: XM307

Here’s yet another attempt to replace the Mk. 19 GPMG and/or the venerable M2 HMG. The XM307 was part of the same program that gave us the XM29 OICW, and later the XM25 once the OICW failed. The program itself emerged from a 1980s study saying that weapons development had reached a plateau, and that the next breakthrough would come with the integration of airburst-fused high explosives into the US Army’s weapons. They had tried to schedule a breakthrough in the late 1960s with SPIW. They failed. Now, a new generation of engineers would try their hand.

The XM307, or Advanced Crew Served Weapon (ACSW), had the same airburst principles as the XM25 and XM29. The gunner would use an integrated fire control system to get the range to target with a laser rangefinder, set an airburst distance, and then shoot rounds at the target. Except now with automatic fire. Let’s look at a quick size comparison chart:

XM307M2Mk. 19
barrel length25.1″45.0″16.25″
weight50 lbs.83.78 lbs.77.6 lbs.

It’s definitely lighter. Plus, it’ll bring a flatter trajectory than the 40mm grenades of the Mk. 19, so it should be easier to score hits with. Those are pluses. And, the M2 doesn’t pack an explosive punch. All good things so far for the XM307. So let’s talk lethality.

From autocannons, we know that autocannon ammunition makers don’t think a 25mm autocannon shell holds enough explosives to make an airburst fuse option worthwhile. We know there are lots of deployed 25mm systems, so there’s plenty of incentive to try. Big market, but nobody’s bothered. This isn’t a perfect comparison, of course. Sizes may vary, but if there’s a difference, the autocannon has the bigger projectile. A 40mm Bofors fires a much bigger round than the 40mm Mk. 19. Still, it’s cause for concern.

More concern comes from the test deployment of the XM25. In Afghanistan, while there are plenty of accounts of airburst rounds scaring Taliban fighters away, there are no accounts of it actually killing anyone. And this should be its best chance for success: taliban fighters don’t wear any kind of protective gear. None. If it can’t get kills there, what about when it encounters troops wearing actual modern armor? At least the Mk. 19 has a long history of being effective against unarmored opponents. It starts somewhere. Also note that lots of comparisons with 40mm grenades make a comparison between 25mm Airburst HE-Frag and 40mm HEDP, which is going to be less effective in the pure-antipersonnel role than 40mm HE/HE-Frag.

Now, the XM307 has automatic fire capability, and a belt feed, unlike the XM25. We’re not limited to a one round for one round comparison, which means we’re going to get into “stowed kills” type computations. Clearly, the XM307 holds more grenades in a box than the Mk. 19, so we can try to come up with some notion of relative effectiveness. Or we could, if we had a lot of ammo and a proving ground. Unfortunately I don’t, and I don’t know if the US Army tried this computation. The XM307 was cancelled in 2007.

Another obvious option is to integrate the airburst fusing and targeting system into existing 40x53mm grenade systems. So you’d still have the option of using existing grenades that work, plus you wouldn’t have to develop an entirely new round and ammo system. Someone at DoD actually thought of this, and the Mk. 47 was born. It’s lighter than the Mk. 19, fires the same 40x53mm grenades, and is equipped with a targeting system to set the fuses of airburst grenades. In US Service, that would be the Mk. 285. It’s in limited use in the US Military, and has seen export success with Israel and Australia. So let’s go with that, because it’s way less cost and risk.

Verdict: Funding Denied by the Borgundy War Department Ordnance Procurement Board