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The Perennial Problem of MTBF, Power-To-Weight Ratios and Mobility vs. Protection return to Haunt APC manufacturers By Julian Nettlefold







03 Oct 19. The old perennial problem of MTBF, Power-To-Weight Ratios and mobility vs. protection return to haunt APC manufacturers worldwide.

In 2010 BATTLESPACE  published a feature on Advanced Armoured Personnel Carrier Designs along with an interview with BAE Systems.  We said that that, in our view,  the current design for APCs had reached its zenith. What was required was new processes to allow for better protection and better mobility to combat the new range of overmatched IEDs and other weapons. If you cannot provide the mobility, you have to keep to the zones and roads where the IED threat is greatest. Thus, you have to increase the protection levels to keep your troops safe from IED and other attacks. What does that do? It brings down the Mean Time Between Failure Rates to unacceptable levels below which troops cannot operate in fast Pursuit Operations, particularly under the new UK Strike Brigade Concept.








But, once disembarked, those troops require better protection on the battlefield with new, weapons and missiles, Infantry Systems,  EO/IR, radios,  body armour and helmet systems which weigh more and take up more space. Result – a bigger, longer vehicle to accommodate your section.








A recent Eastern European Exercise showed the effect of breakdowns on the ability to move fast to protect vulnerable incursion spots.

It also showed another problem. If you add weight to vehicles you need bridges with higher weight-carrying potential, hence a number of new bridging solutions on display at DSEI from GDUKLS and Pearson Engineering and WFEL amongst others.

So, the weight is increased, the MTBF goes up, what happens next? The existing drive train, torsion bar design, suspensions and wheel layout are not man enough to take the extra weight and they break or snap. The Recovery vehicle is called in but, given the extra weight of the vehicle it is servicing it has to be modified, as we saw last week with the BAE Systems contract for M88 Hercules Recovery Vehicle upgrades to accommodate the increased weight of the M1A2 SEP V3 MBT.




The US Future Combat Systems concept in the 1990s, with the UK Tracer/MRAV equivalent failed because the battlefield doctrine then was fight at a distance using long range canon and missiles to engage the enemy. The IED changed all of that. The British Army is in the process of a huge upgrade programme to meet these challenges with Challenger 2 LEP(although not automotive), Warrior and Ajax. To allow these vehicles to engage at distance to defeat the up-armoured enemy vehicles, both Warrior and Ajax required a canon with greater killing potential, CT40 was chosen.

The choice of CT40 over the Bushmaster 44 required new turret designs for Warrior and Ajax. Trials showed that the recoil, 20,000lbs, caused a huge pressure on the turret ring and hull, causing problems for both vehicles. CT40 also required advanced optics and with new Active Protection systems.

Result – beef up your turret structure to make it more robust. Result of this change – more weigh on the suspension and drive train.

Result – breakdowns and more MTBF above that forecast in the bid.




We have a feature in this week’s Update about the US Optionally Manned Fighting Vehicle, Bradley Replacement Programme. Note that BAE Systems has declined to bid. Is this because they know that the current design and technology available for a new APC cannot meet the design and performance criteria without a huge redesign and technology investment which the DoD may be reluctant to pay for?




The previous attempt to replace the Bradley , Ground Combat Vehicle, ended in the cancellation of the Program in 2014, with BATTLESPACE suggesting that the BAE offering, as seen below, looking more like a battleship on tracks than an APC!





In the UK BAE was bitten by liquidated damages from the MoD in its Terrier Engineer Vehicle bid, which resulted in it being very conservative with its Warrior WCSP which Lockheed won. They don’t want to be bitten the same way in the US!

In the UK GDUK is progressing, albeit at a slower than recorded progress, for its Ajax vehicles, with reports of possible  wheel and suspension failures as is Lockheed with WCSP. GDLSUK pitched the ASCOD design to accommodate a larger engine to allow for the growth described above. But, a larger engine puts more strain on the gearbox and the suspension, for obvious reasons as it can travel faster cross-country. The drive systems breakdowns just progress down the drivetrain.

In Spain ASCOD 2, on which the Ajax vehicle is based, is still not in service.


Look at a whole new technology involving more composites and advanced automotive and suspension for the next iteration of vehicles, which will take a decade.

In the meantime accept that higher MTBF and drivetrain failures are the name of the game if you want to protect your troops on today’s battlefield.

What that does to the existing contracts in place where MTBF has been part of the process will no doubt end in disputes with the lawyers always winning!


More Engineer and Recovery Regiments with new Repair and Recovery vehicles and systems and a streamlined Base Repair Process.






It  is interesting to note that the MoD had a bid in its hand to do exactly the above from Dyncorp in its bid for DSG. They would have torn up the existing rule book and built new and advanced service facilities.

But the MoD took the higher more moribund bid from Babcock who claimed an expertise in Through Life Support for the  Royal Navy in particular.


No improvement and drastic reduction in the Land Rover fleet availability in particular.

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