XM157 Drake – the Giant DUKW

The DUKW is one of the most famous trucks of the Second World War, but many do not know about the family of trucks that followed it. The biggest was the XM157 Drake, a monstrously large 8×8 truck that could carry the equivalent of a DUKW as cargo.

It had two engines, two gearboxes, a massive cargo bed, and was more maneuverable and faster than the original DUKW. So why is this incredible vehicle virtually unknown today?


Origins in the Duck

The DUKW is a well-known Second World War vehicle, but it is often misunderstood just how influential this seemingly niche truck actually was. The DUKW had originally been designed and pressed into service in very short order, with the expectation that it would only need to work until the end of the war. However, it continued to have a heavy influence on amphibious vehicles decades after its creation.

The DUKW’s designers had inadvertently created an exceptionally versatile machine that became invaluable to the Allies. An amphibious truck like the DUKW provides several logistical benefits, especially in the 1940s.

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At this time, helicopters were not yet available to deliver supplies straight to bases, and cargo aircraft were usually only capable of arriving in rear areas. Therefore, ships and trucks were the primary way of keeping an army supplied.

A DUKW off the coast of Iwo Jima.
A DUKW off the coast of Iwo Jima.

Typically, a ship would arrive at a port and offload its cargo, which would then be loaded onto trucks and transported to its destination. This is perfectly acceptable when there is access to a port, but war doesn’t always afford that luxury – especially during an invasion.

To work around this limitation, flat-bottom ships and landing craft could land directly on beaches without the need for port facilities. However, the cargo still needs to be offloaded onto trucks. The DUKW was a solution to this inefficiency: it could make its way from ships off the coast directly onto shore, and continue inland without needing to stop and offload.

It was based on the GMC AFKWX, the cab-over version of the famous CCKW 6×6 cargo truck. Surrounding this chassis was a light, boat-shaped hull that included a propeller at the rear and a rudder for movement in water. Just behind the bow was an open cab, and behind that was a cargo bed.

DUKW on Okinawa.
DUKW loaded with supplies on Okinawa, 1945.

Up to 5,175 lbs of cargo could be loaded in the cargo bed, or 25 troops. Weighing 20,000 lbs all in, the DUKW could motor through the water from a mother vessel directly to shore, drive onto the beach, and continue inland.

This exact ability was invaluable on D-Day, when DUKWs loaded with men and equipment made their way onto the beaches of Normandy, keeping the invasion supplied as it moved inland. However, its designers had created a vehicle that had virtually limitless uses.

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Its seaworthiness was good enough that it could be used as a near-coast search and rescue machine, or to transport high-ranking officials to and from ships on the coast. But as the war moved deeper into Europe and further away from the sea, the use of the DUKW did not decline. It proved exceptionally useful in river crossing operations, ferrying men and supplies across them, or keeping forces on the other side supplied without the need for a bridge.

DUKW and ship.
A DUKW after being loaded by a merchant ship.

But while the DUKW was a revolutionary design, it was not perfect. It only had a top speed of 6 mph in water, and its open cab was not ideal for marine operations. In addition, the DUKW’s 6×6 drive train struggled with traction while moving from water onto land. On beaches, it performed adequately, but on steeper slopes, like river banks, it could sometimes prove impossible. But most crucially, its cargo capacity was simply too small.

After the Second World War, the US began a project to improve on these limitations. This wouldn’t be done by one vehicle though, but by a family of amphibious trucks, each designed for different circumstances. Interestingly, this idea would result in the monstrous LARC series of amphibious vehicles that served into the 2000s.

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The best-known of the truck types is the XM147 Super Duck, based on the newer M135 cargo truck. It was faster and nearly doubled the cargo capacity, but limitations (including struggling to move onto land) in the design meant it was not built in large numbers.

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The biggest of the lot was the XM157 Drake, a huge 8×8 truck with a boat-shaped hull that resembled a massively scaled-up DUKW. The XM157 Drake was intended to solve the issues of cargo capacity and difficulty leaving the water.

The XM157 Drake.
The XM157 Drake.

XM157 Drake

Development of the Drake began in the first half of the 1950s after it was realized that even the XM147 Super Duck also suffered from poor traction while exiting water onto land. Therefore an 8×8 was needed, which would give the truck better traction during this phase.

The vehicle was ordered by the Ordnance Tank-Automotive Command, and was designed and built by General Motors Corporation.

It was a very large machine, much larger than the original DUKW and the XM147 Super Duck, with a cargo capacity more in line with landing craft than its siblings. It was so big it could carry a 7.2 meter long, 22,000 lb M51 dump truck in the back.

The XM157 Drake.
The XM157 Drake was 11 ft longer than the original DUKW.

The most obvious addition is a fourth axle, located at the front under the cab. This was important to improve weight distribution and spread the load across a greater area for the water-to-land transition.

Powering the Drake were two 302 cu in (4.9 litre) GMC Model 302 6-cylinder petrol engines that produced 155 each. Instead of the engines sharing a common output, like the GM 6046 twin diesel, each of the Drake’s engines powered one front and one rear axle.

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The engines ran independently and were connected to their own torque converter six-speed gearboxes. They also sent power to two propellers at the rear of the Drake. The propellers provided the propulsion in water and steered the vehicle by swiveling.

XM157 propellers.
The trainable propellers at the rear.

When on land, they could be raised so they wouldn’t catch on the ground or obstacles. The Drake was also novel for its use of adjustable air suspension. This made it possible to control the ride height of the vehicle and partially retract the wheels could to reduce drag when in water.

Steering was achieved by all four front wheels, and this was made easier for the driver by a power steering system. The Drake was built from a large space frame hull, rather than a ladder frame found on the DUKW. This increased strength and reduced weight.

The frame was wrapped in an aluminium, watertight hull shaped to optimize its efficiency through the water. A wave deflector was situated on the bow.

XM157 Drake air suspension,
Close-up view of the Drake’s air suspension.

It had the same layout as the DUKW, with the cab set behind the bow, and a cargo bed behind behind that. Unlike the DUKW though the Drake’s cab was enclosed – a change that was probably appreciated by anyone who operated it.

The cargo bed is where the Drake’s enormous size pays off. The bed was 23 ft long and almost 9 ft wide – nearly double the length of the DUKW’s 12 ft 4-inch long bed. Ribs arched over the cargo area for a canvas cover, if needed.

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The huge bed naturally provided a massive increase in cargo capacity: 16,000 lb! For comparison, the DUKW maxed out at 5,175 lbs. It seems the Drake’s actual maximum load was a significant amount more though, as some sources mention a maximum of 20,000 lbs, and a photo shows a 22,000 lb truck in its bed.

M51 in Drake.
Yes you are seeing that right – that is a 22,000 lb M51 truck in the back of a Drake.

It also slightly improved on the DUKW’s 6 mph top speed in water with a maximum of 9 mph. It was slower on land though, with a top speed of 44 mph versus the DUKW’s 50 mph – although this isn’t bad considering the size difference.

To further improve the Drake’s ability to move onto land from water, or for use in poor road conditions, a central tire pressure inflation system was fitted. The DUKW was the first truck to have this feature, and the Drake inherited that trait.

Another new addition to the design was a tailgate – the DUKW lacked this useful feature, so heavier pieces of cargo had to be craned out. The Soviet copy of the DUKW, the BAF 485, had a tailgate, and so did the Drake.

The DUKW, Drake, and Super Duck in one shot.
A fantastic shot of the amphibious truck line up. The original DUKW is on the right. The XM147 Super Duck is in the middle, and the huge XM157 Drake is on the left.

All in the Drake was a huge machine. It measured 42 ft in length and 10 ft in width, with a total empty weight of 28,700 lbs. When fully stocked with fuel, engine fluids, a driver and a full cargo load, the Drake reached a staggering 48,000 lbs. This is around the same weight as a Panzer IV tank.

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Testing and Cancellation

The Drake showed good handling during tests. It was a whole different beast to the DUKW and Super Duck but surprisingly was more capable than them both in most ways.

This was especially true on land, where its additional axle and air suspension gave better traction and a smoother, more stable ride. The driver’s job was easier too, as he was provided with power steering.

In the water, the Drake was faster and more maneuverable than the DUKW and Super Duck, all while carrying significantly heavier loads. This was likely due to the directional thrusters at the rear and more powerful powerplants. It could also handle very rough surf and was impressively seaworthy.

XM157 leaving the water.
XM157 Drake leaving the water.

The vehicle showed some directional instability in the water, but in general, it was a very capable machine that could shift large loads from ship, to shore and beyond. Despite that, only two Drake prototypes were built, and the design would never enter service.

Why? Well, complexity and reliability are the primary reasons.

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The Drake was a powerful piece of equipment, but it was also very complicated. It had a central tire inflation system, adjustable air suspension, two engines, two gearboxes, two propellers, and power steering, just to name a few.

All of these systems added points of failure, and the technology of the day meant reliability was less than desirable. One example of this was the differential bearings, which were too weak for such a machine and caused several breakdowns.

Driver's position in the cab.
Driver’s position in the cab.

To make matters worse, the Drake was not “mechanic friendly” – a nice way of saying that it was a nightmare to work on. Its design did not adequately incorporate accessibility and ease of maintenance, so when things did break they were hard to repair.

For example, the entire cab to be removed to access the engines. These factors, combined with its cost, and the fact that the Super Duck could do much of the same job for less, meant the Drake was not brought into service.

So what happened to the trucks? We currently are unable to confirm the location or fates of the two Drake prototypes. The only lead we have is a collection of photographs from the 1980s that show one of the prototypes at Silverstein’s army surplus yard in Detroit in the US.

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This proves at least one was kept into the 1980s and thus was important to someone, but its current whereabouts are unknown.