The Mighty Manchester

To be a technical person assigned to a successful project can be pretty wonderful. To see your widget working properly and then going out the door can make you feel like God on the seventh day.

Alas, it doesn’t always work like that. As wonderful as working on a good project can be, working on a bad one can surpass purgatory and proceed directly to hell.

Consider the Manchester bomber.

By the late thirties, with a world war clearly looming ahead, the RAF found itself in a bad position. Its “heavy” bombers, like the Hampden and the Wellington, had been overtaken by the march of aviation and being downgraded to “medium” bombers. With her strategy based solidly on bombing the heck out of Germany, the RAF needed a new generation of “heavy” bombers…fast.

But bomber technology, the ability to lift a heavy load and carry it a long way at a reasonable speed, was critically limited by the engines available. Lots of people were talking about four- engined bombers, but that didn’t look too promising. Adding couple of more (feeble) engines, with their inherent drag and fuel demands promised slow bombers with limited range and speed.

What to do?

Enter the mighty firm of Rolls Royce.

Rolls Royce had a long history of making aero engines. They liked to give their engines names of birds of prey: Eagle, Kestrel, Peregrine, Merlin, etc. The Kestrel was a conventional V-12 engine of a modest 700 horsepower. Adding four of them (with the consequent drag) to a bomber would hardly solve anybody’s problem. But Rolls Royce had an idea.

Suppose, they said, you took two Kestrel V-12 engines and married them together? One would be oriented normally, but the second would be upside down. Bolted together at the crankcase, then both could drive a single crankshaft and Voila! an X-24 engine with 1400 horsepower and only a little more drag than a standard Kestrel engine.

They dubbed it the Vulture and the RAF just loved the idea. They ordered that two of the Vulture engines be included in the big, new bomber that the aircraft company, Avro, was designing: the Manchester. It was to be well-armed, heavy, and state of the art. With extensive hydraulics, powered machine gun turrets, and an enormous bomb bay, it was the main hope of the RAF. Add the powerful, new Vulture engines, and it should be just about perfect.

That’s not the way it worked out.

First, the airframe. When they test flew the new plane, it wandered around the sky. Despite its twin tail fins, it was directionally unstable. The rudders had little control. And put it into a dive and it might never recover. Worse still, its brand new hydraulics had the bad habit of suddenly rupturing and spraying highly flammable fluid all over everything…like the hot engine exhaust manifolds. The plane had also gained a lot of weight in its development, putting quite a strain on those new engines.

And oh, those engines. Mating two Kestrel engines into an X-24 made for an ungodly complicated mess. Each rod bearing had to carry the loads of four (count ’em, four!) pistons. Not too surprisingly, those bearings had a tendency to fail, with the result that the rods poked holes in the side of the engine. Then, too, the engines had a cooling problem, leading to one whole side of the engine being starved of coolant. That also killed the engine. But most catastrophic of all, with such a complicated machine, the lubrication system broke down with alarming frequency, causing the entire engine to seize.

Let’s see now, rod bearing failure. What does that cause? Oh, yes, fire. Overheating engines? Fire, again. Lubrication loss? Fire. And just to add to the crew’s problems, what does spraying hydraulic fluid onto a hot manifold cause? You guessed it.

The story gets darker. The Vulture never developed the power they’d hoped for and each one weighed 500 pounds more than forecast. Add to that there was the fact that the Manchester itself kept gaining weight. The net effect of all this is that when one of the Vultures failed, the other could rarely keep the aircraft aloft. The loss of an engine usually meant the loss of the plane and, far too often, the crew as well..

How bad was it? Well, let me put it this way: aircraft engines aren’t monitored according to the miles they’ve traveled, like a car, but by the number of hours they’ve flown. Military aircraft engines take quite a beating in use, so the number of hours between mandatory overhauls was usually measured in hundreds of hours. At one stage, the Vulture engines had an average of just 79 hours…between complete engine failures!

 And remember, these planes were so desperately needed that they were immediately put into service, wonky airframes and combustive engines and all. The Manchester became a famous crew killer.

Now imagine you were working for Avro. The airplane isn’t stable, so you add a central tail fin. Unfortunately, the upper machine gun turret interferes with the airflow to that new central fin, so you remove the turret. To improve rudder controllability, you lengthen the tail planes so the twin rudders are in quieter air. This works so well you can now remove that extra central fin and replace the upper turret. This adds too much weight, so you keep trying new turret designs. All this does not make for smooth production.

Meanwhile, the hydraulic system is a disaster. A brand new joint design is subject to fatigue and the joints fail unpredictably. You tell the production line to go back to an old design and send teams rushing out to the working airfields to retrofit the operational planes. All the while you are replacing tail sections and turrets with new designs.

This and a hundred other design changes are slowing the production lines and driving the workers crazy. The RAF is screaming (simultaneously) for more production and for all the problems to be fixed. You’ve forgotten what sleep is.

But you’ve got it easy compared to the Rolls Royce people. Not only are their engines failing, they’re failing in balls of flame that destroy the evidence of what went wrong. And like Avro, they not only have to put their fixes into the production line, they have to send teams to the squadrons to retrofit all the changes they’re trying.

It’s human nature to look for the problem. Singular. Imagine you are Rolls Royce. First you think it’s simply a cooling issue, so you change the design to balance the cooling between the banks. Helps, but the engines keep catching fire. Then you find out the oil is getting bubbles in it, creating air locks and stopping lubrication. So you add screen filters to keep the bubbles from coalescing. Helps, but the engines are still burning. You find pieces of rod bearing in the sumps, so you change the bearing material. And change it again. And again. You discover the joint between the upper Kestrel section and the lower is flexing, so you stiffen the joint with pins. Your field workers are working literally 18 hours a day, seven days a week. The air crews have long ago ceased to believe that the latest changes have “fixed” the engines. And engine production is so far behind schedule you can’t see any chance of catching up.

Eventually, the Avro people work out the bugs and the Manchester becomes a stable aircraft with solid reliability. But the same can’t be said for the Vulture. It becomes less flammable and almost dependable, but it remains an ungodly complicated and grossly underpowered monstrosity.

For the RAF, it looks like a tragedy. The Vulture has made the whole Manchester a disaster. Which is a pity, as the Manchester airframe is now so good that it just cries out to be saved. Oddly enough, it is Rolls Royce that comes to the rescue.

While the Vulture team has been drowning in disaster, the Merlin engine team has been going from success to success. Not only had it powered the fighters of the Battle of Britain, it has proved so capable of development that its output keeps going up and up. Pretty soon the Merlin begins to look like the perfect engine to power bombers.

Back at Avro, while struggling to improve the Manchester, they have quietly been working on a revised design with new wings. Four-engined wings. Four Merlin engined wings. Originally called the Manchester III, the dismal Manchester reputation soon leads to the new plane being renamed: it becomes the Lancaster. The Lancaster goes on to become the greatest night bomber of the war. The Vulture goes on…to the scrap heap.

So we can imagine that the Avro teams that struggled with the Manchester airframe bugs would have looked back on their careers with solid satisfaction. They had struggled, but they had won through. But I’ll bet that the poor bustards who worked on the Vulture sometimes woke up in a cold sweat till the end of their days.

I’ve worked on both kinds of projects and oh, ’tis true, ’tis true.

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