Less Is More — Or How To Replace a $25,000 Bomb Sight for 20 Cents [Hackaday]

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Depending on who you ask, the Norden bombsight was either the highest of high tech during World War II, or an overhyped failure that provided jobs and money for government contractors. Either way, it was super top secret in its day. It was also expensive. They cost about $25,000 each and the whole program came in at well over a billion dollars. The security was over the top. When not flying, the bombsight was removed from the plane and locked in a vault. There was a pyro device that would self-destruct the unit if it were in danger of being captured. So why did one of the most famous missions of World War II fly with the Norden replaced by 20 cents worth of machined metal? Good question.

You often hear the expression “less is more” and, in this case, it is an accurate idea. I frequently say, though, that “just enough is more.” In this case, though, less was actually just enough. There were three reasons that one famous mission in the Pacific theater didn’t fly the Norden. It all had to do with morale, technology, and secrecy.

The Mission

Sometimes, appearances matter. If you ever test a user’s reaction to waiting for output, you will find that they are more tolerant of watching a screen of data scroll by slowly than they are of waiting less time for the data to appear suddenly out of nowhere. Doolittle’s raid on Japan was like that. It wasn’t really practical and was unlikely to change the outcome of the war, but it made people feel like something was being done.

After the attack on Pearl Harbor, the United States was seriously upset. Even though Hawaii wasn’t part of the mainland, it was part of the country and Americans keenly felt the threat that Japan could strike American soil. America needed to strike back but had few options. Much of the navy was out of commission because of the attack. The planes of the era couldn’t cross the Pacific loaded with bombs and fuel. The Americans had no missiles that could make the trip, either.

Enter Jimmy Doolittle. Where nearly everyone else thought there was no way to retaliate, Doolittle and a few others were convinced he could find a way. He formed a squadron of B-25 Mitchell Bombers and set out to prepare them for the trip to Japan.

Less… Much Less

The B-25 had a normal range of 1,300 miles, but it needed to go at least 2,400 from an aircraft carrier to hit Japan. Everything had to go to lighten the planes and make room for additional fuel tanks.  Guns, blast plates, cold-weather equipment, and some radios had to go.

New fuel tanks took up some of the space created. One other thing that had to go was the Norden bombsight. It wasn’t good for low altitude bombing was the official story. However, the weight was also significant and — perhaps the main reason — it seemed possible that at least one of the planes might be shot down and captured. The Army Air Corps did not want to risk the Norden. Turns out, the Germans got the plans delivered to them before the war and had their own version of it, but no one knew that at the time.

But You Still Need a Sight

Photo by [Pi3.124] CC BY-SA 4.0

However, you still need some kind of bombsight. That’s where Charles Ross Greening with some machining help created what he called the “Mark Twain” bombsight. The newspapers would later call it the “twenty-cent bombsight” because of the few materials it used. Here’s a description from Wikipedia:

[The Mark Twain] consisted of a quadrangle measuring 7 inches (18 cm) by 7 inches (18 cm), inscribed with a 90° arc in 10° increments, and placed horizontally on the Norden mount. When the quadrangle was turned left or right, a handle deflected the Pilot direction indicator, indicating the prescribed heading for the pilot. A vertical piece, measuring 5.25 inches (13.3 cm) by 7.25 inches (18.4 cm), set the dropping angle, based on bomb size, altitude, wind conditions, and ground speed. The vertical piece had a sighting bar with a “V” notch at the rear, which was to be aligned with a point at the front, just as in a rifle sight. The bombardier aimed the bombsight in the direction of the target, raising the tail as he got closer, until he reached the dropping angle, when he would release the bombs.

Simplicity, itself. Yet less is more. It is possible that the cheap sight may have worked better than the Norden’s actual performance, at least in some cases. The raid was sort of a success. It didn’t manage to do much real damage and all the planes were ditched, but it had a positive effect on Allied morale and the opposite effect on the Japanese population.

Lessons Learned

There’s a famous old story that NASA spent money to build the space pen and the Russians simply used pencils. Turns out that the story isn’t true (NASA didn’t pay to develop the Fisher space pen). But it reminds me of the 20 cent bombsight. While you can cut too far, sometimes less really is more.

I think we forget this too often. We often hear of relatively simple systems failing due to having too much software layered on top of them unnecessarily. For example, check out EDN’s report on the infamous Toyota firmware problems. Granted, this could be a case of poor workmanship more than over-complication, but then again, I’d rather have a handful of dedicated CPUs doing very specific tasks on bare metal than some big processor with an RTOS handling so many life-critical tasks.

If you want to know more about the hype around the Norden, we talked about it before. We’ve also talked about the era’s heavy bombers, too.

Headline photo: Norden Bombsight at Computer History Museum by Allan J. Cronin, CC BY-SA 3.0