Engines of Our Ingenuity


No. 1583:
GLIDE BOMBS

by John H. Lienhard

Click here for audio of Episode 1583.

Today, the weapon we didn't know about. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Thursday, November 26, 1943. British troopship Rohna is under way from Oran to Port Said in an Allied convoy. She carries two thousand American soldiers. At four-twenty that afternoon, German bombers find the convoy, and they begin circling it.

Troops on the Rohna are puzzled by several smaller airplanes flying below the bombers. Are they allied fighters, there to protect them? Then a couple of those small planes attack the ship ahead of the Rhona. Moments later another comes directly at Rohna. First it falls away from a mother plane, then it accelerates. At 5:30 PM, it strikes the Rohna's port flank at enormous speed.

The device blows open a huge hole, killing hundreds outright. The burning ship sinks, and, when the smoke clears, 1135 troops and crew have died. The images of burned and damaged bodies are a horror that will remain etched on survivors and rescuers alike. One of the least-known weapons of WW-II has just inflicted the greatest American death toll on any ship that went down.

As a pre-teenager, I followed the aerial war closely, yet this is news to me. For the Rohna disaster was hushed up. Its survivors were bundled off to the war in Asia without so much as the chance to grieve. We at home didn't hear about it at all.

What'd struck the ship was something called a glide bomb. Glide bombs had first been used in WW-I. Dirigibles had tried dropping bombs with stubby wings that could glide into the side, rather than the top, of a target.

That idea came back in WW-II. The Germans, Russians, English, Japanese, and Americans all worked on it, but only the Germans and Americans made usable weapons of it. The Germans were first. They realized that such a device had to be radio-controlled, and it needed a rocket booster to get it past enemy fire.

By 1943 the Germans were using glide bombs in combat. The Henschel-293 that destroyed Rohna was a small unmanned airplane with stubby wings and an 1100-pound bomb. Pilot Hans Dochterman dropped it from his Heinkel bomber at about four thousand feet. The rocket kicked in as it fell, and Dochterman's bombardier, Georg Zuther, steered it into the Rohna from a safe distance. It may've been moving over five hundred miles an hour when it struck.

America was developing its own glide bombs by then, and we imposed secrecy on the whole business. Soon after that we'd gained air superiority in Europe, and German glide bombs were no longer a threat. We went on to create our own glide bombs and were soon using them with murderous effect against enemy bridges. By war's end, the Japanese had developed an even more sinister version of the technology. It was the human-flown Kamikaze bomb.

And so the cold waters of the Mediterranean closed over that terrible November day. Rohna went down, and we in America never knew. Secrets had to be kept. And a war had to be won.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)


I am grateful to Robert Mate, University of Houston Chemical Engineering Department, for suggesting the topic, and to Rohna survivor Ralph Allgood for telling me something of what it was like to be there.

Jackson, C., Forgotten Tragedy: The Sinking of HMT Rohna. Annapolis, MD: Naval Institute Press, 1997.

A great deal of good material is available on line; see, e.g.,

http://www.daileyint.com/seawar/seawar11.htm http://www.whidbey.net/rohna/rohna.htm http://vectorsite.tripod.com/avbomb2.html




Luftwaffe photo of a Heinkel He-177. Under the
fuselage rides a Henschel Hs-293 "glide bomb"



The spawn of the German glide bombs: Japan's Kamikaze bomb



The Engines of Our Ingenuity is Copyright © 1988-2000 by John H. Lienhard.