Bede BD-5J

Digital Aircraft Modeler BEDE BD-5J

Reclining in a 358 lb thin walled fuselage with 225 lbs of jet thrust pushing you along at 300 mph. You just can’t get cooler than that. Of course, the safety record may cause you some concern.

How cool is this jet? James Bond cool. It was featured in the 1983 movie Octopussy (I still can’t get over that name – anyone know what it means?) James, being pursued by a heat seeking missile shot by the local bad guys, flies the little jet into a hangar, just barely clearing the closing doors on the other end by doing a knife edge, which might be a little hard to believe if it wasn’t James.

The aircraft was first created in the late 1960’s, and sold as a homebuilt kit in the 1970’s. It was a prop driven plane, pusher style, and it was a hot seller. Not many of the kits that were sold actually got delivered. The company went bankrupt in the 70’s.

As for the safety record I mentioned, the Bede_BD-5 Wilkipedia page tells us there were four early “short wing” versions, all of which crashed on their first flights, killing 3 of the 4 pilots, and the next 21 planes with either the short or the long wings, experienced 10 crashes with 6 more fatalities. That’s 9 dead pilots in the first 24 aircraft! One cause they list is particularly interesting. The high prop location results in a high line of thrust. Think about what is happening when the engine is pushing. The center of gravity is lower than the line of thrust. The more power you apply, the more the tendency to rotate the aircraft so the nose points downward. Not a problem, because you can compensate for it, right? But what happens if the engine suddenly quits? All the compensation you’ve been adding would make the nose suddenly come up high. You’re in a sudden unexpected stall. If you’re close to the ground your one of nine!

We “fixed” this in the model by moving the thrust line down more in line with the center of gravity. It’s easy to do in Digital Aircraft Modeler, and it makes the aircraft a lot friendlier to fly. If you want to fly it more like the original just right click on the “engine” object and select “Engine”. The window you see will let you change the center of thrust. Click the drop down arrow on the “Rotate” gadget so you are looking directly at the right side of the aircraft. Now drag the center of thrust up to the jet engine outlet location. When you fly the model with this high line of thrust you’ll notice the aircraft nosing down when you apply power. The effect is most pronounced at low speeds.

One more thing – we created graphics to make the aircraft look like the one in the movies. I can hear the theme from Octopussy now :)

Download your copy from page 3 of the user’s area.

Good Digital Modeling!
Sunday Flyer Software

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