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Post by altair4 on Feb 25, 2008 17:30:33 GMT -4
hi
in a sense the Northrop YB49 flying wing is "boomerang" like.I think the Australian Aborigines were on to something and had the "right idea"(aerodynamics)
yeah,interesting point Jay Utah about Pearses's aspirations,anyway there is an interesting collection of his at Auckland Museum of Transport(NZ)
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Post by JayUtah on Feb 25, 2008 17:48:54 GMT -4
The classic angled boomerang has aerodynamic properties very different from the Northrup flying wing. They share only a superficial similarity in shape.
But let's pretend they're roughly aerodynamically equivalent, just for the sake of argument.
The issue is the classic scaling problem in engineering. As you expand the geometrical dimensions of a design, some properties that affect the design don't scale at all, some scale linearly with the dimensions, and some scale as a higher-order function of dimension.
This is why Samuel P. Langley wasn't the first to fly. He had a working powered glider. But the full-sized Aerodrome couldn't fly because Langley wasn't able to scale up the design properly to a full-sized manned vehicle. The weight of the wood increases faster than its strength and stiffness as the principal dimension increases.
So while a boomerang made of solid wood half a meter long and a few millimeters thick might work, a "boomerang" the size of the Northrup aircraft, made of solid wood, would be far too heavy to fly. And while arm strength at centimeter scale is available, commensurate propulsion forces at hundred-meter scale are not.
That's the principal issue behind the notion of a "design limit." We have to use exotic materials, composite construction, and efficient structural systems to achieve in large-scale designs what can be achieved with solid, ordinary materials in a small scale. That's really the fun of engineering.
In the theater world I build sets out of ordinary lumber and carry or roll them with ordinary manual strength. I have stout lads for stagehands. However, I recently toured the set of the Cirque du Soleil show Ka, which has an enormous set piece the same proportions as many of the set platforms I have built. Theirs is made of steel trusses and is manhandled by enormous, well-controlled hydraulics. The hydraulic pumps (four of them) that raise the platform along its 20-meter ascent and descent are each more powerful than the engine in my car. What I do with stock lumber and robust stage hands cannot be accomplished at Cirque du Soleil scale without a complete rethinking of how it is done.
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Post by bazbear on Aug 26, 2008 1:43:32 GMT -4
One of the sexiest designs of it's day (jet or piston engined version), the aerodynamically more trained here can correct me, but one problem was it might start to fly like an actual boomerang at times lol. In the days before computer assisted flight systems it was too much to ask a pilot to handle a flying wing's instabilities.
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Post by Count Zero on Aug 26, 2008 4:14:36 GMT -4
The flying wing did have a yaw-problem. This was it's downfall, since yaw is a Really Bad Thing when you're trying to drop bombs accurately. Northrup eventually improved the control system to deal with it (using analog methods & feedback), but the damage to the plane's reputation was done. It was simply an idea before its time.
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Post by Obviousman on Aug 26, 2008 4:24:25 GMT -4
It is quite funny (IMO) that Northrop had some of the most advanced designs... and some of the most "dated" designs, too!
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