Anonymous
Anonymous asked in 科學及數學其他 - 科學 · 1 decade ago

# 設計建造以浮力升空再以噴射引擎推進滑翔飛行大型飛機是否可行

Update:

(1) Is it possible to design the airccraft not in a traditional way, make the aircraft more like a Flying Saucer, or similar design, but still can fly with the jet- engine. Therefore, no need to design the aircraft with a large wingspan, to reduce the large opposite air drag from the wingspan.

Update 2:

(2) Is it possible to make the air-sac elastic and folding?

(3) If the aircraft can vertical take off and landing by the air ballon effect, is it more safe and less land using for the air-port.

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• 1 decade ago
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技術上是否可行?

Technically it is possible, what you are referring is actually a modern air-ship. Combine with hot air ballon technology.

However, there is a problem.

The question on the wingspan (You would still need wing cos you are plainning on using Jet engine.) is you need a relative large wingspan to creat enough gliding effect for the craft to travel, unless your wing can retract all the way inside the craft, otherwise your wing will produce a draft to opposite the lift breated by the hot air ballon effect. The larger the wing are, the larger the draft is. And is harder for thecrast to lift or desent.

可伸縮之氣囊與飛機之比例要有多大,才有足夠浮力將飛機垂直升降?

Theratio would be big, it would be about 1:20 - 1:30, that mean the Air sac would be 20 to 30 times bigger than the cabin

假如可行,飛機能否建造得較大,能否合符經濟效益?

I would not see how it would be more effective doing thing this way.

First,you still using the jet engine most of the time except for take off and land. Which you need to understand is a very short period of the overall flight.

Second, you need more thrust for your craft as you don't just propell the cabin, but all the stuff you need together, as far as i make out, you have aLarger wing, cabin, air sac, proplusion system...

It would be the larger the craft is, the larger effective gap between conventional jet aircraft.As there are a larger weight for the engine to pull mid-flight.

It is a good idea but should not be enough for modern aviation or airtransport aviation. It would be suitable for leisure cruise or some sort.

2009-11-26 08:05:07 補充：

1.) Yes, but it would involve flight electronic and fluid mechanic, the built price will be way more expensive than normal jet aircraft. (Notice a B-2 Bomber with unconventional fuselage cost US\$2 billions each aircraft a Boeing 747-400 cost 100 millions (20 times less)

2009-11-26 08:10:29 補充：

2.) Yeah, but, when would be the apporiate time to fold it i wonder? If you fold it Before you start your jet engine, you will freefall. If you fold it after you start the jet engine, you may tear it up if the sac was only made from elastic but no metal frame.

2009-11-26 08:12:16 補充：

3.) Actually it wasn't, if you use hotair ballon effect to land an airship, cross wind would become a very major factor on landing. Small breeze wind will blow you off landing zone, strong breeze will topple your airship over and crash.

Source(s): My brother is an flight engineer working for boeing
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