DSflyer05

Now Im not quite sure but I would bet with all the drag and the thrust to weight ratio, you would get more of a greater yawing factor on your kingair as compaired to loosing one on a 747. I would just think all that weight would help you stabalize. Plus with 4 engines you "basically" loose 1/4 of your thrust as compaired to 1/2 of your thrust on a twin. Thats just my idea though. I dont have any experience on either of those airplanes.

Senior Skipper

Cubdriver, I'll take a stab in the dark and say you studied aeronautical engineering. Am I right?

SmoothOnTop

Fundamentals of Flight? 80 bucks?

Cubbie,

Before you and I existed, engineers developed (theory) formulae for lift and drag.

Depending on the quality of your college texts, you may find how engineers were able to approximate * lift based on the strength of finite wing span flow turning vortices.

To your question regarding an infinite span, let's assume a constant chord:

Do you think we'd find a vortex?

* derived from experiment and observation rather than theory (empirical).

Cubdriver

Aerodynamic theory has its origins in hydrodynamics developed to make better ships centuries ago. Most of hydrodynamics applies to aerodynamics and served as a good starting point. Air is compressible above M=.3 but it did not matter in the early days because nothing went more than about 25 mph.

Theory and practice went along parallel lines historically. The Wright Brothers pushed it along experimentally, Otto Lilienthal before them and many others contributed to the body of knowledge to make it the bonanza it is today.

As far as whether early experimenters were able arrive at estimates of lift without fully developed theory, I am sure they were but it was time consuming, dangerous, slow, and expensive. Otto Lilienthal died in one of his own experiments. Ideally theory and experiment go hand in hand. Often someone will intuit a principle while theory only follows later and sometimes not even from them. It can also go the other way and theory can drive a discovery as well. For example, Buseman and RT Jones both theorized the benefit of wing sweep in the early 1930's but the benefit wasn't realized until the age of jets after WWII.

As far as infinite wings are concerned, all you have to do is put plates at the ends of wings in a wind tunnel to simulate an infinite wing. The wind itself tunnel can be the ends of the wing also. You will not find vortex rolls like those seen in real life aircraft. However, all the theory involving vortices still applies. The idea of vortices in lift is far more than just those wingtip rolls you refer to. It forms the basis for all modern theory of lift in the low-speed realm.

Skipper- yes I studied aeronautical engineering and have the t-shirt to prove it .

SmoothOnTop

ah, we disagree..

to me, it's 'cause' and 'effect'...

SabreDriver

Having flown both the KingAir and the 747 Classic, I'll take your bet, you'd lose.

If you snuff an outboard on the Whale at lower speeds (say below 100 Kts), there is a good chance you're going in the dirt, unless you are really quick to pull the other 3 back. The problem is the huge fan on the opposite wing that is still making >50,000# of thrust, there is just not enough rudder/nosewheel authority at slower speeds. After V1 it is almost a non event unless you are heavy, say above 800,000# on a hot humid day with a 3000' pressure alt, then it is a real sporting event

IFlyEm

Exactly. I had #1 go at 60 or 70 knots. As soon as the FE called "Power Set" the sim instructor seized #1. Let me tell ya. That is EXCITING!

Gillegan

An excellent answer but I have to take some exception to point. 6. In fact, putting the engine further outboard, while putting more bending moment on the wing root when at rest, when in flight, actually reduces the bending moment due to lift. My understanding (though this could be wrong) is that the effects of the flight case are greater, thereby allowing a reduction in structural weight of the wing with the engines on the wing.

Cubdriver

True. Wing stations near the engine have lower lift characteristics especially in slow flight when flaps and slats are required. The lift curve of the wing is less affected with an outboard engine placement than inboard. The wing does not need to be as strong if the lift loads are located closer to the root and the engine is farther outboard.

joepilot

Gillegan,

I think that I have to disagree with your conclusions. The worst case structural scenario is a hard landing with lots of wing fuel and engines mounted far out on the wings. I think a search of the FAA accident database will show a much greater percentage of jet transport wings that fail downward in a hard landing than have ever failed upward (in jet transport aircraft). Of course, at least if the wing fails downward in a hard landing you have a chance of getting out, whereas if it fails upward in flight you are in serious trouble.