Short coupled?
Thread Starter
Joined: Oct 2007
Posts: 107
Likes: 0
From: coventry
Short coupled?
I have at various times been called "short arsed"...that I understand.
However, when an aircraft is described as "short coupled" what couple are they talking about and what particular aircraft characterisitics does it bestow ?
Any information gratefully received,
TIM.
However, when an aircraft is described as "short coupled" what couple are they talking about and what particular aircraft characterisitics does it bestow ?
Any information gratefully received,
TIM.
Joined: Sep 2002
Posts: 2,188
Likes: 6
From: La Belle Province
It usually implies that the stabilizing surface(s) are close to the cg (or wing). I've heard it used in terms of both pitch and yaw.
It means that the surface has to be proportionately larger than if it were not "short coupled". It also means that the interference effects between surfaces will be stronger.
Eurofighter is sometimes called a "short coupled canard delta" which is alluding to the close proximity of canard and mainplane, and the resulting powerful interactions between the two.
F-22 might be called short coupled in pitch too, due to the very close proximity of wing t/e and tailplane l/e.
I don't think there's any particular aircraft characteristic as a result, it's just that the aerodynamics are more interesting.
It means that the surface has to be proportionately larger than if it were not "short coupled". It also means that the interference effects between surfaces will be stronger.
Eurofighter is sometimes called a "short coupled canard delta" which is alluding to the close proximity of canard and mainplane, and the resulting powerful interactions between the two.
F-22 might be called short coupled in pitch too, due to the very close proximity of wing t/e and tailplane l/e.
I don't think there's any particular aircraft characteristic as a result, it's just that the aerodynamics are more interesting.
Joined: Jan 2008
Posts: 127
Likes: 0
From: Wichita, USA
Inertial Coupling...
...can also have some very interesting effects! The NF-104 was a classic example of unpredicted behaviour.
NF104 | Theory to Reality
Up to that point the AST was a typical airplane with static and dynamic stability and a normal proportional rate control system. From there on it became a space vehicle with zero stability and a fixed thrust angular-acceleration control system. In fact, it proved to become somewhat unstable due to cross-coupling of yaw and pitch from the gyroscopic effects of the rapidly rotating jet engine, long after the jet engine was shut down. This had not been predicted.
NF104 | Theory to Reality
Up to that point the AST was a typical airplane with static and dynamic stability and a normal proportional rate control system. From there on it became a space vehicle with zero stability and a fixed thrust angular-acceleration control system. In fact, it proved to become somewhat unstable due to cross-coupling of yaw and pitch from the gyroscopic effects of the rapidly rotating jet engine, long after the jet engine was shut down. This had not been predicted.
