C2A RUDDER CONFIG
10-09-2007, 08:43 PM
#2
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RE: C2A RUDDER CONFIG
Since it has smaler break angles I think you'll find that it's so that the surface can deflect to a higher AoA before it stalls and creates more drag. In some cases the smoother flow over the deflected surface may well have more lift for a given angle of attack. We'd have to see some lift curves for deflected surfaces to learn more.
10-10-2007, 04:21 AM
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RE: C2A RUDDER CONFIG
Bruce,
Can something like this be modeled in profili?
I have this software but modeling something like that is beyond me
Dave
Can something like this be modeled in profili?
I have this software but modeling something like that is beyond me
Dave
10-10-2007, 06:22 AM
#5
Senior Member
RE: C2A RUDDER CONFIG
Can profili model segmented flaps?
I would imagine that the designer was hoping to keep the flow from detaching at the hinge line and little more. Obviously he'd hope to keep the flow attached for as long as possible, which is why he employed the same hinge design at the original location as well as the additional one.
The one piece rudder deflects and creates a sharp angle at the hinge line. Airflow separates at places like that. Break that angle up into more smaller angles and what happens. Same lift with less drag, or more lift with less drag, or more lift with same drag. Depends on how you measure the results. But they all have less drag.
I would imagine that the designer was hoping to keep the flow from detaching at the hinge line and little more. Obviously he'd hope to keep the flow attached for as long as possible, which is why he employed the same hinge design at the original location as well as the additional one.
The one piece rudder deflects and creates a sharp angle at the hinge line. Airflow separates at places like that. Break that angle up into more smaller angles and what happens. Same lift with less drag, or more lift with less drag, or more lift with same drag. Depends on how you measure the results. But they all have less drag.
10-10-2007, 06:33 AM
#6
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RE: C2A RUDDER CONFIG
Think about it as a comparison of a two plane aero device versus a three plane aero device.
In use, the pilot will stomp enough rudder to get the yaw he wants. He gets that by creating a certain amount of lift out of his yaw creating system. When it's a fin/rudder, a two piece system, how much of an angle will be needed. And where is the airflow apt to separate. At the hingeline. When it's a a hingeline that has to produce a lot of angle, what's the odds it won't create abscission. But when his system is three part, how much angle will be needed at the first hingeline and what're the odds on abscission there.
And if you think about it, the Grumman engineers had some adjusting they could do. They could make the angular change at the first hingeline come more slowly the at the second. For example, if nothing they did could keep abscission from happening before the second hingeline, why not put more crank in the second, it's already stalled. Or not. Just a thought.
In use, the pilot will stomp enough rudder to get the yaw he wants. He gets that by creating a certain amount of lift out of his yaw creating system. When it's a fin/rudder, a two piece system, how much of an angle will be needed. And where is the airflow apt to separate. At the hingeline. When it's a a hingeline that has to produce a lot of angle, what's the odds it won't create abscission. But when his system is three part, how much angle will be needed at the first hingeline and what're the odds on abscission there.
And if you think about it, the Grumman engineers had some adjusting they could do. They could make the angular change at the first hingeline come more slowly the at the second. For example, if nothing they did could keep abscission from happening before the second hingeline, why not put more crank in the second, it's already stalled. Or not. Just a thought.
10-13-2007, 10:52 AM
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RE: C2A RUDDER CONFIG
this is the same type of set up as on the deHavilland Dash 7, Dash-8 and Buffalo.
I am working my way up to building a nice large Dash-8 and/or Buffalo and will be tackling this in the future as well.
If you go to MrAerodesign web site, you will see his design for the Buffalo and
Martin has a linkage worked out for the rudder on that plane.
Dan
I am working my way up to building a nice large Dash-8 and/or Buffalo and will be tackling this in the future as well.
If you go to MrAerodesign web site, you will see his design for the Buffalo and
Martin has a linkage worked out for the rudder on that plane.
Dan
10-13-2007, 11:19 AM
#8
Senior Member
RE: C2A RUDDER CONFIG
The KC-135 uses that boost system on its vertical as a boost tab, not the entire trailing edge.
40 years ago I did a mod for the ACF Electtronics KC1-135 Operational Flight Trainer that added that to the simulator.
It's quite practical, cambering the surface with two segments than the usual single surface.
It develops a higher Cl than a single deflected surface.
I used a boost tab for the flying horizontal on one of my SAE Lifter planes.
40 years ago I did a mod for the ACF Electtronics KC1-135 Operational Flight Trainer that added that to the simulator.
It's quite practical, cambering the surface with two segments than the usual single surface.
It develops a higher Cl than a single deflected surface.
I used a boost tab for the flying horizontal on one of my SAE Lifter planes.
