Spoilers
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Joined: Nov 2000
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From: Scandiland
Spoilers
Hi all!
I'm writing an extended essay about wing construction. The essay is actually not the main part, it's mainly a comment on the modell wing I'm building. The wing is designed much like a fullsize wing incorporating a moveable slat, fowler flap and a spoiler. However, the last of the three has caused me some problems. Where do I put it? Someone told me that it should be placed where the centre of pressure acts from. With a flap in the up position this will be somewhere on the middle or where the wing is thickest. However, when the flap is fully extended, the centre of pressure will wander rearwards. Is this correct? Is it then feasable to place the spoiler on the slot lip of the wing (the part of the wing that extends over the fowler flap)?
A spoiler that is placed over the centre of the wing will however disrupt the flow over a greater distance of the wing and therby more lift. Which is correct? I guess it depends on the intended use of the spoiler.
What I want to know is if there is any sense at all in placing the spoiler on the rearmost part of the wing.
regards/lns
I'm writing an extended essay about wing construction. The essay is actually not the main part, it's mainly a comment on the modell wing I'm building. The wing is designed much like a fullsize wing incorporating a moveable slat, fowler flap and a spoiler. However, the last of the three has caused me some problems. Where do I put it? Someone told me that it should be placed where the centre of pressure acts from. With a flap in the up position this will be somewhere on the middle or where the wing is thickest. However, when the flap is fully extended, the centre of pressure will wander rearwards. Is this correct? Is it then feasable to place the spoiler on the slot lip of the wing (the part of the wing that extends over the fowler flap)?
A spoiler that is placed over the centre of the wing will however disrupt the flow over a greater distance of the wing and therby more lift. Which is correct? I guess it depends on the intended use of the spoiler.
What I want to know is if there is any sense at all in placing the spoiler on the rearmost part of the wing.
regards/lns
Joined: Jun 2001
Posts: 135
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From: Brisbane
It should logically follow that the point of an aerofoil which produces the most amount of lift (indeed the point at which the Centre of Pressure is located) is coincident with the point of greatest Camber. From my knowledge usually located somewhere in the first third of the aerofoil, behind the leading edge.
Putting a spoiler anywhere else would still provide a means of dumping lift and increasing drag, but it would be far more effevtive to put one (or many) at the point of greatest Camber.
Putting a spoiler anywhere else would still provide a means of dumping lift and increasing drag, but it would be far more effevtive to put one (or many) at the point of greatest Camber.
Thread Starter
Joined: Nov 2000
Posts: 480
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From: Scandiland
Cheers SW.
Depends on where you are... Stockholm is really nice during the summer months but it gets really grey and horrible during winter. The Great North is quite nice during both seasons but everything is alot slower up there. Dunno why really but it's like the Twighlight zone all the time...
My conclusion for the time being is that a spoiler intended to depleat speed only should be at the rear. This should have the effect of not destroying so much lift, simply creating huge amounts of formdrag.
A liftdumper or ground spoiler ought to be placed further forward to create a turbulent flow over a larger surface. But when I think of it, the sailplanes that I sometime fly have their spoilers around the first third of the wing and this works well. Why would I want a spoiler on the aft part? I can't really find a reason for it now, except if I was to design the wing using flightspoilers for lateral controll. Am I getting the picture now?
keep your thoughts coming!
cheers/lns
[ 28 November 2001: Message edited by: low n' slow ]
[ 28 November 2001: Message edited by: low n' slow ]
Depends on where you are... Stockholm is really nice during the summer months but it gets really grey and horrible during winter. The Great North is quite nice during both seasons but everything is alot slower up there. Dunno why really but it's like the Twighlight zone all the time...
My conclusion for the time being is that a spoiler intended to depleat speed only should be at the rear. This should have the effect of not destroying so much lift, simply creating huge amounts of formdrag.
A liftdumper or ground spoiler ought to be placed further forward to create a turbulent flow over a larger surface. But when I think of it, the sailplanes that I sometime fly have their spoilers around the first third of the wing and this works well. Why would I want a spoiler on the aft part? I can't really find a reason for it now, except if I was to design the wing using flightspoilers for lateral controll. Am I getting the picture now?
keep your thoughts coming!
cheers/lns
[ 28 November 2001: Message edited by: low n' slow ]
[ 28 November 2001: Message edited by: low n' slow ]
