Leading Edge Slat Forces
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Leading Edge Slat Forces
Hi
Regarding the title, I wanted to be explicit about what I was talking about and I am using the American nomenclature. Coz, slats are unpowered devices in my world, but America does not think so, (long live Frederick Handley Page).
Anyway, what sort of forces would be required to extended a 'slat' prior to landing on something like a 767?
Mark
Regarding the title, I wanted to be explicit about what I was talking about and I am using the American nomenclature. Coz, slats are unpowered devices in my world, but America does not think so, (long live Frederick Handley Page).
Anyway, what sort of forces would be required to extended a 'slat' prior to landing on something like a 767?
Mark
In our world, slats are not unpowered. Mine are hydraulicly operated. As to the forces required to extend them, I'll leave that to the experts!
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Where is your "world"? Can I have one of my own?
I'm not sure what America does or doesn't think about "slats" (or did you mean "slots"). I'm pretty sure that a typical American (of the USA variety) doesn't think much about "slats" (or "slots"). If and when he does, he would probably allow for "slats" to be powered or unpowered.
You might want to sit down for the next part. Despite your fervent prayer, Frederick Handley Page has passed on.
I'm not sure what America does or doesn't think about "slats" (or did you mean "slots"). I'm pretty sure that a typical American (of the USA variety) doesn't think much about "slats" (or "slots"). If and when he does, he would probably allow for "slats" to be powered or unpowered.
You might want to sit down for the next part. Despite your fervent prayer, Frederick Handley Page has passed on.
Last edited by Crabman; 23rd Nov 2012 at 11:20. Reason: Adeed some sad news.
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I'm not sure what America does or doesn't think about "slats" (or did you mean "slots
ts?
Last edited by de facto; 23rd Nov 2012 at 12:26.
As I understand it a slot is a fixed device and a slat is retractable. Therefore you get the advantage of a slot at low speed, without the drag penalty at higher speeds.
A "fixed" slat is in fact a slot.
A "fixed" slat is in fact a slot.
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Automatic - the slat lies flush with the wing leading edge until reduced aerodynamic forces allow it to extend by way of aerodynamics when needed. Sometimes referred to as Handley-Page slats.
Had them on the Tiger Moth and the North American Sabreliner, Which had NA Sabre wing.
Two types I have flown
Had them on the Tiger Moth and the North American Sabreliner, Which had NA Sabre wing.
Two types I have flown
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Ref: AA flt191 and un controlled deployment of slats as a result of broken hyd lines when #1 engine departed the aircraft. So I would say yes slats are hydraulically controlled and deployed under most normal circumstances.
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Re slats and slots - my understanding from many years ago is that a slot is a channel cut in the wing section near the leading edge whereas a fixed slat is an aerofoil section fixed and extended forward from the leading edge. Therefore they are NOT the same. However, "that is not important right now".
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DLE - emptied Google looking for that. A new one for me. Any link? What about the slatless slot?
Time, perhaps, to ask if a deployed slat creates a slot - no, I thought not.
Time, perhaps, to ask if a deployed slat creates a slot - no, I thought not.
Last edited by BOAC; 23rd Nov 2012 at 16:03.
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Wow, where to start.
I'd chosen the technical forum for a technical discussion. Instead every participant bar one has commented on terminology. Thank you OK465, you are correct. I should have referred to them as leading edge devices.
MarkerInbound, thank you for your contribution. 3000 psi is a measure of pressure not force. Additionally, the leading edge devices are generally powered by a torque tube running behind the fixed leading edge. This can be powered by a hydraulic motor, usually in the left wing root, which will have 3000 psi powering it. But how much power does the hydraulic motor put out?
There are publications out there that refer to Handley Page Slats as being unpowered leading edge devices. This is what I have learnt. I am confronted with Boeing SRM's that refer to beams as chords, straps as chords, stringers as chords. Yet I learnt a chord is a measurement of distance between the leading and trailing edges of a wing. I suppose this is another example of the golden rule, he that hath the gold maketh the rules.
I think that Lachmann also referred to his leading edge devices as slats, (quick Jeeves look up Lachmann).
My comment "long live Fredrick Handley Page" should have read "long live the memory of Frederick Handley Page". An independant thinker ostracised from British aerospace.
After all that, does anyone know the sort of forces invovled in extending the leading edge devices at say 160 knots?
I'd chosen the technical forum for a technical discussion. Instead every participant bar one has commented on terminology. Thank you OK465, you are correct. I should have referred to them as leading edge devices.
MarkerInbound, thank you for your contribution. 3000 psi is a measure of pressure not force. Additionally, the leading edge devices are generally powered by a torque tube running behind the fixed leading edge. This can be powered by a hydraulic motor, usually in the left wing root, which will have 3000 psi powering it. But how much power does the hydraulic motor put out?
There are publications out there that refer to Handley Page Slats as being unpowered leading edge devices. This is what I have learnt. I am confronted with Boeing SRM's that refer to beams as chords, straps as chords, stringers as chords. Yet I learnt a chord is a measurement of distance between the leading and trailing edges of a wing. I suppose this is another example of the golden rule, he that hath the gold maketh the rules.
I think that Lachmann also referred to his leading edge devices as slats, (quick Jeeves look up Lachmann).
My comment "long live Fredrick Handley Page" should have read "long live the memory of Frederick Handley Page". An independant thinker ostracised from British aerospace.
After all that, does anyone know the sort of forces invovled in extending the leading edge devices at say 160 knots?
nz,
You're still not being clear- do you mean LEDs as found on modern Jets, in which case the answer is "3000psi of hydraulic power", or unpwered slats, as in a Tiger Moth, in which case the answer is "Spring Pressure".
If it's the latter, the slats are spring-loaded open. When there is sufficient airflow, the pressure forces them them shut. They can also be locked shut mechanically
Not going to happen a 160kts as the Tiger would have shed it's wings by then!
Someone mentioned the Sabre liner, and by inference the F-86 having unpowered slats? I wasn't aware of that, but would be interested to know if that is the case.
You're still not being clear- do you mean LEDs as found on modern Jets, in which case the answer is "3000psi of hydraulic power", or unpwered slats, as in a Tiger Moth, in which case the answer is "Spring Pressure".
If it's the latter, the slats are spring-loaded open. When there is sufficient airflow, the pressure forces them them shut. They can also be locked shut mechanically
Not going to happen a 160kts as the Tiger would have shed it's wings by then!
Someone mentioned the Sabre liner, and by inference the F-86 having unpowered slats? I wasn't aware of that, but would be interested to know if that is the case.
Last edited by Wizofoz; 24th Nov 2012 at 08:21.
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Thanks, mike- yes, although I did not work for either BEA or BOAC I am familiar with a Drooped Leading Edge (but, like Google, not with 'DLE'.which is, I think, either a skin condition or a French airport
) It was DR's "the slotless slat" that threw me.
NZ - if this really bothers you, why not try the '1/2 rho Vsquared S' using a flat plate coefficient? Or you could just use <3000psi? Since basic sprung automatic slats 'pop out' due to low pressure at the l edge, I suspect the forces are not great.
I believe the slatted F-86 (before they adopted the 'f c e l e a ' for DR) had automatic slats, but whether sprung or hydraulic I know not
) It was DR's "the slotless slat" that threw me.NZ - if this really bothers you, why not try the '1/2 rho Vsquared S' using a flat plate coefficient? Or you could just use <3000psi? Since basic sprung automatic slats 'pop out' due to low pressure at the l edge, I suspect the forces are not great.
I believe the slatted F-86 (before they adopted the 'f c e l e a ' for DR
) had automatic slats, but whether sprung or hydraulic I know not