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#1
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Flap angles
I was leafing through the C172N POH for some flap settings yesterday and a
thought occured to me: there was a post here about some verions of the 172 having different full flap angles - some have 40 and 38 degrees. So i wonder, how do they determine these angles for all flap settings when the plane's still on the drawing board? Or is it an airfoil design thing? I've noted that for example the Learjet 45 has first setting at 8 degrees. How do they determine what is the right angle for each setting? Triple Delta |
#2
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"DeltaDeltaDelta" wrote in message
... I was leafing through the C172N POH for some flap settings yesterday and a If you read Russian (who knows, you might , check out this paper: http://www.sla.ru/aviamaster/zipfiles/mexan_wing.pdf it pretty much answers all your questions and more. HECTOP PP-ASEL-IA http://www.maxho.com maxho_at_maxho.com |
#3
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They don't write the POH (AFM) until they've performance tested the
prototypes. -- John T Lowry, PhD Flight Physics 5217 Old Spicewood Springs Rd, #312 Austin, Texas 78731 (512) 231-9391 "DeltaDeltaDelta" wrote in message ... I was leafing through the C172N POH for some flap settings yesterday and a thought occured to me: there was a post here about some verions of the 172 having different full flap angles - some have 40 and 38 degrees. So i wonder, how do they determine these angles for all flap settings when the plane's still on the drawing board? Or is it an airfoil design thing? I've noted that for example the Learjet 45 has first setting at 8 degrees. How do they determine what is the right angle for each setting? Triple Delta |
#4
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Another option is to look for an aerodynamics course at a college
near you. |
#5
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"John T Lowry" wrote in message link.net...
They don't write the POH (AFM) until they've performance tested the prototypes. I think he's asking why manufacturers designate the flap settings as they do (not which setting should be used when). For example, the G550 has flap settings of 0, 10, 20, and 39; his question is something like "why 39 and not 40?" or "why do some 172's have 40 degrees of flap avalible and others only have 38?" Or "why are flap settings not evenly spaced?" Basically, how do they determine what flap intervals should be available? |
#6
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"why do some 172's have 40 degrees of flap avalible and others only have 38?" Dunno about 38, but the newer ones have 30, because full 40 degree flaps were causing problems (which I can't recall) due to poor technique of some sort. Might have something to do with slips with flaps, IIRC. Jose -- (for Email, make the obvious changes in my address) |
#7
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"Teacherjh" wrote in message
... Dunno about 38, but the newer ones have 30, because full 40 degree flaps were causing problems (which I can't recall) due to poor technique of some sort. at 40 deg they sucked for crosswinds and that probably ruined a student or two complete with cross-control flutter, but were great for "carrier-deck" landings HECTOP PP-ASEL-IA http://www.maxho.com maxho_at_maxho.com |
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#9
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Jose,
"why do some 172's have 40 degrees of flap avalible and others only have 38?" Dunno about 38, but the newer ones have 30, because full 40 degree flaps were causing problems (which I can't recall) due to poor technique of some sort. Might have something to do with slips with flaps, IIRC. I'm always amazed at the amount of misinformation running around here. Cessna switched to 30 degrees of flap deflection maximum on a heavier model of the 172 because of rate of climb requirements during a balked landing under the FARs. The earlier airplanes could meet the rate of climb with 40 degrees, the newer ones could not, so flap travel was limited to 30 degrees. There is no problem with slips with full flaps on a 172, it's another of aviation's old wives tales. For an interesting descent rate, fly a Cessna O-1/L-19 (Model 305) Bird Dog. It had 60 degrees of flaps available. All the best, Rick |
#10
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Rick Durden wrote: Cessna switched to 30 degrees of flap deflection maximum on a heavier model of the 172 because of rate of climb requirements during a balked landing under the FARs. That's also the reason the 160hp Maule has only 40 degrees of flaps while more powerful ones have 44 degrees. Even at that, max gross is 200 pounds less than the 180hp version. George Patterson I childproofed my house, but they *still* get in. |
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