JerryFlyGuy
Well-Known Member
I've been working on various designs for a while now. One issue I come up w/ regularly is to get a feel for what coef. of lift a person should use while assuming flaps. I've got Fowlers book and depending on various variables [ % or Mac's for flap chord, Re#'s etc] it list a CsubL increase of up to 2.6 [non-flaped CsubL of 1.45] this is taken at 1.4 x10^6 Re with a 30% mac flap [mean] I'm wondering if this is something that a guy can use w/ some confidence. I know these numbers aren't 'take it to the bank' kinda numbers but.. can we expect accuracy to w/in 0.3 CsubL? [Thats 12% @ max. if you want to look at it another way]
Also you designers out there. What's you feel on a light twin's stall speed? I'm planning on a Vmca below my stall speed by several knots. I have looked at FAR part 23 but can't remember their numbers. [And can't find where I put it now] I'm thinking somewhere in the range of 75 mph @ GTOW. This wouldn't come down a whole lot at zero fuel [ 6-8 mph] but As a corporate pilot [C-414A] when I get the plane slowed down much below 110 I've got a pretty good hold on the seat anyway, if you know what I mean. Its not that I'm scared to go that slow I do pretty much each trip I fly as we are based out of 2500' but at 7000# that bus isn't ment to be toodling around at that speed.. a good wind gust/shear and you got problems. I dunno, I'm not scared of a 80mph stall speed but then if I was to ever put the a/c into kit production then some customers might be concerned.. Input welcome on this one.
I guess another way of looking at that one is.. what do you feel is a max wing loading number to be comfortable w/? Some Lancair Iv's are well up over 35!
Another factor is wing efficency.. I'm working w/ 85% as a ruff number based on a tapered wing w/ a straight leading edge[toying w/ the idea of up to 5deg forward sweep for c/g reasons]. A/r of 9. Is this even in the ball park for ruff numbers. [ this is more a 'whats been your experiance' kinda question]
I've got many more questions but for now.. I'll sit back and see what ppl think..
JerryFlyGuy
Also you designers out there. What's you feel on a light twin's stall speed? I'm planning on a Vmca below my stall speed by several knots. I have looked at FAR part 23 but can't remember their numbers. [And can't find where I put it now] I'm thinking somewhere in the range of 75 mph @ GTOW. This wouldn't come down a whole lot at zero fuel [ 6-8 mph] but As a corporate pilot [C-414A] when I get the plane slowed down much below 110 I've got a pretty good hold on the seat anyway, if you know what I mean. Its not that I'm scared to go that slow I do pretty much each trip I fly as we are based out of 2500' but at 7000# that bus isn't ment to be toodling around at that speed.. a good wind gust/shear and you got problems. I dunno, I'm not scared of a 80mph stall speed but then if I was to ever put the a/c into kit production then some customers might be concerned.. Input welcome on this one.
I guess another way of looking at that one is.. what do you feel is a max wing loading number to be comfortable w/? Some Lancair Iv's are well up over 35!
Another factor is wing efficency.. I'm working w/ 85% as a ruff number based on a tapered wing w/ a straight leading edge[toying w/ the idea of up to 5deg forward sweep for c/g reasons]. A/r of 9. Is this even in the ball park for ruff numbers. [ this is more a 'whats been your experiance' kinda question]
I've got many more questions but for now.. I'll sit back and see what ppl think..
JerryFlyGuy
