spaatz1084
Member
- Joined
- Nov 22, 2007
- Messages
- 8
I noticed that the VNE for the Corben Junior Ace has been quoted between 100 and 135 mph, but I have never been able to find any definitive or authoritative source for VNE. To that end, I wanted to create a Vg/Vn diagram for the aircraft and establish all the necessary V speeds, and I am using both the ASTM and FARs as my guides. While this has been very informative so far, I am still having trouble getting the exact data I need and making sense out of some of the numbers. I was hoping someone out there could provide me with some answers, resources, or clarity.
First, the aircraft has a “modified” Clary Y airfoil (which seems to be just a regular Clark Y with a 54 in instead of a 60 in chord). I have been trying to find some authoritative resource for data on this airfoil for my calculations such as the zero lift angle of attack, CL max, angle of attack for CL max, etc. The best I can find is some old NACA data with Reynolds numbers that only equate to about 65 miles per hour. The cruise of the aircraft will be much higher than this. Where can I find the airfoil data I need to calculate the +CNA and –CNA curves?
Second, can someone explain some of the V speeds to me? The ASTM and FARs give formulas for calculating some speeds or providing minimum or maximum values for some airspeeds, but my results seem to me all over the place. Can someone explain VC and VC min to me and how these numbers are derived? In some cases, these speeds seem to be almost arbitrarily chosen by the designer. What is the purpose behind VC? Why do most Vg/Vn graphs show this speed intersecting the +50 fpm gust load line?
I am also confused about VH and VD which also seem to be almost arbitrarily chosen. What is the purpose behind these numbers and how do you determine them (other than actual flight testing)?
Thanks,
Jon
First, the aircraft has a “modified” Clary Y airfoil (which seems to be just a regular Clark Y with a 54 in instead of a 60 in chord). I have been trying to find some authoritative resource for data on this airfoil for my calculations such as the zero lift angle of attack, CL max, angle of attack for CL max, etc. The best I can find is some old NACA data with Reynolds numbers that only equate to about 65 miles per hour. The cruise of the aircraft will be much higher than this. Where can I find the airfoil data I need to calculate the +CNA and –CNA curves?
Second, can someone explain some of the V speeds to me? The ASTM and FARs give formulas for calculating some speeds or providing minimum or maximum values for some airspeeds, but my results seem to me all over the place. Can someone explain VC and VC min to me and how these numbers are derived? In some cases, these speeds seem to be almost arbitrarily chosen by the designer. What is the purpose behind VC? Why do most Vg/Vn graphs show this speed intersecting the +50 fpm gust load line?
I am also confused about VH and VD which also seem to be almost arbitrarily chosen. What is the purpose behind these numbers and how do you determine them (other than actual flight testing)?
Thanks,
Jon
