Hello,
I'm working on a college aerodynamics project on the Van's RV-7 (one of my partners is building one, so we chose it). It's nothing crazy, the class is for pilots not engineers. Anyway, for this week I need to calculate the landing roll distance for an RV-7, and part of the calculation depends on the weight distribution for the aircraft (since only the mains provide braking).
I have looked at the weight distribution from the weight and balance thread but those are taken at 0 pitch attitude (understandable to make calculating the CG easier) but in the 3 point the aircraft appears to be in about a 12 degree pitch attitude. In the absence of better data I have been estimated a 700/700/100 lb loading for a 1500 lb RV-7, which is a few % more than the numbers I saw on the W&B thread at 0 degrees pitch. I realize this will vary with CG too. For every 50 pounds more on the tailwheel, the landing roll seems to increase by about 3%. So far at 1500 lb gross weight, sea level, ISA conditions, we calculated a 341 foot ground roll with no flaps, assuming touchdown at stall speed of 48.6 KTAS (1500 lb, flaps up).
Anyway, if there is any info about this I'd appreciate it. Here is a link to the table of all the other work we've done on the RV-7 so far if anyone cares. I know it's not the most accurate since I had to make a lot of assumptions about the airfoil (extrapolated a 23013.5 from a NACA 23012 and NACA 23015 at 1,000,000 reynolds number, estimated oswald efficiency at 0.8, estimated form drag at a 0.02 additive to coefficient of parasite drag, questionable propeller efficiency model):
RV-7 Performance Spreadsheet
Developer options in excel need to be turned on for it to work right.
Thanks to anyone who responds.
I'm working on a college aerodynamics project on the Van's RV-7 (one of my partners is building one, so we chose it). It's nothing crazy, the class is for pilots not engineers. Anyway, for this week I need to calculate the landing roll distance for an RV-7, and part of the calculation depends on the weight distribution for the aircraft (since only the mains provide braking).
I have looked at the weight distribution from the weight and balance thread but those are taken at 0 pitch attitude (understandable to make calculating the CG easier) but in the 3 point the aircraft appears to be in about a 12 degree pitch attitude. In the absence of better data I have been estimated a 700/700/100 lb loading for a 1500 lb RV-7, which is a few % more than the numbers I saw on the W&B thread at 0 degrees pitch. I realize this will vary with CG too. For every 50 pounds more on the tailwheel, the landing roll seems to increase by about 3%. So far at 1500 lb gross weight, sea level, ISA conditions, we calculated a 341 foot ground roll with no flaps, assuming touchdown at stall speed of 48.6 KTAS (1500 lb, flaps up).
Anyway, if there is any info about this I'd appreciate it. Here is a link to the table of all the other work we've done on the RV-7 so far if anyone cares. I know it's not the most accurate since I had to make a lot of assumptions about the airfoil (extrapolated a 23013.5 from a NACA 23012 and NACA 23015 at 1,000,000 reynolds number, estimated oswald efficiency at 0.8, estimated form drag at a 0.02 additive to coefficient of parasite drag, questionable propeller efficiency model):
RV-7 Performance Spreadsheet
Developer options in excel need to be turned on for it to work right.
Thanks to anyone who responds.
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