Been mulling this one over for a while and tinkering with the model in Sketchup. Time to pull the trigger on building this.
The model in Sketchup is pretty much done. The wings are just placeholders and need more work. The curved spine of the original is pretty hard to match but I think it will look okay.
Rough specs:
Wingspan: 46 inches
Length: 40 inches
Power: 2 x E-flite Motor 10 (1300kV) wearing 9 x 6.5 three bladed props. Will Probably use 2 x 2200mAh 3S in parallel
Target AUW: Think I can keep it to 4lbs or less
Plans - I will post plans here once the build is finalized.
Build - I will post links to the posts where I describe the build steps here.
This is the final product....
Wing Build
The scale was driven by the available motors and subsequent estimates of what diameter 3-bladed prop I could use and buy. I happen to have two E-flite Motor 10 units which I got from some guys at the field (one was surrounded by a beat up Timber). On the Timber, whose AUW is just over 3 pounds, this motor spins a 12 x 4 prop. One approach for dealing with blade number conversions was described as calculating the prop load as D^3 x P x Sqrt (N-1) where D is the diameter, P is the pitch, and N is the number of blades (apologies for the math). So for the 12 x 4 2-bladed prop this works out as approx. 6900 (not sure what the units are supposed to be). I had a rough idea that a 9 inch 3-bladed prop would produce much the same load. Then I found 9 x 6.5 B-25 3-bladed replacement props at Motion RC. If you run the numbers on this prop, the load is 6700. Pretty close. To check the numbers I measured the static thrust, Amps, and RPM for the two props at full throttle.
12 x 4, 2-blade prop generated 4.4 lbs of thrust at 10400 RPM pulling 31 amps
9 x 6.5, 3-blade prop generated 3.4 lbs of thrust at 9700 RPM pulling 38 amps
So the three blade props are pushing the motor a little on the hard side, but it should be fine. Also should have no issues with power if I can hit the target weight of 4 lbs.
DamoRC
The model in Sketchup is pretty much done. The wings are just placeholders and need more work. The curved spine of the original is pretty hard to match but I think it will look okay.
Rough specs:
Wingspan: 46 inches
Length: 40 inches
Power: 2 x E-flite Motor 10 (1300kV) wearing 9 x 6.5 three bladed props. Will Probably use 2 x 2200mAh 3S in parallel
Target AUW: Think I can keep it to 4lbs or less
Plans - I will post plans here once the build is finalized.
Build - I will post links to the posts where I describe the build steps here.
This is the final product....
Wing Build
The scale was driven by the available motors and subsequent estimates of what diameter 3-bladed prop I could use and buy. I happen to have two E-flite Motor 10 units which I got from some guys at the field (one was surrounded by a beat up Timber). On the Timber, whose AUW is just over 3 pounds, this motor spins a 12 x 4 prop. One approach for dealing with blade number conversions was described as calculating the prop load as D^3 x P x Sqrt (N-1) where D is the diameter, P is the pitch, and N is the number of blades (apologies for the math). So for the 12 x 4 2-bladed prop this works out as approx. 6900 (not sure what the units are supposed to be). I had a rough idea that a 9 inch 3-bladed prop would produce much the same load. Then I found 9 x 6.5 B-25 3-bladed replacement props at Motion RC. If you run the numbers on this prop, the load is 6700. Pretty close. To check the numbers I measured the static thrust, Amps, and RPM for the two props at full throttle.
12 x 4, 2-blade prop generated 4.4 lbs of thrust at 10400 RPM pulling 31 amps
9 x 6.5, 3-blade prop generated 3.4 lbs of thrust at 9700 RPM pulling 38 amps
So the three blade props are pushing the motor a little on the hard side, but it should be fine. Also should have no issues with power if I can hit the target weight of 4 lbs.
DamoRC
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