A few months back i purchased a Hobbyking Bonsai flying wing and set it up as a gift for my friend. Of course i had to "test fly" it. Which i ended up doing almost every lunch for a couple weeks until i was able to give it to my friend.
Realizing that i really missed having a small flying wing i decided to try my hand at one of the OSW's. I loaded up a couple delta wing CG calculators and started playing around with numbers. I already knew that i wanted it to be exactly the same width as the foamboard, so the wing span was 20". I also really like how Alex Grieves planes usually have the wing spar right around the cg so i wanted the kfm step to "step down" right around cg to make this easy to find in the field. Also, as everyone knows that flys wings, CG is a real pain so i wanted the cg to not be forward at all if i could help it. Partly this was solved by the design of the wing and partly by cutting the motor forward into the wing.
Here are the numbers that i came up with in the calculator. I didn't have to adjust any of this to make it fly.
I found an online graph paper program to map out how much of the sheet it would take:
Flying weight: 162
Cubic Wing loading: 7.5
Construction was to hot glue all 3 sheets together and cut a bevel on leading edge. Than i smeared hot glue to the leading edge add some strength, much like flitetest does for the hot glue hinges.
Maiden went well. Knowing that little planes are twitchy as all heck i had already dialed the throws way down. The maiden flight is very short mainly because it is getting dark and both sides of the plane are white. I was losing orientation quick. Assuming i get the same flight times as i was on the bonsai (same parts) i expect 5 minutes or so. Cg was right where the half step meets the full wing.
Maiden flight and Pics:
Realizing that i really missed having a small flying wing i decided to try my hand at one of the OSW's. I loaded up a couple delta wing CG calculators and started playing around with numbers. I already knew that i wanted it to be exactly the same width as the foamboard, so the wing span was 20". I also really like how Alex Grieves planes usually have the wing spar right around the cg so i wanted the kfm step to "step down" right around cg to make this easy to find in the field. Also, as everyone knows that flys wings, CG is a real pain so i wanted the cg to not be forward at all if i could help it. Partly this was solved by the design of the wing and partly by cutting the motor forward into the wing.
Here are the numbers that i came up with in the calculator. I didn't have to adjust any of this to make it fly.
Main Wing:
Kfm4 Steps (one on top and bottom)
- Wingspan: 20"
- Root Chord: 8"
- Tip Chord: 4"
- Sweep distance: 6"
- CG: 3.91"
- Sweep distance from trailing edge of wing tips to trailing edge of body: 2"
Kfm4 Steps (one on top and bottom)
- Root chord: 4"
- Tip Chord: 2"
- sweep dist: 6"
I found an online graph paper program to map out how much of the sheet it would take:
Flying weight: 162
Cubic Wing loading: 7.5
Electronics:
- 9g servos
- frsky 6channel rx
- DYS BX1306 3100kv motor
- 5x5 apc prop
- 12a esc
- 450mah 2s battery
Construction was to hot glue all 3 sheets together and cut a bevel on leading edge. Than i smeared hot glue to the leading edge add some strength, much like flitetest does for the hot glue hinges.
Maiden went well. Knowing that little planes are twitchy as all heck i had already dialed the throws way down. The maiden flight is very short mainly because it is getting dark and both sides of the plane are white. I was losing orientation quick. Assuming i get the same flight times as i was on the bonsai (same parts) i expect 5 minutes or so. Cg was right where the half step meets the full wing.
Maiden flight and Pics:
