Tuesday, October 06, 2015
Kfm3 Flying Wing Build Log 01
After some thought, I've decided to build the following
- Kfm3 airfoil with 4:1 aspect ratio.
- A pod or fuselage of sorts below that will hold most of the electronics.
I quickly did some calculations on the flying wing calculator, and the CG is about... 4cm from the leading edge. I'm not sure what this plane is going to look like... but man, I gotta have some weight up front!
The Kfm3 airfoil is selected based on its heavy lift capabilities, as well as for ease of build. As the wing design I'm going with is totally rectangular, it is extremely easy to measure and cut out. Also, the ability to put in several spars (thinking of just 2 spars, really) to stiffen things up is really enticing.
Right now, I have a 9.5mmx9.5mm basswood stick, which I think may be too thick. So, I'm going to Michaels tomorrow to see if they have a 5mm square basswood stick, if not I'll just wing it and use the 9.5mm. It should prove superbly strong. I'll also have to be careful how to mount the servos, as I want them near the spar to properly support the wing and not allow the wing to lose its stiffness.
The pod below is not properly thought out yet, but it's going to be based on the pods seen on Experimental Airlines. Mine though, will be much smaller with a 4cm inner diameter - the widest thing I'm fitting into the wing is the battery, which is about 37mm wide. I was considering designing it to fit a gopro, but I'm not ready to send up a few hundred bucks into the air, experimental design or not!
Now in a previous post, I mentioned I wanted to have the motor up high, so as not to strike the ground. This may not be the best of ideas as the motor needs to go rather high, or, I need some long landing gear.
Given I'm not in the landing gear fan club thanks to the weight, and that I do not have a proper "runway" to take off from, I think I'm scraping that idea, but am very interested to try out how folding props work, so I'll go with that instead. Perhaps I'll have skids of sorts under the wing? No idea yet. Or, I could just have extra tall winglets that extend below the wing. I need to remind myself that the winglets need to be behind the CG for them to work properly.