Hello everbody, I'd like you to meet Toothless!
Toothless is the first scratchbuild aircraft that I have personally designed. He has a wingspan of 60 inches, is 45 inches long, and is powered by Power Pack C. He has no ailerons (although they wouldn't be very hard to add) and relies solely on a V-tail for flight control. Best of all, he actually flies!
(Video of the maiden flight is at the bottom of the article)
I first started thinking about Toothless after I saw a posting on facebook for Flite Test's STEM program. They had a picture of the MF Toothless built by Mesa RC (http://flitetest.com/articles/mf-toothless) and it immediately captured my imagination. Up until this point I had only built and flown several of the basic Swappable Scratch-Builds (FT Flyer, Nutball, Versa Wing, etc.) and I had never tried making a plane of my own. But when I saw the MF Toothless, I was inspired and immediately started planning how to build my own.
Two days after I saw that facebook post, I started building. I didn't really take the time design or plan at all. I had a pretty good idea in my head of what I wanted it to look like and how it would function, but I didn't have plans or even solid dimensions. I kinda just made it up as I went along.
The first step was to create the wings. I figured I would make the wings as big as they could be and then base the dimensions of the rest of the aircraft on that. The dimensions for the wing were based on the Simple Soarer wing. I used those dimensions (6 inches on bottom surface, 7 inches on top surface) to make the basic airfoil. Then, I added the dragon wing embellishments to the trailing edge and wingtip.
Folding the airfoil was a bit different from the simple soarer because I had so much protruding off of the trailing edge. If I had just glued the two pieces together the back of the wing would have extended below the bottom surface of the airfoil. So I added a spacer (similar to the Spitfire Swappable) to keep the trailing edge of the wing in line with the bottom surface.
The next step was to make the fuselage. I made the tail spar first because it was simple, just a triangular spar with 2 inch sides. The main body of the fuselage was a bit trickier. I originally planned to make it triangular as well, with a tapered nose and tail, but as I built it I decided that I didn't like the look of it or the wasted space. So I modified the design as I went along and ended up with a sort of trapezoid... thing... I then put the holes and bbq skewers for holding in the power pod. Finally, I inserted and glued the tail spar into the back of the fuselage.
Attaching the wings was kinda tricky. I originally thought to make a spar which would hold the wings out to the sides of the fuselage, but that ended up being way to weak. So I ended up gluing the wing roots together, with a slight dihedral, and then gluing them to the top of the fuselage with insane amounts of hot glue. I'm not terribly proud of this wing mount, but it works, so I can't really complain.
Making the tail was really just a shot in the dark. Like I said before, this is the first plane that I had ever designed and I didn't really have any solid knowledge about sizing or placement of the tail. So I kinda just went with what looked right and hoped for the best.
I decided to do a v-tail for several reasons. First, it would look the most like the actual Toothless. Second, it only required two servos (I am very thrifty with my use of servos). Finally, I was just curious. I've never flown a v-tail before and I wanted to see how it handled.
So like I said, I kinda guesstimated on the sizing of the stabilizer and ruddivators (elidders?) and attached them to the surface of the tail spar. However, this put the angle between the tail surfaces at about 60 degrees. After doing some internet research, I discovered that a more ideal angle would be 120 degrees. So i had to split the tail spar along the bottom and sides near the tail, cut some foam out, and re-glue it. I then added a couple of bbq skewers to replace the strength I compromised.
The servos for the control surfaces were placed at the rear of the fuselage body. This wasn't ideal because the pushrods have a lot of space to buckle, but it was the most feasible based on the materials I had (I had really long push rods and no servo wire extensions). I then ran a really long pushrod back along the tail and through a couple of coffee stirrer straws to the control surfaces.
And, just for fun, I added eyes and painted one of the tail fins =)
I went out to fly this for the first time with about a 75% certainty that he would fly for about 10 ft, go belly up, and die. So I was incredibly surprised when he took off and flew! And flew incredibly well! Like, really well!! I honestly cannot get over how well he flew. I have flown several planes with varying controls surfaces (rudder-elevator, aileron-elevator, elevons, etc.) and Toothless honestly was one of the easiest and most stable planes that I have flown. The v-tail allowed for perfect control for easy soaring. I was even able to do a couple of loops! The turning was pretty passive and he was extremely stable, so I didn't try any barrel rolls, but I am ok with that. He was just a pleasure to fly. Very stable and very easy to control!
Also, I know how rare it is to have such a successful maiden flight. I got very lucky. Very, very lucky. And after having flown him around, I am perfectly happy with the design and I don't plan to make any changes. You could add ailerons, it would be pretty simple. But like I said, I'm stingy with servos and I'm currently very happy with how he flies.
So there you have it. My first scratchbuild! I hoped you enjoyed reading about it. I don't currently have any plans drawn up for him, but I have decided that if enough people express interest and request plans, I will take the time to draw some up.
Thanks for your time and good flying!!