Evolution of Design

We've all done. Taken pencil to paper and started to draw something we saw in our minds. Maybe it was a simple scetch of something you needed to modify around the house, or a simplistic car you drew as a child. Even stick figures of family and friends. What about aircraft? If you are a member of this site and others like it, there is a good chance you have done just that. But how do you go from a simple drawing to a working model? How do you refine that design to make it truely good and somthing you want to share with others? This is a story about one of my designs, and how I am continually working to make it beter and evolve it into other models.

For me it starts with a simple drawing. I actually keep a small notepad with me at all times. I've actually filled up several of these notepads over the years. Everything from notes for my work to my own designs for planes and other projects. In this case, the design that would become my F/A-241 Shrike. I drew this back in July of 2012 and have since been continually updating the design to make it beter, stronger, more controlable and fun to fly.

After I drew this I was so unsure of if it would even fly that I decided to make a small chuck glider. This tiny chuck glider is only about 9" wide. This is the very first F/A-241 Shrike ever made, and it was powered by a tiny ruberband slingshot.

Once I had determinde that it would fly I began full sized plans on some posterboard. I had to decide on what size the final airframe would be and also the style of construction. I decided on a style of wing I had only done with the build of my Funabts, a KF-2 wing with a box fuslage. I knew I had to keep it light to make sure it would fly. I had made a Mini-Funbat with a 19" wingspan and had recived some tiny 460mah 3s packs for that project and decided I would use those along with some AX 1806N 2900kv motors that I had turning a 6"x4 prop.

I decided to go with a 20" wingspan, useing the full width of a sheet of Readi-Board from Dollar Tree. Once I had stripped it of its paper I began hotwireing out the parts for my new design. The paper adds some strength to the foam, but easily peels away with any moisture. The area where I live has enough moisture in the air that the paper peels away very easily. I did not want to have my plane come apart midair, so the paper had to go.

The finished airframe came out light, very light. 160grams total flying weight. The nose was left open as a vent to keep the battery and ESC cool with an opening at the rear for the motor wires and air to exit.

Time came for the first flight of the aircraft. The aircraft tracked well and went with little difficulty. The tiny motor and battery where perfict for the light airframe. The only draw back was me. It was clear that this was beyond my skill range in terms of controlling a small, fast and highly manuverable aircraft. The crash was soon to follow.

I soon after started building the second prototype, the YF-241B.

This had a number of advancments over the first. I changed the canard to a thinner, longer design to get it into more air. The wing also now had a slight step where the tail attached, giving the wing about 2" larger wing area. I also switched to a KF-4 wing to help deal with the gusty winds in my area. I also added a rounded corner where the wing met the root. This was as much an areodynamic chioce as much as keeping the foam strong. I had learned long ago that sharp inside corners on foam tend to be a starting point for cracks on foam. Since this area is right where the planes center of gravity is located it also was a stress point. Any extra strength would be a plus.

I also started to use small cardboard tabs to help lineup and lock the removable hatches in place. The new airframe had grown to 184 grams with the KF-4 wing. I also was able to place the sevos inboard, underneath the fuselage.

The addition of winglets helped with the wingloading of the aircaft and added some stability in level flight. Now at 190grams the airframe was begining to become somthing truely controlable. I began exploring its range of manuverability and altering it looks. So began the YF-X-241 project.

I wanted to move away from the canards being mounted on the same line as the main wing, and give them thier own path of clean air that would not disrupt the air of the main wing. I also tried moving the servos out, midway on the wing mounted in their own pods. This gave the YF-X-241 a distinctive look. It greatly reminded me of one of my favorite designs, the VF-4 Lighning III from Macross. I also gave the canopy cleaner lines, doing away with the step it had.

While building the first YF-X-241 some issues began to show with the YF-241B. The open nose vent became a major weakpoint. The tiny peice of foam that slightly closed the nose and allowed the canopy to clip shut would break off easily, sometimes from simply trying to fit the canopy inplace after plugging in the battery. The nose had to be closed off the make it stronger. Other vents would be added to keep things cool.

A crash of the YF-241B also resulted in exposing another flaw, the canards would take the brunt of impact in a bad landing. Removing the canards all together was the next step, though there was now not enough lift on the front to keep it in the air.

Test flight of the first YF-X-241 also showed that the canards having been moved back would result in the same effect. Low speed flight was nearly unresponcsive. I could only control the airframe at high speeds, speeds beyond my skill level at the time. The crash snapped the plane in half. So began the search to make the canards movable.

I had to move the servos back in close to the fuselage. The wings would flex in flight, reducing the range that the control surfaces would move. Also keeping the weight as close to center would improve manuverability. I also now was useing large peices of cardboard to stiffen the fuselage around the "cockpit" area. This also made it simple to line up the canopy and keep it locked in place.

I managed to place a servo just behind the battery linked to the canards with a bit of silicon tubing to make the angled bend to link them together. A simple set up that worked very well. Again the result was the same. Too little control at low speed. I was unable to pull out of a dive due to the limited elevator control of the canards so close to the center of gravity. The next version would have a longer fuselage and larger wing.

This would also be the first version where the tails would have a notch cut into the wing to make the tails stronger. It would also be powered by a larger, C20 2050kv motor and a 7"x3 prop.

A new canopy brace would also be used to help keep the forward fuslage together. Again, control was still an issue. The canards still had little control. It made for a good cruiser, but lacked the manuverability I was aiming for. The YF-X-241 project was heading twords failure.

All the advancements made to this point and my increase in controling skill had begun to show that the standard (now renamed) F/A-241A and F/A-241B models had an extreem amount of manuverability. The aircraft would pull loops inside of 10' at half throttle. Its low speed, low altitude manuverability made for an almost 3D pusher level of performance. I began making alternate parts. Different canard and tail designs would offer for a wide range of customization of the airframe for who ever would build one.

The F/A-241C. Instead of a canard, I was able to give it a wide wingroot to support to front end in flight, and not have to worry about a canard breaking in a bad landing. Vents on either side of the nose would alow for airflow into the fuselage to keep everything cool, while vents on the rear cover would help pull air out.

I was still not able to let go of the failed YF-X-241 project. The look of the canards up high on the fuslage, the pods on the tails that look like it had outboard engines. I had to keep that alive somehow.

Enter the F-242 Spiker. While the F/A-241 Shrike possesed the agility at low speeds and be the equivilent of a ground attack aircraft, I wanted to F-242 to be more of a pure Fighter/Intercepter. The larger wing, similar to my old YF-239 Sparrow, with a steeper sweep, the YF-X-241s stretched fuslage and high mounted canards gave it the look I was after. While the F/A-241 was a bit twitchy at high speeds due to its massive control surfaces, the F-242 was smooth and easy to control, even being powered by a KEDA 2730/3000kv motor slinging a 7x3 prop. Though loops would be larger, its ability to punch through wind and fly at high speeds would make for an eaiser to control aircraft. I was also now running the F/A-241 on a 610mah pack and the new F-242 on a 750mah pack. Both designs where now pushing 220-230 grams. This was partly due to switching from spray glues to rubber cement. I was tired of the overspray mess of spray glues, plus their lack of holding ability over time. A new design for the nose would also give both an increased stregth for bad landings.

I was also able to acheave a goal I had been trying to reach, to create a "Standard Fuselage" to base my models around. Even I continue to evolve the design. Creating new models. Some good, some not. Only time will tell where I am able to push my skills of design, for good or bad. But as a gift for reading this, here is a taste of what is to come. The F-243 Hunter.

Thank you for taking the time to read my story. I only hope it serves to give some of you the confidance to draw and build your own creations, and the curage to keep at it even when fialure comes.