Check Out my Store for more!
The Akos started out as a search for a unique frame that stood out from the common x frame. I was bored by the lack of innovation with most frames on the market, and it seemed as if most manufacturers were just making variations on each other's ideas. So, I decided I would design my own frame. By doing this, I could do everything myself, and not be subject to compromises.
I first made a list of things I wanted in my quad. I wanted it to kill the competition:
- Intuitively designed
Aerodynamics were my first major focus. The problem with current frame designs is their bulky shapes, which are not optimized for fast forward flight. The most prominent issue are the arms, which are oriented perpendicularly to the airflow of the prop, and the direction the quad is flying. According to studies done by Andy Shen, reduced airflow under the prop disk is a proven benefit for miniquads. Thus I settled on trying to make the arms parallel to the airflow by rotating them 90 degrees. This way, they would retain the structural strength of a regular arm, but would block much less air, especially from the prop. Here was my first concept drawing:
While drawing up concepts, I found the biggest issue with vertical arms was that they were simply a pain to work with. I couldn't directly mount motors to them, or much of anything to them, yet even keep them together in the shape of a quad. Oh, and I wanted it to be intuitive to put together. I eventually settled on using aluminium for the complex parts like the motor mount and the brace. Aluminium is very light, and I'm surprised it is not used on quads more. I put small notches in the arms of the frame so that they could slide into each other in the shape of an x. I then used the aluminium mounts that Nick from Cncmadness helped me create to lock the arms into place. He helped me cut a very lightweight motor mount that was shaped like a T, where the leg portion of the T shape screwed into the arm. Perfect!
The next part was the pod for all of the electronics. I despised the new and popular tower - It left everything a bit too exposed and was too tall. However, some compromises needed to be made.
The quad began to look like this:
I did indeed used the tower design, but this one was was a bit more protected, the cam was mounted in front of the guts, and it wasn't very tall. Everything was done and ready to go! Cut away!
I was so happy with it. Beautiful cut. And I immediately began with the build.. and.. that's when the issues began to arise. The arms fit perfectly together, which was great, but when I went to mount the motors, I found that the screws that mounted the motor mount onto the arms got in the way of the actual motor screws, so I could only mount two of them - not optimal. The next issue was when I tried to mount the pod: The bottom screws for the standoffs wouldn’t fit onto the arms halfway because the brace didn’t have these little cut outs:
So I had to painstakingly file them. Over Thanksgiving I was finally able to finish the quad and get the electronics working. I expected to get it flying immediately, but I noticed severe vibration on the arms when the motors spooled up. The arms would wiggle frantically and as a consequence the quad would go insane as well. What puzzled me was when I ran the motors through betaflight, the vibration didn’t happen. And the vibration only happened at certain motor speeds only when I used the transmitter. This led me to think that there was some sort of small PWM pulse deviation between the escs which would (somehow) affect the sync between the motors, creating a resonating harmony at a certain rpm level with the arms causing them to freak out.
After a lot of failure just trying to see if the culprit of the "freakout" was actually the arms, I decided that, although the arms were super sleek at 3mm, were simply too thin. Additionally, their design did not help at all either. The motor, which was mounted on top, exerts a lot of gyroscopic force on the arm, and by being on the top, it had a too much leverage over the arm and could twist it. I decided thickening the arms would help. I emailed Nick and asked him to cut 4mm and 5mm arms, just incase 4mm did not work.
After I had received the new arms, it was evident that 5mm was way overkill, and that 4mm was perfect. There was very little movement at all, which was great. After installing the new arms, the quad could finally fly! No more insane wobbles. It hovered surprisingly quietly - most likely because of the reduced profile under the prop disk.
I was so psyched after its maiden flight. I met with Andy from Shendrones and had a ton of fun really flying it for the first time. I thought all of my problems were over! Andy had some great suggestions which I wanted to implement (..eventually..). However, the second time I went out with him, I discovered that the quad would still vibrate. It turned out that if the quad had any sort of loose screw, it would start to vibrate again. So, I guess like a high performance sports car, everything needed to be tightened perfectly for it to work. I didn't really like how finicky the frame needed to be because I wanted the frame to be as practical as your typical "flat-armed" frame. So I decided to make a optional brace for the quad (optional, as in, your quad will fly without it fine, but the brace is recommended).
I also decided to design a gopro mount specifically tailored to the frame. This little add-on was particularly cool because it was the first thing I printed from solidworks. Much thanks to VaskoFPV for helping me print the mounts!
After receiving the braces, the quad was rock solid, and ready for beta testing. I sent out a post asking for anyone who wanted to test.
I quickly had four great people contact me who were extremely generous in covering the machining costs! The frames were sent out in about a week and the beta team started putting the frame together. They quickly noticed some things right after assembling the frame, such as poor carbon tolerances, parts that didn't fit well, and a complicated assembly process. I wrote down all of their great ideas, and they began to put various components on their frames and fly them one by one. It was awesome seeing my design in someone else's hands for the first time!
After a couple mouths of betatesting, the team and I settled on a final version (or so we thought). I was amazed at how much more difficult the testing process was than I previously imagined. The combination of waiting for prototypes to be made, and being diligent on making changes made everything take forever, but I guess it also introduced me to the pains of R&D.. Nevertheless I had (and am still having) an awesome time with the group. Amazing guys. After the betatesters had spend considerable time on the frame over the summer, I started making the major edits.
First, the arms were made longer, since every one of the beta testers agreed that the prop clearance on the top plate was too little. The only solution was either to make the frame a squished x by moving the motor mounts to the other side of the arm, or extend the arms. I chose to extend the arms because that seemed like a more logical solution.
Second, the way the top plate was held on -- with two screws only -- seemed weak, and was also hard to access for repairs. Kevin (Quadview) pointed out that the screws that secured the standoffs onto the bottom plate intercepted the arms, which made it a pain to tighten the standoffs or put them on without disassembling a portion of the frame. His suggestion was to move the screws outside of the x shape of the arms, and have the central brace screw through the bottom plate into the two standoffs like this:
Additionally, there were many things about the frame that screamed "prototype" and "unfinished product." Inaccuracies in the carbon fiber, sharp edges on the aluminum, and unrefined shapes didn't add to the attractiveness of the frame that I was aiming for. The style and general aesthetics were unrefined as well, so that needed some work.
Finally, another one of the major issues with the frame was its weight. An AUW coming in at over 100g was sub-optimal, and I need ways to get the frame to be lighter. I had already edited the central braces to save weight, but the motor mounts were still clunky and round. After a complete re-do of the aluminum motor mount I came up with this.
I also edited the general aesthetics of the frame to make it a more finished looking product:
Now that everything was finished and ready to go into production, thus began the long search for a viable manufacturing solution. For carbon fiber, I knew that I would be using CNCMadness because I had already been working with him for a long time and didn't feel that I would be right to just abandon him (he also does a really great job!). The most difficult part would be finding an aluminum manufacturer. I originally thought that the parts would be cheap to make, but the more I talked with machine shops, the more apparent it became that machining aluminum would be very difficult.
My first thought was to go look at some US based shops such as protolabs. I felt confident that the prices would be manageable as I was uploading the parts, but when the quote was emailed to me, I was shocked. At over $100 per brace/motor mount for 50 of each part, how could I ever make this frame? How could such a small piece cost so much? And if so, how did other companies manage such high costs while selling their product for so low? I thought that protolabs might be an anomaly so I started to look for cheaper companies not based in the USA, thinking that Chinese companies might be cheaper. After searching around on Alibaba for a while and sending messages to various companies offering machining services, I was contact by one who said that they could do it for 5$ a part. I was elated! That was the perfect price. We conversed for a while getting everything ready to be machined, and then she sent me the quote after around 2 weeks of interaction... Well, it was actually $50 a part if I wanted 50, not $5. I went from feeling like production was within my grasp to feeling completely at a loss for what to do. I was stuck in a difficult position: I was a very small business wanting to sell an expensive product, however, if I wanted to make the product in the first place I would have to make a lot of that product. Being a small company, I wasn't sure I would be selling the hundreds of kits necessary to make profit from the costs of producing the frame, so I found myself unable to justify making the frame. Moral low, I decided to try one more option: look for smaller companies that do work for smaller businesses. I quickly began working with a cnc company that specializes in making small quantities of parts for small businesses. We conversed by email about possible prices - ~$10-20 per part - and I was hopeful once again. However, the more we talked about the actual production, the more expensive the parts became. Tapping holes and finishing the product gradually increased prices. Eventually, the final quote was 18$ for each brace, and 21$ for each motor mount if I wanted to make 50 braces and 100 motor mounts. Increasing the amount of parts made only reduced the price by around $5, but I wasn't sure I would initially get enough orders to justify manufacturing many frames. The price was significantly lower compared to the other companies I had talked with, but the prices were still simply too high. One frame would cost around $130 before any profit, which was an impossible price to sell, especially considering I was such a small and unknown business. Nobody would want to invest that much money into something that meant to be crashed and flown over 80 mph. I was officially stuck in the mud. Now that aluminum was out the door, I was unsure about the future of the frame. If I couldn't get the aluminum parts made, the frame wouldn't work! Everything was set up perfectly to be manufactured, but the price was just too high. Aluminum was too complicated, and I had to sadly scrap it. Therein lies the the lesson I learned about production.
Around the same time, I had just bought a ShenDrones Rapture frame to build up. A longtime admirer of Andy's designs, I had always wanted to purchase one of his frames. The rapture was very interesting. It used the very new HP Fusion technology to print its aerodynamic shell instead of a typical 3d printer. The Fusion printer used a new special material that was supposed to be incredibly strong and cheap to make. After learning more about this material, I became very intrigued. Would this material work instead of aluminum?! I was very excited. I had possibly just found the solution to my aluminum problem. The Fusion material supposedly combined the best of both worlds -- the strength and durability that I needed with the ease and cost of 3d printing.
In order to get the parts ready for the Fusion printer, I had to change many things on the parts to optimize them for a more flexible and slightly weaker material. I also could stylize and smooth out the parts, as I had reduced them to the bare minimum to reduce costs for the aluminum machining. With the Fusion printer, all shapes, curves, fillets and chamfers were possible, so I could make a very finished looking part, unlike the cnc machine which could only work on certain axes at a time -- adding more complication only added cost. There really were not any limits as to what I could do with the printer.
I changed the brace so that I was thicker at crucial joints and stress points:
And I changed the motor mount so that It would be strong enough to withstand a crash. Since there was also a right and left motor mount previously because there were two orientations for it, I combined the right and left motor mounts into one that could work as both to reduce costs and replace-ability if they break (no need to worry about not having the correct motor mount):
I sent parts to shapeways to be made and received them quickly. Each motor mount was $10, and so was each brace. However, protolabs offers bulk orders, so I can reduce the price to $6 per part for production.
The parts were beautiful. Very strong, yet flexible where they needed to be. The "tapped" holes also worked well, although I will need a bolt for some of the crucial holes. I was sure that this was the solution. The central brace was plently strong, and would also be aided by the side braces. A couple hammer tests with the motor mount proved that it was certainly strong enough (broke it only after removing its support screw and smashing it 7 times in a row.. with the support screw it's very strong) The parts were also very light, each of them weighting 3 grams. A major success was the final 74g weight of the frame. That brings it down into the racing class weight.
Here is a pretty picture of the final frame:
I am proud of the work that went into this project. I have successfully implemented my own ideas to reduce surface area beneath the prop disk (a proven, beneficial factor to miniquad flight) in a durable, lightweight form that is cost effective and repairable. Head over to my store to purchase one. Sales are going well so far!
Current Status: Lets get some orders!