FunktheEngineer
Junior Member
I have been a passive FT community member for about a year now. I have built several planes from FT designs and at the beginning of the summer, decided I wanted to try building a C-130. Shortly into the design process, I decided to scale back my ambitions and build a twin engine aircraft instead of trying to integrate four engines for my first multi-engine build. HobbyKing had just released the SkyMule and I decided to scale that up a bit and thus the SkyDonkey was designed.
At first, I wanted to write an article about my build but the more I listen to the Podcasts about article requirements, I decided I throw my experience here on the forum and do a better job documenting for my first article in the future.
Once I decided on a aircraft, I took the pictures posted on HobbyKing and did some quick measurements and scaled the fuselage up about 50%.
As far as build techniques, I used a bunch of A and B folds, hot glue, and few integral ribs.
For the tail, I wanted to keep things easy so instead of trying to hide the servos inside, I just cut them into the top surface of the fuselage.
One of the things that I wanted to include was some sort of drop door. Having no experience with how this is done, I used a small cabinet hinge and two servos. Technically, I know this is bad form because any down load on the door from whatever I put inside is putting strain directly onto the servo. But until I learn better, this is working well so far.
For the wing, I used a scaled-up version of the FT Duster wing. Unfortunately, I didn't take any pictures of the wing before I fully assembled it. The wing itself is 3 pieces of foam board. Along with the standard Duster foam spar, I added two .5" diameter, 60" long carbon rods into the wing - one just inside the leading edge and one tucked as close to the trailing edge as possible.
For the engine mounts, I used shorten versions of the FT swappable power pods. The engines are mounted to a plywood firewall and the esc's are located inside the pod. I added air-scoops to the sides of the pods and put a hole in the back of the pod to increase airflow across the esc.
The electronics gave me problems. It took me a little while to figure out how to get two motors to talk together the right way. My brother-in-law talked to me about incorporating differential thrust but that might come later. The biggest problem I had was matching my motors to esc's. I chose the HobbyKing Donkey ST3007-1100kv motors and I started with a pair of HobbyKing 40A esc's. I don't know if they were bad or what, but I couldn't get the system to initiate. So I replaced the esc's with a pair of HobbyKing Red Brick 50A esc's. Now I could get the system to come on, but the motors might have both come on for a few seconds and then they would stop and rotate back and forth and then nothing. It was very weird and the project stalled a few weeks because I just couldn't figure out what was wrong. I could hook one motor up to a small esc and it would work. Then I could hook up one of the esc's to another motor and it would work. Finally, I decided to try yet a third pair of esc's. For the final try I chose the Birdie 50A brushless esc's. I got everything connected and both motors fired up first shot. For the props, I decided to use opposing 11x7 3-blade Master Airscrew props.
One of the biggest under-designs of the project was the nose landing gear. I started off with a tail wheel assembly from a Horizon Hobby Corsair and I put a bigger wheel on it. When I did some taxi testing, it was way to weak and any time I throttled up, the aircraft just nosed into the ground. So after beefing up the nose gear (probably too far the other way) here is the assembled aircraft.
I have a GoPro 3 white that I have mounted statically on several planes but I have increasingly been contemplating FPV. In one of my orders to HobbyKing I found an inexpensive pan/tilt gimbal so I added that to the nose of the aircraft. Now, when I assemble the correct FPV gear, I'll have a good platform.
I was nervous when I finally was out for the maiden flight. I had started the project in June and it was now September and I really didn't want to crash - which I have a really bad habit of doing. It was a nice day and none of my flying buddies were available so I was in charge of both flying and filming. Here is the result.
http://youtu.be/vX2nj_HFvEk
I was actually very happy with the result. It flies super smooth and didn't require too much trimming. I am really excited to get this aircraft out more and start having some fun with it. The nose gear still needs a little more help. The way I attached it to the foam worked great on the workbench but I will end up adding some wood reinforcements. Also, I have some parachute men in the mail that should be fun to drop from the rear door.
Thanks again for reading and feel free to ask any questions. I look forward to becoming a more active member of the FT community.
At first, I wanted to write an article about my build but the more I listen to the Podcasts about article requirements, I decided I throw my experience here on the forum and do a better job documenting for my first article in the future.
Once I decided on a aircraft, I took the pictures posted on HobbyKing and did some quick measurements and scaled the fuselage up about 50%.
As far as build techniques, I used a bunch of A and B folds, hot glue, and few integral ribs.
For the tail, I wanted to keep things easy so instead of trying to hide the servos inside, I just cut them into the top surface of the fuselage.
One of the things that I wanted to include was some sort of drop door. Having no experience with how this is done, I used a small cabinet hinge and two servos. Technically, I know this is bad form because any down load on the door from whatever I put inside is putting strain directly onto the servo. But until I learn better, this is working well so far.
For the wing, I used a scaled-up version of the FT Duster wing. Unfortunately, I didn't take any pictures of the wing before I fully assembled it. The wing itself is 3 pieces of foam board. Along with the standard Duster foam spar, I added two .5" diameter, 60" long carbon rods into the wing - one just inside the leading edge and one tucked as close to the trailing edge as possible.
For the engine mounts, I used shorten versions of the FT swappable power pods. The engines are mounted to a plywood firewall and the esc's are located inside the pod. I added air-scoops to the sides of the pods and put a hole in the back of the pod to increase airflow across the esc.
The electronics gave me problems. It took me a little while to figure out how to get two motors to talk together the right way. My brother-in-law talked to me about incorporating differential thrust but that might come later. The biggest problem I had was matching my motors to esc's. I chose the HobbyKing Donkey ST3007-1100kv motors and I started with a pair of HobbyKing 40A esc's. I don't know if they were bad or what, but I couldn't get the system to initiate. So I replaced the esc's with a pair of HobbyKing Red Brick 50A esc's. Now I could get the system to come on, but the motors might have both come on for a few seconds and then they would stop and rotate back and forth and then nothing. It was very weird and the project stalled a few weeks because I just couldn't figure out what was wrong. I could hook one motor up to a small esc and it would work. Then I could hook up one of the esc's to another motor and it would work. Finally, I decided to try yet a third pair of esc's. For the final try I chose the Birdie 50A brushless esc's. I got everything connected and both motors fired up first shot. For the props, I decided to use opposing 11x7 3-blade Master Airscrew props.
One of the biggest under-designs of the project was the nose landing gear. I started off with a tail wheel assembly from a Horizon Hobby Corsair and I put a bigger wheel on it. When I did some taxi testing, it was way to weak and any time I throttled up, the aircraft just nosed into the ground. So after beefing up the nose gear (probably too far the other way) here is the assembled aircraft.
I have a GoPro 3 white that I have mounted statically on several planes but I have increasingly been contemplating FPV. In one of my orders to HobbyKing I found an inexpensive pan/tilt gimbal so I added that to the nose of the aircraft. Now, when I assemble the correct FPV gear, I'll have a good platform.
I was nervous when I finally was out for the maiden flight. I had started the project in June and it was now September and I really didn't want to crash - which I have a really bad habit of doing. It was a nice day and none of my flying buddies were available so I was in charge of both flying and filming. Here is the result.
http://youtu.be/vX2nj_HFvEk
I was actually very happy with the result. It flies super smooth and didn't require too much trimming. I am really excited to get this aircraft out more and start having some fun with it. The nose gear still needs a little more help. The way I attached it to the foam worked great on the workbench but I will end up adding some wood reinforcements. Also, I have some parachute men in the mail that should be fun to drop from the rear door.
Thanks again for reading and feel free to ask any questions. I look forward to becoming a more active member of the FT community.
