RC Parafoil Project

RC Parafoil Project

          The purpose behind this project was to create a simple and easy to build electric powered remotely controlled parafoil that could be used to record low oblique digital aerial images of a specific location (Centre of Geographic Sciences, Nova Scotia, Canada). Having no real RC model aircraft experience I set out to design a system that would be easy to build, stable in flight as well as on the ground, and have the ability to carry additional sensors. I wanted something that would be slow and stable, easy to transport, and relatively easy to fly, so a powered parafoil sounded like the right choice. While this project was considered a success and it did deliver the imagery I needed, I wouldn't say it is the most efficient thing flying. It is easy to fly and simple to build but it tends to plow through the air instead of flying effortlessly.

          The system shown here may not be the most sophisticated but it does fly well and it accomplished the task at hand. After receiving numerous inquiries from other researchers about the design and performance of this system I decided to create this site in hopes it will be useful for those who might want to build a similar system. Because I'm not an aeronautical engineer or an RC enthusiast this design may not be perfect but it is simple to build, does the trick, and really fun to fly.

          What are the flight characteristics you might ask? Well it gets airborne in less than 10 metres, flies straight and level at about 30% throttle, has a wide and slow turning radius, and returns to a safe glide when the throttle is cut back. One unique flight characteristic (which is common in most parafoil designs) is the tendency for the gondola to pivot skyward if the throttle is applied too quickly. In fact, the motor has so much power the system could flip itself upside down if to much throttle is applied (not a good thing).

          The best method of flying this system would be to keep your throttle and steering actions smooth and gentle. One other important consideration would be the ambient wind speed. Because this setup is relatively large and it flies somewhat slowly, the system doesn't like to be flown in high winds. The calmer the conditions the better. Besides having a hard time working its way upwind, you will have a tricky time keeping the parafoil from blowing around before it gets airborne if you attempt to fly in windy or gusty conditions. I find early mornings are often good times to fly this system.

          You might wonder why the steering system looks like it does. Well, I wanted to make a system that was compact and robust and I wanted to make sure the weight of the gondola wasn't resting on the servo. So I thought of having the upper steering plate pivot on a plate that would support the full weight of the gondola and have the servo move the arm in a way that wouldn’t transfer the full weight of the gondola to the servo. The important aspect of this system is the servo’s axis of rotation be aligned with the steering arm’s point of rotation. This may not be the most elegant system but it seems to work well. I chose to go with a standard high quality stunt kite for the parafoil and this choice seems to work fine.

          I chose the GOPRO HD camera system because of its good quality wide angle lens, it’s light and durable, easy to attach to the airframe, and can record both HD video as well as 5 megapixel still images (which is the option I used). I set the camera to record one image every second and then sent it aloft. Without the aid of a video telemetry system (which could be added) the wide angle lens becomes very useful when trying to position the aircraft for the image. You will end up deleting most of the images but if you're things work well you’ll come back with some nice shots of your area of interest. The sample images below were recorded during a short 3 minute flight (and remember I have almost no RC flying experience). So, if I can do it, I bet you can also.

          Again, I've placed these images and diagrams on this site because many have inquired about the project and wanted to see more details. By no means do I consider this to be the best or most efficient design for such a system but it does seem to work well, is easy to build, achieved the results I wanted, and is great fun to fly. If you have never built or flown anything like this it would be a great idea to contact your local electric RC aircraft model club to see if anyone would be interested in helping you with your project. It's always great to seek out the advice of experienced builders and pilots when attempting a project like this.