Project:
R/C Airplane ATV Video Pod
Designer(s):
N8QPJ
Description:
The idea for this project came about after an ATV (Amateur Television) presentation at an Amateur radio club meeting. After the meeting a person (Mike) approached me and asked if I tried ATV from an R/C plane. I said I didn’t know how to fly an R/C plane. Mike offered to help me learn to fly. So I set a goal to learn to fly and put an ATV transmitter on an R/C plane before the end of the year, it was May. By mid June I bought an R/C plane and all the other stuff needed to fly. I joined an R/C flying club and hooked up with an instructor to teach me how to fly. In July Mike and I met at the flying field. Both of us brought enough ATV gear to put together a package for his R/C plane. We used rudder bands to mount the camera, transmitter and battery pack to the plane. Mike took the plane up and flew it around for a while and landed it safely. We reviewed the tape and the video came out ok but it was very shaky. The test was a success but we needed to reduce the vibration and improve the video signal. By mid August I earned my Pilot patch. I was an R/C pilot! By mid October it was time to test my version of the ATV pod. The pod worked better than expected. The video from the plane was great.
Now down to the business of designing the ATV system for my R/C plane. The system had to be light, produce good video without vibration and be moved from plane to plane easily. The ATV pod seemed to be the answer.
Technical Information:
The ATV pod had to be as small as possible and weight less than a pound. Before building the ATV pod I had to acquire the parts that would go in the pod. The ATV transmitter is a modified (10db pad removed) Wavecom 2.4Ghz FM unit. It is small, light and will work on 8.5 volts DC. The camera is a small CCD B & W board unit (1.25" x 1.25"). It will work on 9.0 volts DC. The antenna is a custom made 2.4Ghz sleeve dipole rubber duck with a SMA connector made by Mobile Mark. It is 5 inches long. The battery is a custom made NiMH ½ AA 8 cell 9.6 volt 600ma pack by E. H. Yost (Mr.NiCd). It weights 4 oz. The SMA connectors were bought at a Ham swap and The RF Connection. The RG-174 Teflon coax came from my junk box. The Morse CW id board is an ID-8 from Communications Specialists Inc. The ID-8 continuously sends my call sign on the audio channel of the 2.4Ghz ATV transmitter. Now that I had all the parts, I laid them on a sheet of paper in the position they would be in and drew an outline of what the pod would look like. The pod is built of 3/32" R/C aircraft Lite plywood and 30 minute epoxy. Two quarter inch hardwood dolls provide attachment points to rubber band the pod to the plane. 1/8" clear Plexi glass was used for the camera window and the antenna mount. After the pod was built and painted with white urethane enamel paint the parts were placed in their compartments and wired together. The power switch was mounted on the side of the pod. After testing the completed ATV pod each part was wrapped in ¼" latex foam rubber. For the camera I made a mount out of 2" dark gray soft foam to prevent vibrations and reflections. The Plexi glass camera window is held in with 3M 35 electrical tape to allow for quick changing if the window is damaged. The light level going into the very sensitive camera had to be reduced to produce a good picture. A piece of a lens from some cheap sunglasses worked well. ½" latex foam rubber was placed between the ATV pod and the planes under belly to reduce vibration. The total weight of the ATV pod is 13 oz.
With the ATV pod completed it was time to think about the receiver setup. The receiver is a slightly modified (patch antenna replaced with a female BNC connector) 2.4Ghz Wavecom. The receiver antenna is a Directive Systems 9 element twelve inch long loop Yagi with 13dbi gain. I mounted the loop antenna to the Wavecom receiver. A 12 volt gel cell powers the receiver. If I didn’t have a helper, how would I keep the receiver beam antenna pointed at the plane? A plastic hardhat with the 2.4Ghz receiver and loop antenna mounted to the hat and the 12-volt gel cell strapped to my waist solved that problem. A 50ft piece of very flexible RG-59 video cable connected the 2.4Ghz receiver on my head to the TV/VCR for recording. Despite the strange looks from people at the flying field the hat setup kept the receiver antenna always pointed at the plane.
The R/C airplane used to carry the ATV pod is a Thunder Tiger 60-size trainer with a 72 inch wingspan and an OS 61 Fx motor. The stock wheels were replaced with 3 ¼ " wheels for more ground clearance for the ATV pod. The stock nose wheel strut was replaced with a dual strut assembly for more stability on the ground. The R/C radio used is a Futaba 50Mhz 6-ch. FM unit with a 50Mhz PCM receiver in the plane.
Hardware:
Approximate cost of ATV pod and Receiver setup $450
Hardware Sources:
Conclusion:
This project took a great deal of time and patience but after seeing the video from the plane come in clear and stable it was worth the effort. Learning to fly a R/C airplane was a great experience. Combining Amateur Radio and R/C planes added much more excitement to both hobbies. Soon I will replace the B & W camera with a color camera and I am also thinking of designing and building a R/C plane with a pusher prop so I can mount the camera in the nose for a better view. If you are an R/C pilot who is thinking of trying video from the plane you will need an amateur radio license. Just as R/C pilots help out student pilots to fly, amateur radio operators help others get their ham license. You don’t have to learn Morse code to get your license. There is an Amateur Radio Club near you.
- Jeff Basting N8QPJ
Fig 1.0 - 60 size RC plane with video pod
Fig 2.0 - 2.4 GHz ATV pod mounted to the plane
Fig 3.0 - 2.4 GHz hardhat antenna/receiver
Fig 4.0 - Fraser flying field from 250 feet
Fig 5.0 - RC Flying formation!
