Picture by Peter McCulloch

Nothing terribly innovative here, a standard double U rig, the basic design is covered in the excellent resources in www.kiteaerialphotography.net and numerous other places on the Web and The Aerial Eye. What I've attempted to do here is detail aspects of the construction that are either novel, or poorly covered elsewhere. There is also an image taken by the rig on this page, and a Gallery of images taken in 2003, when the rig flew.

As well as the rig you also need some ground equipment, a kite, a suspension system, and the ability to stay cool when behaving strangely in public.

The Rig:

• Nikon 775 2Mpixel camera. This was chosen because of its availability :-), its low weight, good optics, and features including auto power-down, re-activated by pressing the shutter, and video output. 
• Micron build your own model RC receiver. Chosen for low cost and the fun of making it myself. They also have kits ideal for making into a KAP transmitter, everything you need without the joysticks and case, just what the KAPer ordered!
• VideoLynx micro TV transmitter. Chosen because I am a radio amateur and this route was recommended on other web-sites as the best for a good strong picture. This transmitter is completely sealed which also made it good for KAP. Aerial is a ¼ wave radiator and ground plane connected directly to the transmitter.
• Batteries: 5x NiMH 3/4 AAA from Strikalite, 9g each, 350mA/H. For windy days 5x NiMH AAA from Strikalite, 13g each, 700mA/H. Alternate emergency batteries 4x AAA Alkaline, 13g each plus holder.
• Tilt uses a standard servo, Pan uses a standard servo with the feedback pot mounted externally via 4:1 gear reduction. Since the transmitter is custom designed and could be adjusted, there was no issue with servo travel only being 80^o. In fact the tilt servo moves 100^o giving a small overshoot, allowing you to look "up". Control of the shutter uses a micro servo with a string from the servo near the base of the camera up and over the shutter button, The zoom is also controlled with a micro servo and paddle located beside the zoom buttons. I did take the Nikon apart to look at electronically activating the shutter and zoom, but the camera inside was far to "busy" for me to attempt this. I also investigated controlling the camera via USB, but this was only available on the heavier Nikon 885. I couldn't find any pages where the USB had been cracked by hackers but I'm still convinced the functionality is there, just disabled. Anyone work for Nikon reading this?
• Rig weight 310g (11oz). Total laden weight: rig, camera, memory card, and batteries is 550g (1lb 3½oz)

The Good Bits:

• Centre of Gravity: There didn't appear to be good web coverage about this so read this page for an exposé on keeping your balance!
• Video Switch: To save power (and weight) the video downlink is disabled when the camera is in sleep-mode, this page tells you how.
• Additionally drawings of the construction are contained in this 6 page document.

The Bad Bits:

The experiences I learned whilst building the rig are detailed here (There are further Learnings that were made during the first year I flew the rig):

• The Nikon 775 (along with much consumer electronics) generates a lot of electrical noise. Accessory leads contain ferrite rings to try to cut this interference out. Unfortunately to save weight I cut out the ferrite rings:-). By experimenting I re-instated the ferrites that were "making a difference". I also added a ferrite to the supply for the Downlink transmitter to stop it interfering with the Servo receiver. There is a fuller explanation of how to handle Electro-magnetic Compatibility (EMC) issues.
• On first flight the connection between the picavet and rig worked loose. This can be very dangerous and lead to the camera being dropped. Fortunately a small safety pin through a hole in the shaft stopped the connection coming completely loose! A small plastic block was glued to the picavet to prevent it rotating by locking it against the M4 nylock nut the wing-nut bears against.
• The Casio TV used for the video downlink is difficult to see in sunlight. A black plastic hood was made for the screen from a small plastic box, and fixed with elastic bands.
• To avoid picture blur you need to get the shutter speed up. Most digital cameras are ASA100 equivalent, and this doesn't help. I run the Nikon 775 in PORTRAIT mode, which ensures minimum F stop and highest shutter speed, at the expense of having the focus motor "hunting" all the time, which reduces battery time. Even with that the shutter speed can be as low as 1/125 which is marginal. >=1/500 is ideal. The best digital camera for KAP doesn't exist currently since high resolution, high sensitivity, sensors are currently only used on top of the range, heavy SLR type camera bodies.

The Results:

Avon Aqueduct, Union Canal, near Linlithgow from Muiravonside Country Park. Scotland's longest aqueduct. 

The original is a stitch of 2 x 2Mpixel images, 1st February 2003.

After a Summer of operating this rig I had learned some lessons!

James Gentles March 2003 HOME PAGE KAP HOME PAGE