Motivation
Months ago, I bought a cheap, (£20) Fuji Nexia camera expressly for use as a means of getting aerial photographs using my model aircraft.  For a year or more I have been looking at some superb results obtained by guys who have trodden this path before me.  Their pictures had made me eager to get some of my own.  However, I wanted to build a camera mount which would satisfy two of my own criteria.   

Design objectives
First, I wanted my mount to be a self-contained module so that second, it would be easily transferable from aircraft to aircraft.  For my first, trial “lifter” I use a model out of the Ben Buckle collection.  Though originally designed in the year 1937 and kitted by Keil Kraft in 1946, the 96 inch span Falcon should make a good carrier I thought.  I was right about that as the Falcon didn’t really notice the 11 ounce additional payload.  Little wonder if one looks at the airfoil and the chord which would probably hoist a Blackburn Beverley.  

Trouble anticipated!
The potential problem that I most feared was vibration.  My Falcon is powered by a very tasty Laser 70 but it has quite a lot of mass which rocks the airframe around the fore and aft axis.  As the Laser is quite capable of flying the Falcon at about 1/3 throttle I have no need normally to be running it at high revs but that makes matters potentially worse as the vibrating effect of the rocking couple on the airframe is then greater. 

Building the camera module
1. The first illustration shows the simple, 1/8 Liteply box which forms the basis of the carrier while the second gives a closer look at the joints used.  You might think that these are a fag to cut but they add considerably to the strength of the structure whilst keeping it light.  Don’t just use butt joints please!

2.  Essentially, this box will be mounted “in tension” between the fore and aft wing securing dowels on the port side of Falcon.  Slipped on to the wing rubber dowels before the wings, the rubber bands go on last making the module very secure.  I thought that this method of hanging the mount would go a long way to eliminating vibration.  I was wrong but more of that later!

3.  The Liteply has been reinforced where necessary and for that I used 1/32 ply.  Illustration 3 shows a reinforcing plate added to the rear, left-hand corner.  This handles the tension placed on the box by the metal strap shown below in illustration 4.  A second plate is glued on inside the box in this position.  Fabricated from a standard 2mm control link the strap requires on one end a hook which engages with the hole you can see in illustration 3.  Keep the thread at the other end of the strap for attaching a metal control link.  This allows for fine tuning of the length and hence the tension.  The link connects with a made up, small, aluminium plate in which I drilled a 1/4 inch (slips over rear wing dowel) and a 1/16 hole (for attaching the standard link).  

4.  The for’d anchor for the box is simply a 1/16 ply plate with a 1/4 inch hole for slipping over the for’d dowel.  This needs to be attached to the box with a small, wedge piece of balsa if as I did, you want your camera to look down at an angle - more of this later too.  Inside the box here I put another 1/32 ply disc.  I always over-engineer so I then put a 2mm bolt through this sandwich applying thread lock and using my Dremel I then cut the bolt off flush.  This method of suspension works magnificently if you award marks for swift, simple assembly coupled with security.  

5.  Illustration 5 shows a gusset plate added for one function only which is to give the camera a controlled, downward viewing angle.  In this picture you can also see the angle of the balsa wedge behind the for’d mounting plate.  As I used just one gusset plate (saving weight), I reinforced it with balsa quadrant stock and because I love making things in wood, I beefed that up with the piece of Liteply shown in illustration 6.  Using a razor saw I rebated the plate so that I got a very strong reinforcement by gluing it to the top of the gusset.  

6.  Illustrations 7 and 8, below, are of a “first fit” and you can clearly see how the box is suspended between the wing dowels. 

7.  I decided that the mount really needed to be steadied at right angles to the fore and aft axis and so I added two more circular ply plates through which I drilled 1/16 holes to take the wire frame that can be seen in place in illustration 9, left. This frame is also made up from a standard 2mm control rod.  I cut a 2mm thread on the blank end (they come with just one end threaded).  The purpose here was so that I could make some adjustment by tightening or slackening the nuts that would hold the frame through the holes in the ply plates.  A suitable thread cutter can be bought for a few pounds and it will prove to be very useful for many other little modelling jobs - Contact me if you wish to buy one but don’t know where you can.  If you wish, the frame could be attached by making large radius hooks on the ends before poking them through the locating holes.

Servo mounting
Illustrations 10, left, and 11, right, show that I made up a sort of horseshoe shaped mount for the servo.  This is secured by one socket head, 3mm screw.  On the inset in picture 10 the ply plate and the head of the socket screw are plainly visible.  Note the steel peg which locates the servo mount without the need for a second bolt.  See illustration 12 and 13, below,  for greater detail on the servo mount.  The more observant among you will note that I have now dispensed with the outer part of the mount and the servo is secured by one screw and the lightest of cable ties.  This arrangement has been adequate as the pictures will eventually confirm.