One way to enhance the pictures taken by a camera rocket is to add a mirror that looks down the side of the rocket. This lets you take stunning liftoff shots and because part of the airframe is visible in the shots adds some perspective to the pictures. Now you know they are taken from a rocket! The mirror assemblies I have experimented with are fairly simple designs.
For AYUCR I made two mirrors. The first of the two was a bit too small and not at the proper angle. I assumed originally that 45 degrees would work best but that gives a bit too much of the rocket body in the shot. You want some of the rocket to show but not dominate the frame. I have settled on 50 degrees as optimal. Both mirrors for AYUCR were made by making a balsa frame and filling them with epoxy. I did this by affixing waxpaper to the body, holding the frame to the body with rubber bands and pouring epoxy into the frame. While this made the mirror assembly conforms nicely to the airframe it weighed alot and I almost had a disaster with the tremendous heat generated by this much epoxy curing. Don't make your mirror this way.
For AYUCR II I made a mirror out of a block of balsa shaped on a disk sander. I attached sandpaper to a piece of tubing to sand the bottom to conform to the airframe. The balsa mirror assembly is coated with a layer of 1/2 oz fiberglass to make it more durable. This is a much better way to go. The assembly is lighter and it took less time to make. The mirror itself is attached using epoxy. For the mirror itself I am using a piece of standard mirror glass. A first-surface mirror would be better but I have gotten good results with a standard mirror.
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| Mirror is attached with epoxy | Notice the contour to fit on the airframe | The screws are for the retractor |
Retractable Mirror
One thing I don't like about my design is the mirror isn't actually big enough. One edge of the mirror is visible in all of the shots. This is disorienting because you see what the camera sees straight ahead and down in the same shot. The solution obviously is to make the mirror bigger but I am reluctant to do that for aerodynamic reasons. The other solution is to make the mirror retractable so it is used for boost shots where it is the most useful and then retracts out of the way for descent. I think I have finally come up with a good way of doing this. I simply placed a slot in the airframe ahead of the lens hole. There is a screw on the bottom of the mirror assembly that rides along this slot. The screw keeps the mirror attached while the contour of the mirror and the airframe keeps it aligned. I use a rubber band to provide the retraction action and a piece of kevlar thread to hold the mirror in place under boost. At separation the thread is released and the mirror pops forward out of the way. That's the theory anyway. I'll have to report back on how it all goes. If I really wanted to go nuts I might connect it all to a servo and have the camera timer control it...
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| Screw rides in slot in airframe | Slot for mirror forward of lens hole |
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| Retractable mirror with kevlar thread holding it in place | After separation rubberband retracts mirror |