MD500 Tow Defender Build Page 4
FLIR Mounting and Control:
I wanted the FLIR on my Defender to rotate automatically. I was going to use light sensors and have it follow shadows or bright spots, but then I decided on an auto mode. The FLIR will move with simulated random movements. The movement is controlled by a custom circuit I designed using a PIC12F629 microcontroller. There is also an on/off control for the FLIR in case I want to shut it off sometimes. The FLIR controller just plugs in series with the servo used for rotation. See the electrical section for more details.
First I needed to cut a hole to get access to the inside of the FLIR assembly. On the bottom of the FLIR I was
planning on using an pogo pin (used on electric test fixtures) to provide the bottom rotation point, and to put a constant
pressure pushing upwards to reduce vibration. To mount the pogo pin I planned on pushing it into some basswood that
I would epoxy in place. This photo shows a stick putting pressure on the basswood while the glue dries.
I had decided on using an airplane steering arm to connect to the FLIR housing to a shaft that would come
from inside the fuselage. So I epoxied it in place the arm in place. Ah, this is working great I though to myself.
Once again my idea did not work as planned. I have just has a lesson in using epoxy to glue to fiberglass (doesn't work).
Looks like I will have to come up with a plan 'B' for this phase of the build also. I am going to be pretty good at plan 'B' options
by the time I am done with this build I think. LOL!!!
I got it I thought to myself. I am working on fiberglass so I should use fiberglass to glue to fiberglass. So off I went to
the local NAPA store to buy what you see pictured here. I am thinking I am pretty smart now, he-he...
So now I mask off the front because I am sure that some fiberglass resin will get on the outside of the FLIR module if I don't.
Sure enough the tape saved my butt as you can see in the photo that resin did get on the sides. It was very hard to work through
that stinking little opening. Now I just wait for all this work to dry. So off to something else I go.
(What I did learn later but I will write here is this, the steering arm works very well without any bottom support. So I scrapped the pogo pin idea all together)
I have the FLIR in place and a bolt going through the fuselage into the top of the FLIR steering arm. I ended up using two screws to
hold the steering arm in place inside the FLIR (no photo, sorry). On the inside of the fuselage I use a second steering arm to connect
to the screw from inside the FLIR. Now if the wire you see is moved, the FLIR rotates. It's like magic. It actually works very well.
I made a mounting plate for the servo which is secured to the FLIR mount from outside. The LFIR hides the screws so no one will know
how it's mounted. Only bummer is that the plate will have to be removed if the servo goes bad because the servo is under the front of the
fuselage windshield area. Not that big of a deal though as I have only had servo go bad in all my years in RC.
Because I don't want the FLIR rotation servo visible I am building a compartment for it to reside in. It is made of basswood, plywood, and
balsa wood. There will be an access panel that can be removed if needed to get at the servo for repair/replacement.
This is a side mounting flange for the FLIR compartment cover to screw to. Using JB Weld for glue
here as it seems to work with fiberglass. Just have some weight on it while it cures.
FLIR access panel screwed in place and waiting to have the right side of the assembly glued in place.
Top view of the FLIR servo in it's compartment. I will be making a top that will attach to the removable panel.
The top is made and glued to the front removable cover.
Using hysol 9462 to glue this side panel in place. This glue works great with fiberglass.
Something I learned from the Scale RC Heli forum.
Here's a view of the flange and side glued in place.
Below is a demo video I made showing how the FLIR will move.