Friday, January 20, 2012

Old Plane New Life

Hello all,

I've got an old plane that is in need of a new life.  I received this really cool RC airplane several years ago as a gift.  It was cool because it looked like a jet with a motor mounted on the rudder, and it came with a mini digital camera that was activated from the transmitter!

The biggest problem with this plane was that the control system was not proportional.  This meant that the elevator and rudder were at neutral or full up or down.  No where in between.  The motor did have three speeds, but if it's too hard to fly, the throttle speeds do not matter.  After many attempts to fly and very little success, I packed it away (I'm way too cheep to through out something like this).
Original plane and transmitter

Now I'm back into RC flying and it's time to see what can be done with this thing.  I hauled it out and started to take it apart and see what was worth keeping.  I had high hopes for some micro servos, if not a small receiver or speed controller.  As it turns out the servos were just a motor with gears so they were out.  The receiver was this awkward and large conglomeration that incorporated the speed controller.  So, nothing but foam was salvageable.

I started by gutting the whole thing to see for sure what I had to work with and where things might go and how I might put it all back together.
Gutted plane showing compartments

All the pieces
Before I had plans for the rest of the plane, I knew that I wanted to put ailerons on it.  So that is what I started with.  I decided to do this because I will be using the old 3 channel transmitter and receiver from my Wild Hawk.  I had great success using just elevator and aileron controls on that plane and thought it would be a good idea for this one as well.
Ailerons installed and servo locations marked out
Servo location cut out
Servo dry fitting
For this build I decided that I could just cut right through the wing and install the servos there.  The close tolerance of the cut out will hold the servo from moving and then tape on either side will secure it even more.  Taping it like this will allow for easy access when needed.

View from the back side

Servo cable routing
So far so good.  Now I need to look at how to control the elevator.  The plane is too small and light to mount a servo in or even near the tail.  Plus with this plane having the motor mounted so far back, I don't want to add any more tail weight.  I decided on a location under the wing and made a cut out for the servo.  This time instead of actually cutting the foam out, I melted the foam with a solder iron until I had the shape I wanted.  Doing it this way gave me a rigid compartment for the servo.
Original servo in place

New servo.  Fits perfect
At this time I also ran two bamboo skewers down the middle of the fuselage to give it more rigidity.  I used my solder iron to channel out any places that needed it to make room for the skewers.  I used hot glue to hold the skewers in and they made a big difference.

Both aileron servos in place
After getting the servos and re-enforcement in place, I think I'm ready for assembly.
All pieces ready to put together
I think it looks good!  You can see that I soldered the speed controller connection along the outside of the fuselage to the motor.  I was going to try to route them inside, but that was going to be too much trouble and this will work fine.
All together from the top side
This is the underside where you can see that after I inserted the speed controller and receiver, I just taped over the opening to hold it all in.  The battery is installed in the compartment under the front wheel.  There is also an on/off switch located there that I re-used.  It's really small but works fine.
From the bottom side
Now its time to align the servo arms, control linkage, and control horns.  I don't have my servo tester yet and did not use the radio to center the servos.  I just assumed that they were centered and installed the servo arms where they needed to be.  Then hooked up the push rods and connected to the aileron horns.  Once this was done I fired up the radio.  Wow!  I almost ripped of the left aileron!  That will teach me to assume and not check everything before I just put it together.
Miss aligned servo almost rips aileron off
Now everything is together the way I intended and everything has been tested.
Ailerons aligned properly
Everything is ready for a test flight and as usual, I'll have to wait for an the alignment of the stars, well, good weather and free time.

Thanks for stopping by my blog.  Please feel free to post comments, good or bad, and be sure to come back and check for future posts.

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Mr. Clean