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.

Saturday, January 7, 2012

CG Finder

Hello all,

I finally decided that using my index fingers was not accurate nor useful enough any more and that I needed a better method to find the CG on my planes.  I checked out commercial CG finders with lots of cool options, but being the cheep Dutchman I am, I decided I could just make my own.  So, the following is the process I went through to make a CG finder.

CG finder pieces
I started by looking for a suitable stand.  I had seen others use a 2x4, but I did not want something that size.  I looked in my scrap wood bin (what do you mean you don't have a scrap wood bin?) and found a piece of primed trim about 3/4x2x12".  This seemed like it would work fine.  Then I looked for something for uprights.  Again to my scrap wood bin and I found some 1/4" wood doweling.  I cut two pieces about 10" long.  I then drilled two 1/4" holes in the base about 8" apart.  All of these measurements so far were just arbitrary and just guessing how much clearance I might need or want.  Enough rod length for fuselage body and landing gear clearance, and separation of rods for a suitable width.
 I wasn't to concerned with the size or stability of the base as it would be at, or close to, the CG or balance point and would not need much stability.
Rounded off rod tips
I did round off the ends of the rods a bit to provide for a smaller more accurate tip, but one that would not poke into foam or covered wings.

All setup
Setup it looks pretty good and works well too.  I did not glue in the rods so that I could take it apart for easier transport.  The pieces fit quite well in the upper tray of the little tool box to the right in the photo.

CG finder being used on my Wild Hawk

Using tape measure against rods
This little unit has worked quite well and for the money, you can't beat it.  Besides, it's really hard to take measurements with a ruler when the plane is balancing on your finger tips.

My conclusion, if you need a CG finder for your plane, just go out and make one!  It's real easy.

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.

Thursday, January 5, 2012


Hello all,

Since I now have a programmable transmitter and an airplane with ailerons in need of flaps, I decided to see what it would take to setup flapperons.  My initial installation of ailerons consisted of flaps cut into each wing with servo to operate each one and a "Y" cable to connect both servos to channel one on the receiver.  One servo was installed apposed to the first one so that they in effect move opposite of each other.  This proved to be a perfectly usable way to run ailerons and is easy to trim.  As there is no room to add flaps with another set of servos, it seemed reasonable to try setting up mixing to accomplish this.

Cutting out the Y adapter

Both connectors cut out

New aileron extensions installed
The first thing I needed to do was to cut out the "Y" cable that I had glued in.  Each of the split connectors were glued, one into a cutout in each side of the fuselage.  Once these were removed I replaced them with regular extensions.  One of these would go into channel 1 and the other would go into channel 6.  Channel 1 would then be mixed with channel 6 and channel 6 set for reverse direction.  Then switch B would be mixed with channel 1 and then again with channel 6.  Since channel 6 had been reversed for aileron control the mixing of switch B would also need to be reversed.

HK T6A V2 6 channel transmitter
As I have a Hobby King T6A V2 2.4GHz 6 Channel transmitter, this required the use of the T6Config software.  Now I have to say that this isn't the greatest software but it is functional.  The first time I used it, it worked just fine and I was able to reverse my elevator servo and play with a few other settings.  Well, that was some time ago and I have not needed it since.  This time when I started up the software I was unable to get the software to work with the programming cable.  Each time I selected the com port (4 in this case, oh, and even though this is a USB cable, it appears as a serial connection) the software would freeze up.  I suspect this is due to software updates that have broken the old driver.  It took a while but I was finally able to find the link to the USB cable site and download the latest driver.  With this new driver all was working fine again.

On to the software settings.  The following show the actual settings used to accomplish the mixing that I  mentioned above.
Mix 1 causing channel 6 to follow channel 1
Mix 2 adding channel 1 to switch B
Mix 3 adding channel 6 to switch B 
There are others who have rate settings for mix 2 and 3 set as low as 10 and as high as 75.  I thought I would use 50% so as  to give more room for experimenting.  In this case, 50% gives 50% down when applied and still leaves another 50% of down for ailerons.  Note also that mix 3 is -50% as this servo is reversed for aileron control.  Also note that with this particular transmitter, as the dials are associated with the switches, VR B will also affect the amount of flaps (adjust how much of the 50% is applied).  Just as a side note, my channel 5 is switch A, and I left that setup as a throttle cut off.  This is a whole other story as to how well that works with a stick programmable brushless speed controller.

In testing, all of this worked as planned!  Unbelievable that it worked on the first try.  This seems to never happen for me.  I am a happy camper.

Flapperon testing

So, now it's off to see how it flies!

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.