3D F-16 FOAM SCRATCH BUILD
Hi everyone, this is a copy of a forum thread I posted some time ago. I thought that some may like to see it as an article. I started two Scratch Builds a few months ago, the F16 and a Flying Wing. Well the first one is finally finished....yes a few months ago! (Only because I had to wait for parts!) The actual build itself would only take a day or two, so don't get concerned about the time lapse.
Anyway somewhere along the line someone told me that the Australian Air Force never flew F16's and to the best of my searching I couldn't find anything to the contrary. So I thought I would take it upon myself to make a few minor changes to history... "In my own way!"
CHOOSING THE PLANS:
The first step was easy, choosing the plane to build. While wondering around the many pages of plane designs on the net I came across the webpage of: “frcfoamies Boxermad84.”
As this was my first attempt at building a plane out of foam the F16 on this page was really appealing. (I have to say that if you haven't already visited this site I strongly suggest you have a look at it, whether you are interested in 3D or full form body foamies).
So after printing the design I thought the easiest way to join the pages together was by sticking them on a window with the light coming from behind and over lapping the pages to ensure I matched the lines up correctly. Cut the shapes out and position them on a 1000mm x 700mm sheet of Depron. I just held them in place while I traced them out with a pencil. I know some people choose to stick the templates to the foam but I had no problems at all just holding them and didn't have to separate the paper and foam later.
Here in West Australia Depron is very expensive. The best price I can find is $15.00 for a 1000 x 700 sheet. This was from a company called Trade Warehouse Direct, up at Wangara. As a result of this outlay every step is checked, double checked and so on....
I decided that since I had a long wait ahead for the arrival of parts, I would start painting the plane while it was still in pieces, the only joint in place at this point was the two main wings, minus the carbon spar. I used Tamiya model paints to colour the foam. I used a airbrush to do the painting but for anyone that doesn't have a compressor and brush set I would suggest maybe water based spray paint cans. Now that the project is finished I have to say that although this spray technique is very effective and very enjoyable, it is a very expensive way to go. Since this project I have been experimenting with all kinds of different foam safe paints and am hopefully closing in on one.
Eventually all the parts I was waiting for arrived so it was time to finish the build, so there are the steps I took:
1. Cut out a thin channel across the bottom of the main wings and glue a 2mm carbon fibre rod in place, then tape across the entire length with extreme tape.
2. Glue the two walls of the underside to the bottom of the main wings to create the basic under belly.
3. Glue the lower tail piece and centre wall of the undercarriage in place.
4. Glue the nose and tail wing into place which then finishes the overall shape of the plane.
(This is one of the original photos of the pieces just placed together, no glue just a bit of sellotape)
5. Cut a line into the base plate from side to side, approx' half way along the plate and use extreme tape to create a hinge in the same fashion as creating ailerons or elevators. Once you glue the base plate in place the hatch will then form the access door to all the electronics. Use a wooden skewer to pierce the sides and the centre walls under the base plate, pushing the skewer into place. Use a single strong, or a number of normal rubber bands to lock the hatch in place protecting the electronics.
6. Using a piece of plywood found in a local industrial bin, I drew and cut out a @2” circle and shaped and cut as needed to make a motor mount. A template for the mount is in the plans.
7. You will find 2 small wedges of foam in similar shape to a house??? with a long channel from top to bottom. These two items are then glued in place behind the mount to help secure it.
Be sure to try the motor mount to ensure it fit before glueing.
Also be sure to screw the motor onto the mount BEFORE you glue the mount in place.
I also used a large drill bit to drill out the centre of the mount, which I think will help with air flow to the back of the motor. I know this is not a main issue (may not even make any difference) but I thought it was worth while anyway!
8. The last part of foam work is the elevons. You will see that I put them on early in the piece but I would strongly recommend you leave them as late in the build as possible. They seemed to always be in the way while I was working on this plane. Once again a steel rule and a sharp knife was used to angle the joining edges to the plane. NOTE: Make the cuts on the bottom surface to save seeing them from the top.
9. Once they are secure and working as you want, you can glue the horns in place. NOTE: Before you do glue the horns place your servos in position you want and use a straight edge to work out where you want to glue the horns on. The idea is to ensure the push rods are able to work in a straight line. It will look much better if the rods are nice and straight and even!
10. Servos! I will leave the selection to you as everyone seems to have their own favourites, but I will list what I used at the end of the article.
TIP: One little idea I use is to cover the servo with maskingtape before glueing them to the plane, be as particular or sloppy as you like, but you will be grateful you did cover them if you crash the plane and want to re-cover the servos to use again. The tape prevents the glue contacting the servo body thus making it easy and clean to recycle them.
I also used horn connectors on this build but that's up to you, I just thought I would spoil myself!?
As I have mentioned a number of times this was my first scratch build and my first attempt at the electronics side of things as well.
In with my parts that arrived this week was also one of the Turnigy 9x transmitters. So I had to get my head around that at the same time as working on everything else, so it's just as well as I have a lot of time on my hands! Some of the instructions sounded more like I was to perform brain surgery than control a plane!
I decided that for my first build I would go with the same kind of spec's as Boxermad84 listed on his page with only 1 or 2 minor additions/alterations. After soldering a couple of plugs I set things out in order to TRY and keep some control of the CG. I managed to get the final CG equal to the motor mount, which I think is probably as close to where it should be as possible. I was really pleased with this result.
In order to keep the servos right down the back with very short push rods, I had to use extension cables to reach the receiver. Obviously this was going to cause grief with cables hitting the prop. So to alleviate the problem I visited the local deli and pinched a simple drinking straw. I cut it in half and then ran the knife along the sides to open the two pieces. I ran a bead of glue along the walls of the plane, beside the prop and placed the straws in the grooves before feeding the cables into them and sealing them with another dab of glue. Thus keeping the cables tight against the wall but not glugged up with glue.
Once I moved everything into position I was able to secure the CG right in line with the motor mount.
So there you go, finally the build is finished and now ready for the test flight. Oh and for good measure I added a couple of skid plates to the bottom....Just in case I found some concrete to argue with during a landing somewhere!
The Flying Cobras...!
List of Items Used:
1. 1 Sheet of 1000x700 Depron Foam
2. 1 x small piece of 3ply Plywood
3. 1 x RC Timer BC-2212/6 2200Kv Brushless Outrunner
4. 1 x 6x4 Plastic Prop
5. 1 x Mystery 30Amp ESC
6. 1 x Receiver (3channel) (For the time being I am using the Turnigy 8ch receiver that came with my transmitter.)
7. 1 x 1300mAH 11.1V 3S Battery
8. 2 x 9gm Metal Gear Servos
9. 1 x length of Push Rod – cut as required
10. 2 x Extension Cables
11. Extreme Tape (Clear)
12. 1 x 2mm Carbon Fibre Rod
13. 1 x Long Wooden Skewer
14. 1 x Heavy Duty Rubber Band
15. 2 x Skid Plates
16. 2 x Control Horns
17. 1 x Set of Bullet Connectors 3mm
18. 1 x Set Deans Connectors
19. 2 x Small Piece of Red & Black Shrink Tube
20. Blue Wing Tape 45mic x 45mm
21. Yell Wing Tape 45mic x 45mm
22. Decals of Choice
23. Paint of Choice
I hope you enjoyed this Build Log.