Corsair Swappable with Plans

So here it is! My version of the Corsair in full delicious swappable fashion. I have been toying with the idea of building one of these for a while but I wasn't sure how I would make the wings straight and rigid until I saw the build video for the Simple Soarer. When I saw how Josh made the polyhedral for those wings I had an AHAH! moment and I went to work. Just like with my other 2 models (articles linked below) I started with Sketchup and modeled everything over a 3 view of an actual Corsair. This makes it so much easier to get the dimensions right. I took a video of the maiden flight and for some reason my camera doesn't appreciate the finer intricacies of filming small moving airborne objects so a lot of the video is out of focus so I apologize in advance. It's not a spectacular video but it's good enough to demonstrate that it does indeed fly. I have a Mobius cam on the way for Christmas (YAY!) so hopefully my future videos will be of a higher quality. I had a chance to fly it again when it wasn't as windy and it flew beautifully. It doesn't tip stall like I have heard is common with the Corsair design. I attribute it to the large undercamber on the wing tips. It keeps it stable while still allowing it to be maneuverable.

Specs:

Wingspan: 37"

Center of Gravity: 2 5/8" back from leading edge of wing

Motor: Emax GT2215-09 1180kv ("the beef" from Lazertoyz.com)

Prop: 8x6

Battery: 3S 2200mah

ESC: 20A

This is not a beginner build, but it is rewarding because it just looks so stinkin cool when it's done. I will do my best to share what I learned while building this one. Everything I did is based off of the techniques and build style of the other FT planes, so if you find yourself wondering how I did something, start by watching the Spitfire, Simple Soarer, and Baby Blender videos. Most of what you will need to know is in those videos and FT does a much more entertaining job of explaining and demonstrating it. Grab some foam and let's get started!

It pretty much goes without saying, but it all starts by printing off the plans and cutting out the pieces. Since the wing dihedral is not at a right angle with the fuselage it is SUPER important that everything on the fuselage is square and true. If it is crooked it will throw off your wing alignment and a crooked wing makes for a short flight. I use a square to make sure everything stays lined up while the glue cools. Be patient with this and give it plenty of time. The fuselage uses what Josh calls a B style fold so the sides of the fuselage go beside the top and bottom plates. It shouldn't be too hard to figure it out since the plate in the middle that holds the power pod won't fit correctly if you use the wrong fold. I started out by glueing the power pod plate on 1 side. The other side of the plate will be glued in the second to last step.

After the plate is glued on, go ahead and glue the rest of the sides one at a time starting with the side you glued the plate to. Don't try to glue the top plate at the same time as the side plate. The glue will cool too fast and you'll end up with a crooked fuselage. You will also want to make sure you don't glue on any of the formers until the wings are installed because you will need to lay the fuselage down on a flat surface to line up the wings when you glue them on later.

 Once everything is squared up and you're happy with it you can start with the wings. I tried to get the plans as close as possible but inevitably you will most likely have to do some trimming to get the dihedral correct. This wing is made using almost the same technique as the wing on the FT Simple Soarer. If you want to see how it's done I have linked the build video below in the related articles. Just for reference though, the bottom of the wing is solid so don't cut all the way through. I did this to make sure the wing stayed straight and rigid and I'm happy with the results.

Since every wing is different I did not put the angle for the spar in the plans. I just folded the wing over and once everything looked right I marked and cut the spar anywhere it stuck out into the hinge area.

I didn't get a picture of it but to get the proper dihedral you just push the shorter section of the wing flat against a table and put an 8 7/16" spacer under the wing tip and glue away. Make sure the wing isn't pushing hard against the spacer or you won't get the proper alignment. After the glue cools you should be able to place the spacer under the wing tip without much resistance.

Once the wings have been assembled, place them beside each other on a flat surface to make sure they match. The wings should mirror each other as closely possible.

The way I installed the wings is a tad different but it's the simplest way I could devise to ensure alignment. I put a couple of small pieces of tape on the edge where the 2 wings meet and did a dry run to check the fit. I had to trim a small amount from each wing to make them fit. I just made two 1 1/2 inch square spacers for the wing tips. When everything fits correctly the wing tips should rest just above the spacer blocks and require slight pressure to touch the spacers. One step I missed that caused a headache later was to install the servos before gluing the wings on. Thankfully my son's hands were small enough to reach in and feed the wires through. Otherwise I would have had a wall hanger.

When you are confident that everything is ready, go ahead and glue on the wings. The front of the wings should be 4 7/16" back from the front of the fuselage, or just behind the second set of formers. I started with the bottom plate and then I glued the top surface of the wing to the fuselage. The main reason is that I have the worst luck when it comes to hot glue becoming cold glue, so I like to keep the glue areas as small as possible. This also allows more time to verify that everything is aligned before moving on. Make sure you press the fuselage down hard against a flat surface and put a fair amount of pressure on the wings. This is a crucial step because if you don't get the wings right here you'll have to start over from scratch. If everything goes according to plan you should be able to set it down and have the wing tips touching the spacers without rocking or lifting up the fuselage.

Another thing to check is to make sure that when you set the plane right side up on a flat surface it doesn't rock back and forth. If it does you probably have an alignment issue. Don't worry if you do though. I had a little warp in mine but I was able to get it squared away by leaving some carefully placed books on edge over the hinge line of the wing overnight.

These next pictures show the placement of the formers. 

The final piece on the front of the fuselage is purely decorative but I think it adds a nice touch. After everything was assembled and the poster board was on, I cut a bevel in the front and sanded it down to give it a nice rounded edge. I wanted to keep it simple but still make it look nice and I think I've accomplished that.

Now to install the poster board. Be patient and take your time. The shape I put in the plans should get you close, but since your model will be different, you will need to do some trimming. I put the poster board on the front first and then the rear. It gave it a cleaner look. I also made the bottom section a little long so you can fold it over and trim off the excess.

I also put a beveled piece of foam board in front of the wings on the bottom to even things out for the battery. It also finished off the bottom nicely and covered the edges of the poster board. I also put a small strip of packing tape over it so I could put on velcro for the battery. I put in a strap to secure the battery. It's no fun when it becomes an actual drop tank.

I waited to install the tail servos until the end. I realize that you won't be able to push them flush against the fuselage, but you can glue the back of the servos and they should stay put. Just make sure you don't press them in too far or you'll dent the poster board and it will look a little screwy. If you feel enterprising you could put the servos in the cockpit and run the control rods through the formers, but I didn't have enough wire and didn't feel like running them through. It would look cleaner, but I was running out of time so I took the easier route. 

There you have it. I plan to paint it but that is just an esthetic piece that you can have fun with on your own. I will post pictures of any improvements or additions I make.

This plane has great lines and a distinctive look that I really like. Some people hate the Corsair but I like it because it's unique and challenging to build. I hope you enjoyed the article. Please let me know if you build one and share your experiences with me. I really would like to know if you use these plans. Have fun and fly often!

Corsair Complete Plans.pdf

Corsair Fuselage Plans.pdf

Corsair Left Wing Plans.pdf

Corsair Right Wing Plans.pdf

Corsair Formers Wing Plans.pdf

Corsair Front Poster Board.pdf

Corsair Rear Poster Board.pdf

Corsair Canopy.pdf

Flynn was kind enough to start a build thread on the forum. Feel free to post comments and questions. 

http://forum.flitetest.com/showthread.php?6687-Swappable-Corsair-by-Filken

UPDATE: It was brought to my attention that the plate that holds the power pod was not on the original plans. I have posted updated fuselage plans with the plate. Everything should be correct now. 

I have also run out of puppies so better luck next time!