Swappable P38 w/Plans - Twin engine goodness

So I just got into this hobby about a month ago and my wife has accurately labeled me as obsessed. I have built 5 FT planes and can't wait to build more. That leads me to the reason for this article. My father and I both built a spitfire from a speed-build kit and it was an amazing experience. The planes fly great and look amazing. If you haven't built a Spitfire, you should. 

The problem is that I am not easily satisfied and I started thinking about designing and making my own plane. I try to avoid things that contain the words "beginner" or "starter" so I usually jump in with both feet into something more advanced. I started by making a basic model in Sketchup that sort of looked like a P38, but it wasn't pretty, so I did some research and found some better techniques. To get the dimensions I took a 3 view of the actual plane and traced everything as scale as is possible with foam board. I believe that the dimensions should be fairly scale with the Spitfire so you could fly them together and it would look accurate. I did my best to make it using the build techniques and concepts used by FT on the other builds so if you are familiar with building their other planes you should be able to make this without too much of a learning curve. It is designed for 2 power pods, but it would not take a whole lot to install a permanent motor mount. So here it goes.

Specs

Wingspan: 54 1/2”

Dihedral: 5 Degrees

Length: 36”

Motors: 2x 1100kv 2208-17 Outrunners

Speed Controller: 2x 20A

Battery: 1x 2200MaH 3S 25c LiPO

Servos: 3x 9 gram

Props: 9x4.3 (I would recommend using a steeper pitch blade but these were the only pair I had available)

Aileron, Elevator, Differential thrust in place of mechanical rudder. 

My maiden flight went really well. The landing...not so much. I discovered that although it flies slow rather well, it does not glide all that well. After a rather impressive cartwheel following a stall I found that this plane can take a hit and keep on going. The wing tips got a little bent up, but nothing that a little packing tape wouldn't fix. I picked it up and chucked it back in the air and it flew just as well with mushed wingtips. If I keep up the power until just before I land, it goes much better. Make sure you are comfortable with 4 channel planes and using the rudder before lobbing this monster skyward. I wanted to keep the design as simple as possible so I didn't design it with a mechanical rudder. I decided instead to use differential thrust by mixing in 2 throttle channels with the rudder channel.  

I have included scale PDF plans so if you want to make some modifications you can do it without too much difficulty. If anyone knows how I can post the Sketchup files that would be great. When I try to upload them it just says "Bad Data". My guess is that file type is blocked. I also uploaded the 3D model and the 2D plans to the Sketchup Warehouse. http://sketchup.google.com/3dwarehouse/details?mid=f548f4e302169b4445f31985fc702c6e

To make the 2D plans I copied the surface from the 3D model and pasted them into a new drawing and flattened them out. That way I can make modifications without having to re-do a whole lot. The 3D model is to scale so you can take measurements and dimensions off of it if need be. It took 5 sheets of foam board, but that is because it is gihugimous. I haven't had a chance to mock up the removable nose/battery holder. I just got creative with some scraps of foam and poster board. I will post more pictures when I get a chance. I just updated the plans to include the plate that holds the skewers for the power pod

You will also need a hand full of servo wire extensions. The elevator servo needs to be about 50” long (I used a 36” and an 18”), and 4 more 18” extensions for the speed controllers and ailerons. You'll need a Y-Splitter for the aileron servos. I just stole the one I had for the Spitfire. I wanted to keep the weight down so I made an 18” Y-splitter for the power and the speed controllers share a battery, but I made the cockpit large enough to carry 2 batteries if you so desire.  

I tried and tried to come up with a way to make the wings removable, but since they are both attached to the elevator it's pretty much impossible without weakening the structure or making it too complicated. Feel free to play with the designs and let me know if you have any workable ideas. Here are some pictures of the final product. I will try to get some video of it in action in the next couple of days. 

 The video is a little jerky but I think it's pretty good considering it was taken by my 5 year old son on my cell phone. I love the theme music on the first flight. 

 Tell me what you think and if you decide to build one. More pictures coming soon. 

Thanks for reading.

P38_LeftWing_Plans.pdf

P38_RightWing_Plans.pdf

P38 Elevator/Rudder Plans

P38_Cockpit_Plans.pdf

P38_LeftNacelle_Plans.pdf

P38_RightNacelle_Plans.pdf