Scale Swappable P51 - Design, Build, Fly

The Goal

The P51 Mustang has always been my favorite of the WWII warbirds. There have been some amazing swappable Mustang designs here on FliteTest (See related articles at the bottom) but one of the things that really makes a mustang is the iconic leading edge of the wing. I wanted to design a swappable that could be as scale as I could make it using the standard FliteTest build techniques of A/B folds, 50% cuts, and crush bends. 

Design Process

To start with I needed some good reference drawings to model from.

After collecting reference material and research I was ready to start designing in SketchUp. I recorded this design process as time lapse videos that go through the entire process from start to finish. You can view these at the end of this article. I've also posted many screenshots of the development in the build thread in the forums. That link is also at the bottm of this article. I took a lot of inspiration from both the FT Spitfire and the FT Racer with some major changes to get the wing geometry to fit with the Mustang's look. 

I pulled my three views into SketchUp and blocked in the basic shapes as simple outlines. By doing this I was able to lock in the scale proportions before I got to deep into the construction. Then I refined and worked out the various details of how the wing geometry would look, the standard fuselage and more specific details like the belly scoop and turtle decks. 

Once the design went through a few revisions I used the Flattery plugin to export out the parts in a .SVG vector file. If you're not familiar with what a 'vector file' is click here. From there I used InkScape to clean up and arrange the parts into a printable format. Using the standard print and tape up technique I cut out the shapes and traced them onto my dollar tree foam board.

Build Process

The wing has been the most complex part of the build. I had a first prototype that opened up some flaws in my design. I went back to the model in SketchUp and revised it and printed/cut a new set of parts. The second build was solid enough that it was worth putting electronics into. 

Maiden Flight

Once I started installing the electronics I realized I didn't have a Y harness for the aileron servos. After building one and fiddling with the servo extensions I was ready to put in the power pod and take it for a test flight. 

Summary

Since I'd been flying mostly FT Flyers and FT Nutballs this was much more plane than I was used to. I'm very much a newbie pilot. As this is my first scratch build design I've learned a lot over the process. I've really enjoyed taking something from idea and seeing it built and flying. Designing something from scratch is an ongoing process. I'm sure I'll be making tweaks as I build more of these. This is a warbird and from what I've heard, it flys like a warbird. The wing root plate is the only really hard part of the build and it may take some tweaking to get it in place. Also, Be careful to keep a good even dihedral angle when you build your wings. The portion of the wing that sits inside the fuselage should sit flat and the wings should have a clear symmetrical dihedral. 

Quick links for this article

• Read the entire build log in this forum thread
• Download the plans Page 1, Page 2, Page 3
• Learn to use SketchUp
• Watch the time lapse of the entire design process

Gear list

• Motor: D2822/14 Brushless Outrunner 1450kv (USA Warehouse)
• Battery: Turnigy 1000mAh 3S 20C Lipo Pack
• Prop: Slow Fly Electric Prop 9047SF (4 pc) (USA Warehouse)
• Servos: HXT900 9g / 1.6kg / .12sec Micro Servo (USA Warehouse)
• Control horns: DIY from giftcards
• Control rods: Music wire
• TX: Orange RX T-Six
• RX:OrangeRx R615 Spektrum/JR DSM2 Compatible 6Ch 2.4Ghz Receiver(International warehouse)
• ESC:Hobbyking SS Series 18-20A ESC (card programmable) (USA Warehouse)
• Canopy: 2 liter bottle cut and taped

UPDATE/SNEAK PEEK

I'm working on a 'body wrap' for this that could be applied with spray adhesive to up the scale look even more. Once this is complete I'll post a new article for it. In the mean time here's a sneak peek.