MiniacRC Swappable Mighty Mini P40 Curtiss Warhawk
~ Camouflage Skins and Other Mods ~
You may have chanced upon the release article of the MiniacRC Mighty Mini P40 Warhawk swappable a few weeks back. This model is an attempt to bring out the ferocity and maneuverability of the classic Flying Tigers from WW2, and provide another foamboard swappable to fly alongside the revered FliteTest mini warbirds.
The Mini P40 was originally intended as a gift for my flying buddy Dominic Peluso, who hand-painted his model with a heart-stopping camouflage scheme. However, since the Hawk flew pleasingly well and several beta builders had success with it, we decided to try something slightly different with the design.
It was beta builder David Haakinson who initially proposed the idea of creating paper skins for the P40. If you aren't familiar with the concept of paper skins for Flitetest swappables, view the guide article below featuring Stephen Rosema (Rasterize), who pioneered this technique and brought it to the mainstream of scratch-building.
The basic idea is to exploit the process of printing plans to provide 'premade' decals on your pieces as you cut and assemble them. For those who don't have access to painting utensils, this is a feasible option to decorate their scratch-builds by substituting skins for plans. There was only issue: I had never designed or even used a custom skin before.
I tried experimenting with the "spline" tool on AutoCAD® and it proved to provide enough flexibility for designing customized smooth curves while allowing for vectored parametrization. The result was a rather rudimentary template to create basic camouflage outlines and color fills.
I based the general scheme off of the Top Flite giant scale ARF P40. With the gradual addition of panel lines, rivets, exhaust stacks, wingtip insignia, Flying Tiger decals, serial numbers and shark teeth, the authentic look of the Warhawk was beginning to form.
The most challenging aspect of designing these skins was ensuring that the camo outlines from different pieces would match up perfectly when the plane was built. Fortunately, the mathematical precision available on AutoCAD® made it possible to design a continuous camouflage covering that built decently on the first try!
Printing and Cutting Process:
Download AIO Skins Here:
If you have scratchbuilt FliteTest airplanes, using paper skins is a simple step up. Typically, skins must cover at least the areas of the airplane that are exposed to the eye during flight. However, this leads to certain complications such as having to custom-locate the score lines inside the wing. Therefore, I compensated for my lack of talent in scratch-building by providing two sides of skins for every piece that needs to be cut out: a negative and positive side. The negative side is the one that we will cut with, and the positive side is the opposite covering.
As a result, you must remove paper from BOTH sides of the foamboard sheet before cutting, to avoid weight addition. (For a rough idea, each letter sized paper you add to your plane will add around 4.5 grams to the total weight.) The idea may sound tedious, but it actually renders the cutting and building process much easier and less prone to random errors. This was my first time using decorated skins and the entire build process – from printing the skins to holding up the completed airframe – took only a few hours over the course of two days.
You begin by printing either the tiled or the full sized skins, both of which are contained in the "AIO" skins document above. The full sized plans are scaled for ANSI D-size paper (34" x 22") and the tiled plans – for letter-size paper (8.5" x 11"). Make sure to print at 100% scale: for the tiled plans, this will render a 0.5 inch margin on all sides. Before cutting, let's go through the contents of the skins document.
Sheet A consists of the negative sides of most pieces on the P40. They are presented in full sized and tiled (A1-A8) formats. These pieces will be cut out exactly like standard plans, leaving bare foam on the other side.
Sheet B is the mirror image of Sheet A. You do NOT need to paste and cut these pieces out of foamboard: they are simply the opposite positive sides of the pieces from Sheet A. So they can be cut out with scissors and sprayed onto the bare foam mentioned above.
Sheet C contains both the positive and negative sides of just the right wing. Cut the negative side using tiles C1, C2 and C4 out of foamboard and cover the opposite bare foam using the positive side.
Note: Certain pieces such as those contained in tile A8 are simple to cut out and unexposed in the airframe so feel free to cut them out of scrap pieces of DTFB without removing the paper, etc....
The posterboard portions and some additional decals (insignia and shark teeth >:) are also included in the skins. Cutting the posterboard pieces should be doable with basic scissors, and the decals will be addressed in the instructions below.
Having printed out the skins, isolate any pieces that you think you can cut out of scrap pieces of foamboard that you have lying around. This may include pieces such as those in tile A8 that are not visible in the finished airframe.
Grab your scrap pieces of foam and as many new sheets of DTFB as you'll need. For those who have a hard time cutting through paper and foam at the same time, it may help to cut out all the negative sides with scissors so that the only cutting that needs to be done is through bare foam.
Peel the paper off of both sides of the DTFB. Pulling with an obtuse angle between your applied force and the path of the peeling will make the process easier and prevent tears. Also take note that the paper may peel easier along the grain rather than against it.
Glue the negative skins onto the bare foam using 3M Super 77 or any spray glue of your choice. You'll notice in the picture above that I only had to use half of a new sheet of DTFB for this build (for the wings). The rest are scrap pieces from previous builds. Cut out these pieces using your razor blade, X-Acto knife, or scissors. Do the same for the posterboard pieces including the canopy.
Now direct your attention to the positive side of the skins. You will need to cut these out using your scissors. The process may sounds tedious but the advantage is that when you spray-glue the positive skins onto the corresponding precut pieces from above, you will have created pre-decorated parts of your airframe!
When cutting out the positive skins, make sure to cut past the tile border lines as cleanly as possible so that the seams are not visible in the final product. That being said, even if some of the dashed lines show through, the P40 will still have its authentic look in the air and on display.
Note: The score cuts inside the wing are not extended all the way to the wingtips on the skins – for aesthetic purposes. Make sure to use a ruler and extend the score cuts physically till the wingtip to ensure a continuous fold-over. Once all your pieces are ready, the build process is the exact same as if you had used the regular plans. Please download the build guide from the release article for this design and you're all set.
Once you construct the wings and the fuselage, you are ready to add the shark teeth decals. Spray glue the teeth such that they line up with the front of the fuselage and bleed slightly forward of the scoop. The center-line of the teeth should follow the line where the fuselage and scoop meet.
Trim off the excess, and the menacing look of the Warhawk should be setting in. Adding a 1.5" plastic spinner should help establish the scale nose of the Mini P40.
Before you dive right in and commit to your build, here are some mods that you may find interesting as you construct your Mini Warhawk.
Aileron Servo Protection:
This is a mod suggested by renowned FT community designer Nic Lechner, also known as NerdNic. The landing gear housings are a key feature of the P40. While this design does not have retracts, the housings do in fact serve another key purpose.If placed in the scale location, the housings actually provide clearance for the aileron servo arms. A common issue with low wing warbirds is the stripping of aileron servos during hard belly landings. Due to the presence of the housings, your servos will be well protected even if you fail to land with your wings perfectly level. However, Nic mentioned that if you detest the look of servos underneath the wing, or would just like more anti-stripping insurance, you could glue on the housings over the servos themselves. Nic used this method on his Spitfire by hiding the flap servos with dummy radiators.
Fixed Landing Gear:
Adding landing gear is recommended if you are flying over smooth and hard surfaces like a model runway. The Mini P40 is an able belly lander and flares well on deadstick approaches. Its scoop is also structurally sound and can take quite a beating from nosedives and tree-ins (true stories). However, if you would like to add to the scale look of the Flying Tiger with taxiiing, takeoffs and tail-high landings, landing gear is a very easy modification to add. The method to add gear is identical to the one used on any FliteTest warbird.
Grab two identical wheels of diameter around 1.75 inches. Using 1 to 2 mm music wire, cut a 90˚ bend of length 1 inch at the end. Then measure 2 inches outward and bend the rest of the wire down from the plane formed by the first bend. Then measure 2.25 inches from the new bend and bend the rest of wire outward parallel to the first leg. This last bend will be the wheel shaft, so trim it according the thickness of your wheel. View the provided images to visualize the bends before forming them.
As Josh Bixler always mentions on his build videos, the idea with landing gear wires is to build one following the given dimensions, and then build the second one to match the first one as close as possible. Symmetry is the most important aspect in this process. Once you add your wheel to the shaft, lock it in using a collar or just add a dab of hot glue to the end of the shaft.
To mount these gear wires on the plane, trace out the shape of the connecting L-bend onto the bottom surface of the wing using a blade. Keep the gear as close to the leading of the wing as possible. The inboard end of your L-bend should be placed about half of an inch away from the sidewall of the belly. Add hot glue into the traced score cuts and press your wires in, scraping off all the excess glue.
This will result in a rather narrow but scale wheel-base that you can expand if you wish by bending the wires outward. The dihedral of the wing will provide some splay to the landing gear which well help during landings. However, make sure to angle the downward leg of the wire forward a little bit (10˚ to 15˚) so that the wheels are located forward of the plane's CG, preventing tip-overs during taxiing.
Using a tail-wheel may add unnecessary weight to your airframe, so try inserting a small piece of a bamboo skewer underneath the tail-end of the fuselage. Taxiing tests with this tail-skid proved that the plane had enormous yaw authority at very low speeds using just rudder control. However, if your Mini P40 doesn't track straight when you give it a push, make sure to adjust the wheel shafts to ensure smooth takeoffs.
Try to find a smooth even runway to takeoff and land your Mini P40 and if the gear every breaks off, you have two choices. Simply press it back in, or continue flying the plane as a belly lander. The Mini Warhawk will fly smoothly either way.
A huge THANK YOU to the beta builders:
This design would not have been possible without the wonderful team of beta builders from the FliteTest Fans facebook page. Their commitment, ingenuity and teamwork served to bring this design a long way forward of where it started. Here are two completed beta builds, both by gentlemen who have never used custom paper skins before to build foamboard airplanes. Make sure to check out the original release article to view previous beta builds.
By: Elias Bahbah
By: David Haakinson
My vision with this design is for hobbyists and young aspiring aviators to be able to experience the joy and thrill of building and flying their own little Warhawk with less than two sheets of foamboard and some posterboard. By all means fly this Mini P40 along with other mini warbirds including the FT Mini Mustang and Corsair, the NerdNic Sonic P39 and the MiniacRC Mini B25 Mitchell. Flying with friends is the essence of the FliteTest spirit!
I would like to thank Josh Bixler and the FliteTest crew for propagating this hobby in the grassroots in an educational and economical manner. Always remember: if you crash at first, fly and fly again! Thank you for taking the time to read this article and happy flying!!!
Signing Off – MiniacRC