RC FrankenPlane-CBRC

Frankenplane-CBRC

Hello everyone, my name is Colin, and I recently built this RC Frankenplane. It is based on the same idea of the Flitetest frankenplane back in 2011. This article will be overviewing the build and maiden flight. This is my first Youtube video and FT article, so any feedback is welcome.

All of the parts of the frankenplane (including electronics) are from three different airplanes that I crashed in the past. Those planes were the Hobbyzone Firebird Stratos, Hobbyzone Firebird Delta Ray, and Hobbyking AutoG-2.

The Overview

The Build

Wings

To start the build, I took the wingtips and elevons/ailerons off of the Delta Ray and attached them to the wing of the Firebird Stratos.

After that, I covered the previous twin motor holes in the wing of the Stratos with clear tape to decrease drag.

Then, I took the wing apart to find a plastic spar in the center. The wing was very flexible with just this, so I added Carbon Fiber both to the center of the wing and to the wingtips (which I under cambered).

After gluing the wing back together, 3 magnets were added, in the hope that they would sufficiently hold on the wing alone.

To finish the wing, I installed a servo to control both of the ailerons. Unfortunately, there is a lot of slop, but it still works OK.

After setting aside the wing, I began work on the nose.

Nose

After I crashed the Delta Ray about 1 year ago, it was in 2 main parts; the wing and the nose. For this part, I took the nose and made it so it was flat on both the front and back. I also cut a hole for my DT750 motor to go into.

This shows the thrust angle in the motor

Also, there is a tunnel going through the Delta Ray’s nose, which is good for putting the leads of the ESC/motor.

The next step in the build was to build the fuselage and mount the wing.

Fuselage

As said in the beginning, I used my destroyed Auto G-2 for the fuselage.

I began the work on it by cutting off the original blade mounts and flattening out the top of the fuselage to properly mount the wing. The 10mm carbon fiber boom was left on.

After that, the magnets were installed on the fuselage to line up with the ones on the wing.

I then added the electronics to the fuselage. Here that is completed.

To finish the fuselage, I added the nose with the motor in it onto the front of the fuselage.

Tail

The tail was probably the quickest part. I use the existing horizontal stabilizer and the tail mount of the HK Auto G-2 boom, along with  the cut-down and reinforced HZ Delta Ray vertical.

To control the tail wheel, I used the existing set screw system that uses the same servo for both the rudder and the tail wheel.

After the maiden, I cut down and beveled the vertical to increase aerodynamics and decrease weight and rudder authority.

The Tests 

Taxi Testing

Usually for a prototype, I glide test to find the proper CG. But with a model this size (even though it's not that big), I decided to taxi test it instead. It gave me a pretty good idea about where the CG should be.

The Maiden

Finally, it was time to maiden it. At this point, it had a relatively low AUW, but I anticipated it not flying at all. Upon taking off, I realized that there was not enough thrust angle on the horizontal axis. So it veered very closely to a nearby fence on the side of the runway. I pulled up quickly and took right also which was there’s surprising, but the plane was a little tail heavy.

I then started doing loops and rolls but found quickly that the rudder had about 5x the authority of the ailerons. Rudder alone would make it do a wing-bending spiral, which I recovered about 3 feet above the ground.

After that, I tested the stall characteristics. The combination of full wing vortex generators and under cambered wingtips makes this plane stall beautifully.

Then, I attempted a low pass, which turned into a touch and go. Unfortunately, I never got to the “go” part, as the plane ran into the fence. There was very little damage; the only problem was that the motor fell off.

All in all, the Frankenplane project was by far my favorite project to date. It turned out to be wonderful because the parts were all compatible, and worked very well together. Also, the build was not very time-consuming, which took away a lot of the frustrations. Not only that, but I have found that I really like builds that are similar to this more than starting from scratch.

On the other hand, the build did have some downfalls. For example, The battery mounts in a very inconvenient place that causes a lot of drag. Also, the magnets turned out to be a let-down, because they were not enough to hold the wing on alone, as said earlier. Even with that said, the positives out wieghed the negative by a ton (by .55lbs to be exact;).

If I was to do this build again, then I would find a better way to mount the motor on the plane, so that it was stronger and lighter. Also, I would have built the fuselage different so that the battery would be mounted within it.

You can support me and my builds by subscribing to my YouTube or commenting on this article about how I can improve in the future. Thanks for reading!