Rc Scratch Build 20CC Just Aircraft Highlander

Hey Flite Testers, I'm working on a project and thought I would share my progress. A little over a year ago I was looking through YouTube and stumbled on a video of a Just Aircraft Highlander. I directly wanted to build that plane. So I searched the Internet for Plans and found a 54 inch version of this plane from Scott Swanson . I liked his plans but since I already had a lot of small planes I felt the need for something bigger. I decided to upscale his plans by 164,7% equivalent to a scale of 1/4,25. This would keep the length of the plane under 1,5m and it would still fit in the back of my car. It was my first giant scale airplane. I learned a lot by trial and error and I’m by no means an expert on this topic but I still hope you are interested in my project. I’m very happy with the way it’s come so far.  It was a fun process…  

The specs are:

• Wing Span: 225,9cm.
• Scale: 1/4,25
• Flying Weight: 4,95kg
• Motor: DLE 20CC Gas Engine
• Prop: Menz 17x8 
• Receiver Battery:  Zippy Flightmax 1100mah 6.6v LiFePo4
• Ignition Battery:  Zippy Flightmax 1100mah 6.6v LiFePo4
• Servos: 7x HobbyKing Ball Bearing Analog Servo 39g/4,5kg/0,13s
• Receiver: Spektrum Ar9020 with two Satellites

Wing construction:

Scotts plans call for balsa build up wing. In the past I had a bad experience cutting a bunch of ribs out of balsa and trying to align them all. So I decided to cut my wing out of styrofoam using a hot wire foam cutter. 

My hot wire foam cutter.

The templates for cutting the wings.

After cutting the wing out of a styrofoam block I epoxied 4mm plywood ribs to the root and the middle of the wing. They secure and keep the two wing tubes aligned.

For extra stability I reinforced the top and bottom of the wing with 20mm fiberglas band soaked in 24 hour epoxy resin.

In the next step the still wet band is covered with a strip of doubled up tape and is than...

...sandwiched between wing shells. 

While drying the wing is pressed betwenn two wodden board to keep it flat and straight.

Here you can see the two wing tubes I was mentioning earlier aswell as the now dryed fiberglas band. I cut a small hole in the wing to make space for the wing connector and for all the wiring.

Next the aileron and flap servo wires get installed.

With the wiring now in place the wing can be covered with 1mm balsa.

The finished wing root before covering.

The wing tip was constructed using 3mm balsa.

The wing before covering. In order to save weight I removed every second wing section. The wing is still strong enough and I saved 50g per wing. This might not seem like a lot for an airplane this size, but it adds up overtime.

Picture of the wing servo mount. I made in total four of them, two for the ailerons and two for the flaps.

The finished wing from the bottom.

The finished wing from the top.

Fuselage Construction:

The fuselage was build mostly according to Scotts enlarged plans. Nevertheless I used pine strips instead of balsa strips in many places to account for the greater weight.

The four main fuselage formers.

The formers are then connected with 5x10mm pine stock.

Then the rudder is added... 

 and with the firewall and the cockpit structure in place it starts to look like an airplane.

Working with pine instead of balsa wasn't always easy. To fill up small gaps in the joints I used pape soake in thin CA. Later i drilled a small hole through all structual joints and glued in a toothpick for added strength.

The last important step is to glue on the fuselage side covering made from 1mm aircraft plywood.

Starting the engine for the first time was really tough. I had absolutly no experience with gas engines and nobody around me who could help me. But once the carburator was wet it started fine with just a few flips of the propeller. I used a digital tachometer to check the RPM of the engine which made adjusting the carburator a peace of cake. Once I was satisfied with the engine performance ... 

...I installed it into the airplane. By now only three things were left. I had to laminate a custom cowling, I had to construct and build a landing gear and I had to cover the whole fuselarge.

Unfortunately I have no pictures of the cowling lamination. But I want to tell you one thing. A shiny cowling need a lot of sanding and filling and by a lot i mean around 10 hours!

Landing gear Construction:

The landing gear was build using 4mm spring stell and 5mm rass tubing. 

The two landing gear legs after painting.

All the pieces of the landing gear hung up for painting.

 The finished landing gear.

After covering the fuselage looked amazing. After over 12 months of work she was almost ready for flying. I still had to cover the right wing but that didn't stop me from assembling the whole plane to finally get a feel for the size. Because so far I only had  a few plans and a big vision in my mind. The first time I assembled the complete plane. It's huge! It just barely fits into my basement. 

The finished plane:

Maiden flight:

It was the first time for me to fly a large scale gas plane so I was excited to get it in the air. Last check before takeoff...

...and with half throttle...

...the Highlander took off and was in the air in no time!

Flying this large scale plane and hearing the sound of the gas engine were both a really fun experience!