RC Pipistrel Panthera

Pipistrel Panthera - The Real Thing: Pipistrel Panthera - The Real Thing Step 1 is hoping mine ends up looking something like this.

RC Pipistrel Panthera Project - Introduction: This is a retrospective blog of my project to design and build an RC Pipistrel Panthera from scratch. Started October 2016. Finished January 2020. Lots of smaller models built along the way. When I first saw images of this plane back in 2016 I started looking to see if there were any RC models of it I could buy. None to be found. So I decided to scratch build one. I've been messing around with model aeroplanes most of my life but always small fry. That changed when I decided the Panthera would be 1:4 scale. Specs (cm): Full Scale 1:4 Scale Wingspan 1086.0 271.5 Overall Length 807.0 201.75 Overall height, gear up 185.6 46.4 Overall height, gear down 219.0 54.75

RC Pipistrel Panthera - Building the Plug: There were no plans available. So I relied on photos found online to at least get the outline shape right from a top, side and front perspective. Someone had done a 3D rendering in GrabCad, which was available online. This helped me figure out the cross section of the fuselage at different positions. With all this I went about creating a skeleton in hard green foam. I then filled in the skeleton with softer grey foam.  And started to hack away at it with a saw until the grey foam closely followed the contours of the green skeleton. Then came the sanding. This was difficult as there are no straight lines on this plane. If I over sand between 2 green skeleton pieces it will remove the curve. And a look from the side... Then coat it in primer and many layers of mould-release wax. Notice I built a plug but have not used it to build a mould. Instead I will lay-up the fibre-glass directly onto the plug. ...

RC Pipistrel Panthera -Fuselage: Laying-up the fibre-glass. Final layer used a white pigment to reduce paint layers required at the end to make it opaque. Once cured I cut it off into 3 pieces (main body, canopy, cowl) with a dremel. Then build out the structural internals. Still working on a bed as you can see. Very pro! Et voila! A workbench! And a fuselage complete with tail surfaces.

RC Pipistrel Panthera - Wings: Selected NACA-2412 airfoil. Positive incidence of 0.5° at root, gradually washing out to -0.5° at tip. I consider the incidence in this case to be the root chord angle relative the datum line of the plane. Essentially I want a very slight nose down attitude of the fuselage in the air at cruising speed as I think this just "looks right". The washout is built in to assist with landing. Narrow chord wing tips can stall easily so the washout should lower the tip-stall speed and make for more predictable landings...in theory :/ Checking it all fits 1/16" sheeting, top and bottom. My able assistant. Coming together Starting to look plane-like Foam wing tips...only way I could think of getting those nice curves. Impossible to know if both tips are the same shape but they look pretty close. Lightweight fibre-glass over the whole wing, top and bottom, and flaps and ailerons. Install servos (2 per flap, 1 per ai...

RC Pipistrel Panthera - Landing Gear: Electron retracts. Not cheap. But I couldn't find anything cheap that had the right scale.

RC Pipistrel Panthera - Painting: Layers of white primer and paint to overcome the shockingly poor finish I made of the fibre-glass. All in vain. The finish is still crap. But, assuming it flies, it'll still look great in the air. I'm telling myself that's all that matters. Very exciting. Painting the canopy finally makes the fuselage look less like a dolphin and more like a plane. Colour scheme applied to wings. Colour scheme applied to fuselage.

RC Pipistrel Panthera - A few shots below of the painted model. Only a few minor things to do before maiden flight. Finished with the following set-up: Motor : Turnigy Aerodrive Sk3 5055-430Kv. Prop : 16x6E APC. Will try 17x6 if I think I have ground clearance. Battery : 6S 6000mAh. ESC : HobbyKing YEP 80A. Not using the built in BEC to power the receiver. Receivers : FrSky X8R and X6R. U/C Retracts : Electron ER-30 main-legs and ER-40 nose-leg. RB-45 controller. U/C Retracts Battery: 3S 450mA. Servos (9 in total): Ailerons: 2 x Hitec HS-5245MG (25g servos). Flaps: 4 x Hitec HS-5245MG (25g servos). Elevator: 1 x Robbe FS MG wing servo (27g servo). Rudder: 1 x Hitec HS-5485HB (45g servo). Steering:  1 x Multiplex Mini HD - old analogue thing Receiver Battery: 2S 2200mAh Receiver Voltage Regulator: Jeti Max BEC