G-JIMG
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Everything posted by G-JIMG
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Made the under fuselage pod, and its aerodynamic fairing, using the same method I used making the engine cowls. Very pleased with result. Very sturdy but also very light. This is where I'd ideally like to install the batteries. As you can see, there's plenty of room for the batteries and I can install foam and straps to stop them moving around. The problem I have is attaching the complete 'battery pack' to the underside of the aircraft. Alternatively, I could manufacture a battery 'cradle' on the underside of the model and simply use the pod as a cover, attaching it by hooks and magnets as suggested by Chris. However, the pod spans the width of the wing and a small part of the fuselage so I will have to see if it's feasible to have the entire cradle on the underside of the wing. Jim.
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Nigel, I rechecked the broken flap and realised the hole for the hinge pin was at the wrong angle, it came too close to the top surface. Consequently, when I pushed the hinge back in, it burst through the thin wall. I've since made a new flap and everything is fine. Regarding Elevator operation: There is one metal rod bent at right angles either end. These are the ends that are glued into the Elevators. The rod has an 'actuator' arm soldered in the middle. The clevis for the Servo snake is attached to the end of this arm. There are two short lengths of brass tubing on the rod, one either side of the arm, these are glued to the tail. The brass tubes are aligned with the Elevator hinge pins so they have the same rotational axis. When the arm is moved up the rod rotates, moving the right angled parts of the rod downwards, which pushes the Elevators down. Likewise. if the arm is pulled downwards, the rod rotates within the tubes pushing the Elevator up. Jim.
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The mould came out very well. Jim.
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Chris, Personally, I use a thin layer of 3M putty to fill the weave and remove any surface irregularities. It dries fast and sands really easily. I only use Filler Primer if I want to add features, such as panel lines, to the surface. I place Chart Tape where I need the line, paint over it with Filler Prime, rub down until the tape is just visible again and then remove the tape. The resulting indentation produces a good effect when the final coat is sprayed on. Jim.
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This fibre glassing, filling, and sanding is never ending. Have to keep telling myself it's worth it in the end. Unfortunately I broke one of the flaps today . The hinge point is near the narrowest, and thinnest, part of the flap and the balsa gave out when I was reinserting the hinge. The flap on the other side is fine so I'm hoping it was just a weak spot in the balsa. Really annoying though, especially as it was pretty much ready for paint. Decided to do something other than work on the flying surfaces for a while so I've made a mould for the under fuselage pod. Next step will be to make a silicon mould so I can make a fibre glass part for the model. It will be the perfect size to take two LiPos side by side, an ideal battery pack. However, I still haven't settled on a method of securing it to the model. Ideally I want to be able to easily install and remove it without using screws (not very scale like) but I'm conscious that two LiPos are not the lightest of things. Any ideas would be more than welcome. Jim. Edited By G-JIMG on 22/04/2020 17:03:34
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Been working on the vertical tail assembly. It looks pretty horrible at the moment but will hopefully look good when it's sprayed with a top coat. The photo isn't very good so I've added some lines for clarification. As you can see, the Elevator Snake exits the tail outside the fuselage skin. I did this to keep the bend as shallow as possible and it isn't an issue because the King Air has a Dorsal Fin that will conveniently hide the snake. There is also a smaller diameter tube installed that will carry the lighting wires. Like the Elevators the Rudder also has a reinforced leading edge, but flush riveted. Again I've simulated this with metal tape. I have also simulated the 3 inspection panels with a thinner metal tape. The orange lines represent the Rudder torque tube. The snake from the rudder servo will run in a straight line to the bottom and, as the inner snake moves forward and aft, it moves the Rudder left and right. (the same servo arm will also connect to the nose wheel steering). Jim.
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Still fibre glassing, filling, sanding and basically prepping the flying surfaces for paint. The aircraft elevators have a reinforced leading edge. I have simulated this by affixing metal tape to the model's LE. I have also affixed acrylic 'dots' to simulate the rivet heads. Once spray painted the overall effect should be more realistic. The black line is 1/64" Chart Tape. I will eventually spray some primer over the tape, gently rub it down until the tape is just visible before removing it. The resultant indentation will simulate the Elevator Trim Tab once the model is finally spray painted. Jim.
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Still doing the tedious filling and sanding but took time out to make some cooling slots. The real aircraft has cooling slots either side of the nose and a scoop on the starboard side. I figured it would be easier to make panels that I can let in to the fuselage, rather than try and cut them into the skin itself. The panels are LitePly cut on the CNC machine. The starboard one has the scoop attached so I can let the entire assembly into the fuselage. The observant ones will have noticed the real aircraft has 6 slots whereas mine have 7. I tried it with 6 but it just didn't look right. Using a 1mm Bit and 6 slots leaves too much material between the slots. Using a 1.5mm Bit (my only other option) means you can only get 5 slots and not enough material between them. Anyway, as Platt's 4th law states, "How right it looks matters more than how right it is". Jim.
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Not much to report, the wing build has reached the tedious stage of filling and sanding before priming. In preparation for painting with primer I use 3M Putty on the surface: It's very easy to apply (the hotel key card again), dries extremely fast, is very easy to sand down and fills the fibre glass weave, and any surface irregularities, perfectly. It looks a lot worse than it is, the putty is not as thick as the picture makes it appear. After sanding with fine glass paper the surface is very smooth, flat and ready for paint. Jim.
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Posted by cymaz on 12/04/2020 12:52:10: Will you be putting a cap head screw and a captive bolt so you can access the linkage at any time? Edited By cymaz on 12/04/2020 12:52:26 Personally, I can't see why I would need to access the linkage in the future. I have used this sort of torque tube control on a number of models and never had an issue with it. have others had problems? If the linkage were to fail on the ground I would have to rebuild the tail. If it fails in the air I wouldn't have enough left to repair .
