Nigel R
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Everything posted by Nigel R
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What's more classic aerobat than a mechanical trike retract setup using retro retracts? So I decided to make life difficult for myself and use some retracts. Here are the two mains installed right behind the main spar. They are Goldberg units. Quite light. All nylon units, very simple design, only three nylon parts and a wire leg. Now, do I go full retro and run all three units from the one servo? Edited By Nigel R on 20/02/2017 09:04:24
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The difficulty definitely needs increasing to 100%. Sometimes you need to play with control throw settings and some other stuff, too. Phoenix is generally great although it has a couple of real issues, model behaviour when the wind is turned on, in particular, is very strange.
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Last one for today! I cut some doublers for U/C mounting. 1/16" birch ply, 1/8" hard balsa spacer (all will become clear in the next set of pictures hopefully).
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Next up, servos to install. I didn't get any photos while I was doing it but its easy enough to see what I did, nothing unusual again. Here's the top side of the wing with the hatch in place: and the underside: And from the side, showing what the hatch mounts on: And, the hatch itself with a servo attached: And a final shot with everything in place: Phew! The hatches are 1/8" liteply. Liteply can bend a bit, which means it can be made to match the wing surface quite well. To this end, there are two liteply doublers stuck to the ribs, which have a curve that follows the airfoil. The doublers are (if I got it right) mounted at the right position to make the hatch line up with the wing sheeting. The hatch screws into four mounts; these are liteply squares with some small block balsa reinforcement. The servo screws onto a liteply strip, which is glue direct to the hatch. A hard triangle of balsa provides support. The hatch has a 5mm slot cut into it for the pushrod. Finally, there's a bit of 1/8 balsa to box in the servo area in the wing itself. For the most part, I'm not a liteply fan. I prefer birch ply. But the 1/8 liteply is rather good at taking servo screws - balsa isn't quite enough and birch ply or some other hardwood seems a bit overkill here.
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Here's two panels, after the sheeting operation is done: And several hours later, after adding the TE sheeting and cleaning up the root and tip:
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Some updates; I put together the right panel. Looked just like the left but the other way around. In the middle, we need a couple of scrap block reinforcements for the wing dowel. Some leftover 1/4 and 1/8 provided these: You can also (just about) see the D box sheeting in progress here (see yellow contact adhesive, and small hole in spar). I always used contact adhesive for sheeting, its quick and easy. Got that one from my dad years ago. The hole (for a locating peg) is a recent addition to the technique. It goes like this: Get wing panel jigged up and held securely in place. Place sheeting over wing. Drill a 2mm hole throught the sheeting into the spar at the root and tip. Poke a cocktail stick through the holes. This gives 2 solid locating pegs so that the sheeting goes back in exactly the right place. Run a bead of contact adhesive over the structure. Press sheet down in place, make sure you get good transfer of glue from structure to sheet. Remove sheet, drink coffee while glue dries. Eat biscuit. Use pegs (which are still in the sheet) to positively locate the sheet. Press down gently to get good joint over all parts of structure. I find this works best when you use a sub LE of 1/8". Then the real LE goes on after the sheeting has been sanded back to a nice flat surface. This gets a really good secure joint at the front. Rather than relying on a 45deg strip and edge joining the sheeting to it. Here's the sheeting, with glue in all the right places and a peg poking through:
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Fairly sure my dad is building one, although he's not on the internet, so I'm afraid there won't be any news of the build posted here! I'll try to get some details from him when its done.
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Toolstation have this 30 min PU for £10 or thereabouts. Anyone used it? (There is a toolstation close to my office). Lumberjack is currently listed on EBay for £8.50 posted - here The tool-net site linked above shows £7 for postage! Edited By Nigel R on 13/02/2017 08:45:40
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I like this design. Similar feel to the Cranfield and Akromaster. That short nose should suit the four stroke unit nicely too. Posted by Denis Watkins on 31/01/2017 18:31:12: Consider beefing up everything Tony, as the design is for something like 700W and your fitting will be around 1100W I'm not sure you'd see 1100W from a 70 size 4 stroke. Just over 1hp (800W?) by the time you're running regular 5 or 10% and it is propped down to 9000 rpm. I've seen specs claiming the Saito 82 is 1100W output, but under what conditions, high revs and a barrel of nitro? Some sources can be very optimistic... Edited By Nigel R on 13/02/2017 08:28:55
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Made a start on the left panel. All completely conventional structure.
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"I then tried the tank from the model with the engine still in the test stand & again no issues. I was then going to try the tank with the extra clunk line on the filler pipe refitted " can't help but think you must be getting close here. the setup in the test stand is differing because: actual fuel lines are different? tank height different? silencer pressure not fitted? possible (and not visible) vibration issues? [maybe affecting o rings or needles]
