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Fantastic job. I love the propellers!
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Finished up the tissue trim on the wings yesterday and shot the fuselage/wings with a final coat of Krylon. After one more check of wing-stab-fin alignment I glued the fins on the stab. While that cured I jigged up the fuselage and wheel pants, cut the slots in the pants for the LG wires and glued the pants to the LG legs.
Once all that was solid I assembled the stab adjuster and rigged the stab to the fuselage. With the fuselage centerline level, the wing sits at +1 deg incidence. The stab can adjust from 0 deg to -2 deg - should give enough range to get a decent glide out of the model. Weight with the heavier of the two props is about 33.5g, and the balance is just about right on. The motor is pretty well centered around the CG so it shouldn't take much ballast (if any) to get things nailed. Last night I measured the plan PDF for wing area, stab area and tail arm, then calculated tail volume and target CG. The calculated number exactly matched the target CG Zaic identified in the article (.25" behind former #5, ~60% of average chord). Based on a 34g airframe weight it looks like the target motor should be about 12g, two 36" loops of 1/8" rubber. Less cross-section than I had expected, we'll see how it works. Next up is to rig the freewheelers and paint the props. Mike |
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I love the colors! The red and white over silver scheme plus the twin elliptical fins reminds me a lot of the old Super Constellation in the old TCA colors.
What's the weight on it at present? I'm sort of thinking that between all the structure plus taper of the wings that the model might just have enough wing loading to be at least promisingly resistant to thermals. As in a superb local field sport flyer that comes home with you at least semi reliably? For sport flying I'm rapidly becoming a believer in moderately reduced performance to aid with ensuring a long and enjoyable life span. |
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Thanks guys - I can't take any credit for the incidence meter, I just built it following Bill Schmidt's writeup (available here: https://www.stickandtissue.com/forum...num=1561867205). It's a really handy tool for small models.
Bruce, the TWA SuperConnies were my inspiration for the scheme, good to know the vision shows through. The airframe (with prop and peg, no motor) is just under 34g, giving an empty cube loading about 2.8. Balance is pretty close now, shouldn't need much ballast to nail the CG. Motor will be about ~12g, so flying weight will probably be ~46-48g, for a wing loading ~.55g/sq in and a flying cube loading ~3.8. While it's no featherweight, given that it'll hold a motor that'll take ~2000 turns I think it's going to be thermal bait. Been looking at how I might scab a viscous timer and swinging weight onto it without spoiling the look. Mike |
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Spent a leisurely couple of days rigging up the props. I used an in-spinner freewheeler dreamed up by Mike Mulholland from New Zealand (more info available here: https://www.stickandtissue.com/forum...m=1518394210/0.
It requires a little more work than bending over the wire on a ramp-style freewheeler, but I've found it very reliable on my Wicko and it keeps the front end looking clean. It'll also re-engage if the motor hangs up briefly and won't bind up if there's still tension on the rubber at the end of the motor run. There's a short video showing it in operation here:
I soldered the drive arm, but you can also assemble it with epoxy - just make sure you file a flat on the prop shaft and crimp the center tube of the drive arm to the flat before soldering or gluing it in place. That'll reduce the chances of the prop shaft migrating to the rear of the model if the joint fails. As you can see in the pictures I drilled a hole in the spinner for the hex key used to adjust the Gizmo Geezer nose button, and I added a 1/8" ring at the aft end of the spinner to reduce the gap between the spinner and the forward end of the fuselage. A little silver paint and some tip stripes and the props are ready to go. Mike |
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Last edited by MKellyvich; Oct 01, 2020 at 03:14 PM.
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Do you wind by hand?
Gene |
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It's all covered now so it'll be a bit of a "ship in a bottle" trick to bury something like a viscous button in the belly so it sits up in a little well between two stringers and two formers. But it should be doable. And trim on these is so touchy anyway that just a 1gm weight swinging away on a short line so it starts pulling at the nose or on one landing gear spat would be enough to make it go into a steeper spiral turn that isn't a spiral dive. That would get it down for sure.
It's too late now but even a flap that sticks out to the side like half of a clamshell speed brake would be enough to upset the applecart and bring it down. It doesn't take a whole lot to make one of these things try to turn into a lawn dart. Just consider all our efforts needed to avoid that in the first place ! ! ! Just one little bit of something, somewhere it shouldn't be and it'll be on the ground pronto. The trick is in making sure it's on the ground in only one piece ! ! ! |
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With the props done construction is finished! Put it on the CG machine - with the high-pitch prop the CG is spot-on with no ballast required. The motor is pretty well centered, any ballast necessary with the motor installed should be fairly minimal. 33.6g as pictured. Snapped some beauty shots this morning, hope to give it a toss this weekend (weather permitting).
Mike |
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