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Old Jul 30, 2012, 09:26 AM
gordonnora is offline
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Ross,

Mine is moving along nicely...I've got the fuse together, and will get the bottom piece on tonight...It's so small its hard to lock it down to the bench, but it has come out nicely, almost self jigging...The nose block should go on shortly...I need to order Mark's tow hook...

Did you adjust the incidence on the stab? Mark mentioned 1 degree, but I wasn't clear on which line to use at the reference....

I have a five year old and a soon to be three year old, so its hard to find time dedicated to strictly building....

I did punch out the wing ribs this morning, so the wing will be following soon....

What size battery did you use? Which receiver did you use?..I can't find the micro stamp that Jack used in his..Has your flown lately?

Gordon
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Old Jul 30, 2012, 05:40 PM
Mark Miller is offline
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Gordon,

I reised the trailing edge of the stab by about 1/32 which should give another half degree of decalage. I think that should work out well. I decided to move the stab as lowering the trailing edge of the wing required many more changes.

I have ordered the first run of production parts so I should have some kits soon.

Mark
Old Jul 30, 2012, 05:43 PM
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BTW...On mine I used a Hyperion 850 mah LiFe pack and two Airtronics 94814 servos. I used those servos to cut the holes in the servo tray. These are about the same size as Hitec HS-85. The Hyperion DS-13 should work great too.

Mark
Old Aug 04, 2012, 12:12 PM
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Well of course things could not go easily. I sent in the order for laser parts and the laser my laser guy uses is broken. He is working with eht mfg. to find the issue and get it repaired. It is a big 100 watt unit which makes better quality stuff especially on thick balsa and ply. No ETA on when it will be fixed. Be patient guys. It will be there.

Mark
Old Aug 04, 2012, 01:36 PM
Pauliwog is offline
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Washout or Not??


Hi, I skimmed around and maybe I missed it, but just curious if anyone has put washout into the wingtips of their Duets or not?

And if "Not", then I'm curious about "Why not?" what is it about the tips or overall design that allows for not needing/wanting washout, is the airfoil at the tips different than at the root or midwing? Or do some constant-through-the-wing airfoils just do nicely and not need it, and what feature of the airfoil(phillips entry? thinner vs thicker? highpoint before, right on, or behind the top spar? etc) avoids stalling in tips? the top/bottom view outline shape of the tips? Sheeting vs turbulators from leading edge to top spar?

Thanks - Paul
Old Aug 04, 2012, 02:21 PM
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With careful airfoil choices washout isn't strictly needed on all designs. Drela's design for the Supra uses different airfoils across the span and effectively increases thickness at the tips. That increase in thickness delays localized stall which allows the root to stall first. Sure you can stall the entire wing but if you enter slowly, say in a thermal or turn on landing, you have an opportunity to recover before the stall becomes terminal. Washout is most commonly used when the airfoil is constant across the span to avoid stalling the entire wing at once.

Of course I'll defer to Mark since it's his design.
Old Aug 04, 2012, 03:28 PM
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I left washout out of the equation mostly because of the relatively long chord and thickness of the airfoil at the tip. I scaled the ribs in all directions when sizing and so are the same relative thickness for their chord. I did not find any issues with tip stalling when testing.

I think the term tip stalling is one of the most misunderstood terms out there. Often added regardless of if it is needed and often to much is used. It is usually used when a plane is flown to slowly in a turn and the inside wing stalls. Of course stalling is unavoidable ultimately as a plane flying to slowly will stall regardless. It is up to the pilot to keep it flying.

You can add some if you like. You guys are the builders and they are your planes after all.
Old Aug 04, 2012, 04:35 PM
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Thanks for the washout/tip-stall info......


Good info and interesting.

Mark Miller- I agree, I've seen some of the electric guys at the field call every single stall a "tip stall" and I've given up explaining it since I get that unspoken look of "what do you know, you're a woodie glider flyer, what a simpleton". Other than that, that's a great looking plane.

Lacquerhead - Interesting about the relative thicker airfoil at the tips, that's exactly what the 2M standard Spirit has, and even though I did thin and modify my airfoil on that completely modified Spirit 2M I just built, I did let it transition to a relatively thicker-toward-the-tip configuration. I think since I sheeted to the tip, I probably ended up with more washout built in than what I needed. I recently looked more closely at it and I think I have really close to 3/8". It turns buttery smooth fast or slow but I think it was overkill and 3/16" would have been possibly better, yet, it still stays in the air longer than anything I've built yet so I'm not going to mess with it or complain.

Thanks for the info-Paul
Last edited by Pauliwog; Aug 04, 2012 at 06:31 PM.
Old Aug 04, 2012, 09:36 PM
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Paul,

www.isthmusmodels.com

Buy some stuff so I can go to the NATS next year. I miss it.

Mark
Old Aug 05, 2012, 07:46 PM
Phoebusflyer is offline
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Full Scale Better! UOHHHH!
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I just did! I hope it helps!
Allen
Old Aug 05, 2012, 09:08 PM
Mark Miller is offline
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Thanks Allen,

The kit will be shipped tomorrow.

Mark
Old Aug 08, 2012, 01:08 PM
UberZogster is offline
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Be the duck. Whaaaa?
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I was looking at this picture and started wondering, what are you using 3400 grit paper on?
Old Aug 09, 2012, 01:39 AM
Lacquerhead is offline
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I use it to polish metal and plastic/putty on fine scale plastic models. I could see using 1200 grit before primer on a painted plane or 1200-2200 wet on primer or between color coats on a painted plane. Properly done paint can be lighter than plastic film. I have yet to do it properly though. I'm just not patient enough sometimes.
Old Aug 09, 2012, 06:59 PM
schrederman is offline
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Hot Dawg Glider Pilot
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3400 is the paper series, not the grit. That's actually 120 grit in the pic...

Jack... (Darth Trailer Trash)
Old Aug 09, 2012, 07:55 PM
UberZogster is offline
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Be the duck. Whaaaa?
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Okay, I was like 3400!!! What am I missing?


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