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Old Jul 07, 2014, 09:11 PM
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United States, OR, Tualatin
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Question
Adding Washout to Wing Cores

Ok guys: How does one add wash out to the wing tip of cores that have a common base when cut? So the hot wire cut cores have a top, middle, and a bottom, which is the top of the second core. Other than cutting the middle bed in half, I do not know how to get a bottom bed for propping up back of the wing tip for wash out.

Any other solutions?
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Old Jul 07, 2014, 09:21 PM
Crikey never leave beer behind
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Mt Annan Sydney Australia
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Tom I dont follow ? Are using 1 or two templates ? as I cut washout in by lowering the l/edge of the tip Template from the rib center line marked on the foam block ,then it doesn't matter if your cutting in 1 block or 2 separate blocks
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Old Jul 07, 2014, 09:51 PM
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Steve: The cores were cut by some one else with out wash out. The center bed is the same thickness full length of the core. I agree that the best time to put in wash out is when you cut the cores, but mine did not come that way.

there is enough material in hte center bed that is acting as two bottoms, that I could cut it in half on my table saw by using the fence and making two passes, being sure that the same side is against the fence when I make the second cut. If I had a band saw, I would need to make only one pass, using a fence.

Tom
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Last edited by TomFlyer; Jul 08, 2014 at 01:20 AM.
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Old Jul 07, 2014, 10:20 PM
Crikey never leave beer behind
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Mt Annan Sydney Australia
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are you bagging the wing ? if so put some wedges under the L/edge at the root and keep the tips flat and vac it down ensuring a bit extra weight at the tips to kep them flat whislt the root section L/edge is raised
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Old Jul 08, 2014, 12:44 AM
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I think the most acurate way to do it would be to hotwire blocks with the washout, then spray adhesive it to your beds. Full span support so less chance of a curved te. and easier to make all the same. Maybe one of the core cutting companies would do it?
James
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Old Jul 08, 2014, 01:26 AM
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Quote:
Originally Posted by Redfarren View Post
I think the most acurate way to do it would be to hotwire blocks with the washout, then spray adhesive it to your beds. Full span support so less chance of a curved te. and easier to make all the same. Maybe one of the core cutting companies would do it?
James
Hot wire cutting the center bed would be the best thing. I will need to find some similar foam to practice on first however. I have some lap siding that might make a good bed for the wash out. Just need to get the angle right so the back of the wing tip is 1/8" higher.
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Old Jul 08, 2014, 01:56 AM
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I'm sorry I didn't read your post clearly, yes cutting center section into 2 beds would best. I do like 4 beds not the center double ing as both surfaces
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Old Jul 08, 2014, 04:25 AM
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Ailerons rigged with a bit of reflex serve as washout. There is a slight aerodynamic penalty, but shouldn't be a problem with a sport slope model.
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Old Jul 08, 2014, 05:18 AM
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Derbyshire, UK
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Do you even need the washout? If the tip chord is more than about 60% of the root chord, tip stalling won't be a issue.
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Old Jul 08, 2014, 06:37 AM
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I'm with the Shed, Tom, before wondering how, you should ask why.

Dieter Mahlein, ShredAir
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Old Jul 08, 2014, 07:09 AM
guamflyer - Avid Sloper
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pretty much all the time I put the washout in when i cut the cores..other stuff could work..but like the guys say if the tip chord is wide then not really a problem
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Old Jul 08, 2014, 08:09 PM
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The wing sweep will also seriously affect whether or not you need washout. Straight wings generally don't need it, Slighty swept rearward wings can usually get away without any. But a highly swept wing will need washout regardless of the root to tip ratio.

98% of my PSS birds have no washout. My F-15, F-86, Mep1101 and my Caravelle all have washout.
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Old Jul 08, 2014, 08:36 PM
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Quote:
Originally Posted by TFLG View Post
98% of my PSS birds have no washout. My F-15, F-86, Mep1101 and my Caravelle all have washout.
So you have 200 PSS planes...

: )

: )

: )

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Old Jul 08, 2014, 09:05 PM
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What plane Tom
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Old Jul 08, 2014, 10:40 PM
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The wing in question is for a Quicksilver that has a 8.5" root and 6" tip and a straight trailing edge. So the 2.5" taper is all in the LE. Airfoil is the RG14 8.49% thick,
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