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Old Mar 02, 2013, 02:46 PM
chronic in training
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Originally Posted by pval3 View Post
are you all using the epp elevons or making your own? I was concerned about flutter as well as flex span wize creating an uneven lift . . .any ideas
I'd go balsa elevons covered in 5 mil lam film or so Phil
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Old Mar 02, 2013, 04:01 PM
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Agreed.
I've gone balsa aileron stock covered in 10mil lam film.
I've done Silicon hinges which I am hopeing will reduce flutter due to that bit of stiffness in the hinge.
I used baking paper again in the wing bed and ran a bead of silicon (as per this video) and cotton bud to finish it off. The bottom of the wing should result in a flush surface wing through to elevon.

Not sur how well mine stuck yet, still drying. I laminated the bottom of the wing outer cores and elevon first, leaving about a mil raw on both sides. The idea being that I get a nice flat flush surface.
I suspect I may need to apply a little more once it's dried.
I also PU'd the trailing edge of the EPP to give a nice solid surface for the silicon to leaver off.
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Old Mar 03, 2013, 10:46 AM
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Silicon hinge is a good idea, I have used it in the past and have had no problems with it.
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Old Mar 04, 2013, 03:47 AM
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hinges finally dried.
I added some more silicon tonight to smooth out any imperfections and strengthen up adhesion. I also used a razor blade to spread out some more on the bottom. I spanned from the wing TE across to the elevon. So ended up with a perfectly flat transition from TE to control surface on the bottom of the wing.

I will not cover the silicon at all. This way when it flexes it stays smooth. If you cover it, the tape or laminate will crinkle when the elevon is down.

So it will be fairly stiff. Which will reduce flutter. Neutral point will be normal flying position so the servos won't be working to hard.
Smooth is fast, I want fast
.
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Old Mar 05, 2013, 01:10 PM
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Starfire60 DS build

These photos show some of the prep work for the silicon hinges.

I cut away part of the outer panel TE before joining the wing. Cut for 38mm aileron stock.

on the core bed, baking paper again, and applied some PU glue to the TE, focusing on the bottom hinge point. To give a nice solid anchor point for the silicon.

I wrapped the paper around while it dried to achieve a fairly flat external finish and force the glue to expand in for strength.

Happy with results.
The silicon is all dry now, flush bottom surface.
It is a stiff hinge, but not enough to case any significant twist. The thicker hinge is Perfect for a DSer as I will mostly have only minor movement from neutral anyway. I doubt I will get any flutter on these
.
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Old Mar 05, 2013, 02:36 PM
chronic in training
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looks good Rick.. You ever been radared while DSing this plane? I know the skua's had flutter issues with the thin airfoils in the 100's .. have you ever had flutter yet?

thanks,

Gary
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Old Mar 05, 2013, 05:35 PM
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pictures

Hello
Here are some pictures of mine
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Old Mar 06, 2013, 12:33 AM
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looking nice and sleek pval
I see no prop cut out. Is this a pure sloper You found a hill to fly ?

Gary
My personal best so far (by radar) is 109mph on my SF41-PW51.

Flutter:
I haven't had flutter issues with my smaller starfire. I don't expect to on this one due mainly to the stiff silicon hinges.
I do get really bad flutter with my cut down windrider Bat. I haven't tried it since replacing the thin (flexy) control rods with more solid ones.
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Old Mar 06, 2013, 12:39 AM
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static balancing of the elevons

Just today I was corresponding with someone about flutter and the cause. You may be all over this Pval ?

static balancing of the elevons.
It uses a weight attached forward of the hinge to dampen the tendency to oscillate. Essentially with the control rod disconnected, the elevon will tend to sit up instead of drooping down. It's used on high performance aircraft (real ones).

I'm told, It's an easy retrofit so it shouldn't be difficult once you get the gist of it.
Try the following site and scroll down to Mass Balance for an explanation and movie.
http://www.pilotfriend.com/training/...ng/primary.htm

The balance weight must be at or near the extremity of the control surface where movement from flexing is greatest (near the wingtip for aileron, outboard for elevator and top of the rudder) for it to work effectively so attaching it to the control horn would most likely not work as well as it should. Balanced is OK but slightly overbalanced is better. That would pretty much kill any tendency to flutter unless the control surface is excessively flexible.



I did not know the true cause of flutter, so I found this very interesting.
Interested in your opinions and pictures/threads you can point to where this has been applied to a RC wing

Rick
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Old Mar 06, 2013, 05:51 AM
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more

Anothet
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Old Mar 06, 2013, 08:17 AM
chronic in training
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Anothet
looks good Phil. are you going to slope this one. I thought you did not have any slopes nearby so usually went all power.
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Old Mar 07, 2013, 03:26 AM
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Starfire60 DS build

Servo install.

I jumped the gun and assummed the outer TE was at 90degrees to forward. Its actually off a little. So I got my servos off angle slightly. Will have to make that up in the control rod, oh well.
I used my little homemade hotwire tool for the cut outs.

Installed on the underside so the servo arm is just below the top surface so I can cover it and only have a small slice out of the lam covering for the control rod

I run the servo extension plug up close to the servo in a small cut out. This helps heaps if I need to change out a servo. I only need to remove a small section of laminate
.
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Old Mar 07, 2013, 09:18 AM
chronic in training
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looks good Rick.

Quote:
Originally Posted by cleansurf2 View Post
Servo install.

I jumped the gun and assummed the outer TE was at 90degrees to forward. Its actually off a little. So I got my servos off angle slightly. Will have to make that up in the control rod, oh well.
I used my little homemade hotwire tool for the cut outs.

Installed on the underside so the servo arm is just below the top surface so I can cover it and only have a small slice out of the lam covering for the control rod

I run the servo extension plug up close to the servo in a small cut out. This helps heaps if I need to change out a servo. I only need to remove a small section of laminate
.
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Old Mar 07, 2013, 09:48 PM
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Starfire60 DS build

Here is the bottom of the wing, showing the servo under one layer of 10mil lam film and the silicon hinged elevon.

The servos are hot glued in on the sides only, so I can cut away the glue for servo replacement if required.
One must plan for the worst with a DS wing
.
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Last edited by cleansurf2; Mar 08, 2013 at 02:42 AM.
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Old Mar 07, 2013, 10:21 PM
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Starfire60 DS build

Removable fins

I will be doing removable coreflute fins like I did on my 41" starfire sloper SF41-PW51. But with the 60" Starfire I need to make it a twin fin so I can keep the fin size down and keep the anchor point as far aft as possible.

I have had great success with this fin mount method. I get zero fin twist of the mount, its rock solid. Makes for great transpotability and damaged fin replacement.

Sample Pics of my finished SF41-PW51 below.

I will post detailed how too pics on the 60" build soon.
.
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