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Old Apr 05, 2012, 07:35 PM
Entropy is happening!
Jim.Thompson's Avatar
Australia, NSW, Bellingen
Joined Aug 2008
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Jonathon,

No I had not seen that thread, thanks for the link.
For the odd large size tube that method of Target's, or a variation of it, is the way to go I think. However, for the smaller diameter tubes right down to 3 mm, getting rolled paper and tape out of it after would be a very difficult job. Also, the purpose made glass or carbon sleaving is such a breeze to use, with diagonally woven fabric etc.
The downside for us on the other side of the world (Aus), is the postage for this sleave from Soller Composites!
The spiral wound strips of drop sheet plastic pulls out without a hitch.

I've bookmarked Target's thread to read more thoroughly later.

Jim.
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Last edited by Jim.Thompson; Apr 05, 2012 at 10:45 PM. Reason: size correction
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Old Apr 21, 2012, 04:46 AM
Entropy is happening!
Jim.Thompson's Avatar
Australia, NSW, Bellingen
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Tail surface plugs.

I have now vac bagged the tail surface plugs. I sanded them roughly this afternoon and tomorrow will splooge fill the leading edges.
Then I want some fine weather to start priming and surfacing them. I will mask off the wing where it will be glued to the fuselage and then prime/surface the rest of it. Then glue to fuse and contour the fillets to suit.
Then all will be primed as one part before I take a saw to it and cut it up into 5 individual pieces! Should be fun!
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Old Apr 27, 2012, 12:22 AM
Entropy is happening!
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Primer/surfacing.

I've started the long process of piming, filling sanding (repeat......) process to surface up the flying surface plugs. I ran out of nitrocellulose automotive stop putty so I mixed some talc with acrylic primer. I'll try it out later.

Jim.
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Old Apr 27, 2012, 06:12 AM
R.I.P
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Australia, QLD, Toowoomba
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Nice Jim. Id be keen to see how your talk/ primer mix goes, cause I hate that stop putty. It takes forever to dry and always seems to shrink back.
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Old Apr 27, 2012, 05:29 PM
Entropy is happening!
Jim.Thompson's Avatar
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Originally Posted by josh18 View Post
Nice Jim. Id be keen to see how your talk/ primer mix goes, cause I hate that stop putty. It takes forever to dry and always seems to shrink back.
I haven't experienced that problem Josh. It is only intended to be applied in very thin, multiple applications. Most of the filling of large voids/depression is best done with other fillers like epoxy/microspheres (splooge) mix. Or of course, the polyester "Bondo".

When using stop putty for finishing, I typically apply two or more applications and wet sand them in the one day.
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Old Apr 27, 2012, 10:23 PM
I hate propellors
emufingers's Avatar
Australia, SA, Normanville
Joined May 2009
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Josh, think about it this way. Stop putty and single pack paints dry by evaporation of the solvent. They are therefore prone to shrinkage, molecule fly off into the air. The two packs like bondo, bog, plastibond and all of the epoxy mixes you make up dry by chemical reaction and are therefore less prone to shrinkage, The polyester family contain styrene to control the denstiry of the mix and that evapiorates, encouraged by the heat generaled by the chemical reaction. The polyesters therefore have more shrinkage than the epoxies which have only small quantities of solvent.

With solvent drying materials it is best to use thin mutliple applications as this helps the solvent evaporate resulting in quick drying and you adjust for shrinkage on the way because the previous application have already shrunk.

The reason why the polyesters are populat is their reaction time is much quicker and the nature of the polymer bond makes curtting them back easier. It is possible to use a plane ( not a flying one a sharp one) to remove excess material very quickly. The crash trade is a special grated type tool.

Jerry
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Old Apr 29, 2012, 05:45 PM
Entropy is happening!
Jim.Thompson's Avatar
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Quote:
Originally Posted by josh18 View Post
Nice Jim. Id be keen to see how your talk/ primer mix goes, cause I hate that stop putty. It takes forever to dry and always seems to shrink back.
Josh,

The talc/primer mix sands very easily, easier than stop putty. I've only started using it, but it looks very suitable for filling and surfacing up plugs. I would not use it for models because the talc is heavy. I'll be using stop putty for alternate applications for the colour difference. It's easier then to keep track of what is to be removed when sanding and when a coat is sanded through etc.

Jim.
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Old Apr 29, 2012, 06:41 PM
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Great to hear jim, how long does is tend to take to dry? You should try using a guide coat to see what you've sanded- it makes getting a smooth flat finish super easy.
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Old Apr 29, 2012, 09:59 PM
Entropy is happening!
Jim.Thompson's Avatar
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Originally Posted by josh18 View Post
Great to hear jim, how long does is tend to take to dry? You should try using a guide coat to see what you've sanded- it makes getting a smooth flat finish super easy.
It dries quickly, I can sand it in an hour in fairly good conditions. But it's similar to the stop putty, if you put too much on, it will take many hours or longer!
I will use the guide coat when I start to approach the finer stage of the process. At this early stage, I can clearly see where I need to fill, where I need to sand and when to stop. This is most important!
I'm using long sanding boards with wet and dry paper stuck to them using spray adhesive.

I like the way this mix sands so easily. Wet sand of course, just repeating here.

I'll post some pics later. I'm going out for a fly now as the southerly is in!

Jim.
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Old May 05, 2012, 07:01 PM
Entropy is happening!
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I now have to set up my incidence alignment jig (patented ) as I did in post #174/174.
I'm waiting for a morning or afternoon clear of commitments to do it. I still have the sticks and stuff for it stored in the shed, so should not be a big job.
On the prototype, I managed to get the decalage set up perfect and it will be even more important this time. I seem to have a good "eye" for doing these sorts of jobs.
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Old May 11, 2012, 06:28 AM
Entropy is happening!
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Bad news and good news.

In my haste and eagerness to glue the wing plugs on the fuse, I failed to check the incidence with reference to the fuselage mid line. It's very slightly negative incidence now which is not good. I don't want the tail to drag in flight. So, I've decided to cut the fuse off the wing and take the opportunity to shape a new fuse.
I have long since been less that satisfied with the excessive "camber" in the fuse shape. I'll shape it again, with less arch or "camber". This time I'll use laminated MDF. I can keep the nicely shaped fillets on the wing, and just cut the new fuse in between the two glued on fillets. Don't know if that makes sense or not, but I'll post pics when I'm doing it.
I hope to get back to it next week.

Jim.
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Old May 11, 2012, 10:04 AM
Just fly it!
wyowindworks's Avatar
Cody, WY
Joined Nov 2007
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The fuse is negative to the wing when it's at zero? The wing probably won't be flying at zero anyway. If you know the wing wing area, airfoil, expected cruize speed, and weight you can calculate the AoA of wing to generate the required CL.

Adam
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Old May 11, 2012, 04:54 PM
Entropy is happening!
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Originally Posted by wyowindworks View Post
The fuse is negative to the wing when it's at zero? .............

Adam
No Adam. The other way around. The fuse is very slightly positive when the wing is at zero. About 5 mm down at the tail.

I must not have explained properly in the previous post.
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Old May 11, 2012, 05:05 PM
Just fly it!
wyowindworks's Avatar
Cody, WY
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Quote:
Originally Posted by Jimbello View Post
No Adam. The other way around. The fuse is very slightly positive when the wing is at zero. About 5 mm down at the tail.

I must not have explained properly in the previous post.
Ahhhhh.....I see.

I wouldn't get too bent out of shape. Ever notice the attitude of the fuse when flying in airliner....and these guys are psycho about fuel efficiency and drag.

The air follows along the fuse just it it follows a wing airfoil. Small angle changes make almost no noticeable difference in drag. The drag only really rises if there is flow separation. The drag on a wing will change with angle change because the lift changes. Lift=drag....typically anyway. If the fuse isn't generating lift then small angles changes are not noticeable. Also, you can only have the fuse at the optimum angle at one speed. Change the speed and the angle of the fuse will have to change.

I personally wouldn't sweat 5mm.
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Old May 11, 2012, 05:14 PM
ERS....Energy Retention System
timbuck's Avatar
gold coast australia
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+1..
Don't think you will see that when in flight..
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