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Old Mar 04, 2013, 02:49 PM
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vac bagging an epp wing like this may prove very difficult as epp is very porous and will suck in a load of epoxy . . I think you would be better served with the spray 90 and roofers cloth similar to the 48" mcw I put together . . .or the high speed version of the starfire . .lots of strength but plenty flexible to enhance the properties of the epp.
phil
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Old Apr 08, 2013, 05:47 AM
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SF41 DS Build

Back again with another fresh build.

I think this is my 7th Starfire build and no two are built the same yet
No different this time around. I have learnt heaps from DS rebuilds that has helped refine my built techniques with a big emphisis on performance and planning for repairs. Such is Dynamic Soaring

This build will be a cut down 41" PW51 version.
A heavier stronger DS build.
I have sourced some Fibre glass flat bar 11x4mm and will try it as a curved main spar.

* Now I'm into DSing, the lightweight build has had several breaks to the lightweight FG I-beam spars, so instead of strapping lead to the light airframe and pushing it over 100mph, I will swapp to the heavier build for the faster DS days.

I'm happy with the SF60 DS build silicon hinges but am doing a better hinge base this time around.

Here are photos of the outer panels prepared with a nice solid strait platform for the silicon hinge using 2mm FG rod using PU glue restricted to force it into the foam for good strength.
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Old Apr 09, 2013, 02:55 AM
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SF41 DS Build

Lay out pictures:

Inner and outer panels joined.
Battery and ballast trays fitted with plastic floors.
Fin mount preped.
finger holder hole preped.
Spar and component Layout planned.

Ready to join the wing halves
.
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Old Apr 09, 2013, 11:30 AM
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why the 41"?

Hey Rick,

Why did you cut the tips off? you just like the plane more responsive? I would think a 48" built stout for DS would also haul a$$.
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Old Apr 09, 2013, 04:21 PM
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I cut the middle 7" out (the thickest part of the wing).
Yes I like it responsive and the 41" has been my favourite all rounder. Especially frontside. Twitchy in the big DS loops, but then I have run it at some small tight DS sites that a 48" would be to big for. Need a variety of planes to suit the sites/conditions. The fleet just keeps growing

I will probably do another 48" for DS. As I trashed my 48" PW51 version, it may be savable but was not built for DS.

I will also try a standard foil as a 41" DS'r later down the track also. I expect it would be significantly slower, so probably lots of lead and lots of punishment
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Old Apr 26, 2013, 05:48 AM
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SF41 DS Build

Spar system

x2 fibreglass bar (14x4mm).
Used a grinder to rough it up for glue adhesion.
Also slimed it in the middle and ends to componsate for the wing profile.

I ended up adding 4mm fg rod along side the main spar where I slimmed it down for strength.

Plastic bar is to be glue bridged to the other 2 spars.
Slot and plastic bends ready to glue.
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Old Apr 26, 2013, 10:53 AM
chronic in training
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interesting... have a pic of whole wing with you spar setup?
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Old Apr 26, 2013, 05:05 PM
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SF41 DS Build - PU glue tips

Spar PU glue technique.

Some tricks I've learnt using PU glue:

PU expands, so:
Pros:
1. Excellent penatration into the foam for really strong & robust spar/foam interface.
2. PU has good flex.
3. Excellent Gap filling.

Cons:
1. Expansion means removal of excess dried glue or containment while drying.

-----------------

What I'm doing here is:
1. PU glue applied in the slot.
2. Yellow spar inserted.
3. Some small spaces on top to stop the spar pushing right up to the surface.
4. Non stick Baking paper layed down.
5. Cardboard cut-out over the spar to give a more solid pressure point than the foam bed.
6. Bed layed on top.
7. Weight distributed over glued area.
Note: The bottom bed also has cardboard and baking paper (otherwise the PU glue penatrates into the bottom bed, not good !).

After trying many methods, I find this the most efficent and best results
.
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Old Apr 26, 2013, 05:36 PM
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SF41 DS Build

Finished DS spar system.

The last picture shows 5kg supported across the center with very minor flex.
This thing is rock solid before even applying the 10mil lam film

Still suseptable to some wing twist, but should be fine.

This is going to be a very solid sleek DS wing.

Current weight with spars and fin mount: 268 gram
The additional build weight in the finished wing, plus the ballast option of an additional 300 gram, will give great DS speeds.

The right conditions should see me beat my PB of 128mph on the light weight SF41-PW51.
.
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Old Apr 27, 2013, 03:38 PM
chronic in training
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looks good thanks rick.
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Old Apr 27, 2013, 08:19 PM
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clean surf . . . I see that your weights are getting the same use mine are
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Old Apr 28, 2013, 02:05 AM
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Hi Gary & Phil. Fellow RC addicts

Got to use those weights for something now Phil

This build is coming along well. Will be a really fast wing I think
I am however at the stage now where the time it takes to build up a foamy to the performance standards I am after is becoming to time consuming. The last few starfire core wings have probably taken 30-40 hrs each in hands on build time. I do lose time in contemplating engineering options, but that's how my technique has improved over time for better results.

After this, I will try and finish off my cnc hotwire cutter so I can make a prototype foam wing I've been contemplating. I can use a foam plug to make a fibreglass mould, so I can start experimenting with moulding techniques.
Lots of work, but great potential for faster builds on high performance designs.

Rick
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Old Apr 28, 2013, 05:47 PM
chronic in training
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L.A. beautiful san fernando valley
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Quote:
Originally Posted by cleansurf2 View Post
Hi Gary & Phil. Fellow RC addicts

Got to use those weights for something now Phil

This build is coming along well. Will be a really fast wing I think
I am however at the stage now where the time it takes to build up a foamy to the performance standards I am after is becoming to time consuming. The last few starfire core wings have probably taken 30-40 hrs each in hands on build time. I do lose time in contemplating engineering options, but that's how my technique has improved over time for better results.

After this, I will try and finish off my cnc hotwire cutter so I can make a prototype foam wing I've been contemplating. I can use a foam plug to make a fibreglass mould, so I can start experimenting with moulding techniques.
Lots of work, but great potential for faster builds on high performance designs.

Rick
Rick,

Yours and Phils contributions to Jeff finely handmade foils is to be admired. I am excited as I currenty have 5 gliders rtf.. and 4 power planes.... almost up to my 6th glider..may have to go conventional glider after that then hopefully my starfire.. the look of these is just so cool. thanks for all your posts (both of you)

Gary
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Old May 03, 2013, 03:30 PM
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SF41 DS Build

thanks Gary.

Using bigger thin wing servos this time. Bench testing seemed good for resolution, slop and centering

Used My old faithful hot wire tool as usual.

Bottom mounted, flush. Easy access for replacement and cleaner top surface as the top of the arm should be below the top surface.


These are the servos I'm using this build.
.
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Old May 26, 2013, 05:28 AM
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SF41 DS Build

finally got some more done.

- A few strips of hinge cloth applied with 3M77 to support the silicon hinges a little from tearing in impacts.
- 10mil lam film both sides of the balsa elevons.
- Servo extension lead bay next to the servo for easy servo replacement.
- Minimum cable runs kept clear of the spar where possible, marked and photo archieved to assist with repairs if needed (it's a DS plane).
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