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Old Nov 09, 2014, 01:36 PM
Where is the inspiration
wdeighton's Avatar
Moira
Joined Feb 2006
831 Posts
Bit of an update

Its been a while now, but there was some more groove armada action about 2 to 3 weeks ago. Not mega winds but enough for a 197mph.

I have been a bit off this game for a while. lots going on at work, spending more time with the family and not knowing what to do next.

The damaged centre section has got me rather pee'ed off. The damaged part is the part that cost me the most to get machined. And now I think I need to get it re-machined. Not sure if I have said this yet, but I would not laminate corian again and cut through the first layer. If I do land up making a new top section it will be done from epoxy board. if I had done this in the first case, it would have saved me and Mike a lot of time and money.
I have also considered taking a plug from the damaged cavity, I can then tweak it and then make a new core. But that on its own will cost a fair bit in time and money and could also go wrong with the chance of bubbels.......
I wish I was better at this game, But I guess it is just a hobby.

On a happier note, I am now moving on with the second set of wing tips. I have ordered the required servos, voltage regulator and ext bearing kit (This is getting the as supplied by T9)
This set of wing tips will be a touch heavier as it a stronger layup in the skins. and I will also put the spars in better so I can get wipers on the ailerons.

Cash is really an issue for this project, so unless I can make some deals, certain things are going to slow down drasticly.
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Old Nov 09, 2014, 06:10 PM
R.I.P
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Australia, QLD, Toowoomba
Joined Jan 2010
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Keep plugging away Will. Don't be afraid to go for a heavy glass layup- you can save heaps and still have a super fast plane. Save the carbon for the spar caps and drag spars. I have been using stitched triaxial glass for a while now and it is very cheap and strong.
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Old Nov 09, 2014, 08:11 PM
PB of 733kph
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Christchurch, New Zealand
Joined Jul 2005
5,716 Posts
I know how you feel Will. You are doing an awesome job though.! Looks the perfect model for where you fly
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Old Nov 30, 2014, 09:12 AM
Jonathan Wells
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Joined Feb 2008
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Hey Will,

How are the new tips coming along, popped them out yet?
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Old Nov 30, 2014, 11:20 AM
Where is the inspiration
wdeighton's Avatar
Moira
Joined Feb 2006
831 Posts
Quote:
Originally Posted by jonathan4000 View Post
Hey Will,

How are the new tips coming along, popped them out yet?
Nope. But I closed up the mould last night.

Its in the warm box at about 25 to 30 degree c

As often is the case with us amteures things go wrong, last night I ran out of micro baloons. the sploodge was quite stiff and I thought would be ok, but after applying all over, I noticed it had run down the leading edge further than I would have wanted.

So I bolted it up and put it leading edge down hoping it will all run forward again.

Plan to pop it next week some time. I always think the longer we wait the better. as the more time for cross-linking. Fingers crossed.
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Old Nov 30, 2014, 06:36 PM
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Australia, QLD, Toowoomba
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Will that should work well. I always use runnier splooge in the LE and stand it on the front edge after closing, hoping it makes for a stronger LE
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Old Dec 02, 2014, 06:04 PM
Where is the inspiration
wdeighton's Avatar
Moira
Joined Feb 2006
831 Posts
Happy

I popped the second set of wing tops tonight, and the results are good. Not perfect. I knew the paint had issues, and after the centre section I new the roots wouldn't be too good.

the leading edge seems ok. there was splooge to be removed all along the wing, so I think I have a good but joint as a minimum. I was thinking of injecting some expanding epoxy if I start to have any issues.

Strength Very good

Saying that, I haven't cut the aileron free, but I think they will be good for some serious DS. (Saying that the lighter tips still had a lot to give. No sigh of flutter our bend)

Weight 370g vs 300g so a good 25% increase in weight which is good in my opinion. Even in lightish conditions I still felt that it could use more weight, but adding the ballast was a bit too much.

This brings the complete mass up to 3.3Kg5 and 4.34 Kg with balast
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Old Dec 02, 2014, 06:32 PM
Jonathan Wells
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U.K.
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Looking great Will, canít wait to fondle the new tips.
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Old Dec 02, 2014, 08:45 PM
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New Zealand, Wellington, Porirua
Joined May 2006
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Quote:
Originally Posted by wdeighton View Post

As often is the case with us amteures things go wrong, last night I ran out of micro baloons.
should you be using Micro balloons?? I was always under the impression that micro balloons were for filling and glue powder was for gluing

I am no expert though

Jono
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Old Dec 03, 2014, 01:22 AM
AvB
Wind, hill, ... I'm keen ...
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Australia, QLD, Woody Point
Joined Nov 2006
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Hey Will, congrats mate. Pat yourself on the back for the paint issues. They're the mark of the true workhorse homebrew DS ship.

I'm no expert - most manufacturers use microballoons, but in my experience the mix can be brittle. Cotton flock (microfibres) completely stops brittleness and increases adhesion, but one problem can be that if it flows into the flange when you close the mould, the fibres have some thickness and can hold the flanges apart slightly. I have to say I really strongly recommend trying a really strong epoxy gel. They're commonly available, used by woodworkers and boatbuilders etc. (the one I use is Techniglue), also for structural adhesives and even concrete adhesives. The gels are really easy to mix and syringe as a stand-up bead behind the LE and smeared on the TE. Gives the best of hardness, adhesion, ease of use, and squashes flat in the flange. No need to worry about getting the layup right up to the lip - let the Techniglue fill into the tip of the LE and it's like having a steel bar behind the LE!

Small amounts of Techniglue are expensive, and one of our suppliers sold me a cheaper alternative , called Compset 221. When I opened it a few months later it had crystallized. I took it back and they gave me a much bigger container of what they said was a a similar thing called Compset 121. I thought it was great, and I have tons of it, but I found that it remains very flexible when cured. It doesn't seem to be a problem for joining the wing skins as far as I can sense, but I don't like the fact that the leftovers in the cup are bendy. I think it could be an issue if you used it between skin and spar. Some of the gels have additives to give flexibility, which can be good with furniture etc to stop the epoxy cracking. But for our uses I think the rock hard ones are the best.
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Old Dec 03, 2014, 08:11 AM
He who dares ... repairs!
Hobster's Avatar
Joined Jun 2005
683 Posts
I use a soft foam weather strip (about 1/4" square, comes in a circular reel, sticky on one side) stuck just aft of the LE. Prevents the splooge from running down the mould and will squash up to nothing. I use it in wing and stabs, both mould halves.
Also when mixing up microballoon epoxy mix, I add a small amount of fumed silica to gel the mix. Not too much though or it might be hard to get through the caulking gun
Wing looks good Will - hopefully see you Sunday at the show
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Old Dec 03, 2014, 01:51 PM
Where is the inspiration
wdeighton's Avatar
Moira
Joined Feb 2006
831 Posts
Hello All

I feel the same about Micro Balloons. I started to use just milled fibers or cotton flocks but found it still needed a bit of balloons to bulk it out. But if you use too many fibres it doesn't flow out of places like spars and trailing edge which can then give you a door stop of a trail edge.

So now I use a 10% mix of fibres. IMHO just enough to stop the balloons being too brittle.

I would like to try Techniglue.

Thanks for the comments.

@Steve, Not sure about the show at the moment. I did want to shift some models to improve the modelling funds, but skirrid looks like it could be brilliant. 200mph for sure, and he GA hasn't been over 200 as yet.
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Old Dec 03, 2014, 03:20 PM
More like crunchman....
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United Kingdom, Cheshire East
Joined Mar 2007
919 Posts
Heck, Will, Met Office is giving max 15 g28 & part rain for Skirridabouts. Not going to blow anyone's socks off.
Don't wish to miss you at the weekend but, if you insist on spending Sunday getting wet, bags-I your acommodation Saturday night at Ian's, much better than a hard floor for an old codger like me
I've your D80 fuz straightjacket to return (thanks for the loan ), I'll leave it with Ian if you're absent.

BTW, Id thought inclusion of microballoons in epoxy made the bond less, not more, brittle. Guess I've been fixing servos incorrectly for some years.......
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Old Dec 03, 2014, 10:50 PM
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Australia, QLD, Toowoomba
Joined Jan 2010
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I've found micro balloons very brittle also. I find a mix of cotton flocks and cabosil (silica?) very nice, as its strong and doesn't run away.
Micro balloons would be ok for servos I reckon as you want them to pop on a bad landing rather than strip gears etc.
cheers
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Old Dec 04, 2014, 04:21 PM
AvB
Wind, hill, ... I'm keen ...
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Australia, QLD, Woody Point
Joined Nov 2006
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Someone said to me once that laminating resins are designed for that purpose ... thinned and enhanced with additives etc to make them suitable for wetting up cloth. If you want an adhesive, use an adhesive base epoxy. Gel epoxies are designed for bonding and joint strength. Also there are liquid base epoxies that are cheaper than laminating epoxies and it's not a bad idea to buy a few litres and keep it on hand just for making splooge etc as they're more suited to it than laminating resins.
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