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Marc RC pilot

like a fool, and for some reason, I decided to hold my Longshot at the wing tip whislt lifting it like a  plate and now have a lovely crease/floppy wing tip where it failed under the stresss...=)  The inner foam seems to be split apart inside by crease mark.

I'm looking at a quick fix and have carbo tows/raisin and epoxy etc for repair. Thinking of running some carbon tows around the area/existing carbon spar tow etc

Any advice is apreciated.

Many thanks

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Neil Harrison

Wow....looks like you did a great job of that 🙈

Okay, so it looks to me like the spar caps and shear web have broken.

Good news it’s a really simple repair,  I would start off by making a thin vertical cut/slot spa wise along the spar cap.  If you have got any carbon cloth, then wet a small piece out and cure it between 2 pieces of polyurethane on a very flat surface with a heavy weight on.  Once cured, cut a  piece to glue into the slot you made, make sure you cut so the orientation of the weave is at 45 degrees to the vertical and of course make sure the wing is straight and true.  (the slot you cut should only be as wide as the cloth or tow lattice). At this time also inject some resin into the break line in the foam. If you haven’t got any carbon cloth then you can make a lattice from the carbon tows.
Once cured the next job is to sand down the spar caps top and bottom about at least 10mm each side of the break, then just wet out carbon tows and glue them in place  trying to keep the wing profile.  You need to then  to add glass cloth over the broken wing skin.
 

*Do not use too much resin when setting out, this add no strength only weight.  Make sure you dab paper kitchen towel on the carbon tow/cloth and glass cloth to remove excess resin.

**You might know already, but do not use CA!!

 

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Marc RC pilot

Yes a proper doughnut I am.....Certainly will not hold a dlg like serving up a roast dinner again.....=)

Thank you Neil for great instructions/advice! 

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Marc if you need some cloth I’ve got some you have , or if you’d rather I can pre preg some for and post it as a rigid sheet.

dave

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Neil Harrison

I should have mentioned, when you sand the spars you need to graduate it, so exaggerated looking from the leading edge it is a ‘V’ shaped.

This will spread the load of the repair into  the existing spar.

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Marc RC pilot
20 hours ago, Dave H said:

Marc if you need some cloth I’ve got some you have , or if you’d rather I can pre preg some for and post it as a rigid sheet.

dave

Hi Dave

 

Thank you so much for your kind offer sir!

I placed an order for some carbon cloth from Superfly/Neil: 

60g Carbon Plain Weave, Size: A5(0.03m2)

I should of checked if this is the right stuff with you chaps first....Did I get the right one Dave?

 

19 hours ago, Neil Harrison said:

I should have mentioned, when you sand the spars you need to graduate it, so exaggerated looking from the leading edge it is a ‘V’ shaped.

This will spread the load of the repair into  the existing spar.

Thank you Neil 👍

 

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  • 3 weeks later...
Marc RC pilot

 Can J use clingfilm for made up spar? 

I've got some micro glassballs to ad to epoxy and thinking of using it to fill a couple of leading edge dents and perhaps the dent left by wing tip fold. Tis ok?

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Marc RC pilot

Prepped area (sanded/epoxied crack/area, filled gaps etc with epoxy microball filler, carbon fillets in situ before start bonding.

Also reset aileron control horn which was out of alignment and filled in a few dings on leading edge..

All reinforcing spar cloths ready to go.

Question please: 

I made 2 carbon wing fillets and would like to use them sandwiched together as they fit nice and tight...

Is ok to epoxy them together and into slit in one go ?

Btw, i made up some carbon fillets out of tape as an experiment and proceded to check there stifness/tolerance under the intended  specific load... was night and day...The importance of latice/type/direction is crucial for specific loads(tape carbon snaped very easy)

 

Thx for help chaps

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  • 3 weeks later...
Marc RC pilot

Carbon in place both sides and ready for final sand.

Seems very strong. Do I need to place glass fibre? 

 kst 08s to install.

Ailerons control horn reset/made secure.

Thx for help :)

 

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  • 1 month later...

Wing tip repair done. Looks a bit messy but all smooth and feels incredibly strong. Just sorting out wiring/new servos/servo bays etc. I added some epoxy/micro balloon mix to help seat the servos(cling film method) and will use tape/epoxy in once all soldering done.

Realy looking forwards to having slop-free/solid controls on ailerons (original servos had issues...). I got a couple of spare kst 08's which I am tempted to use/replace those in fuz.

Thank you all for help and advice. Realy apreciatted :)

 

 

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I must say  that after such a long layoff from flying/RC, this old Longshot has been the perfect dlg learning/introduction model on many levels for me; weather it be programming open tx, controls on the glider, repairs with carbon, soldering and of course actualy flying (need more of that). Early days still and learning from my mistakes and successes. 

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managed to get servos installed yesterday. Soldering these tiny wires is no easy task...but I started to get it down on my last few solders.

Lessons learned soldering:

Take your time setting it all up then go in/get out quick on the soldering,

Don't forget to have heat shrink tubes in place and of correct size or you will end up using yellow wing tape....

Adjust temp to suit job/wire size

Heat the wire and not the solder when making the wire connections so that the solder gets sucked through the joint making for a better/neater connection.

Do research/YouTube videos for help on techniques/methods

 

 

 

One thing that imho is crucial and saves potential damage is to ensure that all servo throws are dumbed right down (servo weight) to start with and increased/tweak accordingly. Do NOT link servos to horned until you are happy that all flight modes and settings are within servos safe operating range of movement. I did setting up with servos taped in to be sure. Thank god I did as one of them popped out of its bay when I forgot to re-set my failsafe settings and tried it...phew, lucky one, could have stripped gears/wrenched control horn off aileron etc

The main thing was to set the physical control link geometry as true as you can get it which makes settings the software control setup almost a pleasure.

I've got to tidy control rods and do a final settings tweak and she be good to go.

I still cannot get over how good/precise the kst servos are compared to what I had...like night and day. Will post video of ailerons working asap, unfortunately I got to get up for work....Narrrrrrrr 😢

Thanks again for 

 

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Does anyone know what gauge size the control rods are? I snapped a little to much off existing one as I tried to re-bend it... Another lesson learned.

 

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Couple of short vids showing initial aileron control/test settings (I have since dialled in all the numbers/throws accurately).  

Looks like site does not support MP4 video(?), will try something else later, apologies.

 

I had to make adjustment on one of the servos to counter for a short control rod....

Just got to tidy up control rod ends/ad on some heat shrink to the ends, apply some superglue to a slightly enlarge control horn hole (which was translating into approx. 1mm of slop to its aileron)

 

Last things to do are placement of RX/antennas (going to place it in fuzz under wing area allowing for more room up front/less messy) and balancing glider cg and lateral balance (to compensate for wing tip repair).

 

 

 

PS I have a volume control setup on a dial/TX as the lovely Frsky lady can get annoying 😃  

    

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Re-maiden success and she even came back home in one piece :) 

The repair feels solid with no issues, touch wood.

A few little tweaks here and there to do, but she soared well. Dare I say it, I got "caught"  in a couple of thermals and got up to 165m before I kicked in flaps...Well impress with the sharpness of ailerons/servos. I will defo replace the ones in fuz with kst 08 as the old servo's centrering is a bit of an issue on the elevator (not the best place for that to happen).

Was the perfect day for a maiden, winds calm, Scrubs park like a ghost town, and so silent everywhere.

Thank you for all your help gents and for making my day/week/month...! 👍 

 

Quick vid my m8 took of me launching (70%)

(will post through YouTube link as this site doesn't seem to support Mp4 downloads)

 

 

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