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William

Wing ballast stuck

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William

I've managed to get one of the lead wing ballast slugs stuck in my Pitbull 1. 

I can push it all the way in and then, with the wing vertical, shake the ballast to within about 2 or 3 inches of the exit but no further. Has anyone got any ideas on how I might be able to get it out? Not sure whether using some light oil or even graphite powder might help or whether it would make the situation worse 🤔.

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Andy_B

get a big woodscrew  and screw it into the lead 

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pete beadle

Hi William

Invert the wing, sqirt some WD40 down the ballast tube, turn the wing right way up, start rattling and keep rattling 'til you hear the "plop" as the slug drops out:)

Regards

Pete

BARCS1702

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William

Thanks Pete, will try the WD40 and if that doesn't work will try Andy's suggestion (I've never tried to drive a screw into lead - will experiment with some spare ballast  and see how it goes).

Many thanks

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Dave Elam

The woodscrew method does work.

Another could be to wrap some double sided tape onto a dowel end and try and get that to stick to the ballast slug.

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mtreble

Another option is to put the wing in a cold place for a couple of hours. This has worked for me in the past with brass ballast.

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Witch_1

You could try tape a timber block to the end so it can be tapped smartly on the floor without damaging the servo lead or pins or flap.

Personally I wouldn't put oil of any sort onto a GRP structure, especially at the wing root.

As a last resort the outer end of the tube may be accessible at the servo hatch to drill a small hole and poke a wire in.

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William

Thanks Mark, I did think of cooling it but it was about 6 degrees when it got stuck so not sure if I can cool it much more (large freezer maybe?). 
Nigel, thank you for that: I thought that I’d read that using WD40 and the like on carbon bike frames would weaken the structure but when I tried to verify it, the internet seemed to be split into dire warnings on the one hand and people that have used it for years with no ill effects on the other. I will today attempt to solder a screw to a rod and then see if I can get it to self-tap into the lead.

 

Many thanks for all the suggestions

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mtreble
1 hour ago, William said:

Thanks Mark, I did think of cooling it but it was about 6 degrees when it got stuck so not sure if I can cool it much more (large freezer maybe?). 

day trip to Scotland?☃️

  • Haha 3

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William

🤣

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isoaritfirst

First thing I try is cupping the wing root in the palm of my hand and smacking it down sharply onto the bench.

Try to start with the ballast at the far end of the tube so that it has time to speed up before hitting the troublesome area.

second is screwing something into it, as Andy suggested. I have a screw fixed firmly into the end of a carbon tube, so I can push it into the ballst tube to reach the end.

 

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pete beadle

Hi William

Also, it's not the cold temperature itself that matters, its the difference in temp between the stuck slug and the ballast tube that matters most innit! Back to basics, what!:yes::thumbsup:

Again, good luck

Regards

Pete

BARCS1702

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William

Thanks Mike, might try the  tapping method first and move on to more extreme methods if needed!

Pete: I did try running a hairdryer over the wing skins in that area but that didn't help and can't work out how to drop the temperature of  the lead inside the wing without cooling the wing! I think it would still work if I cooled the whole wing and lead as I imagine that the expansion coefficient of lead is a lot greater than carbon and resin but I could be wrong - I often am!

Thanks for all the suggestions, haven't tried anything yet as the weather was good for flying today so just flew with a slug of ballast in the opposite wing. 

Will attempt extraction tomorrow.

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mikef

I can't really help here but for interest,  the expansion coefficient of a carbon/resin layup depends on the the layup used (combination of fibre directions).   Pure unidirectional carbon fibre tends to get slightly shorter when heated.  The resin expands when heated.  By careful choice of fibre directions relative to the measurement axis, it is possible to produce a resin/layup combination that doesn't change length with heat.  Useful for dimension-critical applications i.e. in spacecraft that see large temperature variations.

I think cloth lay-ups will generally expand because the fibres are wavy and the resin will dominate the thermal expansion properties.

Back to a practical suggestion......

Have you tried whipping the wing around holding it by the tip to ‘centrifuge' the ballast out?  (Do this in a wide open space!)

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William

Very interesting about carbon and resin expansion - thanks. I could try a discus launch style swing in the garden but it might result in a large chunk of lead flying out (good) and landing goodness knows where (bad) and possibly hitting a neighbours window (very bad) or even the neighbour (disaster).🤣

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simon_t

Tapping method most likely to be successful. You can be quite brutal if you bang the wing root onto wood or something that yields just a little - be very patient and keep tapping and it will release in time.

Simon

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William

Thanks Simon, tapping will be the first method attempted👍

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taggarc

Had a 15ft carbon / fibreglass salmon rod stuck - two people pulling at each end - nothing.  Went home threw a big  pack of frozen  peas on it and after 15 mins was able to separate the rod bits by simply pulling with my fingers !  Worth a try. 

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f3fman
1 hour ago, taggarc said:

Had a 15ft carbon / fibreglass salmon rod stuck - two people pulling at each end - nothing.  Went home threw a big  pack of frozen  peas on it and after 15 mins was able to separate the rod bits by simply pulling with my fingers !  Worth a try. 

Shame he's only got cauliflower ;-(

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Greg Dakin

Hi William, 

I'm sure that you've sorted your ballast issue by now, but if not but my recommendation would be to source some wooden dowel from B&Q as close to the diameter of the ballast as you can reasonably get. Then cut it cleanly and coat the end with some  decent 5 or 30 min epoxy. Push it down into the ballast tube until it makes contact with the errant ballast slug and leave to cure. You should then be able to pull the dowel out with the ballast attached. Break the ballast away from the dowel, give it a quick clean and the job is done. 

Also worth noting that the sharp edges of the ballast tend to cause the sticking point, so a swipe across the pointy / edgy bits with a smooth file can perform wonders. 

Cheers, 

Greg

 

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