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Slingsby Petrel 3.4m - ChrisWilliams - PreBuildQuestions

General discussion on any topic which doesn't have a natural home on any of the other boards.
Mick666
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Joined: 03 May 2019, 22:30
Location: UK

Slingsby Petrel 3.4m - ChrisWilliams - PreBuildQuestions

Post by Mick666 »

Hello

I'm about to start a CWilliams Slingsby Petrel 3.4m. I've been modelling for 40 years but this will be the largest model I've built to date. I've bought the laser cut option with extra wood from a well known supplier. Bit concerned about the density of most of the extra sheet wood, which goes up to 20Ib.

So for a model like this, what would the usual form, wood density wise, for areas like 1/16" planking and LE sheeting etc. I realise its horses for courses on different areas of the build but I'd rather not be dipping into my own stash if the accepted form says 15Ib is fine. lol, I have to manage the old balsa stash carefully these days :D

I would say that the wood in the regular short kit and the laser cutting is all very good. Just the additional wood pack thats got me wondering.

Any help appreciated.

Mike

PS Most of my wood stash has been built up over the years around building free flight competition duration models so I think of 8Ib as getting a bit heavy :)
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Cliff Evans
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Re: Slingsby Petrel 3.4m - ChrisWilliams - PreBuildQuestions

Post by Cliff Evans »

I think Chris says that his was about 8.5Lb in weight. At that weight, it flies very well. The problem with wood stock at present is that there is only medium to hard balsa available, which in all honesty should not prove to be a problem. I personally don't think that a little extra weight will be a problem with the wing section used. I hear all the time modellers say "it needs to be lighter", more often than not, I feel that the extra bit of weight makes a much better model. With the Pat Teakle range, for instance. I was always being asked to produce epoxy fuselages as they were lighter. When I did make one, the model had to be ballasted up to the weight of the polyester fuss to make it fly anywhere as near the original.
Saving weight is not always the best thing to do with these gliders.
https://lasercutsailplanes.co.uk
https://patteaklegliders.co.uk
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chris williams
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Location: Blandford Dorset

Re: Slingsby Petrel 3.4m - ChrisWilliams - PreBuildQuestions

Post by chris williams »

I have never found much use for soft balsa, probably because it would fail to survive my landings. I recommend hard balsa for the wing sheeting, otherwise you might need more wing ribs to prevent putting your fingers through. The ply planking on the fuselage is a pain to apply, but super-tough and will laugh at rough slope landings...(Having said that, Trevor successfully planked his in balsa and made a saving in weight, but, then he knows how to land properly)
Mick666
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Joined: 03 May 2019, 22:30
Location: UK

Re: Slingsby Petrel 3.4m - ChrisWilliams - PreBuildQuestions

Post by Mick666 »

Hello

Thanks for the feedback, I’ll not overthink it too much then :)

Learning all the time.

Cheers

Mike
Mick666
Posts: 5
Joined: 03 May 2019, 22:30
Location: UK

Re: Slingsby Petrel 3.4m - ChrisWilliams - PreBuildQuestions

Post by Mick666 »

Hello

Would this be the right piece of kit for the wing joiners?

Cheers

Mike

https://www.gliders.uk.com/12mm-x-2mm-S ... nfo/GLB12/
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Cliff Evans
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Re: Slingsby Petrel 3.4m - ChrisWilliams - PreBuildQuestions

Post by Cliff Evans »

Mick666 wrote: 04 Aug 2022, 22:20 Hello

Would this be the right piece of kit for the wing joiners?

Cheers

Mike

https://www.gliders.uk.com/12mm-x-2mm-S ... nfo/GLB12/

Yes
https://lasercutsailplanes.co.uk
https://patteaklegliders.co.uk
Mick666
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Joined: 03 May 2019, 22:30
Location: UK

Re: Slingsby Petrel 3.4m - ChrisWilliams - PreBuildQuestions

Post by Mick666 »

Hi

Couple more questions ... having not built anything this size i might be overthinking.

The AllMovingTailplane, bowden cable or a carbon pushrod recommended, or something else.

Various ‘wire’ components such as AMT rod and actuating pin ... piano wire or stainless steel wire.
I realise thats a loaded question as in ‘steel’ or ‘steel’ but im thinking of the stuff you get in the average model shop these days. Piano wire always seems to be quite soft these days.

If ChrisW is around, coukd you explain the ‘dry hinges’ and masking tape on the ailerons please.

Any help appreciated.

Cheers

Mike
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chris williams
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Re: Slingsby Petrel 3.4m - ChrisWilliams - PreBuildQuestions

Post by chris williams »

A 5mm carbon tube will suffice for the pushrod, with 3mm threaded rod at each end and 3mm metal clevises. If the tube should bend in the middle under tension, support with balsa cross-brace. (Bowden cable for the elevator? Never! (Don't ask))

Piano wire is fine for these purposes

The ailerons are held in place with the hinges un-glued. The insulating tape retains them and also seals the gap. The gap underneath is sealed with a strip of draughting Mylar' or similar, and double sided tape... This way, the ailerons can be easily removed should a wing repair become necessary.

Don't know if I've asked this before: have I sent you all the Petrel-related stuff, build pics etc...?
Mick666
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Joined: 03 May 2019, 22:30
Location: UK

Re: Slingsby Petrel 3.4m - ChrisWilliams - PreBuildQuestions

Post by Mick666 »

Hi Chris

you have sent them thanks. I've been building FF, CL and RC for years but like I say, this is a big one for me.

So I'd rather be asking dumb questions on a forum than explaining away a half buried model on the hills to my chums :D

I get what you mean about the hinges ... bit like a 'blenderm' or 'live' hinge all the way along.

Standby for the next dumb question coming to a forum near you soon.

Cheers

Mike
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