Rotor Pitcheron Scratch Build UK - RC Groups
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Oct 26, 2017, 08:41 AM
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Build Log

Rotor Pitcheron Scratch Build UK


I have wanted a pitcheron ever since Jay Decker (Sled Driver) posted his TWF Build Orgy thread, and wanted a Rotor since he made Ken Stuhr’s plans available on a website I can’t remember or find (please post the link if you know it).

This project was started in 2013 but had to be shelved. I am now ready to continue the project so I will publish the work done so far and endeavour to be consistent with future progress.

This project is definitely budget driven, so the fuselage was built out of common builder’s ply and pine triangle. The wings (my first attempt at bagging with Mylar carriers) will be laminated with glass.

I decided to build the model in triplicate to reuse any templates, Mylars, etc. that would otherwise be discarded after a scratch build. Also if I bury one airframe I will be less upset than if I buried the only airframe.

Sorry for the grubby photos to date. Future ones will be much better.
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Oct 26, 2017, 08:47 AM
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Squaring Up


The pine triangles were not precisely right-angled in section and it was impossible to get both fuselage sides to align perfectly, so I marked the exposed triangle with felt tip pen and trimmed the fuselages square with the vertical sanding belt.
Oct 26, 2017, 08:50 AM
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Ward Hagaman's Avatar
Nice fuselage jig!

How thick is the ply for the fuse sides?
Oct 26, 2017, 08:58 AM
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Detail Shaping


After coarse shaping, “shoe shining” the fuselage with 60 grit got the section curvature consistent. This technique does to curved sections what the sanding bar does to flat sections: it removes all relative high spots. Works great on block wing tips.
Oct 26, 2017, 09:04 AM
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Ward Hagaman's Avatar
Beautiful work!

What kind of weights are you getting on the fuses?
Oct 26, 2017, 09:05 AM
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The Facilitator – My new vacuum pump


Yay! Decent pictures from now on!

One reason this project got shelved back in 2013 is because I didn’t have an adequate vacuum pump. I have bagged veneered wings with an old fridge compressor but I wanted a more professional setup for composites.

I recently built the vacuum pump below using Joe Woodworker’s free guide for reference (https://www.joewoodworker.com/docs/ProjectEVS.pdf). My machine looks nothing like Joe’s but follows his system and concept to the letter, complete with pump start-up relief and use of a relay to increase the life of the vacuum switch.

The vacuum reservoirs are aluminium cycling/rambling bottles of one litre and half litre (the white one) capacities. The machine’s footprint is 30cm x 25cm (12” x 10”).

I got the Gast pump on eBay for £25 in 2008. It was grimy for it had seen considerable industrial use and had an electrical inspection label on it dating to 1995! It is now squeaky clean thanks to some TLC with baby wipes and a popsicle stick to push the wipes into tight spaces. You won’t believe how good baby wipes are at removing grime. The pump’s gasket and diaphragm had long since perished so I made new ones. The pump now works as intended.
Brassware, tubing, gauge, etc. were sourced at Easy Composites (easycomposites.co.uk). The remaining components were got from eBay and other sources. Total investment so far is just over £250, but this tool should last me for life.

Dodgy wiring will be isolated soon, I promise.
Last edited by Kenneth Paine; Oct 26, 2017 at 09:26 AM. Reason: Spelling
Oct 26, 2017, 09:10 AM
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This is where we are


This is the current state of affairs. There is an ulterior motive as to why I have resurrected this project now: I am self-employed and work has stalled for the time being. Whilst I am not superstitious, Murphy’s Law is as certain as death and taxes, so now that I am committed to this thread the work will flood in preventing me from making any progress.
Last edited by Kenneth Paine; Oct 26, 2017 at 10:12 AM.
Oct 26, 2017, 09:12 AM
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Quote:
Originally Posted by Ward Hagaman
Beautiful work!

What kind of weights are you getting on the fuses?
Ward,

Thank you very much.

I have just weighed the fuselages and they are:
  • 254g (9.0 oz)
  • 287g (10.1 oz)
  • 298g (10.5 oz)
Oct 26, 2017, 09:16 AM
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Poll


I have the following cloth for laminating onto the cores:
  • 220 g/m^2 (6.5 oz/y^2) unidirectional
  • 24 g/m^2 (0.7 oz/y^2) plain weave
  • 81 g/m^2 (2.4 oz/y^2) plain weave

What should I use? 220g and 81g or 220g and 24g? Is one layer of uni enough?

Bear in mind that I have nice grassy slope tops locally and don’t need rock cracking toughness. I just need enough to avoid in-flight failure at, say, 100mph.
Oct 26, 2017, 09:21 AM
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Quote:
Originally Posted by Ward Hagaman
Nice fuselage jig!

How thick is the ply for the fuse sides?
Thanks Ward, I missed this question.

The ply is 3mm (1/8") and the pine triangle is 12mm (1/2"). Pretty much as per the plan so far.
Oct 26, 2017, 10:16 AM
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I would go 6.5 uni and a 2.4 on the bias over the Mylar first. Good and solid and not real heavy
Wrap the leading edges with Kevlar and carbon if you have it.
Very nice work so far
Cheers


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