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Ron Collins F86 - foam/carbon build


Mike Chantler
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Thanks guys ?

And yes - kevlar is for live hinge, surface has 'dimples' ?. Dimples could either be due to the XPS texture, or more likely (I think) due to excess resin. On one surface I used peelply to remove as much resin as I could (at most 1-2g) - this is flatter I think, but has a couple of dry spots where the glass/XPS was still wetted out, but there was not quite enough resin to form the 'gloss' surface against mylar (75 micron laminating pouch).  I only used the peelply on one surface as my resin started to go off and I panicked a bit to get them under weight (needed this as one tailplane had a bit of a curve ). I could of experimented with some stiff(.4mm) mylar I have - but only thought of this just now(!) and it may well have needed to be bagged, which seems a bit overkill and time consuming.

 

I've dabbled before with using finishing resin as a second coat on glass and not had good results, so my feeling is that a deep fill primer of some sort would work much better? Guess it depends on the dimples ?

Edited by Mike Chantler
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  • 2 weeks later...

Did a lot of head scratching, coffee and diversio n activities, while avoiding decisions on how to mount tailplane.

 

Eventually chickened out of the linkages when I discovered that the tailplane (10% NACA 0015) was thick enough to take small servos (am doing simpler, early conventional tailplane). And decided that the shells from the hot wiring would make good housings and reference  for the tailplane itself. So cut holes and then decided to look at real pictures of F86 as had no real idea of how they were mounted. Discovered they were much higher than on Ron's plan so added extra foam to boost them up.

 

IMG_20210602_230929.jpg

Tailplane with shells

 

 

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Tailplane cored for servo runs

 

 

IMG_20210607_222013.jpg

Raised and trimmed shells in place.

Edited by Mike Chantler
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next problem was getting  the tail vaguely F86 shape - I had not realised that it was more complicated than I had though - so decided to get the profile right round the tailplane mounting and leave the rest to later in the build (yup - there is very little advance planning going on here, and I'm beginning to think that I should of just bought the mass build plan (sorry Ron ? ).

 

IMG_20210611_101407.jpg

 

Position of bellcrank below shows original position of tailplane

IMG_20210611_102639.jpg

 

Having raised the tailplane quite a bit I've now decided its about 5mm to high(!) but am just going to live with it as the whole model is a bit of an experiment for me.

Edited by Mike Chantler
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  • 4 weeks later...

Have done a bit more filling and shaping just to get the feel of these materials. And then decided that I'd have to know more about the canopy before going further - the bit I was dreading as my previous attempts at vacuum forming a few years ago were demoralising and I totally lost patience. Especially frustrating when it looks so simple and folk get such nice results. 

 

But happened across this recent nice vid: here

 

So before trying a vacuum set up I thought I'd try the coke bottle and heat gun trick.

Edited by Mike Chantler
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Produced pretty rough MDF plug and tried it - wow it worked ??

IMG_20210711_181902.jpg

2L Coke bottle not long enough so will do in two parts:

IMG_20210713_120848.jpg

 

IMG_20210712_171402.jpg

 

Some imperfections (e.g. front wedge too wide so bottom front did form properly and not as smooth as I would like)   - But, am mega pleased with first attempts - MUCH easier than I expected ? ? ? 

Edited by Mike Chantler
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  • 2 weeks later...

So got really frustrated myself when applying and reapplying light filler to fus. grrrrrrrrrrr..........

Was far too impatient and sanded before 24hrs on tool cluttered table which meant sandpaper quickly clogged and its (and tools) were adding more more dings each time than I was removing ??

 

Could feel the vicious spiral of disaster coming on ... more dings and mistakes, more frustration, more impatience, more dings ... you know what I mean 

 

So decided new tack of a) covering in with 25g glass and b) reading the MB blogs as recommended by Martin (note I only read instructions when things start to go wrong lol).

 

 

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So discovered Freddie B's sauce on Phil and McG 6969 threads 

 

Also checked out some of Freddie B's build notes as recommended by Chris - so thanks guys  - these were a bit of a life saver. Both for the 'sauce' and Freddie's comment somewhere not to buy cheap sandpaper. So I went to tool station and bought the most expensive 'sandpaper' I could see and did a sauce mix ?

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Discovered sanding 'mesh' - this is absolutely BRILLIANT as it does not block at all. Fantastic stuff.

 IMG_20210721_160323.thumb.jpg.cc28f46d375075c7476273095f434f02.jpg

 

The Prodec stuff is quite course (120 grit) but worked well. However, the Abranet 180 grit was even better - seems to remove material faster than the Prodec but finer finish ?

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Glad if Fred's Sauce could stop your "vicious spiral of disaster", Mike...  ?

 

Don't worry about those talcum 'grits', they sand away like butter.

 

Please be patient this time and let the Sauce dry for at least 24 hours before sanding.

 

Cheers & good luck

Chris

 

Oops > ... a bit late, I guess...

Edited by McG 6969
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