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2017 Mass Build Chat Thread


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Posted by Tim Ballinger on 04/02/2017 15:07:29:

Hi all, I'm just returning to the hobby after a 40 year gap and belatedly have started following your skywriter builds. Finding them very interesting so pleas keep on blogging. Having rescued some of my original models from the loft I done some refurb and have been getting some of my flying skills back up to scratch over the winter. I am itching to start building again and was trying to choose between a slec funfly and the skywriter. Since I have always fancied a biplane the skywriter has won the day. Not so much joining the mass build as gleaning everything I can from what you are all doing. So having made the decision I guess I'd better get the plans/parts on order. Tim

Welcome to the merry band of Skywriter builders Tim... Happy building

Peter

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Welkom Tim. I you read the "Gentle Curves" thread feel free to ask any questions about what/why I do. I am only a few planes ahead of you (in building), and I have had much help from others through these build threads.

And do start your own build thread!. You may get some "unasked for" advice that may be very valuable in that other see mistakes on the pictures you may not yet have discovered.

Good luck and happy hours building!

Lucas

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Disaster has struck (not unexpectedly). Pulled the tail end of the fuselage together, clamped it up and glued it with white wood glue. Removed clamps after about 24 hours and it remained solid for about 48 hours when the two sides decided to part company (close-up in second photo). I felt that when drawing the two sides together there was a terrific amount of strain on them so, as said, it was not unexpected. You will see that the balsa has given way and not the glue line. Unless anyone can suggest anything better I can only think that I will have to glue and clamp it up again and add some triangular section reinforcement to the insides plus the tail support. I think I should have done what, I believe, Lucas suggested and cut some lightening holes in the fuselage sides and it would have made them more pliable at the tail end but too late now.

Derek.

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p1010660.jpg

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Use a crossgrain piece for the triangular bit next time and perhaps not pull in quite as far?

 

It would probably have been easier to pull the tail in before the top stringers were fitted . If it had seemed too much strain then it would have been possible to slim the last former a bit. A bit late now so you may have to accept that the tail will be little wider than planned.

 

Edited By kc on 06/02/2017 17:48:56

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Thanks, guys. All the parts were as per the drawings and supplied in the laser cut kit and, so far as I can recall, I was following Lindsey's build log, so I could not see that I was going wrong in the build sequence but I have not seen any other comments about the difficulty of drawing the fuselage sides together. It would be interesting to hear from builders who have got past this stage had any problems and whether others approaching it will, in view of my problems, do anything differently.

Derek.

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The longerons are probably the culprit here. I do not have them but felt I had to use quite a bit of force to get the side together after F9.

I suggest you take out the tailplane support and clean up the old glue lines, then cut the longerons away away after F9. In addition taper the outside doublers down to 0mm (yes, until the glue line at the tail post (see the drawing). You can also taper the outside stringers from F9 backwards.

That should make things much more plyable. If you still feel too much force is needed do not glue and hope for the best, but clamp (and/or tape) the side together as far as they willl go and wet the outside, eithter with a steaming iron or with ammonia. Leave for a day and pull in a bit further. When the easily go together glue them and when dry glue in tailplane support and tailwheel support. Only then take off the tape that held the sides together.

Two steps forward, one step back. And sometimes vice versa. If you continue you will get there in the end.

Lucas

Edited By Lucas Hofman on 07/02/2017 07:05:47

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Posted by Derek Bradley on 06/02/2017 19:14:30:

..., I was following Lindsey's build log, so I could not see that I was going wrong in the build sequence but I have not seen any other comments about the difficulty of drawing the fuselage sides together....

Derek.

I have seen a mention of quite a bit of force needed to get the fuselage sides together, but do not remember where. You did nothing wrong Derek, this is a consequence of the design: 6mm longeron, 3 mm sides and 3 mm stringers make a packet of 12 mm laminated balsa. That is never going to bend easily.

Lucas

Edited By Lucas Hofman on 07/02/2017 07:16:58

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Take a gin-and-tonic, a good beer or wine, whatever you prefer and start cleaning up. when all remains are out and the surfaces clean again it does not look so bad (this is from experience).

By the way you now have experienced the valueof these threads. As soon as you have published a problems you have 2-3 people pointing you in the right direction (or at least in what they think is the right direction

Lucas

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I found the sides very stiff to pull together with just the 1/4 sq longerons glued to the fuselage sides i.e without the 1/8 stringers on, so there is a bit of pressure there.

If you're having problems then I can't recommend ammonia enough. Balsa soaked in ammonia becomes very bendy and pliable but has no detrimental effect on strength or glueing when dry. It just makes the worksop smell bad for a bit!

Just soak in ammonia, bend and clamp in position and leave it to dry. The balsa will conform to the shape you want and will pretty much stay that shape when you remove the clamps to apply glue and then clam in it's final position. If you don't have ammonia then you can use white vinegar or just hot water but it really isn't as effective or as quick to work.

Once you've discovered ammonia you'll be using it all the time!

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