SHORT BROS NIMBUS SCALE 1:3.5

Let us all watch your new project progress.
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Cliff Evans
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Cliff Evans » 07 Dec 2018, 01:11

Very impressive Mr Smits. Coming on a treat.

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 07 Dec 2018, 03:10

There were several option in my mind how to plank the top of the wing stubs with those compound curves. Lawrie Prest suggested one of my options and I decided to go with that one.
1/8" square spruce stringers were added as shown on attached pictures. they run from the Main fuse former to trailing edge. To the front 4 mm balsa sheet was used due to the strong curve .
A 6 mm balsa support was added 20 mm from the outer rib, this area is in line with the wing surface until the fairing radius starts
20 mm wide 0.4 mm plywood strips are now added as shown with a cross grain.
I use Quick Set PVA for this job. One can remove the clamps after 10 minutes so it does not have to be that time consuming I do however wait 30 minutes
The clamp holds the ply down from rib to the 6 mm balsa support to make sure this area is flat following the wing surface
every strip needs to be test fitted to make sure it is close to the adjacent strip but a little gap is not so much of a problem
The strips follow the natural curve and only a pin here and there is required to hold things in place.
due to the strong curve at the front The strisp will be 12-16 mm wide
When the total stub is covered a second 0.4 mm ply layer will be fitted.
This are either strips with the same orientation but half a strip offset or say 6 mm wide strips perpendicular running the full length of the wing stub.
Keep you posted.
Attachments
F053.jpg
rear stringers fitted
F054.jpg
front stringer 4 mm balsa sheet
F055.jpg
finished stringers
F056.jpg
first 5 strips in place
F057.jpg

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Peter Balcombe
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Peter Balcombe » 07 Dec 2018, 08:05

Very nice indeed Jilles.
Keep up the good work.
Peter

john greenfield
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by john greenfield » 07 Dec 2018, 08:33

Jilles

I reckon you could put those strips on using the PVA and hot iron method. Once set up with the strips cut and the parts coated with PVA you could progress much quicker and not need the clamps.

Just a thought.

Regards

AEB
AEB = Aeronautical Energiser Bunny (with thanks to CW)

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 08 Dec 2018, 05:27

the Iron on method is a bit tricky on a hollow surface unless you have a small iron. I once tried a little iron that is used for attaching film but the one I have does not seem to be hot enough or because of the small size looses the heat to fast.
I prefer to put down a strip permanently and than test fit the next strip. It does not go must slower than the Iron on option because you do not have to wait an hour for the PVA to dry before starting the ironing process.
There is no date for this model to be finished, so building time is not an issue. Also I have three vintage glider designs in the pipeline, two for Cliff so time has to be divided between various projects.

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 10 Dec 2018, 09:51

The RH wing stub is now completely planked. the first layer of strip went on fine, the tail end has larger pieces of ply because it is only bend in one direction. The first layer was sanded smooth. After sanding the exposed layers of the ply show that the first layer of strip were not 100% inline with each other. This is not a problem. For the second layer a 12 mm wide 0,4 mm ply strip was added over the full length on the top and a approximate 20 mm wide strip from the edge of the root rib to the start of the fairing radius. This outer strip was widened at the front and covers the balsa leading edge all around to join the wing stub bottom planking, see picture F061.
To finish the second ply layer vertical strip were added again half a strip offset from the bottom strips. With the horizontal top & bottom strip there are two edges to hold the vertical strips in place. With the correct length of the vertical strips they follow the bottom contour with a little tension. No clamping required to hold them in place for the glue to set.
Pictures F063-65 show the second layer lightly sanded. later epoxy mixed with sanding filler will be applied to fill little gaps between strips
The last bit at the front of the wing stub will be solid balsa sanded in shape as required.
This will be the last post on this subject for the year. Planking the LH wing stub will be done the same way so no use to show the same thing again
Christmas is coming up then a visit to offspring and their offspring in New Zealand. The built will resume the end of January.
A merry Christmas and happy new year to all SSUK followers
Jiles Smits
Attachments
F058.jpg
firs layer of strips sanded
F059.jpg
F060.jpg
the tail with larger ply slabs
F061.jpg
F062.jpg
ply strips top & bottom
F063.jpg
second layer of ply completed
F064.jpg
F065.jpg
second layer sanded

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Cliff Evans
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Cliff Evans » 10 Dec 2018, 10:33

Merry Xmas Jilles, hope you have a great festive season.

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Barry_Cole
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Barry_Cole » 10 Dec 2018, 12:06

Brilliant Jilles. Merry Christmas and a Happy New Year.

:D :D :D :D

BC

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