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 » 04 Nov 2018, 08:19

I think when I first asked you to look at this aircraft, I was not that keen on it myself but, the more I look at it and the more you build, it is becoming more and more apealing! Thanks Jilles.

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 04 Nov 2018, 09:56

I hope to get a weight of approximate 12 kg in total. But with the short nose there will be a substantial piece of lead required in the nose, so who knows.
No to afraid of it. The Zephyrus of Vince is 15 kg at the same scale. We have a 6m Ka8 flying (Phoenix with substantial mods to keep it together in flight) in our scale group at 18 kg. Despite this it does not come down in a hurry. All to do with wing area of course.

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 08 Nov 2018, 09:51

More Ply planking done to the fuse. closing in on the nose area. Compound curves so a bit more clamping force is required but so far so good
The planking is at the moment only at the top only with the main side stringer as guide. Except on top of the wing stub. The fairing radius is very large and reached nearly to the main stringer, In that area the ply was extended a bit lower When all top planking is done I can remove the fuse from the base and turn over for the bottom planking.
A 5 mm balsa support base is added between formers and stringers of the nose top. To much of a compound curve ply +/-8 mm wide tapered strips will be fitted here
Attachments
F028.jpg
F029.jpg

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 18 Nov 2018, 01:19

Progress again. Need to divide time for building the Nimbus and vintage glider designs for others.
The horizontal stab was planked top & bottom with 0.4 mm ply using the iron on method.
Test fitted the stab to the fuse and a frame was made for a top fairing. This is to builders preferences, no detail on the drawings for this. 3M magic tap to the top of the stab prevents the fairing frame to be glued to the stab. the fairing or cover has a 1/8" dowel at the front and a servo screw will retain the rear end onto the stab.
I will use a single plug and socket for both elevator servos. One channel each. This is as mentioned earlier a personal choice. other ways could be used.
I do like one plug, When the wires are soldered in the correct way in the first place no chance one have a mix up at the field or reverse the servo plugs.
The fairing was also planked with 0.4mm ply wood and the shape extended to the bottom of the fin structure with balsa. The fin also has 0.4 mm ply planking
filler and sanding will finish this area later .
I made some temporary stands so I can turn over the fuse. The front stand is located over the main former assembly, the rear is held in place buy two M4 socket head bolts , the same that will retain the stab in future
The fuse is now turned over and the building support stands on the bottom of some formers can be removed. An other planking session is now coming up after some work on the interior
Attachments
F030.jpg
planked stab test fit
F031.jpg
fairing frame
F032.jpg
check wiring plug
F033.jpg
fairing complete
F034.jpg
brackets fabricated
F035.jpg
F036.jpg
F037.jpg
fuse turned over
F038.jpg
ready to remove former stands

Lawrie P
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Lawrie P » 18 Nov 2018, 06:08

Looking good Jilles.
Have to agree with Cliffs comments at top of the page.

Lawrie.

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VinceC
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by VinceC » 18 Nov 2018, 08:42

Nice to see the fuselage coming together so well. How are you feeling now about the unusual geometrics of the wing stub and wing attachment?

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 18 Nov 2018, 22:28

The wing stubs on the fuselage will be interesting. Now I have the fuse together and see the size of it all there are have several ideas. Depending on the way I will get it together there may be some parts added to the cutting list for potential future builders to make it a bit easier. First the bottom planking needs to be added to the full length of the fuse then the stubs will be next.

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 01 Dec 2018, 04:58

Some progress again, before planking the bottom of the fuse the two elevator servo wires were fitted as well as the pull-pull cables for the rudder
It would be nearly impossible to get these in place with planking fitted. Because of the long length of the pull-pull cables I added a support half way
(picture F040). the space between the first two fuse formers packed at the bottom with balsa to support ply strip planking. Due to high tension the front ply parts were fitted with cable ties to keep the parts in place during curing of the glue. The Iron on way would not work due to the high tension in the ply.
Additional support was added in bottom wing stub to support future ply planking in the form of balsa strips
The leading edge of the wing stub formed with solid balsa, this does not include future fairing radius to fuse surface planking.
Attachments
F039.jpg
servo wires an p-p cables fitted
F040.jpg
p-p cable support half way
F041.jpg
balsa support for ply strip planking
F042.jpg
clamping sample of front ply sections
F043.jpg
front planking completed
F044.jpg
support formers in wing stub bottom
F045.jpg
L/E to wing stub

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VinceC
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by VinceC » 01 Dec 2018, 09:50

That is quite some model, quite an engineering task, but the results are going to be good

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 07 Dec 2018, 00:52

Planking of the wing stubs has started. Bottom first because this side is relatively easy. It does not have the severe compound curves as the top does. attached pictures show how ply sheets were added and in what order.
The tail structure that will support the skid was prepared for planking, M3 Tee nuts or blind nuts depending where you come from are put in place to fit the tail skid later. My plan is to use nylon screws and hope they will shear if I manage a ground loop and not cracking the tail section.
Attachments
F046.jpg
rear ply sections in place
F047.jpg
rear view stub
F048.jpg
center section with wheel opening in one piece
F050.jpg
bottom ply planking complete
F051.jpg
tail skid support structure ready for planking
F052.jpg
M3 nuts in place

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