SHORT BROS NIMBUS SCALE 1:3.5

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

Post by Jilles » 08 Mar 2019, 05:30

O yes we just have a record of 45 days in a row of temperatures between 30-38 degrees C. This also slows down the building time of the Nimbus

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VinceC
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by VinceC » 08 Mar 2019, 08:45

Nice seeing the project coming together. This is going to be something different.

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 11 Apr 2019, 04:06

Not many new things to report. the R.H wing built is in progress along the same lines as shown earlier in this thread for the L.H wing
Attached pictures show the second wing. The Balsa leading edge has been sanded into shape. I did this outside to prevent the workshop becoming a dust bowl. The wing is now back on the building board and ready for the top plywood planking.
Temperatures are now in the mid 20's so much more pleasant to be in the workshop and outside
Attachments
W60.jpg
W61.jpg

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 15 Jun 2019, 08:02

Hi all. it has been a while. The second wing is now done. the tail bits are built and test fitted. A start was made on the canopy frame. I received the canopy from the UK thanks to the help of Cliff. I decided to make the hinges myself from 3 mm alu strip and angle. A 1.5mm (1/16") hole was drilled in the hinge blades. 1/16" spring wire is used as hinge pins. The fuselage part of the hinges are epoxied in 3 mm ply pockets inside the fuse.
The fuse is curved in that area so the hinges are at an angle with the fuse surface but inline with each other. A 2 mm holes was drilled through the canopy cockpit base and hinges and a 2 mm pin fitted to lock it all in place
the canopy hinge parts are epoxied to the frame and locked with a servo screw for extra security. A latch of 3 mm alu strip was fitted to the other side to keep the canopy locked with a standard brass spring loaded canopy lock. The original glider canopy had a large sliding window at that side. The model will have the same for access to the lock bar. To restrict the opening angle of the canopy a 1/16" piano wire at the rear of the canopy will take care of this. A string or leather strip could do this but from experience I know they will get stuck between all type of parts in that area.
Attachments
F079.jpg
tail bits are made and test fitted
F080.jpg
canopy hinges from 3 mm alu strip
F081.jpg
hinges in fuse pockets and pinned
F082.jpg
latch for the canopy lock
F083.jpg
canopy frame in place and hinged
F084.jpg
canopy lock in place
F085.jpg
a piano wire restrict opening angle of canopy
F087.jpg
detail hinges inside fuse pinned and screwed

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 02 Jul 2019, 02:47

Some progress again after a brief stop to visit the grand children.
Subject this time is the skid assembly. This was made from 2 sheets of 3 mm aircraft ply laminated together in the correct contour.
Because the main wheel is located well behind the C.O.G the model will be resting on the skid. To make the skid surface more wear proof a layer of 0.8 mm alu sheet was epoxied to the underside. The skid will be screwed only to blocks in the fuselage so possible future damaged to the skid can be fixed easily. The skid assembly comes in at 95 grams, this will help to get the COG in place with the relative short nose section
There is not much prototype info on the skid details. I did presume it was cushioned with rubber blocks and the gap covered with fabric/canvas as was the standard in those days. The model skid is fixed and 0.8 mm plywood sides to close the gap are added. For those that might not familiar with getting edges of panels of any kind curved in the correct shape I take this opportunity to show how I manage that my way.
Cute the edge of the panel roughly into shape and then locate in place. With a flat washer the proper contour is drawn by rolling the washer over the contact surface and hold a pencil to the washers internal hole. Cut the panel along this line and you have a perfect match. A M6 washer was used. One can use bigger washers but that will result in more waste of plywood/balsa
Attached pictures will explain how this works
In this case one side was fabricated and then used as template for the other side. The plan is to paint these panels green to simulate canvas. If there is somebody that may know what the color was on the real glider please let me know. The plan is to paint the model as shown on pictures I have from 1971 and the stored wreck of 2018. White with a red/orange fuse bottom and wing tips. A black trim line between the white and red.
Attachments
F089.jpg
skid attachment blocks to extended fuse formers
F090.jpg
Skid assembly with alu sheet layer
F091.jpg
skid side view
F092.jpg
test fit of skid
F093.jpg
rolling washer with pencil to get a contour
F094.jpg
rolling over full length
F095.jpg
result after trimming side along pencil line
F096.jpg
side panel bottom line trimmed to suit skid

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 09 Jul 2019, 04:31

The canopy frame was completed and test fitted on the fuse. the inside was primed and painted. To keep the frame level and true a temporary frame was made to keep the frame in check in a vertical attitude. This vertical attitude made adding clamps to keep the canopy in place on the frame mush easier
masking tape was used as well on those locations were a clamp did not want to stay in place due to curved edges of canopy and frame. After 24 hours clamps and tape removed and edges trimmed.
Canopy assembly fits in place without the need for adjustments
A rectangular hole was cut in the side to reach the canopy latch. This is in scale location and a sliding window will be added later.
Attachments
F097.jpg
canopy frame inside painted
F098.jpg
temporary frame for fitting canopy
F099.jpg
canopy frame clampemd in place
F100.jpg
canopy glued in place
F101.jpg
canopy edges trimmed and test fitted

Jilles
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 09 Jul 2019, 04:55

Today all parts were assembled for the first time. all things went together without a problem. Not one of my smaller projects
parts were weighted and required balance weight calculated. Estimated flying weight to be under 12 kg (25 lbs)
wing loading is then 68 gr/dm2 (23 oz/ft2). for this model seize a good outcome. Final figures will be known when all painting is completed and electronic equipment installed.
Now a sanding and finishing job is ahead of me. The fabric used will be Ikarex. A polyester fabric that does not need dope to close, will shrink as standard film but need the application of heat sensitive glue like Sig Stix-it or balsa block. Ikarex is also very suitable for painting
Attachments
F102.jpg
F103.jpg
F104.jpg
F105.jpg
F106.jpg

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Cliff Evans
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Cliff Evans » 09 Jul 2019, 06:57

Very nice Jilles.

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VinceC
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by VinceC » 09 Jul 2019, 09:01

Genius. That is one nice glider

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Peter Balcombe
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Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Peter Balcombe » 09 Jul 2019, 10:42

Very nice Jilles :)

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