SHORT BROS NIMBUS SCALE 1:3.5

Let us all watch your new project progress.
User avatar
VinceC
Site Admin
Posts: 643
Joined: 22 Feb 2015, 11:45
Contact:

Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by VinceC » 27 Jan 2019, 10:19

That looks an interesting transition which must have been a nightmare even for the full size builders. Nicely done Jilles

Jilles
Posts: 155
Joined: 22 Mar 2015, 10:27
Location: Australia
Contact:

Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 28 Jan 2019, 05:46

The wings are the next items I want to built. The spar sections are 1/2"x1/4" and need to be bend because we have a gull wing here
the spars were bend by steaming. It takes a while but not impossible. The bending template included in the NC parts laser kit is very helpful to get the result required.
the spar webbing was assembled and the bottom spar glued to the webbing. The False L/E was assembled as well. both spar webbing and L/E are assembled on a flat surface with a straight edge against the building tabs of the outer sections to keep things in-line. A building base has been erected from particle board with the correct gull angle. This base will be used for both l/h and r/h wing.
I have to go to the printer to get the wing drawing printed, they will be used on the base board

Coming back on the transition of the wing stubs fronts. The original factory drawing was provided to me by Vince .He must have a very extensive library of many gliders.
The drawing is not 100% clear on the front transition and pictures of the full scale or what is left of it show the prototype had some variation in that area compared to the factory drawing. Suppose the builders used their imagination to get a practical result.

As for my workshop, I am proud of it and know roughly were everything is

F072.jpg
F073.jpg
F074.jpg
F075.jpg
F076.jpg
F077.jpg
F078.jpg

Geoff Pearce
Posts: 404
Joined: 18 Mar 2015, 09:11
Location: SN11 9EE

Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Geoff Pearce » 28 Jan 2019, 12:00

That looks awesome , I envy the space you have

Jilles
Posts: 155
Joined: 22 Mar 2015, 10:27
Location: Australia
Contact:

Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 03 Feb 2019, 05:21

A building base was built to accommodate the building of the gull wings. I bought 16 mm thick craft wood panels from the local Hardware shop. They were seconds having damaged edges but otherwise straight but cheap. The surface of the building base was checked that is was straight and level The drawing set has two wing drawings, the inner and outer panel. They show the true view of the panels respectively. On these drawings a cut line were the joint of the two base plates is shown. When you go to the printer ask him to print both drawings mirror reverse as well for the R.H. wing, The building base is good for both the L.h. and r.h wing. A note on long paper drawing sheets they shrink or expand subject to moisture and temperature. In my part of the world it is at the moment between 30-35 degrees C and humid, as a result the outer panel drawing is longer ( 3mm) than it should. This is not an issue, the ply webbing of the spar has notches dictation the location of the ribs and other parts.The drawing on the board is only there to make sure the spar is straight and showing the parts that need to be fitted.
After the drawing is secured to the building base the spar is fitted kept in place by aluminium angle and screws. ribs are then test fitted and glued in position. the false L/E is also held in position by small wooden blocks. The spar webbing, false L/E and most ribs have tabs that rest on the building base. This makes sure all is at the correct location
Today the top spar was fitted. requiring lots of pegs to hold the ply webbing to the top spar member
Not mentioned before is that I have epoxied 10 x 0.5 mm carbon strip to the inside if the top & bottom spar section for additional strength ( see pictures). they come a meter long and in this case go past the gull radius. The remainder of the outer spar (1.4m) does not have carbon strips

W01.jpg
W02.jpg
W03.jpg
W04.jpg
W06.jpg
W07.jpg
W08.jpg
W09.jpg

User avatar
B Sharp
Posts: 597
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by B Sharp » 03 Feb 2019, 09:20

That is a seriously impressive piece of work Jilles.
Brian.

User avatar
terry white
Posts: 501
Joined: 18 Mar 2015, 21:08
Location: wareham,dorset.england

Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by terry white » 03 Feb 2019, 15:04

Excellent work as always Jilles and a super build tread too. Well done.

Jilles
Posts: 155
Joined: 22 Mar 2015, 10:27
Location: Australia
Contact:

Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 12 Feb 2019, 03:55

Spar front webbing at wing joiner sleeve and near gull radius added. Hinges and horn for air brakes fabricated. The hinges are fabricated from scratch from square brass tubing, The prototype has the brake blades behind the main spar but is hinged at the front to the spar. The hinge main body is a 5/32"x0.014 square tube the hinge bit a 1/8"x0.014 square tube. all brass from K&S engineering. The reason to go for square tube is that it gives a better contact area for hard soldering the parts together. The hinge pins are 3/32" brass round bar. It makes no difference if the round pin hinges in a round or square tube. Because the hinges are running over the main spar the spare is actually sunken below the rib surface top & bottom otherwise one has to make a slot in the main spar, what I did nor wanted for strength reasons. The brake fitted in to the wing, checked movement and added ply surface
note in picture W11 that the sunken main spar has the advantage that the shoulder spars can run over the main spar resulting in a proper shear joint

W10.jpg
ply webbing to front of spar
W11.jpg
ply webbing at gull radius
W13.jpg
brake hinges and horn
W14.jpg
hinges and horn epoxied in place
W15.jpg
servo screws added from underneath
W16.jpg
srews sanded flat and brake fitted in wing
W17.jpg
checked movement
W18.jpg
ply surface added to brake

Jilles
Posts: 155
Joined: 22 Mar 2015, 10:27
Location: Australia
Contact:

Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 12 Feb 2019, 04:17

With the brake in place the balsa leading edge was fitted and sanded over the full wing length. on top of the main spar balsa was fitted and sanded flush with the rib surface. 6 mm balsa sheets added between the ribs in the gull radius for future ply support.
My drawings specified 0.4mm ply on the D-box. Due to the larger area to cover I decided to go with 0.6 mm up to and including the gull radius.
Ply sections were prepared and ironed on with PVA. The ply section will be between 400 to 450 mm long. Longer sections are harder to control
When applying the PVA masking tape is used so only glue is added where required. One could fit the top ply cover over the full wing length in one day was it not for the fact that we have here days of 35-38 degrees C. making it 40+ in my workshop. so only early morning working sessions are possible.
Note the leading edge was sanded only 5-10 degrees past the vertical at the bottom. I do not want to take the wing from the base board until all the top D-box ply is in place.
How things are kept in place for the bottom ply will be revealed later

W20.jpg
air brake ready
W21.jpg
6mm balsa sheest between ribs at gull radius
W22.jpg
l/e sanded , balsa to top of spar
W23.jpg
cutting ply d-box sheeting
W24.jpg
second sheet prepared glue area taped.
W25.jpg
PVA added waiting for an hour now
W26.jpg
iron on the wet ply
W27.jpg
second sheet in place

Jilles
Posts: 155
Joined: 22 Mar 2015, 10:27
Location: Australia
Contact:

Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by Jilles » 14 Feb 2019, 09:43

To cover the D-Box over the gull radius I did the following. At radius area in the D-Box 6 mm balsa was fitted between the ribs and sand to the required contour. A ply section was cut to size and three grooves were cut running approximately from halfway to the front. The slots start with a zero width ( knife cut) to 1 mm wide at the front. The ply was fitted with the PVA iron- on method and worked well. Because of the compound curve at the front there would be to much ply material, the three wedge type slots took care of this. This way would never be possible on a full scale because it would weaken the wing structure, but on this model with 6 mm balsa backing it is not an issue. There are probably other ways of doing this but for me it worked well .Because it will be a painted model the slots will be invisible. After this two more play sections were added, two more and the top of the D-Box is fully planked and I can start thinking of the bottom.
20190214_113933.jpg
Ply section cut and slotted
20190214_113940.jpg
area is filled in with 6 mm balsa and radius sanded
20190214_192306.jpg
final result
20190214_192313.jpg
two more ply section added today
20190214_192320.jpg

User avatar
VinceC
Site Admin
Posts: 643
Joined: 22 Feb 2015, 11:45
Contact:

Re: SHORT BROS NIMBUS SCALE 1:3.5

Post by VinceC » 14 Feb 2019, 10:20

Good work Jilles and coming along well. On my See Adler, with a very rounded Gull Break, I followed the full size system and panelled each rib bay individually, although I relied on a substantial ply support between the top and bottom spars

Post Reply