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MU13 Charlesworth

Let us all watch your new project progress.
John Vella
Posts: 246
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

Here we go with some more progress over the last few weeks. The top sheeting of 0.4mm ply was glued on with 6mm balsa rib doublers at joints. All reprofiling of ribs etc were with slivers of balsa soaked in cyano for a durable sandable finish. PVA glue was used on skinning with the hot iron method. Around the tips Aliphatic (yellow) glue was used for feather sanding to profiles. Aliphatic glue was used on most of the structure including the rib caps. The Delux Materials Resin does have a fast grab time if used in 25 deg temperature of my model room. The photo of the root end of the Aileron shows the structure of the balsa facing on 5mm sq spruce boxed by 0.4 mm ply top and bottom. 0.4 mm ply cap strips flair into the TE of balsa 0.8mm ply balsa sandwich. 6mm thick ply blocks were glued to the root ribs to take screw hooks for rubber band wing retainers.The bottom sheeting was then added with rib caps and capping of the cutouts and covers for the spoiler and Aileron servos. The top skin is joined at rib 28 to accommodate the compound curve at the tip. The gentler curve underneath allows a continuous skin to the tip. So next year the balsa leading edge and root rib capping will complete the starboard wing. A HAPPY NEW YEAR to you all.
Attachments
Balsa cap fillet on top drag spar
Balsa cap fillet on top drag spar
Top 0.4 mm skinning  to  balsa rib doubler.
Top 0.4 mm skinning to balsa rib doubler.
Top skinning on
Top skinning on
Aileron Root view.
Aileron Root view.
Rear attachment  block.
Rear attachment block.
Front block and 2.6mm  spruce support strips.
Front block and 2.6mm spruce support strips.
Lower skins and capping completed.
Lower skins and capping completed.
Top skin tip view.
Top skin tip view.
Bottom skin  tip view.
Bottom skin tip view.

John Vella
Posts: 246
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

Cliff, happy New Year. At this point I would like to add my thanks to you for all your hard work . I am struggling with an MU13 scheme . With my K8s you are spoilt for choice. Any suggestions for a MU13D scheme are welcome. Regards John.

John Vella
Posts: 246
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

The next little job is fitting and shaping the leading edge. It is from 4ft long 6mm medium hard balsa. Aliphatic resin was used and pinned in place . The profiling started with the trusty David Plane then sanding with the butting sheet ply protected with insulating tape. The Gottingen 540 profile is pretty blunt and crude by modern day standards, but does the job and is scale. (Scale Police take note). Next the wing tips were profiled with the 0.4 mm ply blending into the balsa. The final constructional job was the root rib facings made from 1.6 birch ply, and made in 2 sections to account for the bend at the canopy cut out. On offering up the wing on its joiners the fit looked pretty good. The starboard wing including servos comes out at 38 ozs. On most of my gliders the wings weigh about half the gross weight of the complete model. So it looks like a target weight of around 10lbs might be achievable.
Attachments
Leading edge pinned up.
Leading edge pinned up.
Leading edge profiling with protective tape.
Leading edge profiling with protective tape.
Root end facings fitted and held in place.
Root end facings fitted and held in place.
Wing tips profiled.
Wing tips profiled.
Root view with facings done
Root view with facings done

John Vella
Posts: 246
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

This an update on the slow build of the MU13 wings. The problem I am finding is the time taken in reprofiling the wing ribs. The humps and bumps occur on the top rib surface only on the plans which the Laser Cutting follows exactly. The strange thing was the fuselage and empenage were very accurate, and went together a treat. I like a challenge but the time taken to reprofile the ribs is testing my patience. What would we do without the trusty Straight Edge and a good set of Glasses? Hopefully the MU13 will fly in the Spring of this Year.
Attachments
Wing rib 8 is typical of the problem top surface.
Wing rib 8 is typical of the problem top surface.

User avatar
B Sharp
Posts: 776
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: MU13 Charlesworth

Post by B Sharp »

John, the straight edge is mandatory but the glasses must be filled with a good malt whiskey.
Brian. :D :D :D

John Vella
Posts: 246
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

Brian a glass of Glenmorangie would not go amiss after this build. 😁😁

John Vella
Posts: 246
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

Here we go again ,with the forecast showing Spring returning soon and flying weather, is an update on the left wing build. I decided to construct the rear structure to the spar first and build the front ribs afterwards on the second wing. The false leading edge is 2 mm medium hard balsa .The front root rib was partially cut through for the cockpit angle ,and jigged on the fuselage rib to get exact alignment before fitting on the wing and glued. The trailing edge and tips were the balsa 0.8 mm ply balsa laminate. All ribs were reprofiled in situ.
Attachments
Rear ribs and trailing edge fitted
Rear ribs and trailing edge fitted
Tip view of rear structure
Tip view of rear structure
Front ribs added
Front ribs added
Root awaiting front rib.
Root awaiting front rib.
Front rib jigged to fuselage for algnment
Front rib jigged to fuselage for algnment
Front rib glued into place
Front rib glued into place
Wing with false LE fitted and profiled
Wing with false LE fitted and profiled
Wing tip profiled and gussets added.
Wing tip profiled and gussets added.

John Vella
Posts: 246
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

With flying weather arriving the build is progressing slowly. The fitting of the 5mm × 3mm spruce drag spars are next. Then the 1.5mm ply inter rib webbing. On this wing there is continuous webbing between rib 2 and 3 with a slot for the rear brass box. The brass box is loose fitted ,.then the left wing is mounted and jigged with the fuselage and right wing. The brass box is glued in position with 30 minute epoxy. Care was taken with wing root alignment to allow for spacing when the ply facing rib is fitted. The next job is the 1.5mm ply boxing the rear incident box. Then the skinning of the left wing will commence.
Attachments
Drag spars and webbing fitting.
Drag spars and webbing fitting.
Wings rigged on fuselage.
Wings rigged on fuselage.
Wing jigged with gap for facing rib.
Wing jigged with gap for facing rib.
Brass box glued in position.
Brass box glued in position.
View from right wing tip.
View from right wing tip.

John Vella
Posts: 246
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

Here we are Bank Holiday and a heat wave ! Model room temperatures are still reasonable so on with the build. The left wing build was done as per the right with the last job being the root facing rib out of 0.8mm ply. The wings were rigged to check any high spots on the wing root. The time consuming job was the profiling of the hard balsa leading edge. The next job is covering in Oratex. The colour scheme German circa 1938. Regards to all the builders out there, John.
Attachments
Glider laterally balanced
Glider laterally balanced
Side view
Side view
Checking the root gap for the facing rib
Checking the root gap for the facing rib
Trailing edges align.
Trailing edges align.
MU-13 rigged
MU-13 rigged

Ben Matu
Posts: 4
Joined: 25 Aug 2019, 09:47
Location: RLP

Re: MU13 Charlesworth

Post by Ben Matu »

Is this an Kit or is the Plan avible to buy? Im looking for an new projekt.

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