MU13 Charlesworth

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John Vella
Posts: 110
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella » 27 Apr 2018, 15:17

The next job was the elevator hinges. They were cut and laminated from pieces of 1.5mm Epoxy board. The pins are 2mm steel and a key step made to locate the hinge in position in the slot on the tail spar. The pins are glued in a slot in the rear of the elevator spar. The elevator was fitted on hinges on the tailplane for final profiling. The rudder was built next in a traditional balsa ply balsa sandwich. The ply was laminated from 2 pieces of 0.8mm ply. The rudder spar from 13mm×20mm medium hard balsa.the ribs from 2mm medium hard balsa. The construction was a fiddle but the weight was very light at 1.5 oz complete awaiting its pintle hinging.
Attachments
20180415_142010.jpg
Glass hinges
20180421_143519_001.jpg
Rudder basic structure
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Rudder complete
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On electronic balance at 1.5ozs.
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Tailplane jigged for profiling.
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Rudder basic components

John Vella
Posts: 110
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella » 14 May 2018, 16:28

The Fin construction was next. All ribs were reprofiled then the 2mm hard balsa false LE glued to form the frame with the base box and joining tongue fitted. The tongue was stiffened with glass over the 3mm ply. The joining pin is 3mm brass locating through a ply box glued into the rear 3mm balsa sheeting. The rear fin joiner is a 2mm steel rod locating into brass tubing bonded to the fin spar and the rear fuselage bulkhead respectively.
The Pintle hinge system is made with 10g brass on the bottom and 20g brass on the top. A 20mm long steel pin on the bottom and a 10mm pin at the top locate into brass tubes fitted in the rudder post. All facings are reinforced with 3mm ply capping.
On rigging the rudder more profiling was required. So off came the 0.4mm ply gussets and then reglued when the fit was right.
For a little extra work one ends up with a light structure which deriggs easily which is good for transportation as this vintage large wing area has rather large tail surfaces !
Attachments
3.jpg
General view.
6.jpg
General of fin and rudder fitted.
1.jpg
Pinned fin
2.jpg
Brass retaining pin fitted
4.jpg
Lower pintle fitted
5.jpg
Upper pintle fitted

John Vella
Posts: 110
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella » 11 Jun 2018, 12:12

Back to the build after holidays and other distractions. The tailplane and elevators were fabricated in The usual Charlesworth light weight design. The stiffness of a pretty light structure of the tailplane is given by the 0.4 mm ply D box skins. Hopefully the pin hinges are fit and forget. The elevator spar is reinforced by 0.8 mm doublers at the hinge points. The area of the tailplane is huge by modern standards and a total weight of 5 ozs is impressive. I am going along with the detachable tail surfaces as they could be vulnerable to transit damage. Also storage can be a problem with these vintage gliders.Yes I am running out of fuselage hanging space. Heyho wings next job.
Attachments
20180606_180738.jpg
Ply skin glued in place
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Tailplane finished
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Ply doubler for hinge
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Tailplane loose fit
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Front view
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Top view

John Vella
Posts: 110
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella » 21 Jul 2018, 19:01

The spars are constructed from Baltic Pine 4mm section from 2.4 m length, hard balsa webs from 1.5mm 48 inch by 4 inch stock. This gives a spar with no scarfs and only one scarf on the webs. The spars were matched for straight grain and shaped to taper and the ends were steam bent to follow tip curve profiles. The 15mm brass box is supported in 4 ply cross pieces, 2 are 3mm and The middle 2 are 1.5mm ply. Every 30 cms there are 2mm hard balsa braces to support the side webs. The set of the spars is 3 degrees dyhedral which is set with the spar in place on the glider before the second side web is bonded. The spar box was held on the building board with weights while the resin set and luckily has come out straight. If you like building and take your time Charlesworth designs produce a very satisfying model. If it flies as well as my K8 the effort will be worthwhile.
Regards John.
Attachments
20180718_134807.jpg
Spar mounted on joiner
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Ply scarf joint doubler
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Brass joining box in place
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Spar tips steam bent and bonded
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Right spar complete and components for the left
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View from the tip
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Spar on side from root

SteveArchibald
Posts: 6
Joined: 18 May 2018, 06:41
Location: Wonthaggi

Re: MU13 Charlesworth

Post by SteveArchibald » 25 Jul 2018, 05:58

Hi John,

I am new here and just poking around to get the lay of the land so to speak. Great build and the MU is one on my future build lists. Fabulous work.

Kind Regards
Steve

John Vella
Posts: 110
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella » 04 Aug 2018, 16:36

Hi Steve , thank you for the encouraging words. We are having your Australian weather here ! This certainly slows the build with more good flying weather. Here are some photos of the wing spar set up. Luckily they came out weight matched and straight. Now the fun really starts with the wing build.
Regards John.
Attachments
20180804_093737.jpg
Level set to check symmetry.
20180804_093803_001.jpg
The bald patch is definitely growing.
20180804_094019.jpg
The dyhedral is about 2.5 degrees.

John Vella
Posts: 110
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella » 16 Sep 2018, 12:56

The right wing construction is started with the ribs glued to the spar box rear and front. A washout taper to 6mm at tip is jigged from the start of the aileron rib. With an MU13 canopy on loan to copy the canopy frame was constructed next. The instrument panel and rear frame are 3mm ply, with the side rails constructed from 1.5mm ply and balsa composite. The riblets are 3mm ply , with 2.5 mm spruce side bars attached. The spreader tube is 4mm od brass tubing which is load bearing on keeping the wings apart. The attachment is with spring clips at the rear and a magnet under the instrument panel. 0.8 ply is used for the skirt sheeting. Just the painting and glazing is left to finish.
Attachments
20180815_115920.jpg
Washout taper in place
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Ribs attached
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Left root rib clamped for alignment of riblets
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Riblets and spreader tube fitted
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Skirt sheeting done
20180906_124741.jpg
Canopy frame complete

John Vella
Posts: 110
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella » 09 Nov 2018, 16:45

Right wing construction basic structure was done, with the trailing edge made from balsa ply balsa composite. Abit of regiging of ribs was required to get a good alignment of the washout . The rear joiner brass box was boxed in with 1.5mm ply. The aileron servo was installed on a removable hatch, along with the spoiler servo. The false leading edge of 1.5 mm balsa was glued. The drag spars of 5mm ×3mm spruce were fitted.The facings are 1.5 mm ply.A departure from the original design was the replacement of the 0.4 mm ply facings between the ailerons and rear wing box with 1.5mm balsa sheet. So the 5mm sq spruce spars had to be positioned further apart to accommodate the balsa facings.The facings top and bottom would still be retained for the continuity of the 0.4 mm ply wing skinning. The wing tips are constructed with laminations of balsa sandwiching 0.8 mm ply. So at this stage the t.e and tip need final profiling and then the ailerons cut out and facings fitted.
Attachments
20181001_135332.jpg
Rear joiner 1.5mm ply boxing.
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Aileron servo installed.
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False leading edge glued up.
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5mm×3mm spruce drag spars
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1.5mm ply facing fitted.
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Spoiler servo installed.
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5mm sq spruce for aileron box.
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Tips in balsa ply lamination.
20181109_103005.jpg
T.e to be trimmed and ailerons to be cut out.
20181109_102918_001.jpg
Tip ready for trimming.

User avatar
RobbieB
Posts: 403
Joined: 07 Mar 2015, 22:22
Location: North West
Contact:

Re: MU13 Charlesworth

Post by RobbieB » 09 Nov 2018, 17:16

John, been watching your build with interest.

Not wishing to be a killjoy here, you might want to consider changing those straight servo extension leads for twisted triples. They might just be fine but twisted will obviate any cross talk between cores and the subsequent servo problems.

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Barry_Cole
Posts: 1096
Joined: 10 Mar 2015, 09:30
Location: Hampshire UK

Re: MU13 Charlesworth

Post by Barry_Cole » 09 Nov 2018, 17:34


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