People are joining and then emailing me to ask for plans. We do expect you to contribute to the community before being granted this option. I have added a section to the rules of the forum to cover this.

MU13 Charlesworth

Let us all watch your new project progress.
John Vella
Posts: 223
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

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
General view.
General view.
General of fin and rudder fitted.
General of fin and rudder fitted.
Pinned fin
Pinned fin
Brass retaining pin fitted
Brass retaining pin fitted
Lower pintle fitted
Lower pintle fitted
Upper pintle fitted
Upper pintle fitted

John Vella
Posts: 223
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

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
Ply skin glued in place
Ply skin glued in place
Tailplane finished
Tailplane finished
Ply doubler for hinge
Ply doubler for hinge
Tailplane  loose fit
Tailplane loose fit
Front view
Front view
Top view
Top view

John Vella
Posts: 223
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

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
Spar mounted on joiner
Spar mounted on joiner
Ply scarf joint doubler
Ply scarf joint doubler
Brass joining box in place
Brass joining box in place
Spar tips steam bent and bonded
Spar tips steam bent and bonded
Right spar complete and components for the left
Right spar complete and components for the left
View from the tip
View from the tip
Spar on side from root
Spar on side from root

SteveArchibald
Posts: 34
Joined: 18 May 2018, 06:41
Location: Wonthaggi

Re: MU13 Charlesworth

Post by SteveArchibald »

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: 223
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

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
Level set to check symmetry.
Level set to check symmetry.
The bald patch is definitely  growing.
The bald patch is definitely growing.
The dyhedral is about 2.5 degrees.
The dyhedral is about 2.5 degrees.

John Vella
Posts: 223
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

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
Washout taper in place
Washout taper in place
Ribs attached
Ribs attached
Left root rib clamped for alignment of riblets
Left root rib clamped for alignment of riblets
Riblets and spreader tube fitted
Riblets and spreader tube fitted
Skirt sheeting done
Skirt sheeting done
Canopy frame complete
Canopy frame complete

John Vella
Posts: 223
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

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
Rear joiner 1.5mm ply boxing.
Rear joiner 1.5mm ply boxing.
Aileron servo installed.
Aileron servo installed.
False leading edge glued up.
False leading edge glued up.
5mm×3mm spruce drag spars
5mm×3mm spruce drag spars
1.5mm ply facing fitted.
1.5mm ply facing fitted.
Spoiler servo installed.
Spoiler servo installed.
5mm sq spruce  for aileron box.
5mm sq spruce for aileron box.
Tips in balsa ply lamination.
Tips in balsa ply lamination.
T.e to be trimmed and ailerons to be cut out.
T.e to be trimmed and ailerons to be cut out.
Tip ready for trimming.
Tip ready for trimming.

User avatar
RobbieB
Posts: 548
Joined: 07 Mar 2015, 22:22
Location: North West

Re: MU13 Charlesworth

Post by RobbieB »

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.

User avatar
Barry_Cole
Posts: 1331
Joined: 10 Mar 2015, 09:30
Location: Hampshire UK

Re: MU13 Charlesworth

Post by Barry_Cole »


John Vella
Posts: 223
Joined: 20 Mar 2017, 22:09
Location: UK

Re: MU13 Charlesworth

Post by John Vella »

Thanks for the advice. I will replace with twisted triwire. No point taking a chance. Regards John.

Post Reply