Slingsby T-45 Swallow ~ 1/3-scale Kit by Peter Goldsmith (Build thread by JimD)

[Tango Juliet]

This is how we spend most of our time.

[JimD]

I'm glad he has someone that cares about him!

[Tango Juliet]

I think he is too.

[JimD]

Time to cut the wing tube sockets.

Fuselage is about 7-1/2" wide and each wing has a channel for the socket that is about 12-1/4" deep.




That totals up to a length of about 32"

The carbon tube sockets are about 19-5/8" long



If you cut off a 7-1/2" piece, it leaves you with another piece about 12-1/8" long.



Now you have a tube for the fuselage and one for the wing. The other tube will be cut the same way and the 7-1/2" piece will be excess.

The solid wing rod is slightly over 27-1/4" long. This means that a spacer will need to be added inside each wing tube so that the rod will be centered within the three tubes.



We cut a 5/8" wide piece of 1/8" plywood to make a spacer for inside the wing rod tube. This extends 2-3/8" inside the tube and will be epoxied inside the tube and positioned perpendicular to the shear web that is abuts.





All of the parts are dry fit to check before adding epoxy to bond everything together.

[JimD]

Time to break out the West Systems and epoxy the tube into this wing panel.

First thing is to scuff the shine off of the tube, then mix, apply, and wait!







While that is curing, we fixed a minor issue with the stab servo covers. We noted that the screw holes in the servo covers are aligned with just the edge triangle pieces on one side. Solution was to cut small pieces of 1/8" square basswood to make these wider.

[JimD]

Time to sand out the last of the bottom fuselage sheeting!

[ARUP]

You're moving right along!

[Tango Juliet]

The advantages of a kit.

[JimD]

Epoxy is set so flipped wing over to do the other side of the wing tube.



Now that the fuselage sheeting is nearing completion, time to start thinking about adding the nose cone.



Seems like it should be simple, but orientation these large balsa blocks are sort of a Rubrics Cube!

[ARUP]

At least there isn't any color on 'em! Like 'red'!

[JimD]

Some may consider this as adding excess tail weight, but i like having these guide tubes for the servo wires rather than having those wires slopping around inside the fuselage. Yes, I know that the wires can be glued to the fuselage frame...but what if you want to remove them?

BTW...T-n-T Landing Products sells these light weight cardboard tubes:

http://www.tntlandinggear.com/phenolic_wing_tube_sockets.htm

They are at the bottom of the page of wing tube sockets.

They are 36" long, so I joined two of them to make the length needed for the Swallow.

[Tango Juliet]

Estes BT-5 model rocket body tubes work as well. And judging from the photo, the Estes tubes may be a thinner wall, and thus lighter still.

[JimD]

Before the nose blocks are added, the tow release needs to be installed. Peter has designed a simple release that uses a "U" shaped piece of wire with a pull pin type release. The wire was sanded and crimped to give better adhesion with the epoxy.


The pull pin will be on the top side of the wire "U" and the forces will be downward on the front of the "U". This means that wire behind the front bulkhead will want to move upward. To help resist this force, we cut pieces of 1/8" plywood to epoxy along the top side of the wire.



A West Systems 404 filler and epoxy mixture was used to secure the wire and plywood strips in place (first one side and then the other). Fuselage was tilted on its side so that epoxy mixture would pool nicely over the parts being secured.




Note the saw cuts we made in the top fuselage spruce stringer in order to get the necessary flex to bring the sides in to the front bulkhead. We also used water to wet the plywood fuselage sides to assist with this bending process.

[JimD]

Next step is to install the pull pin mechanism. This was made from a piece of brass tubing and 4-40 push rod wire.








And we added some filler to blend the fin into the fuselage.

[gunny11]

Nice job on the release Jim.

[JimD]

Thanks Gunny...I am really warmed up on this build so I should fly through those 2-33 wings!

[ARUP]

Yes, +1 w Gunny! The release looks familiar! lol

[JimD]

Catching up on some finishing details on the elevators. The leading edge balsa gets tapered for a top hinge line. Razor plane is way better than sanding all of this material away!

[JimD]

Now that the tow release mechanism is installed, the top sheeting can be finished out and then the nose cone blocks can be attached.



...and we made more balsa curls by adding the "V" taper to the rudder hinge line.







The shaft of the Robart Hinge Points taper toward the pivot, so we like to use the Dremel to enlarge the opening of each hole.

[Tango Juliet]

I need to pick up one of those cone shaped bits for my Dremel.

[JimD]

Back to the nose sheeting...only one more section to go after this.



Back to the wing, time now to start wing sheeting. we elected to do this in stages in order to assure that the wing does not get a twist built into it. With the wing properly held to the flat work surface and the 3/32" shim under the trailing edge of the aileron section, the first section of sheeting was glued in place to just the spar and partially to the ribs. once set, the rest will be glued.
We started with the sheeting held tightly against the previously installed spoiler pocket sheeting and then applied a weight bar to hold the rest in place.

[Stew2]

I thought I would pas this on. It is probably common knowledge, but the link below has a great set of videos on how to sheet with 1/32 plywood using water, an iron and heat activating PVA glue with an iron after it has dried, I also like how the technique releaves any residual stress in the sheeting which would otherwise contain forces that will want to warp the wing.

https://scalesoaring.co.uk/VINTAGE/HintsTips/Articles/Ply%20Panelling/Wing%20sheeting.html

[ARUP]

Post #12 shows how to put ply skin on a wing and without heat! I only did the LE but it could have been longer. The difficult part is the curved LE.

http://forum.scalesoaring.com/forum/aerotowing-slope-scale-soaring/scale-sailplanes/6911-1926-rrg-prufling-in-1-4-scale

[JimD]

Thanks for posting this...Excellent video tutorial!

The structure of the Swallow wing is very light weight, but as such, I don't think the pressure applied with the iron would be tolerated. Peter suggests attaching the sheeting at the spar and then flipping the wing over and gluing the sheeting out to the leading edge while supporting the sheeting against the workbench surface. This worked well for us, but it did require CA glue.

The sheeting kicked up very slightly along the back edge, so I did use the hot iron technique to get the sheeting nice and flat over the spar. This was an area where we could put significant downward pressure on the iron without fear of collapsing the underlying structure...and it worked like a charm!

The other neat thing in the video was tapering the edge of the plywood skins so as to create an overlapping seam instead of just a butt joint. This will be my preferred method from here forward! Simple, easy, and a much better way. Will be doing this where the inner and outer plywood skins meet on the Swallow.

[JimD]

We sanded a taper on both ends of the plywood sheeting so that the joint between the inner and outer sheeting would have a nice overlap.




The leading edge cap was attached so that the bottom edge rested against the work surface. This allowed for us to use the hot iron method for applying the plywood sheeting.






Glue was applied and spread evenly and the ribs/spar and sheeting then allowed to dry. The iron was set to highest setting.



Water was spritzed onto the plywood sheeting with a re-purposed eyeglass cleaner bottle and the iron was used to press the plywood down against the spar first, then out each rib and then on to the leading edge. Pretty easy, and we got a neat joint between the inner and outer sheeting.