1932 BS2 'Balestruccio' in 1:6 Scale

[ARUP]

I bought the very nice book 'Italian Vintage Sailplanes' by Vincenzo Pedrielli with three views by Francesco Camastra. There are some very beautiful and unusual sailplanes shown in this book. The 'Balestruccio' immediately caught my eye. It is certainly a 'bella donna'! Camilla Silva designed this to be a record breaker which it did. To me, a strut braced gull wing sailplane with a skid, covered in plywood is the most beautiful thing! The 'Balestruccio' has those bases covered in Spades!!! It has a large aspect ratio which will only help with performance. It is a flapped wing so that is helpful trimming for duration and in landing. The full scale had an 18 meter span so that puts the model at 3 meter span or just over 118". It is my second scale sailplane built. I used three views in Vincenzo's book to draw the plans. I met Vincenzo at the Soaring Museum at Elmira, NY. I brought the 'bones' of the 'Balestruccio' for him to see. He was very gracious with his compliments.He signed my book and we had a nice friendly conversation on the museum's front porch. He told me that my model was going to be the first built using information from his book! That was pretty neat to know, too! I used the airfoil on the drawings. It is slightly undercambered on the bottom surface. The airfoil from the strut attach point of the wing to the tip was modified by me as I had it progressively change until it was fully symmetrical at the tips.

I hand drew the plans then made a form in order to fabricate the curved upper and lower nose bows. I stained the wood before using it to avoid 'the pox', i.e., glue not allowing stain to penetrate glue joints. I used H. Behlen water based stain so that the gluing of joints won't be compromised like they would be if using oil based stains. The fuselage side 'ladder' crutches built over the plans. All wood parts put in scale locations as much as could be determined. Why re-invent the wheel?

[ARUP]

The fuselage side crutches were placed over the plan. The fuselage has a trapezoidal section with the lower portion being more narrowed than the top so the crutches were jigged at the appropriate angle with the aid of the triangle. The bow laminations were grooved so that CF tow could be epoxied in place as reinforcement for the tow release. The release was made from wire, brass tube and sheet and a pen spring. Looks like ship building from days of yore!

[ARUP]

The bows were scarfed onto the fuselage frame then more CF tow epoxied to tie it all together. Close up of joinery. I love this stuff! Everything gets attached to the basic fuselage 'box'. The center pylon and its supports cut into the frame. Rib templates from micarta to make center section and outer panel ribs.

[ARUP]

The photos of the build might meander a bit from one portion of the build to the next but that is how I do it. Sometimes parts have glue drying so I do something else instead of standing around. Here are tail feather plan pictures. The pink eraser is a very well used tool! The ribs were set up in incidence meter so a jig could be made. The elevator push rod had to be fabricated 'bullet proof' since access would be impossible. The 'Balestruccio' has an elegantly narrow fuselage which makes for some very tight fittments. To clear the fin post the horns of the SIG control horn were bent as shown in the side view picture.

[ARUP]

A stab incidence jig was made. I wanted to make sure the model didn't fly 'tail low'. The completed model flies great but the stab incidence could use to be adjusted to +2 degrees. The reason for that is the stab and elevators don't align at best trim settings thus creating drag. I'm a little picky! The 1:4 version will get the correction. The 'stub' stabs were glued in place maintaining alignment until glue dried. I decided to make the stab-elevator assembly removable from the airframe. The SIG horn got modified. Square drives were soldered to it and receivers glued into the elevators. Fin rudder built.

[ARUP]

Gluing square drive receivers into elevators with epoxy and CF tow for strength. The temporary brass tube between them maintains alignment while the epoxy cures. Checking fin fit relative to stab and elevators. The fuselage was jigged so the fin could be glued squarely in place. CF tow added to rear of fuselage before adding the 1/64" skins.

[ARUP]

CF epoxied onto tail end before putting on 1/64" ply skins. Pull-pull parts for rudder. Here they are in place and the elevator push rod can be seen, too! More 1/64" ply added. The top longeron has to be straight. Balsa added along the top side of upper longerons and lower side of lower longerons to be sanded fair. The 1/64" ply needs something to which it can attach.

[ARUP]

Constructing the canopy/ hatch. Basic hatch shown along with 1/8" marine ply keel parts. Strut attach fitting from sheet steel mounted to block. What is that last picture?

[ARUP]

The part in last picture above is just balsa filler. Relief cuts allow it to conform to the curves on the forward longerons. The ply won't stick to an edge very well so these filler pieces get added and sanded fair to the longerons and formers. More ply skins added. Use 'manila folder' card stock to make patterns. The strut attach fittings got 'gussetted'. Is that a proper word? Brass tubes were threaded 4-40 for skid mounting.landing. Bass blocks support the tubes on the keel.

[ARUP]

The skid is mounted in a bass block. You can see the tight fit of the elevator push rod clevis. The rudder horn is my old stand by of bent music wires soldered together. Their ends have brass tubes soldered onto them. The tubes are flattened on one end then drilled for the cables to attach. All cable adjustment is inside the fuselage to keep everything 'clean' outside. The basic fuselage is shown. The wings are started. The outer panel ribs were made after these 1/4" balsa templates were sanded fair. You can see how the washout is 'induced' by the shape of the ribs.

[ARUP]

Marking patterns for the locations of the spar slots. Tracing around the patterns and marking the spar slots for the outer, tapered, panel ribs. The ribs were pinned onto a jig then the ribs were gently sanded fair. This was a delicate process since pins were the only thing holding the ribs in place. A straight edge was laid down to the markings to guide the 'spar slotting tool' which was made just shy of the proper width for the spars. You can see the 'spar slotting tool' captured between the straight edge and the Mahogany block. A 'Depth Tool' is just a piece of spar stock used to check sanding progress. The outer panel spars were scarfed together from spruce and hard balsa. The scarf joint was overlaid with 1/64" ply both sides. The stronger spruce portion of spar goes inboard.

[ARUP]

It's starting to look like a wing! There's a train a-comin'! The wing has movable surfaces along its whole TE so the rear spar was strategically located. The second rear spar was let into the wing using the Zona saw as a spacer since the saw will be used to cut the flap and aileron free anyway. The wing flipped over and the whole process from gebtly sanding ribs fair to setting spars was repeated. The LE was marked using a straight edge then the outer panels were placed bottom surface to bottom surface so the rib noses could be cut away. The LE will get added. The wing tips were added. Slotting ribs for spars was easy for the center section panels!

[DennisB]

What a wonderful thing to see there are still superb craftsmen willing to take on vintage projects like this. Fred China would be very proud. Vincenzo's book is fantastic, I have picked a few that would make great subjects.

[ARUP]

DennisB, that is a very nice compliment! Thanks! I've always liked antique types of aircraft. Sailplanes have always been a fascination and when I obtained various books their content and my imagination really took hold. Aerotowing seemed like a lot of fun and the low key non-competition aspect of it really had an appeal. Reality bore it out. What a fun bunch of folks! Then, seeing some of Fred China's models really lit my fire so here I am! Thanks again... I really appreciate it!

[ARUP]

Outer panels framed. The tips were cut off and an 'extension' piece of balsa was glued and sanded fair. The tips will get put back on after the 1/64" ply glued to wing. Inner panels were easy! I made this neat little dihedral angle gauge. Flaps and ailerons cut free so that shear webs and filler blocks could be glued in place. The filler blocks receive, wing joiner tubes,alignment pin, its tube and hinges.