Preliminary steps for covering the Ressu (Snoopy) fuselage frame

Sunnuntai 27.10.2024 - Tuesday Club member

Suomeksi

The fuselage of the Snoopy experimental aircraft (OH-XEA) was covered with fabric. When Aviation Museum Society Finland received the Snoopy two years ago, the fuselage was totally stripped of covering fabric. Therefore, the fuselage will be covered at the Tuesday Club as it originally was. Luckily we have some good photographs of the Snoopy at our disposal to guide us with the covering. So to work.

The whole fuselage frame of steel tube has been cleaned of rust during the autumn, given a layer of lacquer and finally painted with red Isotrol- paint. These jobs have been necessary for starting the work on the fuselage frame. These include the installing of the long wooden battens along the sides and upper surfaces of the fuselage frame and the partial covering of the fuselage frame steel tubes with fabric strip.

Metal brackets with 10 mm slots have been welded to the structure of both sides and the upper surface. Thin wooden battens have been fastened to these brackets along the whole of the rear fuselage. The purpose of the battens is to keep the covering canvas separated from the fuselage frame trusswork. Otherwise the metal would start to “eat” into the canvas, especially when rusting.

In order to prevent direct contact between the canvas and the longitudinal steel tubes at the upper and lower corners of the fuselage frame, cloth strip had been tied around the tubes. There were still remains of these strips left in the tail and vertical stabilizer of the Snoopy.

Next we started making the long protecting wooden battens. We found suitable material to make the battens at the restoration workshop’s woodware storage at the Finnish Aviation Museum. The battens were cut to measure and shaped to fit the brackets. At fitting the battens the brackets were squeezed tight to them. The batten was locked into place with small nails. Finally the battens that were fastened to the brackets, were protected with nitrocellulose lacquer.

Along with making the battens, we started covering the steel tubes of the fuselage frame with 20 mm wide cotton strip or tape. We bought that from Eurokangas. When the shop assistant queried what we needed it for, we said that it was used for covering a museum aircraft. The assistant was surprised but interested, so we briefed her in more detail about the purpose of the fabric strip. We must have been the first customer of this sort.

The ribbon was wound around the fuselage tubes to form a solid surface of fabric around the tubes. We wound the fabric strip to overlap the edge by about 5 mm. The stripping thus became solid, without any metal surface being visible. On the lower surface of the fuselage, without the wooden batten, we wound the strip on the lower part trusswork as well.

All the strip-covered surfaces were finally treated with nitrocellulose lacquer, which simultaneously glues the strip onto the tubes and later functions as an adhesive surface for the canvas covering. The covering canvas is tightened with that very same nitrocellulose lacquer.

Photos by Lassi Karivalo.

Translation by Matti Liuskallio.

The surface treatment of Snoopy?s fuselage framework

Perjantai 25.10.2024 - Tuesday Club member

Suomeksi

The fuselage framework of the experimental aircraft OH-XEA “Snoopy”, currently being restored  by the Tuesday Club of Aviation Museum Society Finland, was without its fabric covering when the Society received its ownership. When and why the fabric covering had been stripped off, is not known. Anyway, Snoopy had been stored without its covering for a long time, as its fuselage framework, welded of 13 mm steel tube, was in such thick rust.

The first stage of restoring the fuselage framework was to clean it from rust. Cleaning the steel tubes until clear metal appears is however unnecessary, as removing the superficial rust will suffice. When the tube surface feels very smooth to your fingers, it is clean enough. For the purpose, we used sandpapers of various grades as well as scrubber sponge. The grinding dust was wiped away carefully with rags of fabric and solution mixed of Sinol spirits and water.

Not grinding the fuselage framework until clear metal shows is because for priming the tubes for their surface paint, we use the clear Isotrol lacquer (Klarlack Grund). This lacquer penetrates through possible rust to the surface of the tube, stopping the rusting process. The surface can then be painted directly on the lacquer.

After the whole fuselage framework was cleaned from surface rust, we then treated it by a thin coat of Isotrol, covering fully the steel tubes and other metal parts and giving the tubes a nice shiny surface.

After the lacquer had dried, the fuselage framework was painted with Isoqaurd Panzer, an alkyd oil paint for metal. Originally in the 1960’s, the fuselage framework had been painted with red Ferrex anti-rust paint, still visible as residues in the tubes. Simulating the red Ferrex, the Isoquard paint was tuned to the same tone of red. An exception was the landing gear that was painted with black Isoquard, according to its original black paint.

The fuselage framework surface treatment is now done.  The restoration work of Snoopy’s fuselage will next proceed with the cockpit, as well as measures priming the fabric covering of the fuselage.

Photos by Lassi Karivalo.

Translation by Hannu Mononen.

Refurbishing the passenger seats, part 2: Padding

Maanantai 21.10.2024 - Erja Reinikainen

Suomeksi

Refurbishment of the Caravelle’s passenger seats is under way. We repaired and washed original seat covers and now padding for 22 seats has been acquired. The refurbishment work includes four seat rows, i.e. 8 seat frames with a total of 19 individual seats. These include five 2-person seats and four 3-person seats. We are still debating about adding 2+2 seats to the open rear cabin area.

This is how the seats will be placed in the cabin. When this picture was taken the cabin partitions and ceiling material had not yet been installed.

This blog talks about replacing the seat padding.

We have only one original seatback padding piece, made of foamed plastic. We had to order new padding to fit the seats and the original seat covers. Muovikum Oy from Raisio cut new seat cushion and seat back padding for 22 seats, based on seat measurements and on the test versions we had prepared. The new padding was delivered in the beginning of August.  

The seat cushion (40x40 cm) was cut from 10 cm thick E30 quality foamed plastic. Its thickness at the rear edge of the seat is about 5 cm and at the front edge 10 cm. The cushion will be covered with thin felt plate to hide the bevelling in the material, needed for the change in the cushion thickness. With the felt plate the seat cover will also fit better and look neater. This finishing job we will do ourselves.

The seatback padding is made of 5 cm thick E30 quality foamed plastic. The size of the padding is about 41x75 cm. Preparing new padding for the seatback proved to be rather arduous because at the top there is a piece of foamed plastic, placed horizontally on top of the seatback edge as padding and supporting the seatback padding in its position. Originally this supporting piece has been made of hard foamed plastic and had a rounded shape. To save costs we didn’t acquire similar material or had it cut to shape but made it from E30 foamed plastic.

Left: The upper part of the original seatback paddin. Right: The first prototype of the upper part of the new seatback paddin.

First we made some prototypes of the supporting piece to find the right shape and make sure the seat cover fits nicely on the padding. Fortunately Muovikum had given us the waste pieces from cutting the seatback padding so there was plenty of foamed plastic for prototype tests and practising with the spray glue.

The parts for the upper edge of the seatback padding were cut from foamed plastic waste pieces.

After three test rounds, we had the seat cover top shape and angle right and “series production” could be started. Two foamed rubber pieces, cut to shape, were glued to the top edge of the actual seatback padding, using spray glue purchased from Muovikum. Spray gluing proved to be rather messy, fortunately we could work outside.

New seatback padding on the ”gluing line”, with finished items drying in the background.

The following step in the padding will be to cover the seat cushion with the 20 mm thick felt plate to make the seat cover look good.

We aim to get the seat frame refurbishment as far as possible this autumn. Hopefully we will have one refurbished demo seat ready before the winter, fitted with new padding and “dressed” in repaired seat covers.

Photos by Erja Reinikainen except if otherwise mentioned.

Making the engine cowlings for the Snoopy started with cardboard templates

Maanantai 30.9.2024 - Tuesday Club member

Suomeksi

OH-XEA Ressu (Snoopy) experimental aircraft from the 1960s that we are restoring, was equipped with a Continental A 65 engine. To replace the Snoopy’s lost engine we received, as a donation, a similar engine. The engine cowlings have vanished during the decades as well. So they’ll have to be made anew.

Photo by Esko Keskinen.

From the photographs we have at our disposal the size and form of the cowlings come out very well. The cowling is two partite. The larger, upper cowling, covers the engine from above and the smaller one covers the front part of the engine. The cowlings have been made of sheet aluminium, so that’s what we’ll be using too, utilizing 1 mm thick aluminium sheet. The fact that the original cowling rack fastened to the engine, has survived, will facilitate the making of the cowlings.

The constructing of the cowlings was started by cleaning the rusty cowling rack and painting it with black Isotrol paint. Black, because the original black paint was still faintly to be seen. The freshly painted rack was fastened to the Continental engine donated to us. The first phase to make the cowlings proper, was to make patterns or templates out of cardboard to fit above the rack. According to the cardboard templates aluminium blanks will be cut to be moulded to their final form.

Making the templates was started with the upper cowling. The template was made out two pieces of cardboard cut from a roll. First the tentatively cut left-hand side was fastened to the pegs in the protective rack. After that the same procedure was repeated with the right-hand piece of the template, after which the left and right-hand halves of the template were taped together. The united template of the cowling was modified by cutting and taping extra pieces to reach the final shape of the Snoopy’s cowling.

At this stage the making of the cowling template, covering the front end of the engine, was commenced. A piece of cardboard cut from the roll was bent against the front of the engine. The piece was gradually cut to form and the cardboard was attached to the pegs in the rack. By cutting suitable extra pieces of cardboard to the front cowling it was united with the upper cowling.

Thus, like a patchwork quilt, the cardboard template was built around the Snoopy’s Continental engine prior to making the aluminium cowling. The next stage will be to transform the shape of the cardboard template into aluminium sheets.

Photos by Lassi Karivalo except if otherwise mentioned.

Translation by Matti Liuskallio.

Refurbishing the passenger seats, part 1

Sunnuntai 29.9.2024 - Erja Reinikainen

The interior work in the Aviation Museum Society Finland owned Sud Aviation SE 210 Caravelle III at Turku airport is under way and the passenger seat refurbishment has also been started. There will be four rows of seats in the cabin, with a partition at the back, separating the open area in the rear section from the actual cabin part. The front seats on both sides of the aisle will be double seats, but the other three rows will have the original lay-out with three seats on the RH side and double seats on the left. We have original textiles and seat belts for fitting about twenty seats.

This blog talks about starting the seat refurbishment.

All the seat frames in our possession have suffered from the decades of storage and they will have to be repaired. The work was started by choosing from our storage sea container eight seats, which were in the best condition. In good weather the repair and refurbishment work has been done outdoors, with the Caravelle’s wing sheltering a little from the heat of the late summer sun. On rainy days we have been using the cabin of the DC-3 (registered as DO-5 in the Finnish Air Force), standing next to the Caravelle, as a workspace.

The condition and functioning of the seat back, arm rests and seat table are checked and tested. If some part is not moving as it should, the aim is to repair and fix it to functioning condition. Especially the arm rests are broken or not moving. The plastic covers at the end of the seat frame, under the arm rest, have suffered from transport and storage, some of the covers are broken.  The seat back webbing is made of rubber belts, some of them have dried and crumbled and the metal hooks, fastening the webbing to the seat back frame, have broken. It seems that during their lifetime the seats have been repaired several times, mainly the arm rests and the seat back webbing.

Photo by Erja Reinikainen.

Fortunately we have six more passenger seat frames stored in the sea container and it has been possible to dismantle armrests, seat tables, seat frame plastic covers and seat back webbing from them to use as spare parts for the seats under refurbishment. Up to now the functioning parts on a couple of seats have been checked and refurbished, faulty and broken parts have been dismantled and replaced with spare parts – and the work continues. Seat tables have been overhauled and cleaned. In some seats the seat back structure, made of light metal, has broken and it has been strengthened with a patch sheet. The life vest pouches were removed from the seats. We don’t have any life vests and the pouches under the seat obstruct the refurbishment and painting of the seat frame.

The following step will be the sanding of the seat frame legs, where the paint is flaking and peeling off. The legs will be painted using paint which matches the hue of the plastic cover on the seat end.

Photos by Jouko Tarponen except if otherwise mentioned.

Continental A 65-8 engine for Ressu "Snoopy"

Sunnuntai 29.9.2024 - Tuesday Club member

Suomeksi

The OH-XEA “ Snoopy” experimental aircraft, built by the Hietanen brothers from Turku in the 1960s, now under restoration at the Tuesday Club, had a Continental A 65 engine. Before the Snoopy it was in the Piper Cub aircraft of the Turku Flying Club. The engine on the Snoopy hasn’t survived, and there is no knowledge about its fate. So we started to ask around whether a surplus engine was to be found somewhere. We could do with quite a dilapidated engine, since we weren’t restoring the Snoopy to an airworthy condition.

Photo by Esko Keskinen (1969).

Our query was successful, as we were offered the Continental A 65-8 engine of the PIK-11 “Tumppu” (OH-YMD) single-seat sport aircraft that had crashed in Mikkeli on 7 August 1999. The engine was damaged and burned in the accident. However, it could be refurbished to look externally intact, to be attached to the nose of Snoopy.

The miserable condition of the engine had been worsened by its exposure of several years to the mercy of the weather, thus having heavily rusted through. To start he refurbishment of this engine in the Tuesday Club, we fetched it from Tampere in the boot of a Skoda Octavia.  

Our purpose is neither to repair the Continental engine into working condition nor to restore the airworthiness of Snoopy. To refurbish the engine, we will dismantle it to pieces as fully as possible, then after cleaning and fixing those, the engine will be re-assembled and attached to the nose of Snoopy.

All parts of this damaged Continental are not remaining, as some of them were destroyed in the crash. However, we hope to find or to get substitute parts for the missing ones later on. We also welcome any parts rejected in repairing and servicing Continental engines.

Dismantling of the engine was started outdoors at the Finnish Aviation Museum by detaching the badly damaged engine mount and the lower oil sump, which were still attached to the engine. At the hub of the propeller, the burnt propeller stem remained. After the nuts of the hub bolts were loosened, the propeller torso could be detached.

Next the remaining left-hand side exhaust pipe, spark plugs, both magnetos attached to the timing gear cover, the cover itself and the sprockets under it were removed. The lid of the oil pump under the timing gear cover was opened and the pump sprockets were taken out to be cleaned.

Photo by Esko Rossi.

Dismantling the engine was continued at the Museum’s restoration shop. The engine was fastened to a trestle, where the engine could be turned around its longitudinal axis, like in a barbeque. This greatly helped the handling of the engine. Now we detached the valve rods of the rocker arms and thereafter the rocker axles, after which the rocker arms came off the cylinder head. It became clear that the valves didn’t budge an inch. We tried to make them move and loosen them by dissolving with antirust agents.

Also the propeller hub was stuck firmly to the crankshaft. To dislodge the hub for cleaning, we applied various antirust and lubricant agents, but the propeller hub just wouldn’t budge. We gave some time for the antirust agent to work and finally managed to get the propeller hub out with a puller.

Only the cylinders remained in the engine block. We wanted to get them unfastened, too, to facilitate blasting their surfaces clean when separated. We were increasingly worried whether the pistons inside were rusted too tightly onto the walls for the cylinders to be taken loose. Well, we can at least give them a go, as they say, and that’s what we decided to do.

We turned the nuts on the mounting pins open and tried if the pistons would budge. No go. We then poured white spirit into the cylinders through the plug holes, to see if it would squeeze between the pistons and cylinder walls, and mobilize the stuck pistons enough to detach the cylinders. So far, we haven’t succeeded in this, “but we shall never surrender” to quote Sir Winston Churchill.

Photos by Lassi Karivalo except if otherwise mentioned.

Translation by Matti Liuskallio.

The Myrsky Group of Tuesday Club completes its job

Maanantai 23.9.2024 - Tuesday Club member

Suomeksi

The eleven-year project of the Myrsky Group, to restore the aircraft registered as MY-14 of the WW2 fighter VL Myrsky II, has been brought to its conclusion. The restoration project was started in the autumn of 2013. In concrete terms, the Myrsky Group of the Tuesday Club and the Finnish Air Force Museum shared responsibility of carrying out the restoration, the latter concentrating in restoring the fuselage.

Generally, we talk about the restoration of the Myrsky, but there is also good reason to call it renewed production, as most of the Myrsky with its mixed construction had to be entirely built anew, based on the original drawings of the aircraft. This is how the construction of, among others the wood-structured wing, the vertical and horizontal stabilizers, the rudder, and the aluminum NACA ring, wing root fairings, engine cowlings, and air ducts of the oil cooler were produced.

The largest single original part in the restored Myrsky is the fuselage framework of the MY-14. It defined to identify the project as restoration of the Myrsky MY-14. There are other original metal parts of Myrsky as well, but most of even them had to be manufactured.

The original plan was to transport those parts of the Myrsky that were built by the Tuesday Club at the Finnish Aviation Museum in Vantaa, to the Finnish Air Force Museum at Tikkakoski already in June 2024, to receive their surface painting. Some of the parts were sent as planned, but mostly the transport was delayed until the autumn, as everything wasn’t ready yet by June.

Photos by Lassi Karivalo.

The packing of the remaining parts of the Myrsky for transfer to Tikkakoski was started in August. The packaged parts were tied onto pallets that could then easily be moved by forklift onto the platform of the transport lorry. The wings were not packaged, but instead fixed onto wheeled transport frames that proved handy in moving around each heavy wing, weighing over 200 kilograms. Specific braces were tailored for the wings, to enable stacking them on top of each other on the lorry platform. This stacking procedure was tested in advance before the transport in the restoration workshop of the Finnish Aviation Museum, separating the wings and laying them on top of each other, like they would be travelling during the actual transit.

Photos by Lassi Karivalo

On Wednesday, 18 September, a lorry of the Defence Forces with its trailer arrived at the Finnish Aviation Museum to fetch the parts of the Myrsky to Tikkakoski. The loading of the parts began. Each wing was loaded (with ailerons, flaps, landing gear, wheels, and wheel well doors packed separately), parts of the tailplane (vertical and horizontal stabilizers and the respective rudder and elevators), the oil cooler (with air intake and exhaust air ducts), the aluminum wing root fairings, and a great number of small parts. Previously the NACA ring, the lower engine cowling, air duct and air horn had been already delivered to Tikkakoski.

After all the Myrsky parts had been loaded either on the platform or the trailer of the lorry, the journey to Tikkakoski commenced. After arrival at the destination, the freight was moved inside the FAF Museum.  

Even though the Myrsky project has now been completed for the part of the Tuesday Club, the whole restoration project is by no means over yet. At Tikkakoski, the parts of Myrsky with primer painting will be getting their surface paint of green / black camouflage pattern, national insignia, and the identification code of the aircraft. This task is already underway. Would one dare to say that the Myrsky MY-14 will be assembled on display at the FAF Museum still during this year, as there have been so many failed predictions?

The restoration project of Myrsky is one of the most extensive restorations ever in Finland, of aircraft used by the Finnish Air Force. The working hours used for the project speak for themselves. By mid-September 2004 the restoration of the Myrsky MY-14 during eleven years had taken working time as follows, with numbers rounded. Total work input: 40,000 hours. To this total, the Myrsky Group of the Tuesday Club had contributed 28,000 hrs. The share of the FAF Museum is 9,000 hrs. Outside the project, either paid or donated work amounts to 3,000 hrs. Based on the numbers, the Myrsky Group of the Tuesday Club has produced most, i.e. 70% of the restoration effort of the Myrsky.

However, there will be more working hours waiting for the Finnish Air Force Museum to accrue to the total amount at stake for the Myrsky restoration. Those will be coming from the surface painting of Myrsky, presently underway, as well as from the final assembly for display at the Finnish Air Force Museum.

Photos by Jouni Ripatti except if otherwise mentioned.

Translation by Hannu Mononen.

The Link Trainer wings ready to be delivered to the Karelian Aviation Museum

Maanantai 9.9.2024 - Tuesday Club member

Suomeksi

The Karelian Aviation Museum, situated in Lappeenranta, asked the Tuesday Club to restore the wings of a Link Trainer (LT) in their collection. Partly broken and wing covering torn the wings were brought to the Finnish Aviation Museum at the end of 2023 and the work could be started. The progress of the wing restoration has been followed in earlier Tuesday Club blogs.

Our aim was to complete the restoration work at the end of May, before closing the Tuesday Club’s spring season 2024 but the top coating of the wings was left unfinished. So the painting continued in August after the Club’s autumn season had started. Presently the wing paintings are concluded.

Left hand side photo: Kimmo Marttinen.

The wing covering fabric, which we had tightened to drum top tightness with NC-Speed nitro cellulose lacquer, was painted with Isotrol oil paint. The paint was tinted similar to the original beige tone (tint TVT Q609). The painting was executed with a paint brush and the Isotrol-paint had an excellent coverage from the first layer on. Furthermore, the paint formed an even and smooth surface, so a second application of paint was unnecessary. Someone at the Tuesday Club cut in saying: ”My word. It’s like factory work!”

When both wings had been painted, the earlier restored ailerons were assembled in them. It’s a bit peculiar that this Link Trainer has ailerons in the wings, but no mechanism to transact the joystick’s movements to the ailerons. There are Link Trainers with moving ailerons. There are also Link Trainers with only a piece of board instead of a canvas covered wing.

The aileron is fastened to the wing with two traditional hinges. During the restoration the screw holes had remained under the covering. The places of the hinges could be defined by photos, which were taken before restoration to define the status of the wings. The places of the hinges were marked on both wings with masking tape.

The ailerons were attached one by one to their own wings. Each hinge was placed on the marking tape on the aileron and the middle screw hole was marked on the tape. Traditional groove head screws were used. A screw hole was bored on the mark with a thin bit and the screw was screwed on. After this the marking tapes could be removed.

With both hinges had been fastened in the aileron with its middle screw, the aileron was placed in place beside the wing so that the other halves of the hinges were now resting against the wing. The place of the middle screw was marked on the wing, after which the middle screws were screwed on. The aileron was now fastened in the wing.

The next step was to check that the aileron was fastened in the right position. When that was verified, all the hinge screws were screwed to place. Installing the ailerons was now completed. The last phase in the restoration was to paint the brackets in the wing beige. These brackets are needed to fasten the wing to the Link Trainer fuselage.

The restoration of the wings was now completed and they were ready to be delivered to the Karelian Aviation Museum in Lappeenranta. The tail boom stabilizers of the Karelian Aviation Museum’s Mil Mi-8 (HS-4), which we had finished in the spring, will go with the same delivery with the Link Trainer’s wings.

Photos by Lassi Karivalo except if otherwise mentioned.

Translation by Matti Liuskallio.

Caravelle's seat covers repaired

Sunnuntai 11.8.2024 - Erja Reinikainen

Suomeksi

Caravelle two years ago. Some of it clearly belonged to the SE-DAF but there was also material from some former SAS Caravelle and probably from other types of aircraft as well. The material could be partly from the Transwede Caravelle 10BR (SE-DEC) which was damaged beyond repair in an unsuccessful take-off in Arlanda in January 1978.

In autumn 2023 we rummaged through the crates in the storage container at Turku airport. We found out that there were enough seat covers and other material for the 4-5 seat rows which were to be assembled in the front section of the cabin. The Caravelle seats could be fitted with original seat covers and seat belts. Original seat padding or cushion material has not been preserved so new ones will have to be made.

This blog describes how the old seat covers were repaired for use.

The dark green seat covers, made of some kind of wool mix fabric, consist of three parts:

• the cover of the actual seat part which is fastened to the bottom of the seat frame with four poppers (snap fasteners)
• the seatback “hood” which is pulled on the seatback frame and its padding, and fastened with Velcro tape on the backside of the seatback and by its lower edge on the seat pocket part
• the upholstery material for the seatback’s backside and the seat pocket which is fastened on the seat frame with screws by its upper corners, some glue and two hooks connected to the seat pocket, furthermore the lower edge of the seat pocket is fastened on the lower edge of the seatback hood with Velcro tape  

Further examination of the textile material showed that there were about 40 seat part covers, some of them broken and worn beyond repair. There were far less seatback hoods, about 25 of them. They are mainly rather worn and already patched. Seat pockets we have in large numbers, but many of them are dirty and several are broken. However, the situation looked good and there was useful material for covering about 25 seats.

The repairing of the seat covers was started with a washing test. The seat cover parts of one seat were washed in an ordinary household washing machine, in a 30°C gentle wash cycle, and dried. Comparing the washed parts to the unwashed ones proved that the fabric didn’t shrink. The wet fabric had a really odd smell, maybe it was due to decades of storage in the wooden box, or maybe it was some fire-retardant chemical from the 1960s… After the washing test the repair work commenced, the repaired seat covers would be washed later.

The first parts to be repaired were the actual seat parts. The typical damage included ripped seams, broken or missing poppers, round holes – probably caused by a cigarette fallen from a passenger or by the ash fallen from a cigarette. As patching material some non-fraying green cotton fabric was bought from Eurokangas, the colour proved to be very close to the original one. The patching fabric was washed before use. The holes and worn or frayed areas were patched by placing a piece of patching fabric under the area and stitch criss-cross over the hole area, using a household sewing machine. Poppers were moved from seat covers beyond repair to the ones in better condition but missing poppers. 

Then the seat cover hoods were repaired. The typical damage in them were ripped seams and threadbare areas in the lower parts of the hood where the seat belt and the seatback movement have rubbed the fabric. There are so few seatback hoods available that repairing the worst ones meant sewing new patches on old patches. The household sewing machine couldn’t handle the trickiest patches and help from a friend with an industrial sewing machine was needed.

The last item to be repaired were the seat pocket parts. At the time they have been removed from the seat frames without opening the screws on the top corners, so the corner pieces have been ripped off. Nearly all seat pocket parts needed their corners patched. The actual seat pocket is a pocket sewn on the fabric covering the backside of the seatback. There has been an elastic band at the top edge of the pocket, fastened on the seatback frame with small hooks. We don’t have any original elastic bands or hooks. Developing a new elastic band and hook system took some time. Eventually a small birdcage lock clips which fitted a 20 mm elastic band were found and the clip will be easy to fasten on the seatback frame. The downside of this solution is that it was quite arduous to slip the elastic through the seat pocket edge and sew the clips on the elastic band on 24 seats…

When all seat cover parts had been repaired, they were washed in 30°C gentle wash cycle. The ugly stains (maybe coffee?) on the seat pockets came off quite nicely even in the household washing machine. Weather permitting, the washed textiles were hung outside to dry to get rid of the odd smell.

There are plenty of turquoise seat belts in our container and we could select the ones in best condition to be reused. A pressure washer was used for washing the seat belts, then they were hung out to dry. The fastening mechanism on both ends of each seat belt needs to be checked and oiled. Each belt has a label with the manufacturing or installation date, the belts have been labelled in the 1960s and 1970s.

The repaired and washed seat covers and seat belts are now waiting for the seat frames to be repaired and for the new padding material to arrive.

Photos by Erja Reinikainen.

Assembling the Myrsky wing root fairings and the oil cooler

Maanantai 15.7.2024 - Tuesday Club member

Suomeksi

Apart from the Myrsky-project other activities of the Tuesday Club are on hold for the summer break. So the parts of the OH-XEA “Ressu”, Caudron C.59 (CA-50), Valmet Tuuli III (TL-1) and the Link Trainer, heaped in the former Aviation Museum coffee room, can wait for the work to continue halfway through August, when the autumn season 2024 for the Tuesday Club will commence.

The project members of the Myrsky restoration team at the Tuesday Club have toiled “day in and day out” to finish and assemble the wing root fairings covering the wing/fuselage seam and the oil cooler, with its intake and exhaust air horns. Both these projects have taken more time than planned, so the Myrsky II (MY-14) roll-out, planned for the beginning of August, will be delayed. The summer holiday season both at the Finnish Air Force Museum and at Patria industries have affected in the delay.

Oval-shaped openings and a flapped hatch were made to the lower surface of both the right and left-hand side wing root fairings. The narrow oval openings are for cooling the wing root fairings, which for their part cool down the engine oil cooler, sheltered by the fairings. The edges of the openings cut to the aluminium plate were strengthened with a 1 mm thick aluminium strip.  The strips were fastened with rivets.

The wing root fairing edges were likewise strengthened with aluminium strips on both fairings. That way the fairings stay better in form and are easier to handle when they are more rigid. The strips were riveted to the wing root fairings with countersunk rivets.
In addition to the abovementioned ventilation openings, an opening was cut to the right-hand side wing root fairing, for the horn for the exhaust air from the oil cooler. The exhaust air will be conducted through the opening in the fairing onto the lower surface of the wing. The edges of the opening for the exhaust air horn were strengthened with 1 mm thick aluminium strips.

Photo by Heikki Kaakinen

When the openings in the right-hand side wing root fairing were ready, the fairing was fitted in place. After that, the end of the horn for the exhaust air could be pushed into the opening in the fairing and fasten the other end of the horn to the oil cooler. It was noted that the exhaust air horn fitted its opening just like it should.

Left hand side photo by photo archive of Finnish Aviation Museum.

Next in turn was the making of the cover for the space for the mouthpiece of the intake air horn. The mouthpiece of the horn is situated in the leading edge of the wing in an area limited by two ribs and the front spar. Cooling air for the oil cooler is taken through an opening in the wing’s leading edge. The horn for the oil cooler intake air is for the most part located under the left-hand side wing root fairing, but the mouthpiece of the intake air horn reaches outside the fairing edge.

Photos by Heikki Kaakinen.

When the intake air horn for the oil cooler and the left-hand side wing root fairing had been installed once again, we checked once more that the air intake horn’s mouthpiece was exactly flush with the wing’s leading edge. Now we could start to make the cover for the space for the mouthpiece of the air intake horn. The space will be covered with a shield made of aluminium sheet, with an opening for the air intake horn. The shield will be fastened to the wing ribs and the edge of the front spar.

The blank for the shield was cut from 1 mm thick aluminium sheet. The blank was bent to match the leading edge shape. After that an opening for the air intake horn for the oil cooler was made. The half-ready shield was fitted to its place. It was observed to sit well. The edges of the opening of the shield were bent inwards by forcing.

Photo by Jorma Laakkonen.

The aluminium shield covering the mouth of the oil cooler intake air horn will be fastened at its edges with screws and flange nuts to the wing ribs and the wing spar. On the fairing side the right-hand edge of the shield remains in between the stem fairing and the metal wing rib, i.e. it will be fastened to its place simultaneously with the edge of wing root fairing. Holes for screws were drilled at the edges of the shield. The holes were strengthened with “crickets” or brass strengthening rings.

Photo by Heikki Kaakinen.

The shield was now ready to be test-fitted together with the left-hand side wing root fairing. So the shield was screwed at its edges with a few screws to the leading edge rib and the front spar’s upper and lower edges. After this the left-hand side wing root fairing, next to the oil cooler, was fitted to place. The outer edge of the fairing curved snugly over the air intake horn’s mouthpiece shield’s edge. Assembling the wing root fairing and the shield needs only some fine adjustment.

When the fittings of the oil cooler air intake and exhaust air horns, wing root fairings and the air intake horn mouthpiece shield are ready, the aluminium parts that haven’t been chromated will be taken to Patria Industries for yellow chromating. The chromating will take place at the beginning of August.

By now it’s clear that the preplanned roll-out event of the MY-14 Myrsky fighter will be postponed. But, as they say, it’s worth while waiting for something good.

Photos by Lassi Karivalo except if otherwise mentioned.

Translation by Matti Liuskallio.

A busy weekend at Caravelle at Turku airport during July 13th and 14th

Maanantai 15.7.2024 - Ismo Matinlauri

Suomeksi

This weekend was the busiest we have had so far this year at our Caravelle. In this blog you will find some photos from the successful events.

Saturday, July 13th

On Saturday there was a display of French vintage car technology beside the Caravelle.

Club Renault de Finlande is celebrating its 40th anniversary this year. They started their Finland Tour from Turku airport on July 13th. For Renault 2024 is a year of celebration as well, the company was established 125 years ago.

Below some photos from the sunny Club Renault de Finlande event. The weather conditions were favourable, and the temperature climbed to +26 degrees Centigrade.

There was a nice collection of vintage Renaults on display.

The day was successful also for Caravelle as we had well over 50 visitors.

Sunday, July 14th

On Sunday morning it was rainy in Turku and the temperature was much lower than on Saturday, only +18 degrees Centigrade. Despite the drizzle, we celebrated the National Day of France and hoisted the flag appropriately. In the staff room “Café Caravelle” there were naturally fresh croissants available for our volunteers.

There were less visitors than on the previous day, probably due to the weather. However, there were more than a hundred visitors during the weekend, and we can be very satisfied with these summer events.

Next week we will have the main effort of the summer as Caravelle will be open to the public during the Tall Ships Race event in Turku. The aircraft is open daily from 10 am to 3 pm from Thursday to Sunday, July 18th – July 21st.

If you are in the Turku area next week, come and visit us at the airport!

Photos by Ismo Matinlauri

Translation by Erja Reinikainen.

Caravelle's holiday season

Lauantai 6.7.2024 - Ismo Matinlauri

Suomeksi

The Caravelle Turku team volunteers finished their spring season at the end of June. The team members started their well-earned holiday at their cottages, travelling or being active in other hobbies. In the beginning of August they will return to Caravelle restoration work.

During the spring season the Turku team and the assisting technical team totalled almost 850 hours of voluntary work. Some news about the most recent work in June are shown below. Furthermore, the polishing of the lower part of the aircraft’s fuselage was continued whenever weather permitted.

The office

Ramirent Oy (the equipment rental company) donated us two modular containers which were joined and assembled beside the Caravelle. Now we have a combined office and shop on site.

A power supply was installed, and the office was furnished. Everything is ready inside and outside and we can use our new space during the summer season. A housewarming event will be arranged in August.  

Also our unofficial “Café Caravelle” (i.e. the Turku voluteers’ coffee break facility) was moved from the aircraft cabin into the new office. Now there is more space for the future interior work, and it is also easier to move in the cabin as there is less material and furniture.

The passenger door and cabin partitions

The left-hand side passenger door’s complicated opening and counterbalancing mechanism was repaired during the spring. This was quite an effort and a series of four blogs was written about it earlier. The repaired door mechanism works fine, and the passenger door is open during the visiting hours.

The partitions in the front part of the cabin are fitted into place in the two photos. The passenger door is open to confirm the correct location of the partitions so that the door opening mechanism is not disturbed. The partitions will be resurfaced in August, using material which resembles the original one, and then assembled into place.

Electrical installations

The electrical installation work is almost completed. Power outlets are already in place and connected. The wiring for lighting is almost ready, too. In August when the work continues, LED lighting will be installed on the flight deck and in the toilets and galley area in the rear section.

A LED-strip will be installed in line with the upper edge of the cabin overhead hat rack. The photo shows its wiring, waiting for the ceiling surface material installation. After that the LED-strip mounting can be assembled.

The last photo shows the white main distribution board which will be installed into the former equipment rack behind the flight deck, on the left-hand side. Wiring from the distribution board is located under the cabin floor. The wiring was being installed when the photo was taken.

Before going on holiday we collected all tools and tidied up inside the aircraft for the visitors’ events. The Caravelle will be open to the public on several occasions in July. Our volunteers will be on site to introduce the aircraft and its history.

Photos by Ismo Matinlauri.

Translation by Erja Reinikainen.

Caravelle's passenger door mechanism is repaired - Part 4

Maanantai 27.5.2024 - Erja Reinikainen ja Martti Saarinen

Suomeksi

The reparation procedure of the left-hand side passenger door’s complicated opening and counterbalancing system has been described in the previous blogs and the story is completed in this one.

During our previous reparation visit the door was already functioning in the desired way but after a long working day the last adjustments and final inspection were not done. Therefore the door could not be taken into use yet. In the week before our latest visit to Turku we asked the Turku team to check whether the bungee ropes are still tight when the door is closed. The reply was reassuring, they are tight all right. This meant that nothing had failed or broken while the counterbalancing system had been carrying a full load for a week while the door remained closed.

After arriving we lifted the cabin floorboards and checked the bungee ropes in the side tunnel under the floor. The ropes were still tight, so everything was ok. The polishing team was working outside, polishing the lower section of the passenger door and we had to wait for a while before we could open the door. It could be opened without problems.

Photo by Ismo Matinlauri.

When the door was open and in its highest position, we could see that the bungee ropes had slackened a little. This we had expected to happen. There is a convenient adjustment at the far end of the each bungee cord attachment cable: the fastener pin is moved on the connecting piece into the hole where the desired tightness of the bungee rope is achieved. The adjustment was done in a couple of minutes and the door operation was tested again. Everything worked fine. After this the last installations were done, and the final inspection was completed.

The Turku team members were given user training on how to operate the door. Now it can be used safely and there is no need to go back and forth through the small and low service door. The passenger door was open for the visitors during the weekend opening hours on May 25th – 26th.

Meanwhile, work on the flight deck was continued to have the side windows replaced. The small triangular windows had already been replaced and now the large rear windows were under work. The windows are the emergency exits for the flight deck crew, so they are easy to remove by opening the locking levers and lifting the window away.

However, this was easier said than done after the aircraft had been standing outside for almost fifty years. A lot of gun oil and some patience were needed to open the locking mechanisms but eventually they could be opened. Installing the new window on the left-hand side went smoothly but the right-hand side was more difficult. Some machining was needed and two assistants helping before the window was in its place.

Photos by Martti Saarinen except if otherwise mentioned.

Translation by Erja Reinikainen.

The right-hand side wingtip of Caravelle III "Bluebird" is delivered to Turku

Sunnuntai 26.5.2024 - Tuesday Club member

Suomeksi

The Caravelle III "Bluebird" (OH-LEA), on display in Turku, has until now been without the wing tip piece of its right-hand side wing. For about a year, the wingtip has been under repair and parts of it have been rebuilt at the Tuesday Club, working at Finnish Aviation Museum. The leading edge of the wingtip had been destroyed while the Caravelle, in SAS colours at the time and carrying registration SE-DAF, stood by the edge of Arlanda airport for decades. Probably some airport vehicle had bumped into the aircraft.

The repair work of the right-hand wingtip section was completed at the Tuesday Club, but it wasn’t taken to Turku until now. The wingtip was transported from Finnish Aviation Museum in Vantaa to Turku airport, to be assembled on “Bluebird’s” wing. The wingtip section is too large to be transported in an ordinary passenger car. It was packed properly and loaded on the Aviation Museum yard on a trailer. The journey towards Turku could begin.

The vehicle was welcomed at Turku airport by the Caravelle Turku restoration team. The team unloaded the wingtip from the trailer and carried it under Caravelle’s right-hand side wing to wait for assembly.

Right-hand photo by Reijo Siirtola.

Now all Caravelle work allocated to the Tuesday Club have been completed. The work included repairing the nose bulkhead edge and the damaged radome, refurbishing and painting the wall panels of the flight deck and the corridor leading to the flight deck, repairing the glare shield above the flight deck instrument panel, building the frame for the navigation light on the right-hand wingtip and preparing the navigation light globes by 3D-printing.

Photo by Ismo Matinlauri.

Furthermore, in 2022 we built stands for supporting the Caravelle’s fuselage and wings during the transportation from Arlanda to the former shipyard hall in the Pansio harbour area in Turku. We also restored the Caravelle III towbar, brought from Arlanda, which was in poor condition. The towbar is already in place, fastened on “Bluebird’s” nose wheel.

Photos by Lassi Karivalo except if otherwise mentioned.

Translation by Erja Reinikainen.

Caravelle's passenger door mechanism is repaired - Part 3

Tiistai 14.5.2024 - Erja Reinikainen ja Martti Saarinen

Suomeksi

The reparation procedure of the left-hand side passenger door’s complicated opening and counterbalancing system has been described in the previous blogs and the story continues in

During the previous reparation effort the door could be opened with a manual winch, but the bungee ropes which were tested, were too weak to be used for opening and counterbalancing the door. There were also problems with the new roller chain and the door seemed to be slightly tilted. The technical team thought the problems might be caused by wrong adjustment of the cables or bungee ropes, or due to some part being bent in the process. Stronger bungee ropes were ordered from the US, and when they arrived it was time to try again to make the door work.

The attachment pieces at the door end of the new roller chain had been modified a little and this seemed to help to correct the door position. It now moved down without tilting on one side. Terminals made of copper tube had been prepared for the two new bungee ropes in the lifting mechanism, to fasten the bungee ropes to the sliding carriage and to the door lifting cables. For establishing the correct length of the bungee ropes, temporary fasteners were prepared for the rear end of the ropes to fasten them to the end cable of the bungee track. In the first phase the blue bungee rope in the middle was not changed, it remained as it had been in the previous testing.

 

The day was spent adjusting the length of the bungee ropes and cables, testing the door movement every now and then, and adjusting some detail once again. Some changes were also made on the bungee rope track. Eventually the door could be opened smoothly and rather lightly but closing it fully from its down position still required a fair bit of force.

At this point terminals from copper tube were made also for the rear end of the two outer bungee ropes and the temporary fasteners were removed. The third bungee rope in the middle was replaced with a sturdier one and terminals were made for its ends. With this arrangement the door could be moved with less force but closing it fully was still difficult. After some additional adjustments the door was functioning as it should, but it was not taken into operation yet. The technical team had been working for full eight hours at this point, so it was time to call it a day. Next time the installation will be completed, and the adjustments will be checked after the bungee ropes have been under tension for a longer period when the door has been shut.

During the day there were naturally also other activities going on: The assembly of the office and visitor centre (which is a prefabricated reusable and movable small building) was continued and the space was prepared for the opening hours on the coming weekend. Tables and sales items were moved from the aircraft into the new building. The broken sealing strip on the passenger door was replaced with a new one.

On the flight deck there was a time-consuming battle to open the emergency exit windows’ locking mechanism which had rusted solid. Among the material brought from Arlanda in 2022 there are two windows for both sides of the flight deck. They are in better condition than the existing ones and they will used to replace the old ones. Eventually the rust on the mechanism began to yield and the locking of the windows can be opened.

The planning of the new padding for the passenger seats was continued. A workable solution is beginning to take shape.

Photos by Erja Reinikainen.

Caudron C.59 advanced trainer; covering of the horizontal stabilizer

Tiistai 14.5.2024 - Tuesday Club member

Suomeksi

Caudron C.59 was an advanced trainer used by the Finnish Air Force in the 1920s. The restoration of the individual aircraft CA-50 was commenced at the Tuesday Club in 2019. The work has advanced in stages. After the Finnish Aviation Museum acquired from abroad cotton fabric designated to covering aircraft, we could start covering the horizontal stabilizer of the Caudron, which had been waiting for some time. We had earlier refurbished the Caudron’s horizontal stabilizer, which had been in very poor condition, by taking it apart and reassembling it for covering.

Prior to the covering, it was decided to lacquer with nitro cellulose lacquer the fabric strip covering, wound around the leading edge of the stabilizer. It was made of 50 mm wide linen band according to the original. By lacquering the band covering, the gluing of the covering fabric will be enhanced on the surface of the leading edge of the stabilizer.

Photo by Jukka Köresaar.

The linen band covering wound on the leading edge of the horizontal stabilizer was lacquered with 75% nitrocellulose lacquer. As lacquer we used NC Speed nitrocellulose lacquer, and it was tinted red with iron oxide powder. After the lacquer had dried, the edges of the linen band had, as we expected, risen as well as the fabric fuzz. So the band covering was sanded smooth, and another layer of lacquer was applied. Even after the re-lacquering, the leading edge band was uneven and the band had to be sanded once more, after which it was lacquered with 100% nitrocellulose lacquer. So the linen band wound around the leading edge had been smoothed, and we could start covering the horizontal stabilizer.

The width of the horizontal stabilizer is 60 cm and its length 120 cm, so a 130 cm wide piece was cut from the 140 cm wide cotton fabric. This way the fabric has enough working allowance to work both in length and width way. The fabric was wound around the stabilizer, which was laid the table, so that the lapels of the fabric reached past the horizontal stabilizer’s trailing edge. We meant to make a bag out of the fabric, which would be open at the trailing edge.

To achieve this, at both ends of the stabilizer the lapels were joined with pins. The lapels were then sewn together with a sewing machine, along the line of the pins. So the fabric was formed to be a bag, open at the trailing edge. When the ends had been sewn, the fabric was turned inside out, leaving the sewing seams of the lapels inside the fabric bag.

The fabric bag, open at the trailing edge, was drawn on the horizonal stabilizer. The sewing of the fabric was very successful, because the fabric bag had become tight, or rather “skin-tight” on the horizontal stabilizer. Now it was time to sew together the still open trailing edge fabric lapels. For the sewing extra parts of the lapels were cut off, so that the lapels met at the outer edge of the trailing edge batten.

To keep the lapels of the fabric in place when they were sewn together, the fabric was fastened with staples from a stapler at the side of the trailing edge batten. The lapels of the fabric were sewn together with a thin double yarn cotton thread. As a needle we used a curved needle, which was handy for this kind of sewing.

Photo by Antti Laukkanen.

The sewing of the covering fabric lapels was done so that the seam formed a continuous serrated shape. When the lapels had been sewn, the covering fabric formed a closed bag over the horizontal stabilizer.

Photo by Antti Laukkanen.

The next phase in the work was the water-tightening of the fabric. The stabilizer covering fabric was soaked with boiled, but cooled water, and was left to dry. With water-tightening, the fabric is pre-tightened, because when dried the covering fabric has already tightened a few percent on the stabilizer.

Photo by Antti Laukkanen.

The proper tightening of the covering fabric to resemble a drum head, will be made with nitrocellulose lacquer.  Before tightening the covering the fabric needs to be sewn on the stabilizer ribs. The sewing will be done by following the original 1920s Caudron stabilizer sewing method. This way of sewing was documented, when the decayed covering fabric was stripped off the Caudron’s stabilizer. According to that, the covering fabric was sewn onto the fabric strips, which were fastened to the stabilizer ribs, with tacking interval of about 3 cm. The fabric strip was for its part tied to the rib’s surface with an edging ribbon. We had done similarly, when refurbishing the stabilizer.

The places of the stitches were marked at each rib on the surface of the covering fabric, using a thin template made of plywood. The stitching places of the sewing needle were marked on the fabric surface with a thin felt pen, through the template holes. Using a curved needle and double yarn thin sewing thread, the covering fabric was sewn stitch by stitch to the edging ribbons that ran along the ribs. A regular space between the stitches made it possible that the needle occasionally pierced the edging ribbon which tied the fabric strip to the rib. When the sewing had been done, the staples could be removed from the fabric surface.

The covering fabric was now sewn to the horizontal stabilizers’ ribs, both on the upper and the bottom surface, so it’s time to move on the next phase of the covering. There the horizontal stabilizer’s covering fabric will be tightened to drum head tightness with nitrocellulose lacquer. As lacquer we use NC Speed nitro cellulose lacquer. Applying the lacquer is started with 25 % thinned lacquer, and from there in stages to the full 100% nitrocellulose lacquer.

Photos by Lassi Karivalo except if otherwise mentioned.

Translation by Matti Liuskallio.

Covering of Ressu's (Snoopy) rudder

Maanantai 6.5.2024 - Tuesday Club member

Suomeksi

When the preliminary tasks concerning the covering of the experimental aircraft Hietanen OH-XEA rudder had been done, the proper covering could be commenced. The rudder covering is done with cotton fabric meant for covering aircraft. The covering will be done the same way it had originally been done in the 1960s.

The covering got started by setting the metal-framed rudder on the fabric, which was spread on the table. The edge of the fabric was wrapped around the right-hand side metal tube of the leading edge and sewed onto it.  The sewing was done with thin cotton thread, using a suitable curved or hooked needle.

After the fabric had been sewn to the leading edge right-hand tube, the rudder was turned over on the table, so that the metal frame of the rudder was left under the fabric. The fabric that was attached to the right-hand leading edge, was drawn over the leading edge and left-hand side to the trailing edge the of the rudder, where the lapel of the fabric was left hanging over the table edge.

A metal bar was attached to the hem of the fabric hanging over the table edge. With the aid of the bar the fabric, resting on the left-hand side of the rudder, was tightened. At the top and bottom edges of the rudder the lapels of the fabric were tightened with small clamps to the edge of the table. When the fabric was tightened this way, the water tightening of the fabric was started. The fabric was soaked through with boiled water. When drying, the fabric shrinks a little. The proper tightening of the covering fabric will be done after the water tightening with nitrocellulose lacquer.

The tightening lacquering of aircraft covering fabrics is carried out in a process with several phases. The tightening lacquering is started with a 25 % thinned nitrocellulose lacquer. From that the process continues with intermittent sanding to 50, 75,100 -% nitro lacquer. After each phase the fabric is sanded free of the fuzz brought to the surface by the lacquer. From phase to phase the covering fabric will shrink more and more. The end result is a covering fabric tight as a drum head. The sufficient degree of tightening is easy to verify by tapping the surface. It’s customary to pigment or colour red the lacquer with iron oxide powder. This will help to recognize which area has been dealt with the lacquer and which not.

When the water-soaked fabric on the left-hand side of Ressu’s rudder had dried, 25 % thinned NC-Speed nitrocellulose lacquer was applied on the surface of the fabric. As a thinner NC-Speeds’s own Thinner-8 was used. The lacquer was tinted red with red iron oxide powder. After the lacquer had dried, the weights were detached and the rudder was turned around, after which the unlacquered side of covering fabric was drawn tightly under the right-hand side of the rudder. The lapel of the fabric was sewn to the leading edge of the right-hand side metal tube, i.e. the same, where the lapel of the fabric had been sewn in the first place. The covering fabric was now around the rudder like a bag.

Now the right-hand side fabric of the rudder in its turn was water-soaked. After that this side, too, was lacquered with 25% NC-Speed tightening lacquer. After the lacquer had been dried, the rudder’s lower edge, triangular shaped in cross section, was covered by sewing the lapels of the fabric onto the tubes in the rudder’s lower edge.

The tightening of the covering fabric continued with applying a second layer of 25 % lacquer on the rudder surfaces. Because the fabric didn’t start to tighten in the manner we had hoped, the rudder was lacquered a third time over with 25% lacquer. From this point on we advanced in stages to three times applied 50% and twice applied 75% NC Speed lacquering. In this manner a sufficient level of tightness was achieved, so that the fabric strips protecting the stiches of the covering fabric at the edges of the rudder can be fastened. The protecting strips will be glued to the leading, upper, and bottom edges of the rudder. No strip will be needed at the trailing edge because there’s no seam in the fabric there. Of course we could glue a strip there, too, because it would make it more resilient.

The protective strips were cut off the same covering fabric with which the rudder was covered.

The cutting was done with serrated zig-zag scissors. The serrated edge of the protective strip will stick better to its base, i.e. the lacquered surface of the covering fabric compared to the straight edge.

The protective strips were glued to the rudder with 75% nitrocellulose lacquer. First the area of the protective strip was lacquered, after which the strip was pressed onto the wet lacquer. The strip was applied with lacquer so that it became thoroughly soaked with lacquer. The strip was pressed against is base and brushing away air pockets or bubbles from under the strip. At the same time it was made certain that the serrated edges were tightly glued to the surface of the covering fabric.

After the strips had dried, their surfaces were sanded smooth paying attention especially to the serrated edges. The lacquering and sanding were repeated three times, after which the protective strips and especially their serrated edges were worked so smooth, that feeling with your finger gave you no sensation of the strip edge on the surface of the covering fabric.

After fastening the protective strips, the whole rudder was lacquered once with 100% nitrocellulose NC Speed lacquer. The covering fabric of the rudder had now reached the stage where it was as tight as a drum head and thus ready for painting. According to Ressu’s original colour scheme it will be light bluish grey.

Photos by Lassi Karivalo.

Translation by Matti Liuskallio.

Caravelle right-hand wingtip is finalized with the navigation light globe

Lauantai 27.4.2024 - Tuesday Club member

Suomeksi

When the new leading edge had been built to replace the destroyed right-hand side wingtip leading edge on the Caravelle III (OH-LEA Bluebird), we could begin the installation of the navigation light globe into its place on the leading edge.

We don’t have the original navigation light globe because it has been destroyed together with the wingtip. We could not find a globe as a spare part either, so we had to make one. We chose to do this by 3D-printing. We used the partly broken navigation light globe from the left wing as a model. A new globe was printed for the right wing and also for the left wing navigation light.

The new navigation light globe was installed on the OH-LEA Bluebird’s left-hand wing earlier in the summer of 2023. The right- hand wing, however, had to wait until March 2024 for its new globe to be put already in early into place after the new leading edge of the destroyed wingtip had been finished.

The 3D-printed navigation light globe is made of stiff plastic, and in the beginning it didn’t fit properly into place. We heated the globe with a hot air blower so that it could be moulded to fit into its mounting on the wingtip. The globe was fastened tentatively on the edges of the mounting with a couple of screws. This was necessary for holding the globe in place while making the fastening frame. The globe is fastened on the aluminium edge of its mounting with a frame. The frame has holes for screws, and it presses tightly against the sides of the globe, and the screws in the frame holes are tightened through the globe edge into the aluminium edge underneath.

Diverging from the original solution, we decided to make the fastening frame for the globe from two parts. This made it easier to build the frame. Nevertheless, the frame we made will cover the most part of the navigation globe edge. A connecting piece will be needed on the top of the globe to connect the ends of the frame.

When the globe had been fastened with a couple of screws, broad paper tape was fastened on its edge. The shape of the globe frame was drawn on the tape. Based on the drawn line, a model for the frame was made of cardboard. The model was taped on a 1 mm thick aluminium sheet, which had already been pre-cut into the frame shape. After this we began to modify the sheet with a cutter to match the shape of the cardboard model.

The aluminium frame was test-fitted into place and modified several times. Gradually the frame reached its final shape and it rested against the lower edge of the globe as §planned. When the desired shape had been reached, the blue plastic film which had protected the aluminium surface was removed from the frame.

A strip of paper tape was fastened on the surface of the finalized fastening frame for marking the location of the fastening screws at regular intervals with a pencil. Holes for the fastening screws were drilled at the marked locations, then the screws were fastened one by one. This made the navigation light globe press into its place between the fastening frame and the edge of the globe mounting. Now the navigation light globe on the right-hand side wingtip was in place.   

The last phase was to make the 5 cm connecting piece between the fastening frame ends on the top of the navigation light globe. First a cardboard model was made of the connecting piece. The connecting piece was cut and moulded from aluminium sheet, following the model. When the blue plastic covering had been removed from its surface, the connecting piece was fastened between the fastening frame ends, using two screws with washers. Finally the screws were tightened.

Under the globe, out of sight, is the socket for the navigation light bulb and its green glass globe. The socket was lathed from aluminium and installed into place at the Tuesday Club. The Caravelle’s right-hand side wingtip is ready for housing a powered navigation light, if there is need for it at some point.    

Now the Caravelle Bluebird’s right-hand side wingtip had been completed. Re-constructing the destroyed leading edge took a whole year. The wingtip can be delivered to Turku to be assembled on the Caravelle Bluebird, which is on display near the passenger terminal at Turku airport.

Photos by Lassi Karivalo.

Translation by Erja Reinikainen.

Caravelle's passenger door mechanism is repaired - Part 2

Torstai 25.4.2024 - Erja Reinikainen ja Martti Saarinen

Suomeksi

Until now access to the Caravelle’s cabin has been through the small right-hand side service door and aft stairway. The passenger door operating mechanism has been damaged, and the door can’t be used before the mechanism is repaired. This blog describes the first phase of the passenger door repairs.

When the passenger door is opened, it moves first straight inwards and then it is manually lifted along its rails up to the cabin ceiling. The door weighs 53 kilos, so opening and closing is assisted with a counterbalancing system. The system consists of roller chains, steel cables and three bungee cords (rubber ropes), several metres long and located under the cabin floor. There are no spare parts available for this system anymore, so the new parts have been designed and made by the technical team.

On its visit to Turku on April 12th, the technical team started the door mechanism repair work. The first phase was to install the new roller chains into the door rails (the broken chains had already been removed). The new roller chain is slightly different from the original one and some parts for it were made by order in a laser cutting company, and others ordered from abroad.

When the two roller chains were in their rails, their lower ends were fastened to the brackets on the passenger door and their upper ends to the counterbalancing cables. The roller chains and cables run through the door rails and down to the guides, which are located on the sides of the right-hand side service door. There are 4 guides on each side of the door.

Under the cabin floor, in the side tunnel of the baggage compartment, the cables are connected to the bungee cords on a sliding carriage. The sliding carriage and its stops allow the bungee cords to operate in sequence, as the need for counterbalancing force depends on the position of the door. When closing the door, in the beginning the strength of one bungee rope is sufficient for the required counterbalancing. When the door moves downwards on the rails and is reaching its vertical position, the need for counterbalancing increases. This is when the two other bungee cords join in. The mechanism is complicated and not very reliable. When the Caravelle was in operation, the system needed regular repair and maintenance. The original bungee ropes have become brittle and can’t be used. The technical team is still looking for suitable material to replace the original ropes as the bungee ropes in the regular hardware store are too soft and slack for the purpose.

At this point the roller chain and the door function were tested without the bungee ropes by fastening the cables and the sliding carriage to a manual winch.

It was not that simple to operate the winch in the cramped space under the floor. The lifting force was measured with the digital scales connected to the winch. The original bungee ropes and their supporting rollers can be seen on the upper right corner of the picture.

The test arrangement worked: using the winch the passenger door could be opened, but not fully. At this point the door was secured with a couple or car tyres in the doorway.

The problem appeared to be the roller chain and cable guides, located on the sides of the service door: the new roller chain didn’t move smoothly through the guides. After some discussion the team decided to disassemble and adjust the guides. As a test, the upper guide was disassembled and cleaned, and installed back into place a little bit differently. This helped to solve the problem, so the other guides will be disassembled before the next visit of the technical team when the door mechanism repair will continue.

During the day there was also other activity in the Caravelle: three new instruments were installed into the instrument panel on the flight deck. It looks quite good already but there will be some more additions later.

The cabin curtains were unfastened from their popper slides to have them out of the way when the interior work begins. Fortunately the curtains are mainly in quite good condition, but dirty. They will be washed and ironed before putting them back. This won’t be done before the interior work has been completed.

Work was going on outside, too: the SAS prints were removed from the aft stairway before repainting. The best work method has proved to be to heat the painted area first with a blower and the scrape the paint off.

Photos by Erja Reinikainen.

The Ressu (Snoopy) rudder covering preliminary work assignments

Sunnuntai 21.4.2024 - Tuesday Club member

Suomeksi

The IMY Tuesday club has continued its work with the Snoopy (Ressu).

Planned and built by the Hietanen Brothers from Turku, the mixed structure experimental aircraft Ressu from the 1960s is next in line for the rudder’s canvas covered steel tube structure to be restored.

For the restoration the rudder was detached from the fuselage. The fabric covering was in a fragile shape, and the paint finish of the canvas badly crackeled. On the left-hand side the covering is fairly intact, but on the right-hand side a large piece of covering is missing on the lower edge. From this unexpected opening it could be seen that the covering canvas had been sewn onto the rudder frame outer tubes only, but not onto the cross tubes. The outer ring metal tubes had been covered with 20 mm wide cotton edging ribbon, by winding it the tightly along the tube.  This was a common way to avoid the covering fabric to be attached to form a direct contact with metal. The fabric, that was sewn to the metal structure, had been tightened drum tight with nitrocellulose lacquer, after which the surface had received a light blue coat of paint. Finally the rudder had been treated with red speed stripes, a black number 2 and a bird figure.

Because the Ressu’s rudder covering fabric was in a bad shape and partly broken, we decided to cover it completely anew, complying the old manner of doing it, however. The old covering fabric had to be detached from the steel frame of the rudder by cutting it off with a knife, because the fabric had glued itself tightly to the edging ribbons around the tubes. After detaching the covering fabric, the edge ribbons around the metal tubes were also removed.

The red stripes of the rudder’s covering fabric and the left-hand side black number two and the right-hand side black bird were copied on transparent rice paper. After that the bird and the number were transferred onto sturdy cardboard to wait for the final transfer of these symbols onto black contact plastic, and their fixing onto the surface of the new covering fabric.

The work with the rudder’s metal structure was continued with doing away with the rust on the tube surfaces. Luckily the tubes weren’t badly rusted or corroded. The rust was sanded off with sanding paper, however, so that the tubes weren’t ground to pure metal. The transparent Isotrol-lacquer can be applied as primer even though the surface is still a bit rusty. The shielding cover of the Isotrol- lacquer will stop the rusting process. During the sanding it had been noticed that the rudder had originally been painted red. The paint had most probably been the red Ferrex, used widely in the 1960s to stop rusting.

The rudder frame structure was primed thinly with the transparent Isotrol -lacquer. Owing to the lacquer, the tube surfaces came out beautifully clear and the red paint applied on the surfaces rose up even more gloriously. After a light buffing, a layer of red Isotol paint was applied on the bright Isotrol lacquer, emulating the original red surface paint.

When the rudder frame had dried, we started to cover the steel tubes by winding 20 mm wide cotton edging ribbon around the steel tubes. Thus we’ll prevent, according to the original concept, the covering fabric being in direct contact with the surface of the steel tubes. By hurrying slowly we managed to wrap the cotton ribbon around the outer tubes of the frame. Ressu’s rudder in now ready to begin the fabric covering proper.

Photos by Lassi Karivalo.

Translation by Matti Liuskallio.