Status of Caudron C.59 (CA-50) after 93 years of storage

Tiistai 16.11.2021 - Tuesday Club member

Suomeksi

With the marking CA-50 flown fighter trainer Caudron C.59 was removed from service in the Finnish Air Force in December 1928. The aircraft was stored in Santahamina to wait for restoration. In 1948 CA-50 was transferred to the hangar of Vesivehmaa airport together with many other written off  Air Force types.

The storage hall like hangar developed into the Päijänne-Tavastia Aviation Museum at Vesivehmaa, when a civilian organization called the Lahti Airlift took charge of it as a museum in 2006. About twenty aircraft, all of them in poor condition have been removed to be restored. Most of them are on display in Finnish aviation Museums and elsewhere, too. Of the aircraft restored by the Tuesday club the I.V.L D. 26 Haukka I and I.V.L K .1 Kurki have been returned back to the Päijänne-Tavastia Aviation Museum.

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At Vesivehmaa only the fuselage of the C.59 CA-50 has been on display. It lacks the Hispano Suiza-engine. The wings were stored at first in the nearby former Brewster maintenance space, afterwards in a sea container beside the hall. The Caudron’s lower wings and parts of the tail assembly have been under restoration at the Tuesday Club since the spring of 2019.

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The Caudron CA-50 has been through rough times and even malicious damage during its 93 years of storage. The fuselage of CA-50 when brought to the Finnish Aviation Museum is in a depressing state. All the metal parts are covered with thick rust. The plywood surfaces of the forward fuselage are soiled. In July 1928 the fuselage was totally rebuilt by the State Aircraft factory Santahamina branch. The paint surface has been badly damaged.  During the long storage it has badly cracked. There are also many holes and tears in the fabric. On the port side of the fuselage by the cockpit the fabric has been torn open and the paint has badly flaked.

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The landing gear which is covered in thick rust is without the suspension bungee cords. The starboard side wheel is French. The tyre bears the text NEUILLY-AVIATION-AERO  750-125. The wheel must therefore be an original Caudron wheel. Part of the rubber surface has been peeled off. On the port side of the landing gear is a British wheel PALMER CORD AERO TYPE 750x125. The fabric spoke covers of both wheels are on the brink on disintegration, because the rusty spokes have caused the fabric touching them to rot away. The tail wheel is structurally sound.  The metal parts are covered with rust, but the bungee cord still remains.

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The Caudron fuselage is without its Hispano-Suiza 8A engine. In the engine bay are the rows of bolts with their nuts for assembling the engine. The engine bay plywood surfaces are covered with thick dust and dirt. Outside, underneath the engine bay is the rusted assembly frame of the Lamblin radiator. The radiator is missing. On both sides of the nose there are several inspection hatches. They are functioning, but the hatches lack the Fokker pins to secure them.

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The steering wires from the cockpit to the tail are rusty and they have been tied to a bunch on the fuselage. There are no instruments in either of the cockpits. They have been probably dismantled when the aircraft was written off and stored. The pilots’ rattan seats remain. There’s no control column in the front cockpit. The rear cockpit has one.  Both cockpits have the rudder pedals in place. On the left wall of both cockpits the throttle and mixture levers and their connecting rods are all covered with thick rust. There’s plenty on muck and dirt on the rear cockpit floor.

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Our first task in the Tuesday Club is to clean the plywood surfaces and engine bay of the dust and dirt and clean up the cockpits. The fabric surfaces will not be touched for the time being because the badly cracked surface, when touched, will easily lose more bits of paint.
The landing gear will be dismantled and taken to parts to be cleaned. At the same time the fuselage can be lowered for easier handling.

Photos: Lassi Karivalo

Translation: Matti Liuskallio.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, Caudron C.59, CA-50

Fuselage of Caudron C.59 came to Finnish Aviation Museum from Vesivehmaa

Sunnuntai 31.10.2021 - Tuesday Club member

Suomeksi

On Tuesday, October 26th the fuselage of the Caudron C.59 (CA-50) arrived by the Defence Forces transportation at the Finnish Aviation Museum from the Päijänne-Tavastia Aviation Museum at Vesivehmaa.

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The Caudron’s fuselage is in poor condition, and it was brought to the Finnish Aviation Museum to be restored by the Tuesday Club. The Caudron’s lower wings and its tail parts have been under work at the Tuesday Club since the spring 2019. The Covid-19 pandemic interrupted the restoration work in March 2020, but from the beginning of September 2021 the work has been continued in the restoration space of the Finnish Aviation Museum.

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Now that the fuselage has arrived, the first task is to make an inventory of its present condition and to make a restoration plan for it. The principle in the restoration work is that as much as possible of the original fuselage will be preserved. The rusty parts and equipment will be restored, the broken items will be repaired and the parts which are beyond repair, will be rebuilt. One of the challenging items in the restoration of the Caudron’s fuselage will be the badly cracked painted fabric covering on the fuselage.

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The two-seater fighter trainer Caudron C.59 was in use in the Finnish Air Force in the 1920s. In late 1923 the Air Force purchased three Caudron C.59 aircraft to be used in the advanced training of fighter pilots. The CA-50 is the only one which has been preserved. It is most likely the only remaining Caudron C.59 aircraft in the world. The CA-50 flew its last flight in the Air Force on October 1st, 1929 – which was 90 years ago. Then the aircraft was written off and stored to be placed later in a museum. The aircraft was stored at Santahamina until the end of the 1940s, then it was moved – along with several other old aircraft waiting to go into a museum – into the WW2 aircraft hangar at Vesivehmaa airfield. Today the hangar is the home of the Päijänne-Tavastia Aviation Museum.

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In two years, it will be 100 years from the Caudron C.59 aircrafts’ arrival in Finland. We are wondering whether if it would be possible to complete the restoration of the Caudron CA-50 before that?

Photos: Lassi Karivalo

Translation: Erja Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, Caudron C.59, CA-50

Filler ring and supporting ring of Myrsky?s NACA-ring

Maanantai 25.10.2021 - Tuesday Club member

Suomeksi

The NACA-ring of the VL Myrsky II is complicated to build. Fortunately the most difficult phases of work have already been completed at the Tuesday Club when building the ring for the Myrsky MY-14 engine, which is under restoration. When the NACA-ring and its parts have been chromated and the fastener consoles, among others, have been fastened on the inner surface of the ring, the NACA-ring can be test assembled on the Pratt & Whitney R-1830 engine, which is available at the Finnish Aviation Museum.

It is rather fortunate that this engine is on display at the Aviation Museum and there is no need to travel for the test assembly all the way to Tikkakoski, where the Pratt & Whitney engine has already been assembled on the MY-14 fuselage, under restoration at the Finnish Air Force Museum. The engine, which is available at the Finnish Aviation Museum, has been on a DC-3 but it suits well for the test assembling of the Myrsky’s NACA-ring.

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The Tuesday Club team has been working lately on the filler batten ring (täyterengas), which will be fastened on the edge of the NACA-ring (NACA-rengas), as well as the supporting ring (moottorin suojuksen kannatinkehä) for the engine fairing. The supporting ring is fastened on the filler ring and its edge extends 30 mm outside the NACA-ring’s edge. The supporting ring forms a base outside the NACA-ring’s hem for the edge of the engine fairing. The supporting ring is covered with leather (nahkapehmuste) to absorb the resonance between two aluminium surfaces, which is caused by the engine.

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First the filler ring, a 40 mm wide ring cut from 2,5 mm thick aluminium sheet, was fastened on the edge of the NACA-ring. The filler ring was shaped to match the curvature of the NACA-ring’s edge and preliminarily fastened on it with clamps. Then the filler ring was fastened with small bolts. When the ring was firmly in place, the bolts were replaced with flathead machine screws so that the surface of the filler ring is smooth when the supporting ring is assembled on it. Eventually both the filler ring and the supporting ring will be riveted on the NACA-ring.

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85 mm wide strips were cut from 1,5 mm thick aluminium plate for constructing the supporting ring. One edge of each strip was bent to form a small gutter. Then the strips were shaped against the filler ring to match the curved shape of the NACA-ring. In the shaping process the supporting ring is also pressed tightly against the filler ring surface. When this had been achieved, holes were drilled through the supporting ring and the filler ring, and the supporting ring was fastened on the filler ring using small bolts.

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The filler ring and supporting ring had to be made also where the machine gun barrels penetrate the NACA-ring. This was not easy because the machine gun barrels form “bumps” on the edge of the NACA-ring. This means that the filler ring and the supporting ring had to be shaped to match the gun barrel “bumps”. Several rounds of modifications had to be made before the filler ring and the supporting ring fitted nicely into place at the barrel “bumps”. During the modification process it had to be checked that the edge of the supporting ring extended exactly 30 mm outside the hem of the NACA-ring.

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When the supporting ring had been preliminarily fastened, a line of holes was drilled through the ring and the filler ring under it for the future riveting work. Crosshead bolts were placed temporarily into the rivet holes. Now it could also be checked how the air intake duct of the air horn fits against the supporting ring between the machine gun barrels.

Photos: Lassi Karivalo

Translation: Erja Reinikainen

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, VL Myrsky, MY-14

Lower side of Mi-8?s port side tail boom stabilizer has been covered

Sunnuntai 17.10.2021 - Tuesday Club member

Suomeksi

The covering of the Mi-8P helicopter’s tail boom stabilizers is on the way at the Tuesday Club. The helicopter with the identification HS-6 was used by the Finnish Air Force and Army during 1978-2007. The HS-6 would have ended up being scrapped if a place hadn’t been found for it at the Tuulonen shopping centre.

The tail boom stabilizers were originally covered with aluminium sheet on the leading-edge side of the spar. On the trailing-edge side the stabilizers are fabric-covered. The HS-6 has been stored outdoors for almost fifteen years and the fabric covering on the tail boom stabilizers has decayed and needs to be replaced.

The rotten fabrics have been removed at the Tuesday Club and the work on the new covering has been started. The new covering will be made of aluminium sheet, not fabric, as the leading edge already has. The reason for this is that the HS-6 will be on display outdoors also in the future, so using a more weather-resistant material for covering the stabilizers is preferred. This is a good reason, especially as the aircraft is not a museum item. When repairing and restoring a museum item, the aim is to use original materials and work methods.

The covering material is 0.30 mm thick, used offset plates, made of aluminium. They are excellent for this purpose, with good workability. They are printing plates, so they already have an adhesive surface for the future painting work.

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The first surface to be covered with the sheet metal was the tail boom’s port side stabilizer’s lower surface. First the root end of the stabilizer was covered. Its fabric covering had been removed and a piece matching the shape of the fabric was cut from the aluminium sheet. The cutting was done so that the piece of aluminium was about 10 mm larger at its edges than the piece of fabric. This was necessary because the edges of the sheet will be bent over the butt rib’s lower and upper edges. Eventually the bent edges will be covered by the metal sheets, which cover the upper and lower surfaces of the stabilizer and are riveted on the butt rib.

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A mould was made from plywood for bending the root sheet edges. The mould is triangular and matches the size of the removed piece of fabric. After the edges of the sheet had been bent, the finalizing work was done with a file. When the root sheet was ready, it was riveted on the butt rib with a couple of flathead rivets.

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The next step was to make a cardboard model of the stabilizer’s surface which was to be covered. The Tuesday Club team realized that the aluminium offset plates were not large enough for cutting one single sheet which would cover the whole surface which needed to be covered. The upper and lower side of the stabilizer will both have to be covered with two aluminium sheets, which are joined together with a butt joint. The joint will be on top of the rib located in the middle of the stabilizer. An aluminium plate 5 cm wide was riveted on top of this rib to form a base for the butt joint.

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The cardboard model was used when the new covering sheet for the stabilizer’s root section was drawn on the aluminium sheet. The covering sheet for the stabilizer’s tip section was drawn on another aluminium sheet. Then the sheets were cut and fitted on the stabilizer. It was noticed that both covering sheets were slightly too wide and a strip a couple of millimetres wide had to be cut from their trailing edge. Now the sheet edges were exactly on the level of the trailing edge.

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The covering sheets were riveted on the stabilizer and this work was started on the root section. The covering sheet was placed on the stabilizer ribs and locating holes were drilled into its corners. Locating pins were placed in the holes to keep the sheet in place during the riveting work. The following phase of work was to mark the places for the rivets on each rib and on the trailing edge batten. For the marking a perforated galvanised steel fixing strap was used (i.e. a strap for supporting ventilation ducts). This is a good method for marking the rivet holes nicely at even distances. Then a metal point and a hammer were used for making a starting point for drilling at each rivet location. Then the rivet holes were drilled.

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Pop rivets were used when riveting the aluminium sheets into place. The pop rivet was pushed into the drilled hole and squeezed tight using a pop rivet hand tool. When the aluminium sheet on the tail boom port side stabilizer’s lower side root section had been riveted, the same procedure was used when riveting the sheet on the tip section. The lower side of the tail boom port stabilizer has now been covered and the next phase will be the covering of the stabilizer’s upper side.

Photos: Lassi Karivalo

Translation: Erja Reinikainen

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, Mil Mi-8P, HS-6

Other work than restoration

Keskiviikko 6.10.2021 - Tuesday Club member

Suomeksi

The Tuesday Club does not only do aircraft restoration projects - the team carries out also other assignments, which are connected to the activities of the Finnish Aviation Museum and the Aviation Museum Society.

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During the autumn the dust removing work has been started in the Finnish Aviation Museum’s Hall I and Hall II. A major dusting the museum aircraft surfaces was done about three years ago. Now mainly the surfaces of the aircraft on the museum floor are cleaned, because the dusting of the aircraft hanging from the ceiling requires a lifting platform, which isn’t available at the moment. The surfaces of the aircraft in Hall I are already bright and clean for the visitors to admire.

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There are some aircraft fuselage frames and rear fuselages stored on the yard of the Aviation Museum. These include the rear fuselages of Bristol Blenheim (BL-180) and Douglas DC-3 (OH-LCA). Of the Blenheims which were in use in Finland, the BL-180 belongs to the series V. The OH-LCA was destroyed in 1963 when it hit the trees when landing on the Maarianhamina airfield. During the years the tarpaulins which have covered the rear fuselages have ripped and decayed and they were renewed. The DC-3 tarpaulin was replaced already earlier this year. The Tuesday Club team helped the museum staff to remove the torn tarpaulin from the BL-180 fuselage and covered it with a new one.

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During the summer there is a fenced Children’s World outside the Finnish Aviation Museum. There young visitors can drive around on the pedal aircraft, made by the Tuesday Club, or “fly” in the real Cessna 172 Skyhawk (OH-COO), which was purchased for this purpose. In the autumn the Children’s World was closed and prepared for the winter. The Tuesday Club team helped the museum staff to take down the surrounding fence and to move the Cessna under the wing of the neighbouring DC-3 “Lokki” (OH-LCD) for the winter.

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The Tuesday Club team has made aircraft-shaped pot coasters which have been for sale in the Aviation Museum shop as well as in the webshop of the Aviation Museum Society. These popular pot coasters ran out, but more will be made during the autumn.

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Photo: Janne Salonen.

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Photo: Janne Salonen.

The Aviation Museum Society’s Caravelle-project has now taken a step forward as the airport company Finavia and the Aviation Museum Society have agreed that the Sud Aviation SE 210 Caravelle III, which has been standing in Arlanda in Sweden, will be placed on display at the Turku airport. A taste of Caravelle has already been sent to Turku: the main landing gear of a Super Caravelle. The landing gear is owned by the Aviation Museum Society, and it was cleaned at the Tuesday Club before it was delivered to the Turku airport terminal and placed on display there.

Photos: Lassi Karivalo except if separately otherwise mentioned.

Translation: Erja Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, Tuesday Club

Stieglitz SZ-18 at Tuulonen shopping centre was cleaned

Maanantai 4.10.2021 - Tuesday Club member

Suomeksi

Focke Wulff w 44 Stieglitz (SZ-18), which is owned by the Aviation Museum Society, has been on display for some years at the Tuulonen shopping centre in Hämeenlinna. Earlier the Stieglitz was on display at the Tuurin Kyläkauppa shopping centre. The SZ-18 has been restored by the Tuesday Club.

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The Stieglitz SZ-18 has already been at the shopping centre a number of years and dust had gathered on its surfaces. It was time to do some cleaning. It was agreed with the shopping centre that two members of the Tuesday Club will come and do the cleaning. The shopping centre will provide the equipment and a scissor lift. The aircraft is hanging from the ceiling of the shopping mall atrium and a scissor lift is needed when the aircraft’s surfaces are cleaned without lowering the aircraft to floor level.

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When the Tuesday Club members arrived at Tuulonen on September 15th, everything was ready for the cleaning work: an industrial vacuum cleaner, mops, cleaning cloths and buckets, filled with water. But first some coffee. Then the cleaning team climbed on the scissor lift and the work was started. The shopping centre staff moved the scissor lift under the aircraft during the cleaning.

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First the heavy layer of dust was vacuumed from the aircraft’s surfaces and then the surfaces were mopped with damp mops and cloths. The shopping centre staff rinsed the dirty mops and cloths in buckets and changed the water in the buckets when the scissor lift was moved. The co-operation worked well, and the cleaning progressed efficiently. The Tuesday Club team commented the good co-operation by saying that “the Tuulonen guys were really nice, and this task leaves a good memory”.

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Now the Aviation Museum Society’s Stieglitz is shining bright again and can be admired by the customers of the Tuulonen shopping centre. The customers can also see other aircraft on display at the Tuulonen shopping centre. There is a DC-2 (DO-1) “Hanssin Jukka” in a hangar, and Saab 35FS Draken (DK-247) and Mig 21 BIS (MG-124) fighters and Mil Mi-8P (HS-6) helicopter on the yard. The Tuulonen shopping centre is already a small aviation museum for the aviation history enthusiasts and other customers to enjoy.

Photos: Kimmo Salomaa

Translation: Erja Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, Focke-Wulf Fw 44 Steglitz, SZ-18

Super Caravelle's towbar is being repaired at Tuesday Club

Torstai 23.9.2021 - Tuesday Club member

Suomeksi

The Aviation Museum Society has an original towbar for Sud Aviation SE 210 Super Caravelle, which has been used by Finnair, but is now in poor condition. The towbar still has a Sud Aviation manufacturing plate on it. The towbar was donated by Swissport, where it has been stored outdoors since the Caravelles were removed from operation in the 1980s. The towbar will be restored into its original Finnair appearance as a part of the Caravelle-project, which aims to place the Caravelle SE-DAF (Caravelle III version) from Arlanda on display in Finland.

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The restoration of the towbar will involve a lot of work: the five-meter-long towbar is covered in a heavy layer of rust, due to the long storage outdoors. The original layers of paint have almost completely been destroyed by rust.

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The towbar has been painted light blue with bright yellow signal colour at both ends. Fortunately there is some original blue paint visible on the lower side of the towbar and under the brackets and some yellow at the ends. In the middle there is the text Super Caravelle, painted in white and barely visible.

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At the tow-vehicle end of the towbar there is a shaft with a spring, which is pushed into the towbar.  The spring of the shaft is located inside the towbar. There is a pull-eyelet at the end of the shaft to fasten the towbar on the hook of the pulling or pushing vehicle. The shaft has rusted and doesn’t move. The aim is to restore it into an operating condition.

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At the other end of the towbar there is a tow-fitting for fastening the landing gear heads, which are aircraft type specific. The Caravelle nose landing gear head is fork-shaped and has six metal pins to lock it on the tow-fitting. The pins are secured with fokker pins at their lower end. The towbar is fastened on adapter on the aircraft’s nose wheel with the landing gear head, which has a shear pin. The tow-fitting, the landing gear head, and the shear pin will be restored into operating condition.

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In the middle of the towbar there is a pair of wheels for moving the towbar. The wheels are located slightly off the towbar’s longitudinal centre of mass. Therefore the end with the pull-eyelet tilts towards the ground. Under the towbar there is a metal leg which balances the towbar and prevents the pull-eyelet from touching the ground. The shear pin of the towbar is kept on the wheel arm, which has brackets with holes for holding the shear pin.

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The wheel rims and the wheel arms have rusted, and they will be cleaned and painted. The outer tyre on the starboard side has broken and so has probably also the inner tyre. New outer and inner tyres will be installed. The outer tyre on the port side is still intact and in good condition. There is still air inside the tyre, it is probably “old air” from the 1980s.

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At both ends of the towbar there is a rectangular metal hoop. These hoops were used when the towbar was moved, or its end was lifted when it was fastened on the pushing/pulling vehicle or on the aircraft’s nose wheel. One of the hoops has disappeared but its holder holes can be seen on the towbar surface. A new lifting hoop will be made.

The restoration of the Caravelle towbar will begin by dismantling it into pieces as far as possible. That won’t be easy because the towbar and its parts with their fastening bolts and nuts have rusted badly. For disassembling the parts rust removing chemical has been applied. If necessary, the parts will be disassembled by heating.

The larger rusted parts of the towbar will be cleaned by sandblasting, this will be done by a contractor. The smaller parts, such as bolts, pins, locking pins and nuts can be sandblasted using the sandblaster at the Finnish Aviation Museum.

When all the parts of the towbar have been cleaned from rust, the parts will be painted with undercoat paint which will prevent rusting. On top of that a finishing layer of light blue and bright yellow paint will be applied. Before sandblasting the hue of the blue and the yellow will be defined from the original painted surfaces which are still visible.

The text Super Caravelle in the middle of the towbar has almost faded away, but it can still be copied on transparent paper or plastic. The text will be repainted on the restored towbar.

Photos: Lassi Karivalo

Translation: Erja Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, Caravelle

Tail boom stabilizers of Mil Mi-8P (HS-6) are being covered

Tiistai 14.9.2021 - Tuesday Club member

Suomeksi

The tail boom stabilizers of the Mil Mi-8P (HS-6) helicopter, which is on display on the yard of the Tuulonen shopping centre, have been brought to the Tuesday Club to be repaired. The HS-6 helicopter was on display outside the Finnish Aviation Museum for a long time then, some years ago, it was moved to Vesivehmaa, to stand in front of the Päijät-Häme aviation museum hall. The helicopter was approaching scrapping, but fortunately a place was found for it at the Tuulonen shopping centre. The shopping centre has quite a remarkable collection of different aircraft on display: Saab 35FS Draken (DK-247) and MiG 21 BIS (MG-124) fighter jets on the yard and Douglas DC-2 (DO-1) “Hanssin Jukka” and Focke Wulf Fw 44 Stieglitz (SZ-18) indoors. The shopping centre can already be called a small aviation museum.

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The tail boom stabilizers of HS-6 consist of an aluminium frame and are half covered with fabric. The fabric covers the area between the stabilizer’s trailing edge and the spar, about half of the stabilizer’s area. The fabric areas have been badly damaged because the HS-6 has been standing outside since the Defence Forces removed it from service in 2007.

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The task of the Tuesday Club team is to remove the decayed fabric covering and to replace it with a thin sheet of aluminium. The Mi-8 can’t be considered an actual museal artefact anymore and the fabric covering would rot again as the helicopter is permanently on display outside the Tuulonen shopping centre.

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The work was started by removing the rotten fabric from the stabilizer. The aluminium ribs and other surfaces, which had now been revealed, were cleaned. The stiffening steel batten, running parallel to the stabilizer’s spar, had rusted and it was cleaned. The paint on the stabilizer’s aluminium surface had partly flaked off. The flaked paint was removed, and the surface was cleaned to clear aluminium.

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A cardboard model was made of the stabilizer’s surface which will be covered with a sheet of aluminium. The covering sheets will be cut from aluminium plate according to the cardboard model and riveted on the upper and lower side of the stabilizer. The cardboard model was fitted on the upper and lower surfaces of both stabilizers. It turned out that the Russian helicopter engineers has designed the stabilizers to be symmetrical. This means that the cardboard model can be used for cutting adequately accurate aluminium sheets for the upper and lower surfaces of both stabilizers.

Photos: Lassi Karivalo

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, Mil Mi-8P, HS-6

Fabric covering of Caudron C.59 wings is being patched

Sunnuntai 12.9.2021 - Tuesday Club member

Suomeksi

When the Tuesday Club activities were interrupted because of the Covid-19 pandemic in March 2020, the holes and tears on the fabric covering of the lower wings of Caudron C.59 (CA-50) were being patched. The damages on the lower port wing had already been patched. The tears on the fabric covering of the starboard wing had already been sewn and the patches had been cut from linen fabric, they were waiting to be glued with shrinking varnish. There are plenty of holes to be patched on the covering of the lower wings, about 50 on both surfaces.

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Now the Tuesday Club can continue its activities again and the Caudron’s starboard wing is underway again. First the surfaces of the fabric-covered lower wing were vacuumed and the wiped with a damp cloth. Then the correct patch had to be found for each hole on the lower wing. Fortunately the holes and the patches had been numbered, so the pairing was easy. During the 18-month break the patches had been carefully stored and none were missing.

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Each patch was placed on its matching hole. Then a protecting circle was taped around each patch so that the gluing varnish will not spread outside the patched area.

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When all the patch areas had been surrounded with tape, nitrocellulose varnish (shrinking dope) was spread on the area inside the tape circle. The edges of each patch had been unravelled and the patches were pressed on the wet varnish. More varnish was applied on each patch so that the fabric and the unravelled edges became thoroughly wet. The unravelled edge will make the edges of the patch fasten better on the original fabric covering. This was the work method when the fabric covering was patched in the 1920s and 1930s.

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The protecting tape was removed soon after the varnishing so that the glue of the tape won’t harden on the fabric surface. If the tape is left on the painted surface of the fabric covering for a long time, it is possible that the tape will leave a mark on the painted surface when it is removed.

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When the varnish had dried, the patches had shrunk nicely on the holes and damaged areas. The surfaces of the fabric patches and their unravelled edges were ground smooth using a fine grinding pad. The patches will be varnished and ground at least a second time so that the surface becomes very smooth before it is painted. The patched areas will be painted greyish green to match the hue of the Caudron’s wing surfaces, which have been painted in the 1920s and gained patina during the decades.

Photos: Lassi Karivalo

Translation: Erja Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, Caudron C.59, CA-50

Tuesday Club activities are continued

Tiistai 7.9.2021 - Tuesday Club member

Suomeksi

During the Covid-19 pandemic a small Tuesday Club team has been working on the VL Myrsky restoration project. Tuesday August 31st was a day of joy: finally, after a break of about 18 months, the other Tuesday Club activities could be continued. The main work item is the restoration of the Caudron C.59 trainer fighter, which is now in the restoration space of the Finnish Aviation Museum.

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Photo: The photo archive of the Finnish Aviation Museum.

However, there are still some restrictions and Covid-19 instructions from the Finnish Aviation Museum and the Tuesday Club is not able to start with full capacity. The number of workers in the restoration space is still limited and everybody working there is still wearing a mask.

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In order to involve as many Tuesday Club members as possible in the Caudron restoration work, the team has been divided into two groups and works in the restoration space on Tuesdays and Wednesdays. This allows about twenty club members to work on the Caudron and on other projects, too. The Myrsky team continues to work on three days a week.

The Caudron C.59 restoration is continued, now the holes on the lower wings are being repaired. About 18 months ago the lower port wing was patched and the patches were made for the starboard wing – then the Covid-19 pandemic interrupted the Tuesday Club activities. Now the patching of the starboard wing is in progress again.

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The tail boom stabilizers of the Mil Mi-8P (HS-6) helicopter, which is on display on the yard of the Tuulonen shopping centre, have been brought to the Tuesday Club to be repaired. The stabilizers are partly covered with fabric and the fabric has decayed, because the helicopter has been on display outdoors since it was removed from service in 2007. The fabric covering will be renewed by the Tuesday Club team.

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One of the most unique projects the Tuesday Club has come across is the preparation of a DC-3 instrument panel for a movie. A proper DC-3 instrument panel will not be made, but a reasonably plausible version anyway.

Photos: Lassi Karivalo except if separately otherwise mentioned.

Translation: Erja Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, Caudron C.59, CA-50, Mil Mi-8P, HS-6, DC-3

Work on Myrsky's landing gear wheel hub cover is continued

Torstai 26.8.2021 - Tuesday Club member

Suomeksi

The Tuesday club team has continued preparing the cover which is fastened on the wheel hub of the starboard wing landing gear on the VL Myrsky II (MY-14). At the moment the metal support is being made for the inner edge of the cover. The support circles the edge of the cover, and it is made of 15 mm thick square steel tube. It is fastened at a 10 mm distance from the edge of the cover.

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The square tube is a supporting frame for the cover, cut from aluminium plate, and it also forms a fastening surface for the stiffeners which are fastened on the inner side of the cover. The stiffener plates, cut from aluminium plate, are riveted on the cover so that the square tube is between the cover and the stiffener plate. The stiffener plates are waiting to be assembled. The stiffeners on the test wing’s wheel hub have already been riveted. The wheel hub cover of the test wing has been used as a model when the actual covers for the landing gear are made.

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The upper edge of the wheel hub cover is curved, and the square tube had to be modified in a mangling machine to make it match the cover shape. The shape was modified step by step. When the square tube began to curve, its shape was compared to the curved edge of the cover and mangled again. When the desired curved shape had been reached, the square tube was cut into pieces which will be fastened on the cover’s upper edge.

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The lower edge of the wheel hub cover is not curved but angular. A piece of the square tube was cut for the cover’s lower edge. To modify the square tube into an angular piece, a cleft was sawed at the point where the cover edge has its steepest angle. Several clefts were made where the slighter angle is. The tube was bent, using the clefts, to meet the shape of the cover’s lower edge.

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The following phase was to mark with tape the line of the corner joint, where the curved square tube on the upper edge of the cover meets the angular square tube of the lower edge. The tube ends were cut slanted according to the marked line. The slanted tube ends were placed against each other and fastened on the cover plate with clamps. At first the tube ends will be lightly welded together so that the whole tube frame can be moved from the aluminium cover plate for the actual welding work. When this has been done, the square tube forms a complete supporting frame along the edge of the wheel hub cover.

Photos: Lassi Karivalo

Translation: Erja Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, VL Myrsky, MY-14

Stiffeners were riveted on cover of landing gear oleo strut on Myrsky's starboard wing

Maanantai 23.8.2021 - Tuesday Club member

Suomeksi

The Tuesday Club team has continued its work on the covers for the Myrsky fighter’s landing gear on the starboard wing. U-profile stiffening battens were riveted on the cover of the oleo strut, which was otherwise ready. The stiffeners were cut from aluminium plate and pressed into shape. They are riveted on the inside edge of the cover. The cover and stiffeners have already been chromated.

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The riveting was started by fastening the first of the four stiffening battens on the edge of the cover with cleco fasteners. Clecos, which are fastened in the rivet holes with nose pliers, are used for the temporary fastening of work pieces which will be riveted or welded together. In spite of the cleco-fastening, the rivet holes had to be slightly shaped with a round file to make the rivets slide nicely into their holes.

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The rivets used were 3x6 mm flathead rivets. The stiffeners were riveted on the cover plate rivet by rivet. A compressed air riveting gun was used. All four stiffeners have now been riveted. The cover plate has been preliminarily assembled on the oleo strut of the starboard wing. It fits nicely into its place.

Photos: Lassi Karivalo

Translation: Erja Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, VL Myrsky, MY-14

Works on Myrsky carburettor air intake and NACA-ring

Tiistai 22.6.2021 - Tuesday Club member

Suomeksi

The half-finished air horn and air intake ducts have been preliminarily assembled on the VL Myrsky II which is under restoration. The Myrsky had a Pratt &Whitney R-1830 radial engine and a similar engine is available at the Finnish Aviation Museum. Fortunately it has been possible to test the assembly at the museum and there is no need to travel to the Air Force Museum at Tikkakoski, where a similar engine has already been installed on the Myrsky’s (MY-14) fuselage.

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Holes for the fastening bolts were drilled on the cast aluminium air horn and the air horn was fastened with a couple of bolts onto the carburettor of the engine, located in the museum hall. It fitted nicely into its place. Then the two air duct sections could be assembled into place between the air horn and the NACA-ring.

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The Tuesday Club team noticed that the section of the air duct, made of steel plate because of its location above the hot engine, did not fit properly. The reducers made on its lower part were too shallow and the air intake duct couldn’t be pressed sufficiently deep between the cylinder head covers. The air intake duct was heated using a welding flame and shaped to fit better. Then the two air intake duct sections were assembled above the engine and fastened on the air horn. Even when half-finished it is a great sight!

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The consoles of the NACA-ring, which are needed to fasten the ring on the brackets on the cylinder heads, had to be modified before riveting on the edge of the NACA-ring. Especially the console hems have needed shaping. The console is riveted on the NACA-ring by its hem. The hem has to meet the curved shape of the NACA-ring and to take into account the filler batten, which is a 2,5 mm aluminium batten riveted on the edge of the NACA-ring, and the 1,0 mm aluminium supporting frame of the engine fairings. The supporting frame is 75 mm wide, and it is riveted on top of the filler batten so that it extends 32 mm outside the edge of the NACA-ring. It forms a shoulder on which the edge of the detachable engine fairing rests and meets the edge of the NACA-ring in a butt joint. There is a very general overview picture of this structure attached.

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Translation: NACA-renkaan reuna = Edge of NACA-ring, 3,5 mm porrastus = 3.5 mm offset, Kiinnityskonsoli = Console, Moottorin vaippalevyjen tukikehä = Supporting frame of detachable engine fairing rests, Täytelista = Filler batten, Moottorin vaippalevy = Detachable engine fairing rests.

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The hems of the NACA-ring consoles were shaped using pliers and a plastic-headed hammer and a piece of wood. A 3,5 mm offset was made on the upper end of the console for the filler batten and the supporting frame. All console hems have now been shaped and are ready to be riveted into place. Before that can be done, the filler batten and the supporting frame on top of it will have to be riveted onto the edge of the NACA-ring. The supporting frame is made of four sections and the sections are ready to be installed.

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Up to now the filler batten has been fastened on the upper edge of the NACA-ring with clamps. Now it is debated how the riveting of the filler batten and the supporting frame on the NACA-ring edge will be done so that the filler batten settles exactly to the same level as the NACA-ring’s edge.

Photos: Lassi Karivalo.

Translation: Erja Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, VL Myrsky II, MY-14

Myrsky's starboard wing half was turned for installing landing gear

Sunnuntai 13.6.2021 - Tuesday Club member

Suomeksi

The assembly of the landing gear has been started on the wing halves of the VL Myrsky II (MY-14), which is under restoration at the Tuesday Club. Thorough test assembly has already been done on the test wing which was prepared in the Myrsky-project. The test wing is a 2,5 metres long root piece of the wing, meant mainly for testing the landing gear installation. The landing gear will first be assembled on the starboard wing half.

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The wing halves were painted with undercoat paint and after this work they remained on the worktable the upper side up. First the starboard wing had to be turned so that the landing gear well is facing upward, and the landing gear can be installed. The wing halves have already been turned around several times during the different work phases. For this purpose steel supports have been made for the wing tip and the wing root and they are used to support the wing when it is lifted and turned.

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Two lower photos: move the cursor over photo and you will see more photos!

The turning supports were fastened on the wing tip and the wing root. Then a lifting device was moved to both ends of the wing and the lifting devices were connected to the steel supports with cargo straps. Then the lifting devices were pumped, and the wing was lifted in the air, supporting it manually all the time. When the wing had been lifted high enough, the wing was tilted in order to turn it around. The wing was carefully manoeuvred onto one side by supporting it from the other side. When the wing had been turned, it was lowered back on the worktable and it was placed horizontally by supporting it at the ribs.

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Photos: Jorma Laakkonen.

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Photo: Jorma Laakkonen.

Now the landing gear well was facing upwards, and the landing gear assembly could be started, following the procedure developed when testing the gear on the test wing. The first preliminary test was to place the landing gear oleo strut in the well with its wheel hub and axle. At the same tame the wheel well doors were fitted into place. These include the diagonal support door, the oleo strut door, the wheel hub door and the opening door, which is fastened on the fuselage side edge of the wheel well. All parts seemed to settle nicely into their places.

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Photo: Jorma Laakkonen.

Now there is ahead the demanding work of fitting all the hinges and fastenings of the starboard landing gear into place so that the landing gear extends and retracts smoothly. The aluminium covers will also have to be assembled into place on the diagonal support, on the oleo strut and on the wheel hub. Another challenge is to fit into place the aluminium cover on the fuselage side of the wheel well and to make its opening and closing mechanism work as planned. This door is opened automatically by a spring lever when the landing gear is taken out. When the landing gear is retracted the wheel presses against a pin in the mechanism and closes the door.

Photos: Lassi Karivalo except if otherwise mentioned.

Translation: Erja Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, VL Myrsky II, MY-14

MY-14's vertical stabilizer gets its fabric covering webbing ribbons

Sunnuntai 6.6.2021 - Tuesday Club member

Suomeksi

When the webbing ribbons for the fabric covering had been sewn on the horizontal stabilizer ribs of the VL Myrsky II (MY-14), the sewing work continued on the vertical stabilizer. The vertical stabilizer has a wooden structure, according to the original drawings.

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Photo: Heikki Kaakinen.

The Tuesday Club team used the original drawing of the vertical stabilizer, prepared by the State Aircraft Factory and dated 30.9.1942, as instructions for the work. The drawing shows very well how the ribbons must be sewn. The bill of materials on the drawing shows a detailed list of the accessories needed in the work. The list includes the covering fabric, the webbing ribbons, cover ribbons and sewing threads. A 20 mm wide diagonally woven linen ribbon was used as the webbing ribbon.

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Photo: Heikki Kaakinen.

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Photo: Heikki Kaakinen.

In order to keep the webbing ribbons in place on the rib of the vertical stabilizer when doing the sewing, the ribbon was stretched on the rib and its one end was glued on the plywood of the leading edge and the other end on the plywood of the trailing edge. Contact glue was used in this work.

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Left photo: Heikki Kaakinen.

One more work phase had to be completed before the actual sewing could be started. The edges of the plywood sheet covering the leading edge had to be bent inwards so that the edges won’t chafe the fabric covering and gradually damage it.

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Photo: Heikki Kaakinen.

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Photo: Heikki Kaakinen.

To bend the plywood edges, 3 mm holes were drilled where the drawing indicated. Then the edges were bent against each other and tied temporarily into this position using painter’s tape. Linen thread was pulled through the drilled holes and then the threads were tied together into a tightening loop, connecting the edges of the plywood. Then the supporting painter’s tapes could be removed, and the sewing of the webbing ribbons could be started.

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Photo: Heikki Kaakinen.

The webbing ribbons for the fabric covering of the vertical stabilizer were sewn in a similar manner as on the horizontal stabilizers. At the tapered part of the rib the edges of the ribbon were stitched together. At the broader part of the rib, where the round lightening holes are, the thread was slipped through the lightening hole and fastened on the ribbon’s edge on the other side and repeating back again. A radial pattern of the threads was formed in the lightening hole. Now the vertical stabilizer had its webbing ribbons in place.

Photos: Lassi Karivalo except if otherwise mentioned.

Translation: Erja Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, VL Myrsky II, MY-14

Webbing ribbons for fastening fabric covering of Myrsky's horizontal stabilizer are sewn

Tiistai 1.6.2021 - Tuesday Club member

Suomeksi

The VL Myrsky II fighters had originally wooden horizontal stabilizers. The aeroelastic flutter caused the damaging and even breaking of the stabilizers. Therefore the Myrsky’s horizontal stabilizers were replaced with metal stabilizers, which endured the flutter.

The documents concerning the MY-14 which is under restoration don’t mention whether the aircraft got metal horizontal stabilizers before it was written off. However, the board of the Myrsky restoration project decided that the restored MY-14 would have metal horizontal stabilizers. One of the reasons for this was that there were original metal stabilizers available, but somewhat damaged and without covering.

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Photo: Heikki Kaakinen.

The original horizontal stabilizers with aluminium structure have already been repaired and painted by the Tuesday Club and they have been waiting for the fabric covering for a while. The metal stabilizers are covered with fabric in the same way as the corresponding wooden stabilizers. First fabric webbing ribbons are sewn on the ribs of the stabilizer. The fabric covering is fastened on these ribbons by sewing. The fabric is tightened using several layers of nitrocellulose varnish and finally painted according to the aircraft’s paint scheme.

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Photos: Heikki Kaakinen.

The Tuesday Club team has now started the sewing of the webbing ribbons on the MY-14’s horizontal stabilizers. To make the work easier, one of the stabilizers was fastened into an upright position against two trestles. The first step was to stretch a 20 mm wide linen upholstery webbing ribbon on the stabilizer’s ribs. This was done by gluing the ends of the ribbon on the rib at the leading edge. This way the ribbon will stay in place when sewing it onto the ribs.

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After the gluing the sewing could be started. The instruction drawing for sewing the ribbons on the wooden horizontal stabilizers was applied, because the instructions for the metal stabilizer have not been preserved. According to the instructions multithreaded 0,5 mm linen thread was used in the sewing work.

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The sewing work was started at the trailing edge end of the rib. The edges of the ribbon stretched on the upper and lower edge of the rib were stitched together. This was the method used at the tapered end of the rib where there are no lightening holes.

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When the work reached the broader part of the rib where the round lightening holes are, the sewing method was changed. Now the thread fastened to the edge of the ribbon was slipped through the lightening hole and to the other side to the ribbon’s edge, and back again. The webbing ribbon was sewn onto the rib following the original instructions, weaving the thread through the lightening hole.

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Photo: Heikki Kaakinen.

When the ribbons had been sewn on all the ribs of one stabilizer, the procedure was repeated on the other stabilizer. Now the horizontal stabilizers are ready for fastening the fabric covering. In the original drawing’s instructions the fabric quality has been defined as linen fabric 5.F.I.

Photos: Lassi Karivalo except if otherwise mentioned.

Tranlation: Erja Reinikainen

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, VL Myrsky II, MY-14

Myrsky engine's air horn and air intake are made

Perjantai 28.5.2021 - Tuesday Club member

Suomeksi

The air flow entering an aircraft’s carburettor is controlled in the air horn, which is attached to the carburettor. When necessary, there is an air intake duct connected to the air horn. This is the case in the VL Myrsky II fighter, among others. In the Myrsky the two-sectioned air intake duct is connected to the air intake, located at the top of the NACA-ring, and is led between the upper cylinders to the air horn of the two-throat carburettor behind the radial engine. The suction air flow is controlled with the damper located in the air horn as well as the warm air flow, which comes through the engine space and protects the carburettor from freezing.

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The Myrsky’s air horn is made of cast aluminium. The front piece of the two-section air intake duct, which is fastened on the NACA-ring, is made of aluminium plate. The tail section of the air intake duct is made of steel plate because it is located at a hot place between the cylinders. The tail section of the duct also connects the front section of the air intake duct to the air horn and is fastened to them with fastening clamps.

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No original Myrsky engine’s air horn or parts of the air intake duct have been preserved and they had to be made in the restoration project of the MY-14. The sections of the air intake duct have already been made. The front section of the duct was made according to the drawing from 1,0 mm thick aluminium plate, using a mould. The tail section was made from 1,0 mm thick steel plate. The sections of the air intake duct have been fitted into place and the front section of the duct is being fastened to the opening in the NACA-ring.

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The SASKY Municipal Education and Training Consortium at Sastamala helped to manufacture the air horn from cast aluminium. They were interested in the ongoing Myrsky restoration project and asked if there was some restoration work which could be made as 3d-printing by the SASKY students. The Tuesday Club team suggested that they could make the rather difficult air horn - and they accepted the challenge.

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Photo: SASKY

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The project was started at SASKY by 3d-printing a plastic 1:1 scale model of the Myrsky’s air horn according to the drawings. Then the actual cast mould for the aluminium cast was made based on the 3d-print. The 3d-printed model was dipped several times in a ceramic solution and a ceramic layer was formed, layer by layer, on the plastic model. Flow channels and air extract were also made on the cast mould. Then the plastic 3d-model was melted from inside the ceramic shell, and the cast mould for the air horn was ready. The liquid AlSi 12 aluminium was poured into the mould. When the aluminium had cooled the mould was broken and the flow channels were removed, and the surface was ground smooth.

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The cast aluminium air horn is now at the Tuesday Club and is ready for further work. Some extra material has been ground off. Holes for fastening bolts will be drilled. The Tuesday Club wishes to thank the SASKY Municipal Education and Training Consortium for preparing the aluminium cast of the air for the restoration the restoration project of the VL Myrsky II (MY-14).

Photos: Lassi Karivalo except if otherwise mentioned.

Translation: Erja Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, VL Myrsky II, MY-14

Wing root fairing of Myrsky?s port wing at Tuesday Club

Sunnuntai 11.4.2021 - Tuesday Club member

Suomeksi

The joint of Myrsky-fighter’s (VL Myrsky II) fuselage and wing is covered with a wing root fairing, made of 1 mm thick aluminium sheet. The wing root fairing consists of a short front section, which covers the leading edge of the wing and reaches under the fuselage. The longer rear section of the wing root fairing covers the seam of the fuselage and the wing, all the way to the trailing edge and around it.

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The rear section of the port wing root fairing was sent to the Tuesday Club for further modifications. It came from Flanco Oy where Antero Flander had forced it into shape against a mould. The Finnish Air Force Museum, working on Myrsky’s restoration at Tikkakoski, had made the sturdy plywood mould. The wing root fairing was made from three aluminium sheets, forced into shape against the mould and then welded together.

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The parts of the port and starboard wing root fairings, which cover the front section of the fuselage and wing joint, had already been sent from Flanco Oy to the Tuesday Club in Vantaa where the parts were welded together. The moulds for the front sections had been made by the Tuesday Club. Flanco Oy has helped in making several other metal parts that are needed in the restoration of the Myrsky MY-14.

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The Tuesday Club team had now both sections of the port wing root fairing and they could be preliminarily fitted into place at the root of the port wing.

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The front and rear sections of the wing root fairings will be finalized at the Tuesday Club, joined together and test assembled. The front and rear sections will be joined together with a joint where the aluminium plate riveted on the lower side of the rear section’s front edge is pushed under the front section’s edge. The holes have not yet been made for the flange nuts, which are used for fastening the wing root fairing sections to the side of the fuselage and to the wing surface.

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The wing root fairings will be test assembled when the wing halves, made and undercoat painted at the Tuesday Club, will be assembled on the fuselage frame of VL Myrsky MY-5 at the Finnish Aviation Museum. However, it will take some time before the wing root fairings are ready for the test assembly.

Photos: Lassi Karivalo

Translation: Erjan Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, VL Myrsky, MY-14

Wheel well and aileron inspection hatches on Myrsky?s test wing

Sunnuntai 21.3.2021 - Tuesday Club member

Suomeksi

When the undercoat painting of VL Myrsky II’s (MY-14) wings and tail part surfaces had been completed, the activity of the six Tuesday Club members working on the Myrsky project could be targeted to other things. The new work item is the test wing and the construction of its wheel well and the installation of the ailerons’ inspection hatch covers.

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The wheel well of the test wing is in the square space bordered by the front and rear spars and the wing ribs. The wall of the wheel well is made of 2 mm thick plywood. The wall billet had been cut earlier, now it was fitted into place by bending the plywood into a circle, in the space bordered by the spars and ribs. At the fitting stage the plywood wall was too tall for its space. When the wall had settled into place as desired, the excessive height was cut away and the plywood wall was fastened. The next phase was to make from plywood the corner pieces to cover the empty spaces in the corners of the wheel well.

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A supporting curb will be built on the upper edge of the plywood wall of the wheel well. The pressure lathed aluminium cover will be fastened on the curb to shield the wheel well. The covers have already been lathed for both wheel wells of the test wing. The supporting curb and the cover on the starboard wing half are already in place. The wheel wells and their covers will be hidden under the aluminium wing root fairings, which cover the seam of the Myrsky’s fuselage and wing.

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The supporting curb for the wheel well’s upper edge on the port side wing half was made from plywood strips which were glued together and forced into a mould. When the glue had dried, the supporting curb was unfastened from the mould and modified into measure and is now waiting to be installed.

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Simultaneously with the building of the wheel well, the fitting of the half-finished aileron inspection hatch covers was started. This task has been waiting while the ailerons were being painted with undercoat paint.

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The aileron is fastened on the wing with three hinges. The hinge knuckles inside the aileron’s leading edge are fastened on the journaled hinge arms on the wing with bolts. On the lower side of the aileron’s leading edge there is an inspection hatch for each hinge.

The opening of the inspection hatch has a cover made of 1 mm thick aluminium plate. The Tuesday Club team has one original hinge hatch cover as a model. The cover is for the hinge hatch in the middle of the aileron. However, the team made new covers for all aileron inspection hatches. On the front side of each inspection hatch opening there is a slot on the aileron’s surface for fastening the cover.

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These slots for fastening the inspection hatch covers had been covered during the undercoat painting of the aileron, when a strip of linen fabric was fastened to reinforce the leading edge. The covered slots were cut open with a sharp knife, then the inspection hatch covers were fitted into place, one by one. When the hatch is closed, the front edge of the cover is slipped into the slot in the aileron, then the cover is pressed against the aileron surface to cover the opening. The cover is locked into place with one or two screws, located on the rear edge of the cover. The screws are pressed and locked into the locking holes with springs. The new aluminium hatches don’t have the locking screws yet.

Photos: Lassi Karivalo

Translation: Erja Reinikainen

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, VL Myrsky, MY-14

Valmet Tuuli III (TL-1) returned to Finnish Aviation Museum

Lauantai 13.3.2021 - Tuesday Club member

Suomeksi

The restoration of Valmet Tuuli III (TL-1), which remained a prototype, is a joint venture of the Wednesday Club of the Finnish Aviation Museum and the Tuesday Club of the Aviation Museum Society. The restoration project started in 2016. When Tuuli III had been dismantled in the restoration space of the Finnish Aviation Museum, the fuselage, wings and parts of the tail were taken to the Tavastia Vocational College in Hämeenlinna.

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Photo: The photo archive of the Finnish Aviation Museum / Kauko Tuomikoski's collection.

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The aim was that the aircraft’s surface treatment is done by the students of the Tavastia Vocational College. This included the cleaning and painting of the surfaces. The work was started by degreasing the tail parts and wing surfaces. After that the silver paint surface was removed with Nitromors paint stripper, dry ice blowing and grinding.

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Photo: Antti Laukkanen.

The wings and tail parts had already been painted with yellow adhesion primer (acid primer), when it was discovered that the surfaces of Tuuli III had originally been clean aluminium surfaces. Only the belly, the leading edges and some decorative elements had been painted. The aim was to restore Tuuli III into its appearance during the test flight time. This meant that the adhesion primer, which had been sprayed on the wings, had to be removed. The fuselage surfaces had not yet been painted with undercoat paint at the vocational college.

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In February 2020 the students of the Tavastia Vocational College attended a surface treatment course at the aviation museum. They learned how to polish aluminium surfaces, using the Tuuli III fuselage as the target. After this the aim was that the Tavastia students continue with the polishing work.

However, Tuuli III work was interrupted in Hämeenlinna, because the Vocational College has been mainly remote in education due to the Covid-19 pandemic. Additionally, the space where the Tuuli III has been stored at the vocational college was needed for other purposes. Therefore, it was decided that the Tuuli III is returned to the Finnish Aviation Museum.

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When the Covid-19 pandemic situation allows, the volunteer activities at the museum will be started again and the restoration of Tuuli III can be continued. Surface treatment of the fuselage and wings will be the following phase and after that the aircraft will be assembled and the engine restoration continued.

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At the moment there is no vacant indoor space in the museum for continuing the restoration of Tuuli III. Due to the Covid-19 pandemic, the restoration work of VL Myrsky II (MY-14) and Caudron C.50 (CA-50) is still unfinished. For now, Valmet Tuuli III is stored at the museum premises in the new storage tent. The restoration work of Tuuli III can be continued in the tent, at least to some extent, during the summer period.

Photos: Lassi Karivalo except if separately otherwise mentioned.

Translation: Erja Reinikainen.

Kommentoi kirjoitusta. Avainsanat: aviation history, restoration, Valmet Tuuli III, OH-XTL, TL-1

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