Caravelle's Turku team and a nice Christmas lunch

Lauantai 23.12.2023 - Ismo Matinlauri

Suomeksi

On Tuesday, December 19th, the Caravelle Turku restoration group gathered for a Christmas lunch. The place was Krookila Wanha Tupa (Old Farmhouse). The history of the place goes as far back as 1490, and in the summer the farm is open to the public as a museum. We enjoyed a nice and traditional Christmas lunch in this historic and beautiful surrounding.

The group picture shows 13 members of the Turku team with Aviation Museum Society Finland chairman Janne Salonen and his mother Liisa Salonen. Liisa has participated in the Caravelle restoration project and has encouraged and cheered up the Turku team on several occasions. Our chief photographer Jouko Tarponen is missing from the picture – he was naturally behind the camera.

This team will continue its work with the Caravelle after a hopefully short winter break. If we are able to find a suitable warm workshop we will start restoring the passenger seat frames and cabin partition walls while waiting for the weather to get warmer.

Photos by Jouko Tarponen

Translation by Erja Reinikainen

MY-14 lateral machine gun caissons

Torstai 14.12.2023 - Reino Myllymäki

Suomeksi

The armament of VL Myrsky II consists of four synchronized heavy 12,7mm VKT machine guns, located in the front fuselage. Each machine gun has its own caisson. The machine gun caissons in the middle hold 220 and the lateral gun caissons 260 rounds.  

The VL Myrsky II restoration project has available three Myrsky fuselages (MY-5, MY-9 and MY-14). In all of them the original rails for the caissons were in place. In all these the rails were intact, but the steel parts were badly rusted. The original caissons couldn’t be found anywhere.

The MY-14 rails were picked out to be restored, dismantled from the fuselage and all the screws and rivets were taken apart. The rust from the steel parts was blown away with glass ball blasting, the surfaces were treated with Isotol-klarlack and painted grey. The aluminium parts were cleaned with glass ball blasting. The parts were riveted together again with aluminium rivets according to the blueprint, and the entity was painted grey all round. The refurbished rails were installed back to their original place.

The entirely new caissons were made according to the blueprints. The blueprints lacked the detail picture of the rear handle, the necessary measurements were obtained from the assembly blueprint. The finished caissons turned out to be slightly too big and they didn’t fit properly into place. The matter could be corrected by adjusting the rails and hammering the caissons. The left-hand caisson remained a bit ill fitting. This was mostly because the left-hand adjustment screws of the rails couldn’t be properly reached. The locking of the caissons was observed to be working.

How the caisson is fitted into place and locked: The caisson slides to place on a roller rail. The locking lever in the lower rail is turned up, and with a screw in the lever the caisson is tightened into place. The handle of the caisson is turned down and a locking peg inside the handle locks the handle in the down-position. The square-shaped tip of the locking screw leans now against the handle of the caisson and prevents the locking screw from turning on its own account. The steel front plate of the caisson is meant to guide the spent cartridges, coming from the gun above, into the collection box.

The caissons will be painted grey all over later, at the same time as other larger parts are taken to be spray painted.

Santa Claus visited Caravelle

Tiistai 12.12.2023 - Ismo Matinlauri

Suomeksi

On Saturday, December 9th, we had the pleasure to welcome Santa Claus on board our Caravelle. Santa turned out to be a competent pilot and well familiar with the Caravelle’s flight deck equipment. This is understandable – after all, he has hundreds of years’ experience of flying with reindeer.

The aircraft was open to the public, too. The weather was slightly colder than during the assembly phase in the beginning of June, now it was -5 degrees Centigrade. The rear pantry was in use for the first time, serving visitors glögg and gingerbread and juice boxes to the younger ones.

During the day we had 63 visitors, including about 15 children. The visitor from farthest away came from Portugal. The visitors were genuinely excited and interested about the airliner and stayed a long time despite the cold weather.

The hydraulic system of the rear stairway had been repaired a couple of days earlier so we could have the stair open during Santa’s visit. This way the visitors could move flexibly to the aircraft’s tail and behind it, where the Rantala crane truck was parked. The truck interested especially the youngest visitors.

After the last visitors, we topped up the bags of de-icing salt to make sure the de-humidifying continues inside the aircraft. Santa’s visit was a suitable closing for this eventful year in our Caravelle.

The Caravelle team wishes our readers Merry Christmas and a Happy New Year!

Photos by Ismo Matinlauri

Translation by Erja Reinikainen

The wings of a Link Trainer to the Tuesday Club to be covered

Sunnuntai 3.12.2023 - Tuesday Club member

Suomeksi

The collection of the Karelian Aviation Museum includes a Link Trainer (LT-1). This Link Trainer has last been in use at Immola. The retired link Trainer was collected in a trailer to the Karelian Aviation Museum to Lappeenranta on June 6th, 2004.

Photos by Kimmo Marttinen.

This Link Trainer has wooden wings with ailerons. The fabric covering of the wings is badly torn. On top of that the left aileron is missing. The wings are structurally more or less intact, so for that part there isn’t much to repair.

Photos by Ari Aho.

The chairman of the Karelian Aviation Museum, Mr Kimmo Marttinen, turned to the Tuesday Club, whether the Tuesday Club could cover anew the LT-1 wings. The Club has several restoration projects active, but we answered in the affirmative because the wings are tiny, and their covering anew won’t take much room. The LT-1 wings were brought from Lappeenranta to the Finnish Aviation Museum at the beginning of November.

Photo by Ari Aho.

Photo by Kimmo Marttinen.

At the Aviation Museum we examined more closely the Link Trainer’s fabric covered wings. There were damages on the covering of the upper surface of both the wings, but they could be patched. The covering of the underside of both the wings, instead, was badly damaged. However, we decided to cover both wings anew, because the end result wouldn’t be tidy, if it consisted of both old patched and new fabric covered surfaces.

Before we started to dismantle the covering, the right-hand wing’s aileron was taken off. Even though the covering was intact, it was dismantled. The reason for this being that we’ll have to build the lacking aileron for the left-hand wing, and for that we needed the structure of the right-hand aileron as a model. The structure of the aileron for building the lacking one can’t be seen without taking off the covering from the aileron.

When dismantling the covering fabric from Link Trainer’s wings, our attention was drawn to the thickness of the covering fabric.  At the same time it was noticed that where there was damage in the fabric, silver and dark blue paint appeared from under the beige paint. The Link Trainer’s wings have originally, or before the last coat of paint, been blue on the upper surfaces and silver on the undersurfaces.

The covering fabric also told us that the wing had been covered with fabric consisting of several pieces sewn to each other. While covering the wing the stitches have been hidden with strips of fabric with zig-zag edges put into place with tightening lacquer to protect the seams.

When scrutinizing the wings stripped of the fabric, we noticed that the stem of the left-hand wing differed in form from that of the right- hand wing. Could it be that the entrance to the Link Trainer is on the left-hand side, therefore “a sidestep” has been made to the wing stem to facilitate entering the Trainer cockpit. We also noticed that the gluing seam in the wing structure had opened in places. These seams must be glued before commencing the covering.

The airframe of the wing and aileron are very well and meticulously done, and also very typical wing structure with spars and ribs. Actually one wonders why the wing has been made so complete, because the Link Trainer’s wings weren’t meant to be airworthy. It would have been easier to construct the wings, if the wing had been made of plate, cut into wing form, as is the case in some Link Trainers.

Before we get to covering the Link Trainer’s wings, we must find a suitable fabric. In this case an ordinary white cotton fabric will do, as long as it has good tightening qualities. So we bought two different kinds of cotton fabric from Eurokangas for testing the tightening qualities (Bed sheet fabric 150 and Satin), whose tightening qualities we now will test with nitro cellulose lacquer. Hopefully one of them will meet our requirements in covering the Link Trainer’s wings.

Photos by Lassi Karivalo except if otherwise mentioned.

Translation by Matti Liuskallio.

The plywood covering of OH-XEA Ressu is under repair

Perjantai 1.12.2023 - Tuesday Club member

Suomeksi

Ressu’s restoration has progressed well in the Finnish Aviation Museum’s restoration workshop. The left wing, ailerons, vertical stabilizer, rudder, horizontal stabilizer, wing struts and tail wheel assembly are all now under work. Maybe we should actually be talking about repairs, because Ressu is mainly in good condition – except the fuselage and vertical stabilizer. Therefore we mainly concentrate on repairing the damages in the plywood covering.

The aim in repairing the damages in Ressu’s plywood covering is to save as much of the original plywood as possible. Where a blow has damaged the covering and the plywood is still a strip which is in one piece, we aim to repair the damage by gluing the strip back into place, using a supporting piece of new plywood. However, if the damage is an open hole, the plywood is shattered, or there is a piece of plywood missing, we will patch the damaged area with new plywood. The latter repairing method is introduced in this blog, using the repair of the damaged plywood covering on the elevator as an example. In all cases the glued seams of the patches are spackled and sanded, and the patched area is painted to the original hue of the painted surface so that the damaged area can hardly be noticed.

The plywood covering of Ressu’s elevator had one larger damaged area to be repaired. The damaged area is located on the elevator’s left-hand end, in the trailing edge side corner. Here the plywood covering has been broken on the elevator’s upper side and on its end. The plywood has broken in several places and parts of the covering are missing. We decided to patch the whole damaged area with new plywood.

First we removed the broken pieces of the covering plywood at the damaged point on the upper surface. Then we drew a rectangle around the damaged area and cut the plywood off along its edges, using a Dremel circular saw blade. This is how we created an opening for the patch on the upper surface. In a similar manner we cut a rectangular opening around the damaged area on the elevator’s end. Now the whole damaged area had been opened for patching.

The next step was to fasten supporting strips on the edges of the opening. The plywood patch will be supported by these strips when it is glued to cover the opening. Some of the supporting strips were glued with strengthening nails to the structure of the elevator. A strip was fastened also on the area where the patches on the elevators upper surface and on its end meet, i.e. at the upper edge of the elevator’s end.

Photo by Antti Hietala.

One of the supporting strips was glued on the underside of the plywood edge so that a little less than one centimetre of the strip was left outside the plywood covering’s edge. Before gluing, the old varnish was sanded away from the underside area of the plywood covering which was to be glued. The supporting strip was glued on the edge of the plywood covering and pressed tight on the plywood with small plastic clamps. The glue we used was Casco Outdoor wood glue.

 

Furthermore, a longitudinal supporting strip was fastened across the opening on the upper side. This strip is needed to support the plywood patch on the opening and make it slightly curved so that it follows the gently curving profile of the elevator’s upper surface.

When the supporting strips had been fastened, patch pieces of 1 mm aircraft plywood were cut for the openings on the upper side and the elevator’s end. The patches were fitted into place, shaping their edges until the patch edges pressed tightly against the sides of the opening.

Photo by Matti Kainulainen.

First the plywood patch was glued into place on the elevator’s end. The upper edge of the patch was pressed against the supporting strip with small clamps and the glued seam on the lower edge was secured with some small nails.

Photo by Matti Kainulainen.

Then the larger patch on the upper surface was glued into place. On the elevator’s leading edge side, the glue seam of the plywood patch could be pressed tight with ordinary clamps. A piece of plywood was placed between the clamps and the glue seam to distribute the pressure evenly on the seam. On the other side of the opening a metal weight was placed on the glued seam to press the plywood patch against the supporting strip.

The gluing of both plywood patches went well. The patch seams were spackled using Plastic Padding’s two-component Chemical Wood. The spackled seams and the whole newly patched area will be sanded before painting. The plywood patches will be painted later, together with several other plywood patches on Ressu’s surfaces.

Photos by Lassi Karivalo except if otherwise separately mentioned.

Translation by Erja Reinikainen.

Priming the HS-4 tail boom stabilizers

Torstai 30.11.2023 - Tuesday Club member

Suomeksi

When both the fabric covered areas of the Mil Mi-8T (HS-4) helicopter tail boom stabilizers had been covered with thin 0,3 mm aluminium offset printing sheet, we could move on to priming these new aluminium surfaces. Obviously, the decayed fabric coverings were renewed with aluminium sheets instead of fabric.

Right hand side photo by Mårten Juslin.

The first phase in priming is to remove grease and dirt from the surface to be painted. KUSTOM-anti grease agent was used to remove the grease. The agent was applied to clean cloth and both stabilizers’ new aluminium surfaces were meticulously wiped with it. The anti-grease operation for other surfaces of the stabilizers will be done in conjunction with the paintwork because their surfaces are already set up for the paintwork.

Photo by Mårten Juslin.

The next step is the graining of the new aluminium surfaces to be adhesion-primed, especially as the HS-4 tail boom stabilizers’ new surfaces are smooth like a mirror.

Photo by Mårten Juslin.

The graining of the new aluminium surfaces was done with a traditional scouring pad. After graining, the graining dust was wiped off the surfaces with a clean cloth. It was noticed that more dirt had accumulated to the cloth used for wiping off the grease and dirt than to the cloth used for wiping off the graining dust. This goes to show, how important part of the priming, the removal of grease and dirt is.

Right hand side photo by Ari Aho.

As a primer or adhesive primer we chose the handy spray paint (Car System Prefill Spray Miranol) and its tone (RAL 7005). Light grey is in this case a good tone for the adhesive primer, because the stabilizers’ undersurfaces will be painted light grey (Light aircraft grey).

Photo by Mårten Juslin.

The stabilizers that were ready for priming, were taken to the painting tent at the yard of the Finnish Aviation Museum. There the primer was misted on the stabilizers’ surfaces as a thin, but engulfing veil. The stabilizers are now ready for the paintwork.

Photos by Lassi Karivalo except if otherwise separately mentioned.

Translation by Matti Liuskallio.

The restoration of OH-XEA Ressu has been started

Tiistai 21.11.2023 - Tuesday Club member

Suomeksi

As told in the previous blog, the parts of the OH-XEA, designed and built in the 1960s by the Hietanen brothers from Turku, will be restored by the Tuesday Club. The aircraft was nicknamed Ressu. Its wings, horizontal stabilizer, elevator, rudder, tail wheel assembly, wing struts and fuel tank have been brought to the Finnish Aviation Museum. We will concentrate on the restoration of its fuselage frame later. When the condition assessment and the restoration plan of the Ressu’s parts brought to the Museum had been completed, it was time to set to work.

The restoration of the wings was started by cleaning the plywood surfaces, painted blue. Both wings were brought to the restoration workshop of the Finnish Aviation Museum. We started the cleaning of the painted wing surfaces with a well-tried method: a magic sponge. Naturally the worst dust was first vacuumed off. The aileron was unfastened to be washed separately. The dust in the joint of the aileron and the wing was brushed off with a paint brush and vacuumed clean.

When using a magic sponge no cleaning agent is used. The tools you need are the magic sponge, a soft cloth, and half a bucket of water. The painted surface of the wing is cleaned by rubbing the surface of the wing, a small area at a time, with the magic sponge dipped in water and squeezed damp. With the soft cloth in the other hand the rubbed area is wiped at short intervals. The magic sponge removes the dirt from the wing surface, and it is wiped off with the cloth, which is rinsed in the bucket. There were also splashes of red paint on Ressu’s wings. Even they could be removed with the magic sponge. The rubbing with the magic sponge does not damage the painted surface unless excessive force is used.

The plywood covered horizontal stabilizer and elevator were treated in a similar manner. We managed to get their surfaces very clean too. We were satisfied to see that after the wash the greyish blue surfaces of the wings, horizontal stabilizer and elevator were as if newly painted. We wonder whether they have been painted in the 1960s using durable Miranol enamel paint as the painted surface has been so well preserved.

For the rudder surfaces no washing was needed, but the covering fabric was removed from the metal frame of the rudder. The covering fabric needs to be completely replaced. A carpet knife was used when removing the fabric. We could see that a strip of fabric had been spun around the outer edges of the frame. This strip protects the fabric which covers the metal rudder frame. On the other hand the covering fabric can be sewn on the fabric strip, but we could not tell whether this had been the case here. The fabric strip covering the edges of the metal frame was removed with a carpet knife. The rudder’s metal frame, stripped of the covering fabric, is now ready for rust removal and the surface treatment after it.

Photos by Reino Aatsalo.

Photo by Antti Hietala.

Three of the Ressu’s four wing struts have been preserved. The struts are surprisingly heavy, so they are probably made of ordinary steel tube. The surfaces of the struts have been painted yellow but are now covered in rust. The surfaces were sandblasted clean. Then the struts were treated with Isotrol varnish which prevents rust. Now the wing struts are waiting for their final surface treatment, and they will be painted yellow as in the original paint scheme.

Photo by Lassi Karivalo.

Photos by Osmo Väisänen.

The restoration of Ressu’s sprung tail wheel assembly was started by disassembling it. Even the tail wheel had to be disassembled so that we will have access to the wheel bearings, which are totally jammed. When the four bolts on the wheel rim had been unfastened, the rusty wheel halves could be wrenched apart by force. When the bearings were visible, we sprayed a lot of rust removing chemical in them and on the rusted surfaces of the wheel rim and left them “to mature” for a week. When a week had passed, we were able to clean the wheel rim halves quite well from rust and the bearings were preliminarily working. The following task will be to repair the sprung tail assembly.

Photos by Lassi Karivalo except if otherwise mentioned.

Translation by Erja Reinikainen.

The condition and damage assessment of Hietanen OH-XEA Ressu and its restoration plan

Sunnuntai 19.11.2023 - Tuesday Club member

Suomeksi

The Tuesday Club is starting the restoration of the Hietanen OH-XEA Ressu aircraft which has been stored at Lemu in the Turku area. The aircraft was built in the 1960s by Ari and Esko Hietanen from Turku. The first phase of the restoration will include the wings, horizontal stabilizer, elevator, rudder, tail wheel assembly, wing struts and fuel tank, which have been brought to the Finnish Aviation Museum from Lemu. The fuselage has no covering, but it remained at Lemu, and its turn will come later.

The first step in the renovation work is to assess the condition of the aircraft and its possible damage. Therefore we took the Ressu’s parts into the restoration workshop at the Finnish Aviation Museum and went carefully through the condition and damages of each part and made preliminary restoration plans for them.

We could see that the plywood covered surfaces of the wings, horizontal stabilizer and elevator are very dirty and have stains of red paint. The damages on the plywood covering are mainly small crushes or holes. However, on the underside of the left wing there is a large area around the registration mark where the plywood covering is badly broken. Or should we say has been intentionally broken – it certainly looks that way. The first phase in the restoration will be to clean the surfaces of the wings, horizontal stabilizer, and elevator and then to repair the damages on the plywood covering.

Ressu's rudder has metal structure and fabric covering, in similar manner as the tubular structure fuselage. The covering fabric is torn on one side of the rudder and a piece is missing.

The rusty metal frame of the rudder can be seen under the torn fabric. The metal frame will be cleaned and painted as it originally was. It seems that the frame has been painted with red Ferrex, the anti-rust paint which was commonly used in the 1960s. The red colour is visible under the rust. We will paint the frame using modern red Isotrol paint.

Finally the rudder will be covered with new fabric and painted pale blue, following the original paint scheme. Red stripes will be painted on both sides of the rudder, following the original look. Number 2 will be painted on the left side and a black bird figure on the right.

Ressu's tail assembly has metal structure and an air-filled tyre. The wheel bearings are completely stuck. We will try to repair the wheel into operating condition. The tail frame will be cleaned of rust and painted yellow, following the original paint scheme.

Ressu’s wings are supported with two wing struts, made of metal tube. Two of them are sturdier, fastened on the brackets on the wing’s front spar, and the two thinner ones are fastened on the brackets on the rear spar. We have both front struts but only one rear strut. The wing struts had been stored inside Ressu’s fuselage frame. The struts have been painted yellow but are now badly covered in rust. They will be sandblasted clean by a contractor and painted yellow as the original ones. We will make a new rear strut to replace the missing one.

The fuel tank is located at the root of the left wing, it has been lowered into place from the upper side of the wing. The fuel tank has dents, and they will be straightened. The fuel tank has had some kind of cap with a rubber seal, there are marks of it left on the wing as well as on the tank. The cap has disappeared. If we can find out what the cap has been like, we will make one. And if we can’t find what it has been like, a good alternative is to make a cap from e.g. 1,2 mm thick aircraft plywood.

The Hietanen brothers have obviously been planning to double the size of the 21-litre fuel tank. We can judge this from the fact that the wing rib next to the tank had already been removed and the wing’s plywood covering had been opened between the wing spars up to the following rib. We will, however, restore the wing structure to its original condition where there is only space between the wing root rib and the first rib for the original fuel tank. This means that the missing rib will have to be made and the opened plywood covering repaired.

Photos by Lassi Karivalo.

Translation by Erja Reinikainen.

Caravelle goes into hibernation

Torstai 16.11.2023 - Ismo Matinlauri

Suomeksi

The days are getting shorter and colder even in Turku, on the south-west coast of Finland. The work period for the autumn has ended and it was time to prepare our beauty into hibernation for the winter.

The last work item for this autumn was to finish the insulation on the cabin walls. On the left-hand side of the cabin wall and ceiling the original insulation material is still there, but on the other side of the cabin the insulation has been dismantled together with the overhead shelves, other interior items, and surface material. We tidied the cut edges of the old insulation material and after analysing different new insulation material alternatives we decided to use cellular rubber, which is available from a hardware store.

It is water repelling, odourless and tasteless, and has a self-adhesive layer on one side. This makes its installation significantly simple and fast. It also acts as a vapour barrier, so no separate plastic barrier is needed, as there is on the inside of the old glass wool insulation layer.

Photo by Puuilo

An insulation thickness of 10 mm is sufficient for our needs, because the aircraft will not be heated in the winter, nor cooled in the summer. The material is sold in rolls, one metre wide, so it is a material which is easy to cut into suitable pieces.

As the airliner has no heating, a solution for controlling humidity had to be found. We discussed the problem with several experts and decided to try two possible solutions.

Ordinary road salt (calcium chloride) was packed into three bags made of fabric, which were hung in the cabin. The salt is a hygroscopic material and absorbs water vapour from the indoor air. Buckets were placed under the bags, and they will be emptied at regular intervals when the salty water drips into them.

We are also testing a small air dehumidifier, which recirculates and cools indoor air, condensing humidity from the air. We set the target and limit value to 60% relative humidity. If the indoor humidity is lower, the dehumidifier switches itself off. When the machine is running, its electricity consumption seems to be 2,6 kWh/day when it is running. This means a monthly electricity cost of 20 euros if the dehumidifier is running all the time.

Furthermore, we have blocked all openings and sealed the doors to minimize uncontrolled ventilation and reduce humidity in the cabin. After the first two weeks we can see that in this period the relative humidity of outdoor air at Turku airport has been 85–95 %. In the cabin the readings have been 62–75 % so we are within the set limits. We will follow the readings during the winter and take corrective actions if needed.

The Caravelle has now gone into hibernation, but we will see if it is possible to wake her up for some Christmas events in December.

Photos by Ismo Matinlauri

Translation by Erja Reinikainen

Covering the DO-5 tail openings

Sunnuntai 12.11.2023 - Tuesday Club member

Suomeksi

The rain covers for Aviation Museum Society owned Douglas C-47 (DO-5) tail openings were finished in October. The tail has been without vertical and horizontal stabilizers and the tail cone for donkey’s years. Due to that rainwater and snow have penetrated into the fuselage. The building of the covers out of aluminium plate has been reported already earlier in a Tuesday Club blog.

A strike force of Tuesday Club members set off from the Finnish Aviation Museum to Turku Airport to fasten the covers to the DO-5 tail at the end of October. The covers and other equipment came along in a trailer. The DO-5 fuselage is on display beside the Caravelle III, restored as Finnair’s “Bluebird” (OH-LEA) in the vicinity of Turku Airport Passenger Terminal. After arriving at the Airport we got the covers made of aluminium plate and other necessary tools and a ladder out of the trailer got on with the job.

We divided into suitable work groups. One of them fastened the ILS look-alike antenna and the thermometer probe we had brought with us for the DO-5. These were fastened in their original places on the undersurface of the nose cone.

Another working duo started to fasten the covers for the openings of the right- and the left-hand side horizontal stabilizers. The third pair concentrated on fitting the covering shields for the tail cone. The fourth pair was tasked to fit in place the covering case we had built to cover the vertical stabilizer fastening point and to fasten in place the shaped hood, made of thin aluminium sheet, to protect the front end of the case and the fixed fuselage fin at their seam.

The fitting advanced rapidly, because the covers made at the Museum’s restoration workshop according to blueprints, settled in place as we had planned. The horizontal stabilizers’ covers were fastened to the edge of the opening at their top edge with stainless steel screws. Holes were drilled through the covers into the fuselage for the screws. After this the cover was fastened to the fuselage also from its lower edge. We used stainless steel screws deliberately, so that they won’t start leaking rusty streaks along the fuselage surface as time goes by. An extra bit had to be cut off from the rear end hem of the left-hand horizontal stabilizer’s cover, to get the cover to press tightly along the edges of the horizontal stabilizer’s opening.

When thinking about the way to fasten the covers, it occurred to us that we could have utilized the existing holes in the fuselage. However, it would have been extremely difficult to match exactly the fastening holes in the cover with the holes of the horizontal stabilizer fastening screws. That’s why we ended up with the above-mentioned method, which produced a few extra holes in the fuselage. If the DO-5 were to be made airworthy, the method would have certainly been different.

The tail without the tail cone was protected with two separate aluminium covers. We had to shape the edges of the upper cover a bit before it clicked into place and was fastened with a few screws. We also had to shape with a hand drill the curved opening in the lower cover, so that we could get the protuberant strip in the fuselage to “pop out” through the opening and press the cover tightly against the end of the fuselage. This cover, too, was fastened with a few stainless-steel screws. The edges of the lower cover shielding the rear fuselage were bent at 10 cm width to an angle of 90 degrees. This way the sides of the cover could be pushed under the covering sheet of the horizontal stabilizer’s rear end and linked to it with a couple of screws.

The vertical stabilizer’s fastening point wasn’t covered with just an aluminium cover, like the other openings, but a nearly three metres long covering case was made for it. The seams of the aluminium sheets were covered with duct tape, after which the case was lifted to place on the low support braces of the fastening point. It was noticed that the case settled in its place as planned. The rear end of the case’s aluminium sheet was bent from its lower edge to form a canopy against rain on the rear end of the fuselage. Despite the case being fairly heavy, it was fastened by its hem with a few screws to the fuselage. Thus not even a strong gust of wind gets to throw it from its place.

Photo by Mikko Jaakkola

Photo by Esko Ruohtula

When the protecting case of the vertical stabilizer’s fastening point was in place, we started work on the final shaping of the hood, covering the joint of the case and the fixed fin. The hood had been bent to its preliminary shape from 0,3 mm thick aluminium sheet at the Museum. We had to shorten it quite a bit before it was the right size to protect the joint. The hood was fastened from its lower edge to the fuselage with a few screws and the sharp head of the hood was shaped round.

Photo by Mikko Jaakkola

The openings for the DO-5 horizontal stabilizers, vertical stabilizer and the fuselage rear end had now been protected against the weather, and we could start the home journey to the Finnish Aviation Museum, satisfied with our work.

Photos by Lassi Karivalo except if otherwise mentioned.

Translation by Matti Liuskallio

Gathering information for future cabin restoration work

Lauantai 11.11.2023 - Erja Reinikainen

Suomeksi

The members of the Caravelle technical design team visited Turku a few weeks ago (on October 25th) to find information for the future restoration work in the cabin. The visitors were Markku Ahokoski, Kari Nyman and Martti Saarinen and team assistant Erja Reinikainen.

All summer and autumn access to the Caravelle’s cabin has been through the right-hand side service door and aft stairway. During the assembly phase in June also the emergency exits over the wing were used. The passenger door on the left-hand side is damaged and it can’t be opened. Lately also the aft stairway has been out of use as its hydraulic pump and cylinders are under repair. The service door is smaller than the passenger door and this has caused problems when large items (e.g. plywood boards) have been taken inside for repairs in the cabin. The passenger door needs to be repaired in the spring before any major work in the cabin is started.

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 roll chains, steel cables and three bungee cords (rubber ropes), several metres long and located in the cargo space under the cabin floor. The mechanism is damaged, and the door can’t be used before the mechanism is repaired. There are no spare parts available so they will have to be made and this makes the repair work a lengthy process.

During their visit to Turku Markku and Kari opened the cabin floorboards and concentrated on the passenger door’s bungee cord system. They also disassembled the broken roll chains and now their parts can be used as models when making new ones. 

While the others were occupied with the door mechanism, Martti was working on the flight deck installing the latest additions into the instrument panel. The panel on the captain’s side looks quite good already, on the co-pilot’s side there are more still missing. Some instruments have been donated, some have been received in an exchange, some have been bought

While the others were working inside the aircraft, Erja dug herself into the storage container to find the cabin seat covers which were brought from Arlanda. According to Murphy’s law, they had been packed into the far corner of the container, in thoroughly sealed boxes which were under other boxes at the very bottom. It turned out that there is a good number of are dark green seat covers in reasonable condition and they can probably be fitted on the seat frames we have. During the winter we can start planning how to clean and repair the seat covers.

Winter is coming and there will be a break in the restoration work for the coldest months. Along with that there will also be less blogs during the winter. 

Photos by Erja Reinikainen

Translation by Erja Reinikainen

Hietanen OH-XEA "Ressu" to be restored by the Tuesday Club

Perjantai 10.11.2023 - Tuesday Club member

Suomeksi

Last year Aviation Museum Society Finland was donated a single-seat experimental aircraft, designed and built in the 1960s by Esko and Ari Hietanen, two brothers from Turku. The aircraft was inspected and registered in the civil aircraft register on August 13th, 1969, with the registration OH-XEA. The aircraft, nicknamed Ressu (meaning Snoopy), is a high-winged, mixed structure single-seat aircraft. The tubular framed fuselage is fabric-covered. The wings, ailerons, vertical stabilizer and rudder have wooden structure and plywood covering. The rudder is tube-structured and fabric-covered.

Photo via Aviation Museum Society, Finland.

Ressu is a small aircraft. Its wingspan is 7,4 m and the fuselage is 5,5 m long. The widest part in the fuselage is the landing gear, with 1,4 m from one end of the axle to the other. In its time, Ressu had several registration marks. First it was registered as H-EA (Hietanen Esko and Ari), then OH-HEA and eventually OH-XEA when it was approved in the civil aircraft register. Ressu’s engine was Continental A 65. The aircraft was removed from the civil aircraft register on January 1st, 1973. We don’t know how many hours Ressu has flown.

Photo via Aviation Museum Society, Finland.

After the flying activity ended, Ressu was stored in several places and its fuselage was badly damaged. Today the fuselage has no traces of the fabric covering and the tubular frame is covered in heavy rust. In the cockpit there is just the pilot’s seat, control stick, pedals, and an empty instrument board. The engine, the instruments from the cockpit panel and the landing gear wheels have all disappeared during the years. Out of four wing struts only three remain. The wings were painted pale blue, the horizontal stabilizer and the elevator have been preserved quite well, there are only some damages on the plywood covering.  The fabric covering of the rudder is broken and the paint on the fabric is badly crackled. The fabric covering on the fuselage has probably been painted pale blue as the wings.

The aim is to restore Ressu at the Tuesday Club to resemble its appearance in 1969 when it was registered. This means that the plywood covered surfaces of the wings and parts of the tail will have to be cleaned and the damages repaired. After that we can consider restoring the fuselage. There the first step would be to treat the rusty fuselage before covering it with fabric. We will try to find instruments for the cockpit if we are able to find the kind of instruments Ressu had. The engine could well be a discarded and inoperative Continental A 65, if we could find one.

Photo by Elias Viitanen.

In autumn 2022 Aviation Museum Society Finland volunteers assembled Ressu in the former shipyard hall in Pansio where the Caravelle III, owned by the Society, was under restoration. Ressu was also on display at the Society’s stand in the Turku Airshow in June.

After that Ressu has been stored at Lemu, in the Turku area. From there we fetched Ressu’s wings, horizontal stabilizer, elevator, rudder, tail wheel assembly, fuel tank and wing struts, and brought them on a trailer to the Finnish Aviation Museum in Vantaa. In the Museum’s restoration workshop the Tuesday Club members have already started the restoration of Ressu’s parts. The fuselage remained at Lemu, but it will probably be taken under restoration next year. The Tuesday Club has now started Ressu’s restoration project which is estimated to take a couple of years.

Photos by Lassi Karivalo except if otherwise mentioned.

Translation by Erja Reinikainen.

Making the lower sheet metal cowling for the Myrsky engine

Maanantai 6.11.2023 - Tuesday Club member

Suomeksi

The VL Myrsky II (MY-14) engine has a lower and upper cowling, made of sheet metal. The lower cowling was built at the Tuesday Club. The cowling was made of 1 mm thick aluminium sheet. The stiffening formers that were fastened on the inside surface of the cowling were made of the same material. The upper engine cowling will be built at the Finnish Air Force Museum, where the main undertaking will be the restoration of the MY-14 fuselage.

Before the 1 mm sheet, cut out of aluminium plate, was started to be formed into the U-form of the lower engine cowling, a female forming last was cut out of sturdy plywood. This forming last works as a model, showing that the lower engine cowling needs a curved shape. The shaping of the sheet was done by mangling the sheet in a mangler with three rollers and comparing the sheet to the forming last at intervals. After the mangled sheet had been made to press itself tightly against the forming last, it had reached its correct form. Next the formed sheet could be tried on the Pratt & Whitney engine used in the Myrsky. The engine was moved into the restoration shop in the Finnish Aviation Museum. We managed to fit it snugly on the side of the engine.

Photo by Heikki Kaakinen.

The lower engine cowling needs several stiffening profile strips to keep it in form. The stiffening strips were cut and bent according to the programming information given at Prolaser Oy. After this we started to fasten the stiffening profiles on the inner surface of the engine cowling. The stiffening strips are fastened by riveting onto the metal casing.

The Myrsky blueprints gave us the exact position of each profile strip on the inner surface of the engine cowling. So we started fastening the profile strips, but not straight with rivets but at first they were fastened in place with 12x3 mm small bolts. The holes for the bolts were drilled on the rivet spots according to the blueprints, and a small bolt was put in the hole to fasten the stiffening strip to place. When all the profile strips had been fastened, the inside of the engine cowling looked a bit like a porcupine, because the nuts of the small bolts were sticking out of the edges of the profile lists.

Now the engine cowling with stiffening profiles was fitted on the engine. The casing still settled laudably in place, so we could start fitting the fastening latches in the top part of the engine cowling. The lower and upper engine cowlings are fastened to each other with openable latches because the cowlings have to come off when maintaining the engine or armament.

Before we started changing the fastening bolts of the stiffening profiles to countersunk aluminium rivets, the outside holes of the bolts were countersunk to suit the flush rivets. The profile strips were riveted, one hole after the other, onto the engine cowling’s inner surface with 8x3 mm aluminium rivets. The riveting was done with a riveting pin and a counter part pressed on the rivet head on the opposite side.

Finally it was checked that the flush heads of the rivets had been riveted flush with the engine cowling surface. Some rivet heads had to be tapped with a hammer flush with the engine cowling surface, so that the outside surface of the cowling was left absolutely smooth after the riveting. The finished lower engine cowling will still be chromated, the same way as all the Myrsky aluminium parts.

Photos by Lassi Karivalo expect if otherwise mentioned.

Translation by Matti Liuskallio.

Constructing the weather shields for the stabilizer openings for the DO-5 (Douglas C-47)

Lauantai 4.11.2023 - Tuesday Club member

Suomeksi

The fuselage of the Douglas C-47 (DO-5) owned by Aviation Museum Society is situated in vicinity of the Turku Airport passenger terminal, close to the Caravelle III, magnificently restored as Finnair “Bluebird”. The DO-5 tail has no elevators or rear cone. That’s why rainwater and snow blizzards have penetrated into the fuselage for years, to play havoc inside. Now we can get rid of this problem when the Tuesday Club has made shields to cover the openings. To build them we visited Turku to measure the sizes of the openings and cardboard templates were made. (see the blog from Sep.21st 23)

Photo by Ismo Matinlauri

When we were starting to build the covering shields, we contemplated, whether we’d build the shields from plywood, or thin aluminium sheet. We ended up with a compromise, where we would build a plywood case covered with aluminium to shield the vertical stabilizer’s fastening point. The openings of the horizontal stabilizers and the rear openings we would shield with aluminium sheets.

Building the vertical stabilizer covering case

The fastening point of the vertical stabilizer is built in such a way that it can’t be covered with a shield alone. That’s why we’ll be building a covering case from plywood, which can just be pressed into place, supported by the fastening point’s 10 cm high supporting brackets. The top of the case will be built from sturdy plywood plate. The sides will be from thin plywood. Because the plywood we use isn’t weatherproof, we’ll cover the plywood case with thin aluminium offset-press sheet, which goes well with the aluminium fuselage of the DO-5.

The construction of the covering case of vertical stabilizer fastening point was started from the top, which duplicates as the frame of the case. To make that we used sturdy 12 mm thick plywood plate. We had to build the top from two joined pieces, because the length of the plywood plate at our disposal wasn’t enough to cover the 240 cm length of the vertical stabilizer’s fastening point.

We cut two pieces of plywood, which were a bit broader than the fastening point of the vertical stabilizer. The pieces were joined with a 30 cm long plywood joint piece. The form of the fastening point was drawn according to the blueprint on the more than 240 cm long case top. After that the extra bits according to the drawing line were sawn off, so that we had the finished piece of plywood for the top of the case.

The sides of the case were made from 3 mm thick aviation plywood. 15 cm broad ”strips“ were cut, using a cutter, from the plywood plate to form the sides of the covering case. A 15 cm broad plywood side shields well the vertical stabilizer’s fastening point. The plywood strips were fastened from their upper side to the side of the roof plywood with 20 mm nails. They were joined to one another with a lap joint, so that the ends of the plywood overlapped 10 cm.

When the vertical stabilizer’s covering case was structurally ready, it was covered with 0,3 mm thick offset printing sheets. From 100x70 cm aluminium sheets at our disposal, we cut off strips that were 1 cm broader than the sides of the case. That way the covering strip reaches a bit past the plywood side forming a “dripping edge”, preventing rainwater from rising into the plywood under the aluminium sheets. The aluminium strips were nailed with 20 cm nails to the edge of the 12 mm thick top plywood edge. The strips were joined with lap joints overlapping about 5 cm. The lap joint will be covered with aluminium tape when the covering case is fitted into place.

After the sides of the case had been covered, the case roof was covered. Three one-metre-long pieces were cut from the offset sheets. The sheets were cut about 5 cm broader than the case roof. This is because the edges of the aluminium sheets will be bent over the roof edge to cover the roof/side plywood joint. As the roof covering sheet had been fastened in place, its edges were bent with gentle beating with a hammer onto the top edge of the side sheets. The overlapping edge of the offset sheet was fastened to the roof edge with a few sheet metal screws. The case covering the vertical stabilizer joint was finished.

To shield the front end of the covering case, there will be a tapered “hood”, which will be formed from aluminium sheet. This hood will cover the joint of the vertical stabilizer’s front part (fin) and the covering case. The hood was made from 0,3 mm thick offset sheet and it was bent into form with a bending machine. The so far oversized hood will be formed to its final shape when fitting the vertical stabilizer covering case to the DO-5.

Making the horizontal stabilizer opening covers

The covers for the DO-5 horizontal stabilizer openings were made from 0,7 mm aluminium sheet. A piece was cut, big enough for both the openings of the horizontal stabilizers. The cardboard template of the openings was fastened on the aluminium sheet with adhesive tape. The outline of the template was drawn on the sheet with a felt pen, along which a billet to cover the opening was cut with a cutter and tin snips. Because the cutter and tin snips left the edges of the aluminium piece jagged and sharp, the edges were smoothed with a file. In a similar way the other cover was also cut using the cardboard template. We presume that the covering pieces we cut, are mirror images and will fit either of the two openings.

At the leading-edge head of the stabilizer opening there’s a fixed pipe for the stabilizer’s anti-ice rubbers’ pressure hosepipe. A hole was cut in the covering shield for the hosepipe. Now we were ready to remove the protective plastic sheets on the covering piece. Any traces of the plastic were washed off with white spirit.

The horizontal stabilizers’ opening covers, cut from 0,7 mm aluminium sheet, are very flexible, so it was decided to stiffen them with strips of plywood. From 3 mm plywood panel about 10 cm wide plywood strips were cut with a cutter. They were glued on the inside of the horizontal stabilizers’ covers using the Sikaflex 221.This way the covers gained suitable stiffness, which facilitates their fitting in place to shield the openings of the horizontal stabilizers of the DO-5.

The tail end covering plates

The DO-5 tail is without the tail cone, so the rear end of the fuselage is prone to rain. The rear end will be covered with two aluminium plates, of which the upper is small compared with the lower one. A template from cardboard we had made was placed on the 0,7 mm aluminium plate and the outlines of the templates were drawn on the plate with a felt pen. Covers for both of the rear fuselage openings were cut from the plate. The edges were smoothed with a file. A curved slit a few mm wide had to be made to the lower shield, through which a solid protuberance on the fuselage “peeps” out. That slit was made by drilling a hole to the end of the slit and then drilling the slit open with a keyhole saw.

The covers for the vertical and horizontal stabilizer openings, as well as the rear fuselage, were ready to be fitted to the fuselage of the DO-5. The fittings will be completed yet before the winter sets in.

Photos by Lassi Karivalo except if otherwise mentioned.

Translated by Matti Liuskallio.

How to Fence a Caravelle

Keskiviikko 1.11.2023 - Ismo Matinlauri

Suomeksi

Since the beginning of June, the restored Caravelle has been protected at Turku airport by temporary rented fencing – providing only rather moral security. On Tuesday October 24th the permanent fence around the aircraft was completed. Fortunately during these months before the real fence was built there were no damages or accidents caused by the lack of proper fencing.

Photo by Ismo Matinlauri

When the Caravelle’s location was planned in the Turku airport area, it was already obvious that a fence must be built around the aircraft. The main worry were vandals, graffiti sprayers and odd curious visitors. Secondly the fencing helps to control visitors and in other times protects the curious passers-by from accidents in the vicinity of the aircraft.

Naturally the fence will not stop the most persistent trespassers, but it will, however, provide sufficient security.

The purchase of the fence material started already before the Caravelle arrived in Turku. In spring 2022 Aviation Museum Society Finland bought the material for the fence and the gates. First the construction of the fence was scheduled to take place before the aircraft is moved to the site in spring 2023. Soon it was discovered that the fence will hamper the crane operations on site during the assembly and also make the actual assembly work more difficult. Therefore it was decided that the Caravelle is assembled first, and the fence is erected after that.

The construction of the fence was left to a professional – that means that a contractor was hired to erect the fence. For cost saving reasons some of the work was done by the Aviation Museum Society Finland volunteers. In this case this meant assisting in setting the fence poles into concrete and in spreading the net wiring between the poles. This reduced the total cost nicely.

Building the fence was an efficient procedure, completed in five workdays:

• Day 1: marking and levelling the fence line, digging the holes for the concrete foundations,
• Day 2: setting the posts into concrete, 50 – 200 litres of concrete was poured into each hole,
• Day 3: drilling the bases for the fence posts on the rock slope behind the aircraft and landscaping the concrete foundations,
• Day 4: fastening the wire net on the gate halves (two 5 m wide gates) and making preparations for fastening the wire net,
• Day 5: unrolling the wire net and fastening on the posts, installing the gates and checking their operation.

Photo by Janne Salonen

Photo by Janne Salonen

Photo by Ismo Matinlauri

Photo by Jouko Tarponen

Photo by Jouko Tarponen

Building the fence in late October was eventually a good thing. The weather is getting cold and there is quite a limited amount of work which can be done inside and outside the Caravelle due to the cold and wet weather, so we had plenty of time to assist in erecting the fence.

Mil Mi-8T (HS-4) helicopter tail boom stabilizers' covering with thin aluminium sheet

Sunnuntai 29.10.2023 - Tuesday Club member

Suomeksi

The tail boom stabilizers’ covering of the Mil Mi-8T helicopter, situated in the Karelian Aviation Museum, has started briskly. As was told in an earlier blog about the HS-4, the stabilizers will be covered with a thin aluminium sheet, instead of covering fabric. This is because the aluminium sheet stands much better to weather. And we must remember that HS-4 stands outdoor at the Museum yard most of the time and it’s not airworthy anymore.

The covering of the stabilizers got really started after they had been stripped off tattered and rotten fabric and the faded aluminium surfaces were ground and waiting for painting after covering.

We decided to start the covering from the underside of the right-hand stabilizer. The covering will be done with 0,3 mm thick aluminium offset-printing sheets that were donated to us. Because one printing sheet isn’t enough to cover the whole area, both sides of the elevator will be covered with two aluminium sheets, joined to each other with edge joints.

We drew the area to be covered from the stabilizer stem and tip onto cardboard and cut the cardboard with a cutter to serve as models for the stem and tip aluminium covering sheets. Then we put the cardboard models on the aluminium sheets and attached them to the sheet with tape. This way the cardboard models stuck to the sheet when the aluminium sheets were cut to form with a cutter.

The edge joint of the stem and tip sheets is made on the centre rib of the stabilizer. Therefore a 5 cm wide aluminium support strip was riveted on the rib. The edge joint of the aluminium sheets will be placed in the middle of the support strip and the sheets will be riveted into the strip at the edges. Now the covering sheets could be placed on the stabilizer to their final form. The edges were formed, however, in such a way that the sheets are equally wide at the joint and their top edge joins tightly with the edge of the steel reinforcement on the surface of the stabilizer.

When the underside sheets had been shaped into place, the riveting was commenced from the tip sheet. The sheets will be riveted to the stabilizer at their outer edges with 3,2 x 6,0 mm blind rivets or pop rivets. First the places of the rivets were marked with a pen at three cm intervals at the edges of the sheets. Then the marks for drilling the rivet holes were snapped with a spike. The drilling took place with a 3,2 mm bit.

After the holes on one side were done, the pop rivets were riveted in place one after the other. The rivet was tightened with rivet pliers through the covering sheet into the structure of the stabilizer. After the stabilizer tip sheet had been riveted at its edges to the stabilizer underside, the stabilizer stem covering sheet was riveted to its place.

Because the aluminium sheets were only riveted at their outer sides, the contact surface of the rib and aluminium sheet was seamed with silicone. That way the aluminium sheet glues itself to the rib and won’t resonate in strong winds.

After the undersurface of the right-hand stabilizer was covered, the upper surface covering could be continued in similar manner. The procedure will be the same, when covering the left-hand stabilizer of the HS-4 tail boom with thin 0,3 mm thick aluminium sheet. When both stabilizers have been covered with aluminium sheets, it’ll be time to move on to the painting phase of the stabilizers, and that, as Kipling put it, is a different story.

Photos by Lassi Karivalo.

Translation by Matti Liuskallio.

MY-14 rear fuselage covering

Sunnuntai 29.10.2023 - Reino Myllymäki

Suomeksi

The rear fuselage plywood covering of the three fuselages (MY-5, -9 and -14), which were at the disposal of the VL Myrsky II restoration project, has completely disappeared, so the MY-14 received a completely new covering.

The MY-14 belonged to the so-called main series (Myrsky II) and the blueprints for its rear fuselage have disappeared. The early blueprint of the prototype (Myrsky), the test series (Myrsky I), and the early main series, used for the MY-5 and MY-6, has been preserved. According to it, the rear fuselage has been covered with 1,2 mm shreds of diagonal plywood joined with scarf joints.

By examining photographs a means of covering used in later main series aircraft was found. There seven diagonal plywood sheets were used, with grading in the horizontal seams.

Because diagonal plywood isn’t available, we made it by joining together plywood sheets sawn into triangular shape and glued with scarf joints. The sheets obtained in this way were roughly sawed into shape and then fitting them to final measurements. Gluing was done with Gorilla Glue and the necessary pressure was obtained by using stretch film, clamps at the edges and staples in other places. Originally the staples were used at 20 mm partition.

For the first plywood sheets the inner painting was done after the gluing, but the last ones had to be painted before gluing. In the latter case the patches to be glued were drawn on the plywood and only the areas between the lines were painted beforehand. After the gluing the remaining areas were painted, if possible. The used paint was Temalac by Tikkurila and the shade was RAL 7005.

External priming was done according to the original advice with alkyd primer, where about 50% aluminium powder was added to the first layer. After this the fuselage was painted twice over with the same paint but without the aluminium powder. Between the coats of paint the surfaces were given primary sanding and puttied where necessary, using Spakkeli which is the Tikkurila wood putty. As a primer Futura 3-solvent thinned primer, shade RAL 7005 was used.

The blog is based on the report and photographs produced by the Finnish Air Force Museum restoration group.

Translation by Matti Liuskallio.

The MY-14 sliding canopy

Tiistai 10.10.2023 - Reino Myllymäki

Suomeksi

The original sliding canopy of VL Myrsky II MY-14 has disappeared. However, we had at our disposal two original but badly corroded sliding canopies with all their parts remaining. The plexiglass parts were, however, destroyed.

The sliding canopy which had been chosen to be restored was taken apart and we noticed that total corrosion hadn’t taken place. So the canopy frames were sandblasted and painted grey. The bearings of the sliding mechanism were replaced with bearings of original quality. For some reason the sliding mechanism didn’t work with the new bearings before the outer rim of the bearings was honed slightly narrower.

The locking peg, which moved inside the canopy frame, was rusted solid and the wire moving the peg was cut off. The old locking peg was removed and replaced with a new one, lathed according to the blueprint. A reinforced peg was made, according to modification amendment C 301, because the original peg in the frame was of that model and the locking slots in the runner were measured for the reinforced peg.

The wire inlet/guide piece was in a poor shape and was replaced with a new one, made of parkesine according to the blueprint. A new wire was soldered to the locking peg and an end piece was made to the wire according to the blueprint, and a piece of rubber hose, which worked as the handle was attached with brass string. The original lever for the opening mechanism, cast in brass and the aluminium press button at the end of the lever were cleaned, and the lever was painted grey, the press button black. The “PRESS”-text engraved at the end of the press button was nearly vanished. The engravement was repaired where needed and the text was painted white.

The new bent canopy plexiglass panes were sawn into measure and the necessary rabbets were milled and ground, so that the panes settled flush with the canopy frame strips. The original inner plexiglass aluminium holder strips were cleaned with oxalic acid and painted grey. The plexiglass panes were fastened with new 3 mm screws and nyloc nuts. A suitable hole was made into the canopy’s top plexiglass pane to give access the opening press-button.

The original aluminium strip at the rearmost end of the canopy was badly corroded and broken, so a new strip of 0,7 mm aluminium plate was made according to the blueprint. According to the blueprint there should be a seal made of felt at the front end of the canopy, but according to photographs it seems that it has never been fitted there, so we left it out, too.

The blog has been edited from the report by the Finnish Air Force Museum’s restoration group. Photos by the Finnish Air Force Museum.

Translation by Matti Liuskallio.

The Finnish DC-Association's DC-3 visited Turku

Sunnuntai 8.10.2023 - Ismo Matinlauri

Suomeksi

On Wednesday, October 4th, the Caravelle restoration work was interrupted in a very positive way: The DC-Association’s Douglas DC-3 OH-LCH landed in Turku and taxied to the airport terminal.

We can say that “the flying eternally youthful visited the new senior”. The DC-3 was in Turku on a training flight and the crew came to see how the Caravelle’s restoration work is progressing.

The crew members who visited the Caravelle: pilot Mikka Rautakoura, maintenance director Jussi Pakarinen, mechanic Reino Ahola and chief pilot Petri Munukka.

There was a lively conversation in the cabin and on the flight deck about the technology used in the Caravelle. The visitors were particularly interested in how the acquisition of the flight instruments for the instrument panel is progressing.

Photos by Ismo Matinlauri

A brief update on the restoration work: This week we installed the last new plywood boards into the floor and now the necessary areas have been replaced. Four boards of 12 mm thick waterproof plywood were needed, but now the critical areas of the floor are in good condition.

We installed a sheet of thick plexiglass in the cabin floor area above the wing-fuselage joint. In the future the visitors are able to see the details of the wing-fuselage joint.

Outside the aircraft the polishing work on the fuselage has also progressed. The polishing of the front section will be completed before the autumn rain and cold weather settle in. During the following two weeks a permanent fence will be built around the aircraft. That will be the topic in the blog at the end of this month.

Photos by Jouko Tarponen except if otherwise mentioned.

Translation by Erja Reinikainen. 

Making a look-alike ILS-antenna on the DO-5 nose

Sunnuntai 8.10.2023 - Tuesday Club member

Suomeksi

Last spring the missing lower part of the nose cone was made of glass fibre to the C-47 (DO-5), owned by Aviation Museum Society Finland. To make the nose appear real, it should include an Instrument Landing System glidepath antenna. It consists of the antenna arch, made of 10 mm thick aluminium tube, a vertical support in the middle of the arch, the antenna stem shields, a base plate, a wedgelike form plate and a rubber seal. With the aid of the form plate it’s possible to fasten the antenna tightly and at the right angle on the curved surface of the nose cone. Both ends of the antenna arch penetrate the stem shields, reaching the underside of the base plate, where at both ends of the antenna tube there’s a connector for the antenna’s electric wire.

We don’t have this antenna to fit on the DO-5. So we decided to make a look-alike copy of the antenna, because the DO-5 will not be made airworthy. We were lucky to get an original antenna for making the look-alike copy, although it is without the form plate made of cork and the rubber seal belonging to the antenna. At the same time, however, we got a broken base of the antenna to be used as model, on which to make the look-alike copy. The base still had the form plate and the rubber seal in place. We are obliged to return the form plate, so it, too, has to be done.

Picture by Reijo Siirtola.

To make a look-alike copy we made a model drawing, which is on the outside looks like the original antenna. The difference from the original antenna is that we replace the original antenna made of aluminium tube with a solid 10 mm thick aluminium bar. The fastening of the antenna arch to the base plate also differs. Because our antenna will not be functional, we’ll fasten the antenna arch to the base plate with nuts. For that purpose the ends of the antenna arch will be pushed with their shields 10 mm past the underside of the base plate and the ends will be threaded for the nuts. We’ll have to make a new form plate, too. We’ll make it out of mass plate that can be reshaped, instead of cork.

Photo by Reijo Siirtola.

We started making the look-alike antenna by dismantling the antenna base we had. The antenna end shields, made of hard plastic, which were attached to the base plate with small screws, were broken. They were mended with epoxy putty. After the putty had dried, the shields were formed to their original shape and painted black. At the same time holes were opened through the shields, to enable the ends of the aluminium rods, modelling the antenna arch, to be pushed through the shields.

Photo by Juha Veijalainen.

To make the antenna arch, we cut an overlong piece of 10 mm thick round aluminium rod.  To bend the antenna to its original form, we built a bending device. With it we bent the aluminium rod to the exact arched form of the original antenna. We pushed the overlong ends of the antenna arch through the antenna shields to cut them to exact length. For that purpose we measured from the original antenna the distance from the top of the arch to the surface of the base plate and added the necessary 10 mm, the distance that the antenna ends reached below the base plate. We cut off the extra bits from the antenna arch ends, after which the ends were threaded for the fastening nuts.

To make the vertical support in the middle of the antenna arch, we cut off from 10 mm aluminium rod an also overlong piece for the centre support. We shaped the top end of the rod as concave, for it to press tightly against the top of the antenna arch. We measured the necessary length for the centre support and marked the lower end of the rod accordingly and cut off the extra. The centre support is fastened at the top with a small bolt through the antenna arch and at the bottom end with a small bolt through the base plate.

Then we marked the attachment point for the centre support on the antenna arch and drilled a hole for the top fastening bolt. There’s already a hole in the original base plate for the bottom end bolt. After the holes have been drilled in the top and bottom ends of the vertical support, inside threads were made with a threaded pin, and the vertical support for the antenna arch was ready for fitting in.

A new form plate to replace the original one made of cork had to be made. We made this form plate out of easily workable mass plate. The mass plate was ground wedgelike from the sides. The side against the base plate was left straight, but the side against the nose cone was worked as concave, according to the original model. Finally holes were drilled in the new form plate for the antenna arch nuts.

It was time to assemble the antenna. We pushed the ends of the antenna arch in their shields in such a manner that the vertical support in the middle of the arch settled nicely between the antenna arch and the base plate. We turned into place the bolts to the ends of the vertical support. Then we fastened the antenna shields to the base plate with four small screws through the base plate. That done we tightened the antenna arch into place with the nuts at the arch ends. The vertical support worked as a stiffener when fitting the antenna arch into place. When the form plate with its rubber seal was fitted, the glidepath antenna look-alike copy of the DO-5 instrument landing system (ILS) was finished.

The next thing to do will be to go to Turku and install the antenna look-alike copy onto the upper edge of the DO-5 nose cone’s lower part made of glass fibre. The DO-5 is situated by the Turku Airport Terminal, beside the Caravelle “Bluebird”. We can measure the exact position of the antenna from the original “DAK” nose cone, so according to that we’ll drill the necessary holes into the upper edge of the lower half of the DO-5 nose cone made of glass fibre and install there the ILS-antenna look-alike copy we made. We’ll go and install the antenna still before the winter sets in.

Photos by Lassi Karivalo except if otherwise mentioned.

Translation by Matti Liuskallio.