Gliders restoration in Finland

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OH-339

Beautiful SZD-9 Bocian at the Flying Museum of Karhula Flying Club. In the background is world’s only airworthy Gloster Gauntlet and a fuselage of Grunau Baby. The Baby is under restoration but it won’t be airworthy.

During the last few decades, interest in old gliders has increased in Finland. Perhaps most extensively restoration of gliders is made at Kymi by Karhula Flying Club. The club has renovated three different models of PIK-7 Magpies, Bocian and PIK-5. These gliders and many others can be seen at Flying Museum of Karhula Flying ClubLakeuden Ilmailuosuuskunta (The Lakeus Aviation Association) is currently rebuilding an old Klemm tow-plane at Seinäjoki. Members of the association have also renovated a number of gliders. Many individual enthusiasts also own wooden gliders in Finland and most of them are renovated to airworthy condition.

 

Ari Saarinen

Ari Saarinen is restoring Mucha at his workshop.

Harri Mustonen

Members of The Lakeus Aviation Association and the fuselage of Klemm.


For the restorers essential and great help has been courses of the Finnish Sport Aviation Institute. These courses have been held around Finland and in the Institute at Räyskälä. Several restorers have learned at courses e.g. wood and metal work, fabric covering, gauge assembly and fiberglass renovating. Without them many vintage Finnish gliders would stay on the ground.

Harri Mustonen

Pentti Saaristo (right) teaches Kimmo Tihula how the fabric is sewn. In this case the wings of the Pitts Special.

Harri Mustonen

Author stitching the wing fabric of PIK-5.

Harri Mustonen

Fabric covering is an essential skill when restoring a glider. Pentti Saaristo has worked for many years as a tutor at the Finnish Sport Aviation Institute courses.


Göran Hollsten

OH-PAC as an a model at Jämi in early ’50s.

Some of the old gliders are restored more some less. The author’s PIK-5 OH-139 definitely belongs to the first group, as all wooden parts of the glider have been rebuild – the only exception being the nose cap. OH-139 or OH-PAC, as it was first registered, was built at the workshop of Jämi in 1947 with serial number 3. It flew until 1967, when it was grounded due the poor quality of glue seams.
The restoration began in 1981 but was canceled the next year. The work truly started after two decades in 2004. It was quite obvious that all wooden part should rebuild. Fortunately most of the metal parts could be used and those which were missing were engineered by professionals.

 

Finnish wooden gliders are made of pine, which is used in spars, and skinned with birch plywood and fabric. The work began with the wings. In 1982 we purchased the main wing spars which were built already in late ’50s at Jämi. As we started the project second time the spars were still in great condition although they were over 50 years old! Wood is long lasting material when stored under appropriate conditions. All what had to do was to build over 40 ribs and install them. After that the plywood of the leading edge skin was glued. Well, it took about four years until wings were complete.

 

Harri Mustonen

Wings under construction in 2005.

Harri Mustonen

Leading edge plywood was soaked in water before bending and glued after they were dried. A wood stick web was used to ensure that the pressure was steady.

Harri Mustonen

The right wing lacquered in 2008.

As the wing frame was ready it was time to build fuselage, which is quite simply in PIK-5. The front section of fuselage consists of ten frames and several pine spars. The fuselage was assembled upside down over a solid table. Plywood skin was pressed with staples and clamps for gluing.

 

Harri Mustonen

Fuselage under construction in the spring of 2009.

 

Harri Mustonen

Plywood skin is pressed with staplers, nails and clamps during gluing. As an adhesive was used Araldite epoxy.

Harri Mustonen

The fuselage with rudder, horizontal stabilizer and the open canopy is almost ready in winter 2012.

Harri Mustonen

A trial fitting of the horizontal stabilizer (the oars at the workshop’s corner don’t belong to the equipment of PIK-5, even though there is a lot of lakes in Finland).

 

Last wooden parts were ailerons and the horizontal stabilizer. The ailerons were the hardest parts to build as they are three meters long and have a slim structure. After that the rudders, ailerons and wings were fabric covered. At that point the year was 2013. It took a year more before OH-139 was ready to fly and the maiden flight was in August 2014. To rebuild a PIK-5 took a decade… or three.

 

Harri Mustonen

Gluing the skin of the horizontal stabilizer which is made of 0,8 mm plywood.

Harri Mustonen

Ailerons are long and slim and hard to manufacture. The plywood in the leading edge is only 0,8 mm thick.

Tomi Grundström

A trial fitting of the wings is complete. May 2012 Jämijärvi.

 

Tomi Grundström

Roll out at Jämijärvi in the spring of 2012.

PIK-5c OH-139 at the heath of Jämi in 2015.

PIK-5c OH-139 at the heath of Jämi in 2015. The blue nose cap is the only wooden part of the original glider OH-PAC.

Jarno Mustonen

The maiden flight of OH-139 was in the August of 2014.

Harri Mustonen

VGC 2016