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Jan 01, 2012, 04:09 PM
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tuootal's Avatar
Build Log

PIK-15 'Hinu', ws 1,5m, Short-kit released...

Hello everyone,

Let me introduce myself, I am regular at Scale Soaring forum and I have done some build logs there. See Petrel, PIK-3c 'Kajava' (2,75m, 5,5m) and PIK-7 'Harakka' (2,7m). In history I have briefly visited here to do Tritle DC-6b.

Today's dish is 1,5m rendition of PIK-15 'Hinu'. It is an Finnish design, part of PIK-planes -line. First prototype was built 1964 and it was designed by Kai Mellen, Ilkka Lounamaa and Jussi Rinta. Original design had only one purpose. It is an glider aerotow plane. PIK stands for 'Polyteknikkojen Ilmailukerho', which directly translated is Aviation Club of Polytechnic. Meaning Helsinki University of Technology @ Finland. There are approx 27 PIK designs, so there are still some designs to build.

There has been couple models of this plane. If you search web you will find plans for similar sized i/c model designed by Dick Sarpolus. Also, there was an kit in Argentina (!) by TNT Models, but I *think* that they are not producing it anymore.

You will find more info of this plane at my website ( There are plenty pictures of existing PIK-15's in galleries and some links to 1:1 build logs in links. If (and I really mean if) everything turns out right I will attempt to kit this design.

This is rather nice looking plane. Original really looks like an r/c model and it has nice character. You can se some pics of original below along with prototype plans.

Last edited by tuootal; Apr 27, 2012 at 01:38 PM. Reason: fixed title!
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Jan 01, 2012, 04:24 PM
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tuootal's Avatar

And here starts build..

This model was originally designed as an 3m i/c-plane for scale soaring events. My pal planned to build it but then there was some delays so .. I liked design so much that I wanted to make an smaller electric one. (I did try i/c-stuff in seventies, but did not like them. So I go with electrics) With some CAD magic 3m basic design turned into 1,5m plane.

This is quite straightforward build. Just basic stick-formers-balsa stuff. Nothing fancy. I aiming this to be in 'light parkflyer'-category. No sheeting etc.

Started today with first side of fuselage. Normal 'keel' structure and formers. I like to overdo number of longerons to avoid dead-horse-effect. Also I wanted to avoid splitting formers so I used slightly thicker sheet for them.

Then to rudder. Just basic stuff.

Jan 02, 2012, 04:36 PM
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tuootal's Avatar

Next episode (1)

And continuing with fuz.

- added formers (& longerons) for other side of fuz
- some sanding... and it is cute as bug's ear!

This fuz is quite wide. Wing does add some visual height, but still it has nice, long lines. These planes were built in aviation clubs and they were sheeted with plywood. That really means that there is no complex curves. Just long, curved sheets.

In ancient times (that is pre-70's) they built 6 of these planes. Now, there is one recent build and another is starting ... For some REAL build log see this link. Pics are well worth checking out. That is as real build log as you will ever see.

Jan 03, 2012, 03:51 PM
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tuootal's Avatar

One wing at time.. (1,5)

Then to wings.

Nothing fancy. As the tip of the day you can taper all wing spars at the same time by tapeing them together. Then just use plane to get to desired size.

Almost all spars in wing are tapering. I think that this is slightly overkill, but the structure looks much nicer. Also wing does taper quite a bit, so using constant size spars would make tip look clumsy.

Jan 08, 2012, 03:55 PM
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Some pics of 3d-model

Just to amuse myself (and you also ) I did some snapshots of 3d-model of fuz. This particular version is lacking lower corner stringers, but apart that it is quite complete.

Jan 08, 2012, 04:31 PM
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wizard of odd's Avatar
Nice work Tuomas!
Feb 05, 2012, 04:18 PM
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tuootal's Avatar

Long delay..

(Thanks Wizard!)


have been a while since last post. I have excuses like work, flu, work, travel, work etc. Yesterday I sneaked to my cave to get something done and got cowl mold progressing.

Then today I did longer session, half a day with new wing centerpiece, tail hinges and some further progress with cowl.

Old wing center design had an flaw which I noticed when assembling plane for first time. The V-form of wing is so drastic that TE of wing protruded from bottom of fuz. This is somewhat difficult to explain, and I know that most modellers have propably left it as is (it was only 5mm anyway..), but I wanted to do it properly. So I cut away section of wing which was 'inside' of fuz and replaced it with new straight part. Now wing has 2 joints, which I still need to strenghten a bit. Now wing 'sits' in acceptable manner.

Cowl mold is not yet done. I need to do front of mold from plywood as it needs to have openings machined open. Balsa would not survive.

Feb 13, 2012, 04:51 PM
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tuootal's Avatar

Finalizing tail

Had to spend some time finalizing tail section. That form is quite complex, but when done then it is quite elegant.

To get everything nice and clean, also after covering I sheeted (or actually put infill between longerons) short section of tail.

Also I did make two short pieces or carbon rod (2mm od) which should keep rudd from separating from fuz.

Pics will tell the story.

Feb 13, 2012, 10:44 PM
‹bung macht den Meister..
Deuce's Avatar
Nice work on a tricky part!

Mar 04, 2012, 03:35 PM
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tuootal's Avatar

this is slow....

Thanks James, this is quite slow build. I have all to busy schedule at work so .. all motivation is needed.

And to next episode ...

Finalized cowl mould. Despite the apparent risk of getting bad surface quality I am attempting to pull cowls with balsa+plywood mould. Partly due the fact that I am lazy. Original Hinu's are club-built planes. So they are not glossy-perfect-finish-things, more like 'this was hammered...'. I am also using 1mm plate so it can tolerate some imperfections.

Got also canopy mould started. Needs plenty sanding etc.

Then after long thought I did wing retaining stuff. I had plenty of options as this is quite easy structure. But still it was puzzle. Anyway, 2 x dowels (6mm) in front, nylon screw in TE. How basic is that?

I tried to attach some pics, but got 500 server internal error? Will have to try again later.

Mar 05, 2012, 02:53 PM
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tuootal's Avatar

And the pics...

Included. No server 500 internal problems today whatevers. Great.

Mar 11, 2012, 02:44 PM
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tuootal's Avatar

Time to do some vacuuming..

Ok, tested form of canopy. It seems to be ok. Surface quality is not stellar, I think that it must be glassed etc. But for everyday use this quality could be ok. Surprisingly good for plain balsa mould.

One thing which is quite funny is that the canopy is rather large for a plane which has mere 1,5m ws. That vac frame is largest which I can fit into our oven.

(pls. note that no wives feelings were hurt doing this .

ps : Did also cowl, but I had no vac-frame for that particular size plate. Have to do one.

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