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Oct 11, 2010, 01:50 PM
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tuootal's Avatar
Build Log

Build log PIK-3c 'Kajava', 5.5m, 1:2.7

Hi everybody,

Following my quite successfull & happy build of CW Petrel I started to wonder what could be suitable next plane. I browsed market and tried to find something 'vintageish' and not too complex. In particular I tried to find plane which could have some nordic angle to it. No avail.

I started thinking that here in Finland we have great heritage of PIK-planes. Most of you propably have heard of PIK-20, some even of PIK-5. It leaves one wondering if there is some cause for those numbers. Yes, there is. They are serial numbers. There are total of 27 (!) PIK-series of planes. And none of them is really currently available as an kit (ok, there is 2 kits around of PIK-20, but I like vintage..). For further info on PIK-planes pls. look here. Also check wiki. Acronym PIK comes from Polyteknikkojen Ilmailukerho. Which translates directly to Finnish institute of technology students flying club.

Nice planes .. but no kit. What to do?

After some negoatitions with PIK, Finnish Aviation Museum etc. etc. and lot of document finding, scanning, etc. I now have full set of plans for 5,5M PIK-3c. Which is one of those nice PIK-planes from 40-60's. The kind support from PIK and Aviation Museum made this project really possible as I had opportunity to use original construction plans and other material. Along with one full size plane. PIK-3c has an nickname 'Kajava' which is vintage name for seagulls.

Current status of project is that I have plans in CAD, all parts are sent to be cut and plans to be printed. So if everything turns out to be right I'll have short kit of PIK-3c here within couple weeks. Which is great...

Construction methods are quite similar to Petrel. Most of structural choices are inspired by great Chris Williams work. Fuselage in particular, which is structurally almost identical to Petrel.

As with Petrel I will make an build log. This time I will do it a bit more detail as I have had couple requests to provide short kit for other builders. Build log will start when I will receive parts etc. Meanwhile I will include some prototype drawings and link to video of 1:1 flying here.

Winter gliding with PIK-3c (4 min 18 sec)

Also, there is great picture resource in one of local aviation enthusiast sites, Flighforum. Pic's are great, but texts are in Finnish. You can't have everything.


ps : I also scaled plans to smaller size (2,74m) version. Did also order parts for it. I have no time for build it soon, but possibly in future :-)
ps : ok, I had to admit, I did also do drawings for PIK-7 'Harakka' and PIK-12 'Gabriel'. And orderd parts for PIK-7. All too easy :-)
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Oct 11, 2010, 03:54 PM
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yyz's Avatar
Very interesting project, Tuomas. It will be fun to follow your techniques and progress. Which airfoils are you using, by the way?


Oct 11, 2010, 04:00 PM
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tuootal's Avatar


Thanks Mike!

Airfoils are almost the same as with Petrel (and many other large vintage planes); HQ 3,5-14 at root and HQ 3,5-12 at tip. I did use Profili 2 Pro to draw all ribs, it saved quite a lot of time. I did also use Dev Fus CAM for fuselage. Those tools are quite nice, once you get an grip of them.

Oct 12, 2010, 11:21 AM
Registered User
Thomas Nelson's Avatar
Looking forward to following your build and seeing how you overcome the various engineering challenges along the way. And thanks kindly for your earlier suggestions regarding an extended motor shaft vs cutting the nose off.

Oct 12, 2010, 01:41 PM
Registered IGG Finland pilot
Hannu Vuorinen's Avatar

Truly inspiring project and inspiring video of PIK also, Tuomas!

IŽll be awating your progress with Kajava, hope seeing it
as fast as your previous Petrell project

Good luck & BR,
Oct 12, 2010, 03:07 PM
Registered User
tuootal's Avatar

thanks everybody. This will be interesting project. It has been a while since I designed anything near this size and I think that I will learn a lot during this build.

However, I did try to plan everything to be as straightforward as possible. No strange materials, no complex structures, nothing fancy. Simple balsa ribs, plywood formers. All parts from your average LHS. Only thing even approaching interesting is wing joiners, which are standard Graupner steel blades. Easily available from LHS, propably not from every LHS.

As said, the structural inspiration came from CW's Petrel. Only this is slighty simpler :-). You see, no gull wings.

Last edited by tuootal; Oct 12, 2010 at 05:22 PM. Reason: typo!
Oct 13, 2010, 12:02 PM
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chris williams's Avatar
Tuomas, did you manage to modify the formers in Devfus to match the full-size..? I have found this very difficult to do unless the fuselage has a simple elliptical cross-section... (This worked out pretty well on my Topaze)
Oct 13, 2010, 12:42 PM
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tuootal's Avatar

dev fus

Originally Posted by chris williams
Tuomas, did you manage to modify the formers in Devfus to match the full-size..? I have found this very difficult to do unless the fuselage has a simple elliptical cross-section... (This worked out pretty well on my Topaze)
Actually that was to most complicated part of whole design stage. I did try several approaches, but in the end I think I managed it.

First - there are those blue squares which define rounded shape, they do not allow you to set 'corners' to form. Insert any amount you wish, but it seems that more you set, worse it looks.

Second - there are those red squares which allow you to set corners. The corners are adjusted using green squares. In plain text:
1. set red square to the center point of corner.
2. green squares appear
3. use green squares to adjust angle of corner.

You also have option to set angles for blue squares if they are first/last of form quadrant.

It is quite complicated thing to explain, but I include two examples which might clarify it. To be able to set those things you have to use edit formers and then use advanced edit. Once you land there it all gets easier. Before that there is no real way anybody could master it.

Hope this helps,

Oct 13, 2010, 04:31 PM
Registered User
chris williams's Avatar
Thanks Tuomas, that's most interesting. I'll have another play with it when I've finished my current project...
Oct 21, 2010, 02:33 PM
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tuootal's Avatar


First two batches of parts arrived. Metric balsa and alu-parts from local cutters. Plywood parts and plans not yet here.

Oct 21, 2010, 04:17 PM
Balsa Builder. With some foam.
ArneHu's Avatar
Cool! In the land of the thousand lakes, you don't need a tow plane to get in the air!
Oct 21, 2010, 08:02 PM
Known Wind User
Martini's Avatar
The PIK-3c is a great looking sailplane!! Thanks for the great video of the 1/1 scale!!

Oct 22, 2010, 03:24 AM
Registered User
Just found this thread.Looking forward to your build.Have been flying a Pik 5 for cuople years myself.

Cheers Colin
Oct 22, 2010, 12:58 PM
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tuootal's Avatar
That 1:1 video is only PIK-3c video which I am aware, these are rather rare birds. Only 20 ever built. Interesting detail is that two of those were built in Canada. There is (poor) picture of C-FUXL in Jukka Raunio's book. Other Canadian PIK-3c was C-FWIP, but I have not found any pictures of it.

Regarding those 1000 lakes, yes, they are nice airfields during winter. But there is an drawback. It is rather cold :-(

Colin, I have read your build log for PIK-5 several times, it is nice plane. Achievement by any standard. Especially that slender tail is structurally challenging.

By the way, did you know that there is an twisted sister of PIK-5? It is two-seater called PIK-12 "Gabriel". I did make some initial drawings of it (ws 5m) during PIK-3c planning stage. It shares some visual aspects of fuselage and the wing is almost direct copy. Although they did make an strange forward twist to it, resulting nickname Gabriel. They claim that it looks like angel in flight. Odd one anyway, like gull-wing with no gull-break. That plane is on my to-do-list for future.

Oct 23, 2010, 06:11 PM
Registered IGG Finland pilot
Hannu Vuorinen's Avatar

Here is photolink to beautifully restored Finnish PIK-5,
I hope IŽll be flying this one next summer


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