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Old Apr 28, 2012, 01:32 PM
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Build log PIK-12 Gabriel, 1:3,2 (5m)

Hi everyone,

It's time to come back to Scale Sailplanes. I was briefly absent with scale electric project (see here PIK-15 'Hinu'). And now it's time to continue with.... a brand new PIK-project. There is an slight possibility of this turning into obsession ..

Today's dish is PIK-12 'Gabriel'. It is two seater primary and intermediate training sailplane. So far it is only two seater in PIK-range. It all started with design competition during year 1952. Competition was won by Ilkka Lounamaa. Model's fuselage was designed to resemble PIK-5 and basic structure of wings was copied also from PIK-5. Only major difference being forward pointing arrow shape which also caused models nickname 'Gabriel'. Model collected several nicknames of which most used was 'bus with 12 seats'. That was caused by upright sitting position and extremely high fuselage.

Model was built and it's maiden flight was during may 1956. It proved to be excellent flier many were built in clubs around Finland.

There is quite tremendous amount of some kind of weird character in this plane. It has looks only mother could love, even Jukka Raunio states in his book (PIK-range planes) that the aesthetics were skipped. It goes even further to explain that designers were in hurry or that nobody cared looks of slow flying training plane.

Anyway, it is quite charming. It has everything, straight wings, forward arrowshape wings, round fuselage section, square fuselage section etc. I have often wondererd whether designers simply did not want to make their minds, should it be sleek or clumsy. So they decided to make it both.

I have loads of pics from this plane in my gallery. There are currently 3 existing Gabriel's. I have pics of two of them (OH-KYC and OH-285). Third one is in storage and I am waiting pics of it.

All in all this will be interesting project. I have no knowledge of any prior modelling attempts. The wing platform might make this challenging flier...

Tuomas
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Last edited by tuootal; Apr 29, 2012 at 12:03 AM. Reason: Correct pic.
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Old Apr 28, 2012, 01:48 PM
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Then to plans

Ok,

to plans. I designed this plane during last autumn, but all kinds of excuses prevented me starting build. Parts have been laying around for half an year so I hope that I have not lost some of them.

Design of this plane has some similarities with bigger PIK-3c and some with my upcoming PIK-16c-project. It does feature similar basic structure of fuselage as PIK-3c with thin plywood shell with balsa/spruce spars. Wings are extremely simple, just basic rib-spar-etc. stuff.

As an new thing (for me) I draw elevator to be in one piece, despite of it's center being buried inside rudder. This is exactly as in original, but in this case it is quite challenging part of design. Elevator is also quite hefty, with elevator-span of 1,25m.

Size is 5m (approx 200") and length is 2m. With wing area of 204 dm2 and assumption of 10kg weight the loading should turn out to be around 50g/dm2. Quite average. Nothing fancy.

Preliminary plans below. Again, if this turns to be good flier I might make an kit of it and then it will be available at www.iwaru.fi.

Tuomas
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Old Apr 28, 2012, 06:25 PM
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Fantastic! watching another great design come to life
Tuomas, which airfoil?
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Old Apr 29, 2012, 12:09 AM
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Quote:
Originally Posted by IHAVAWDY View Post
Fantastic! watching another great design come to life
Tuomas, which airfoil?
Thanks,

Airfoils for wing is good old HQ3.5-12, elevator and rudder is NACA 0009. That wing is rather large, it's root chord is 476mm and it stays the same for inner panel.

Tuomas
ps : I used wrong pic in first message. Now it is corrected, but I really should pay more attention...
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Old Apr 29, 2012, 08:06 AM
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start

Then starts the normal busines

With assembling formers. This plane has so huge fuselage (height is ~0,45m) that I decided to make some of the formers built up. ie. There is upper part, lower part and they are assembled using spruce spars. This was just to conserve plywood. Also this way it is stronger.

Had to cut plan to pieces to make assembling easier. Just using small flat piece of wood and clamps to secure everything while normal PVA glue sets.

Tuomas
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Old May 01, 2012, 01:37 PM
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Then to second stage of first set and first stage of second set. Complicated? No.

Clamps? Yes!

Tuomas
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Old May 03, 2012, 02:07 AM
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you start a new one. lovely plan as usual. MY want factor is high....! I see that you built as a pro. lots of clamps. it's looking good.
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Old May 03, 2012, 02:50 PM
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Thanks Conny, this is rather interesting project as there is number of real challenges ahead. And I am not totally certain everything will work like in movies..

And then to todays Clamping session,

I separated most of liteply-parts for one fuz halve from sheets. It took me while to solve puzzles, but then I managed to assemble at least some sub-assemblies. It has been almost half year since I last looked these plans so ... I found some errors so there is fixing in future also

Tuomas
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Old May 04, 2012, 01:21 PM
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Then towards difficult parts..

Then it's time to do something more challenging. Second subassembly is everything which makes center part of fuselage. That means, connecting wheel to fuz, wing saddles etc.

That task is divided into 2 subtasks, 1) wheel base and then 2) wing saddle. This must be done in couple stages and it will take at least 2 days to complete as there is number of slow drying joints. There are approx 20 liteply parts in this subassembly.

First I corrected one error in parts (F-7c center groove misaligned) and then dry-fitted everything. Working with CAD-designed stuff is really wonderful. Everything fits perfect or in case of error does not fit at all.

Then to actual gluing. Pics will hopefully tell everything. Next is second phase of wing saddle and joining wing saddle to wheelbase. That will be tricky.

Tuomas
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Old May 14, 2012, 11:46 AM
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This is going to be a fun plane to fly. Should do it all. I want one!

I like your use of spruce sticks to extend and reinforce lite ply parts. Did you buy a laser cutter or are you using an outside service provider?

Kent
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Old May 14, 2012, 11:54 AM
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Looking good can't wait to see the maiden
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Old May 16, 2012, 02:42 AM
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Thanks guys,

but sadly no progress report. I was travelling last week and... now I am just going to airport again for next week. After this trip I am supposed to have couple possible building nights .

Tuomas
ps : Kent - long time no hear!
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Old May 16, 2012, 09:54 AM
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I'll try again......

Did you buy a laser cutter or are you using an outside service provider?

Kent
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Old May 17, 2012, 10:36 AM
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oops... I was in a hurry..

I use external service provider, those cutters are too expensive.

Tuomas, now in London
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Old May 17, 2012, 12:36 PM
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Quote:
Originally Posted by Knoll53 View Post
This is going to be a fun plane to fly. Should do it all. I want one!

I like your use of spruce sticks to extend and reinforce lite ply parts. Did you buy a laser cutter or are you using an outside service provider?

Kent
i want one to. +1 for reinforce parts. carbon maybe.

tomba
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