1:3,5 Slingsby t.13 Petrel (5m) build from Williams plans - RC Groups
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Mar 23, 2010, 01:17 PM
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1:3,5 Slingsby t.13 Petrel (5m) build from Williams plans


Hello world,

I am starting an interesting project and noticed that there is no build log for this beast. It is 1:3,5 Slingsby Petrel type 13 based on Chris Williams plan & Belair Laser Kit Cutting 'parts kit'. Just received plans and spread them in living room. Impressive. Wingspan is 4.95m (194"), weight is 9kg (20lbs).

Some pointers

- Plans from Nexus Plans Services, ordered from here.
- Parts kit from Belair Laser Kit Cutting, ordered from here.
- More info, build article scan, videos etc. here.

The fact that there is no build log here is surprising as the plans have been around since 1999. Only real build log I was able to locate is in Turkey (here). It has excellent pic's, but the language is ... difficult for me. That build is progressing nicely and the quality looks stunning.. My humble goal here is to make some kind of build log in rcgroups and allow everybody to point out errors I am doing :-). I might even learn something. If somebody is in progress of building same plane I do not mind him posting updates to this thread. The more the merrier.

Current status is that I have plans & large pile of plywood. I have ordered kit, but it is still in post. An friend commented my desire to build an scratch vintage scale glider that it will be an 5 year project. Ok, my aim is to finish this before midsummer. But I do not know what year. Not 2010.

I think that the final thought for this kickoff-post should come from the Man himself (Chris Williams, that is..) '... the Petrel is a truly beatiful machine ... altough not a project for the faint-hearted brings its own rewards once completed.'.

I am not faint-hearted so this should be good project for me.

Tuomas
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Mar 23, 2010, 01:37 PM
yyz
yyz
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Tuomas,

This looks like a great project. I'm sure a lot of people will be watching this.

Best of luck,

Mike
Mar 23, 2010, 01:53 PM
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Very exciting, Tuomas!

There's a handful of these now flying in the UK, with a partial build log here...

http://scalesoaring.co.uk/yabb/yabb2...num=1233668026

I expect you've seen Chris W's YouTube clips of his Petrel - also accessible from the scalesoaring website.

It's a big build, but at least you should have plenty thin ply available - I understand most of the world's supply comes from Finland!

Good luck!

Rog
Mar 23, 2010, 06:05 PM
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Tuomas, it has taken a long time for the Petrel to become popular, but now, thanks partly to the Belair kit, and possibly the videos, there have been quite a few built. It is a lovely machine to fly and I wish you many happy hours of soaring flight...
The latest version to arrive in these parts belongs to Allan Boyles and can be seen in this video, if you haven't seen it before. Taken a couple of Sundays ago, here's Steve Fraquet's version, now in it's 3rd season...
THE FLIGHT OF THE GULL-WINGS.wmv (5 min 52 sec)
Mar 23, 2010, 08:39 PM
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subscribed, currently building a 6m version
Mar 24, 2010, 04:57 PM
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waiting for parts kit to arrive, hopefully soon :-)


Thanks for all of your kind words. I do really appreciate your support.

I think that this plane deserves more attention. I have been going though the plans today and it really is straightforward build. There are couple tricky area's like establishing correct wing root position & datum. But normally this kind of challenges sort themselves when that time comes.

It is extremely simple structure. I have built much more complex planes, altough never so large. Just a bit more wood than before :-).

One thing worth mentioning is that this project is extremely economical. Parts kit has modest cost compared to other similar kits. Also necessary strip, planking and sheet stuff is plain basic modelling tech. No moulded carbon parts etc.. Even wing joiner is ancient Graupner 14mm steel slab which I first used in -70's.

Tuomas
ps : yep, we do have good quality plywood here. Just bought 2 sheets (1,55 x 1,55m = 2,4m2 x2) of it for this plane. Gives some kind of perspective.
Mar 25, 2010, 10:03 AM
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Petrels make me wobbly at the knees. Definitely on the must-build list.
Apr 01, 2010, 02:36 PM
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status update


Duh,

this build log is progressing extremely slowly. Current status is still .... waiting for kit. It was supposed to be mailed monday last week. No sign yet.

I beg you all Britons, if you see Postman Pat driving around having Petrel box in his car pls. ask him to bring it here. I am getting edgy. I think it is time to go and fly something.

Ok, I made an fuselage cradle. Some progress.

Tuomas
Apr 02, 2010, 02:09 PM
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Horizontal stab


Ok. I have to admit. I could not stay away from my shop. The magnetic force in plans was just too much. I figured that the short kit propably does not have too much parts anyway so why not start? I think that there is zero parts for horiz. stab, so...

I did slight modifications to make building more straightforward. Also, used collars for fastening piano wire to stab.

Tuomas

ps : it is easter here in Finland, so there is no mail for 4 days.. bad. So there is no way kit will arrive before tuesday. I just had to start.
Last edited by tuootal; Apr 02, 2010 at 02:19 PM.
Apr 03, 2010, 02:49 PM
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Progressing.. to rudder


There are still some parts to do before I have to stop until kit arrives. I decided to continue with rudder. I took an long look to drawings and magazine build. Rudder structure is somewhat complex and I have always disliked those robart style 'stick' hinges.

So I decided to convert hinges to something else. Let's see whether it works. Idea is to replace hinges with GF plates. Piano wire that goes through rudder goes through those plates. See pic's.

I also made some minor changes to the bottom of rudder to make building faster. Replaced balsa sheeting with soft balsa block. Much faster & robust.

Tuomas
Apr 03, 2010, 05:23 PM
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Tuomas,

Thanks for this thread. I'm enjoying it very much, seeing how you tackle the build.

"Subscribed", as I note people say.

Rog
Apr 04, 2010, 09:54 AM
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All moving tail mechanism


Thanks,

And to the next challenge. All moving tail mechanism (AMT) or pendel-elevator needs belcrank. I tried to locate suitable from LHS and online with no luck. This is an 10kg plane so your average graupner piece is not suitable. As I dislike working with duraluminium I decided to make it from GF-plate. Suitable planks were made from 2 x 3mm (inner) and 2 x 2mm (outer) plate. Total thickness is then 10mm. Epoxied with 24h epoxy.

My original idea was to do an 'fork' which could be used to fasten an 3mm ball link. It turned out bad choice, there was play of approx 0,5mm coming from the fact that M3 bolt has diameter of approx 2,9mm or so. The play was in ball link hole and fork holes. Fork is so rigid that it cannot be tightened. This 0,5mm does not sound too much, but the width of tailplane is approx 20cm. So this 0,5mm causes something like +/- 2-3mm play. Which is too much.

Had to think of better way. Ended up with cutting forks away and drilling an near vertical hole for M3 bolt without head. Then epoxing it to belcrank. There was still minor risk of assembly splitting between plates despite good epoxy. To prevent that I added 2 x M2 bolts with nyloc's.

Current solution allows +60/-50mm movement so it is more than necessary. Plans call for +15/-20mm.

Only risk left is the possibility of this M3 bolt breaking. I ordered second set of ball links with M4 bolt. If that arrives in time I will replace bolt, if not I'll try to forget this :-).

Tuomas
ps : Sadly I have to stop this project now. There is nothing more to do before kit arrives. I'll keep my fingers crossed for mail to arrive.......
Last edited by tuootal; Apr 04, 2010 at 12:28 PM. Reason: typos, dämnn
Apr 05, 2010, 04:14 PM
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minor details..


Well, I really cannot keep myself from going to my shop. As I had nothing useful to do I continued on small bits of leftover work from previous days. I finalized AMT mechanism & draw the second part of fuselage drawing. The plans show only one side. I know that it is easy get other side by greasing plan, but I want to keep plans tidy.

As I had spare time I did go slightly overboard on doing the plywood doublers for AMT secondary brass tube. See pics.

Tuomas
Last edited by tuootal; Apr 05, 2010 at 04:28 PM.


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