1:3,5 Slingsby t.13 Petrel (5m) build from Williams plans - Page 2 - RC Groups
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Apr 05, 2010, 06:10 PM
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chris williams's Avatar
Tuomas, you don't need a second fuz drawing...once you have removed the half-shell from the plan, the remaining half-formers are added straight to the other side. I don't know if you have the plan instuctions? They are downloadable from this forum...

https://www.rcgroups.com/forums/show...el+plan&page=4
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Apr 06, 2010, 06:09 AM
Horned one
zero-zero's Avatar
Tuomas,

I do not understand why your first idea for the bellcrank did not work. Where did the play come from? I have seen it done before, and used it myself with no problems and no play whatsoever.

Good luck with the build. I received a nice package from the postman just a short while ago and boy does it feel good to get your anxiously awaited toy. may your kit arrive soon, and keep us posted!
Apr 06, 2010, 02:17 PM
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tuootal's Avatar

second side of fuselage plan


Chris,

I do have plan instructions if that refers to silent flight magazine article. I have not gone through fuselage part. But I am not fully comfortable of building 2m long fuselage 'outside of board' (that is, in hand). I do not want to have 2m long banana. Original idea was to split keel longerons to two parts, build 2 fuselage sides and then join them. Same comment applies also to instructions of tail assembly. I opted to build them completely on board.

Now as I have received (yess...) kit it seems slightly over cautious as the longerons are quite thick & strong. Have to think of that again. Most certainly some kind of jig or support is must. Idea of building the second side 'in air' has certainly it's merits. It eliminates the risk of fuselage sides to be different sizes, which is real problem with this size of fuse. Error of, say 5mm, might pass easily only to be shown in planking phase.

Nevertheless, thanks for pointing that out.

Tuomas
Apr 06, 2010, 02:33 PM
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tuootal's Avatar

Play...


Quote:
Originally Posted by zero-zero
Tuomas,

I do not understand why your first idea for the bellcrank did not work. Where did the play come from? I have seen it done before, and used it myself with no problems and no play whatsoever.

Good luck with the build. I received a nice package from the postman just a short while ago and boy does it feel good to get your anxiously awaited toy. may your kit arrive soon, and keep us posted!
Thanks for the comment. Postman arrived today, I'll come back to that in next message.

About the play. It is really rather straightforward. Problem is :
1. the M3 screw has diameter of 2,8-2,9 mm.
2. drill used for making hole in AMT bellcrank is exactly 3mm

That diff leads to play. Also, the ball link whole has some play, but not as much. See pics below.

Normally you would not notice this as the screw gets tightened against belcrank fastening it to the ball link. But in this case the fork structure prevented it. There was some play (0,1-0,2 or so) between fork and ball. The fork was really extremely rigid so tightening screw to level of crimping fork would have propably stripped threads.

Possible solutions could be using drill with size 2,5 or 2,8 and then 'threading' that GF plate. Or adding some kind of shims between fork and ball. But.. I solved it in way described in previous post.

Most propably that play would have increased over the time as the screw threads would have eaten into GF plate.

Tuomas
Apr 06, 2010, 02:51 PM
Horned one
zero-zero's Avatar
Aaaaah... I see, you used a fully threaded screw. Whenever I've done that I used a bolt (partly threaded screw) so the unthreaded part would be the right diameter.

Anyway, I get the feeling this is going to be a very instructive build thread. Thanks for the reply.
Apr 06, 2010, 02:57 PM
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tuootal's Avatar

Yahoo!!


And the kit has arrived. And it is great.

First impressions;
1. it is nicely cut and it seems to match plans quite well
2. there seems to be couple parts which are a tad off, but nothing to be alarmed. I have not yet seen perfect kit. Ever.
3. balsa (& plywood) quality seems to be good. Balsa seems to be equal density, so there are no overly soft and overly hard ribs. Which is good.
4. it is rather complete. Even those tailplane plywood curves were included. Along with those small ply triangles. Strangely I was not able to find root boxes, but they are easy to do.

I am happy.

Regarding the delay, maybe I was just too anxious. Also, it turned not be postman Pat who was the one to blame. It was delivered by DHL.

Tuomas
Apr 06, 2010, 03:01 PM
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tuootal's Avatar
Quote:
Originally Posted by zero-zero
Aaaaah... I see, you used a fully threaded screw. Whenever I've done that I used a bolt (partly threaded screw) so the unthreaded part would be the right diameter.
That is one excellent idea. .. Thanks for that, I'll use that in future.

Tuomas
Apr 07, 2010, 04:30 PM
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tuootal's Avatar

Some progress


Went to shop to check some sheet thicknesses and eventually laid out some formers and thought ; 'what a heck, lets glue some to place' .. and ...

This is too easy & fast.

Tuomas
Apr 08, 2010, 03:14 PM
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tuootal's Avatar

Fuselage flip


Then to other side of fuselage. Decided to go with method advised by CW with minor modification. I used cheap aluminium profile pieces (0,5m long) to construct jig. This is just to keep fuselage straight.

I copied this method from http://www.schneider-modell.at/ (see bautips -> rumpfbau).

Tuomas
Apr 08, 2010, 10:57 PM
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I am also builing the Petrel. I was able to get the 14mm brass tube & steel strip fr.


Quote:
Originally Posted by tuootal
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
Apr 08, 2010, 11:13 PM
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IHAVAWDY's Avatar
No wonder Lowe's was "sold out" of clamps...
Apr 10, 2010, 12:43 AM
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tuootal's Avatar

Some progress


Quote:
Originally Posted by IHAVAWDY
No wonder Lowe's was "sold out" of clamps...
Yes. There is approx 100 clamps in that pic. You really need clamps in this kind of project.

Some progress with the hull .. err fuselage. Planked second side, off the jig, planked rest, glassed inside.



Tuomas
Apr 10, 2010, 04:21 PM
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tuootal's Avatar

Update on rc-gear


First, servos arrived. As advised by CW in many builds I decided to use bog standard servos. Only bling-bling is ball bearings. Othervise std.

On elevator I decided to use 'high power' servo. I guess this is targeted to rc-auto's. Propably it does not know it, so it can live in airplane.

Only thing missing is aero-tow hook servo. For that I will use some cheap & powerful servo. Probably HXT 12k, or similar.

Then back to AMT linkage. 4mm aluminium ball links arrived. It turned out to be wrong part. It does have 4mm threads to pushrod, but for ball link it uses same 3mm as previous part. Also, it is incredibly easy to dismantle, so I will leave it out. I do not want it to dismantle itself in air.

It looks nice, but looks do not count.

Tuomas
Apr 10, 2010, 04:40 PM
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tuootal's Avatar

Small steps


Then back to building board. First, I made wing spars. This was rather time consuming task as I found out that LHS does not carry 19mm x 7mm spruce. So I had to find suitable hardware store and piled up suitable candidates. Then in shop I used bandsaw to cut to near size. Spars taper towards tip so getting 5m long pieces to correct size and taper was not really easy.

Then to today's main event. I wanted to cover rear top part of fuselage with ply. As instructed in build article I made paper template for sizing plywood. When I cut plywood part and tried it to place I understood why CW commented that this is not for faint hearted. That plywood is 142 x 39cm (!!!!). Getting the plywood roll around rear fuselage was real challenge. I did use steam & tape & clamps & clothespins & .... , but this was not easy. Almost like wrestling.

But now it is done. Tomorrow I will check whether I have produced extremely large model of banana or is it straight enough.

As the final step today I glassed front fuselage second time to get it rigid enough.

Tuomas
Apr 10, 2010, 05:12 PM
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chris williams's Avatar
Good Lord, that's quick work, you're making me look positively slow! Please tell me you don't have a day job?


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