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Old Dec 11, 2011, 04:10 PM
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Peter Rake's 1/5 scale Chiribiri - Prototype build

In response to Pete's solicitation for prototype builds I have decided to take on his 71" span Chiribiri. While waiting for the cut parts from Charlie I have been perusing the plans and trying to find documentation on this plane in preparation for the build. What I have found is not much, not even a single photograph, so I am starting the thread to hopefully get some information on what it actually looked like (color, markings, rigging details, etc.). A 3-view would be great but I may be asking too much.

My other reason for starting the thread is to find a source for some of the building material I will need. Wing construction calls for spruce spars and trailing edge with a 1/4" balsa dowel for the leading edge. Again I am struggling to find these items. Can basswood be used in place of spruce, or should I be looking at hardwood?

Thanks in advance to anyone that can help me out,

Mike
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Old Dec 11, 2011, 06:23 PM
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Subscribed...natch.

I laminate my spars (Titebond) with 1/16" basswood top and bottom, light balsa in the middle. Very strong and light.

Never heard of balsa dowel, but I'm intrigued. I've seen people repeatedly pull wood through a circle knife jig thing to make their own dowel (Roy Underhill comes to mind). Maybe one could do this with 1/4" balsa sticks?

I'll dig around for images, but my first crack was not rewarding.

Have fun with this build Mike!

-Matt

EDIT: Found a bit of info:



Chiribiri 3

Version?

http://books.google.com/books?id=3Ao...rplane&f=false

http://flyingmachines.ru/Site2/Crafts/Craft28939.htm
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Old Dec 11, 2011, 06:52 PM
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Mike,
I couldn't find anything on it either - other than the Walt Mooney plan that inspired my original model. As per usual for the period, clear doped linen, aluminum and varnished wood are the predominant colours. Here's a couple of not brilliant shots of my 45" and 30" models.

Given that I fully expect the rigging to be functional, bass would be fine for the spars. It might even make them more easier to warp. Spruce is only a softwood, so anything similar would also work okay, pine maybe? As for balsa dowel, how are you at sanding 1/4 sq? Hardwood dowel could be used but would make life difficult where it needs to be shaped.

Tail and warp rigging are shown on the plan, the front wing bracing runs from the pylon and the centre point of the axle to, not surprisingly, the forward rigging points on the wings. Four front and rear cables, top and bottom, in total.

Pete
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Old Dec 12, 2011, 12:14 AM
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Thank you Matt for the pictures and Pete for the additional information. It would appear I am being given some creative liberties regarding the final appearance by virtue of the sheer lack of information available. I'm not sure if this is a blessing or a curse since "creative liberties" is quite often the cause of "builder's block" since the goal becomes less apparent and the rethinking process gets in the way of progress. I had hoped to avoid this to expedite the build but I'll have to resolve myself to powering through those indecisive moments and just get 'er done.

Pete,

Great looking models, can't even tell which one is the bigger of the two and the covering on both looks top notch.

In the second pic it looks as if the cockpit surround is bare varnished wood while the aft section is linen covered. This is hard to tell from the pictures Matt has provided so I will be deferring to your expertise on the design practices of the day to confirm such matters.

While I like to incorporate lamitating for its strength to weight ratio, I'm going to try and keep this one as simple as possible so basswood for the spars it is. Regarding the leading edge dowel, since the ribs are specifically cut for a dowel I thought this might be something readily available. The idea of sanding something 30+" long into a consistent round so as to fit into a precut rib sounds a bit daunting. Nothing I can't deal with but I may just notch the ribs to accept a square balsa piece tipped 45 degrees and sand to shape, if you don't object.

I understand how the four front bracings connect to the center point of the axle and the aft outboard rigging is to control wing warp but where does the aft inboard rigging attach below the wing? I hate to be a pest about such things but without reference material you may be getting a lot of questions like this. If your not up to answering them I understand, just tell me to do whatever I want (I'm gonna anyway )
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Old Dec 12, 2011, 12:55 AM
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Mike,
Questions are fine mate. Much better to ask than risk misinterpretting something.

To assist with warping, and avoid needing a really heavy duty servo, I was going to make the extra cables idlers - just from wing to wing, over the pivot points. The only rear cable actually secured to anything other than the wing being the warp cable itself.
The plan shows a relatively crude lower pivot, with the intention of making cables easier to unhook when removing the wings. I was thinking along the lines of fishing snap connector type things, hidden up in the u/c area. Of course, if you wanted to make it warpless (3 channel), feel free. Similarly, if you wanted to refine the lower pivot area, go ahead. Just be sure to photograph anything you change. I was only sort of thinking aloud when I drew it up.

The 45" model, the one with the stained wood sides, was the first design I had published back in about 1996. The staining was just something that appealed to me at the time. In retrospect, I prefer it without.

Strange that, it's usually us that can't get stuff. Balsa dowel and spruce strip are quite common here. Go with your notching and square strip, it doesn't alter anything and probably involves less work than rounding off balsa sticks.

Pete
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Old Dec 12, 2011, 10:45 AM
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Hey Mike, this guy didn't even bother to put ply behind the cockpit (which I think looks odd, and doesn't agree with the 3-views in Google Books).

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Old Dec 13, 2011, 11:22 AM
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Thanks for continuing to dig, Matt. I wonder where that guy found the tail logo detail for that decal. 3-view? You found a 3-view? Where did you find it?
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Old Dec 13, 2011, 03:00 PM
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It's on the photo posted earlier. As is the hinted at dark fuselage colour and rounded cockpit scuttle of the N3.

Pete
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Old Dec 13, 2011, 07:20 PM
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Quote:
Originally Posted by crawlspace View Post
Thanks for continuing to dig, Matt. I wonder where that guy found the tail logo detail for that decal. 3-view? You found a 3-view? Where did you find it?
He probably made it up from the photo above. And the "3-view" was (thanks to my faulty memory) just a single view in the Google book, and upon closer inspection its a "Gabardini" but the other perspective drawings appear to be the Chiribiri.

I like the mystery surrounding this project!

EDIT: Did a little more digging in Italian (see attached for more images of the earlier Chiribiri types).
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Old Dec 13, 2011, 10:27 PM
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Do you have these yet? (I think it's a No. 5)







Here's the translated source (be sure to read the first four pages..they're awesome):

http://translate.google.com/translat...520M%25201.htm
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Old Dec 14, 2011, 12:20 AM
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And by the way Mike, I'm happy to delete all of my comments after you grab whatever images are useful etc.. don't mean to munge up your thread man, just trying to be helpful.
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Old Dec 14, 2011, 12:49 AM
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There appears to be two different aircraft there - one has a twin skid u/c, the other a single skid. However, both seem to be an overall dark colour and both have the rounded scuttle.

Pete
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Old Dec 14, 2011, 12:55 AM
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Quote:
Originally Posted by PETERRAKE View Post
There appears to be two different aircraft there - one has a twin skid u/c, the other a single skid. However, both seem to be an overall dark colour and both have the rounded scuttle.

Pete
GREAT CATCH Pete! The top two showed up in preview when I searched for the "Chiribiri 5" and the other (single skid) was in the article later on, so I'm guessing it's a different version. It just dawned on me that I've been assuming all along your design is for a 5, but perhaps it's more generically Chiribiri without adhering to a specific type, given the dearth of info?

-Matt
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Old Dec 14, 2011, 01:41 AM
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Matt,
It was labelled as an N5 on the Mooney plan and, although labelled as N3, the artist's impression you posted does look the most like it.
That's the one disadvantage of modelling types from this era, unless they're from mainline manufacturers there's very little info about them.

Pete
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Old Dec 14, 2011, 07:57 AM
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Or, if you build like me, it's a blessing, since no one ca claim your flub was actually wrong
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