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Old Jul 29, 2014, 10:10 PM
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Tony Audsley Retired Locksmith
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Cri Cri

You can blame this on my good mate Loco1 ... thanks Kev

Thought it would be good to have a play with a fun one for a change after the Mosquito ... although I do seem to sometimes run into problems with the "fun models"

Anyway, here goes nothing ... any interest on this one?

Anyone with any experience with the Junkers style flap / aileron please jump in with some advice / help / comments

I did a search and it seems no one has done a scratch build of this one

Quite a bit of info around on this one … Only difference, I will be designing the “electric” version of it as shown in the pics below

http://www.flight.cz/cricri/english/...escription.php

http://www.cricri.zoomshare.com/6.html

Lockey
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Last edited by Lockey; Jul 29, 2014 at 10:31 PM.
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Old Jul 29, 2014, 10:53 PM
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A truly unique project, Lockey!
Will you have a bit of dihedral as seen in the pictures?
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Old Jul 29, 2014, 11:02 PM
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Tony Audsley Retired Locksmith
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Quote:
Originally Posted by djacob7 View Post
A truly unique project, Lockey!
Will you have a bit of dihedral as seen in the pictures?
Thanks dj, I will be building it as close to scale as possible, the full size one has 4 degrees on each wing ... this is what I will be doing

Does anyone know if there is a "minimum" distance you can have between twin props ? if I go with 8" props, they will be fairly close together (about 40 - 50 mm between)

Lockey
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Old Jul 30, 2014, 02:28 AM
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Build straight - Fly twisty
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My neck-top computer says that 40 to 50 mm will be plenty for the prop clearance.
For aerodynamic reasons I would have the prop tips traveling downwards as the pass each other.
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Old Jul 30, 2014, 03:33 AM
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What sort of span you thinking of Tony?
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Old Jul 30, 2014, 04:04 AM
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Tony Audsley Retired Locksmith
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Quote:
Originally Posted by Whiskers View Post
My neck-top computer says that 40 to 50 mm will be plenty for the prop clearance.
For aerodynamic reasons I would have the prop tips traveling downwards as the pass each other.

Thanks Whiskers

Quote:
Originally Posted by Loco1 View Post
What sort of span you thinking of Tony?
Was working on a HUGE 1/4 scale Kev ... which works out about 1250 mm (actually 1225, but I added a bit for good measure)

Lockey
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Old Jul 30, 2014, 06:23 AM
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Tony, as always I look forward to your fabulous results.

Decades ago, I and a buddy worked out Junkers-style flaps for a sport flyer; balsa built up 500 sqin wing, about 4.5-5 lbs, K & B .40 power. They worked, rather well even, but not noticeably better than "standard" flaps on nearly identical model. We believed the extra design/construction effort was not rewarded by improved performance. Further, our one attempt at Junkers-style ailerons (outboard 1/3 of wing half) induced twisting. We also believed the reinforcing added to prevent the twist negated any gain in efficiency.

An major improvement/advantage the Junkers-style surfaces offer is the reduction in controlling force necessary to move the surface. I don't believe we can utilize this advantage in RC. However, you may well find a way!

TonyS
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Old Jul 30, 2014, 06:39 AM
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Tony Audsley Retired Locksmith
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Quote:
Originally Posted by tonystro View Post
Tony, as always I look forward to your fabulous results.

Decades ago, I and a buddy worked out Junkers-style flaps for a sport flyer; balsa built up 500 sqin wing, about 4.5-5 lbs, K & B .40 power. They worked, rather well even, but not noticeably better than "standard" flaps on nearly identical model. We believed the extra design/construction effort was not rewarded by improved performance. Further, our one attempt at Junkers-style ailerons (outboard 1/3 of wing half) induced twisting. We also believed the reinforcing added to prevent the twist negated any gain in efficiency.

An major improvement/advantage the Junkers-style surfaces offer is the reduction in controlling force necessary to move the surface. I don't believe we can utilize this advantage in RC. However, you may well find a way!

TonyS
Thanks for that Tony, might not be worth the trouble then

Do you know if there are any set parameters in relation to the wing ? ... out from the back or distance from the bottom of the wing etc

I was thinking aileron / flaps (flaperons) as on the real one

Lockey
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Last edited by Lockey; Jul 30, 2014 at 07:44 PM.
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Old Jul 30, 2014, 09:49 AM
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Lockey,

Have you seen this 100% scale Cri Cri flying indoors. Mesmerizing!! Best of luck with your project, the Cri Cri is a very cool little plane.

modell-hobby-spiel 2011 - CriCri in Action (2 min 9 sec)
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Old Jul 30, 2014, 10:09 AM
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Tony Audsley Retired Locksmith
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Quote:
Originally Posted by leadfeather View Post
Lockey,

Have you seen this 100% scale Cri Cri flying indoors. Mesmerizing!! Best of luck with your project, the Cri Cri is a very cool little plane.

https://m.youtube.com/watch?v=OWI9PhuIRFY
Yes seen it mate, very clever eh

Lockey
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Old Aug 03, 2014, 04:23 PM
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I would love to see you do this one next. I saw that video a couple years ago. Great size at almost 50". Bring on the plans, Mate. Always love your builds. The Cri Cri has some similarities to a Moni , i.e. rectangular wing and a box/ tub style fuse. I've wanted to do a foam Moni someday.
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Old Aug 04, 2014, 07:40 PM
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Tony Audsley Retired Locksmith
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I stalled on this mainly because of the wing and the Junkers style flaperons, I was going to go with a section similar to the real one (top pic)

I have decided to drop the Junkers and go with a std aileron (flaperon) and a Clark Y (ish) style wing section

Any comments or suggestions ?

Lockey
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Old Aug 06, 2014, 09:52 AM
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This one is going to be a Right Side Up flyer anyway, so Clark y is good to go .

Bob
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Old Aug 07, 2014, 06:33 AM
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Tony Audsley Retired Locksmith
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Almost there with the drawings, now for the plans

Lockey
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Old Aug 07, 2014, 05:35 PM
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Good lookin' drawings as usual Lockey!

Dave-
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