50+ Build Off - Keil Kraft Robin x 2.5 - RC Groups
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Mar 31, 2016, 04:55 PM
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Build Log

50+ Build Off - Keil Kraft Robin x 2.5


Few flyable weather days, low quality television and copy of the Keil Kraft Robin plan from Outerzone was all I needed to start playing on the CAD for a scale up project.

Initially I was going for 2x and wooden construction, but I have decided on 2.5x and changing the build to depron. I want to keep everything light so it floats along.

The sheet fuselage and fin will easily convert to depron within the original outline. But at a size increase of 23” x 2.5 = 57.5” span the wing was going to need more than balsa spars and depron ribs. So I have chosen to sheet it over with thin depron (within the original aerosol shape).

Here are my CAD doodles… its going to be 3ch RET and electric power.

Thanks to Sundancer for finding the advert below from the January 1963 "Aeromodeller”, to prove it meets the age rule.

This is my second build entry. If the weather turns good then nothing will happen on either build! Based on this weekends forecast, I think I will be able to make a start on something.

Outerzone plan is here

http://www.outerzone.co.uk/plan_details.asp?ID=1390
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Mar 31, 2016, 05:26 PM
I like real wooden aeroplanes!
Sundancer's Avatar
Youare going to keep busy! I'll be interested to see how it works out in Depron. I've posted the entry and build log link.
Apr 01, 2016, 04:53 PM
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SD: Nothing beats carpentry, but I like the challenge of using an alternative material.

Layed out the depron parts and fired up the CNC router to make them. The fuselage sides did not fit on a sheet so I have broken them in two under the wing. So after 3 sheets of 6mm and 3 sheets of 3mm depron, I hope I have got my CAD right.

The ply parts are next, but they will be hand cut once I have printed the templates off.
May 02, 2016, 03:43 PM
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Added the tips to the tail made up from laminated depron. Then sanded the 45 degree angle on them to create a curved tip.

Bevelled the elevator and rudder ready for hinging and rounded the edges on everything.

Wing next...
May 02, 2016, 03:57 PM
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Made a start on the wing.

Added the balsa LE, sub LE and foam LE pieces to the bottom wing sheeting, followed by the bottom balsa spar.

When dry, the depron main ribs and depron webs were glued in.

Getting fed up of UHU Por glue, it sticks to fingers like chewing gum on your shoe. Bring back balsa/PVA building where you can wash your hands.

Washing your UHU covered hands just changes the clear slime into white slime where the soap sticks to the glue.
May 03, 2016, 04:54 PM
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Just a small amount of progress this evening.

Glued the upper spar in place and laminated the wing tip blocks from pieces of depron.

Putting off the job of cutting out the dihedral braces for another night....still happy that a little progress is better than nothing.
May 09, 2016, 02:22 PM
I like real wooden aeroplanes!
Sundancer's Avatar
I have only done a small amount of building with Depron but I have to agree about the UHUpor adhesive; the few times that I have used it I didn't find it pleasant or even particularly effective. Are there any better alternative adhesives for use with Depron?
Jul 15, 2016, 04:34 PM
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Opps, 2 months have gone past without any progress. Strange how quickly the build off time passes if you do not press on with some workshop time. I blame it on all the interesting build threads.....

Hmmm, truth is I got to the point in the wing build where there were a couple of jobs I was not in the mood to work on. For now I have shelved the wing and thought that it was time to tackle the fuselage. Hopefully I will get up a head of steam and get back to the wing issues.

Made a start on joining the spliced fuselage parts and adding various doublers out of 3mm and 6mm depron.
Jul 16, 2016, 02:46 PM
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Made a little more progress today.

Added the dowel reinforcement to the sides.
Bent the UC wire and made a laminated ply pocket in the former for it to slide into.
Added the servo rails (feels like over engineering, as I often glue the servos in these days) and finally joined up the fuselage sides.
Jul 16, 2016, 03:43 PM
I like real wooden aeroplanes!
Sundancer's Avatar
Nice to see bits coming together.
Jul 17, 2016, 04:13 PM
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Thank-you for the encouragement SD.

Only a small amount of progress today due to watching the big toy planes at Cosford LMA show.

Mounted the motor and pulled in the nose and tail formers.
Jul 17, 2016, 09:37 PM
I'd rather be flying.....
JeffMac's Avatar
Looks really nice GS......

best regards,

jeff
Jul 18, 2016, 03:08 AM
So I'M meant to be in control?
Colonel Blink's Avatar
Good progress......... but I'd guess you'll not be needing much of that 140W if you want the wings to stay on...!!
Jul 18, 2016, 05:29 AM
Registered User
Jeff: Thank-you for the support

CB: You are correct that I expect to use the throttle and I'm aiming for 50% cruise. I have used this size of motor (from different suppliers) in many different types of project from vintage, to parkjets and even 3d. It has made my life easy to standardise my equipment and also keep the different sizes of lipo I need down to a minimum - and they are under £10!

Here is a couple of examples of similar projects I have put together using the same power setup and similar depron construction.

36" Quickee, does great rudder rolls and aerobatics
48" Honey Bee - all round great trainer and mild aero's
72" Dragonfly - great cruiser and fun shooting touch and goes.

So at 57", I hope the scaled up Robin should fit in nicely for power/weight.

Off topic, there is more info here:

https://www.rcgroups.com/forums/show....php?t=2066473


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