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Old Mar 04, 2009, 09:31 PM
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Chris Jenkins's Avatar
United Kingdom, Wales
Joined Feb 2005
881 Posts
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Junior 60 Conversion to Electric

Thought there might be some interest in pictures of my solution to the conversion of a Junior 60 to electric. Before starting I did a search of the forum and couldnt find much on this subject, so hopefully it might help others in the future planning this sort of surgery !
The model was part built around 6 to 7 years ago (cant remember exactly) and was destined for a Saito 30 four stroke. Experiences with my electric Playboy Senior convinced me that electric would be the way to go with this model when I came around (finally) to finishing it off.
The nose area has been subject to major survery, and a plywood motor mount and battery box constructed which was grafted into the nose. The old engine bearers were cutt of just after they came through the ply bulkhead at the front of the cabin, and the ply assembly glued to the stubs, and to the former.
The idea has been to get everything inside but with plenty of cooling, and easy battery change out at the field, but still retaining the pugnacious character of the J60 !
I'll post more pictures of the finished model as it progresses. I'm making atempts this time (I've build several of J60's) to avoid any nose weight, so a redesigned tail end construction might be necssary (using less timber). We will see.
Motor AXI 2814/20, battery Thunder Power LiPo 2100mah. 2 degrees dowthrust and 2 degrees right added in at jigging stage.
Lots of sanding left to do ! (better get some more beer in)
Regards to all
Chris
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Old Mar 05, 2009, 01:54 PM
How far in the ground..?
Power_Auger's Avatar
Poulsbo, WA
Joined Apr 2005
580 Posts
Thanks for the Ideas!!!!

Quote:
Originally Posted by Chris Jenkins
Thought there might be some interest in pictures of my solution to the conversion of a Junior 60 to electric.,,,,,,,I'll post more pictures of the finished model as it progresses.,,,,,,,,Regards to all
Chris
Hello Chris,
I'm completely new to these 'ol timers'. Converting a 1939 - 50 inch Sportster to electric. Have Many questions about what to do. Your Junior 60 "looks" very similar in design to my Sportster. Your pics of the motor / cowl area have given me great insight as to what I may be able to do to solve my problems converting from slime to electrons. Thank You.

Please post more pics a you progess.

Ron
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Old Mar 05, 2009, 07:24 PM
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United Kingdom, Wales
Joined Feb 2005
881 Posts
Sportster

Hi Ron,

I don't really know if my solutions are the best, but they seem to have worked OK so far. I think the key is to choose and buy the motor and battery combination early and then work from there using the dimensions these give you.
Frankly, I don't care much for removable cowls, and prefer the open arrangement as on the J60.
As you can see the LiPo slides in at an angle of around 35 degrees to allow it to disappear inside the front end. The motor cables feed through the underside of the ply jig and connect up to the speed controller that is placed behind the LiPo. A picture will explain and I'll post a couple. The theory is to keep all the wiring inside, but with battery change outs at the field "easy peazy"...we will see if it works out !
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Old Mar 06, 2009, 08:09 PM
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Chris Jenkins's Avatar
United Kingdom, Wales
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More Pictures

Ron,

Here are some further pictures. One of the nose area, and then two other general shots of progress. The tranfer linkage down aft is for the elevator (I love these little gismo's), the rudder will be closed loop (pull/pull).

In the nose shot you can see that there is a space between the nose blocking and the bottom of the motor bulkhead...this is for a free flow of cooling air into the battery compartment and thence up and out of the cowl top. Thats the idea anyway. Note from previous shots the cooling holes in the ply battery box, and the 1/4 inch square runners to keep the battery a close fit, but still open to cooling.

Hope this gives some ideas.

Incidently, for general filling during sadding I use bog standard domestic "mix with water" general purpose decoration filler (Polyfiller) and then dribble CA over it once sanding has been done to harden it up to a very solid finish. Works really well...very easy to sand being a powery texture, and once the CA hits it, it becomes rock solid.

Enjoy

Chris
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Old Mar 07, 2009, 02:31 AM
Who said Kiwi's can't fly!
Grunta5's Avatar
Hawkes Bay , New Zealand
Joined Feb 2008
901 Posts
Looking good.. ive a plan for one of these and the later Super sixty... Ive built a couple of Super sixtys but not the Junior as yet.. be neat to see the pictures as this progresses and reports on how it flies...
Grant.
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Old Mar 10, 2009, 05:55 PM
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Chris pdf posted here as per PM.
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Old Mar 11, 2009, 12:55 AM
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Chris Jenkins's Avatar
United Kingdom, Wales
Joined Feb 2005
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Mods

Thanks Pat for the post...and anyone contemplating a J60 can do no better than consider these very neat solutions to the drawbacks of the design and of the ways to improving without effecting in any way the character of the model.

Here are some shots of my solution to the tailplane fixing issue...I like the idea of having a removable tailplane for this model, as it is meant to be taken to to UK this summer in a custom built box. I've used three nylon bolts, with nuts epoxied to ply plates. I might have used countersunk bolts, but these were the only ones I had in the "bits box." This solution works well, and is acutally lighter than the dowel/rubber band method.

I'm sticking to the banded main wings mainly because the construction is too far advanced to change without a headache, but Pat's solution is really nice !

Regards to all
Chris
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Old Mar 12, 2009, 06:58 AM
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United Kingdom, Wales
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Progress Continues

Pretty much finished the tail end, and just the closed loop (pull/pull) to install and the control horns for course...then final filling/sanding and then into covering.
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Old Mar 12, 2009, 01:03 PM
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East Anglia, UK
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I just saw something that worried me..epoxied NYLON captive nut. Pretty sure that would break free in a heavy landing.

Be sure you can reach it later on.
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Old Mar 12, 2009, 06:59 PM
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United Kingdom, Wales
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Quote:
Originally Posted by vintage1
I just saw something that worried me..epoxied NYLON captive nut. Pretty sure that would break free in a heavy landing.

Be sure you can reach it later on.
I hear what you are saying Vint, but I haven't had a problem with this in the past. The whole lot is in compression and the glue is really only stopping the nut from turning during tightening. In fact the bolt normally breaks first.
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Old Mar 12, 2009, 09:58 PM
How far in the ground..?
Power_Auger's Avatar
Poulsbo, WA
Joined Apr 2005
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Bog Standard?

Quote:
Originally Posted by Chris Jenkins
Ron,,,,,,Incidently, for general filling during sadding I use bog standard domestic "mix with water" general purpose decoration filler (Polyfiller) and then dribble CA over it once sanding has been done to harden it up to a very solid finish. Works really well...very easy to sand being a powery texture, and once the CA hits it, it becomes rock solid.
Enjoy
Chris
Hi Chris, you're talking about lightweight spackle right? After the CA hits it, then is it still easy to sand??? Dribble CA over it,,,?

I do have a bad depression on the top of a Top Longeron that needs to be filled so as to get a flat outline. I've cut half the bamboo trees down trying to get it right. Can't seem to get it.

I notice you really do the diagonal bracing correctly. The points are right in the vertex of the angles. Nice work but work.

Ron

edit: What? You mean I should be using BALSA????
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Last edited by Power_Auger; Mar 12, 2009 at 10:21 PM. Reason: A mind is a terrible thing to lose,,,,,,,,,,
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Old Mar 13, 2009, 12:09 AM
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I always use balsa to fill big areas.

Easy enough to slap a patch on and sand back fast with a block.

I only use filler on small cracks.
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Old Mar 13, 2009, 12:45 AM
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United Kingdom, Wales
Joined Feb 2005
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Quote:
Originally Posted by Power_Auger
Hi Chris, you're talking about lightweight spackle right? After the CA hits it, then is it still easy to sand??? Dribble CA over it,,,?

I do have a bad depression on the top of a Top Longeron that needs to be filled so as to get a flat outline. I've cut half the bamboo trees down trying to get it right. Can't seem to get it.

I notice you really do the diagonal bracing correctly. The points are right in the vertex of the angles. Nice work but work.

Ron

edit: What? You mean I should be using BALSA????
Hi Ron...for small dents and dings I use this domestic filler...it dries to a chalky/plaster like consistency which is very easy to sand, but which remains quite crumbly (after all its meant to fill interior plastered walls to take water based paints) . Once all smooth, then a little CA hardens it. I find some of the purpose made wood filler quite hard to work with and needing lots of sanding.

For larger defects then grating in a chunk of balsa CA'd in then sanding down is the way to go, as "Vintage" points out.
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Old Mar 13, 2009, 02:37 AM
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I also use decorator's filler to fill small gaps. Filler is known as "spackle" in the USA. I used to work in the trade. My preferred brand is Tetrion which can be used for outside woodwork. While CA will harden the surface of the filler and allow an iron-on covering to grip, I have had good results using Balsaloc over the filler. Balsaloc is a water-based heat sensitive glue used to improve the adhesion of covering materials. It is painted on and allowed to dry before covering, it's especially good over plywood.

I feel sure there must be American equivalents.
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Old Mar 13, 2009, 11:51 AM
How far in the ground..?
Power_Auger's Avatar
Poulsbo, WA
Joined Apr 2005
580 Posts
Chris, Vintage1, Monza Red, Thanks Guys!

You all helped clear that up. Gave me the proper circumstance to apply each fix. Glad to learn about Balsaloc.
Where I ran into trouble was (right off the bat) cutting the 5 degree angle of the top longeron where it transitions from wing saddle to slope down towards the tail feathers. My surgical skills lack terribly. My miter sander can't handle such a slight angle. Couldn't devise a jig to work correctly
Been around 45 years since I have touched balsa. Maybe I should have left well enough alone?
If it doesn't fly, it will only be my fault. Yet I'm determined to toss it at least
once!
Ron
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