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Dec 11, 2014, 05:10 AM
build, fly, crash, repeat ...
Stuart Linfoot's Avatar
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Build Log

HK laser cut kit cub 1180mm build


after a number of years away from building due to life events, I finally settled down, I got me that Laser cut cub kit from Hobby King because I wanted to try my hand at building again

So, I built myself a little hobby room, (with no kids in the house any longer, I got a whole bedroom to myself), I built me a work bench, some hobby storage shelves, sorted out what hobby stuff I had left, and decided to build me that plane.

here's the kit - http://www.hobbyking.com/hobbyking/s...cowl_KIT_.html

it don't come with much either, some laser cut wood, and some instructions that are next to useless and that's it, no hardware, and no plans, but that's what makes the kit low cost, so no complaints here. $25 bucks plus shipping is a good price I think. I don't remember exactly what I paid, (I've had the kit a while) but it seems like it was less then 30 bucks to my door.
Last edited by Stuart Linfoot; Dec 11, 2014 at 02:00 PM.
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Dec 11, 2014, 05:18 AM
build, fly, crash, repeat ...
Stuart Linfoot's Avatar
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the first thing I done was started putting the fuselage together, with no plans to follow, I decided to wing it (no pun intended), I looked all over the internet for some build threads and while I did kind of find a couple, it's seems everyone has a different idea on how to put this together, some ideas were good, some I didn't agree with, so here's my take on the kit.
Dec 11, 2014, 05:22 AM
build, fly, crash, repeat ...
Stuart Linfoot's Avatar
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over the next few days, I kept adding to the fuselage, a little bit at night after work till it slowly started taking shape
Dec 11, 2014, 06:17 AM
The World needs Jesus
Boogie_'s Avatar
That looks like it's going to be a nifty little plane.

Did you take a look at the "files" tab down at the bottom of the HK page? ...down there with the reviews/discussions.
Looks like several mods and how-to's in there.

A flying buddy who wants to try his hand at building has been looking at this kit. I'll gonna tell him to check in on your build.

Looking good so far.


Julian
Dec 11, 2014, 11:34 AM
Which means "what" to me?
invid66's Avatar
I have this same kit, mostly assembled, languishing in my storage unit. I need to bend up some landing gear, find some electronic bits, install hinges on the control surfaces, and do some final sanding and covering.

Seeing you building yours makes me want to fetch mine home and finish it.

Chet
Dec 11, 2014, 02:06 PM
build, fly, crash, repeat ...
Stuart Linfoot's Avatar
Thread OP
Quote:
Originally Posted by invid66
I need to bend up some landing gear, find some electronic bits, install hinges on the control surfaces, and do some final sanding and covering.

Chet
that's my plan for today, I'm going to go to the hobby shop and see if I can match up some gear for it off an ARF, I did order the scale gear off the e-flite J-3 that the cowl came from, thinking I might get lucky, but as you can see from the picture, that landing gear is a bit to big for this plane.
Dec 11, 2014, 02:32 PM
build, fly, crash, repeat ...
Stuart Linfoot's Avatar
Thread OP
one of the problems I've seen in the photos of other HK laser cubs is how people finish the tail fairings for the vertical and horizontal stabilizers. they either leave them out completely, or mock up something that just doesn't look right, so here's what I did.

I started with some light weight easy sanding 1/2 inch square balsa stick, then I made up dummy vertical and horizontal stabilizers, and sandwiched those between the two 1/2 inch square stock and epoxied they square stock to the rear bulkhead at the tail.

then I started sanding, if you pinch the assembly at the rear you can't help but sand in the correct contour, just follow the fuselage angles as you sand, it will come out perfect every time.

one last note - hang onto that dummy vertical and horizontal stabilizer, don't throw it out when your done with this step, your going to be using it during the covering process.
Dec 13, 2014, 10:45 PM
build, fly, crash, repeat ...
Stuart Linfoot's Avatar
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I think I came up with a plan for the landing gear.

after reviewing my options, thinking that I may not be good at brazing up my own, or making my own landing gear, I decided to modify the e-flite J-3 cub 450 landing gear, and I think it's going to work.

the cub 450 gear is actually welded together, it's pretty rigid to begin with, so I decided to cut it in half, cut out about a 1/2 inch out of the center, then sleeve it back together.

I have't soldered it yet, but here's what it looks like so far.
Dec 14, 2014, 12:03 AM
build, fly, crash, repeat ...
Stuart Linfoot's Avatar
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ok, silver soldering didn't go as planned, it didn't stick, I'm going to guess that either I don't have a hot enough soldering iron, (I was using a 100 watt weller type trigger soldering gun, and then I tried a 60 watt pencil iron) or the sleeves I used are aluminum and I should have gone with copper, I'm going to pick up some copper sleeves and try it again, I know I'm on the right track, I just suck at soldering landing gear, but I gotta learn, so I'm going to keep at it till I get it right.
Dec 14, 2014, 06:45 AM
The World needs Jesus
Boogie_'s Avatar
Right, solder won't stick to aluminum.

What type of solder are you using exactly?

Copper tube should do the trick.
Roll up some fine sandpaper into a small stick to clean the inside of the tube.

I'm assuming you're pre-tinning the pieces? and using flux?

Good luck, build is really looking good.
Keep the updates coming.


Julian
Dec 14, 2014, 07:50 AM
Youtube channel : solentlifeuk
solentlife's Avatar
Here's my build review on Wattflyer .....

http://www.wattflyer.com/forums/show...=Laser+cut+kit

One thing I will advise ... this model does not like being hauled of the deck. She needs to be coaxed into the air ...

I use a 3S 1800 - 2200 pack .............

2826 1400kv motor

http://www.hobbyking.com/hobbyking/s...dProduct=12920

7x5 prop
30A ESC

The recc'd set-up - I didn't feel comfortable with ...

Nigel
Latest blog entry: Difference of Forums
Dec 14, 2014, 03:46 PM
build, fly, crash, repeat ...
Stuart Linfoot's Avatar
Thread OP
Quote:
Originally Posted by Boogie_
Right, solder won't stick to aluminum.

What type of solder are you using exactly?

Copper tube should do the trick.
Roll up some fine sandpaper into a small stick to clean the inside of the tube.

I'm assuming you're pre-tinning the pieces? and using flux?

Good luck, build is really looking good.
Keep the updates coming.


Julian

this is the solder I'm using https://www.commonsenserc.com/produc...oducts_id=3372

I'll clean up the joints to be soldered with rolled up sand paper.

i didn't pre-tin, but see I should have, I pre tin when I solder wire, should have done it with this as well, I used flux, brushed it on, got the parts covered real good, or so I thought.

I'm going to pick up some copper tube, and try it again.

I also just oreded some stay-brite silver solder and liquid flux off ebay as suggested by pat tritle through one of his soldering write ups



Quote:
Originally Posted by solentlife
Here's my build review on Wattflyer .....

http://www.wattflyer.com/forums/show...=Laser+cut+kit

One thing I will advise ... this model does not like being hauled of the deck. She needs to be coaxed into the air ...

I use a 3S 1800 - 2200 pack .............

2826 1400kv motor

http://www.hobbyking.com/hobbyking/s...dProduct=12920

7x5 prop
30A ESC

The recc'd set-up - I didn't feel comfortable with ...

Nigel
thanks for the link Nigel, I'm going to read up on your build, see if I can learn something new.

the motor I got for mine is the turnigy SK3 2826 1130kv, thinking that it would be just enough to fly it scale, without any access power, if it don't have enough power to fly the plane, I can easily upgrade it to the 1400kv version. I also have a 20 amp eflite esc which I think is a good match for the 1130 kv motor.
Dec 14, 2014, 03:51 PM
Youtube channel : solentlifeuk
solentlife's Avatar
The 2826 1130kv will be fine ... she'll purr on it.

What prop ? 7x6 ? The 7x5 I use on mine will probably work as well ...

My Cub flies on about 1/2 throttle ... and is way over speed when you open up ..

HK J3 Cub Maiden Success 20 Aug 2013 (7 min 56 sec)


Here's another vid ... point to note - that rudder is POWERFUL and you'll see I have 'brain-fade' on take-off and didn't release it quick enough from the cross wind take-off run .. in fact I really screwed up and forgot ! - tried to correct with aileron. We all have our off-days !

Hobby King J3 Cub Laser kit Saldus 24 Aug 2013 (8 min 5 sec)


Nigel
Last edited by solentlife; Dec 14, 2014 at 03:59 PM.
Dec 14, 2014, 04:03 PM
Youtube channel : solentlifeuk
solentlife's Avatar
There is one thing I wish I had done before flying her ..........

Taken a plug of the cowl so I could make more. It's flimsy and splits very easily. I contacted the kit manufacturer - very nice people - but price was crazy for them to send it to me ... higher price than the original kit !! They offered to tell HK to send me a replacement FOC if I bought another of their kits via HK ...

Nigel
Latest blog entry: Difference of Forums
Dec 14, 2014, 04:20 PM
build, fly, crash, repeat ...
Stuart Linfoot's Avatar
Thread OP
Quote:
Originally Posted by solentlife
There is one thing I wish I had done before flying her ..........

Taken a plug of the cowl so I could make more. It's flimsy and splits very easily. I contacted the kit manufacturer - very nice people - but price was crazy for them to send it to me ... higher price than the original kit !! They offered to tell HK to send me a replacement FOC if I bought another of their kits via HK ...

Nigel
the e-flite J-3 Cub 450 cowl fits perfect, like it was made for the kit. that's the cowl I'm putting on mine.

the clear plastic cowl that came with the kit was cracked in half when I got it. if you want it I'll mail it to you, but it is cracked.

I have an apc 7x5ep prop for mine, I can go a 7x6 if needed


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