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        Build Log K&A l39 build

#1 juanjulian Dec 07, 2012 08:08 AM

K&A l39 build
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Probable a few years late since the boom of this plane, but it is my time to build one.:)

Aquired this plane here on rcgroups and is the balsa sheteted foam wings scale version. Not so sure but asume since wings measure 36 inches.

Fan: change sun 10 blade
Motor: pending will like a het 2 w25
Tried this fan and a kontronic 48o-36 and the motor was loading to 90 amps in 4s.

Servos: pending Ken seems to use hs 55, ┐will this be good? They have a nice price. I used some micromdigital metal gear futaba servos in my rbc ta 183 and think they were a overkill.

Retracts: thinking of getting the micro pneumatic landing gear from hobbynking. Won't like to spend big dollars on Map retracts.

Rx: hitec minima or optima 7

Build has started

#2 juanjulian Dec 07, 2012 08:16 AM

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More fotos learning how to upload from ipad


#3 turbonut Dec 07, 2012 01:15 PM

Cool! dotn see a lot of K&A kits built latley..that is the slope wing version. I would set it up with a full flying stab its easy and works great. the stab angle is not good for modern power levels. other than that its a real pussy cat to fly..I like the hs 65mg servos ..

#4 Damage Dec 07, 2012 05:44 PM

Maybe this will give me the impetus to finish mine. It's sitting there in the pre-paint stage, about 95% done.

I have air retracts in mine but would have preferred to use servos as on all my other planes. Also fitted flaps per an earlier thread and put landing lights in the tip tanks.

Watching with interest...

#5 juanjulian Dec 07, 2012 05:55 PM

Turbo nut

Will apreciate more info the flying stab specially position of torque rod.

I'm a slow builder so be patient. Have other projects going along.

Cheers all


#6 BadLemon Dec 07, 2012 10:48 PM

Hi Juan
You got another nice build going will watch with interest, good luck on the build!


#7 Larry Dudeck Dec 08, 2012 08:52 AM

I flew mine (ca 2008) with an old Kyosho 75 mm fan, an HET2W on 3S. Perhaps mine was an early version but the ducting fit the Ky fan perfectly. Needed a bungee to launch, but was a decent flyer. After an "off field" landing that damaged the wing, I made a larger wing that increased the area by 12% and reduced the weight. This change was enough so I could then hand launch the L39.

I'm not sure what ended her flying career but just recently I was cleaning out the work shop and came across the FG ducting and the balsa wing. Tossed them.

#8 juanjulian Dec 10, 2012 04:20 PM

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Working a litle each day. A lot of reunions this time of year.

Glued the plastic intakes to the fuselage with, Goop. Very happy wiht this glue each time I find more uses. The fan duct was also glued with this.

Finished cutting the ailerons of both wings, and sanded the leading edge. Masking tape is my friend when sanding.

Will glue both wing and stop until have the retracts to continue.

Not sure if doing flying stab or the normal elevator.


#9 BadLemon Dec 11, 2012 09:57 AM


Never seen plumbing glue like that before is it use to glue PVC pipe together? Nice work on the L-39 I have a V-1 Buzz Bomb kit from K&A I want to build this winter. K&A makes a nice kit for sure.


#10 juanjulian Dec 11, 2012 11:52 AM

Hi Doug:

This glue is like contact cement but on steroids. The same stuff comes in diferent names: MARINE, PLUMBING, AND GOOP.

It is fuel proof, water proof, and bonds different materials.

Give it a try, awesome glue.

Uses I have found:

Fixing kids shoes, and worn soles.
Rc cars entusiast use them on the wheels

Sealing a fuel tank

Gluing velcro to battery packs

Gluing fiber ducts(it glues to a solid rigid but flexible bond)

Considering using this glue instead of hysol for gluing formers inside composite fuselages(flexible and strong bond). It is a lot cheaper.



#11 turbonut Dec 11, 2012 02:05 PM

Hi Juan, Sorry no pics yet for the stab mod..I have been a bit busy..last week 40 hours at work then 35 hours on the week end with my side work..and still not finnished..With the built up tail it is a bit more work to do the flying stab mod. if you dont you may want to give the stab a deg of positive..

#12 juanjulian Dec 17, 2012 05:40 PM

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Hard to make time to get some work done this time of year.

Will have a rudder ans servo glued to the inside with a opening to one side for control.

Thinking about elevators .......

#13 juanjulian Dec 20, 2012 03:47 PM

Started measuring for the elevator build and found some problems.


You can notice in the picture above.
Any sugestion for fixing it?

I was thinking in using the heat gun and heating the fiber fuselage to fix the problem. Worried of doing more damage than fixing the problem.


#14 turbonut Dec 20, 2012 04:57 PM

Tilted to one side?? you can apply heat or just glue a stiffner inside the fuse and hold it straight

#15 BadLemon Dec 23, 2012 09:43 AM

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Hi Juan

Looking at the picture it looks like the right side of the fuse is higher then the left side. Now this could be just an optical illusion but that is the way it looks to me. If so may be able to fix the vertical fin if yo pull down and align the fuse. But if not I have the same problem with an airworld Me-262 and did what Turbonut suggested and it fixed the problem. I made a jig out of foam to set the fuse in and strap it down. Then I heated both sides of the vertical stab and braced it and let the fiberglass cool. Note this worked for me but I was warned not to get the fiberglass to hot or it will buckle.Then I made a support brace for the v-stab and glued it in and had a cross section support that glued to the fuse.

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