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Sep 28, 2015, 01:36 PM
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Build Log

Parkzone Ka8b 2,25m upgrades and graphics


I like to create sailplanes that are different. Started off with a brand new Parkzone Ka8b I bought in San Diego, CA and before I even went aerotowing or flew it, I took the whole thing apart removing all graphics, stickers and paint.

I looked for a distinctive design and created a new set of stickers for the Ka8b depicting a real German registered version.







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Sep 28, 2015, 01:43 PM
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- Start off with sanding all the paint and entire fuselage.
- I reshaped the nose profile to better match the real Ka8b. The lower section needs some additional material. I used filler and cloth with CA glue.
- Cover with lightweight spackle thinned with water, let dry overnight.
(Note: Key is to get the spackle to be like a thick glue. Most of this will be sanded off, you want to be able to fill all the foam pattern).









Sep 28, 2015, 02:16 PM
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Sanding filler and covering with cloth and CA glue


Sanding filler
- Sand white spackle down to a thin layer, just enough to try and hide the foam pattern.



Covering with a fine cloth fabric
I laid down some thin fiberglass fabric for added strength and then laid over some old Ralph Lauren bed sheet with a printed white paisley pattern… , possibly ~300 thread count or so. You can also just use cloth fabric.

- I cut off factory foam hinge and use fiberglass tape to make new hinges or you can also use CA hinges or similar.
- Cut fabric to fit area per side to be covered.
- Spray 3M Super 77 to back of fabric, let tack up a minute or so and then lay down on foam.
- Tack one corner or edge with CA, I started in the upper right of the rudder. This gives you the ability to stretch the fabric while the 3M glue is tacky and make it tight.
- Glue remaining edges when tight, removing any wrinkles.





- Soak fabric and foam with medium CA (I used ZAP medium). Use well ventilated area with exhaust fan or fan.



This is what one side looks like covered with cloth and CA glue.

Last edited by studioRS; Sep 28, 2015 at 02:24 PM.
Sep 28, 2015, 02:30 PM
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Covering the fuselage

- I used fiberglass cloth first, then laid down cloth over. However, you can just use cloth fabric.

- Start at the tail fin and work towards the nose. I covered the tail fin the same method as the rudder.

- Tack down an area, then stretch while the 3M glue is still tacky and remove any wrinkles.

- You might need to re-apply a small spraying to get the cloth to stick again.

- Once the cloth is tacked down and burnished to the foam with the 3M glue, soak the entire fuselage with CA glue in a back and forth motion.





Sep 28, 2015, 02:36 PM
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Covering the nose top section

- This is a little more tricky, but using the same methods of tacking down a corner and stretching the cloth, works really well to overcome the curves.

- Make sure to leave extra fabric that can be trimmed off later with an x-acto #11 blade.






Here is the top section of the fuselage nose after being soaked with CA glue.





Trimmed fabric all soaked with CA glue ready for sanding.



Sep 28, 2015, 02:50 PM
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Mounting Multiplex Aerotow unit into nose

- Pencil in where Multiplex Cularis Aerotowing unit will go.



Drill through nose in this location.







I used a reamer to open the hole to a tight fit.



It doesn't look very nice now, but will later on.

Sep 28, 2015, 03:31 PM
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Create plywood mount for Multiplex aerotow unit

- I used 1/8 birch plywood and cut out a mount to fit the Multiplex Cularis aerotow unit.







- Wrap the plywood and Multiplex aerotow unit with safety wire and fix with CA glue.

! BE CAREFUL NOT TO GET CA GLUE IN AEROTOW UNIT ROD HOLE !

- The aerotow unit fits from underneath and is inserted into the nose from behind. Make sure to carve out foam where needed so that this can be glued in with CA or gorilla glue.

- The plywood will need to be at an angle so the aerotow actuating servo rod can pass through.

- Use CA glue or gorilla glue to fix to fuselage and nose area.

! BE CAREFUL NOT TO GET CA GLUE IN AEROTOW UNIT ROD HOLE !

Use grease first on servo rod to lubricate small hole before applying CA glue if necessary.





Sep 28, 2015, 03:42 PM
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Installing a Hitec MS-82MG servo for aerotow release

- Best location for the servo is flat on its side, you have to carve a little foam out to get it to fit in.

- Drop in some 1/4" plywood or hardwood pieces to fit on either side of the servo with a screwed on top piece. I used a 1/32" plywood to shim the servo up to make it snug.



Sep 28, 2015, 03:57 PM
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Sanding, primer and paint

- I could have spent more time making the CA glue and cloth surface smoother...

- Lightly sand CA smooth and then spray primer. Sand and reapply primer coat.

- Final paint was Krylon acrylic white, several coats.



Next up was creating a scale skid

- Cover the stock red skid with white vinyl and then mount on fuselage to check fit.



- Remove and place saran wrap underneath.



- Lay down a piece of cloth with 3M Super 77 spray glue and purposely wrinkle to create a fabric look. Cut and fit to area indicated.



-Soak with CA glue, let dry.



- Remove after CA glue is dry.





- Drill holes to refit original screws.



- Cut strip of aluminum for skid bottom out of old printing plate material. See your local printer for help.





Fit over newly made fabric skid with piece of 1/32" plywood and basswood to take up space in rear. Use CA glue for all.







- Paint with flat base medium grey.



Sep 28, 2015, 06:57 PM
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Fitting the new skid

- Your paint is dry and you can fit the skid to the Ka8b sailplane.











Sep 28, 2015, 07:06 PM
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Applying the graphic stickers











Small scale detail, handle on rear section of fuselage. Used a small section of wire, glued in with CA



- Covered the stabilizer and elevator with white vinyl. I also covered the white landing gear rim with black.





Wings
- I used some carbon fiber strips (.057" x .177" x 40") on the underside (about an 1.5" back from the LE, right in front of the aileron servo,) knifed a slit, then stuffed down into the slit the carbon strip and added CA glue. Ran a strip of fiberglass strapping tape over. LE will get some clear packing tape.

- One of the other issues I fixed on the stock wing was to add a 4~5mm dia x 10" long metal rod that I bent a ~6˚ deg angle to fit inside the smaller front carbon fiber rods that aren't joined. This has helped strengthen it up considerably. I initially joined the wings together with fibreglass tape, but now see that the larger carbon wing tube and my steel rod could stand to be glued in solid with gorilla glue. The design of the wing joining system is really very, very clever, but really to make the wings work well, both should be joined together solid, it is the only way. Storage and transportation might become an issue for some, I have a large wagen so no big deal.



Radio gear installed
- Graupner GR-16, 8 ch Rx
- Graupner Vario
- Hitec HS-82 MG aerotow servo
- 6v 2300mah Rx 5-Cell NimH battery (148g)



All Up Weight AUW, 1,2kg (2 lbs., 10.5 oz). I had to add weight to front area to balance at 65mm from LE on wing.



Last edited by studioRS; Sep 28, 2015 at 07:17 PM.
Sep 28, 2015, 07:28 PM
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Maiden aerotow and soaring report

After a few somewhat long flights on my Radian to test out our epic thermals, I took my Ka-8b out for the maiden on Sept 28, 2014. It was HOT outside and sunny. Fall colors have started to peak, just one week after the 2014 SeptemberSoar event.

Our local resident expert pilot was free to take her up, so I jumped on the camera to shoot photos. On the third tow he got it up and I took over on my Graupner Tx. Popped into a nice little thermal area we were all experiencing today and had a nice pleasant flight. On my final approach I deployed the spoilers about 40-50% and then had one of my nicest landings to date.

Needed a tick more nose weight after the first tow. I started with 30% differential on the ailerons and might adjust some more because we both noticed a slight tendency to tip stall if rotated to quickly and not kept flat, could just be pilot error. We also programmed in 40% expo on the ailerons and elevator. I'll play with these settings later.

We had an AMR 20 with a nitro engine for tow duty, worked like a top. Our normal AMR 50 tow rig was waiting for parts. All good stuff, love the way this soars, looks super scale and a total keeper.

Cheers, Thompson

















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