Build Log DAW Ka6 Build Log

[CuriousMarc]

We're a few months away from the Los Banos scale meet and it's time to build my first scale sailplane. I ordered a DAW Ka6 foamie kit from http://www.skykingrcproducts.com/rcp...t/DAW_Ka6.html

I really liked the way they looked and flew at the last Los Banos meet (see them at the end of the video http://www.rcgroups.com/forums/showt...73#post7347987 ).

Actually I was surprised to discover that they were "foamies" when I looked up close after the flights. I really did not know what a foamie was, but quickly grasped the prime advantage of it. The crazy Ka6 flyers at Los Banos started to try to run into each other just for fun. They actually succeeded. Pretty indestructible. This is a large scale plane you can fly relaxed. And at 3m in size, it also flew large and majestic, very scale. On top of that I learned to fly full size on a related Ka8, so this brings back good memories.

But I had never built a foamie, and I could not find a build log for the Ka6 - apparently everybody knows how to build them but me . From the excellent online build manual I quickly figured out it's mostly white packaging foam cut to shape with tape reinforcement all over it. It's actually quite a miracle it works! I should be able to do that.

This will be a low profile DAW Ka6 build log reporting my first timer experience, hidden in the cozy internet corner of our club posting area. But hopefully I'll get some help along the way from people in the know .

[CuriousMarc]

I received a personal e-mail notification from Ed shortly after ordering online - Thanks Ed! It's always comforting to know there is a human on the other side! The kit arrived within a week from ordering in one very light carton. The whole thing is mostly made out of packaging foam, so it packages fairly well and is hard to break during transport...

See the pictures. Wings are in 4 panels. I already started assembling one inboard wing panel before taking the picture - couldn't wait. Fuselage is kind of squarish, will need to be rounded up. The kit parts are very simple but complete, with wheel and linkages and all. Each bag of parts has a neat little list of what's inside.

It now even comes with a clear canopy (the foam one is still also included). I remember the Los Banos guys telling me they made a canopy molding plug for their models and made it available to Sky King. That's very kind of them.

[sailhigh]

Marc,
Dave Candee and I bought one each a few years ago. Mine is still in the box, but Dave is in the process of building his currently. You may want to get his input on some things before you proceed which may save you time.

Best of luck with your build

BTW, we missed you at Mission on Sunday, here are a few pictures:
http://www.rcgroups.com/forums/showthread.php?t=815462

[Kai@UCSB]

Marc,

Looking forward to see the building log.

-Kai

[CuriousMarc]

Originally Posted by sailhigh

Marc,
Dave is in the process of building his currently. You may want to get his input on some things before you proceed which may save you time.

Yes indeed, it appears we are building the same thing at the same time! I talked to him briefly at one of our last meetings. Dave, please chime in or post photos of your build if you want.

Originally Posted by sailhigh

BTW, we missed you at Mission on Sunday

That's too bad I was nursing my flu. I took my revenge today by flying both at Dartmouth off the winch with Bob and all (there must have been 5 or 6 of us) in the morning, then trying the thermals off the slope at Mission in the afternoon where I saw you sans glider... Conditions at Mission were mediocre as you predicted, just got one 15 min flight then the haze set in and I packed up... Are you still planning to go back tomorrow?

[CuriousMarc]

I started the inboard wing construction. The wing comes with a channel for the spar pre-cut, but that's about it. You have to glue in the spar, sub trailing edge and trailing edge, rib root and trim/sand them to size. In the process you'll need to cut the foam to install the wing joiner and wing attachement plate, and cut the channel for the outboard wing spar link.

Interesting for me was the choice of glue for foam to wood joints [Edit: see later in the build log, Gorilla Glue turned out to be the best glue to use by far]. I tried the recommended hot glue, as well as Goop (Zap a Dap a Goo II to be exact). I found none of them ideal. The hot glue is nice because it is quite runny and sets very fast, but often too fast. You've about 15 seconds to work with which is very difficult on large pieces such as the wing. Goop gives you more work time, but is, well, goopy and takes forever to cure. Hard to smear in slots and takes a long time to dry, sticks everywhere. I haven't yet tried Gorilla Glue (Polyurethane), which is runny and not too fast. It's recommended by SkyKing . But it foams to 3-4 times its initial volume, so you have to clamp your pieces together so they are not pushed apart and remove the excess glue that oozes out after it's cured. And you have to moisten the wood beforehand to catalyse the cure. Choose your own evil. I found myself alternating between glue choices depending on the task.

I mostly followed the well written and precise instructions (http://www.skykingrcproducts.com/support/Ka6E.pdf ). The only thing I changed was cutting the foam pockets (for the joiner, the outboard spar and the wing bolt plate) before other pieces were glued in. This way there is good side access to cut the bottom. It's much easier and cleaner than plucking foam out from the top. Did one panel with hot glue and the other with goop, and liked neither method...

The only difficulty I encountered was fitting the wing bolt plate over the joiner tube. Because of the wing dihedral and the straight joiner, the joiner tube comes up from the bottom of the wing at the wing root, and you can only set it up so low so it doesn't poke through the underside of the wing at the other end. There wasn't much thickness left to fit the plate over it and have it match the wing profile. I had to thin it a bit over the tube.

[BUFF-USAF]

Hi Marc

I finished my wings, and so far I have used either Wood Glue (i.e. Titebond) or epoxy. Titebond takes 24 hours to really set up and you need to make sure your working area is at the specified temperature. I used epoxy on the spars in the wing.

I am working on the fuse and have set in most of the servos. Find yourself a set of kitchen knifes to make the cuts. One out of the set will become your favoriate. Test them all on a piece of scrap first as some will tear rather than cut clean.

When you make the chanel down the side of the fuse, use a dremel with a depth guage and clamp a straight edge as a guide. Build up you tail feathers first so you can have a direct line to the servo horn.

You should have come to the club meeting, as I brought in my Ka6 for show and tell.

Have fun building!

Dave

[CuriousMarc]

Dave,

Thanks for the tips.

Yours is a better choice of glues. I just tried the Polyurethane Gorilla Glue on an outer panel spar for a change. Started good, very easy to apply. Put weights on the spar to prevent it from moving when the glue foams. Of course the glue comes up the sides and tries to glue the weights to the spar . Then to my surprise it foamed through the porous foam on the underside of the wing and tried to glue the wing to the bench ! Fortunately I caught both before it was too late, but this is yet another imperfect glue. Epoxy was the right choice. I also have Titebond wood glue, haven't tried it yet, I'm not sure if I have your 24 hours patience...

Wednesday evenings is the day I have to drive my daughter to her harp lesson, so I can't make it to the club meetings unfortunately. So the web is my alternate meeting place...

Any pictures of your build you can share with us?

[MAVA]

Good Job Marc,

You have come a long way from the day you flew my white THL Zagi. I also have one of these Models. Marc. You are inspiration!! Looks like you may pass me by. I will try to finish mine by April 5. It has been an insider tradition to go to Los Banos a few weeks before the Scale event to “Bash it (just have no pressure flying day-work out the kinks in the models) out with other fliers”.
Talk to Eric to get the particulars on the day.

Keep up the good work,

PS.. build the model with Gorilla glue it will be a lot stronger. If you do use Gorilla glue, use a hair spray bottle with tap water, and spray both contacting surfaces. Then apply glue. The glue joint will be stronger, and the glue cures a little quicker.

Martin Vargas

[CuriousMarc]

Hi Martin, nice to hear from you! "Flying" is a flattering word. I thought I "crashed" or more exactly "bounced" it within a few seconds ... Yes, all this thanks to your and Eric's introduction to RC flying on that day. So now I will have one of each, a "woodie", a "crunchie" and a "foamie"... By the way, you are the one that pointed these Ka6 out last year and suggested I started with that for scale. See, I do listen. Looks like we will be able to fly formation at Los Banos with you and Dave...
Marc

PS: totally out of subject but I can't help - did anyone see the moon eclipse tonight? I managed to take a picture during a break in the clouds.

[MAVA]

Marc,

You are on the path to success, I see you have picked-up some of the slope slang language, now you really being intoxicated with this addicting hobby….

About last night, the moon was spectacular. I was at about 650 Meters of altitude watching the whole thing through 14” Schnidt-Cassegrain Celestron Telescope, but was most spectacular was watching Saturn to the lower-left side. I do wish we had optical filters to see the rings in full color.

Let’s see who finishes the model first, I will post some pictures of my progress, but I do “wish” to implement a full flying elevator like the full scale-the model will fly much better with the modification.

Martin

[sailhigh]

Marc, Dave, Martin,
Here are a few links on KA6 modifications builder are incorporating.

http://www.skykingrcproducts.com/rcp...a6_porter.html

http://www.skykingrcproducts.com/rcp...W_Ka6_rob.html

http://www.skykingrcproducts.com/rcp..._Ka6_greg.html

sean

[MAVA]

Here is something interesting...

http://www.rcgroups.com/forums/showt...hlight=EPP+ka6

Martin

[MAVA]

Some pictures to help with sanding the fuse to shape.

http://gamma.nic.fi/%7Emtkoskin/nokka_1.jpg

http://gamma.nic.fi/%7Emtkoskin/nokka-siivet_1.jpg

http://gamma.nic.fi/%7Emtkoskin/oh478_runko_1.jpg


http://gamma.nic.fi/%7Emtkoskin/oh478_runko_3.jpg



http://gamma.nic.fi/%7Emtkoskin/sivup_runko_siiv_1.jpg


http://gamma.nic.fi/%7Emtkoskin/sivuper_runk_2_hyva.jpg

[CuriousMarc]

I tried Gorilla Glue for the spar on this one. Humect the wood, brush it in, put weights on the spar. The glue foams but it is very easily sanded off, unlike goop or hot glue. Some glue seeped through the bottom of the wing, nothing bad. A better glue choice altogether.

The aileron shaping takes a patience. A sliver of the trailing edge has to be cut to match the scale wing plan (I did it the wrong way first!). Then the aileron has to be sanded to conform to the wing profile and equalize the trailing edge thickness. There is washout in the tip which requires care in sanding the aileron.

The tip of the wing has to be cut to scale shape and rounded off. This is easy and it looks nice!

Pictures tell most of the details.

[CuriousMarc]

Originally Posted by MAVA

Here is something interesting...

http://www.rcgroups.com/forums/showt...hlight=EPP+ka6

Martin

Yes, saw that, spent a lot of time trying to understand from the posts what's the best finishing method.

On that post, thinned goop, spackle, spackle + elmers, spackle + wood glue, water based wood varnish (Minwax Polycrylic) + talc are discussed.

Here is a long discussion on the merits of different combinations, where nobody seems to agree:
http://www.rcgroups.com/forums/showt...t=814533&pp=50

There are a few other methods here:
http://www.rcgroups.com/forums/showt...t=778272&pp=50
It's actually one of the very few posts where someone actually tried different methods and compared them. It is the only one to mention "sparnish", spackle + acrylic wood varnish.

In the end, I couldn't tell from the posts. So I decided to try it for myself (except thinned goop). Didn't explore PU/RT either (polyurethane - roofers tape), I intend to use regular reinforced strapping tape.

So I gathered lightweight spackle ("Shur-stick"), Elmer's glue, aliphatic resin (Titebond) wood glue, water-based wood varnish (Minwax Polycrylic), and Lightweight Marine Filler instead of talc (West Systems 410 Microlight Fairing Filler, from a boating outfit), and started experimenting.

First I started with nothing as recommended by some (and the DAW manual): tape over foam. You get what you expect: the grain of the foam is showing through. That's fine for some people, and the lightest weight finish, but not the appearance I prefer.

Then I tried all the spackle variations: spackle by itself, spackle with elmers, spackle with aliphatic, spackle with acrylic. Tried some of each next to each other on a piece of foam (see pictures), let it dry and sand lightly.

Worse is spackle alone. Stays very porous and uneven when it dries, sands difficultly and crumbles away.

Slightly better is spackle + Elmers. Slightly stringy, but dries harder than spackle and sticks better, less crumbling.

Even better is spackle + Titebond (aliphatic resin). Harder and much easier to sand, but tends to be stringy and leave voids so you need several layers.

By far the best was spackle + Minwax Polycrylic. A dream cream, would go on and stay almost perfectly flat before sanding, with the consistency (and looks) of whipped cream. And the solvent is water. Thick layers take a long time to dry though (one or two days), not good for filling large voids.

You can tell by the pictures, I wrote on it and the residual surface roughness shows very well. The Titebond and Acrylic patches got two layers with two light sandings. The acrylic mix is perfect, and needed little sanding. I would use the Titebond mix as the first layer only if I had a big hole to fill in, it has more volume to it.

I also tried the Acrylic + Lightweight Filler, ended up with something slightly worse than the Acrylic + Spackle, on the thinner side.

So water based acrylic varnish + Spackle (Spackrylic) is my current best guess before I tape [Edit: see later on post 43, the recipe is 5 parts of lightweight spackle (Shur-Stik brand) to 1 part of Minwax Polycrilic semi-gloss]. I'll use the Titebond mix to fill up the troff over the joining tubes.

[MAVA]

Good Day Marc,

I see you are making monumental progress on the model.

My model was bought used – Partially built, the spars were glued, and the wings fully assembled. The model I have is the original Dave’s Ka-6-not everything on this model did not fitted so well.

I saw two of these KA-6 foamie models with flaps on them, and I know the original KA-6 did not have flaps. On those days when the lift is very weak, and the ability to add a few degrees of camber means the difference between flying and sitting on flight-line of the cliff. I know you can change flight modes with your JR 9303-Fight modes will pay dividends on multi channel model as I do this with my scale stuff, but I have the JR(The original German version of the 9303) MC24-same menu as the 9303. Try it..?

I’m hoping to finish mine in two weeks. I want to make it out to PCC’s Glider Day-Power Club in Half-Moon-Bay. I think the date is March 9th. Eric belongs to the club-ask for details. For me it is a three-hour drive, but very much worth it. If Brian Chan shows-up with his Electric Telemaster, he could do some Aero-Towing for us..

That is what is cooking here..

I will post some pictures of what my model(stages)looks like…


Martin

PS what is the recipe ratio to Spackle to Minwax and Titebond to Spackle ?

Ohh.. One last question, what brand of Strapping tape are you using?

[CuriousMarc]

You're well ahead of me. I'm not even sure I can finish mine in time for Los Banos - I need more rainy week-ends.

Mine doesn't have flaps either by default. But you bet I will add them - can't live without them since I got used to them on my "crunchie", and probably couldn't land at Mission without them either. And I do use the flight modes, all 5 of them...

Not much Minwax for a lot of Spackle. I prepared a small batch and used a few dribbles coming down a small wooden stirrer in about 2 or 3 tablespoons of Spackle. Haven't quantified it yet. [Edit again: see later on post #43, the recipe is 5 parts of lightweight spackle (Shur-Stik brand) to 1 part of Minwax Polycrilic semi-gloss]. You can tune it to whatever consistency you prefer. Same for the Titebond: little glue for a lot of spackle

I had trouble finding the reinforced strapping tape. I finally found some 2" wide "Scotch Strapping Tape" from 3M at Target, hidden in the stationery isles. It has longitudinal filaments. I found 1" and 1-1/2" wide reels of the same tape at OSH.

Let me know if you go to Half-Moon Bay, I might be able to go too.

[CuriousMarc]

By the way, there is a very detailed build log of another SkyKing plane involving very similar building steps, the 48" Whirlwind by Brian Courtice at:

http://www.rcgroups.com/forums/showthread.php?t=784267

[BUFF-USAF]

Hi Marc

You asked for some pictures, so take a look at these. One thing that I did to make mounting the servos for the Rudder and Elevator was to do the following:

Cut a rectangle hole all the way through the fuse.
Then set in one of the servos to see what the depth would be. After subtracting 2 x of this dimension from the width of the fuse, I made a wooden frame to mount the servos on then I could position them without being concerned about cutting the hole the same depth on each side.

Enjoy

[MAVA]

Buff,

love the pictures, Thank You...

Marc,

The picture of the filament tape you have is the looks like 100lb type...

Here is tape vendor-we get boxes, and other packaging supplies, but I can not just buying a case of this high-performance filament tape. I like 3M893. This 893 tape really nice tape, but the roll is about 14 bucks.

http://www.uline.com/Group_241.asp

Here is a better alternative, but I think it is available only through the online side of staples.

http://www.staples.com/webapp/wcs/st...&cmArea=SEARCH

A friend of mine went to Office Max store got some of that really fancy cross grained filament tape-look in your area for an Office Max.

I think the instructions said only fifty yards are needed.

I'm going to buy the tape available through Online Staples.

Martin

[sailhigh]

Looking good Dave I didn't know you were this much ahead.

sean

[CuriousMarc]

Dave,
Thanks for sharing the pictures. Nice work! You're well ahead of me, I better booggie to catch up...

Martin,
Now I understand your former question. I didn't even know there were that many tape choices! I can't find a product number on mine, nor a strength rating. Must be the cheap stuff, you're probably right. I'll look at Office Max, there is one nearby.

- Marc

[CuriousMarc]

Trying to catch up with Dave and Martin...

Wing assembly was straightforward. I'm getting better at glues.

I put two servos in the wing. The doc says you can put a standard size servo in there but I wouldn't dare - there would be hardly any foam remaining. I used a Hitech HS-225MG for the flaps and a flatter HS-125MG for the ailerons.

I wondered how I was going to manage a controlled depth cut for the servo cavities and make a nice flat bottom. A board cutting tool from Michael's (a trick I picked up from a post) and a slightly modified Dremel tool did the trick really well.

I added my own little extra by using a DB-9 connector at the root, I'd like to have an auto connection to the fuse - we'll see if I can manage that.

[sailhigh]

Nicely equipped work bench Marc. Now we know why your planes come out so beautiful.

Sean

[MAVA]

Marc,

You are way to neat.. I always got three or so models going at one time... I can not just work on one model at a time...

Looks like you can finish it off before Los Banos..


Martin

[MAVA]

Guys,

What is recommended for control actuation of is very common approach, but this conventional (picture 1) approach has flaws?

Loss of control resolution from radio

Problem with radios that cannot reduce trim percentages

Loss of output torque from servos

Eye-sore..

Susceptible of snagging weeds on landing, or ripping servo gears.

Picture 2, I saw this on a six meter gilder five years ago, very effective, clean, and all control resolution is maintained.

What do you think?

Martin

[MAVA]

Marc,

I'm looking at pictures 3614 & 3613, and I see I minor problem. The angle of the servos should be as the control surface-to getting best torque. There is no slack in the servo wires embedded in the wing.

This is my two-cents; I like to provide additional electrical shielding by winding my own servo extensions in a twisted (see my picture 39) pattern-like 10/100-computer cable. Helps with controlling or eliminating that common servo buzz.

I know we are not building satellites... This what happens when you been in the hobby for thirty-years, every little detail matters...

Martin

[MAVA]

Marc,

Oops.. I mean parallel to the control surface.

Martin

[CuriousMarc]

Martin,
You're absolutely right, the servo should have been mounted at an angle for a mechanically sound linkage. I just overlooked it . The angle mismatch is not too large, the relatively long wire linkage should be able to take the slop - I will see if I try to move the servo around or just let it be...

I also heard about the crossed linkages, particularly on flaps to reduce drag under the wing and increase the total angular movement. Here are some examples of what people do on the Onyx flaps:
http://www.rcgroups.com/forums/showp...4&postcount=16
http://www.rcgroups.com/forums/showp...8&postcount=51
That was too advanced for me, I did it the regular simple way.

[slip stream fox]

Wing Servos:

I think you should have to worry about it because the aircraft is a high wing. So the wing servos shouldn't matter.


Tim

[TRISME]

Looking good guys, sand it round and bring it to Banos. Hopefully all four of us will have ours there again. We don't necessarily try to hit each other, it's just fun to stack them together in the pumps. We were definitely having a good time, you probably couldn't tell from the video. See you there,
Tom Ramirez

[TRISME]

Brian had some more Ka-6 footage among other things. www.youtube.com/user/jeffersontucker

[CuriousMarc]

Thanks Tom! This is a spectacular video of the no less spectacular flying I remember, complete with the mid-air ! To me this was a high point of the Los Banos meeting. And the reason I am building one today. OK I misspoke. Let's say you weren't trying to purposedly avoid each other ? Here is the video in embedded form:

Ka6s at Los Banos (4 min 44 sec)

(4 min 44 sec)

[CuriousMarc]

Here are some pictures of the two types of tape I could find. The longitudinal filament I found at Osh and Target, the crossed filament I found at Fry's. Any recommendations?

[CuriousMarc]

I started fuselage work with the wing attach. I wanted to see if a DB-9 auto-connect modification was possible before going too far. It actually was easier than expected. I'm starting to like the expanding properties of the Gorilla glue! Pictures tell the story.

[CuriousMarc]

The canopy was a head scratcher. There are no instructions on how to mount the clear plastic canopy . Ed from SkyKing RC mentioned that most people just tape it in place.

I made a cockpit floor and backing to fit the fuselage and canopy, from some plywood I had around. The curvy floor was the tricky part. I have not finalized the attachment method beyond my wooden rail and grove method.

There must be better ways, but at least this one worked, it fits well and looks fine.

[CuriousMarc]

Just an aside on pilots, because I found it surprisingly difficult to get nice ones. There are some extraordinary ones at Axel's pilots, but too nice and too large (1/4 scale) for this plane:
http://www.sailplanes.com/saxel.htm
http://www.axels-scale-pilots.de/

I ordred some from William Brothers, very inexpensive, the 1/6th scale will fit:
http://www.williamsbrothersmodelproducts.com/rc.html
http://www.hobbyfever.com/index.php?...62d1ecb76e5e1a
Great deal for the price, they look a bit stiff, they were among the best I could see on the web.

Also tried the cake ornament dolls - just the right size after a bit of chain sawing.

Just for kicks, I also bought some lightweight polymer clay (at Michael's) and tried to make one myself. It was much easier than I thought, or I might have had the luck of the beginner. Takes only 15 min to cure in the oven, is quite light, and easily sanded and carved for details after it's cured. Sorry I can't find the name of this wonderful clay anymore, the kids used it all up to make pottery! I liked the result, so he got the job in the end.

His name is Peter Brick. Because he flies like one (I'll blame it on him )...

[CuriousMarc]

Nothing extraordinary there. Lots of drawing then deep foam cutting to put the servos in. I built this somewhat out of order because I wanted to do a trial balance before I purchased the batteries. So I finished the tail group first.

Turns out it took 12.1 oz (343g) to balance it, which means I could put five 4/3AF type 4200 mAh NiMH batteries from Tenergy and be almost in balance (312g). Bought them directly from the manufacturer in Santa Clara, very cheap, comes in two days with regular shipping:
http://www.all-battery.com/index.asp...TS&Category=16

The shaping was a lot of fun and done very rapidly. I cut along the recommended lines, then took out the sharp corners progressively with a razor knife, and sanded a little with 60 grit glued on a long piece of wood to finish. Piece of cake.

The only problem I encountered was with the laser rods provided in the kit. They were way too tight and the servos had trouble just pushing the rods. I instead bought 0.060" dia 48" length carbon rods (just $4.50 each, product code R02-A from ACP)
http://www.acp-composites.com/acp-cr.htm
and threaded them in the inner laser rod. Much better, very smooth, no resistance.

It's on to finishing now...

[sailhigh]

Marc,
I find your precise work, even on foamie, very interesting. I'm sure this bird will fly as well as it's built. Keep up the great work. Can't wait to see her in the air.

Sean

[TRISME]

Looking good Marc, the girl gets my vote. I need to pester Gary and Ryan to fix their KA6's for Banos. See you all soon.
Tom

[CuriousMarc]

Originally Posted by sailhigh

Marc,
I find your precise work, even on foamie, very interesting. I'm sure this bird will fly as well as it's built. Keep up the great work. Can't wait to see her in the air.

Sean

It's just my style, it's an overkill for a foamie for sure... I sincerly doubt that it'll do anything to its flying, except maybe a good wing surface finish helps (it does on full scale!). All my add-ons and spackling will make it a bit heavy also. You could stuff the servos in, tape it and be done in a week and it would fly just as well... But I'm having more fun this way .

[CuriousMarc]

Pretty straightforward finishing process. I used one layer of spackle + Minwax. Proportions were 5 parts of lightweight spackle (Shur-Stik brand) to 1 part of Minwax Polycrilic semi-gloss, used very little of it. Followed by a sanding with 220 grit paper. Two layers could have done better but I wanted to keep the weight down and I thought the finish with the first layer was good enough. Taping is quick and easy, it is preceded by a 3M77 spray and 15 min. dry time. Covering is as usual, except I also sprayed a light coat of 3M77 beforehand.

One half wing done, one more to go, then the fuselage, then fly...

[CuriousMarc]

The fuselage got the same 5:1 Spackle:Minwax treatment + sanding as the wings to start with.

Then I experimented with a finishing 1:4 layer (1 part Spackle, 4 parts Minwax). This makes a "paintable" mixture which you can just brush on, and dries pretty flat and hard. You can sand this layer to an extremely smooth finish with an electric sander (but it's too much work by hand, unlike the 5:1 mixture which sands very easily by hand). However it did add some weight (see below) - I would not recommend doing that second layer, particularly at the back, and the front is going to be all taped up anyhow.

A second trial balance revealed it had gone a bit tail heavy from the second minwax/spackle layer. I therefore made weight saving holes in the tail group. Only saves a little less than an ounce, but that's 10 oz. away from the front, so it was back within reasonnable balance. By the way I tried several unsuccessful techniques to make nice round lightening holes, until I unearthed a forgotten attachement from the Dremel box, and then it was done and over in 10 minutes.

Taping was straightforward except for the front. First I didn't like the recommended nose taping scheme which goes sideways with overlapping bands. It was sure to result in many ugly tape joints going the wrong way and the "golf ball wrapped in paper" look later on. Also, the tape takes very little compound curve before it starts to make ugly wrinkles. So I taped it along the other direction (along the air flow), and I separated the tape in fingers as soon as I saw it wrinkling, letting each finger go it's own natural direction without wrinkles. It worked really well (see pictures).

Covering was uneventful. Spray the fueslage with 3M77, let dry 15 minutes at least, lightly iron the covering film down with low heat so it sticks at the edges, give it a good hot hair dryier shrink until it's all under tension and wrinkle free, then go over with the iron at high temperature while pressing down to make sure it sticks. I used the same fingering techique up front, although the cover will wrinkle a lot less and just a few fingers will do.

[CuriousMarc]

Nothing special here. Just some views on the linkages and the final assembled picture. I got it ready just on the morning of the Los Banos meeting, the day after I came back from an overseas trip. Fortunately I woke up really early from being jet lagged. Turned out perfect, I needed the extra morning time...

The ship comes out at 94 oz (2.7 kg), not too bad at all.

[CuriousMarc]

That was a very special day. This is the meeting where I made new friends and picked up the hobby two years ago. It's the first time I could fly in the main session, because I didn't have a scale plane before.

The Ka6 was in good company. Dave did bring his newly built one also for a maiden (the one he provided some pictures of above). The SoCal flyers made good on their promise to bring their four Ka6. Sean introduced me to Tom (the SoCal flyer who encouraged me above) and a few others saying: "this is Curious Marc!". Now that's Internet fame .

It was quite windy, measured at 20 to 25 MPH before I flew. There was lots and lots of lift. Dave went up first, and his Ka6 caught the mighty lift and went almost straight up from the toss, then he penetrated easily and it flew well right away. His son Tim landed it a bit later in the strong wind for a very successful maiden.

My first flight didn't go as well, in fact it was hair raising. First of all I am not accustomed to fly in such windy conditions, my only slope experience being in the soft winds and mild thermals of Mission Peak. Eric launched for me and immediately the plane plunged down instead of going up. I pulled on the stick and it went way up all of a sudden. I was bobbing up and down for a while with scary plunges as soon as I released the stick, being able to bring it in precarious and seemingly unstable balance only with the stick pulled way back. I couldn't trim it to fly level, actually the trim command didn't respond at all. Fearing something wrong, I attempted an emergency landing aiming for the high and soft weeds way back. Fortunately I was able to land well despite the very twitchy picth response and the wind.

Now I could breathe and try to make sense of what had just happened. The culprit was a combination of a slightly down center elevator position and the leftover programming that had been copied over from my Onyx program. The Onyx is now well sorted out, so I had reduced the trim step to a very small amount. That's why I couldn't seem to trim the Ka6. As for the ultra twitchy response, it's a combo of too much elevator travel and the exponential that was dialed in (also a leftover). I was flying with the stick way out of center in the region where the exponential goes the wrong way, magnifying everything you do instead of calming things down.

So I re-center the elevator (actually a little up just to be sure!), reset the trim step, turn off the exponential (it was controlled by a switch), and move the elevator linkage up one notch on the horn to lessen the travel. Good to go again.

Second time is the charm. Goes right up from the toss, a little forward stick brings it to level flight, and then I am able to trim it after the first turn. It's very responsive in roll, needs no aileron or rudder trim whatsoever - goes perfectly straight. The 50% aileron differential and 50% aileron to rudder mix is a very good guess, it does nice coordinated turns. I fly conservatively big S'es for a while, then throw in the exponential. Now it's perfect and very easy to control.

Mild mannered, doesn't go very fast as you'd expect from the thick wings, but flies much better and steadier than I would have expected a foamie to fly in the strong wind, and has very effective control authority (more responsive than my Onyx). I try a little bit of flaps but I have too much dialed in at the smallest setting, it just induces drag and makes the plane go down - I'll have to try smaller amounts later. No flaps needed anyhow in this lift and wind, unless you like to fly backwards. I enjoy this and am getting progressively less tame, but soon the wind strengthens until it reaches uncomfortable levels (for me at least). I am getting tossed around more than I like, the plane is just not ballasted enough for that. The wind was measured at 32 to 39 MPH just after I landed.

Time for a windy landing. Sure enough I forget the cardinal rule of landing in the wind (in full scale we add 1/2 the speed of the wind to the regular landing speed). 1/2 the speed of 39 MPH is a lot of speed for a model airplane. Instead I come in nice and slow, very slow, much too slow. Almost standing, I get picked up by some lift to about 2 feet high, then blown sideways like a loose leaf. Oh no! I am blown over the wrong side of the flight line where people watch it bounce on the nose from really close up. I barely see it cartwheeling and going upside down before it disappears behind the tent right where all these nice scale planes are lined up . Oops.

Time to run back there and survey the damage. But people have just turned her around and lined her up next to the other planes right where it fell. Call it a new form of parallel parking ... She is plenty fine, except for a few wrinkles on the nose covering where it flexed, and the tail fin which feels loose. It partially broke inside the covering when going upside down, right where one of the big holes makes it fragile (it's already fixed). So in fact this was a test, I can now report from experience that foam does indeed bounce, not break .

Wind is way too strong for me (and most of us) to fly again, but the undaunted SoCal guys now do their stunts and formation flying in their four Ka6 as if it were a stroll in the park. They use a steel joiner instead of the aluminium one to ballast the the plane, and it looks perfectly fine in 40 MPH wind (with them at the commands at least). Unlike me, they all land with ease. I have to train Peter the pilot better.

Now the best part of the story. Award ceremony in the blowing dust. And the best of show winner is... the red Ka6! I can hardly believe it. Apparently they didn't judge by the landing prowess! I felt sincerely touched by this, and realize that there were many better built and nicer looking vintage and glass ships - which also got their awards. But for a simple foamie, this one turned out fantastic.

Thanks to all of you who helped me. I hope to post photos and videos from the meeting when they are available, Gepetto and some others were hard at work documenting it. In the meantime, here are a few of them, the first time I could step back far enough to have the plane fit in the pictures.

Marc

[CuriousMarc]

Here are a few more pictures of the Ka6's in flight at Los Banos. Pictures from Gepetto, Sean and Donn Schifano. Some of these pictures are re-posts from the Los Banos thread here:

http://www.rcgroups.com/forums/showthread.php?t=840141

In chronological order, here is Dave's Ka6 maiden flight...

[CuriousMarc]

Here are some of my two flights.
.

[CuriousMarc]

The group of SoCal flyers, who were the inspiration for this build, brough their four Ka6 as promised. Undaunted by the now very high winds, they finish the day with spectacular aerobatic and formation flying.

[wizzzer]

Congratulations, Curious. You earned it. Your meticulousness serves you well. A great job on the build log and flying under conditions you were unfamiliar with. I will be at Dartmouth on Sunday with a winch and retriever. Hope to see you there.
Bob