Back to the Yak - Yak-9 Build, Part II

I have a bad habit if I go up without a plan, or go off freelancing, having added an extra half ounce of fuel to play with after the pattern; I've been known to momentarily daydream... Stunt Coma?   Talk about the attention span of a, 8 year old. It's been known to cause some close calls, but I've been pretty lucky so far. After I re-plumbed the tank recently, it cut off the instant I leveled off after my OH8, the last maneuver. That was close. Now it takes 1/4oz more than it did before.

My Skyray won't lean out until a few laps after I finish the pattern. If I go up to execute just the beginner pattern, I know the gas will run out about 8 laps after the last maneuver. But I only fly one plane, so it's easy to keep track of. If I had a few of them, I might have the same problem you do with untimely surprises.
Rusty

BTW, I'm taking the night off. I made a painting jig for it this afternoon... neato... and mounted the bolt plate on it sideways. Yiiiii! It's a Rusty thing. It's also a sign that I need a break. If I'm up to it after tomorrows quarter round project, our regularly scheduled work will resume. Sunday depends on flying or not. After all, that's why I toil in the shop. 

Just mount the whole thing to a pivot so you can get at all sides...

Phil

I just hang it by the tailwheel from a string. Engineers.....   

pkrankow wrote:Just mount the whole thing to a pivot so you can get at all sides...

Phil

It's a 3/4" PVC tube clamped in a vice. A dowel runs through it with a plate on the end that bolts to the engine mount. There's a jam wedge fixed to the dowel behind the PVC tube so I can lock it in any position 360 degrees around. No pivot though. I'm going to use that when I finish the filets and paint it. Also when I make the rear control linkage.

Cribbs74 wrote:I just hang it by the tailwheel from a string. Engineers.....   

I've always done that. I just want to pretend like I'm an expert sophisticated builder of fine models. If my friends could see me now. Lol

Also, let me straighten this engineer thing out. I have an Associate degree in Electronics Engineering Technology from Devry University, Atlanta. So I'm not really an engineer, just a knowitall. In an industrial setting, I would be an engineer's assistant, the hands-on guy that implements the fancy concepts, and figures out why the smoke got out before he/she asked me for help. I actually worked in the office machines industry, Canon equipment to be specific, and later Oce'. First as a field tech, then a master technician/troubleshooter and trainer. I carried a tool box. And later I classroom and lab trained factory techs and also the Japanese techs that came to America to be troubleshooters for stumped dealer techs.

Just setting the record straight. Engineers know a lot more Physics, chemistry and calculus that I learned. My occupational specialties were electromechanical nightmares. I loved it like being paid to play. I got to see the inside of so many types of businesses and industry that I would have never known about otherwise. I even had to work on a machine at Cape Canaveral one time. Stood under the wing of a Space Shuttle, and got to go on a Sperry corp Navy spy ship... they said it wasn't.
Just keeping the smoke in-Rusty


EDIT: I can tell you this much, now that I've used Microballoons twice now, having finished the stab and doubler/cheek edges last night: at least for the 30 minute epoxy I am using, the working time is cut nearly in half before it's unusable. I was able to dump a little alcohol into the cup and rescue the last details. It looks pretty good this morning.

It's gray!


The primer made every imperfection visible. I hope it'll sand out clean, but no matter, I'm spraying the color tomorrow. Great painting weather today, 78 degrees., tomorrow 67. While the white cures, the Reed Speed and Skyray both are getting started.

Now that I've used Microballoons twice, having finished the stab and doubler/cheek edges last night, I've learned that for my 30 minute epoxy, the balloons cut the working time nearly in half before it's unusable. Last night I was able to dump a little alcohol into the cup and rescue the last details. I didn't have the time to make the cheek and doublers quite as pretty as I had hoped, but it still looks pretty good.
Rusty

I'm diggin it!

If you do NOT need the weight and strength of the epoxy an alternate method I use frequently is the DAP Fast N Final light weight spackling.

Two table spoons into a large mixing cup and a little water to keep it workable for a few minuets (additional water as needed)

Tape out the wing and fuselage then goober the stuff on and shape the fillet with a 6" round nose propeller.

Let set a few seconds then remove the tape and with wet finger blend in the raised lip from the tape removal. Let set a few more minuets and with nose up flood thin CA down top bottom of wing fillet. The spackle soaks up the CA fast and I never need to use insta set spray. This stuff is fine enough grained that I rarely need any sanding other than to blend at trailing edge. Dope, Paint, film, or what ever you finish with sticks to it well

Nothing wrong with epoxy and filler be it talc, microballons, cornstarch, as it usually is a good fuel proof strong joint and nice finishing touch

I find the spackle faster with less mess for the same effect

Hi Fred, Dap is exactly what I've always used in the past. It's as hard as a rock after you hit it with CA. The low-wing Yak has little bottom wing support, especially after I shape the air scoop to be realistic,  and I thought that was a great excuse to try microballoons and epoxy, so now I have a lifetime supply. I didn't know I was getting so much from Sig. It's a pain to mix, but makes pretty fillets. I had a couple of gaps where the rudder mates with the fin, so I tried mixing some balloons with regular old Testors airplane glue in the green and white tube. It got sort of bubbly, but it seems to be a good bond. I pre-glued the two parts with plain Testors before applying the mixed glook. Haha, I made a new word. We'll see how good that idea was the first time I do an inverted landing.
Rusty

It looks like it's going through that awkward phase of life where everyone is better looking.  




Too cold and rainy to paint or fly, so I'm spending a seriously anal amount of time detailing every last little thing. Sanding and spackling, filling and blending, and hoping the forecast for nice weather comes true this weekend. By Sunday it should be painted and curing in the house while I move on to my other projects.

Only 25 days to get my Reed Speedster submitted. At least I have an engine for it. I doubt if it'll keep up with anything JP throws at it, but I hope to make up for that with a brilliant fast design. I think I have all of the materials ready to build it.
Rusty

hey Rusty, I'm ready to start building my racer, but I'm waiting for you to start, lol!

I copied some plans today to used as a rough guides for the planes proportions...but left them at work : ^(...

Yaks looking good, what color you gonna use?

It's going to be white with red stars and markings. Red Cyrillic text on the nose under the exhaust pipes. I'm going to make the exhaust block this weekend with aluminum tube. I might do panel lines and rivets too, but I'm thinking about blowing that off and moving on. It'll be in the house for a couple of weeks curing, so I might do it. My text on the nose will be different from the picture, and unfortunately I can't find any red stars with the outline around them, so I'll just do solid ones. I have a two blade white spinner already, but I want to get a three blade one.

This is the idea:

Rusty,
Have you seen these? Not the exact outline around the star but better than no outline.

http://www.majordecals.com/pdf/PAGE-08.pdf

Jim

JPvelo wrote:Rusty,
Have you seen these? Not the exact outline around the star but better than no outline.

http://www.majordecals.com/pdf/PAGE-08.pdf

Jim

Close enough, I bookmarked them. Thanks a bunch.
Rusty

My makeshift paint booth



First coat of flat white. Waiting for second and last coat of gloss white in just a few minutes. I'm skipping the Lustrekote, except maybe on the outboard nose. After that I'll add the flap coupler, bottom wing retainer, and its Russian knockoff of the P-51 air scoop.

Cool man, you did a great job on the sanding. Should be a lightweight.

Cribbs74 wrote:Cool man, you did a great job on the sanding. Should be a lightweight.

I sure hope so. I got a little carried away with the glossy white, but not so much that any runs appeared as far as I can see. It's drying now.

I started cutting the aluminum exhaust pipes. There is a masked area on the cheek where their block will be glued. It's been a good day in the shop so far. 70 degrees and blue sky today. Maybe I'll go fly the Streak in the church yard later on.

Can't wait to see the pipes. It's hard to picture them.

I JB Welded the elevator control rod today. The reason I'm posting this is because it was yet another learning experience. The first time I made a linkage like this, the short one from the bellcrank to the flap horn, I couldn't understand why it didn't fit right and had to do it again. When you plug both ends of a CF tube, the JB Weld or plain epoxy heats as it polymerizes. We all know that. But DUH!, it didn't occur to me that it would cause air expansion inside the tube and try to push the plugs back out.

So when I made the long control rod, after gluing, I blocked both ends between weights to keep it from pooting out the pieces. This one will be correctly adjusted when it cures. Just thought I should share that since I know a few of you guys are starting to use CF.

Also I had no fancy barbed Tom Morris type end plugs, so I used three pieces of brass which should capture enough glue between them to retain the 1/16" wire end. Sanded, cleaned with acetone and soldered. The other end is threaded rod and was slightly too tight to go in without splitting the tube, so I collared the rod end, took my 4-40 tap and threaded the inside. Then JB Welded the threaded rod with the ball link already screwed onto it.




The Yak's coming out party with decals and all that pretty cosmetic stuff will come next.
Rusty

Still no decals and canopy paint, so no pictures yet. But I finally got my adjustable fuel tank brackets made today. Glad I bought extra 4-40 threaded inserts to mount the aluminum brackets. So the fuel system is plumbed, red Loctite on the engine bolts, a new glow plug, an APC 9x6 prop. I put some bigger wheels on it. The only thing keeping it from being airworthy is the balance. It's tail heavy as a pig. It weighs 31.4 ounces now, and I think it might need 5 more oz up front to get it to balance 1.5" behind the LE. I'm not thrilled about that. It balances at 2.5" now. Still looking at Thursday or Sunday for the maiden.
Rusty

I can't believe it's that tail heavy. Any chance of bring able to slide the engine forward? Have you mounted the tank yet?

Cribbs74 wrote:I can't believe it's that tail heavy. Any chance of bring able to slide the engine forward? Have you mounted the tank yet?

I just read at SSW a post Ken made in 2008 saying to start with the balance at the forward leadout. That's about where mine is now, so maybe there's really not a problem. I'm going to run back out to the shop and double check that. I've been going by some posts that said 1.5" behind the LE at the root, but that seems pretty far forward.