Skyray trim??

[Chris Fretz]

Shear webs help, but that's as far as you want to go with a nice rigid wing structure until you're not crashing all the time.

The bad thing about the Skyray wing structure is that the covering holds it rigid, you have to tweak it to get it straight, and it's always warping up again.  The good thing about the Skyray wing structure is that the covering holds it rigid, and when you thump it hard into the ground the covering bursts and the damage to the actual wooden structure is minimal.

True, I "pancaked" it last year, only thing that happened was ripped monokote.

A hump in a wing can't be good. But good for you for sticking to it, that's what it takes in this sport. Howard is right, as several have mentioned, the tab is a last resort. But in a case where you're just beginning to learn the basics of aerobatics, if all your efforts fall short and you finally must do it, it can keep you flying long enough to build your next better straighter plane with all of your newfound knowledge. One that will help you learn to fine tune your shapes without having the plane's shortcomings burned into your developing muscle memory. It seems that's what I am doing right now too. Flying patterns and sometimes winning with an old beater while finishing my build of a proper stunt ship.

I recommend on your next wing to build in shear webs to help hold it rigid and straight. And to reduce flexing under heavy loads. I put webbing in the trailing edge of the Osprey, my Skyray/Streak-bash I posted earlier(still had a tab, but hey, I'm new at it too). Or you can put them between the main spars too. Here is a very good reference website for aerodynamic building techniques.
http://www.airfieldmodels.com/information_source/math_and_science_of_model_aircraft/rc_aircraft_design/shear_webs_in_model_aircraft_wings.htm

I usually need to look up something on that site every time I'm building a new plane. The search button is at the bottom of the left menu column, and they cover every part of building a plane.

Hope that helps,
Rusty

I'll check it out thanks!

Do you guys use wing gigs or something when you're building airplanes?

[RknRusty]

Shear webs help, but that's as far as you want to go with a nice rigid wing structure until you're not crashing all the time.

The bad thing about the Skyray wing structure is that the covering holds it rigid, you have to tweak it to get it straight, and it's always warping up again.  The good thing about the Skyray wing structure is that the covering holds it rigid, and when you thump it hard into the ground the covering bursts and the damage to the actual wooden structure is minimal.

Yep. Here's what happens when you are naive enough to use shear webs and light contest balsa for ribs in a trainer.



If you do use webs, face-mount them so they'll do their job, but pop off in a crash

[Tim Wescott]

True, I "pancaked" it last year, only thing that happened was ripped monokote.

I'll check it out thanks!

Do you guys use wing gigs or something when you're building airplanes?

When I can.  Or maybe "always" if you stretch your definition of wing jig a bit.  I make sure that the LE and TE are held at the same altitude, one way or another.

I prefer a jig that involves holes in the ribs and jig rods.  It makes a nice straight wing, and if you get really long rods from a kite shop you can build the whole wing in one piece, and not pull the jig rods out until the LE sheeting (if you use it) is on.  There's a wing jig design that holds the LE and TE nice and solid, but I don't have one.  On something like the Skyray you can make do with little stands that hold the LE and TE, but you have to custom-make the stands for each wing design.

[RknRusty]

Here's what I call my redneck wing jig. The TE pieces were leftover from a Li'l Jumpin Bean kit, but they fit this sterling Yak-9 perfectly. Then draw a centerline on a square 2x2 balsa log at the same height off the glass as the jigged TE centerline, cut into pieces and block up the LE. Match it's centerline(drawn on its backside) to the block's centerline.

[Tim Wescott]

This is what I used on my Twister, in this thread:



Here's another one, from my oft-delayed Legacy build, showing the "jig rod" method.  The actual jig is pretty redneck -- it's just a couple of 8mm carbon fiber tubes from a kite shop sitting on 1/2" x 1" aluminum blocks.

[Chris Fretz]

What do you guys use to mount a engine on a profile straight?

[Chris Fretz]

This is what I used on my Twister, in this thread:



Here's another one, from my oft-delayed Legacy build, showing the "jig rod" method.  The actual jig is pretty redneck -- it's just a couple of 8mm carbon fiber tubes from a kite shop sitting on 1/2" x 1" aluminum blocks.

Were the holes in the ribs already for use of a rod?

[RknRusty]

What do you guys use to mount a engine on a profile straight?

A ruler. Referenced off the centerline on the fuselage through the drive shaft. Or if the engine is off center, draw a line parallel to the centerline and use it.
First thing you do before building it is draw those lines along the length of the fuse.

[Chris Fretz]

Here's what I call my redneck wing jig. The TE pieces were leftover from a Li'l Jumpin Bean kit, but they fit this sterling Yak-9 perfectly. Then draw a centerline on a square 2x2 balsa log at the same height off the glass as the jigged TE centerline, cut into pieces and block up the LE. Match it's centerline(drawn on its backside) to the block's centerline.

Is that a Brodak kit or the real deal? I have a Sterling Yak but for some reason its flying horrible, always wants to climb in level flight,  an it's all over the place. Turns tighter one way too if I remember right.

[RknRusty]

That's a Sterling. I just got a Sterling Mustang for $50 bucks, so the twins can keep each other company.

[Tim Wescott]

Were the holes in the ribs already for use of a rod?

Yes.  The Brodak Legacy (and many other Brodak kits -- I don't know which ones) all come with jig holes.  If you're scratch-building and you stack-cut the ribs you can do this -- or you can buy rib kits from them.

[Chris Fretz]

That's a Sterling. I just got a Sterling Mustang for $50 bucks, so the twins can keep each other company.

I like Sterling despite what people say.
The Mustang was the first airplane I built an it is always the airplane I fly first. What does your mustang look like, or is it a kit?

Here is my sad Yak-9, now I learned something new I see the trailing edge is warped on it too.

[RknRusty]

Chris, my Mustang is still in the kit box. But it must have lived its life so far in a cool dry place. The wood is in perfect shape. Typical Sterling wood, you could bludgeon someone to death with the fuselage Lol. The Yak was much worse for wear when I got it. The ply was all de-laminated, and the fuselage was so poorly cut I laminated a new one. I'll probably do that with the Stang too, to help it stay straight and, in the case of the Yak, arrest any hairline cracks that might start on one side. I think the Fox .35 might have caused that to happen. I will not use any of the kit plywood, and decide on the rest as I build it. I'll probably start it this Fall. I'd like to use a Max-S .35 on it rather than a Fox.

I still need to make some exhaust pipes. That piece of blue tape has been on it for 3 years now.
Your old Yak looks to be able to fly again without too much repair. I like the silver wing, what is that?

[Chris Fretz]

Chris, my Mustang is still in the kit box. But it must have lived its life so far in a cool dry place. The wood is in perfect shape. Typical Sterling wood, you could bludgeon someone to death with the fuselage Lol. The Yak was much worse for wear when I got it. The ply was all de-laminated, and the fuselage was so poorly cut I laminated a new one. I'll probably do that with the Stang too, to help it stay straight and, in the case of the Yak, arrest any hairline cracks that might start on one side. I think the Fox .35 might have caused that to happen. I will not use any of the kit plywood, and decide on the rest as I build it. I'll probably start it this Fall. I'd like to use a Max-S .35 on it rather than a Fox.

I still need to make some exhaust pipes. That piece of blue tape has been on it for 3 years now.
Your old Yak looks to be able to fly again without too much repair. I like the silver wing, what is that?

Ahh yes I remember that old box. Where did you find it? I don't see them anywhere anymore, sometimes on ebay.
All it is on the wing is Monokote.

[RknRusty]

A friend of mine was thinning out his collectibles and sold it to me. He posted it here and I pounced. I wanted the good twin to my evil Yak-9.
My Yak has Monokote on the wing including the red stars, and silkspan and Rustoleum flat white with clear Lustrekote on the rest. I'm going to paint the Mustang in the Tuskegee Airmen red tail scheme, even though I'm not sure they ever flew the D.
Rusty

EDIT: They did fly Ds later in the war