Skybench Skybird

[hobbyaddict]

Well, I looked and couldn't find any build threads on the Skybird, so I thought that I would start a build thread and use it to get some tips along the way. I've kit built a Spirit and Skeeter HLG, assembled an Ascent ARF and done some fiberglass repair on a Darter, so I've got some experience but will be learning to work with some new materials as I go. As you can see I've just started and have put the center sheeting in between the bottom rear and front panel of the inner panel. The next step is to cement the carbon strip to the front spar. Here comes my first question. I've never worked with carbon before and it says to glue the shinny side of the 3/8" strip to the spar. I can't tell any difference in the two sides and the 3/8" strip is actually 1/2". Is there a way to tell the difference as to which side, and is it best to cement the strip to the spar first and use the spar as a guide to cut down the carbon or cut the carbon by itself? I have a bandsaw, jigsaw, sanders, and grinders available to cut it. Is there a prefered tool to work with the carbon?

[schrederman]

First of all, be safe. Work outside with plenty of ventilation or a mask and goggles... or both... I do. Sand both sides lightly and use epoxy if gluing to spruce. Cya is fine if gluing to balsa. Use a chunk of emery board to relieve the ribs if there's an overlap of the spars. I enjoyed my Sky Bird build... hope you do, too.

Jack Womack

[Ray Hayes]

The Shinny side info pertained ( at the time of writing the instructions ) to the carbon I was putting in the kit. The kit now has a thicker and wider carbon with no shinny side.

!/2" wide is what the spar, INCLUDING THE SHEAR WEBS ON THE SPAR SIDES WILL MEASURE. Since wider carbon strips produce stiffer - stronger spars, the 1/2 " wide is stronger than 3/8" wide carbon.

I don't install the carbon until I have the side shears installed ( plywood and balsa ) .

The carbon strips create a bump that will show up in the top sheeting. Make a 1/2" wide sanding tool from hardwood and rubber cement 120 grit sand paper to the hardwood. Use a metal yard stick as a guide tool and sand a grove in the bottom of the top sheeting to accept the carbon strip. Another way to eliminate the bump is glue the top sheeting on and sand away the bump.

And what about the bottom spar/carbon Bump???

I use the sanding tool and straight edge to create a channel in the top of the bottom sheeting. IF YOU DON'T CREATE THE CHANNEL, THE RIBS WILL NOT LAY FLAT ON THE BOTTOM SHEETING DUE TO THE SPAR BEING RAISED THE THICKNESS OF THE CARBON STRIP APPLIED TO THE BOTTOM OF THE BOTTOM SPAR.

These prosedures eliminate messing around filing rib notches and shortening vertical shear webs ( between the spars ) to accomodate the carbon application.

[hobbyaddict]

Ok, thanks Jack and Ray

[hobbyaddict]

Well after having to lay off for almost a week because of Christmas Contata practices and presentations I'm back building. Here are a few more progress shots.

I think that I am going to wait and sand the 1/8" x 1/4 sticks and TE closer to the time when I'm ready to glue on the upper TE sheet. I'll remove the wing from the plans at that time and I think I'll be able to get a sharper TE.

[trident58]

Hobbyaddict,
regarding your comment about a sharper TE: a lot of people will trim off the last 1/4" of the TE and replace it with a 1/8"X1/4" basswood strip. That can be sanded down to a real sharp edge without warping. What you can also do is laminate a thin strip of CF tape between the upper and lower TE sheeting. If you go this route, make sure you sand a bevel into the lower sheeting first.
Jon

[Polkastudio]

Hi Hobbyaddict, keep those pictures coming! I got a SkyBird for Christmas and its next up on the building board. Always interested in pictures and comments on someone elses build.

Thanks, Polkaboy

[hobbyaddict]

Due to company in for Christmas and all, things have slowed down a little bit, but here we have the next step of gluing in all the vertical shear webs between the ribs. Looking forward and seeing the plywood shear webs to be installed next with the second spar and microballoons in the other open cavities between ribs 1-6, I can see how this bird can take a pretty hard launch and not bend much at all.

[hobbyaddict]

Well, we have a little more progress. I'd never worked with microballons so I didn't know quite what to expect. The first time I filled in under the main spar I broke it into two steps and did not put in W3 until after the microballoons had hardened. This caused a little more work because I had to sand the microballoons a little before I could install the W3 shear web. After getting a feel for the process, when I filled the bays under the rear spar, I went ahead and put in W4 & W4A right away. I've also glued in the wing hook base to rib #1.

In the last picture you see the rear alignment tube and some 1/16 balsa setting there for the next step. Ray, I was wondering, is the balsa supposed to go from the top of the rib to the bottom and be glued to the tube as well?

Also, if anybody can tell me, the instructions talk about the brass tubes in the wings are supposed to be long enough to enter into the 1/16 plywood root cap, and then it also talks later in the instructions that the brass tube in the fuse is supposed to be long enough to extend into the 1/16 plywood root cap. I suppose that means they each should reach 1/32 into the root cap from each side?

Also I'm confused where the plans say that you should set up both inner wing panels on a flat surface with the rod inserted before gluing in the brass tubes and rear alignment tubes in the other wing. There wasn't any play in the holes for the tubes, so are you supposed to set them up and measure the diheadral and if it is off adjust the holes?

Your help is appreciated.

[hobbyaddict]

Well, moving on to the outer panel build, I've gotten the bottom spar in and the ribs glued in. I'm working on putting in more of the TE supports.

If anybody happens to have any answers for the questions in post #8, I'm all ears, but I figure it doesn't have much to do with the outer panel, so I'm moving on.

[FoamCrusher]

I can't tell from the photos, but is there at least one hole in each rib as well as the end plate to allow for equalization of air pressure between sections? If not, you may want to add them.

I had a heck of time recovering a wing that did not have the holes, while my ARF Bird of Time was a snap to recover and it had them. As you heat the film over each bay to shrink it, the air inside the section expands. If there is no where for it to go to relieve the pressure, it bubbles up the film and it won't allow it shrink properly.

Great thread. I am bookmarking it for when I build one.

FC

[bobby legue]

All you need is a piece of balsa slightly less than the rib height to attach the tube to. I leave the brass tubes out far enough that after the root caps are epoxied on I can sand them flush. Then debur the tubes with the back side of a #11 blade. You can adjust the holes if necessary but they worked out for me.
Bob

[hobbyaddict]

Thanks Bobby,

So there does not have to be any penetration of both tubes into the root cap? As long as I get the wing tube into the root cap, the tube in the fuselage can be sanded off flush with the fuse?

[hobbyaddict]

Foamcrusher,

I had not done that yet, but thanks for the reminder. I figured I'd take care of all that when I put the spoilers and servos in the wings.

[bobby legue]

Yes!

[socalsteve]

I am right on the edge of getting the Skybird. Actually I trying to decide if there is a reason I might want the Bigbird or BBXL so if there are any thoughts I'd like to hear them.

But on the build, has anyone cut in any ailerons and flaps? Or does the wing design make it not possible?

[bobby legue]

Yes, it can be seen on the skybench website.

[hobbyaddict]

Steve,

I decided on the Skybird because I had been flying a 2M Spirit and competing against bigger birds for about a year now. One day I had a buddy at the field let me fly his BOT 3M and I had the longest flight I'd ever had to that point; with an unfamiliar plane under windy conditions. He works with full scale aircrafts and his advise was to buy the biggest wingspan I could afford. I chose not to make it full house but leave it as RES because our clubs contest are broken usually into the Open class and RES and I wanted to be competitive in the RES and will build a composite for my Open class bird in a year or so.

Here is the link to the skybench site and you can see the flaps setup there under the Skybird information. http://www.skybench.com

[hobbyaddict]

Well, I've got the inner panel ready for joining with the outer panel. I still need to glue in the shear webs in the outer panel though. The outer panel on the plan shows an elevation above the workbench of 6-3/4", but that is with the inner panel raised for the dihedral. Is there a measurement that can be used for the outer panel if the inner panel is flat on the workbench?

[Ray Hayes]

both angles are shown, look at it closely and you will have your answer.

Ray
http://www.skybench.com
Home of Wood Crafters

[StevenatorLTFO]

Is there a measurement that can be used for the outer panel if the inner panel is flat on the workbench?


Ray,

what would the measurement between the red arrows be in this view?

Steve

[Ray Hayes]

Ray,

what would the measurement between the red arrows be in this view?

Steve


I'll remove the dotted line from the next printing since it maybe causing confusion.

Ray
http://www.skybench.com
Home of Wood Crafters

[scarab]

Ray,

is this the correct measurement?

Don

[Ray Hayes]

both angles are shown, look at it closely and you will have your answer.

Ray
http://www.skybench.com
Home of Wood Crafters



The building process for attaching the tip panel to the inner panel is:

place the inner panel flat on the building board

Raise the tip panel ( at the last tip rib ) 6 3/4"

Ray
http://www.skybench.com
Home of Wood Crafters

[StevenatorLTFO]

Ray,

I wouldn't have gotten that answer looking at that drawing, sorry! I would have probably had my high school aged daughter doing all sorts of trig problems to figure out a different dimension LOL (been too long since I was in school, all that calc stuff is long gone from my brain)

Maybe if you leave the dashed line, but label the 6 3/4 to it instead of the other line, might be more intuitive.

I have a Skybird kit to build someday, can't wait to see it in the air!

Steve

[hobbyaddict]

That's ok Steve that's what I was about to sit down and start doing.

[hobbyaddict]

Thanks for responding Ray.

[hobbyaddict]

Well, things have slowed a little bit again while I've been going to ground school to get my Private Pilot license. But little by little we've gotten the inner and outer panel joined.

[KevinSheen]

How did you sand the joint prior to joining them? Any words of wisdom besides carefully?

[bobby legue]

Kevin,
If you are hand sanding the outer panel here is what I do and it works wery well. Put the panel at the edge of your work table with the tip blocked up to the proper height. [6 3/4 inches] . Make sure that the panel is square to the edge and tape or pin in place. use an oversize block of wood to attach your paper to. Now sand the rib face flat using the side of your work table to keep it that way. Just a little at a time and check often.
This method keeps everything square as the table edge wont allow you to sand a lean or curve the pressure of the sanding block. I just realised that you may not have a table with 2x4 or larger sides. If you do your in business.
I did it this way for years with excellent results. Now I use a 12 inch disc sander with an adjustable angle tray and in a second all is perfectly mated.
Does that help?
Bob

[schrederman]

I did mine on a table saw with a very sharp, 80-tooth carbide blade. I didn't have to sand them. The cut was absolutely smooth... Sounds terrible, I know... but it works.

Hi Bob

Jack

[CurtissP40]

How did you sand the joint prior to joining them? Any words of wisdom besides carefully?

When prepping a wing root for a dihedral joint, I typically use my Fourmost sanding blocks with angles ranging from 1 to 8 degrees in one degree increments. They work very well on any wing section that fits on my 5 foot bench. Maybe I'm just lucky, but I have never needed fractional degrees, or a longer bench - yet. ;)

I have a 50" DLG that needed 11 degrees dihedral per wing. In that case, I dusted off my old trig lessons, computed the necessary rise and lifted the tip the appropriate amount for 3 degrees for each wing, and used the 8 degree block. (3 degrees plus 8 degrees equals 11 degrees :rolleyes: )

[hobbyaddict]

The bottom sheets for the trailing edge were sanded to flush with the angle of the ribs and the TE upper sheets were glued on. I then built the spoiler frame and glued on the LE on the inner panel and taped it on until the glue set.

Ray or anybody else that has built a Skybird, correct me if I'm wrong but, the leading edge piece for the outer panel at the ribs 18 an 19, is not wide enough to cover the entire gap, so I'm assuming that in that location you glue a piece to the LE piece to make it wide enough to allow for the extra width of those two ribs. Then sand it all to blend.

[bobby legue]

I had that same issue with mine. I figured it was my fault somehow and centered the LE piece and sanded the shape.
Bob

[hobbyaddict]

Thanks Bob.

I just checked my LE piece against the #19 Rib for the other wing and the LE piece is not even as wide as the front of the Rib, so I wouldn't be able to sand the upper sheeting and make it blend without sanding through the sheeting and into the rib.

[Bolt55]

Noticed this thread went cold a while back. I just got a Sky Bird and may do build log. Anybody else interested in a SB build log?

[CurtissP40]

Noticed this thread went cold a while back. I just got a Sky Bird and may do build log. Anybody else interested in a SB build log?
YES!

ABSOLUTELY!

The sooner - the better - - since I am about to start mine, after a year's diversion. I would like to have mine flyable by February 2009, in time for our club's February schedule specifically for RES planes.

I will certainly contribute - IF I have anything worthwhile to offer!

Curt

[CurtissP40]

<SNIP/>
But on the build, has anyone cut in any ailerons and flaps? Or does the wing design make it not possible?
When I bought my Skybird, I ordered two wing kits - one for RES, the other for full boat control.

When I finally get around to building the full boat wing, I will not include spoilers, since the flaps should provide more control and braking than the spoilers alone.

Comments welcomed.

Curt

[Ray Hayes]

You lucky guys, it is the start of the building season for you, for me that means long hours trying to keep up with Sky Bench kit orders and no build time, for the rest of all of you woody fans ... it means ... time to start building.

Watch out for spending too much time on the internet, it's the number one killer of building time. Enjoy to the fullest the art and pleasure of building a woody.


Three Sky Bird up dates:

Add a small amount to the top and front of the tip panel leading edge from the diheral joint to rib # 22 to accomodate the larger faced tip ribs before sanding the leading edge to shape. Don't sand the ribs down to meet the leading edge, that would distort the airfoil.

Cover the wings with Monokote

Cut the supplied plastic tubing into small pieces and use as guides placed on the inside fuse sides for the wire push rods. They will bow/bend under heavy loads to the stab and rudder. Use silicone glue .. a little dab will do ya .....

Enjoy

Ray
http://www.Sky Bench.com
Home of Wood Crafters

[GDbot]

One of the reasons I am on the Internet alot lately is that my OLY 3 kit has not quite arrived yet. Any day now is my hope. I will be reading ALL the Skybench build threads until that moment,savoring the anticipation, and then I will start taking lots of photos to go with a "Yard BubbOly Bird" hybrid build thread here on RCG. Have been buying some supplies but one I have not made yet is the tapered carbon caps I plan to add to the spars because I didn't know the width of the spar, 3/8ths or 1/2.
Also can't wait for more information about Schred Da Man's new JEFE obsession.
I was leaning heavily towards an Oly 2S, but my only flying cohort out here in the middle of nowhere convinced me to go for the 3, and now I am glad he did, yet even more challenging and rewarding.
OK, I'll butt out of this hijack now, Come on FEDEX, you still have 1 hour left in your day!

[atmosteve]

Noticed this thread went cold a while back. I just got a Sky Bird and may do build log. Anybody else interested in a SB build log?

Sure! :)


I mentioned to Ray in another thread that I would have had my Oly built in half the time if not for the internet, but I was really only joking. ;)

Now my woodie build for this year is done, so I'd love to see another skybench kit build log. I suspect the kits share a lot of similarities.

Hey GD, looking forward to hearing about your upcoming skybench build, it sounds like it will be a bit different to most. :cool:

[schrederman]

Steve,

Your flying season is just beginning, isn't it?

JW

[Bolt55]

Ok. I'll start a new build log on this thread. I did another build log earlier this year for a lighthawk DLG. It was great help to me - and fun sharing the build process with others. I've built an OLY II back in the day and couple of Gentle Ladys. Recently I assembled several DLG's. I'm looking forward to getting back to balsa build-ups. Please feel free to share your experiences with SkyBird and other balsa build-ups.

[Ray Hayes]

See above post on Sky Bench instructions up date, added a thrid up date.

Ray
http://www.Sky Bench.com
Home of Wood Crafters

[atmosteve]

Steve,

Your flying season is just beginning, isn't it?

JW

Jack, It sure has. In fact I am back to work now after snatching two hours off to go and maiden the OlyIII at the local recreation reserve.


I'm starting to think of an OlyIIS, with carbony extras, for the two meter class for the coming years. It would have to take high pressure starts. That or the Miles 2m, or a First are on the shortlist for the 2009 woody project, though the First is a mouldie.
Steve.

[Bolt55]

Step 1 says to pin down "pre-cut inner wing panel trailing edge". All I have is a bundle of 1/2" x 1/4"X 36" balsa stock that looks like its for the trailing edge. But nothing that looks like its "pre-cut". Is 1/2" X 1/4" balsa stock what I use?

Step 3 says to glue in the "center" sheeting - I have 6 pieces of 4"X10" 1/16 sheets that I assume are for the top and bottom 1/16" sheeting. For the "center" sheeting on the bottom there is about a 1 1/8 " gap - do I splice in a piece for the gap - or am I misreading this?

[atmosteve]

Ooops, I apologise the OlyIIS reaches over 2 metres.
Steve.

[atmosteve]

Step 1 says to pin down "pre-cut inner wing panel trailing edge". All I have is a bundle of 1/2" x 1/4"X 36" balsa stock that looks like its for the trailing edge. But nothing that looks like its "pre-cut". Is 1/2" X 1/4" balsa stock what I use?

Step 3 says to glue in the "center" sheeting - I have 6 pieces of 4"X10" 1/16 sheets that I assume are for the top and bottom 1/16" sheeting. For the "center" sheeting on the bottom there is about a 1 1/8 " gap - do I splice in a piece for the gap - or am I misreading this?


Hi Bolt, 1/2"x1/4" doesnt sound at all like the built up wing TE of a skybench kit, usually? they are 1/16" thick sheets that are about an inch wide that you set the ribs into. Sorry, never seen a skybird wing kit, perhaps they are a solid TE, but only 1/2" wide- I doubt it.
One thing I learned with my Oly kit, take a lot of time to put it all together in your mind before you start. Assuming all the right pieces are there, it soons becomes logical.
Steve.

[Wylie Shaw]

Step 1 says to pin down "pre-cut inner wing panel trailing edge". All I have is a bundle of 1/2" x 1/4"X 36" balsa stock that looks like its for the trailing edge. But nothing that looks like its "pre-cut". Is 1/2" X 1/4" balsa stock what I use?

AS STATED B4 THE TRAILING EDGE IS APPROX 1" TO 1 & 1/4" WIDE (1/16 X 1) OR SO....


Step 3 says to glue in the "center" sheeting - I have 6 pieces of 4"X10" 1/16 sheets that I assume are for the top and bottom 1/16" sheeting. For the "center" sheeting on the bottom there is about a 1 1/8 " gap - do I splice in a piece for the gap - or am I misreading this?

THERE SHOULD BE NO GAPS IN THE CENTER WING PANEL SHEETING






Best Regards,


Wylie S.

[Bolt55]

Hi Wylie - thanks for the response. I've attached a picture to show what I'm confused about. The center sheeting I have looks to be 6 sheets of 4"X10"X1/16" - Number "2" on my pic below. Is that what I use and do I splice the sheet to fill the gap that you can see that I have from the pic?

[CurtissP40]

Noticed this thread went cold a while back. I just got a Sky Bird and may do build log. Anybody else interested in a SB build log?

It looks like this thread has gone back to sleep.

Is ANYBODY currently working on a SkyBird?

Does anybody have any words of wisdom on the SkyBird?

Does anybody have anything to say about the fiberglass SkyBird fuselage?

[Bolt55]

It looks like this thread has gone back to sleep.

Is ANYBODY currently working on a SkyBird?

Does anybody have any words of wisdom on the SkyBird?

Does anybody have anything to say about the fiberglass SkyBird fuselage?

I'm building mine. I'll start posting pictures here and on my web site. Have you started yet?

[CurtissP40]

I'm building mine. I'll start posting pictures here and on my web site. Have you started yet?
I will be starting after December 13th - since I will be taking part in an indoor fun-fly on that day and have some fine tuning to do on the planes I will be flying there.

I will probably post some Skybird pictures also - if they show something different than what has already been posted - - - there has been much shown and said about the spoiler wing, so I will not likely add anything there.

I will post pictures of my flying stab, and my fiberglass fuselage build.

Curt

[Bolt55]

Ok, it's probably a middle age brain fart but I'm looking at BalsaAddicts photos and he has installed 1/4" X 1/8" balsa sticks between the ribs vertically at the trailing edge. I can't seem to find these on the plans, in the online directions for the Sky Bird, and my kit did not come with balsa sticks - I do have 1/4" X 1/8" spruce that would seem to work. So my stupid question - do I cut the spruce and use the spruce? See photo:

[John Walter]

Spruce is way too heavy for that application. Stick with balsa.

[Ray Hayes]

Ok, it's probably a middle age brain fart but I'm looking at BalsaAddicts photos and he has installed 1/4" X 1/8" balsa sticks between the ribs vertically at the trailing edge. I can't seem to find these on the plans, in the online directions for the Sky Bird, and my kit did not come with balsa sticks - I do have 1/4" X 1/8" spruce that would seem to work. So my stupid question - do I cut the spruce and use the spruce? See photo:


I wish I had the time to post more to the various Sky Bench build threads on RC Groups. I am swamped with kit orders, so my work days are long, no time for anything else. Sky Bench has a long list of kits, it is not like Tower Hobbies and ect. that are all about receiving and shipping. Sky Bench is all about procurring bulk wood and cutting it into parts, takes a lot of time to produce woody kits.

I think Bolt55 is going to need a lot of coaching on his build, Bobby League was a big help to Sky Bench with his very active postings to Sky Bench build threads, Bobby has passed away.

Bolt55: Here are some steps you should take:

match every part to the plan. For example, the 1/8 x 1/4 spruce you refer to are the tip spars. I don't mean match for correct size, but for you to gain knowledge of where each part in your kit goes. Unfortunately, plans grow or shrink based on two things ... humidity and the accuracy of the digital printing machines that produce the plans. The most accurate printing scource I have found adds a 1/4" to a 48" wing span ( 1/2" per total 100" wing span plan ).

Somewhere in the instructions it says to use the small balsa sticks between the root ribs at the TE, dividing the number of sticks between each wing panel starting at rib one. They are not critical to the strength of the trailing edge because there are several ribs spaced close together in the root section. The bundle of these small pre cut sticks are showing in your pic and I think you used one in the pic.

Perservence will pay off.

Ray
http://www.skybench.com

[merlinmurph]

I think Bolt55 is going to need a lot of coaching on his build, Bobby League was a big help to Sky Bench with his very active postings to Sky Bench build threads, Bobby has passed away.

I missed something - Bob passed away???

Murph

[Bolt55]

Hi Ray,

Thanks for your response. Yes I have one bundle of balsa sticks 1/8" x 1/4" X 1". There are only six 1" sticks in the bundle that are too short. I went ahead and cut my own balsa sticks to size and used those. So as long as I know that the plan is not "exact" I can adapt. Sounds like your busy. Thats good - lots of businesses aren't these days (or the media has convinced them that they're not).

As to this internet thing... I enjoy the interaction with other guys as I go through a build. The ability to share tips and pics and advice over the internet is good for some of us. I know others see it as a distraction or waste of time. This isn't my first build and I always pull everything out and check it to plan - which is why I've had the questions that I have.

Anyways the kit quality is super Ray and I appreciate your advice and any coaching you might have time to offer. My first plane was an Oly II I built back in 1984. I've built several Gentle Ladys and have spent the past ten years with DLGS. I missed working with balsa which is why I bought your kit. Looking forward to getting it in the sky.

Merry Christmas!

[John Cole]

WHAT THE....?? Ray, what's up with Bobby??

John

[atmosteve]

Ray, so sorry to hear this, Bobby helped me via PM when I first recieved my OlyIII kit. He was a real gentlemen that was more than willing to help others and discuss woodie building. RIP Bob, and thanks for your words.

[CurtissP40]

At last I have started on my Sky Bird.

Back in early February, there was a string of postings in this thread about dihedral. (Post #'s 20 to 24, on page 2)

I have taken Ray's comments in #24, and re-drawn the picture.

My drawing is most like that in post #20 - minus the dotted line that Ray said he would remove.

The key thing to note is that the 6-3/4 measurement is relative to the inboard panel at the interface between inboard and outboard panels at rib 16.

FWIW, the angles are about a 5.6 degree dihedral (referenced to the building board) and a 11.4 degree polyhedral (referenced to the inboard panel), for a total of 17.0 degrees at rib 27 (referenced to the building board).

By now, most of you have probably passed this point in the build - but I thought I would post this for the benefit of those who may use the information.

Curt

[CurtissP40]

<SNIP/>Unfortunately, plans grow or shrink based on two things ... humidity and the accuracy of the digital printing machines that produce the plans. The most accurate printing scource I have found adds a 1/4" to a 48" wing span ( 1/2" per total 100" wing span plan ).<SNIP/>Ray,

How can we determine if the Sky Bird drawing sheet we have is accurate?

Could you give us measurements of what the drawing should be?

One measurement the wingspan direction and another in the wing chord direction would be very helpful and ideal.

TIA,

Curt

[Bolt55]

Hi Curt,

I'm about done with the wings. Why don't you just use your ribs as a gauge for your plans? My plans are sized properly.

[CurtissP40]

I opted for the fiberglass fuselage, which came with a drawing for the wooden fuselage and some parts, most of which I have identified - :confused: - except for an identical pair, which are lite-ply and shown in the picture.

By a process of elimination along with laying the parts against the fuselage in a variety of places, my guess is that they are the stiffeners mentioned in the general description on the web of the fiberglass fuselage. This conclusion is consistent with the fact that there is a pair of them, presumably one per side.

If it is, my next guess is that each should be mounted inside so that the top edge follows the top outline of the root rib, and glued with a generous amount epoxy (removing the excess that squeezes out at the edges).

If all of this is true, then at least one issue arises: The inside of the fuselage in this area is not flat - CLOSE - but not planar. So - should the part be sanded on the top edge such that it will fit closer to the top of the fuselage?

Enquiring minds want to know - - - ;)

[CurtissP40]

The kit comes with four 0.007" x 0.5" strips of carbon fiber (2 each of 15" and 21.25" in length).

I can't find a specific reference to a long or short C-F strips - Wherever C-F is mentioned, there is no length qualifier.

One photo shows the short piece in place on the bottom, and another seems to show the longer piece on the bottom - in the same location (I.E. between the inboard long spar and the inboard L.E. bottom sheet.

So - which length should go in this location? Long or short?

Then once that question is answered, where does the piece having the different length go?

[Ray Hayes]

1. I no longer include the carbon in the kit, .007 on a wing the size of
Sky Bird doesn't do all that much to improve strength. Properly built, the
wing is very strong without carbon. I flew the batteries out of my Sky Bird
when it was 200 feet high and need to build a new set of wings. I won't put
carbon in the wings, the double spar is plenty strong.

2. During tow, when a wing breaks due to excessive towing pressure, it is
the top spar that collapses first. Therefore the longest and strongest
carbon should be applied to the top spar.

3. If the carbon is applied poorly, which happens a lot to first timers
gluing carbon to spruce, the carbon will shear away from the spar and then
the spar will break.

4. To test your application of carbon to a spruce spar, glue the carbon to
the spar before installing the spar in the wing and after curing try to bow
the spar a bit ... listen and observe for sound coming from the carbon
lifting off the spruce or visually seeing the carbon raising up.

5. The method I use for wing strength in my kits are the 1/16" plywood
shear web parts glued to both sides of the spars.


.... the plywood parts pictured in above post are optional and can be placed inside the fuse with epoxy at the wing mount and then drilled to insert the brass tubes for the wing rods.

Ray
Sky Bench
http://www.skybench.com

[CurtissP40]

<SNIP/>Why don't you just use your ribs as a gauge for your plans? <SNIP/>Done.

And - I am using shear webs for spacing.

BTW - VERY NICE WORK on your Sky Bird build photos!

One question: In your fig 19, it looks like you are using 3/8" shear webs in the outboard section of your wing. I am on the fence on this issue, as the need for hefty shear webs typically diminishes as they get closer to the tip. However, given the size of the SB wing, more substantial shear webs in the outboard section may be a reasonable modification - especially for a flap & aileron configuration.

Your comments?

Curt

[Bolt55]

Curt - I used 1/16" balsa sheet cut to size as vertical sheer webs on the tip panels - there is no filler. On the inner panels I used 3/8" thick balsa "blocks" as shown in Fig. 8.

[Bolt55]

Hi,

Ok, I've been fussing around with the canopy and hatch blocks and it looks like there might be several ways to shape and install these. Anybody care to share how they did it? Ray has some good pics up on his site for a Big Bird canopy and hatch install which I may end up following. Also, is anybody flying with ballast? If so how are you securing your ballast?

[CurtissP40]

When drawing up a root interface rib for the fiberglass fuselage, I discovered that the Sky Bird airfoil measured at the root differs from the Selig 3014 coordinates. This difference is on the upper surface and starts at about 10% from the L.E. and becomes more pronounced towards the T.E. (See attached drawing)

I am wondering what impact the difference has on flying characteristics.

[Ray Hayes]

Check your work, the blue line is wrong, there are no 3014 ribs in any Sky Bench kit that look like the blue line.

Everyone that has built any Sky Bench kit using the 3014 airfoil knows your blue line is incorrect.

Ray
Sky Bench
http://www.skybench.com

[CurtissP40]

Check your work, the blue line is wrong, there are no 3014 ribs in any Sky Bench kit that look like the blue line.

Everyone that has built any Sky Bench kit using the 3014 airfoil knows your blue line is incorrect.

Ray
Sky Bench
http://www.skybench.com
Whoa!

Ray,
it was not my intention to strike a nerve, which seems to have happened. All I wanted to know was what, if any, impact the deviation from the 3014 has on performance.

And now, I am confused. I don’t know what airfoil I have.

I did check my work, and it is correct.

• The blue line is a full scale trace of the scan of the root rib in my kit. My scanner resolution is 300 DPI which is more than adequate for this purpose.

• I went to the University of Illinois airfoil database and compared their 3014 coordinates with those on my system. They match.

• The “official” 3014 coordinates (the red line) were imported into my CAD program, and scaled up to match the Sky Bird root rib trace and scan. Clearly, the coordinate set does not match the root rib trace (the blue line).

• The CAD graphic was printed full scale, and ribs from the inboard section of the wing were physically laid on top of the printed blue root rib outline. They match, allowing for structural details where appropriate (sheet covering, spar notches, etc)

• The attached graphic shows the Sky Bird root rib scan as a photo, the blue root rib trace, and the red UI coordinates for the S-3014.

Given that the graphic matches all ribs of the inboard section of the wing, is, in my opinion, sufficient proof of accuracy.

Your statement that “there are no 3014 ribs in any Sky Bench kit that look like the blue line” is true. The ribs in my kit do not completely follow the 3014 airfoil; most of the upper profile is something else. The blue line is NOT wrong; it is the outline of the airfoil I received in my Sky Bird kit.

Ray, I really don’t care what the airfoil is, as long as the Sky Bird flies as represented by all that you and your many customer/user/supporters have said on the web. The 3014 was not a factor in my decision to obtain the Sky Bird.

Respectfully,
Curt

[allanp]

Was there ever a resolution as to the true airfoil of the Skybird ??
Allan

[CaptAhab]

:rolleyes:

[allanp]

Okay,just finishing up my Skybird wing. I can see now why the carbon strips were deemed unecessary,spar system is more than adequate.
Ray, if you're out there do I remember correctly that several years ago you were flying with just 1 wing rod installed ? If so what do you think would be the outcome of replacing the 2 steel rods with 2 carbon ones (Without getting to technical).
Thanks in advance
Allan

[Ray Hayes]

Okay,just finishing up my Skybird wing. I can see now why the carbon strips were deemed unecessary,spar system is more than adequate.
Ray, if you're out there do I remember correctly that several years ago you were flying with just 1 wing rod installed ? If so what do you think would be the outcome of replacing the 2 steel rods with 2 carbon ones (Without getting to technical).
Thanks in advance
Allan

Allan,

I'll be building another Sky Bird this year without carbon applied to the spars. I'll keep the double wing rod joiner system and use two carbon rods. I will use the two steel rods if flying in winds over 15 mph for added weight (ballast).

One steel rod handled launching on really strong AMA winches. The winches used at the AMA LSF NATS are sized for short tow lines, unbreakable on tow, molded Unlimited size sailplanes.

Wishing you many hours of joy flying your new Sky Bird, it's a great flying sailplane.

Anyone ordering a Sky Bird kit can swap the steel rods for carbon, make a note on the order. My web site has carbon and steel rods for sale.

Ray
Sky Bench
http://www.skybench.com

[allanp]

Thanks for getting back to me so soon. I'll call tomorrow and order a couple of carbon rods. It'll be awhile before I get it in the air as I still need to vacuum bag my center section !!! I'm putting the wing on an Onyx fuse which has "top mounting",so I'm bagging a 3" wide bolt on center section as a carrier
Allan

[Ray Hayes]

Thanks for getting back to me so soon. I'll call tomorrow and order a couple of carbon rods. It'll be awhile before I get it in the air as I still need to vacuum bag my center section !!! I'm putting the wing on an Onyx fuse which has "top mounting",so I'm bagging a 3" wide bolt on center section as a carrier
Allan

Best way to catch me these days for ordering is order by email, fax or the US Mail. I spend my days at the saws in the shop or lately shoveling snow to keep a path open. Global warming is currently on a short vacation in my area.

I like your center carrier idea, should work just fine.

Thank you,

Ray
Sky Bench
http://www.skybench.com

[StevenatorLTFO]

How much weight do you save by changing out the two steel rods with two carbon rods? I might be interested!

Steve

[allanp]

My steel rods are right at 9 ounces total

[StevenatorLTFO]

Think carbon would be what, half of that maybe? I'm just wondering if its worth plunking down 40 bucks for a couple of carbon rods....

[FoamCrusher]

The one Ray sent with my Oly III is 215mm x 8mm and is 16 grams.
(A little short of 8.5" x 0.312" and is 0.5 oz)

FC

[rzorro]

I have the same question Bolt 55 had in #50. My Skybird kit contained (6) of the 1/16" x 4" x 10" sheets he described as #2 in his photo. I forecast one for the top and one for the bottom of each inner panel. That would account for the use of four of the six sheets. Are we to cut up the two remaining sheets to fill the 1 1/8" gap that Bolt55 referenced and that I am similarily experiencing?

[rzorro]

Answered my own question: You have to splice a piece in to fill the gap. The splice can be seen on this Skybird build log:

http://www.aerosente.com/sky-bird-build-log.html

[Bolt55]

Been making slow but sure progress on the Skybird. This is my first time back in a long time doing a balsa build-up so I've been taking it slow and learning/relearning stuff I knew 25 years ago. I'm about to start covering the bird and will hopefully have a maiden in the next week or so. My last several builds (assemblies?) were carbon/kevlar DLG's from RC Builder and Maple Leaf Design. I have to say that I really enjoy being able to build again and seeing a stack of balsa turn into a flying machine. Here's a pic of my final dry fit before I start final sanding, assembly and covering. Ray this is a great kit!!!!!

[rzorro]

I am at the point where I am about to begin the spoiler installation. I think Bolt55 used Dymond 4.7s, one in each wing. My local hobby shop carrys Hitec servos. They recommended the Hitec HS-65HB. Whereas the Dymond advertises 15 lbs of torque, the Hitec advertises 25 lbs. Cost is a push at $25 per copy. Any recommendations or advice?

Also, if these Hitecs are as capable as they are advertised to be, would I or would I not want to use them for the rudder and the elevator?

[Bolt55]

Rzorro - unless you're planning on being really nutty I'm not sure it matters much from a performance standpoint. I'll be using mine for landing mostly which doesn't require much oomph. If you're in a big time thermal and can't get out I can see where there might be a performance issue then. I think Ray flies his without spoilers if I remember right. Either way I wouldn't sweat the servo selection.

[allanp]

I'm using HS-55's on the spoilers.Weight is not really a factor and you can find "new" HS-55's on ebay for about $13 each.I think RCsuperstore is the seller,last set I bought was delivered in 3 days

[rzorro]

If the HD-55s are good enough for the spoilers are they also good enough for the rudder and the elevator, or, what would you recommend?

[Ray Hayes]

If the HD-55s are good enough for the spoilers are they also good enough for the rudder and the elevator, or, what would you recommend?



For the rudder and elevator, it is all about torque and gear strength.

I use hd 85 metal geared, there cheap on ebay, etc. Rocketman on ebay is a cheap scource. But, check with your LHS, they need your business if you want them to stay in business. The small amount you might save will be lost to shipping cost. If you take care of servos, they last a long time.

Ray
Sky Bench
http://www.skybench.com

[Ray Hayes]

Been making slow but sure progress on the Skybird. This is my first time back in a long time doing a balsa build-up so I've been taking it slow and learning/relearning stuff I knew 25 years ago. I'm about to start covering the bird and will hopefully have a maiden in the next week or so. My last several builds (assemblies?) were carbon/kevlar DLG's from RC Builder and Maple Leaf Design. I have to say that I really enjoy being able to build again and seeing a stack of balsa turn into a flying machine. Here's a pic of my final dry fit before I start final sanding, assembly and covering. Ray this is a great kit!!!!!



Good looking tooo .

Ray
Sky Bench
http://www.skybench.com

[allanp]

I agree with Ray. 85's are fine for elev/rudder. I've used them for so long I can almost change the gears with my eyes closed :>). You put them in a set of flaps and eventually you'll strip out the gears.

[dwells]

But, check with your LHS, they need your business if you want them to stay in business.Ray
Sky Bench
http://www.skybench.com

Thanks for that Ray. We need to support all of our local small businesses this day and time. They count on us and we count on them :) .

[Ray Hayes]

Thanks for that Ray. We need to support all of our local small businesses this day and time. They count on us and we count on them :) .



Oh Oh, don't get me started on LHS.....

I said to the owner of our local hobby shop " you don't have a single sailplane kit on your shelf" his reply " am I suppose to have". He is the VP of the local sailplane club. Please don't ask what he flys.

Ray
Sky Bench
http://www.skybench.com

[Ercoupe Ed]

Hi Ray!
I was in "said" LHS the other day and he showed me the "new wing"( only one of the two wings) he bought for his sailplane which shall remain unamed, .All I can say, that single wing could have bought several really nice kits!
You are correct, there is not one single sailplane kit in the store.
He doesn't even have a decent selection of balsa, spruce, or anything else.
If you're not into RC cars or Helis, you're in the wrong place!

[Ray Hayes]

Ed,

I hope you to see you on the field March 29th, first club monthly, bring a 2m and join the woody group of flyers.

All hobby shop,s inventory go with what is hot, they have to pay the expenses.


Ray
Sky Bench
http://www.skybench.com

[rzorro]

Guess I am fortunate to live in Sacramento. There is a LHS here known as RC Country. Absolutely full service. If they do not have it, it does not exist. Prices were very comparable to the internet. I saved the shipping cost, helped out a local merchant, and kept the tax dollars in the community.

Bought an Hitec HS-55 to actuate the spoiler. The Skybird plans describe a much larger servo mounted aft of the main spar and aft of the spoiler. It seems however, that given the tiny dimension of the HS-55, it could easily be placed forward of the main spar in between ribs 9 and 10. Looks to me as though if it were mounted directly to rib 9 or rib 10 that the servo arm would run down the centerline of the bay. A simple linkage could then pass through a small hole drilled in W1. In such an installation, the wire to the servo could then be concealed between the top and bottom sheeting for what would seem to me to be a more sanitary installation. An inspection panel could be cut into the bottom sheeting, moncoted over, and later cut open if necessary.

Is there a benefit or a detriment to mounting this servo forward of the main spar?

[schrederman]

In my opinion... You are inviting wing flutter and catastrophic wing failure by interrupting the D-tube integrity. I would definitely keep the D-tube in tact and mount the servo behind the spar... Or actually I mount all of my spoiler servos in the nose... but that's just me, and, just my opinion.

Jack

[seanpcola]

Not too far off topic:

Tribute to Jack!

I was going through some photos on my PC today and ran across this shot of Schrederman's Skybird.

[schrederman]

Yeah, BABY!!!

I miss her...

Jack

Sorry... liquid diet of 4 Margaritas... That with a gimp leg from Vietnam about 40 years ago, and I was pretty well stumped for anything else to say :eek: :p :D And the last one had teeth... The bartender got a pretty good tip... :cool: