RE: Balsa USA Citabria Pro 2008 build

RE: Balsa USA Citabria Pro 2008 build
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RE: Balsa USA Citabria Pro 2008 build - 5/17/2008 3:55:45 AM

RICKSTUBBZ

Posts: 256
Joined: 10/26/2007
From: Hempstead, TX, USA
Status: offline

The leading edge of the stab and the stab/elevator hinge spars of this kit are designed to be laminated with two pieces of 3/16 X 3/8 balsa. I am adding a piece of 1/32 ply in between the two. I am doing this because I expect this aircraft to get some abuse. I figure this will add a significant amount of strength and hopefully reduce the amount of flex in the stab and elevators.

Elevator tips are built. There are tabs created with the ply wood that will slide (and be glued) into slots that I will cut in the mating balsa pieces.

I am starting to get concerned about how much weight I have added to the tail feathers. I know it has not been much but adding even a little on the very tail of a plane can cause balancing issues. Don’t want to be hanging any lead in the nose.

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Rick, AMA 115812
WACO Brotherhood #75

(in reply to RICKSTUBBZ)

Post #: 26

RE: Balsa USA Citabria Pro 2008 build - 5/18/2008 7:06:52 PM

WacoNut

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From: Blanchester, OH, USA
Status: offline

Rick I think the gain in strength will outweigh the gain in weight, there should be minimal weight gain from the modification. I have often thought about building this kit, I will be watching

Anthony

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Post #: 27

RE: Balsa USA Citabria Pro 2008 build - 5/18/2008 9:11:57 PM

jjscott

Posts: 196
Joined: 7/11/2007
From: Elm Grove, WI, USA
Status: offline

Does anyone know if anyone sells Balsa USA kits at a discount? A month or so ago there was an ebay seller in northern Wisconsin who was offering Balsa USA kits (a dealer, I believe, but not the company itself). I've searched completed items but can't find him.

Back on subject Rick, you've got a nice build going.

Jim

(in reply to WacoNut)

Post #: 28

RE: Balsa USA Citabria Pro 2008 build - 5/19/2008 7:26:35 PM

RICKSTUBBZ

Posts: 256
Joined: 10/26/2007
From: Hempstead, TX, USA
Status: offline

Have not been able to get back to the “Pro” since Friday.

I forgot to mention in my last post—that I was able to use my tile cutting saw (and diamond type blade) to rip the 1/32 plywood stock. I was quite surprised. Had nothing to loose giving it a try. I actually had stopped by harbor freight and picked up a thin (high speed steel) saw blade to use but it did not fit. Anyway good FYI stuff.

I am considering adding 1/4” or so to the nose to help prevent a tail heavy build. Lots of chances to move battery and radio equipment further back but the front of the plane will get pretty crowded very fast. Just thinking at this point. I’ll decide by the time I frame up the fuse.

quote:

ORIGINAL: WacoNut

Rick I think the gain in strength will outweigh the gain in weight, there should be minimal weight gain from the modification. I have often thought about building this kit, I will be watching
Anthony

Anthony,
I agree the extra strength will be worth the weight and work. Also, just to add, I think this is a neat kit. Lots of possibilities. One can build it right off the plans per the book and have a nice bird or you can go do some bashing, to add a personal touch, with out throwing everything away.

quote:

ORIGINAL: jjscott

Does anyone know if anyone sells Balsa USA kits at a discount? A month or so ago there was an ebay seller in northern Wisconsin who was offering Balsa USA kits (a dealer, I believe, but not the company itself). I've searched completed items but can't find him.

Back on subject Rick, you've got a nice build going.

Jim

Jim
Other than occasional unbuilt kits turning up here or there, I have no idea were to find Balsa USA kits other than from them. They are still a good deal for your buck.

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Rick, AMA 115812
WACO Brotherhood #75

(in reply to WacoNut)

Post #: 29

RE: Balsa USA Citabria Pro 2008 build - 5/21/2008 1:22:14 AM

RICKSTUBBZ

Posts: 256
Joined: 10/26/2007
From: Hempstead, TX, USA
Status: offline

I temporarily glued a scrap 3/8 balsa block to the 3/8 dowel that is to be used to connect the elevator halves in order to hold the dowel vertical, horizontal, the same way consistently……you get the picture.

Picture 1 I cut notches out of the dowel in order to “key” it to the 1/32 ply running through the center of the hinge spar. Used my table saw to do this and cleaned up the inside corners with my scroll saw

Picture 2 –- 1/32 ply has been epoxied to the 3/8 dowel.

Picture 3 & 4 –- The notch in the end of the 1/32 hinge spar and how it fits to the new elevator tips.

Picture 5 & 6 – The tile saw I used to rip the 1/32 ply

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Rick, AMA 115812
WACO Brotherhood #75

(in reply to RICKSTUBBZ)

Post #: 30

RE: Balsa USA Citabria Pro 2008 build - 5/28/2008 2:38:35 AM

RICKSTUBBZ

Posts: 256
Joined: 10/26/2007
From: Hempstead, TX, USA
Status: offline

I did the hinge slots the same as I did for the rudder. I can say with out a doubt, pre-drilling was a plus for the elevator/stab spar since I had the piece of 1/32 plywood sandwiched between the balsa.

When building the hinge spars and stab leading edge I decided to drill some 3/16 dia. holes to try out for lightening purposes. These were put only in the inside piece of 3/16 balsa before they were laminated to the 1/32 ply and the outer piece of 3/16 balsa. Don’t have a scale here to weight them before and after. Mathematically it works out to be a reduction of just over 4 1/8” of 3/16 X 3/8 balsa. (Not much, considering how much stock is on this tail)

The bevels on the elevator/stab hinge spar are 20° and were cut using the same set-up as the rudder.

Before starting the build of the stab I clamped the hinge spar to aluminum bar stock to help keep it strait.

The tabs, grooves, and slots I cut for the elevator tips/counter balance worked out really well. I expect this to really stiffen up the counter balance area of the elevator.

Only a couple more pieces of wood to cut and glue and the elevator will be done. Hope to have pictures of that tomorrow.

Picture
1 - shows the holes drilled.
2 – hinge slotting tool I am using.
3 – finished hinge slot.
4 – 56 holes drilled in 3/16 X 3/8 stock.
5 & 6 – Hinge spar bevels.
7 – stab clamped to aluminum bar.
8,9 & 10 –the details of the grooves and tabs associated with the elevator tips.

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Rick, AMA 115812
WACO Brotherhood #75

(in reply to RICKSTUBBZ)

Post #: 31

RE: Balsa USA Citabria Pro 2008 build - 5/29/2008 2:36:51 AM

RICKSTUBBZ

Posts: 256
Joined: 10/26/2007
From: Hempstead, TX, USA
Status: offline

Well, the tail feathers are a long way from done. But I can say all the sticks are glued together. Aside from the obvious sanding, I have to countersink the hinges and figure out the details of the control horns and flying wires/tail braces. Lots of ideas in my head for the braces and horns but nothing on paper yet.

I will start on the fuselage next.

Picture
1 – You can see the 1/32 ply pieces I used to space the counter balance away from the stab.
2-3 – picture of the stab/elevator on top of original plans (moved forward and back) to show how and what I changed on the shape and size.
4-6 – My wife thought it was the wing.

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Rick, AMA 115812
WACO Brotherhood #75

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Post #: 32

RE: Balsa USA Citabria Pro 2008 build - 5/31/2008 8:14:39 AM

RICKSTUBBZ

Posts: 256
Joined: 10/26/2007
From: Hempstead, TX, USA
Status: offline

First side of the fuse truss is complete.

Before I started building the truss I spliced the 1/4” square balsa for the top longerons. To get a nice fit I stacked the two pieces to splice on top of each other Cut and sanded at the same time making sure to keep both pieces exactly lined up with each other. Then used my aluminum bars and some clamps to glue the splice joint.

Because I decided earlier to have the vertical stab hinge spar extend down and became the tail post of the fuselage I wanted to cut the notches in the back end of the longerons now. Mush easier than trying to do it when everything is put together.

The rest of the truss build to this point was standard stuff. However, I did more or less create a “Frame Jig” for the perimeter pieces of the truss. This allowed me to clamp and/or pin the longerons against something strait. I also used wood glue, carefully applied (except the upright at the firewall it was epoxied) and by doing so I was able to remove the first side without tearing up the wax paper. All of this allowed me to use the same setup for the second side of the fuse without having to build on the top of the first half.

Picture
1- Spliced to longerons
2- Cut for tail post before building
3- How the tail post cuts look after assembly
4- First side finished. Note: the aluminum “jig”.

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Rick, AMA 115812
WACO Brotherhood #75

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Post #: 33

RE: Balsa USA Citabria Pro 2008 build - 6/1/2008 3:07:10 PM

RICKSTUBBZ

Posts: 256
Joined: 10/26/2007
From: Hempstead, TX, USA
Status: offline

Used my table saw table and a long sanding block to clean up both fuselage sides. First placed them on the table the same way they were built (the side that was down when built is down first for sanding). Due to slight variations in material thickness - both sides were sanded evenly until all the uprights and longerons were the same height/thickness. Then the sides were flipped and process repeated just to clean them up.

I decided to do the triangle brace specified by the kit a little bit different. This was suppose to be an 1/8” balsa piece inside the 1/4” balsa corner. As you can see I opted for ply scrap placed on top of (inside of fuse) the 1/4” balsa.

Picture
1 – sanding fuse side
2 – scrap piece being marked for triangle brace
3 – ply doublers in place with new triangle brace
4 – fuse sides nearly ready to start the joining process

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Rick, AMA 115812
WACO Brotherhood #75

(in reply to RICKSTUBBZ)

Post #: 34

RE: Balsa USA Citabria Pro 2008 build - 6/1/2008 10:00:13 PM

WacoNut

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From: Blanchester, OH, USA
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Looking good Rick,
May I suggest you make some gussets out of 1/64 or 1/32 ply to go over the joints on your truss sides. They add virtually no weght and alot of strength to the joints.
Anthony

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Post #: 35

RE: Balsa USA Citabria Pro 2008 build - 6/2/2008 3:03:23 AM

RICKSTUBBZ

Posts: 256
Joined: 10/26/2007
From: Hempstead, TX, USA
Status: offline

quote:

ORIGINAL: WacoNut

Looking good Rick,
May I suggest you make some gussets out of 1/64 or 1/32 ply to go over the joints on your truss sides. They add virtually no weght and alot of strength to the joints.
Anthony

Anthony,
I have been seriously contemplating your suggestion. I first saw this on your WACO post, then again on your Cub thread. I really like the idea, not to mention it looks nice

. Just is, once they are finished (the plane) you don't see any of it

. None the less as you stated sure does add a lot of strenth to the glue joint with very little weight cost. I expect this thing will do a snap or two, not to mention a Lomchevac (spelling?) if I can get it to do them. Extra strength will be good

.

_____________________________

Rick, AMA 115812
WACO Brotherhood #75

(in reply to WacoNut)

Post #: 36

RE: Balsa USA Citabria Pro 2008 build - 6/13/2008 4:33:57 AM