Balsa USA Citabria Pro 2008 build

Balsa USA Citabria Pro 2008 build
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Balsa USA Citabria Pro 2008 build - 4/27/2008 9:57:27 PM

Posts: 160
Joined: 10/26/2007
From: Hempstead, TX, USA
Status: offline

First post of a new thread, where do you start?

My kit: “Balsa USA” Citabria Pro was purchased Feb. 2008.

I’ll be building this one in a semi scale manner, meaning I will try to make the airplane look somewhat real along with some scale detail. However, the color scheme will be my own and not that of the full scale.

My flying intent will be sport/aerobatics flying. I’ll use it to practice the IMAC basic routine and maybe even try a contest with it. Assuming that I can pull that off then maybe I’ll move on to the sportsman routine. But, Hey, First, I have to build it.

Power for this one is going to be a NIB (1990 version) Super Tigre S90K. Covering will be colored SolarTex. For the painted surfaces I am seriously considering using latex house paint and sealing the entire plane with water based polyurethane. That is a whole new process for me. I’ll do a little bit of kit bashing along the way, which I’ll highlight in this thread as I get there.

I would like to invite anyone that has built, is building, or going to build one of these to jump on in with some post. Would love to see pictures posted of your “Pro’s” finished or in the building process.

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Rick, AMA 115812
WACO Brotherhood #75

RE: Balsa USA Citabria Pro 2008 build - 4/27/2008 10:05:28 PM

Posts: 160
Joined: 10/26/2007
From: Hempstead, TX, USA
Status: offline

I started out with the Motor Mount. This way I can get the firewall drilled and have it ready when the fuselage goes together.

Having access to a CAD program and a little mill time helps me add another dimension to my building efforts. Question is will it pay off in the finished product?

Pictures 1 & 2Using a CAD program I found a way to rotate the engine and mounts so that I will not have to cut any holes in my cowling if I choose not to. By the way, 35° from inverted.

Picture 3I designed the engine mount with three separate sections (5 pieces) to allow me to make changes later on without having to remake everything. The center piece actually has the 1° down and 1 ° right thrust machined into it. Later if I need to change thrust angles, I can remake this one piece and still maintain correct propeller and shaft location.

Pictures 4 -7—Finished results.

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Rick, AMA 115812
WACO Brotherhood #75

(in reply to RICKSTUBBZ)

RE: Balsa USA Citabria Pro 2008 build - 4/27/2008 10:29:46 PM

Posts: 160
Joined: 10/26/2007
From: Hempstead, TX, USA
Status: offline

There are a couple of different things I would like to get info on:

I am trying to find some pictures that show where the aluminum panels end and the fabric starts. Also would like to see rivet/screw detail for panels.

I’d like to ask anyone that has built and flown one of these “Pro’s”, what you would do different if you had it to do all over again? Did you have to add much weight to get it balanced? What engine?

For aerobatic flying how did all the control throws work out? Just from looking at the plans, I am already planning on enlarging the rudder. From what I have found on the internet, this was common on the full scales as well.

Here’s a picture of a uncovered full scale Citabria rudder from the internet.

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< Message edited by RICKSTUBBZ -- 4/27/2008 11:12:05 PM >

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Rick, AMA 115812
WACO Brotherhood #75

(in reply to RICKSTUBBZ)

RE: Balsa USA Citabria Pro 2008 build - 4/28/2008 5:35:12 PM

Posts: 20
Joined: 7/19/2002
From: flyin in the bluegrass, KY, USA
Status: online

Hey Rick,
That is a sweet mount! I've got a Pro I built several years ago that I'm bringing out of retirement. Originally I powered it with a well broken in (read that used) .90 FS. It was on the low side of the power required. I later installed an ASP 1.08 which was way more than enough for the way I like to fly but I really missed the FS sound. I hope to have it back in the air in the next few weeks with a pumped 1.20 OS. Its been in the hangar for 3 or 4 years so I'm going over everything.

quote:

what you would do different if you had it to do all over again?

Glass and paint the belly pan. I covered mine in 21st Century fabric (red) and film (white). It has held up great except for the pan wrinkles.

quote:

Did you have to add much weight to get it balanced?

With the .90 and the 1.08 I didn't have to add weight. I've not checked balance yet with the 1.20. She is a little portly at just under 12lbs. This is the old BUSA design though so I don't know what they've changed that could effect weight.

quote:

For aerobatic flying how did all the control throws work out?

Rolls seem slow even at full over (scale like I guess). Inverted seemed to take alot of down input even though balance checked within range. Maybe a parasol design thing I don't know.

I'm looking forward to getting mine back in the air now that I'm flying some again. This was my first attempt at scale anything and I really like the looks of it in the air.

Good luck with yours.
Dave

(in reply to RICKSTUBBZ)

RE: Balsa USA Citabria Pro 2008 build - 4/28/2008 5:53:56 PM

Kmot

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Joined: 6/11/2003
From: Northridge, CA, USA
Status: offline

I love stuff made in metal and that motor mount is SICK!!

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RE: Balsa USA Citabria Pro 2008 build - 4/28/2008 6:03:24 PM

TJR1

Posts: 245
Joined: 3/20/2007
From: Mobile, AL, USA
Status: offline

I've been wanting to build one of these for some time now and I will be watching this thread with much interest. For me though, I think I'd like to do it as a first attempt at true scale. If and when I do buy the kit, I'll have to decide on power and maybe persuade you to machine me a mount also

!

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RE: Balsa USA Citabria Pro 2008 build - 4/29/2008 2:23:29 AM

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Joined: 10/26/2007
From: Hempstead, TX, USA
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I have been working on drawing my new rudder tonight. Unfortunately I don’t have anything to show yet. Ran into my first scale dilemma

. On the kit, the hinge lines for the rudder and the elevators are the same distance from the firewall. (41 11/16”). On the full scale “Pro” and all the other Citabria’s for that matter the elevator hinge line is further forward than that of the rudder. On the kit the rudder trailing edge stops short in comparison to the elevator trailing edge. On the full scales it is just the opposite. Which was going to work out just fine since I had decided to increase the rudder size anyway. Now I am looking at moving the rudder and vertical stab back or moving the horizontal stab forward.

Thanks to all for the comments on the motor mount. (Kmot)

Dave (acemcduck) I do appreciate the heads up on balance and handling. That lets me know, if I don’t go nuts with something everything should work out. Your 120 ought to drag her around pretty well. Good luck with yours as well.

(TRJ1) This is my first attempt at doing something scale. I think this plane/kit lends itself well for getting some scale experience.

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Rick, AMA 115812
WACO Brotherhood #75

(in reply to TJR1)

RE: Balsa USA Citabria Pro 2008 build - 5/1/2008 3:14:19 AM

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Joined: 10/26/2007
From: Hempstead, TX, USA
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I decided to add 1/2” to the rudder (front to back) . Pictures show the original and the new. Not a whole lot of difference. I am going to redesign the elevator/horizontal stab as well. The hinge line for the elevator will move forward about 1 inch. The counterbalance for the elevator will be enlarged as well to bring it more into scale. This will reduce the area of the stabilizer bringing it more into scale of the full size. It should help with aerobatics, albeit I will loose a little stability.

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Rick, AMA 115812
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(in reply to RICKSTUBBZ)

RE: Balsa USA Citabria Pro 2008 build - 5/1/2008 3:29:23 AM

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From: Austin, TX, USA
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What type airfoil does this plane have? Is it symmetrical or cambered? This will effect the inverted flight quite a bit.

(in reply to RICKSTUBBZ)

RE: Balsa USA Citabria Pro 2008 build - 5/3/2008 2:20:15 AM

Posts: 160
Joined: 10/26/2007
From: Hempstead, TX, USA
Status: offline

I have run into more detail problems in the "scale" department.

I realized that on the model, the horizontal-stab/elevator are positioned a too low on the airframe. To be scale, they need be about level with the top of the fuselage. So, I will try to move that as well.

I will post some pictures to illustrate. I’ll stick a couple of Citabria pics in for grins and looks.

The redesign of the tail feathers is about half done. But, I have to say, I thought I would be cutting and gluing balsa by now.

CrateCruncher,

The Balsa USA Citabria Pro has a true semi-symmetrical airfoil.

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Rick, AMA 115812
WACO Brotherhood #75

(in reply to CrateCruncher)

RE: Balsa USA Citabria Pro 2008 build - 5/3/2008 4:16:09 PM

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From: Conrad, MT, USA
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Cool project. One thing, water based polyurethane is NOT fuel proof, regardless of what you may have read. I had a real mess on my Skybolt using the stuff.

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RE: Balsa USA Citabria Pro 2008 build - 5/5/2008 1:45:23 PM

Posts: 160
Joined: 10/26/2007
From: Hempstead, TX, USA
Status: offline

Limited amount of work done on the “PRO” this weekend. Saturday was all about yard work and Sunday was flying day. Almost pancaked the Smith Mini Plane after a low altitude stall turn. Key word here is almost.

Re-design work on tail feathers is done for the most part. I still have to work out the details on how it will mount to the airframe. Which will not be all that different than the original design.

As to house paint and water based polyurethane, it looks like I will have to build some sort of test piece to hang off an existing plane. This is the first I have heard that it is not fuel proof. I have some material (polyester) test that I wish to do anyway for a future project.

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Rick, AMA 115812
WACO Brotherhood #75

(in reply to Deadeye)

RE: Balsa USA Citabria Pro 2008 build - 5/6/2008 2:57:00 AM

Posts: 41
Joined: 10/18/2005
From: Pemberton, BC, CANADA
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Hey Rick, I'm looking forward to watching your progress, I recieved one of these kits from the family this Christmas, and started building it a couple of months ago, I have just started to apply my covering today, got most of the tail feathers and all control surfaces done so far. I am using coverite 21st century fabric, and pretty much going with the design on the box, as I'm not feeling all that creative at the moment.

I had it all mocked up last weekend with all components installed except the covering, I was really trying to build as light as possible, but it still came in at 11.5lbs before covering, so Im estimating it to be about 12.5 lbs all done. It was quite nose heavy, I think in part due to the engine being a little large, I went with the SPE 26cc gasser which runs great and should, be a nice engine for this plane. I ended up installing the reciever battery about half way down the fuse and the ignition battery as far back in the fuse as I could this resulted in balancing perfect without adding any extra weight, hopefully the covering wont throw it off too much. I had the same problem as a lot of other builders on here with the incedence although I measured from the plans my wing appears to have about 1 or 2 degrees negative incedence, I'm going to put my incedence meter on it to check it once I find it, (Ijust moved recently and still cant find everything), even though the plans say not to, just to see what it says, I'll fly it as as is and make adjustments if needed as long as I dont slam it into the ground that is!! I'll send some pics on another post.

(in reply to RICKSTUBBZ)

RE: Balsa USA Citabria Pro 2008 build - 5/6/2008 3:27:38 AM

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Joined: 10/18/2005
From: Pemberton, BC, CANADA
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some pics

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RE: Balsa USA Citabria Pro 2008 build - 5/6/2008 3:36:11 AM