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Old Mar 28, 2009, 09:46 PM
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Build Log

Building the 55" Comet Sparky


One of my favorite builds as a kid was the Comet Sparky. I almost built a 1:1 for Old Time Rubber R/C, but decided instead to enlarge the model and redesign it from the ground up as a dedicated R/C design.

The new design has a 55" span, 338 sq. in area, and will be flown with 3 ch. using a 2208 Suppo Outrunner on 2 cells for power. Since Sparky is not long on wing area the goal is to build the model as light as possible, and also desided to go with the Dallaire airfoil again since it is such a terrific high lift low speed section.

Meanwhile, the plans are all roughed in, the parts are in hand, and it's time to get the build started.
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Old Mar 28, 2009, 09:50 PM
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Starting with the Bowed Outlines


Construction begins with making up all the bowing patterns from artists foam board, then making up the bows for the wing tips, horizontal stab tips and rudder outline.

For those relatively new to making bowed outlines, have a look in here for a step-by-step How-To; http://patscustom-models.com/Bowed%20Outlines.htm
Old Mar 28, 2009, 09:58 PM
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Getting Started on the Wing


One of Sparky's best features is that long slender wing with its eliptical tip. It's just a good lokking wing.

Construction begins withjoining the inner and outer spar segments. The front and rear spar assemblies are then joined in the center using 1/32 ply dihedral braces.

The spars were then pinned to the board and the wing assembled and glued together. The front spar lays directly on the building board, the rear spar was shimmed up 3/32" to accommodate the undercambered airfoil section.
Old Mar 28, 2009, 10:00 PM
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Moving On to the Other Wing


The second panel was built the same way as the first. The spars wer pinned to the board and the wing assembled around them.
Old Mar 28, 2009, 10:01 PM
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Finishing Up the Wing


Once the assembly was completed, the wing was lifted from the board and sanded to final shape.

PAT
Old Mar 29, 2009, 05:02 AM
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Right-on Pat,
Another one of my favorites.
I must have built Sparky a dozen times as a youngster.
I got some pretty decent flights but I was'nt very good at keeping the weight down on my models back then. Now I can keep the weight down on my models but my midsection is another story.
Although my kit collection is getting impossibly large and my building time has gotten incredibly small, I'm going to have to put one of these on the shelf.
Just let me know when I can get my mitts on one.
Who knows, I might just be able to free-up some time for this one.
You gonna put ailerons, flaps and retracts on it?
Just kidding.
Looking forward to seeing how you cover the area under the wing saddle behind the cockpit.
I had great success with silkspan applied damp.
I'm sure whatever you do will be awesome.
Man-o-man, I can hardly wait.
I'll bet it'll be up for a long time with the boomer thermals here in Tucson.
John (in Tucson)
Old Mar 30, 2009, 06:58 AM
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Pat, It looks great. I wish I knew you were going to build and maybe kit one.
I just finished my own last month.

I would have waited.

Are you adding the ventral fin as on the earlier ones?

Paul
Old Mar 30, 2009, 07:48 PM
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Sparky with rubber power


Looks great Pat. Brings back lots of good memories from the past. Here’s someone else’s Sparky flying at the sod farm last year.
Old Mar 30, 2009, 08:22 PM
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I learned to build models by building several Sparky kits. The local food store kept a supply of Comet kits, mostly the Sparky because it was popular and cheap at $.50. The store owner always included a tube of no name glue. Got the job done but the fumes were strong. A weak fan did circulate the air a bit. The radio was always on while building.

I built most of mine on the bottom a dresser drawer. All the tools I owned were kept in the bottom drawer. The printed wood parts were usually very hard/heavy wood. I didn't know the difference. The included tissue was Red in most of my kits.

Single edged razor blades, Mother's sewing pins, waxed paper, glue, a few pieces of sand paper, some Japanese tissue, rubber, props, clay, old pair of pliers to pound the pins, some odds and ends. I was a good builder but had no clue about trimming to fly.

By the forth or fifth kit I was getting it. Sort of. Mine were built as per the kit except for the landing gear area. I put a few extra scraps of balsa in that area because my landing gear took a beating and tore loose on several occasions.

The best flying Sparky I built was the one I cut the nose off one bay, glued a thin firewall and installed a K&B Torpedo Infant engine.

Chased it once for several blocks on a hot day in July. Landed on top of the ice house. A worker used a ladder and got my Sparky.

I relived that flight many times while growing up. Good times on the cheap.

Not sure of the allure but I am still fond of Sparky.
Old Apr 11, 2009, 12:42 PM
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Getting Back on the Project


After taking the time to wrap up a couple of other more pressing projects I'm finally able to get back on the Sparky and make some headway.

Next up is the fuselage. This is really just a BIG stick frame, so won't go into too much detail. One thing that jumped right out is that the longerons are both over 3' long, so using 36" sticks, scarf joints were need for all the longerons. From there, it's all pretty straight forward stuff, with the exception of the fuselage side frames being different to accomodate the built in right thrust. The difference will be shown on the framing plan to clear up any confusion.
Old Apr 11, 2009, 12:47 PM
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Moving On To the Cabin


The wing saddle is notched into the cabin formers to insure a good alignment. A couple of significant design changes were made due to a potential weeknes in the cabin area that were patched up on the p-type, but will be corrected in the kit.

Then the landing gear was added and the ply doublers and lower former was glued in place. The firewall was also fitted and the rest of the front stringers added.
Old Apr 11, 2009, 12:50 PM
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Finishing the Basic Fuselage Frame


At this point everything is done with the exception of a couple of braces around the cabin to stiffen the wing saddle. From there we'll move onto the tail section.

PAT
Old Apr 11, 2009, 01:15 PM
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Onward and upward.
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Last edited by Pilatuspc12; Aug 30, 2011 at 10:33 PM.
Old Apr 11, 2009, 07:23 PM
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Pat,

Will this be available as a kit soon?

Brian, an EAJ
Old Apr 11, 2009, 09:33 PM
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Moving On to the Tail Section


Got the vertical and horizntal tails built up this afternoon. The rudder is no big deal, just the standard flat plate stick frame with a bowed outline.

Since the horizontal tail is is a lifting stab it build a lot like a wing. The elevator joiner is built up from .056 wire and aluminum tube and built into the basic assembly.

Once framed, the stab assembly was removed from the board and sanded to final shape.


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