*****Skyote #88 gets Bronze Lindy for "Airventure-Oshkosh 2016 Plans Built Champion"******

October, 2007

Welcome to "Skyotelog", the build record of Skyote #88. I assume that you are familar with the Skyote biplane. If not, you should visit http://www.skyote.org/ for a complete introduction to this unique but elusive biplane.

The posts are presented in reverse chronological order (newest first). Or you can click on one of the "Labels" to see all of the posts concerning a specific topic. Click on any photo for a larger image.

All my building experience is limited to Van's RV's so I have no experience with building tube and fabric or "plans building". I have much to learn so take everything I write with a grain of salt and reasonable skepticisim.

I do not intend to follow a "traditional" path for the construction of #88. I intend to employ low level technology and $ to reduce the construction time and difficulty where possible and practical. By low level technology I am referring to CAD, laser, waterjet, CNC. For example:

  • I have purchased a complete wing spar kit from Jerry Kerr.
  • A rib kit from Mr. Bartoe.
  • Brunton Flying Wires and Drag wires from Harvey Swack.
  • CNC profiled tube kits for the fuselage, tail feathers and landing gear from VR3.

In addition I have converted all of the wing fittings, brackets, links, lugs etc. to CAD and had them cut by water jet. I have designed a laser cut wing spar drill template/jig which positions the five spar components so that all of the holes can be drilled in a complete spar as an assembly. I plan to continue converting as many parts as I can to CAD so that I can reduce the "hand-made" components to a minimum.

Note: As of June 2015 I have over 100 CAD files which provide 600+ water jet cut parts for the Skyote.

While it takes a little time, converting the design to CAD is a great way to truly understand the drawings. plus a huge amount of information has been extracted from the rather complex drawings. This can be a great help to others in understanding and interpreting the design.

The Skyote is uniquely suited for conversion to CAD in that a "computer" was used in it's original design. I have read that Mr. Bartoe used a HP calculator to "compute" the design and dimensions of the Skyote. The plans show all of the critical dimensions to three decimal places for X,Y and Z axes.

Amazingly, when I put the design into CAD the resulting 3D models agree with Mr. Bartoe's thee decimal place dimensions about 99.9% of the time. I have found one discrepancy but less than 0.030"!

If you want to build your Skyote as cheaply as possible, or if you enjoy handcrafting the same parts over and over again then my approach to building is not for you!

If you want to build your Skyote in the minimum possible time with highly accurate parts then this approach may be the answer. I personally get a lot of satisfaction out of organizing the project so that it can be produced accurately. Hopefully some of this work will prove useful to others in the future.

Comments are welcome. I will respond as time permits

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Thursday, January 27, 2011

Center Section Handle

It would be really helpful to have something to hold on to while I coax my 70 year old bones into the cockpit. The trailing edge of the upper wing center section seems to be a good location. One possibility is to replace the 3/8" steel tube trailing edge with combination trailing edge/handle cut from 1/4" aluminum plate. This would allow the handle to be incorporated into the trailing edge and also provide a better interface for attaching to the ribs. I made a prototype from 1/4" plywood and it looks like it will work okay. The middle ribs will be cut so that the upper flange of the ribs laps over the aluminum plate.

I decided to add some tabs to aid in attachment to the ribs. The final part was water-jet cut from 1/4" 6061-T6.

Center section ribs marked for Cutting.

Cutting with an abrasive wheel worked well.

The handle/trailing edge is now in the final position flush with the upper surface of the ribs. The next step will be to install 0.020" skins to tie the handle to the center section ribs and the aft spar.

Monday, January 10, 2011

Fabric/Painting Test Panel

With the covering/painting phase of the project on the near horizon I have started thinking about the alternatives. I have attended EAA workshops for both TIG welding and fabric covering. The welding class convinced me that I would never reach the skill level required to do a top notch job on the Skoyte fuselage structure. The fabric school, however, convinced me that I have a good chance of doing an acceptable job covering the Skyote myself. I have participated in a couple of covering jobs since the workshop, both using the PolyFiber system and PolyTone paint.

I have also studied the line of waterborne adhesives and paints offered by Stewart Systems. I certainly like the user friendly qualities of the waterborne products. Stewart also has an excellent set of DVD's which illustrate the covering and finishing process in great detail. I think they are worth watching no matter which system you choose. You can go to: http://www.stewartsystems.aero/ or you can go to YouTube and enter "Stewart Systems" to see the videos.

I decided to make up a test panel and cover and finish it with Stewart products. This will give me a good comparison of the two systems. I am leaning toward the Stewart products but I want to have a little more experience with it before I make the final decision.

I glued up an imaginary airfoil panel using some plywood scraps and other junk. It is about 20"x20".

Stewart Systems Ekobond adhesive is blue/green in color. Unlike Polyfiber Polytac adhesive it has no oder. I covered this test panel in the kitchen during a recent snow with no complaints from my wife!

I am keeping up with the uncovered, covered, primed and painted weights of the test panel.

The panel in the photo below has two "cross-coats" of Ekofill primer/filler/UV barrier applied by brush. The next two coats of Ekofill will be sprayed. The color is actually a charcoal grey.

Two coats of EkoFill white provides a good base for the "Federal Yellow" EkoPoly topcoat.

Four "cross-coats" of EkoPoly gave good coverage for the final top coat. The EkoPoly gives a nice high gloss finish. I got just a little bit of orange peel. The small test panel didn't allow much opportunity to experiment with gun settings but I am only off about one click from ideal.

Friday, January 7, 2011

Wheel alignment completed.

The wheels and axles were were reinstalled. Skyote #88 now has zero toe-in when it sits in the three point position.

The 1.8 degree axle correction is visible in the photo below. This shot is from above the right wheel with the airplane facing to the right.

Wednesday, January 5, 2011

Toe-in Correction Contd.

Rather than use shims to correct the toe-in problem we decided to machine the face of the axle flange to give the same results. This was done by holding the axle in a vertical chuck and tilting the head of the Bridgeport 1.8 degrees. A fly-cutter was then used to face off the axle flange. Robbie Grove confirmed that these axles are way over built for the Skyote application. A maximum of 0.062" of material will be removed from the flange.

We used a digital level to check the angle of the milling head.

Axle held in vertical vise mounted on the BridgePort table.

Fky-cutter pass in progress.

The photo below shows the 1.8 degree angle on the face of the axle flange. The axles will be reinstalled later this week. The toe should now be zero in the three point attitude. Any further adjustments can be done with shims which are available from Grove Aircraft.

Tuesday, January 4, 2011

Landing Gear Progress

The next step is to transfer the axle flange hole pattern to the brake torque plate flange.

Before drilling, the airplane was put in the three-point attitude and the adapter flanges were aligned to vertical. This will allow toe-in to be adjusted with a simple wedge shim or a wedge cut on the aluminum axle flanges.

The torque plate flanges were drilled using the flange adaptor as a guide.

After drilling the Grove axles were temporarily installed.

With the wheels installed, the center-line of the airplane was laid out on the floor.

A four foot straight edge was aligned with the brake disks to establish the actual toe dimensions.

Each wheel was within a tenth of a degree of 1.8 degrees toe-in with the airplane in the three point attitude.

The aluminum axle flanges will be machined to give a 1.8 degree toe-out correction for each side. This will give zero toe in the three point attitude and a little toe-out as the tail comes up.