*****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

To receive email notices of new posts just enter your email address in the block at the left. It will be confidential, only Google will know!

Thursday, June 18, 2015

Simple Fitting Bending Tool

The 7.2 degree sweep of the Skyote wing creates a challenge in making accurate matched pairs of spar mounted fittings. In the early stages of this project I designed a rather complex but effective ram style bender. You can see this bender in my post of Nov. 28,2007 entitled  "Radius Bender". This bender is capable of producing bends which are very accurate in terms of position on the part and degree of bend and in a repeatable manner.  It is, however" quite expensive and complex and somewhat cumbersome to use.

An upcoming "Group Buy Production Run" of water jet cut parts for other builders has inspired me to develop a more practical method of achieving accurate bending results.

This new method uses a common bending brake similar to those readily available from Harbor Freight or Grizzly, etc..
Anyone building a Skyote needs one of these anyway. This is a 36" brake. There are many options but smaller brakes don't generally have the backbone required to bend 4130.

I used the same 3D modeling software that was used to model the fittings to model a jig (fixture?)  to accurately position the fitting in the brake. The jig assures both alignment and offset of the bend. A sheet metal "Counter" is used give the proper bend radius.
Only two simple parts are required. (1) A sheet metal angle made from 0.032 to 0.050 aluminum to serve as a radius shim over nose of the upper clamping bar to give the proper bend radius. (2) A precision alignment jig designed to position the part perfectly in the brake.  That's it!

 The jig is CAD designed, waterjet cut and the tabs are bent on my precession bender. This creates a pocket or back-stop which accurately positions the fitting.  The up-turned tabs position the jig in the brake.

The  "C" shaped jig provides offset and alignment. The angle provides the proper bend radius.
 This is how the parts fit in the brake, clamped tight, ready to bend. Be sure the fitting is firmly seated into the jig. Of course, the gap between the upper clamping bar and the lower pivoting bending bar must be properly set.

After bending. This approach yields consistent results which is a requirement for matched pairs.

The operator is responsible for achieving the proper bend angle. A simple angle gauge for 97.2 degrees and 82.8 degrees will be provided with the fitting kits.
With a little practice you can get really close every time. Adjusting fittings which are a little over bent is easy. Also, you can C-clamp a stop onto the frame of the brake.
Only one jig is required for the 4130 kit parts because I made small adjustments (0.015"+/-) to all of the fitment models so the the bend offset from the edge of each fitting is identical. This method is considerably faster than my precision ram type press brake.

Tuesday, June 16, 2015

Three Down-One to Go!

Wing number three is now painted. One to go!!
I sure will be happy when its done.

 I am lucky to have a good wife. Julia agreed to let me store a wing on our dining room table for a "short while". Tom Dubes helped me carry it in.

 First try at a logo.  The vinyl material is a close match to the Federal yellow paint but when it is applied over the black paint it changes slightly. I am not certain what I will do to correct it.