*****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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Saturday, December 5, 2015

Ready for the FAA

I failed to get photos of #88 when it was on the scales. The CG is good, a little on the forward side when empty.  The weight came out about 30# higher than I expected! Bummer! Likely a heavy paint job and too many improvements.  I will post some accurate numbers later. 

The FAA estimated "mid December" for the inspection.  I hope it happens before Christmas.

Final Details

These are some last minute details  before calling for the FAA.

Starting with Pete's wing fairing root patterns, Tom refined them and produced a great set of wing root fairings.

The trailing edge worked out to be very nice.

Back to the never ending prime and paint!



Thursday, October 15, 2015

First Engine Run

Today was a good day!We rolled #88 out for its outdoors debut and started the engine for the first time. The engine start up and run went well. No leaks, good oil pressure and CHT numbers. 

Saturday, October 10, 2015

One Step Closer

We fitted the engine cowl and the boot cowl today. It took just a little trimming here and there as this was the first time everything had been on the airplane at once so we found a few small spots of interference.

Only two significant items left to do.  Recover the ailerons and make and install the wing root fairings.

Monday, October 5, 2015


Tom led the way again and we made good progress in getting the wires centered and rigged today. We have not tensioned the flying and landing wires yet but hopefully we can do that without disturbing things too much. We learned how important the center section is in the rigging process.  It must be made right before trying any other rigging.

We used a Bosh GLL3-15 three-plane chaulk line laser which really makes things much easier, especially with the Skyote having zero dihedral.
I didn't get any good photos but if you look carefully you can see the laser lines on the wings.  We were doing the preliminary set up at this point with the airplane sitting on the gear. Better results are obtained with the airplane supported directly by the airframe with the wheels off the floor. 

Friday, October 2, 2015

All Wired Up!

The wings are hung and all wires are installed.
Thanks to Big Tom Dubes for taking the lead in this phase.
Time to get her all rigged up!

Wednesday, September 23, 2015

Almost an Airplane

If I squint a little and use my imagination and if the light is just right I can almost see an airplane!

We hope to hang the upper wings this weekend

#88 will get a new panel when everything is finalized.
We just might be able to move the Trigg Comm and trandsponder up into the main panel and get rid of the sub panel which blocks the view of the fuel valves.

Tuesday, September 22, 2015

Matched Hole Spar First Look!

The "Matched Hole" Spar kit is an out-of-the-park home run!  The spar cap to spar web fit is perfect and the pre-bent spar mounted fittings do the same. With the exception of trimming the spar caps for the tapered tip these photos could have been made 5 minutes from the time the spar components came off the water jet table. The extrusioned spar caps make a much nicer spar compared to the formed spar caps. Wish I had them on #88!

This is a "shorty" demo spar made for ease of transport and show and tell. All of the critical features are retained from the full 9'-6" spar. Just the long sections with nothing but rivets have been eliminated. I created all of the CAD models for these components anand built this exact assembly in virtual space so I had a good idea of what the real thing would look like. Even so I wasn't prepared for how simple and elegant it is when actually in hand

The tapered tip uses features cut into the spar web as a template for trimming the legs of the spar. No measuring or layout of any kind is required. It is "automatic".  I will post more detail on this soon.

Overall View

Spar Root View

Wire Anchor Plate View

Interplane Strut Fitting View

Tip After Trimming and Bending Angles

Saturday, September 19, 2015

Fourth Wing Painted and Top Wings Striped The end is in Sight!

 Well, the fourth wing is finally painted and both top wings have "Cruiser Orange" stripes.
A little vision hiccup kept me out of the paint booth for about three months but all is well now.The stripes turned out nicely. We pulled the tapes at just the right time so the edges healed over nice and smooth.

The lower wings are hung , just waiting on the upper wing stripes to cure. Actually due to schedule conflicts, we likely won't hang the upper wings before late next week. No matter, there are plenty of details to look after.  My hangar buddy and friend Tom Dubes  (that's his RV4 in Team AeroDynamics livery in the background) has been a tremendous help keeping the fires burning while I was down for maintenance.

Much has been accomplished since my last report Mostly by Tom with me helping a little.

  • The elevator and rudder controls rigged
  • Brakes topped up and pressure tested
  • Fuel tanks flushed and leak tested.
  • All avionics wiring completed and tested.
  • Engine breather piping installed.
  • Fuel tanks flow tested (again).
  • Prop mounted.
  • Primer pump installed.
  • Belite fuel gauge  for fuselage tank installed and wired. This uses the new pressure transducer which makes for a very easy installation.

The major items left to do include making and installing the wing root fairings and some re-work on the ailerons which don't fit to the standard of the rest of the airplane.  We will likely wind up with a "matched hole" aileron kit as the result of the rework.

This is a very busy time with much progress being made on the Matched hole spar kit, welded fuselage kits, etc.  I will post as often as I can find the time but it might be a little spotty.

Wednesday, August 19, 2015

Fitting Bender Angle Meter Addition

I remembered that I had an old Starrett Angle Finder with magnetic base and it occurred that it might be useful as an angle indicator while bending fittings. This is the AM-2 Model and sells for less than $20 all over the web.  Turns out it works great!

Here it is attached to the rotating bender bar of my trusty Harbor Freight 36" Metal Brake.
(Harbor Freight currently has the bender on sale for $189.99 normally $279.99 good until 10/17/15. So for about $210 you an have precision fitting bender complete with a "Made in the USA" Starrett angle indicator.)

As luck would have it, when you rotate the bender bar upward to bend the fitting the Angle Meter rotates up giving you a perfect view of the bend angle. There is spring back to deal with so you have to over-form just a bit. Just sneak up on it and determine the correct amount of overbend. Bingo! No more guessing and adjusting later! Sure wish I had this when I bent all of my fittings

Note that my prototype fitting bender jig is not quite wide enough causing the "ear" of the fitting to overlap the tab of the jig. I will make the next one wider to fix this problem.

 The above is a matched pair of two identical spar fittings bent 90 degrees then matched for comparison of the two bends.( In practice, the parts would not be oriented this way.)

Note that the edges of the opposing parts and the hole line up almost perfectly. The shiney spot in the hole is from inserting a cleco.  It has not been drilled up yet.

Thursday, July 23, 2015

A Shocking Development!

About five years back I got interested in finding an alternative to the bungee sprung landing gear shocks. I was looking for something that was more tunable as to preload and spring rate. There were some very interesting shocks being used on sand buggies and other off road atv's but nothing quite fit the Skyote. That led to my design of a shock which used a stack of urethane bushings in compression. This was indeed tunable for preload and spring rate. The design seems to function fine but has not been flown. The only shortcoming was the continuing lack of rebound damping. 

I recently stumbled across an ad in Barnstormers for TK1 Racing shocks that have all of the features I want! Since I was first looking, TK1 has discovered the market for fully functional aircraft shocks for the experimental aircraft and now offers quite a few models. Tony at TK1 was able to assemble a set of shocks for the Skyote using mostly standard parts, just a custom clevis on the top end. 

They are nitrogen pressurized and oil damped on the rebound. They are dimensionally interchangeable with the stock shocks, look good and being all aluminum, weigh almost the same the same as stock. The nitrogen pressure will be adjusted for proper ride height when the airplane is at "Taxi Weight". I hope to be able to give a flight test report in the next few months.

 TK1 Racing shock installed on #88.

Top: Stock shock.
Middle: My design. 
Bottom: TK1 Racing shock.

Installed on the Skyote.

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.

Saturday, May 30, 2015

Yellow Wing #2

Just for the record, the second wing is now in yellow.  Two more to go!

Two brushed coats and four sprayed coats of Ekofill grey primer, Four sprayed coats of EkoPrime white primer. Sanded a minimum of three times  depending on how well I shot the primer. Usually, not so hot! Then five crossed coats of EkoPoly Federal Yellow.  No sanding thank Goodness!

Sunday, May 24, 2015

Landing Gear Complete

#88 is back on its gear along with the floor board skin which must be installed before the main gear. The center section will likely be installed next.

Friday, May 22, 2015

Painting the Main Gear

Grounded! The fuse sadly waits while its landing gear is prepped and painted.

 The gear has been primed with PPG DP-40 epoxy primer and the fiberglassed fairings prepped with hi-build primer. I mounted both gear legs on one arm of the wing rotisserie so that they could be rotated to get to all of the weird angles.

All ready for the final top coats.

 Painting with the brake lines installed was a big PITA. I would not do that again.

Ready to install on the fuselage.

Here the gear strut is prepped and re-primed with DP=40 prior to adding the final top-coats.

Done! I plan to put #88 back on its gear tomorrow.

Covering and painting the fuse on the gear with the engine in place was also a big mistake. I wish I had covered and painted the fuse on a rotisserie. It would have been quicker, easier and I could have done a better job overall.