*****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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Sunday, November 15, 2009

Trim Tab

Nose Up Trim

Neutral Trim

Bottom View

I decided to utilize electric elevator trim. The RAC T4-5 trim servo is small enough to fit with-in the horizontal stabilizer making a clean installation. The tab and the tray for mounting the servo are made from carbon fiber.

The T4-5 servo has no trim position indicator but I can either set the trim tab position during the preflight walk around or just look over my shoulder during the pre-departure check list. In-flight trim adjustment is always made by trimming off any undesired stick forces.

Sunday, October 18, 2009

Comm Antenna

I have been researching antennae suitable for fabric airplanes. It is difficult to find anything approaching the ideal location/orientation for the comm antenna. I first looked at the 1/2 wave dipole antennae from AAE. I then discovered the Miracle Air Whip antenna which is my choice of the moment. I plan to provide mounting points for 2 or 3 alternate antenna locations/orientations prior to fabric covering. Then I can easily experiment to find the best position.


Saturday, October 10, 2009

Possible Paint Scheme

My good friend Gardy has a neat airport bicycle which is painted in an unusual gray and yellow paint scheme. I never would have thought of that combination but it actually looks good on the bicycle. Here's how it might look on the Skyote.

Hawkeye thinks it looks better with no stripes and big numbers. It does have that vintage look.

The last biplane I had was red all over. I don't recall seeing an all red Skyote. Not bad!

Thursday, October 1, 2009

Head Rest

The fiberglass head rest is complete. We made it extra strong in case someone sits on it climbing in or out. Dale had suggested that we use it for storage. It's a good idea but if we keep adding details we will never finish!

New Strut Design - First Look

Got a chance to fit the the new design landing gear compression struts yesterday. All-in-all I was very pleased with the first look. We just used a kluged-up mixture of urethane bushings to see how they reacted. The amber bushings are of soft durometer and the blue are somewhat harder. You can see the bulge in the amber bushings yielding about 1/2" of compression. We did not use any pre-load of the bushings but some will be required. We won't be able to choose the proper durometer, number of urethane bushings, and preload until the weight of the complete airplane including pilot and fuel can be applied.

This strut design provides the following features:
1. Tunable "spring rate" and possible progressive spring rate.
2. Adjustable preload of strut.
3. Adjustable ride height.
4. Fail-safe relative to bungee breaking.
5. More compact than bungees.
6. Much simpler to build compared to the bungee strut.

As a matter of interest, the left strut in the photos is set up for maximum spring rate and zero travel as it has no bushings. Might be a little on the "hard" side!

Sunday, September 13, 2009

Throttle Quadrant Refinements

The throttle/mixture quadrant has continued to undergo minor refinements. Specifically, all of the phenolic friction washers now have anti-rotation tabs. Also, the anti-rotation pin through the shoulder bolt has been replaced by a stainless steel tab welded to the head of the shoulder bolt. This makes assembly and disassembly much easier,

Rather than welding the assembly mount to the fuse diagonal, the assembly is now held in place by a two-piece clamp collar. This allows some adjustment of the position and makes removal for maintenance or modification more convenient.

Sunday, August 30, 2009

Throttle/Mixture Quadrant Completed

Eventually you have to quit designing and cut some metal! I decided I had reached that point with the throttle/mixture quadrant so I machined up the latest version this weekend. I haven't drilled the attach holes for the throttle and mixture cables yet as I want to confirm the correct position with everything in the airplane. The paper pattern is still on the back side of the levers and shows the likely position of the attachment holes for the control cable ball ends. Also, black and red spherical knobs will be pressed into the ends of the handles when they arrive.

This design works on the same principle as Pete's design using bellville washers but has been modified to include the mixture control as well as forward stops for both throttle and mixture. I will likely add a small lever to the friction adjust knob when I can determine the correct location so that the lever will wind up in the correct position for easy adjustment.

The action is good and smooth with the friction adjustment being fairly linear through about 1/4 turn of the friction adjust knob. Each of the controls is isolated so that movement of one control does not affect the other control or the friction setting.

Saturday, August 22, 2009

Cowling Progress

Dale has continued to pound metal and as a result the cowling is really taking shape. Forming the "eyebrow" cooling ducts has been quite a challenge but they are almost finished. We used a fiberglass cooling duct supplied by Jabiru as a model but the duct we used has been replaced by a later model which gives "better cooling". Hopefully this design will work okay for the Skyote.

Throttle Quadrant Re-Do

I built a model of the previously proposed "pony brake" style throttle quadrant which was less than satisfying in relation to the smoothness of the action. As a result I have gone back to a design much closer to Pete's original design. It uses a stack of Bellville washers to develop the friction when compressed by the knurled knob. A mock-up of this arrangement gave very smooth action so this will likely be the final design.

This part is made from 1/4" 4130 and welds to to the diagonal fuselage tube in the appropriate position. It provides the basic mount for the quadrant and provides the anti-rotational anchor for the shoulder bolt which serves as the pivot for the throttle and mixture levers. The shoulder bolt and the bellville washers came from www.mscdirect.com and the 1/8" phenolic for the friction washers came from Aircraft Spruce. The levers are fabricated from 0.070" titanium and the knobs from 6061-T6.

Tuesday, June 23, 2009

Nose Bowl--One More Try

The nose bowl is getting close. This shape seems to work better.

Sunday, June 21, 2009

Engine Cowling/Nose Bowl

Here's the first stab at the cowling/nose bowl. We are now trying to reshape things to let the cowling and nose bowl flow together with out the bump at the junction. Cowling a "first time" engine is lots of fun. Looks like it will take about four attempts to get it right.

I had originally intended to use the same nose bowl/spinner as Pete Bartoe did on his airplane. Unfortunately, it just did not work out well with the Jab engine. Also the spinner combined with the 6 cylinder engine was starting to make the nose look a little long. A rounded nose bowl with a "skull cap" spinner will help keep the nose in proportion

Thursday, June 4, 2009

Hanging the Engine

We hung the engine on the firewall Saturday afternoon. Now begins the process of finding a home for everything. Unfortunately, it looks like the Jabiru exhaust system is going to require significant modification.

The nose bowl ala Pete Bartoe also has some difficulties jiving with the Jab engine. We may revert to a round style nose bowl like Hawkeye/Dave Novak.

Sheet Metal Progress

Some progress has been made in finshing the boot cowl and cockpit surround. These pictures were made 5/30/09. Everything is pretty well fitted and fastened so it is time to move on to the challenge of the firewall forward.

Saturday, April 4, 2009

Boot Cowl

The boot cowl is beginning to take shape. We plan to use flush riveted hidden hinges to attach the cowl and eliminate most visible fasteners.

Wing Tank Fuel Gauge

The fuel gauge for the wing tank was made by cutting off a "Stearman" style gauge from Aircraft Spruce.

Monday, March 16, 2009

Throttle Quadrant

If you have ever set in the cockpit of a Skyote you know that space is at a premium. In some Skyotes the throttle/mixture controls become knee knockers. I originally considered using panel mounted push/pull controls to keep them out of the way. I finally decided that panel space was too valuable to devote to throttle/mixture so I decided to use quadrant controls but minimize the intrusion into the cockpit. I came up with a compact quadrant design that works on the "pony brake" principle to provide friction adjustment.

In operation the adjustment knob squeezes the split tube down on the cylindrical bodies of the two flanged bushings ( blue and orange parts). A 1/4" flat head through bolt holds it all together but it is not shown as I am just too lazy to do it! The ends of the bushings are machined to receive the flat stock throttle and mixture handles. Moving the handles causes the bushings to independtly rotate against the friction of the split tube. The split tube will be welded to the diagonal fuse tube near the pilot's left hand. The throttle control cable will actually be outside the fuselage tubes in the area provided by the stringers. This will hold the cockpit intrusion to a minimum.

A version with handles rather than knobs.

Friday, March 6, 2009

Turtle Deck Progress

The turtle deck is beginning to shape up. We made the forward deck skin somewhat longer than the plans to accommodate an extended headrest ala Hawkeye's Skyote. I also plan to install the windscreen in the aft position per Hawkeye's recommendations. Dale Doane is responsible for the beautiful woodwork!