SkyoteLog

Tail Feathers Covered

2012-01-01T10:28:00.020-05:00

In mid December I set a goal to have the tail feathers completely covered before the first of the new year. I just squeaked under the wire, completing the covering at 9:00pm, Dec. 31. This may be the first time I have ever completed a Skyote task on time!

Carbon Fiber trim tab in place.

The following are photos of some of the details.

One side of the rudder covered.

Forming the seam for the second side.

I forgot to get a picture, but when the fabric is shrunk, cuts such as the one around the rudder horn create quite a gap. I used a piece of 0.020" aluminum to create "close out plates" around the horn and hinge.

The aluminum sheet assures a clean, crisp, stable edge around the cut.

This was also done at the elevator and rudder hinge cuts.

The tip of a hot soldering iron was used to trim the fabric to the edge of the aluminum.

The soldering iron was also used to create holes for the rib stitches. Be careful! If you drop the iron it will go right through the fabric! No, it's a miracle, but I didn't do it!

Adding the leading edge perimeter tape to bottom side of the horizontal stab.

Fabic Covering Begins

2011-12-12T14:08:00.007-05:00

I have been saying "It's almost ready to cover" for the last year. Well covering has finally started. I am using Ceconite fabric products along with the "Ekobond" adhesive by Stewart Systems. This is the same stuff I tested on the sample panel almost a year back. I really like the ease of application compared to the traditional 'Poly-Tac" adhesive from Poly-Fiber. I have covered the horizontal and vertical stabilizers to the point of being ready for rib stitching and finish tapes.

Rather than go into much detail, I recommend that you visit the following videos on YouTube. These are videos posted by Stewart Systems showing the covering of a similar control surface. If the YouTube links are broken, you can find the same videos on the Stewart Systems site: http://www.stewartsystems.aero

www.youtube.com/watch?v=rl9I3FOA6Bc
www.youtube.com/watch?v=48OeYmvYHDM&feature=related
www.youtube.com/watch?v=KCmzyct6J-0&feature=related

Here goes nothing!

Bottom side covered. You can see the anti-chafe tapes on the ribs.

Finished with the basic wrap.

Repeat the process for the vertical stab.

I plan to cover the rudder and elevator before I rib-stitch and apply the finish tapes.

Elevator Travel Stops

2011-12-07T13:32:00.005-05:00

When the elevator travel stops are installed the tail feathers will be ready to cover. The horizontal stab/elevator assembly was clamped to the welding table and leveled. A digital level was used to measure the angle of deflection.

I decided that the travel stops could be simple shims of the appropriate thickness to fill the gap between the elevator horn and the main spar tube of the horizontal stab when the elevator was at it's travel limit. The shim thickness was determined by inserting feeler gauges when the elevator was deflected the prescribed 24 degrees up and down.

The down stop needed a .160" shim and the up stop needed a shim .068". A collar was lathe turned to have a 3/4" ID with a .160" wall thickness. A sanding belt was used to reduce a portion of the wall thickness down to .068" thickness at the point of contact with the elevator horn. Half was cut away leaving a one piece shim to accomplish the up and down stop function.

This shows the shim in position from the top side.

This shows the shim from the bottom side with the elevator horn against the stop at 24 degrees deflection. .

After welding.

Close enough!

Simplicity Prevails

2011-11-16T16:02:00.008-05:00

I would really like to have the 4 into 1 exhaust on the Skyote but it is just too bulky and heavy for the little Skyote. I managed to fit it all in but it would be difficult to get the cowl off plus the primary pipes were quite close to several important parts of the air frame. Did I mention that it was heavy? So I reverted to a system which is very similar to the set-up used on the O-200 powered Legend Cub. It is simple and sounds pretty good as well.

The finished pipes will be similar to this except the exhaust pipe will be more vertical and near the center. Also, no cabin heat muff.

4 Into 1 Exhaust System

2011-11-05T19:31:00.012-04:00

I purchased an exhaust mock-up kit from Aircraft Exhaust, Inc. It includes exhaust stack stubs, a 4 into 1 collector and instructions. I got the PVC pipe and fittings from Lowe's.

The PVC tubing and fittings are somewhat larger in diameter than the stainless tubing which will make up the actual exhaust system. This gives a little extra clearance in tight fitting areas.

All of the primary tubes should be of equal length.

The left front cylinder (#4, blue tape) is the furtherest from the collector so it sets the minimum primary tube length. All of the others have to include extra bends to achieve the same length.

It is important to leave sufficient clearance around the tubes to allow for engine shake and to prevent unwanted heat transfer. Radiation heat shields may be necessary in a few places.

Although I intend to use a battery/starter-only system, with no alternator, I still want to leave space for the alternator if I ever change my mind. Here the alternator is installed to check for clearance. This added a little complication to the challenge. I think I am getting pretty close to satisfying all of the requirements. I still need to work out a short (6" to 8" long) tail pipe and plan the mounting tabs and brackets. Aircraft Exhaust will recommend where the joints will need to be added to avoid cracking.

All of this took about 2-1/2 days and lots of PVC pipe!

Final Paint Choice

2011-10-22T10:20:00.009-04:00

With fabric covering soon to commence, I have been forced to make a final choice on color and design for the paint scheme. I stumbled across an image of the beautiful Pitcairn PA-7S on the EAA site. I think the black and yellow scheme suits the Skyote well. The Marchadier and Bridges planes already sport the Pitcairn logo so I am just following along in their footsteps.

I decided to deviate from the PA-7 scheme by leaving the vertical stabilizer black rather than yellow. I think it makes the airplane look a little longer and also makes a good presentation for the Skyote logo. I'm thinking that the Pitcarin logo should be in metallic gold rather than yellow. Plenty of time left to make that choice.

The O-200 Is Here

2011-10-20T20:06:00.009-04:00

The new Continental O-200 came today. I have included some shots of the engine still in its shipping crate an well as some after it has been hung on the engine mount. Looks like it is going to work out just fine. I was relieved to find that the engine mount lined up very nicely. The biggest challenge will be designing the exhaust system. I hope to have a 4-into-1 system with the collector exiting out the bottom of the cowl just in front of the firewall.

O-200 Engine Mount

2011-08-29T16:03:00.013-04:00

The new engine mount for the Continental O-200 is fitted and tacked ready for final welding. Based on Hawkeye's aft C.G. condition and comparison to the weight and geometry of the Jab 3300, I decided to move the O-200 forward by 2" from the position specified in the plans. The plans call for 10" between the firewall and the back of the engine mount but this mount is 12".

At the risk of over doing a simple subject, I have put together a full sequence of fitting a tube to two parallel intersecting tubes using the "tube miter" software to print patterns. www.ozhpv.org.au/shed/tubemiter.htm

We are mating a 3/4" tube with a 1/2" tube. The tube miter program assumes that the 1/2" tube will pierce the 3/4" tube. This means that about 1/2 of the printed pattern will need to be discarded. Note that the tube miter program works in mm dimensions.

This is the part we need.

I use 3/8" flat stock to find the center line of the 3/4" tubes. Clamp the tube to the bench and mark each end on opposite sides. This will be used to align the patterns on each end.

Determine the length of the tube. This requires a little estimating using a tape measure and "eyeballing" the portion where the tape won't fit in. Align the pattern with the center lines on the tube and tape it in place.

Rough cut the tube on the band saw.

Grind the tube to match the pattern and check the fit. Because we are fitting a 3/4" tube to a 1/2" tube, the shaped end of the larger tube will need to be squeezed down for a better fit to the smaller tube.

I was very pleased that I managed to cut and fit all of the tubes for this mount without scrapping a single tube!

New Engine Choice

2011-08-16T20:56:00.004-04:00

The short version is: I have sold the Jabiru 3300 engine and ordered a custom built O-200 to replace it!

The long version is after reviewing the cooling problems others are having with the 3300 Jab and considering my options, I decided that it is best to make the change now rather than fight it for a long time and then possibly still have to make the change. I have already sold the Jab/prop/TBI and ordered a "slicked-up" O-200 from Don Swords of Griffin, GA. More about this engine later.

Refitting for the O-200 should go quickly as the plans provide all of the details for the installation. I think that most of the cowl can be salvaged but I have already started on the new engine mount.

In retrospect, all of the extra work required to adopt the Jab has set me back about a year from where I would be if I had originally gone with the O-200. Live and learn!

Weight and Balance

2011-07-07T11:01:00.018-04:00

I weighed the Skyote yesterday sans paint and covering. The empty weight (with engine oil) is currently 579 pounds. Assuming that paint and covering will weigh 60 pounds, I project a finished empty weight of 638 pounds with an empty plane C.G. of 15.5". According to the info supplied by Pete Bartoe, N27PB weighs 641 pounds empty with a C.G. of 12.3 inches.

I did the calculations for "normal" and extreme forward and extreme aft loadings. I distributed the projected 60 pounds additional for paint and fabric by area and location relative to the datum. The following table shows the results. (Click to enlarge.)

Here is a graph of the same data.

Note that the extreme forward condition is with a 100# pilot, no baggage and 100# fuel. The extreme aft position is with a 225# pilot, 20# baggage and 13# fuel, both of which are unrealistically extreme.

I am very pleased that the projected normal loading is right in the middle of the range at 19.5" while the extreme conditions are also still in the allowable range. It looks like NX88NX will be very forgiving of variations in loading.

Aileron Slave Push Rods

2011-06-10T16:19:00.006-04:00

I have been putting off making the Aileron interplane push rods for too long. I turned 8 plugs from 4130 and drilled and tapped them to 1/4-28 while they were in the lathe.

The tubes were cut to length and "bird-mouthed" for welding on each end.

Ready for tack welding and assembly check before welding.

Center Section Handle

2011-01-27T16:58:00.007-05:00

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.

Fabric/Painting Test Panel

2011-01-10T10:32:00.023-05:00

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.
http://www.polyfiber.com/

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.

Wheel alignment completed.

2011-01-07T14:14:00.002-05:00

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.

Toe-in Correction Contd.

2011-01-05T18:11:00.004-05:00

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.

Landing Gear Progress

2011-01-04T16:34:00.006-05:00

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.
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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.

Landing Gear Mod for Toe Adjustment

2010-12-30T16:03:00.006-05:00

The photo above shows the unmodified axle along with the flanged adapter and the Grove axle.

The outboard section of the axle was sawed off flush with the existing brake torque plate and ground flush.

I hope to get the gear back on the plane this weekend and begin the alignment process.

Landing Gear Toe-in Correction

2010-12-17T20:35:00.002-05:00

From the beginning we considered using Grove "bolt-on" axles so that toe and camber could easily be adjusted. Hawkeye has explained the rational for this mod in some of his previous postings. In the end, we decided to take a shot at using the straight tubular steel axles per Pete's plans knowing that we could always cut off the unwanted portion of the axle and add a flange for the bolt-on type axle.

In spite of our best efforts, we wound up with a few degrees of dreaded toe-in on both my and Glenn Bridges Skyoties. Glenn reports that his is a handful on pavement so it looks like a fix is in order. We had originally planned to just weld on the new flange after cutting off the old axle. Robbie Grove of Grove cautioned that the flange needs to be nice and flat to provide a good seat for the bolt on axle. With this in mind, we decided to use a bolt on flange adaptor. This allows the face of the adaptor flange to be machined flat after welding. The CAD rendering above shows how it all comes together.

The brake torque plate will bolt on the outboard face of the Grove axle flange so the Skyote landing gear track will increase a little.

The Grove axles are "in the mail" so I will post some pictures of the actual components soon.

David Teel Visits

2010-12-10T19:59:00.002-05:00

Good friend and renowned Skyote builder/test pilot, Davide Teel came by for a visit yesterday. David flew up from Eastman, GA. in his beautiful Waiex. David had to put toastie toes packs in his boots as the VW powered Waiex has no heater!

Wings Installed and Rigged

2010-12-10T09:12:00.004-05:00

Well it's been almost 6 months since I posted to this blog!There are about 50 reasons but no good excuse for such an extended lapse. Actually there has been a little progress during the past few months but no time for posting.

As you can see from the above photos, the wings are mounted and loosely rigged. The main objective here is to make sure everything fits. I also want to weigh the airplane sans covering and paint. I can estimate the weight and c.g. of the covering and paint and arrive at a reasonably close estimate of the final weight and balance. If I get a surprise and find that it is going to be less than ideal, it will be easier to make changes prior to covering.

I recently reworked the fuel system again which I will cover in the next post.

Safety Harness

2010-06-28T21:40:00.003-04:00

The safety harness is about 90% installed. The lap belts were anchored to the seat base tubes using a "wrap around" mount which eliminated the need for additional brackets. The lap belts will be close to the desired 45 degree angle.

The plans call for the shoulder belts to be mounted to the fuselage structure at the base of the turtle deck. I felt that this caused the belts to be angled sharply downward behind my shoulders which can cause spinal compression problems. I raised the shoulder belt penetration point to the top of the turtle deck. I will extend a cable attachment back to one of the fuse cross members near the tail. This will let the belts extend straight back from my shoulders and avoid the compression problem.

I bought the belts from Crowe Enterprises. Some of the RV guys are starting to use belts from Crowe. They make a very nice product and the price is much less than Hooker.

www.crowenterprises.com

Landing Gear Progress

2010-06-05T13:31:00.003-04:00

The urethane die springs in the above picture are performing well so far. That means that they are holding up the weight of the airplane and engine with no sag over time. There is no pre-load applied so far but as the wings, fuel and pilot add additional weight some preload will be necessary to maintain full ride height. The limited pre-load will give a softer "cushy" ride for the first 1 to 2 inches of gear deflection.

I intend to experiment with one additional combination of spring diameter and durometer. The current springs are 60A durometer and 2.5 inches in diameter. The next trial will be with 70A durometer and 1.75 inch diameter springs. If the smaller diameter works as well it will save about 2 pounds of unnecessary weight.

Mating the Wings

2010-05-24T20:35:00.009-04:00

Wow,it's been quite a while since I have made enough progress to warrant a new post! Hopefully I've got things back on track for a while. We managed to mate all four wings to the fuselage and center section over the past two days.

All of the holes were pilot drilled prior to assembly except for one of the fittings on each spar.

A series of drill guide bushings and special extended drills were used to match drill the mated parts to final size.

We made up this special extended drill so we could "line drill" the holes in the forward and aft spars.

Jabiru Engine First Run

2010-03-11T21:55:00.003-05:00

We started the Jabiru 3300 for the first time yesterday. It started on about the second blade but ran very rich. Normal adjustments had little effect so we rolled it back inside for a closer look. We discovered a metal flake stuck in the needle and seat of the Rotec TBI fuel regulator. By the time we got it back together the rain had set in. Rain is predicted for the next few days so it might be a while before we get to run it again. Sure did sound sweet as it leaned out when we shut off the fuel.

Tail Wheel Progress

2010-02-24T09:48:00.003-05:00

We shortened and de-arched the tail wheel spring. It was a little too soft in its original length. The spring is a Piper Cub unit 1-1/4" wide. It now feels good when fully loaded and has a good angle on the vertical pivot.

Tail Wheel

2010-02-04T17:38:00.003-05:00

The tailwheel was mounted for the first time yesterday. This is the Home Builder's Special from Aircraft Spruce. The wheel is 6" diameter. Only one spring leaf is installed at the moment. At least one additional leaf will be required. There is still hope for a carbon fiber spring for additional weight reduction. Given the light weight of the Jabiru engine, I am trying to keep weight off the tail as much as possible.

Instrument panel Progress

2010-01-25T20:32:00.009-05:00

Tom has almost completed the wiring for the instrument panel. The layout has evolved somewhat so that a few critical circuit breakers are located on the panel and a few non-critical breakers are located on a sub-panel hidden behind the AV80R GPS/Moving map. The AV80R has buttons located on its edges so it has to be surface mounted on the face of the panel. It snaps out easily for use in the "land mode".

"Eyeball" fittings are used for the signal wire penetrations through the firewall. Having the right tools really comes in handy for tasks like sizing the holes in the two-piece eyeball to the appropriate size for the wire bundle. Les set these up in his mill and sized the holes as required.

Fuel Piping FWF

2010-01-25T20:15:00.008-05:00

We completed the firewall-forward part of the fuel piping today. A Facet fuel pump is employed as a back-up to the engine driven pump and as a boost pump for priming at start-up. 3/8" tubing and hose is used throughout. A fuel flow transducer will supply info to the EIS engine monitor yielding fuel used, fuel remaining and time remaining. Others who have used this system have reported that it is very accurate.

The system is somewhat complicated by the addition of check valves to create separate and parallel systems for the two fuel pumps. This is probably overkill as the engine will likely run okay with gravity flow under most conditions.

Oil Cooler

2010-01-20T20:25:00.006-05:00

The Jabiru uses an oil cooler adapter which fits between the engine block and the oil filter at the front of the engine. The supply and return lines run to the oil cooler which is located back on the firewall. The adapter normally has 1/8"NPT ports but we enlarged them to 1/4"NPT feeding 3/8" hoses.

Cooling air will be supplied by a NACA scoop and flow downward through the cooler. The hot air leaving the cooler will be ducted down to the intake and used for carb heat when necessary.

Trim Tab

2009-11-15T07:53:00.004-05:00

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.

Comm Antenna

2009-10-18T20:49:00.003-04:00

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.

www.miracleantenna.com/airwhip

Possible Paint Scheme

2009-10-10T18:34:00.009-04:00

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!

Head Rest

2009-10-01T17:21:00.007-04:00

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

2009-10-01T16:42:00.006-04:00

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!

Throttle Quadrant Refinements

2009-09-13T13:40:00.008-04:00

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.

Throttle/Mixture Quadrant Completed

2009-08-30T19:33:00.008-04:00

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.

Cowling Progress

2009-08-22T20:16:00.007-04:00

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

2009-08-22T19:53:00.007-04:00

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.

Nose Bowl--One More Try

2009-06-23T20:14:00.003-04:00

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

Engine Cowling/Nose Bowl

2009-06-21T07:38:00.003-04:00

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

Hanging the Engine

2009-06-04T14:02:00.004-04:00

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

2009-06-04T13:22:00.002-04:00

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.

Boot Cowl

2009-04-04T20:06:00.004-04:00

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

2009-04-04T19:50:00.004-04:00

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

Throttle Quadrant

2009-03-16T13:58:00.010-04:00

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.

Turtle Deck Progress

2009-03-06T19:15:00.005-05:00

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.

Pete's Original Nose Bowl Tooling

2009-02-13T19:57:00.003-05:00

This is Pete's original forming block used to form the nose bowl on his personal airplane. Glenn Bridges talked Pete into letting us borrow the tool to form our nose bowls.

Pete included this test part when he sent the tool.

Checking the fit of the spinner backplate with the formed nose bowl. Looks like a good fit.

Time to start making airplane noises!

Interplane Struts Riveted

2009-02-13T19:40:00.006-05:00

The interplane struts are riveted. Still have to trim the angles on the ends to clear the brace wires.

Interplane Struts and Drill Fixture

2009-01-13T17:33:00.003-05:00

It's time to tackle the interplane struts. This will be another deviation from the plans since we will be using aluminum streamline tubing rather than the squeezed round tubing specified in the plans. The tubing is 6061 and has the same overall dimensions called for in the plans. The streamline shape requires that the aluminum spacer blocks be shaped to compensate for the teardrop shape. We designed and made a precision jig to hold all of the parts for drilling. The tubes were cut to length using a milling machine to achieve the final overall length. The jig is aligned with each end of the tube for match drilling the components.

Panel Layout Update

2009-01-02T19:31:00.005-05:00

Installing a foam mock-up of the floor mounted console showed that location to be less than satisfactory. After taking careful measurements, we were surprised to find that there was room to include the Comm and Transponder in the lower center of the main panel. I had assumed that there would be a conflict with the top of the stick but this is not a problem. This may be the final version.

Engine/Cowling Model

2008-12-27T12:03:00.007-05:00

I refined the engine/cowling model a little. I still need to add the cooling ram air ducts and some simulation of the 6 into 2 exhaust system. Pete Bartoe is lending us the forming blocks he used to form his nose bowl. The orange part is the battery which needs to go up front to help with the CG. The battery will be supported by a subframe off the engine mount. It looks like most of the exhaust and ram air ducts will be outside the cowling.

Saw and Sand Time

2008-12-24T11:22:00.004-05:00

Time to make a few parts by the traditional saw and sand method.

Templates for the Tip Bow Straps.

Floorboards

Seat Bottom

I used 3M adhesive to glue the templates over the protective plastic on the aluminum sheet stock. Just peel the plastic off when you are finished with no messy adhesive clean-up.

Avionics Console

2008-12-12T21:31:00.012-05:00

(Ed. note: This idea was discarded in favor of panel mounted units. See post of Jan 2nd.)
This is a CAD model of the avionics console which will house the MicroAir comm. and transponder units. It will be located on the floor between my feet. It will also contain the headphone jacks and the avionics master switch. I will likely need some holes or slots for ventilation.

The second model has the cover removed. The MicroAir comm. and transponder are not actually the same size. I just made up a composite model using the larger of the HxWxL dimensions from the respective units.

This is the flat pattern blank for the face/base plate for the console. Looks like a good prospect for waterjet! Would be much easier to bend up if it were made in two pieces and riveted together

Paint Update

2008-12-10T17:35:00.005-05:00

The primer I used initally didn't stand up to the MEK test so I switched to PPG brand DP40-LF. It works well and has good resistance to MEK after it cures a week or so.

I dropped my 30 year old POC touch-up gun and broke it so I was forced to treat myself to a new primer gun. I find myself priming many batches of small parts so I needed a small capacity gun suitable for priming. I bought this little gravity feed gun from Lowe's for $39.95 less a $10.00 off coupon. It works just fine for primer and gets about three times the milage from the paint as the old siphon gun did.

Instrument Panel

2008-12-08T09:02:00.009-05:00

It's about time to cut the instrument panel so I now have an excuse to waste endless hours contemplating the panel layout. My first objective is to keep it simple. The King AV80R satisfies this requirement as it can be surface mounted on the panel and only requires a 12 volt power plug to operate. The Grand Rapids EIS 6000 is desirable to help tune and manage the EGT/CHT temps for the Jabiru 3300.

The 3-1/8" instruments will be altimeter and air speed while the small instruments include G-meter, turn & bank, and compass.

The MicroAir comm and transponder will go in a small console on the floor between my legs.

Match Drilling Spar Fittings

2008-12-08T08:44:00.003-05:00

Match drilling Spar fittings with the fitttings installed on the spars can be akward leading to inaccurate drillng. We assembled the fittings to a small piece of spar and used a jig to hold it at the 7.2 degree angle. This allowed the fittings to be matched drilled and reamed in the drill press for better accuracy.

Wire Mesh Paint Table

2008-11-07T15:49:00.003-05:00

This paint table works very well. I tacked up a 10'x2' frame from 2x4's and covered it with 1/2" mesh hardware cloth. It works much better than painting on a flat table top because the air from the spray gun does not reflect back. This eliminates the tendency for parts to be moved by the blast from the gun. It also improves the paint coverage as the paint tends to wrap around the bottom edge of the part.

AircraftPaintSchemes.com

2008-11-04T17:59:00.008-05:00

I am working with AircraftPaintSchemes.com so we can have "paint templates" for the Skyote. I sent them three view drawings of the Skyote for conversion to their template format. They emailed the side view template today and promised the top view next week. The above are "quickie" examples . I highly recommed that anyone who is interested go to www.aircraftpaintschemes.com and down load the free software and instructions. Examples are provided for practice and understanding the software.
Hopefully the Skyote templates will be available by sometime next week.

Spar Party # 3

2008-10-09T22:59:00.009-04:00

Greg Swanson now has a complete set of drilled spars for his Skyote. Greg drove over in early October and with Tom's help we managed another 4-1/2 hour spar drilling session. This is the third complete sets of spars to be drilled using these jigs. That big smile is because Gregg is drilling the last of eight spars for his Skyote!

Marking all of the components before disassembling and packing for the return trip.

Alabama bound!

Great Picture

2008-10-09T18:41:00.006-04:00

David Teel sent me these pictures of the wings he and Glenn have built for Glenn's Skyote. A real work of art. If you check previous posts in this blog you will see that the spars for these wings were just drilled August 15, 2008. A tip of the cap to Glenn and David for such beautiful and speedy work!

Engine Mounted on Stand

2008-10-09T17:11:00.004-04:00

I decided to make up two engine mounts. The "prototype" above is made from scrap tubing and tack welded by me. I also cut out a profile of the firewall using MDF and mounted it with the engine. I will use this rig to locate all of the firewall forward components and to design the cowling. I still have to locate the diagonal brace between the left and right sides of the mount.

The second set of tubes will be welded by Dale after we are sure that everything is set with the prototype mount.

Engine Mount

2008-09-27T09:16:00.009-04:00

Started work on the Engine mount this week. I had originally planned to let Jabiru USA design and make the engine mount but after 3 months and no mount, I decided to do it myself. The photo above shows the initial tube fitting fixture. These tubes were profiled using a little piece of free sofware called "Tubemiter". You can Google it or you can go here: www.ozhpv.org.au/shed/tubemiter.htm

The program only works for the intersection of 2 tubes. You just input the diameters of both tubes, wall thickness and angle of intersection. The program then provides a flat pattern which you print and wrap around the tube as a notching guide.

This is a poor man's version of CAD for tube mitering but it works very well. You are still responsible for determining tube length and correctly indexing the notches on each end of the tube.

Aileron Nose Skins

2008-09-24T20:44:00.006-04:00

This is our first crack at forming the aileron nose skins. So far, this has been very difficult and we have not made a satisfactory skin. The amount of bend achievable with the above rig is not sufficient, leaving too much "fight" in the skin.

Update: Dale Doane was able to finish the bend of the nose skins using a set of slip rolls.

More Tank Progress

2008-09-17T21:28:00.004-04:00

The Header and Reserve tanks strapped in the approximate correct position. We are trying to figure out the best option to fill the reserve tank. It could be filled through the header tank with a valve between or it could have its own independent filler with no connection between the tanks.

Center Section Progress

2008-09-16T17:19:00.006-04:00

We have resumed work on the center section. Tom had completed the frame work last Fall but we had put it aside to work on other things. The 0.050" bottom shear plate has been fitted in the above photo.

We used a stretcher to curve the shear plate stiffener angles.

Yours truly drilling the top skin. This skin is secured by screws/nutplates. The leading edge skin is next.

Reserve Tank Model

2008-09-16T17:11:00.002-04:00

This is a foam model of the reserve tank which will fit above the rudder/brake pedals and below the original header/fuselage tank. The capacity is 6 gallons. We put it in the airplane last Sat. and it fits well. (Forgot the camera) More pictures soon.

Blakesburg 2008

2008-09-02T08:38:00.010-04:00

I made my first visit to the Blakesburg, IA fly-in this year. Blakesburg is a truly unique experience. No asphalt, no concrete, no commercialism. Just 350 or so superb antique aircraft parked in the grass with quite a bit of fly-by activity as an added bonus.

We had a nice gathering of Skyote owner/builders. From left to right: Hawkeye Hughes, Greg Swanson, John Roberts, David Teel, Glenn Bridges, Mike Kukulski, Dick Smith, and Dave Novak. Hats off to Dave for flying his beautiful Skyote in from Wisconsin.

That's Doc Packard in the center. Dick Smith on the left and Glenn Bridges on the right.
Doc was not present when we made the group photo. He bought his Skyote at age 67 and says he rolled it more than 4000 times before age made him give it up! Doc said he rolled the Skyote every time he flew it. That should be an inspiration to us all.

The tall guy is George Becker from Boulder, CO. George worked for Pete Bartoe at Ball Aerospace and made many of the parts for the original six airframes. George had some good comments on Mr. Bartoe and the Skyote.

This is Dave Fisher. Dave was the original owner of Hawkeye's airplane.

I really enjoyed meeting and talking to all of these people. As one might suspect, Skyote builder/owners are very interesting characters!

Spar Party

2008-08-15T19:06:00.011-04:00

Glenn Bridges and David Teel spent the day using our laser cut spar drill jigs to drill up all of the spars for Glenn's Skyote #89. Tom and I had pretty well perfected the process while drilling the spars for Skyote #88 so things went very smoothly today. We were able to drill all of the holes in all eight wing spars in about 4.5 hours of actual working time. The laser cut sprar jigs have been a great help in completing the spars quickly and accurately.

All drilled up and ready to go home!

Control Horns and Bell Cranks

2008-08-09T19:04:00.004-04:00

The control horns and bell cranks have been primed and riveted ready for installation.

Tail Feathers Complete (99%)

2008-08-09T18:56:00.004-04:00

The tail feathers are about 99% complete. The VR3 kit had no problems and Dale did his normal super job on the welding.

The Firewall Fits!

2008-07-25T22:04:00.004-04:00

We had a chance to check out the stainless steel firewall today with good results. The part was cut by waterjet complete with 75 rivet holes for the perimeter angle and the main engine mount holes.

Tail Feathers Progress

2008-07-25T21:57:00.004-04:00

The horizontal Stab and the elevators are almost done. The tail section is much easier than the fuselage or landing gear as the geometry is relatively straight forward. The VR3 tail kit has worked out well so far.

Tail Feathers First Look

2008-07-15T12:48:00.003-04:00

This is the first look at the VR3 kit for the tail feathers. This section of the airplane will be relatively straight forward compared to the previous sections as the geometry is essentially flat with no obscure angles. As usual, the VR3 parts fit perfectly so far. The only tricky part is squishing the ends of the large diameter tubes to mate up with the smaller tubes so that the "squish" all winds up on one side of the large tube. More on this later.

The tail kit contains 93 pieces and sells for $1232 plus $150 shipping and handling. All of the tubes are pre-bent so the shipping carton for the tail is pretty big.

6 Gallon Reserve Tank !

2008-07-12T21:29:00.007-04:00

Today we located the new design rudder /brake pedals in the fuselage. With me sitting in the fuse (6'-1" long legs) we were able measure for a reserve header tank to be located above the rudder/brake pedal assembly. That's Dale Doane holding the pedal assembly and "Chief Machinist" Les Kanna looking on. Looks like I need to go on the "Skyote Weight Loss Program" as there is more excess weight on my butt than I could ever trim off the Skyote.

Because the new assembly is only 8 1/2" tall there is quite a bit of space available between the top of the rudder/brake pedal assembly and the bottom of the regular header tank. The attached CAD image is a rough but conservative estimate of the tank that can be fitted with out intrusion on the knees or pedals. It has a volume of 1437 cubic inches which is 6+ gallons. This is a huge addition which will extend the range of Skyote #88 by more than 1 hour. The fat end (firewall) is 5.5" x 15" while the thin end (instrument panel) is 3.5" x 19" with a fore and aft dimension of 20"

The new pedal assembly looks like it will also yield additional leg room. The actual amount is yet to be determined but it looks like it will be more than 1" greater than stock and maybe 2" greater.

Rudder/Brake Pedals

2008-07-09T16:18:00.007-04:00

This the first set of rudder/brake pedals built to the Skyote/Van's hybrid design that I proposed earlier. Just tack welded at this time. This is a view of the left pedal from the aft (pilots) side.

The modified design has the potential of creating more leg room with its aft mounted master cylinders.

There is also the potential for a reserve header tank above the pedal assembly due to the shorter vertical dimension of this design. Looks like maybe 2 to 3 gallons can be squeezed in above the pedals.

Both the overhead pivot and the pivot at the base of the pedals have non lubricated nylon bushings. I chose Grove master cylinders and they look good so far. This design has fewer parts than the original Skyote design. Moving the master cylinder from behind the pedals eliminates the need for the bell crank assembly which frees up space for the new pedal assembly to move forward. This arrangement is commonly used on Van's RV airplanes and works quite well. I think the new design has combined the best of both approaches.

Spar Drilling Sequence

2008-07-03T20:48:00.016-04:00

The following is a step by step account of the procedure Tom and I used to drill the Skyote spars.
We chose to use laser cut drill guides to aid in quickly and accurately drilling the wing spars. The drill guide is essentially a replica of the spar web but laser cut from 0.125" CRS. The spar web and the spar angles or "caps" are assembled between two drill guide plates and matched drilled. Every single hole that will eventually be in the spar is drilled at this time. The entire operation takes about 35 minutes and completely eliminates the laying out of hole centers before drilling. It does require a very thorough understanding of the wing geometry in order to correctly model the spar in CAD. You will also want to carefully check and recheck your drill guides for errors before you scrap a lot of expensive spar parts! If you find a mistake in your drill guides it is easy to weld up the offending holes and manually drill them in the correct position. Ask me how I know! It is also important to thoroughly de-burr and smooth the drill guide plates as the laser leaves lots of sharp edges which can scratch the spar components.

The first step involves positioning the spar web between the appropriate drill guide plates and drilling tooling holes to accurately hold the spar web and angles in position for the subsequent steps. We use tooling holes spaced about 12 inches apart. The tooling holes are drilled into the hardwood spine on the table so that clecoes inserted into the tooling holes also hold the components to the bench.

This also a good time to mark the tip of the spar web for trimming for the taper.

After the tooling holes are drilled the guide plates are separated and and then re stacked with the spar cap spacers in place.
The above photo shows the bottom guide plate with spacers in place. The spacers will maintain the correct dimension between the flanges of the spar caps. The wire pins hold the spacers in position while all of the components are assembled. Next comes the spar web.

Then the next set of spacers.

Then the upper Drill guide plate.

Now a few of the pins are removed and replaced with clecoes to secure all of the components so that the spar angles can be inserted.

After all of the spar angles are in place and all of the pins are replaced with clecoes it's time to begin drilling. We used blocks and a clamp at each tooling station to be certain that the legs of the spar angles were seated against the spacers. We also used hardened drill guide bushings o assure that the drill bit was properly aligned for drilling.

We also used drill guide bushings for the larger holes.

Then drill,drill,drill,drill............drill!
Following completion of all drilling (about 35 minutes) we marked the inboard ends of the spar angles for trimming at the appropriate angles.

After drilling the spar components are ready for deburring. In this photo they have been clecoed back together to keep all of the components together and separate from other spars.

Bending the Tip Bows

2008-06-07T20:19:00.005-04:00

Today was the day for bending tip bows. Pete recommends bending the bows around a 13" radius block which seems to be the right number. We cut a 13" radius block with a few degrees of draft on the cut to help snug the tube down on the table while bending. Add a scrap of 2x4 and a 3/8" lag bolt and you have all you need to do a nice job of bending the tubes.

Our bending block has about 180 degrees of arc which is not enough to bend the tube without repositioning. It requires about 255 degrees of bend at the 13" radius to equal the same length of tube when it springs back to the 18+" final shape.

In the photo above you can see that Tom has repositioned the tube to get additional bending. The slider block which is screwed to the 2x4 does not need to be real tight as a little play lets the block have better leverage against the tube while bending.

Fun Time.

2008-06-06T16:39:00.004-04:00

Last week Tom and I flew our RV8 from RocK Hill, SC to Newnan, GA and met Glenn Bridges who flew his RV4 over from "China Berry Ranch" near Dublin, GA. Dale Doane, who lives about 2 miles from the Newnan airport, came over and took us to his shop where we rolled out #88 on its gear. The pictures show the RV8 (blue) and the RV4 (yellow) at the Newnan airport. It's always nice to have an excuse to fly but when you get to fly to see your Skyote on the gear it's a real bonus. Seems like RV's are popular with Skyote builders.

More Wing Assembly Progress

2008-06-05T17:46:00.005-04:00

After Tom got everything well organized we managed to assemble the false ribs and leading edge spar this afternoon. The spar still needs to be trimmed to the proper length on both ends so it is just clecoed for now. I should point out that I am using a modified approach to the interplane strut attach fittings. I am using "mirror image" fittings on the back side of the spar to eliminate the need for drilling holes in the spar angles. You can find more on this in an earlier post. Check the "fittings" category.

Wing Assembly Progress

2008-06-04T17:30:00.006-04:00

Tom has been working away with the rivet squeezer and puller and we almost have a wing assembled. Tomorrow we hope to get the leading edge spar fitted and then move on to the tip bow. So far everything has gone together nicely with just a few small adjustments. The biggest challenge is getting the assembly procedure just right to avoid taking things apart too many times.

Fuselage on the Gear!

2008-05-30T21:57:00.012-04:00

Today was an exciting day as we rolled Skyote #88 out of the shop on its gear. Dale Doane has done a fantastic job of fitting and welding both the main fuselage structure and the landing gear. You can tell that Dale is proud of his good work.

The gear turned out far better than I had anticipated. The geometry came out just right and it matches the fuselage attach fittings perfectly. The VR3 Landing Gear Kit was a huge help but the landing gear is still the most difficult part of the project so far. Well, maybe figuring out the drawings might be the most difficult, with the landing gear number 2 in difficulty!

Here are a few random detail photos:

From left to right thats Dale Doane, me, Glenn Bridges. Glenn's fuselage is about two weeks behind mine and will be on the gear soon.

Painting Small Parts

2008-05-30T07:28:00.003-04:00

Painting small parts is always difficult. One trick is to use masking tape sticky side up to stabilize the parts. The tape will actually hold the parts in most any position so that all of the edges can be covered. After painting one side allow the paint to cure sufficiently to be "tape proof" then turn them over and do the back side,

VR3 landing Gear Tube Kit

2008-05-17T16:46:00.006-04:00

The VR3 landing gear tube kit has been jigged up and welded. Even with the assistance of the VR3 tube kit, getting the landing gear assembled and welded correctly has been the most difficult part of the project so far. Dale Doane came up with the assembly jig pictured here. The jig is referenced off the firewall and holds the two axle tubes in the correct position for when the gear is compressed to the normal ride height and the tail wheel one foot off the ground. At this condition the toe is zero and the camber is 2.5 degrees.

The tube cluster at the axle is relatively easy, especially with the VR3 tubes. The difficult part is the upper ends of the gear tubes where they interface with the fittings on the fuselage. Getting the correct shape at the upper ends while maintaining the correct dimensions and alignment is a challenge. This could all be simplified if a correctly welded landing gear assembly were used to perfect a "stand alone jig "that would hold the tubes in the correct alignment for welding and not involve using the fuselage in the process. Maybe I could convince Dale to offer completely welded landing gear kits !

Assembing First Wing

2008-05-13T19:25:00.005-04:00

Tom and I started "dry fitting" the first wing today. This is essentially a matched hole assembly task as all of the parts with the exception of the ribs have been "pre-drilled" by the water jet cutter. So far everything is going well. The plan is to get all of the parts and the assembly procedure perfected then make a run at the remaining three wings.

Weight and Balance Estimates

2008-04-20T21:24:00.006-04:00

Based on his experiences with NX8XX Hawkeye Hughes has suggested 19" t0 19.5" as a good normal flying weight CG for the Skyote. It is my goal to achieve that CG without adding dead weight or extending the nose past the position specified in the drawings for the O-235 installation. I have utilized the Excel worksheets posted in the "Files" section of the Yahoo site by Mike to see if it is possible to achieve the above objectives.

The above CAD images show how the battery can be located near the front of the engine to help move the CG forward without adding dead weight. Also, by utilizing a carbon fiber tail spring an even greater forward shift can be achieved while eliminating 2# of unnecessary weight.

I currently estimate that the airplane can have an empty weight of 583# and a normal flying weight CG of 19.15"

Aileron and Elevator Bell Cranks

2008-04-14T17:26:00.004-04:00

The bell crank bearings finally arrived after a 45 day back order delay. The aileron and elevator cranks are all final drilled and ready for paint before riveting.

After painting and riveting

Forming the Cabane Attach Finger Plates

2008-04-13T20:17:00.007-04:00

Dale Doane came up with a good way to partially form the finger plates which make up the attach point for the aft cabane struts. 3/4" steel shafting was used to weld up a model of the appropriate tubing cluster. Note that this is a 3-D model as the cluster is not in a single plane. After tack welding the cluster to the tooling it is placed under a thick rubber pad with a backing plate and compressed in a hydraulic press.

Landing Gear Bungee Replacement Concept

2008-04-12T19:27:00.014-04:00

Most airplanes that utilize landing gear bungees also have STC'd modifications available to eliminate them. Must be a message in there somewhere! With that in mind, I have been designing a modification which eliminates the bungees but avoids conventional springs as well. The design utilizes commercially available polyurethane die "springs". Preliminary tests indicate that 6 springs 1-3/4" tall will do the job. I have selected polyurethane springs of the appropriate diameter, length, and durometer to give the equivalent of 300#/in. spring rate.

Referring to the CAD image, the silver tube is the lower strut tube which attaches near the axle while the red tube is the upper strut tube which attaches to the gear strut/flying wire attach point. The green split clamp collar represents a method of adjusting the bottom spring perch position. It can be adjusted up or down on the lower strut to change the spring pre-load. The polyurethane die springs carry the load by being compressed between the green Clamp collar and the red flange .

Note that there is one urethane die spring above the flange on the red tube. This provides a cushion for when the strut is fully extended.

Others have done similar modifications using steel die springs. I anticipate that the urethane will offer beneficial dampening (damping ?) compared to the steel springs. Another potential advantage is elimination of the total collapse failure mode of the bungee. It will likely take more than one try to arrive at the correct combination of variables. The urethane springs are interesting in that the effective spring rate decreases with compression. I have ordered enough polyurethane springs to mock up a test strut. You can see them at http://www.polyprod.com/

Modified Rudder Pedals

2008-04-10T21:01:00.012-04:00

I have previously mentioned the possibility of incorporating RV rudder/brake pedals in the Skyote. I went so far as to buy a set of RV4 pedal weldments from Van's. What I like about Van's design is the location of the master cylinder on the pilot's side of the pedal assembly. Also the master cylinder is an integral part of the pedal assembly making for easy adjustment of the pedal assembly in the fore and aft direction.

After laying everything out in CAD, It appears that I can move the pedals forward maybe 1.5" using the modified design. The plan is to build the pedals per the modified design, then adjust them as far forward as practical at assembly.

If I make the vertical dimension the same as the pedals in my RV7A, (which work very well), then there appears to be sufficient space above the pedals for a 2+ gal. reserve fuel tank. The RV pedals are 8.5" tall while the Skyote pedals are 13" tall leaving 4.5" of space above the pedals. A 14"x14" by 3" deep tank would have 588 cubic inches or 2.5 gallons capacity. I won't decide on the reserve tank until the pedals are actually in the airframe.

In the end, I decided to make my own pedals, using some of the Skyote design, some of Van's geometry and some of my own. The CAD images show two options, one with plate type pedal and one with a pedal constructed from tubing. The Skyote drawings show similar options. The images are for a left pedal. In both variations I have used non-lubricated "plastic" bushings for the overhead pivot as well as the pivot at the base of the pedal. These bushing are readily available in many material variations. One easy source is http://www.mscdirect.com/.

I was originally enamored of the tube style brake pedals but have lately come around to liking the plate style pedals better.

Jabiru Engine Workshop

2008-03-22T20:50:00.006-04:00

On March 14, 15 and 16 I attended a Jabiru engine workshop at Jabiru USA in Shelbyville, TN. I enjoyed the experience and found it very helpful in planning the installation of the Jabiru 3300 in the Skyote.

Spar Attachment Mods

2008-03-12T19:41:00.018-04:00

I have a personal (maybe irrational) hang-up when it comes to drilling four 0.188" holes at close proximity in the horizontal legs of the spar angles for the attachment of the interplane strut fittings. I have decided to incorporate "mirror image" fittings to completely eliminate the need for holes in the spar caps. The CAD images illustrate how this would work for the main spar. The first three images are per plans. The last three images are of the modified approach.

I do not mean to imply that there is any problem with the original design. but is interesting to note that as designed, the interplane tension wire puts the spar flange in bending by pulling perpendicular to the spar cap.

The proposed modification will add about 5 oz. per wing or 20 oz. to the airplane. I will save more than this in paint weight by using silver for the wings. Since weight added out on the wing has a magnified effect on handling, it is important that the "saved weight" also be on the wings.

The Jabiru 3300 I plan to use is about 25 pounds lighter than the normal O-200 so I have a few pounds to play with. I am confident that the airplane will come in substantially below 600 #.

Control Stick components

2008-03-12T14:22:00.006-04:00

Most of the control stick components have been completed and ready for welding. The stick gimbal components were done in the traditional way, paper pattern, saw and sand. The aileron horns were done by waterjet.

I was not comfortable with trying to get the 3/4" hole through the longitudinal tube so I took it to my friends machine shop and he cut it using his milling milling machine and an end mill. I could see some serious potential for hanging and ripping something if I tried it with a drill bit in the drill press. It came out nice with no problem.

The 1-1/8" control stick is a real handful. I plan to replace it with a 1" diameter tube before welding. Of course that means remaking the pretty little pieces!

Fuselage out for final welding.

2008-03-07T21:11:00.006-05:00

On Monday the 2nd I took the fuselage to Dale Doane for final welding. The fuse rode well on the racks I built for the Tundra. The weather was great so there was no worry about the fuse getting wet. Dale started welding shortly after I got there and is moving right along. The photo shows the cluster at the bottom of the firewall where the forward landing gear attaches.

I tried to get some photos of his work but my camera was acting up. I will add some more photos after my next visit. I intend to leave the fuse with Dale until we get all of the attachments made and welded on.

Installing Motor Mount Bushings

2008-02-28T16:52:00.010-05:00

The following photos show the use of a fixture made to hold the motor mount bushings and washers in the correct position for welding. The appropriate hole pattern was carefully laid out and drilled in a piece of 3/4" MDF. It serves three purposes, first as a fixture for the motor mount bushings, second as a mount for the "rotisserie" forward pivot shaft, and third it will be used later to align the motor mount weldment when it is fabricated. This will assure a good match of the hole patterns if the welding distortion is not too great.

The last two photos show a small mod we made to the motormount bushing attachmment. We used rectangular tubing with one side cut away to make 45 degree gussets to reinforce the attachment. Again, a few ounces of added weight but it is in the area where the Jab engine saves 25 plus pounds so a little give back here won't hurt.

Aligning Landing Gear & Wing Attach Parts

2008-02-22T11:57:00.016-05:00

The alignment of the landing gear and especially the wing attach fittings is critical. The plans call for 1.9 degrees of incidence for the lower wing and this is set by the position of the attach fittings relative to the lower longeron. The magic of CAD reveals the correct dimension of each of the four side plates which make up the two attach box fittings on each side. The fittings in the photos were cut by waterjet complete with the attachment bolt holes correctly offset in each part to achive the 1.9 degree incidence.

One method of ensuring the proper alignment uses threaded rod, tubing and spacers of the correct length to make an "assembly" which can be positioned correctly before welding. The following photos show the fitting assemblies for both the landing gear attach and lower wing attach components. The fuselage is upside-down in these photos.

Note that the wing attach fittings establish a 1.9 degree angle of incidence.

EAA SportAir Fabric Workshop

2008-02-19T21:03:00.004-05:00

Tom and I attended the SportAir fabric covering workshop in Lakeland over the past weekend. We were very pleased and impressed with the experience. Lynn Zaro, the workshop leader, was fantastic. Not only is she a world class fabric expert but also a great teacher. This was a very helpful workshop. We both came away with complete confidence that we can do a very good job covering the Skyote. Wish I could have left the TIG welding workshop with the same degree of confidence!

Wing & Gear Attach Fittings

2008-02-14T13:18:00.002-05:00

Made the first run of fittings with the new waterjet source today. Due to limited time available today we only cut the 0.080" wing and landing gear attach fittings. We will cut the remainder of the order next week when I return from the SportAir Fabric covering workshop in Lakeland, FL.

Everything went well. The quality of the work is excellent.

More Parts in CAD

2008-02-11T19:01:00.000-05:00

Today I managed to convert all of the more demanding fuselage attachments to CAD. This includes the wing attach boxes, the landing gear attach plates, motor mount plates, etc.. I also did the elevator and aileron bellcranks and horns. Hope to get them all cut by waterjet later this week.

New Waterjet Source

2008-02-11T18:36:00.000-05:00

I met with a possible new source for waterjet services this week. The owner is very interested in learning to fly as his wife and her father and brothers are all pilots and airplane owners. He was very interested in the homebuilt market as a possible outlet for his services. Better yet, he is excited about the possibility of building a Skyote for himself! He is totally agreeable to helping set up standard "batch files" (my terminology) for fitting kits and might be willing to serve as the source for fittings. The prices quoted are much better than my initial supplier. This could work out to be a very good arrangement for Skyote builders as well as other homebuilders. I will be taking metal and DXF files to have fuselage attachments cut later this week.

RV rudder Pedals for the Skyote?

2008-02-02T18:55:00.000-05:00

Some quick measurements reveal that Van's RV-8 rudder pedals will fit nicely in the Skyote. I don't plan to use the adjustable pedals although they would easily fit. The whole assembly works very well on our RV-8. Everything including brake cylinders is included in the package. Up to 1 1/2" can easily be removed from the width of the assembly. If this works out, it will be another time saver.

A half-set of pedals from the 7A would also work if you wanted to stay with the overhead pivot. However it looks like RV8 pedals would make a cleaner installation.

Or maybe best yet, RV4 rudder pedals!