Issue 73 Sonex Special

Page 1



On the cover: Eric and Jennifer Scheppers ( 3300cc Jabiru powered Sonex, heading home from the 2003 Golden West Fly In. Photos: Pat Panzera By John P Moyle Associate Editor Photos: Pat Panzera Eric Scheppers: Eric and Jennifer Scheppers’ Sonex won the trophy for “Best Plans Built Aircraft” at the 2002 Golden West EAA Fly In, at Marysville, CA. This bright red sport plane could not have been more deserving of that honor. When the Scheppers made the decision to begin building this plane, they had had previous experience Eric and Jennifer Scheppers begin the taxi toward home, at the 2002 Golden West Fly In. building and flying a Challenger II. They knew they wanted their next plane to THE ENGINE be of the side-by-side seating style, so the search began A 2180 c.c., 80hp Type One Volkswagen (based on the for the design which, for the next couple of years, would infamous “bug” engine) was planned to provide the motake most of their time and money for construction. tive force, but by the time they got close to needing the firewall forward parts, their financial circumstances had Like many, the unorthodox appearance of the Sonex improved to the point that they decided to upgrade to the prototype had the Scheppers’ skipping past the early 3300 c.c. Jabiru. The Jabiru is an air cooled, horizontaladvertisements, which declared it to be the “Sport Plane ly opposed, six cylinder engine, which is (along with the Reality Check”. But after eliminating most of the other VW) one of the powerplants approved for installation by available designs on the market for one reason or anoththe Sonex factory. It’s also one which they support with a er, they wound up returning to the unusual profile of the special engine mount and fiberglass cowl, specific to the Sonex. Delving further into the plane’s features, they engine/airframe. The Jabiru engine, as well as the approultimately discovered that this design did meet the highpriate wood prop for this combination (from either est percentage of the criteria they were seeking. In time, Sensenich or Prince), is also available directly from the their previous aversion to Sonex’s unusual top line shape Sonex factory. was overcome and now they have decided it’s actually rather attractive in it’s own right! Admittedly, the big Jabiru is a snug fit under the cowl, but it fits just fine indeed. Eric did some “fun-gineering” in the The original intent included building the plane completely engine compartment, where you’ll find he has recycled from plans, fabricating virtually every part themselves. and converted an empty can of Drano (drain cleaner) The only planned exception to this would be the welded into an air/oil separator! It still wears the Drano colors items, such as the engine mount, which includes the critiproudly, and it never fails to draw a comment or two cal main landing gear socket geometry and accepts the when the cowl is removed. titanium rod gear legs, RV style. All of the welded components, fiberglass details, and the formed acrylic canoThe cowl removal is primarily a matter of sliding a series py were obtained from the factory, but the Scheppers’ of piano hinge pins out. Either side can be removed indedid essentially manufacture the remainder of their own pendently of the other, gaining access to the critical in“kit” which they then assembled, trading their time for the spection and maintenance areas. A “Leatherman” pocket money saved. The “Easy Build Kit” which Sonex Ltd. multitool is the only tool required to get the cowl off and now offers, wasn’t available back then. They chose to on. Handy, since many pilots carry one of these on their not wait for it to hit the market, preferring instead to get belts anyway. On the day that we met Eric and Jennifer started right away once they decided to build this aircraft. for photos, Eric opted to remove only half the cowl.


A very tidy engine compartment indeed.

The Jabiru comes complete with cooling plenum.

Cabin heat and Carb heat are supplied from the same heat muff.

The supplied fiberglass cooling air plenum needs a bit of trimming to work with the cowl.

The Jabiru oil pan is cast aluminum and finned.

...and of course the Drano can!


This image was scanned from the original 24” x 36” plans, and reduced to fit this page.


Eric comments that the plans themselves are first rate, and the suggested materials layout was both practical and wasted little of the 6061 sheet aluminum, from which the primary structure is formed.


Once cutting the sheet stock into the required dimensional shapes for the various side and bottom panels, the rivet holes are laid out and drilled slightly undersize at first. Later, when the substructure of aluminum angle and the next overlapping panel are all aligned and clecoed together, the parts get drilled to the final diameter and deburred. Once all is fitted up, the clecos are permanently replaced with Cherry® brand stainless steel, blind rivets. Eric and Jennifer opted to use the air powered hydraulic rivet puller offered by Harbor Freight, to draw most of the structural rivets. A hand operated rivet tool was used on occasion, where the powered unit was difficult to use due to space or other ergonomic issues. Our intrepid builders acknowledge that you could build the entire airframe with just a hand operated device, but suggested that you’d have forearms like “Popeye” by the time you finished! There are thousands of rivets involved

in the construction of the Sonex, but if you’re determined to build where pneumatic power is unavailable, it’s possible to construct this entire project with hand rivet pullers. In tribute to the quality of the plans and their experience with the factory staff during the construction phase, Eric claims he’d build another one without reservation. He says that the only change he’d make would be to raise the windscreen bow for a better match with the canopy. The early builders discovered that it was possible to do this, and also raise the installed height of the formed acrylic canopy to achieve a bit more headroom, and a more pleasing flow to the top line profile.


This aircraft began life with a polished aluminum fuselage and wings, but before long, the issue of the overwhelmingly bright reflection of the sun off of the wings, causing near blindness at times and contributing to occasional sunburn problems for the planes occupants, led them to decide that a full paint job was what they needed. It’s now red. It’s really, really red. Completely and totally RED, no stripes, no accent colors. Just RED!! You can’t miss it!! The judges at the Golden West EAA Fly In 2002 certainly couldn’t help but notice this aircraft.



While Eric and Jennifer were building their plane, another builder, Jack Lockamy of Camarillo, CA, became a close friend and avid competitor in the race to completion. The Scheppers had met Jack while attending the Sonex Builders Workshop in September of 2000. Even though Jack was building from the early version of the Easy Build Kit, the two planes advanced in a neck-andneck fashion. They assisted one another and flew their maiden voyages only one week apart.

JACK LOCKAMY Jack Lockamy decided that the Sonex was probably the right plane for him, but wanted to attend the builders workshop and learn more about the company and the aircraft construction process before he committed to a large financial outlay. He took a friend along as his guest, who was impressed enough to buy plans set #277, just after the event wrapped up! For those who may not be aware, the Monnetts offer a builder’s workshop every quarter, at their Oshkosh WI. location. The Sonex workshop costs $200. (free for plan holders) If you decide to purchase plans after attending the workshop, you may subtract the fee from the plan cost. You are entitled to bring one guest or family member. Many builders have brought their building partners or other friends interested in their project.

The plans consist of a healthy roll of “D” size (24” x 36”) expertly drafted CAD drawings, and a “Builder’s manual” contained in a 1” 3 ring binder. Among other valuable pieces of information, the manual contains several pages of material planning. Pages such as what’s shown above, show the builder how to precisely lay out the sheet stock to optimize the best use, yielding very little waste..


Shortly after the workshop, Jack made his own commitment, and was issued plans #300, and had his “Easy Build” kit shipped by truck to his home in Camarillo, CA. Jack found his inventory to be correct and dove right in to the building process. Frequent telephone conversations with his new friend Eric Scheppers helped keep the motivation factor high, and the project on track. A friendly competition developed between these guys, which kept them both pressing on even when the doldrums set in, as so often will happen during a project of this scale.

The Scheppers stayed with the recommended “Day Jack’s plan was to VFR” panel, including build a large disthe Grand Rapids placement Type 4 technologies, Inc. EIS Volkswagen converengine function monision utilizing availator. There are no vacble components from uum instruments, nor Great Plains Aircraft a transponder inSupply. He had chostalled, and none sen this engine to needed as far as their save money, which style of flying is conafforded him the abilcerned. They fly in ity to buy the Easy pleasant weather, Eric and Jennifer’s panel is clean, simple and well laid out. Build Kit from Sonex. which at home in the Like most folks, he had budget constraints, and building central valley of California, there is plenty of. The Schephis own engine allowed him to stay within his own. Jack pers are just about the personification of what the factory also declares that the plans are terrific, maybe even the states as their target market; the fun flyers, those who best ever offered by any experimental aircraft designer. just want to go up and punch holes in the sky on a nice The 110 pages of CAD engineered prints are beautifully day, and maybe take an occasional modest cross counproduced, and from my experience, the least intimidating try flight..


plans I’ve seen. Editors note: As a professional CAD draftsman, I have to agree that the plans for the Sonex are first rate! ~Pat Jack’s Sonex building experiences are pretty similar to those of Eric Scheppers, except (as a fast build kit owner) he simply had a lot less of it to do! The problems encountered by one soon became the mutual focus of both, until it was resolved to their collective satisfaction. Some difficulties required questions be presented to Jeremy Monnett at the factory, which were quickly dealt with, usually via e-mail. Both Jack and Eric now include Jeremy as a good friend.

Photo courtesy Jack Lockamy

Jack’s Sonex.

Photo courtesy Jack Lockamy

Scheppers plane left, Lockamy’s plane right. The biggest difference between the two at this stage is the engine choice and the cowls that cover them. The Jabiru cowl on Eric and Jennifer’s plane is flat sided, where as Jack’s VW cowl has the rather conspicuous “cheeks”. THE TYPE IV ENGINE Jack Lockamy’s engine developed cylinder head trouble during his taxi test period, and while he was awaiting the arrival of a replacement head, Eric Scheppers made his first flight. A classic conclusion to a real close race! Jack was able to make his first flight only one week later.

In sad conclusion, the Lockamy Sonex led a brief life. When Jack’s Great Plains “Force One” prop hub let go during a routine departure, while Jack was still at pattern altitude, he had the choice of mature citrus orchards all around him or turning back to the field. His chances amongst the trees was certainly high risk, making an attempt to return to the airport behind him his best choice. Unfortunately, there simply wasn’t enough altitude to trade for distance, and the effort fell short. Jack was badly banged up (he has recovered almost 100% now) and the aircraft was nearly a complete loss. He did report that the new rotationally molded plastic fuel tank survived the wreck and spilled not a drop of its 16 gallons of avgas. That’s a mighty tough container!

Photo courtesy Jack Lockamy

Photo courtesy Jack Lockamy

Jack’s engine installation was first rate.

JOHN MONNETT Second engine run during break-in produced some BAD results! Here you see the right head (#4 cylinder) with a burned head gasket surface. Temperatures were fine at the time of melt-down. CHT: 275º F and EGT 1050º F. Jack believes the cylinder was not sealed properly against the head, thus causing a leak.

Sonex designer John Monnett has a considerable history in Experimental aviation. His early aircraft include the Sonerai series. These tube and fabric fuselage, aluminum wing planes were available in multiple configurations, low or mid wing, conventional or tri-gear. All were powered by the popular Volkswagen engine. Monnett was one of the founders of the Formula “V” Racing class,


got an enthusiastic response of the folks from across the Atlantic.


John Monnett has carried a definite focus throughout his design. Keep things simple. Where ever possible, he chose the least complex method available to achieve this goal of an easy to construct, personal sport plane, which could be built by pilots of modest means.

Photo courtesy Jack Lockamy

These are Type 4 stock 71mm crankshafts. The crank on the left has been machined by GPASC for the Force One Prop Hub. The crank on the right is un-touched and shown for a comparison.

John set out to power this design, the Sonex, with a modern adaptation on the Type One Volkswagen engine, delivering 80hp to the prop at 3400rpm. Other engines which are approved for installation include the 80hp 2200 cc Jabiru and the larger 120hp 3300cc version. Engine mounts for all three, in conventional or tricycle gear styles, as well as cowls matched for fit, are provided by Sonex. The current state of the Easy Build Kit is pretty amazing. The skins arrive precut to the exact plans dimensions, with the rivet holes and fuselage openings precision cut as well. Huge time savings are resulting from this new level of advanced prep work provided by the factory. The skins which require shaping are delivered in that condition, and parts which would need to be bent in a brake are provided that way as well. Every kit owner with whom I’ve spoken, gives high marks to the factory for the kit . Since it’s introduction, the Sonex has seen an evergrowing following, the builders workshops are always a “full house affair” and are highly recommended for those seeking a greater knowledge of monocoque aircraft construction. A history lesson about Volkswagen engines in aviation is included at no extra charge by the man who lived it!

Photo courtesy Jack Lockamy


GPASC Force One Prop Hub and large nose bearing for the Type 4. The case requires special cutting/ machining to allow for the over-sized #4 bearing.


17' 7"

Wing Span


and spent many a day competing against the likes of the late Steve Wittman, for whom the airport at Oshkosh is named.

Wing Area

98.0 sq. ft.

Air Foil

NACA 64A415

Primary Structure

6061 aluminum

John’s company was sold to INAV in the 1980’s, and vanished from the scene not long thereafter. Great Plains Aircraft Supply now owns the rights to market those designs. The Monnett family remained in the aircraft business, focusing on rebuilding services.

Cockpit Width

40 in. at shoulders 38 in. at hips

Stall Speed (25° flaps)

40 mph [64 km/h]

Stall Speed (clean)

46 mph

When John was approached by European aviation businessmen about designing an aircraft “like the Sonerai”, but with more traditional “side by side seating”, he didn’t believe that a redesigned Sonerai (or anything closely resembling this proposal) would have satisfactory performance. However, he had another type aircraft in mind that might fit the bill, so he laid it all down on paper and

Max Flap Extended (Vfe)

100 mph [161 km/h]

Maneuvering Speed (Va)

125 mph [201 km/h]

Never Exceed Speed (Vne)

197 mph [317 km/h] JP Moyle


By John P Moyle Associate Editor Photos: Pat Panzera When John Monnett began designing the Sonex he stayed true to his earliest roots in light aircraft. He has always been a champion of the "keep it simple" philosophy, and was determined to create a highly standardized aircraft that would fulfill the basic needs of the majority of builder / pilots, while not devastating their family nest egg. His study of the many aviators based around Wittman Field in Oshkosh, Wisconsin, revealed that the typical pilot (regardless of aircraft type) flies about an hour or two on the weekends, in the vicinity of his home field. He is likely to take his plane on an overnight trip two or three times in one year, and will plan a significant cross country once every couple of years. If these averages are even remotely accurate, there are an awful lot of airplane owners that are seriously over equipped for their mission. The "reality check" that Sonex claims in their ads is pretty obvious: If you are like the average aircraft owner, which is as stated above, and fly primarily in day VFR conditions, why are you spending multiple years and a sizable fortune, building an aircraft which so far exceeds your real needs?


standard size humans. You may have yours with either conventional (tail dragger) gear, or a tricycle undercarriage. The choice of dual (between the knees) control sticks, or a single center mounted stick, is another option for the builder. Rudder pedals are provided for both sides. There are no toe brakes, but

Eric Scheppers chose to go with the dual sticks. Brakes and rudder pedals are as per plans. rather a simple hand lever on the left side of the plane, which applies the stopping power equally to both main gear wheels. Differential braking is not offered. The taxi directions are accomplished through the direct steering tail wheel, or nose wheel. Reports from those currently flying claim the ground handling is on a par with the very best of light aircraft.

The Sonex is completely within the expected and much anticipated final rules for Sport Pilot / Light Sport Aircraft. The presumed restrictions of the as yet unconfirmed Sport Pilot rule are expected to allow single engine fixed gear aircraft of not more than two seats, with maximum speeds not to exceed 132 mph (cruise) and stall speeds around 40 mph. Permissible gross weight will probably be less than 1,235 lbs. One major advantage of the Sport Pilot rule will be the ability to satisfy the medical certification with a current state drivers license. If your class III medical may one day be at risk, this could be the design that keeps you involved in aviation without necessarily being made to jump through all the hoops that your AME might require of you.

The polycarbonate windscreen is a flat wrap affair which matches up to a blown acrylic canopy, which in turn mates cleanly to the aluminum turtle deck. From the top longeron down, it's all sheet aluminum and aluminum angle, with skins mostly laser cut to the exact size with precut holes and pilot drilled. The fuselage is entirely fastened with Cherry® brand stainless steel blind “pop” rivets. The only fiberglass components are the cowl, wheel pants, elevator tips and rudder tip.



This all-metal (structure) aircraft was conceived as an "Everyman's" design, while holding close to the concept that standardization breeds reduced costs, and similarity of experiences and results amongst the builders. The builders who complete each section, share their knowledge with the fellows not yet at that stage. The builders network eventually becomes the "go to" source for casual information, while the factory remains the ultimate authority, and stands ready to assist when needed. The Sonex is a side-by-side style two seater for FAA

The fuel tank is a super tough, rotationally molded, one piece unit, which holds 16+ gallons of either aviation fuel or mo-gas. It sits at the top of the forward fuselage, in front of the CG. This location allows the plane’s CG to move approximately 2.4”, from a full fuel condition, to the 1.5 gallon condition used in the example tables in the provided flight manual. This could be a problem if the plane was loaded to gross (with full fuel), at the aft CG limit before a flight. Burning fuel would cause the CG to move rearward, potentially to a condition where the CG is upwards of 2” aft of the aft CG. Read more on the CG


issues in the paragraph to follow. The fuel tank’s location provides a short gravity feed run to the carburetor, mounted almost directly below. There’s a hatch just

The fuel access hatch (shown open) exposes the fuel filler cap and neck. ahead of the windscreen, which opens to provide access to the fuel filler neck. Although this location is the epitome of simplicity, the proximity of the fuel filler to the polycarbonate windscreen causes some difficulty. Gasoline can attack the material and cause it to craze. Extreme amounts of care should be used to keep fuel off the windscreen. While some will say "only sixteen gallons?!?!", Here's another reality check. 16 gallons will get you a solid three hours of travel and more than four hundred miles, with reserve. Can you comfortably sit in a compact airplane for longer than that?? Will your bladder permit that kind of abuse?? A break at the three hour mark seems like the perfect plan to me!! Fuel tank safety is one of those issues that seem to always generate a vigorous debate amongst builder/pilots. Many aviators will steadfastly state that they won't fly in an aircraft with fuel in the fuselage, all fuel must be located in the wings!! It would be simple to just agree with the presumed logic of this argument on apparent safety grounds, but there is more to the story. In actuality, there is fuel "in the cockpit" in nearly every design, in the form of gas being pumped through fuel lines from the wing tanks to the engines distribution system. At some point these lines may be located right on the floor of the fuselage until

they reach the firewall. Since history has shown that aircraft which have accidents rarely strike the ground roof first, it's probably safe to say that off field landings, where the plane strikes the ground in more of a landing attitude, are more often the incident scenario than an out of control crash. Given that, it might also be fair to say that the part of the plane most likely to sustain damage is the bottom of the fuselage and the lower surface of the cowl and wings. If this is true, then is it in our best interest to expose the storage vessels for your only explosive component in the plane directly to the path of greatest destruction?? Where then is the safest place to carry your fuel load? The designers of the Sonex can make a very solid case for their choice of fuel tank location, above the top longeron, behind the firewall, in a really tough tank with a relatively modest volume. This may be the best answer to the question since it puts the flammables as far from ground contact as possible. The limited (16 gal) seamless tank is less of a hazard than double that amount, which is offered in many planes. The “rotationally molded” tank is very strong, and being a single unit, also contributes to the safety profile by not contributing to the pilot’s workload. No tank switching! Central location equates to little need to trim fore and aft, and no need to trim laterally at all. Simplicity adds to safety. The tank itself is pretty interesting. For those unfamiliar with this product type, let me describe the manufacturing process. A female mold is created which allows some fairly odd shapes, meaning that we can make use of all the available area in the fuel tank location. Introducing a known amount of plastic in powder, granular, or liquid form into the hollow, shell-like mold, the mold is heated and simultaneously rotated about two principal axis so that the plastic enclosed in the mold adheres to, and forms a layer against the mold surface. The two-axis mold rotation continues during the cooling phase so that the plastic retains the desired shape as it solidifies. When the plastic is sufficiently rigid, the mold rotation is stopped to allow the removal of the plastic product from the mold. The basic steps of: (a) mold charging (b) mold heating (c) mold cooling (d) part ejection See images below. (Continued on page 18)


were the days before the Internet brought all of us together in real time, where rumors get challenged or defended almost instantly By John P Moyle, Associate Editor Offered by Aero-Conversions, Inc. as a “U-Assemble“ kit, the 2180cc, 80hp AeroVee engine is the least expensive of the factory approved engines for installation in a Sonex aircraft. The list of other aircraft which can use this engine is quite long, and includes virtually every plane ever flown with a Volkswagen derivative as the power source.

Besides loyalists to one brand or another, or competing designers with differing points of view, it's hard to tell when you are being sold a bill of goods, or being offered the real deal. In the Volkswagen engine conversion business, there have been both saints and sinners. Some of the most notable failures came from nice folks with a decent product, but not necessarily the business acumen to survive in a tough market. There have also been outright charlatans who have promised much, but delivered little.



Based on the Type I (the infamous "VW Bug" engine), John Monnett was flying behind converted Volkswagen engines from the very beginning. Along with Steve Wittman, John built and raced Formula Vee pylon racers, and they had the time of their lives. The early racers evolved into some fun sport planes, (the Sonerai series as one example), all powered by "bug engines" of one sort or another.

The Aero-Conversions 2180cc long block.

When John Monnett and his family reentered the marketplace with the all new Sonex aircraft design, they also decided to attempt to produce a complete kit version of the most widely accepted VW based 2180 c.c. aircraft engine. John took a hard look at what worked, and what didn't, examined the real causes of some of the most often claimed shortcomings, and developed a concept that through years of research and development, has brought us to the modern AeroVee engine.

The complete engine Unfortunately, since kit currently being ofthe VW was easy to fered is strictly a “Uwork on in our cars, Build-It” affair. AeroVee many people bedoesn’t sell assembled lieved that they engines. If you are not could stick one on feeling confident about their micro mini AeroVee conversion kit, shown w/ optional stainless steel exhaust your ability to build and midget sport plane system. Great sounding straight stainless steel exhaust headers fly an engine assemdesigned for the Sonex application are available from Aerowith almost no modbled by yourself, there Conversions at a reasonable additional price. ifications, and magiis almost certainly cally it would besomeone in your EAA come an airplane engine. There was a great deal of trial chapter who can help you with this weekend project. The and error. These early creations lacked solid engineerassembly video is a first rate production which really ing, and frequently the failures weren’t openly discussed. shows you how to do it right. Watch the video a couple Rumors of some parts being deadly and others being the times before you enlist the assistance of all your budlatest and greatest were often wildly inaccurate. These dies. It’s a confidence builder!!


will allow the use of 100LL, or high octane auto fuel. The cylinder heads are from a long line of vastly superior aftermarket units, which have proven themselves in a wide range of abusive applications. The free breathing oversize stainless steel 37mm intake and 42mm exhaust valves ride in bronze silicone guides, and the push rods are special heavy wall units, made to withstand long service. The cam is a proprietary grind of Aero Conversion’s, manufactured by a reputable aftermarket manufacturer, which makes the best use of the 2180cc engine’s ability to create peak torque at the 3000 - 3400 rpm cruise settings.


The AeroVee accessory pieces, such as the billet CNC machined intake manifolds (which are installed without traditional paper gaskets), offer a perfect fit and finish not available from a cast part. THE ENGINE This high level of product finish is obvious throughout the Monnett starts with a factory new, all aluminum case, kit components. The trademark color is a red anodized which is admittedly 14 pounds heavier than the original condition, and it's a striking contrast to the charcoal black magnesium alloy unit. It’s stronger and stiffer than the high temperature paint that the factory used on the protomagnesium alloy original case, and better able to handle type. Quite handsome! As delivered from the factory, the the stresses of the greater power being demanded by left and right engine case halves are unpainted. They modified, bored and may be painted AeroVee engine on the nose of the Sonex tri-gear prototype. stroked engines. any color, with any of the heat Aero-Conversions resistant engine Inc. outsources the paints available at internal components your local auto for its AeroVee enparts store, or gine, the same as simply left bare. most of their compeThe rear casetition. The off road mounted accesracing community sory drive unit, has developed some which besides incredibly strong adapting the enparts for their VW gine to the engine powered vehicles, mount, and the and this technology bolt through has filtered down to mount for the the experimental geared starter, aviation enthusiasts. also carries the The crankcase has ignition modules been modified to and center Aero-Conversion’s mounted alternaspecifications, with tor rotor. internal machining of the case to assure The aluminum clearances for the 82mm forged, counterweighted crank, flywheel disk, with its cad plated steel ring gear (held in and the special connecting rods used. The case halves place with allen cap screws) does triple duty, by: are equipped with four steel case savers per bore which 1. Allowing the gear reduced starter to spin the engine; prevent the thermal expansion of the cylinders from rip2. Supports the magnets which trigger the magnetos; ping the head studs out of the case walls. 3. Carries the incredibly strong permanent magnet which power the 10 amp alternator. The bores themselves and the cylinder heads are maThe 10 amp alternator is standard, and is included with chined to fit the forged aluminum 92mm pistons. The the basic engine kit. An optional 20 amp replacement is engine is set up for an 8.0 to 1 compression ratio which available at additional cost. The accessory case assem-




bly is also a CNC derived part, and carries the red anodized finish as well.


An item of interest to us performance oriented folks, the ignition modules offer only one advance setting, designed to operate at 25º before top dead center. You might find that strange, thinking that the engine would surely start more easily at 10º advance, and most certainly we're leaving some power on the table by not getting the full advance to 30º plus. These are all correct assumptions, but the choice has been made to accept this compromise in order to achieve the simplicity and bulletproof reliability that the rigidly mounted modules offer. The immensely popular Jabiru 2200 engine (certified in Australia) uses a similar and equally reliable arrangement. In typical Monnett fashion, with simplicity being the driving force, a semi-redundant ignition system is offered by way of this design. One of the two ignition modules powers the front pair of cylinders, while the other module provides the spark for the rear pair. In the unlikely case of an ignition unit failure only two cylinders would lose power. The unaffected pair of cylinders will turn the engine at 2400 RPM (35 hp) at wide open throttle, enough to keep the Sonex airborne and allow the pilot to continue to the nearest airfield for repairs. Some folks refer to this style of ignition as the “limp home mode”, but there’s no denying the extra safety it provides. Of additional interest is the fact that this system is a “waste spark” type. The modules fire the spark plugs on every rotation, one of which is the compression stroke as you’d expect, the other is during the exhaust stroke which has no benefit at all, but does no harm. The beauty of this system is in its simplicity, reduced parts count, and low maintenance. Aero-Conversions has great faith in their ignition system design, but does offer the

option of two sparkplugs per cylinder. Some of their customers live in nations were a true dual ignition is required. They also realize that some folks just insist on systems more like the certified equipment that they learned to fly in. If a dual plug set up is chosen, the user must provide a second ignition source such as a magneto or electronic ignition module driven from the original distributor drive. These installations may cause the builder to have to modify the engine cowling since products installed at that location tend to stick up and ruin the low profile normally created by the standard AeroVee engine.


The shrink fit steel prop hub extension (with aluminum drive lugs) is another CNC produced item. Heated to 500ºF and installed (with the use of a specially modified Woodruff key) on the nose of the very strong forged (but otherwise stock) steel crankshaft, it becomes "as one" with the crank. This is part of the “do it yourself” project, as the crank and hub are shipped unassembled. A threaded bolt (secured with Loctite®) is used to provide additional security for the hub. The combination of the lightweight prop hub extension and


lightweight wooden propellers, plus the remarkable stiffness of this massive counterweighted crankshaft, has proven that the bearings are handling the reduced loads well. We’ll cover more on VW crankshafts in the next issue of CONTACT! Magazine.


When queried about the lack of a claimed "TBO", Jeremy Monnett, general manager of AeroConversions, Inc. remarked adroitly that TBO numbers have been a marketing device of the certified engine providers, with no real guarantees attached. The truth is The AeroVee steel prop hub, that an AeroVee shown with out drive lugs. engine, which is operated regularly and properly, and maintained faithfully, is likely to live a very long time; probably 1200 hours or more. Conversely, a seldom flown hangar queen is going to accumulate the acids of disuse, see less frequent service, and possibly need rebuilding in half that time. All engines wear differently, your actual mileage may vary. The issue you might want to look at is, what level of inconvenience and expense will that eventual overhaul cost? In this case, you built the engine originally. Surely a review of the assembly video will prime your recall, and reversing the process should be simple. Now you are faced with renewing the parts intended to wear (bearings, rings, etc.) and checking for damage to those parts which you hope to merely clean and reinstall. But even with some replacement parts involved, the overhaul is going to cost only a fraction of the initial purchase price of the AeroVee “U-Assemble” kit, which is currently under $5,000. This means that the annual cost of operating an engine like this is very low indeed, and in large part, explains why these conversions remain an attractive option to builders and flyers of light aircraft.


The AeroVee engine is one of only a handful of automobile engines converted for experimental aircraft which are accepted as an “insurable“ power plant by the EAA endorsed provider, Falcon Insurance. Although the AeroVee has been on the market only a short period, Falcon accepts the AeroVee’s heritage as proof of quality. Insurance companies like to have something to base their actuarial tables on. The more history, the greater probability that they can charge you a fair and equitable premium, instead of overcharging the experimental builder / flyer because they just don’t know what their risk exposure may be. JP


70 @ 3400 RPM 80 @ 3400 RPM







Compression Ratio

7.0:1 8.0:1

Min Octane

92 Automotive Fuel 100 LL

Oil Capacity

2 3/4 US Qts.

Oil Type

SAE Multigrade 20/50

Firing Order


Spark Plugs

Autolite MP4163 or equivalent


Aero-Carb ACV-C03S



Alternator Output

10 Amp (optional 20 Amp)


158 lbs (no oil or exhaust)

Propeller Drive


Prop Bolt Pattern

Qty 6, 5/16" diameter @ 4" Center

Prop Drive Bushings

9/16" diameter X 7/16" Long

Battery Requirement

12v @ 20 amp



Cruise RPM

3200 +/- 200

Maximum RPM


Oil Temp. Min.

160º F

Oil Temp. Max.

230º F

Oil Pressure Min.

20 psi

Oil Pressure Max.

100 psi

Oil Pressure @ Cruise

40-50 psi

CHT @ Cruise

350-375º F

CHT @ Climb (5 min)

420º F


450º F


1400º F


By John P Moyle Associate Editor The Aero Carb, by Aero-Conversions, Inc. is the latest in a long line of guillotine slide-type "throttle body fuel injectors" which have come along since the original Lake brand unit became available thirty years ago. John Monnett flew behind one of these way back when, and saw the potential in the design. Rumors that the Aero-Carb is just a “warmed over Posa” is simply not true. Several companies have made TBI's of some semblance to the “Lake TBI” throughout the years, some are still in business, others are not. Monnett has taken the design to an all new level.


Model ACV-C03 mounted on a C-85

The entire unit is CNC machined from billet 6061-T6 aluminum, and has only two moving parts. The carb is delivered in Aero-Conversions’ trademark red anodized finish, and is available in throat sizes from 26mm to 38mm. There is a unit available for most light aircraft applications, whether your plane features a half VW, a four cylinder Lycoming, or something in between.

tors in place. You are free to do aerobatics with the Aero Carb, as long as you keep it supplied with fuel pressure!

The device is simplicity itself, with a single needle to fine tune for best performance. Three needle sizes are provided with each carb to assure that one will meet your needs. The flat plate slide is the principal control and when wide open, clears the air passage completely. Since there is no butterfly type valve in the throat (there isn’t really a traditional style venturi involved), there is not an obstruction onto which carb ice can easily form. Never say never, but the opportunity has been greatly reduced. Air filters are available and carb heat can easily be adapted to the intake side of the carb as befits your installation.

The mount style of a four bolt flange on 1-15/16" centers (same as Continental or Lycoming) may be chosen, or a spigot style for connecting to a 2" hose mount. Either model costs $395.

The cockpit actuated push-pull cables, which control both mixture and throttle position, attach to built-in mounts machined into the exterior of the throttle body, and are held secure with stainless steel set screws.


The original throttle slide, made of Delrin, has been found to occasionally swell from being subjected to higher temperatures, rendering the carb somewhat inoperable by having the throttle stuck in one position. A required service bulletin was issued to check (with a feeler

The Sonex factory prototypes have only a basic air filter attached, but the Aero Carb is positioned directly and closely between the left and right exhaust headers in this tightly cowled aircraft. A passive, "always on", carb heat system?? No one at the factory made such a claim, but they do seem satisfied with the set up as it stands. There is certainly enough humidity to create carb ice scenarios in their part of Wisconsin, so it's likely that if the Aero Carb were susceptible to icing, the factory Sonex pilots would have encountered it in the last few years. The only other moving part is the mixture control, which also features complete idle cut off. No dripping of fuel on the ramp or your hangar floor!! There is no float bowl, so the unit may be mounted in any orientation, updraft, sidedraft or downdraft. Gravity feed is perfectly adequate, but pressure systems may be used with proper restric-

Checking the gap between the Delrin slide and the carb body.


gauge) the clearance between the Delrin slide and the side of the carb body . The gap must be between 0.0060.010 inches on each side. If the gap is under 0.006 inches, the bulletin instructs the owner to remove the slide from the carb body, and remove “some material”, using a flat piece of 100-150 grit sandpaper Current production models now come with Teflon coated aluminum slides. This new slide is available to all current Aero Carb owners, for $25 plus shipping. A recent optional service bulletin from Aero Conversions suggests that there may be a minor bit of filing to be done on one side of the new aluminum throttle slide. In this case the engine side of the aluminum plate may "dig into" the milled cavity fillet, so rounding of the edge is required to prevent this friction which might cause the slide to stick. Another required bulletin which came out in June of 2003 reads, “NEEDLE TOLERANCE CHECK: All Aero Carb needles must immediately be checked for proper sizing.”

FEATURES:                 

Works in updraft, sidedraft, or downdraft configurations. Gravity feed... no fuel pump required. Fast, dependable starts. Resistant to carb icing. No float bowl. Approved for aerobatics. Only 2 moving parts. Easy to tune, only 1 adjustment. 3 metering needles included. Integral cockpit-controlled mixture and fuel shut-off. Push-pull throttle and mixture cable mounts are built-in. Precision CNC 6061-T6 billet aluminum construction.

Spigot (hose) or Flange mount (std. 4 hole). Model sizes available: 26, 29, 32, 35, & 38mm. Aero-Carb flange-mount option. 2.5 inches square. 5/16 inch mount hole diameter. Holes located 1-15/16 inches center to center. Fits standard continental and Lycoming mounts.


Aero-Conversions offers an optional intake air filter assembly, anodized to match the Aero Carb. Rough dimensions: 2.625" x 4.375" in diameter. The cost is $50.

Checking the needle diameter. “It should measure between 0.123" and 0.125" in diameter. If you discover any of your needles are larger than this, the needle must either be polished until the proper diameter is achieved or returned for replacement at no charge. Note: All Aero-Carbs have Needle Orifices reamed to 0.127"

The optional air filter kit. Pictured to the left is an optional throttle link arm, designed to increase throttle throw and decrease throttle pressures (via mechanical advantage), and also provide for an alternative throttle cable routing. $30 Another quality built option is the “Intake Adapter Flange”, which for an additional $35, you can bolt common air boxes to the intake side of your Aero-Carb. JP Moyle


Sonex: A design Overview, continued from page 9 This process results in a seamless unit of substantial thickness which is very difficult to puncture, and even harder to "burst". The design for the Sonex includes the fuel filler neck as well as sites for the fuel drains and gauge attach points. Located in this case between the instrument panel and right above the carb mount, all the connections are short runs. More overall simplicity, this time adding to ease of assembly.

A note from William Wynne on Fuel Tanks Fuel systems for homebuilts need to be looked at from two different angles. First, is the system so complex or unreliable that it will likely cause an engine stoppage or power reduction, and separately, how will the system fare in a crash? The second issue must always look at the airframe factors to be valid, i.e., if a plane has a steel tube fuselage and lands at 25 mph, you are less likely to deform the fuselage and break a tank inside it. There are too many type one accidents related to fuel systems in homebuilts. I think it stems from complex systems which require a lot of pilot thought or procedures to operate. The worst ones have a lot for the pilot to do, are electrically dependent, have several vents, and have electrically dependent gauges. The Sonex system stands in contrast to the poor records of more complex designs. In contrast to some complex homebuilt fuel systems there is the J-3 Cub. There have been very few fuel system accidents in cubs for the millions of hours flown in them by nonprofessional pilots. This good record is due to the simplicity of the system. No pumps, one tank, one valve, which is not operated in flight. A non-electrical gauge with vent visible to the pilot. The Sonex system is about as close as you can get to the venerable J-3. In an accident, the Sonex has a big advantage not available to designers of the cub 60 years ago, the plastic tank. These have been around race cars for many years and have a very good record. I have seen well made aluminum fuselage tanks take some very hard shots, but I am sure that the plastic tank would be better in almost any case. If you question this, go buy a five gallon plastic fuel tank from your local auto parts store. Fill it with water and drop it from a 3 story building, and then hit it with a sledge hammer. Aluminum wouldn't like this, and fiberglass wouldn’t stand a chance. Again, the Sonex’s low landing speed is a big factor in its favor. ~William Wynne


This view of the instrument panel shows the sight-tube on the right side

The plans call for a simple sight tube affixed to the right side of the instrument panel, as shown in the drawing to the left. As previously mentioned, the fuel tank is molded with this feature in mind. Sonex builder Jack Lockamy (mentioned previously in this issue) wrote a comment on an optional fuel gauge system:


Sonex-LTD sells the Princeton Electronics fuel probe that is designed specifically for the Sonex fuel tank. It utilizes an un-used threaded fitting on the lower portion of their fuel tank. No modifications required. Apply your favorite thread sealer, install, hook up a couple of wires, and you have an electronic fuel sender. The probe is available for the standard analog fuel gauges (30-240 OHM if I remember correctly), or the other probe which is compatible for use with the Grand Rapids EIS and/or Stratomaster Display. Princeton Electronics was working on a Sonex probe that could be used both for analog and digital gauges if I remember correctly. This way you could upgrade from a steam gauge to the EIS or Stratomaster without purchasing a second probe. The probe will cost you more than $24.... but the fuel tank and the glare shield don't have to be modified. Spend money... save time! ~Jack Lockamy


The wings of this plane are basic rectangular panels, with no wiring nor plumbing, except a pair of plastic pitot/ static lines within the structure. Simplicity breeds reduced effort, and fewer opportunities for errors. The spars overlap in the fuselage center section and attach to the spar box with tapered pins like those commonly found in exotic sailplanes. The aileron and flap controls are easily disconnected by accessing the attachment hardware under the flip-up metal seat pan. Removing the wings takes approximately 10 minutes, whereas reinstalling them takes 2 people approximately 15 minutes. The flaps are quite large and very effective in reducing the landing speed to 40 mph. Sonex incorporates a NACA 64A415 airfoil with a pair of milled aluminum spar caps, formed aluminum ribs, and riveted 6061 wing skins. The 22-foot wingspan provides 98 sq. ft. of wing surface. The wing tip is simply a 45° slash at the end of the wing, with a flat skin cap riveted in place. The tail surfaces feature preformed fiberglass tips.


As previously mentioned, close attention must be paid to the CG. It’s pretty straightforward for the most part, load the plane to gross with full fuel and passengers, and the plane will be within all limits, even as fuel is consumed. Here’s an example: Weight





















Pilot and Passenger Total

67.39” appears to be well within the envelope. Notice in the table above, the upper right hand corner is chopped off to approximately 68.12”(or by looking at the bottom of the chart, 28% of MAC) when loaded to gross. This is to account for the migration of the CG, caused by the consumption of fuel. Checking the Sonex website, the specifications call for an empty weight of 600#, but after speaking with Jeremy Monnett on the issue, he advised us that we should use the more realistic basic empty weight of 612# in our calculations, as most of their builders are seeing higher numbers than the original prototype’s 562# weight. The W&B of this plane is pretty simple all in all, until you start to fill the baggage compartment. The baggage compartment is rated at 40 lbs max. One might think that if you have 40 lbs less in the passenger compartment, then you can add 40 lbs in the baggage compartment, and not exceed gross. This is entirely true as far as gross is concerned, but it’s not that simple for balance. In the above example, 392 lbs is the most you can allow for passengers, with full fuel and no baggage. But should you try to install 40 lbs worth of property in the baggage compartment, and simply deduct 40 lbs off you passenger payload, you’ll be aft of the aft CG limit, albeit not by much. The choice of the engine plays a big part on the W&B issue. Although heavier engines reduce the useful load, they take some of the pressure off the aft CG condition. When we tried to do a W&B based on the numbers supplied as examples in the POH, (I’ve been informed that these are the prototype’s numbers) full fuel with the passenger compartment loaded to gross, caused an aft of the aft CG condition, which is worsened by the use of the baggage compartment. In all cases, careful attention should be paid when using the baggage compartment.



You may exercise your creativity while equipping the panel, and while it isn't gigantic in size it is completely adequate for the "day VFR mission" for which it’s intended. Sonex Ltd. offers several compact LCD screen multiinstruments which are very compelling and cost effective. The Stratomaster Ultra includes all the necessary basic

The Stratomaster Ultra can be used in just about any aircraft with just about any engine. flight instruments and a complete suite of programmable engine monitoring features. Everything you need to know about the engine, fuel system, electrical system and flight control data is right there on screen. This unit is available starting at $1050. It's highly debatable whether an individual could place the equivalent analog gauges and instruments (available in this one compact unit) in the relatively small area of the Sonex panel, if he chose to attempt it. Even if it were possible, the completed panel would weigh more, and almost certainly cost more than this single digital instrument.

lb maximum installed weight.” The appropriate engine mount will be provided for your power plant selection within the Easy Build kit. Since the engine mount incorporates either the main gear sockets for the tail dragger, or the nose gear support for the tri gear, selecting the proper mount for your engine and landing gear configuration becomes an important decision right up front. Sonex also offers a variety of wood or wood composite Sensenich or Prince propellers (depending on your application) for the above engines, at competitive prices. The standard billet aluminum crush plate / prop spinner that comes with the kit fits these props exactly and looks very sharp indeed. Those taking advantage of the "maximum shortcuts" may expect to complete their plane in 700 hours, give or take. The designer always hopes that you are realistic about your ability to apply your available time to a project of this nature. But remember to have fun!! It has been proven that first time builders with no unusual skills or experience are able to complete this aircraft kit in a timely fashion with only a few tools not common to typical garage workshops. The list of required tools may be seen on the Sonex website @


The prop spinner included with the Sonex Easy Build Kit


The Sonex remains available as a plans-only project, for the frugal and the hard core do it yourselfer. Plans are available for $600 USD. Shipping & handling, and free admittance to one of the factory’s very popular Builders Workshops is included. The plans include specific instructions for each of the factory approved landing gear styles and all three approved powerplant installations.


The latest version of the Easy Build kit has advanced to the point that it's a real bargain. The complete Easy Build airframe kit is still $11,950, however an additional $500 needs to be spent at Aircraft Spruce or Wicks for the hardware kit. An additional $250 or so will get you the set of brakes, wheels, and tires. Your selection of recommended engines include the $4950 80hp AeroVee “UAssemble“ engine kit, the fully assembled $9,200 80hp Jabiru, or the larger and more expensive $12,900, 120hp 6 cylinder Jabiru, but as their website states, “Sonex may be powered by alternate engines 80 to 120 hp, 200

is unique and shows again Monnett’s desire to create simple yet clever ways to make your airplane easy to build, yet safe and efficient. All of this in a spinner?? You bet! All approved Sonex engine installations require the use of a wood or wood composite propeller. Every wood prop must have a crush plate on the front to properly distribute the torque applied when the prop is installed, and at each scheduled re-torque. Designing this spinner from solid aluminum billet , (CNC mill shaped to match the propeller’s center dimensions and the shape of the Sonex cowl), Monnett eliminated the usual fussy spinner installation. Normally, a precision made round backing plate sandwiched between the prop hub and the prop itself, followed by the crush plate and a second round spinner support plate to keep the pointy


end of the spinner from developing a case of the wobbles. When the prop has been bolted in place and properly tracked, then the spinner body can be installed with a significant number of screws into the base plate. By contrast, the solid aluminum nose cone provided by the Sonex factory is only one part. The prop is placed on the hub, the spinner is placed over the center of the prop, and the prop bolts are slid into the machined cavities in the spinner, through the wood prop, through the drive lugs, into the hub and nutted in place. The bolts are then torqued, with the wide base of the spinner acting as the crush plate. As you can see, many parts are simply eliminated, it's all much less complex, and there are as a result of lower parts count, few chances to make mistakes. Simplicity breeds safety. once again!


It’s probably an overstatement that there might be any controversy at all, but as one might expect once a new design has been on the market for a while, and experimental aircraft builders being the interesting and resourceful people that they are, the evolution to nonstandard engines has begun. Del Magsam has flown his Sonex with a Corvair conversion as the power source. This six cylinder horizontally opposed air cooled engine seems like a reasonable alternative, but it is heavier than the factory requires. The approved powerplants all come in under the mandated 200 lb. firewall forward maximum. Magsam has worked diligently to achieve an all up weight around 220 lbs, and shows some real engineering skill in moving the center of gravity as far aft as possible, including a low rear mount starter which is actually cantilevered behind the engine into the space created by the Sonex’s unusual 30 degree raked firewall. The battery has been moved behind the seats to help balance the additional forward weight. The very clever installation makes use of the Sonex factory Volkswagen engine mount, and fits entirely within the standard unmodified cowl!

mental aircraft contains exactly the kind of people who like to apply their own ideas to the planes they are building. The designer fears having someone with less ability make a serious mistake which not only could get a customer hurt, but might end up besmirching the good name of the aircraft design. (The average non pilot can pick out an EZ on the flight line, and recognize it as the “John Denver” plane.) It’s not hard to understand that the years of hard work, and the major investment of the original designer could be put at risk inadvertently by a creative person just looking to enjoy his experience in the world of homebuilts. Clearly there is no easy answer here. Every designer faces this crisis in some way, and John Monnett won’t be spared the agony of this concern. He has provided a short list of affordable engines approved for the airframe. Prices from under $5,000 to almost $13,000 are pretty low compared to anything from the certified engine folks, used by many other designs. Del Magsam found that he could build a fresh 100 hp engine from a salvaged core for under $3,000. That’s more power than the AeroVee, at a lower cost, but there is the weight penalty. Again, no easy answers, you have to come to you own zone of comfort. Don’t expect any advice from the factory, they’ve never built YOUR airplane! On the other hand, they’ve built many examples of the Jabiru and AeroVee powered models and are the experts in the field, and more than happy to share their experiences with you. Expect to read more about Del’s flying Corvair in the upcoming CONTACT! issue #75.


Understandably, the designer is concerned about the installation and use of engines outside of the recommended parameters. They cannot possibly test every alternate engine which builders become interested in, and they have no control over the quality of the work that the adventurous may Photo courtesy Del Magsam produce. It’s a dilemma. The target market for experi- Del Magsam's Corvair installation has become quite controversial.


If you are amongst the gravitationally challenged, outside the 95th percentile of human norms, then John Monnett may be your new best friend. While he is nowhere near being a large man himself, he has designed an aircraft which is almost entirely unique in its ability to encompass a man of major dimensions comfortably. If built with the single center control stick, a standard Sonex is able to accept a man of 350 lbs, place him in the middle of the The series of photos below, show’s “Big Bubba” John Moyle trying on the Scheppers Sonex for size.

John Moyle sitting in Del Magsam's Sonex. Del’s seat pan is installed lower than Eric and Jennifer's. full width seat astride the stick with his legs spread out to use the outer two rudder pedals. Plenty of elbow room, and all controls within reach. The canopy is about seven inches taller at its center than at the "top of the head positions" for normal side by side passengers, thus our vertically enhanced pilot gains the needed additional headroom without altering the airframe in any way. The lack of any sort of center console allows this unusual option for those who qualify as "Big Bubbas". Not sure if I'm talking about you?? Do you shop at the Big and Tall shop? Does your car make a sucking sound when you exit through the door quickly? Does the manager at Hometown Buffet weep when you arrive? Do you instinctively duck when entering rooms? Have you noticed the designers of the show planes at Oshkosh trying to avoid eye contact with you? Have you been reminded repeatedly by amused Ultralight owners that their plane weighs less than you? Yes my friend?? Welcome to Big Bubba World!! But what about the other guys, those who are not quite Bubba? Read Pat Panzera’s report on the next page. JP Moyle


By Patrick Panzera Editor

to the seating arrangement. I understand that the seat pan itself can be lowered two inches, and that could make a big difference. That would definitely help with the head room issue, but I don’t know what else it might do for a guy my size. In my opinion the seat pan should go down, and the seat back (which is a very rigid, highly structural member) should be moved aft at least another 4 inches to accommo-

Piloting Eric and Jennifer Scheppers meticulously crafted Sonex, I found my only complaint with this design is the fact that I didn’t fit in it very well. I’m not an overly large individual by my estimation, 5’-11’ and 210 lbs. Being long legged, there just wasn’t enough leg room for me to be completely comfortable. Once the headphones were put on and the canopy shut, I needed to tilt my head to keep from banging up the canopy. Shoulder room was adequate. I’m rather broad in the shoulders and Eric is a little smaller than me, and between the two of us we were fine. You have to make concessions. It’s not like your typical Piper where you have a little bit of elbow room, but for a small airplane, I really wouldn’t complain about the 40” of shoulder room. Elbow room is another story, as there wasn’t quite enough. I had to keep my arms pretty much folded in front of me when I wasn’t flying. Foot placement is the real issue though. Perhaps if I were on a long cross country, I could put my feet between the rudder pedals so I could stretch my legs. But otherwise, while Eric was flying and had control of the rudder, I didn’t want to restrict his movements in any way, so I had to keep my feet flat on the floor, which was not a very comfortable position at all. If I were a little longer in the legs, my knees would be hitting underside of the instrument panel, and with any gust or bumps, my knees did hit from time to time. All in all, feet flat on the floor wasn’t too bad of an alternate seating position but to go an entire flight like that would be unacceptable in my opinion. The seat back came across just below my shoulder blades, (leaving the rest of my upper torso unsupported) and was incredibly rigid. It was actually quite painful for most of the flight, although we were only up for about 30 min at the most. If it were my airplane I would be making some major changes

Trying to keep one’s feet off the ruder pedals can be uncomfortable for one with long legs. date a 6 foot pilot comfortably. I don’t know if such a modification is possible or not. As for the flying experience itself, it is perhaps one of my more favorite flights to date, as far as just pure enjoyment. It was a little bumpy that day. We took the Sonex up to about 3,000’ AGL hoping we could climb out of the bumps, but it didn’t help much. The airplane operated as expected. I didn’t have a tendency to over control the airplane while doing steep turns and other maneuvers. I was able to pretty much look where I wanted the airplane to go and it would go there. Very responsive in roll, perhaps a little sensitive in pitch. It wouldn’t take too many degrees of pitch change to bring about a noticeable airspeed change.

A bit cramped in the right seat, for my 5’11” frame.

During climb-out we were indicating approximately 110 mph and 500 fpm. The outside air temp was probably 67° F. Barometric pressure was 30.3 After about a 1500 ft climb Eric asked if I wanted to take the controls. It took a very slight amount of right rudder to keep it flying coordinated, a lot less than I expected. It took virtually no rudder to keep it flying straight and level, and in slow flight, again, not very much rudder, not nearly what I am accustomed to in other aircraft. A two minute turn at cruise speed took little or no rudder to stay coordinated. As I steepened the bank, more rudder was needed, just as one would suspect. We were seeing 60° and


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Volume 13 Number 2 Mar-Apr 2003

Issue #73

Reprinted June 14, 2006 MISSION CONTACT! Magazine is published bimonthly by Aeronautics Education Enterprises (AEE), an Arizona nonprofit corporation, established in 1990 to promote aeronautical education. CONTACT! promotes the experimental development, expansion and exchange of aeronautical concepts, information, and experience. In this corporate age of task specialization many individuals have chosen to seek fresh, unencumbered avenues in the pursuit of improvements in aircraft and powerplants. In so doing, they have revitalized the progress of aeronautical design, particularly in the general aviation area. Flight efficiency improvements, in terms of operating costs as well as airframe drag, have come from these efforts. We fully expect that such individual efforts will continue and that they will provide additional incentives for the advancement of aeronautics. EDITORIAL POLICY CONTACT! pages are open to the publication of these individual efforts. Views expressed are exclusively those of the individual authors. Experimenters are encouraged to submit articles and photos of their work. Materials exclusive to CONTACT! are welcome but are returnable only if accompanied by return postage. Every effort will be made to balance articles reporting on commercial developments. Commercial advertising is not accepted. All rights with respect to reproduction, are reserved. Nothing whole or in part may be reproduced without the permission of the publisher. SUBSCRIPTIONS Six issue subscription in U.S. funds is $24.00 for USA, $28.00 for Canada and Mexico, $40.00 for overseas air orders. CONTACT! is mailed to U.S. addresses at nonprofit organization rates mid January, March, May, July, September and November. Please allow time for processing and delivery of first issue from time of order. ADDRESS CHANGES / RENEWALS The last line of your label contains the number of your last issue. Please check label for correctness. This magazine does not forward. Please notify us of your date of address change consistent with our bimonthly mailing dates to avoid missing any issues. COPYRIGHT 2006 BY AEE, Inc.

80° banks. Minimal back pressure was required to keep constant altitude. Very comfortable, very docile, very predictable. However the roll rate was enough to be exciting. It was controllable but yet still fun. I didn’t find it to be overly pitch sensitive, where some pilots might, but otherwise the controls felt relatively balanced. I didn’t really notice it being more sensitive in pitch or roll, to the point where the aircraft was uncomfortable or unmanageable in any way. Flying the Sonex is something that most people should be able to get comfortable with in short order. The view out the windscreen while in straight and level flight was a bit disappointing. Check out the cover shot in this issue, and note that the plane cruises rather level, not seriously nose down like I expected. Note too the amount of instrument panel and cowl that can obscure the view over the nose. Visibility over the panel when the tail is on the ground seemed to be excellent, only minor S turns were needed during taxi to verify we were on centerline. After landing, it occurred to me that if the seat were lowered to where my head didn’t hit the canopy, the great view over the nose would diminish. When I took the controls (on the ground) the rudder response was a lot better than I had anticipated. Since the Sonex is not equipped with differential braking, the rudder response seemed to have been designed very well to make up for it. The amount of control input was very intuitive, and there was virtually no tendency to over steer like some tail draggers I’ve flown. The Sonex is a very docile tail dragger in my opinion, although my tail dragger experience may be limited. The Sonex seemed to me to be more controllable than a Citabria, Cub, Champ, or even Taylorcraft in my opinion, The tail wheel is actuated by a solid tiller rod which probably accounts for most of the positive control feel. All in all, I give the Sonex high marks for performance, as it’s very fun to fly, while not being difficult to handle. I’d like to thank Eric and Jennifer for allowing me to see first hand just how nice their little Sonex is to fly!

I’d like to thank John Moyle for the effort he put in to bringing the story of the Sonex to us. Unfortunately I couldn’t get it all in this one issue, so some of it will be carried over to the next issue. One item in particular, while we were putting the finishing touches on this issue, Sonex Ltd. announced the successful first flights of 2 more aircraft! The Xenos (Sonex spelled backwards) is a “Y” tailed two-place all-metal motor glider powered by the same engines as the Sonex. The other prototype to take to the sky is the new Y-tail Sonex derivative named the Waiex. (pronounced “Y-X”, and stands for “Y-tail Experimental”. We’ll cover these new planes in issue #74, which is already taking shape. Issue #75 will be another “theme” based issue, as we are putting together articles on the Corvair engine conversion, gathered from several of our readers who are actively pioneering the use of the Corvair engine in their particular experimental design. I’m really looking forward to this issue, as the Corvair engine has gone overlooked far too long. Since the last issue of CONTACT! I made my first ever trip to Sun ‘n Fun and met a lot of loyal subscribers who helped make my first visit memorable. The chores in the CONTACT! booth kept me away from the flight-line where the future articles are parked, but I did manage to visit the other vendor booths to gather information for a few future articles. I also managed to pick up several new subscribers, who I would like to welcome aboard! When I wasn’t in the booth, I spent quite a bit of time in the engine forum area where I met a few individuals with some interesting engines. We’ll be reporting on these and other engines in future issues of CONTACT!

Pat Panzera


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$650 $600 $308 $150 $1,500 $5,000 $9,500

DONATE YOUR PLANE, PARTS OR PLANS: The first ever “for aviators by aviators” charity needs your support. Receive tax benefits for a charitable contribution, donating your plane or any of your surplus parts and/or materials. See page 22 of CONTACT! issue #72 or visit for information on our 501 (c)(3) charity. CONTACT! Magazine (559) 584-3306

For Sale: B0208/MFI-9 (Messerschmitt built) A unique recreation of the mini-coin Biafra Baby #BB905. Historically accurate and documented. New zero-time TMX IO-240. A highly maneuverable small ship for a small pilot. Registered Experimental/Exhibition warbird. New prop, paint, interior, instruments, wheels and brakes. NOT LSA qualified. Contact for brochure or go to for images under “current project.” Priced at $38k FL59 Ft. Myers FL. Partial or full trades for aircraft or vintage racecar considered. Don Black 107 For Sale: Instruments- Falcon GH-002 3 1/8" Vacuum Attitude Gyro ACS 10-22955 $250 * Airborne 1J7-1/D9-18-1 Filter ACS $25 * 4" Venturi ACS 15050 $35 (has fiberglass streamlined housing) These units have about 300 hours total.* CONTACT! Magazine (559) 584-3306 103 For Sale: Subaru EJ-22 Firewall Forward. 300 hours TT w/o any problems. Ross redrive, all electronics, engine mount and some spare Subaru parts included. See CONTACT! issues #6 and #8 for a full description of this engine as installed on a Dragonfly. $5,000 Ruidoso NM. Randy (575) 937-3586 102 For Sale: Two RV6 Motor mounts for 4.3L Chevrolet V-6. One tail dragger, one with nose wheel. $1,000 each. Ruidoso NM. Randy (575) 937-3586 102

Wanted: Tuned port fuel injection system for my Ford Windsor 351W (See CONTACT! issue 16) which would be fed by my McCulloch (Paxton) supercharger, with each cylinder's injector adjustable and all mixture leanable. For Sale: Prince P-tip propeller with Gates 2.67:1 PSRU and Polychain Kevlar belts, Used 40+ hours on O'Neill Magnum V8 “Pickup” with modified Ford 351W, with and without McCulloch (Paxton) supercharger, 260 to 380 HP. Spinner included. Engine not included. $800 For Sale: Torsional vib. damper, for Lyc O-320. $180 For Sale: Female molds for wingtips for NACA 4412 airfoil, 63" chord. $170. Terrence O'Neill 103

ALTERNATIVE ENGINES VOLUME 3 The third in the series from Mick Myal is available only through CONTACT! Magazine. See the back inside cover wrap of this issue for ordering info or visit For Sale: 3.8L Ford V6 with Blanton redrive, as pulled from an RV-6 shown on by searching for “V-6 airplane engine” (yellow plane). Includes three-blade Warp Drive prop, all manuals and engine instruments. $2,000.00 Buyer pays shipping from Benbrook TX. (817)692-6742 Richard 102

ALTERNATIVE ENGINES VOLUME 2 Once again available! See the back inside cover wrap of this issue for ordering info or visit For Sale: Glasair 1 TD kit. Fairly complete, unstarted kit with extras. $4500.00 Located in Hanford California. Please contact Pat Panzera with your questions or offer. CONTACT! Magazine, 559-584-3306 106 For Sale: Ross Redrive with aluminum flywheel. $1800.00 For Sale: Warp Drive Propeller threeblade, 66” diameter, left-hand rotation with nickel leading edges. Comes with spinner. $500.00 Or buy both for $2000 total. These components were bolted to a Subaru EA-81 and tested for a maximum of 30 minutes only. Buyer pays shipping from Las Vegas NV 89104. Don Thompson (702) 236-1691 106

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WE HAVE HATS! Yes, for $15.00 plus shipping, we can send you a beautiful 100% cotton ball cap with our CONTACT! Magazine logo embroidered on the front. The hat is black with white lettering, and for the ladies we have pink with purple lettering. Please specify: Men’s Women’s United States $15.00 + $5.50 s&h Canada/Mexico $15.00 + $8.50 s&h Overseas $15.00 + $15.00 s&h We are pleased to announce the publication of yet a 4th in the series, "ALTERNATIVE ENGINES VOLUME 4". Over 350 pages of black and white or color content, compiled from past issues of CONTACT! Magazine as published by Patrick Panzera, editor of CONTACT! Magazine.

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