Sonex* Build Strategies

*This web site is NOT owned or managed by Sonex, Ltd.. Sonex, Ltd. is not responsible for the content unless explicitly stated. See Disclaimer.

What you have stumbled upon here is a long-winded rant about building an airplane inexpensively. Well, that's an oxymoron. More correctly stated - building an airplane relatively inexpensively. Relative to its size/performance competitors in this case.

There are no pictures on this page.

This page is my opinion, and is worth exactly as much as you paid for it. This is being written from the position of completing about 125% of a Sonex, but never having registered, licensed, or flown what I built. That is the result of personal circumstances, not my intentions or desires, but that's life. Even so, I do not regret the experience. I have learned a few things that might guide future airplane building work. Here they are - maybe some of this could save you some time, money, or help you get started in a way that successful completion of the project might be more likely. Disagree all you want - it's your airplane to build, should you so choose.

Throughout this rant, I will touch on concepts that are distinctly not emphasized by airplane kit manufacturers, or at the big airshows, or even by EAA (as much as it emphasizes world-class restorations, extremely well-built and expensive kit completions, etc.). It is important to consider where these groups are coming from - they are in business to make money and draw in more customers. The people at Sonex do a good job of acknowledging the other side - the builder's side of an airplane project. Sure, they have headed towards "complete kits", but through my description below I hope to show how they designed their product such that complete kits are not necessary, and great results can be obtained through less expensive means.

Choosing to build

Choosing the airplane

I'm not going into the aspects of choosing to build or choosing the airplane other than to say that the Sonex is an excellent choice for the first-time builder, would be easy for a "repeat offender" to complete, and has performance, given its size and power limitations, to satisfy either.

The low $$$ strategy for building a Sonex...

Key points: buy as little material as possible at any given time, and only buy/build more when you have exhausted all you have.

Application of the strategy:

Do not worry about completing assemblies or riveting things together at first. There are plenty of parts to be made, and enjoy this part of the hobby. Make parts. They will go together very quickly when the time comes.

Invest enough up front in terms of tools and workshop such that the project is fun and not a struggle.

Sonex-specific points of the low-cost strategy:

Don't be too concerned with amassing a complete pile of raw materials. If you have a local source (or even a mail order source) for aluminum, minimize your storage requirements and cash outlay by purchasing in small quantities. Work the material at hand. Even though a complete Sonex requires only about $1500 worth of metal, one may as well keep $1400 of that in the bank for a few months until the first couple of sheets are turned into airplane parts.

Don't buy the Sonex rivet kit ($600) for over a year. If you can stand it, you can even have assemblies finish drilled & deburred for riveting, but not riveted.

Don't buy the Sonex wing spar extrusions ($400) until well into the 2nd year. There are hundreds of (less expensive) parts with which you can become familiar with your bandsaw.

Many people seem to be buying these either at the time of plans purchase, or soon after as an indication of serious intentions. These parts are expensive, they are large, and they don't need to come into play until after one has made the hundred or so other wing parts, and the wing doesn't need to come into play until after the fuselage. Those who have expressed a desire to do the wings first due to storage space requirements - why not do the simpler and less structurally critical fuselage - it can be completed in cleco, and then disassembled and stored flat in the same place and space currently dedicated to flat sheet storage.

The wings, assembled, would be best stored in wing racks. When done, they are quite a bit longer than the fuselage parts (tailcone sides, turtledeck sheets, cockpit sides, tailcone floor). And since they involve the carving of 4x$100 pieces of metal, why not gain metal carving experience on hundreds of less $$$ pieces first?

For much more building entertainment, consider the Sonex-pre-bent metal kit ($800) before the spar extrusions. You will end up with many, many more airplane-looking parts to admire in the workshop, and will be many, many more hours closer to completion with the pre-bent kit shaved down to parts.

Don't buy the Sonex welded parts ($2500, also sold as separate parts) until everything is riveted & the wings are done. The only exceptions here are the tailspring mount (same tri-gear or taildragger) and the elevator horn. But even these aren't needed until well into the riveting/assembly process. And as of this writing, Sonex was selling these separately and applying the package price discount when the rest of the parts are purchased.

Looking back through my pages, I would even hold back on the elevator horn. The horizontal stabilizer is completed without it, and by leaving the elevator root ribs undrilled/unriveted, the horn can be incorporated much later in the build process.

Don't buy the Sonex canopy, fuel tank, cowling, etc. until all of the metal parts are assembled.

Don't buy the engine until the whole airframe is sitting in the garage or hangar, complete & rigged. This is proving to be the most expensive lesson I ever learned about airplanes. Note that the Jabirubuilders mailing list is owned U.S. distributor, and he practices selective archiving of that list. These archives essentially are a collection of marketing hype for the engine - bad experiences with the engine or its distributor are not recorded.

New 2/24/01: The Jabirubuilders list has been closed. The website of the former U.S. distributor is no longer available. Hopefully the new distributor will learn that the major mistake the former distributor made was to not float his prices daily against the Australian dollar. Through the internet, it was found that the NZ distributor would float his prices, which, around the time of Oshkosh 2000, were roughly $4000USD less than what the U.S. distributor charged. I would still recommend checking with the NZ distributor (Mr. Ashley Johnston, for the AUS$ price, and challenge the new U.S. distributor (whoever that might end up being) to meet it. Last I checked (about 3 months ago), one could get a 3300 in the U.S. through NZ for ~$9400USD, and a 2200 for ~$6300USD. That includes a profit for the NZ distributor which he considered fair enough (based on the AUS$ MSRP), so the $11400 currently offered in the US may include $2000USD profit above and beyond the AUS$ wholesale-to-retail markup (assumes AUS$ price has not changed in last 3 months, and that the AUS$ still has an unfavorable exchange rate with USD, but see for yourself).

The above lessons about Jabiru sales only cost me a couple thousand USD to learn, so this might be the best value in free advice you ever read. Now that Mark is out of business, a few other things - he booted me from the email list not long after I started advertising my engine for sale (why, I might say something bad?), and he was VERY selectively archiving the email list.

New 5/27/01: From the Sonex site, they have become a distributor for the Jabiru engine. They also mention that the price will float. This is great news! It's been said that great airplanes only become great by flying with a great engine. The Jabiru has always been a good engine, if not the best thing going in its weight/power class. Now that the Sonex guys have more direct involvement in their powerplant, the winning combination is complete.

While I'm here, the Sonexbuilders mailing list is "owned" by an independent entity not the Sonex company. So other than virus-infested messages or messages that are clearly spam or containing huge attachments, I would expect to see all of the list-generated info - favorable and unfavorable collected in the archive. If you look through the archive and notice that there isn't much of anything unfavorable there - it means that there just isn't much unfavorable to be said.

Don't buy the instruments/avionics/radios, etc. until the whole airframe is completed.

Also as of this writing, Sonex "option" packages are presented on their website to give the customer a combined price for budgeting purposes of the numerous items needed - they are not discounted purchase packages. As such, why not buy them as needed? In any case, there is easily a year, maybe two, during which you will only need the plans and raw materials. (They do offer some discounted purchase packages.)

During this time, someone will come up with a slicker way to do the tail tips/wing tips/cowling/canopy, etc. You may want to incorporate these improvements. Don't lock yourself into a given configuration until the last possible moment. The basic airframe design of the Sonex is easily adapted to change - of some small details. You will, however, add lots of time to the project if you like to make "improvements". It goes together just fine exactly per print.

One rational explanation I have heard for rushing into buying as many components as possible is that the company may disappear, leaving the builder stranded. For one, the plans are such complete documentation that even if the company disappeared, other builders could easily step in to provide the parts - including all of the welded parts, and even the fiberglass cowling and canopy are completely documented.

One proprietary part that is held close to the company in order to control how many airframes are built from the quantity of plans sold are the wing spar extrusions. But if the original company were somehow unable to provide these, I would expect the supplier of this extrusion to make arrangements for the completion of the airframes for the plans sets sold. Since this airplane is so completely documented and readily constructed from materials available from many sources, a plans holder would not be in nearly as dire a situation as some builders of composite machines have been - with much cash spent but still requiring many proprietary custom molded parts to finish.

Also, as of this writing, the company is in a tremendous growth stage with over 300 plans sets in the hands of builders, and as an exciting new design, a high percentage of these builders are actively in construction, providing plenty of orders to keep the company going.


Building a metal airplane consists of turning metal into noise and chips. Where a composite airplane may produce more dust and fumes, and impose temperature limitations on its build environment, working with metal can occur over a much wider range of temperatures. However, it will be loud. A Sonex build, however, will not be nearly as loud as any of the variety of solid-rivet designs out there. Since it is pull-rivet based (and the solids in the wing spar can be done without a rivet gun), the noise is limited largely to hammering, fly cutting, band sawing, and compressor noise.

As such, prepare an area tolerant of this noise, by acoustic separation and/or scheduling. Also, prepare yourself for such noise. Some people may be doing this without ear plugs, but I wear ear plugs and safety glasses pretty much the whole time I am working. May not be completely comfortable, but I'm used to it.

A few other things to prepare - a metal storage area, a power tools work area, a work table. If possible store the large sheets flat. I have a rack against the wall that the sheets lean into. This is more convenient than an under-table or behind-something setup. The power tools work area - since you will have a drill press, belt/disk sander, bandsaw, and bench grinder in use very often, a good area would provide outlets for them all, as well as bench space where they can all remain set up. The work table ideally is 4'x12' and leveled. Don't get too elaborate with the top - chipboard is fine. You will drill into this top thousands of times, and should expect to trash the table by the end of the project (or at least resurface it with another layer of chipboard). The point is to minimize $$$ in tooling like the table. Another handy tool for Sonex wing building are a pair of sawhorses. These don't need to be expensive or fancy, just level. (Well, not even level - if you can get them parallel in some other plane.) Add plenty of light, accessory outlets for the compressor, dremel-type hand-held electric grinding tool, and maybe a clock and radio, and that's it. You will be more satisfied with the project if this environment is secured first.

I also added a few things for my own work area - a completed parts storage area outside of the work area and raw stock storage area, and several old cabinets for storage of the non-airplane stuff that finds its way into a workshop. The airplane tools don't need much dedicated storage - a drawer for drill bits, but the rest of it works its way around the work table and power tool areas without ever needing to be "put away".


At the very beginning, shop for tools. These are covered elsewhere. But to start small, I would recommend the major power tools, less the air group. Skip the compressor, air drill and air rivet puller for now. With a "start small" strategy, these will be put off for over a year, and by then you probably will develop a very good idea of what will work for you.

I cover the basic tools on the Build2-1 page. This group consists of your choice of shears, measuring/marking devices, a few drill bits, files, and the "big power" group: drill press, belt/disk sander, bandsaw, and bench grinder with scotchbrite wheel.


From here, buy the plans. As I write this, they're $600USD. Attend their workshop if possible, or at least have someone show you the basics of marking/cutting and especially deburring.

First Parts: .025

From there, there are a few ways to go, all resulting in a year or more worth of Sonex parts that can easily be stored in a few boxes under the workbench. Starting with a sheet of .025, work wing ribs. From the scraps, do the wing rib gussets. And with the $20 brake from Harbor Freight (18" brake), get quite a few of the channel pieces out of the way.

Even if you later work from the prebent metal kit from Sonex (recommended for the control surfaces), having made a bunch of the short channel pieces won't require you to purchase an additional sheet of metal - with the prebent kit, the entire airplane is easily fit into 9 12'x4' sheets of .025 + 2 12'x4' sheets of .032. (check Sonex material planning guide for sheet quantities - numbers here may not be right)

Heavy metal

After getting into metal for a while on the first sheet of .025, then maybe progress into the thicker stuff: the .060, .090, and .190 sheet stock parts. These will take a while, and will require the addition of a bending tool. My bending tools of choice are brute force: a 4# hammer and big bench vise. Others have used various tools, but it seems like 6061 prefers to be pounded rather than pressed into a bend.

Angle stock

After a while of carving up the sheet stock, then maybe progress to the angle. Not counting the tail cone longerons & cockpit top & bottom angles, all of the angle stock will be cut down to pieces still easily stored in small boxes. There is a lot of angle stock carving in this project, and so far, Sonex has not offered any kind of pre-cut kit for the angle stock. So plans or "kit" it's the same job.

Big parts

This strategy page is starting to look a lot like a build guide, so suffice to say, by the time you get to carving out big parts or putting things together into assemblies, you will have plenty of experience for planning the work.

Following the strategy outlined above, you will be able to participate in the homebuilder community as a builder rather than "just looking" with minimal cash investment. You will be able to spend a lot of time working on parts, determining whether the effort is worthwhile, but without having a lot of parts and equipment sitting around which you may not use for years.

Also associated with this strategy, you will have 2 or 3 more years to refine your thoughts and choices regarding engines, radios, instruments, etc. And fellow builders as they fly their creations will pass on new tricks and ideas that can make your project even better. And industry as well as "the factory" will introduce new products and improvements that you won't be locked out of until the last possible moment.

You can take advantage of those few years of build to shop swap meets, fly ins, and the new/used parts markets to collect exactly the things that will work for your airplane. Even as people try things as straightforward as different wheels, tires, brakes, strobe systems/mounting schemes, and as bigger stuff develops - radios/instruments/engines - you can hang back and take it all in, knowing that as you are fabricating parts, you can adjust the final product.

I'm sure some builders out there know all this (probably most of them from previous experience). I did not find this strategy of building much emphasized at SunNFun / Oshkosh. But at these places, the kit manufacturers and vendors naturally want to sell product and "lock you in" to as much of their product as possible.

The Sonex design/company/marketing allows builders to create their airplanes in this "just in time" style of parts purchase and delivery. As yet they have not headed towards requiring customers to buy complete airframe kits with hugely inflated prices on individual components. I don't believe this is in their history or operating philosophy, and I would not expect them to steer far from a plans-built low-cost emphasis in the Sonex and follow-on airplanes. So in following the buy-as-needed strategy outlined above one is not penalized by much additional cost in purchasing items piecemeal from Sonex. I hope they choose to keep it that way, because the no-penalty buy-as-needed airframe is an uncommon (unique?) selling point for the Sonex, and its cost to performance ratio is unmatched at this time.

As a business, of course, they would prefer to sell as many items as possible, but application of just-in-time/slow-build strategy by Sonex builders may result in more completions and fewer abandoned projects. Also in favor of Sonex, we the builders are not giving up performance to gain the ability to buy just-in-time. Other similar/competitor designs that require a relatively huge (10x-15x-20x Sonex) initial investment for the most part have lower performance.