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Updated Sonex Installation Kits for Rotax 912 Series Engines.

Wed, 03 Dec 2025 01:39:32 GMT

A new development to support Sonex Aircraft's new Rotax engine mounts.

Sonex has felt the pressure from the aviation community for Rotax engine installations for many years.

In response, Sonex released their bed mount that would exclusively handle the 912 series of engines some years ago. While this engine mount underwent some changes over the years, Sonex recently released their new engine mounts for all aircraft they produce that have a propeller. This will encompass the Onex, Sonex, Waiex, Xenos, Highwing, both Legacy and B models. These new engine mounts, in new Sonex fashion, are white and will handle Rotax 912UL, 912ULS, 912iS, 914UL, 915iS and 916iS. Quite a leap and a bold new move for the company that has largely been powered by Aeroconversion's Aerovee and Aerovee Turbo (Sonex's very own power plant) and Jabiru's 2200 and 3300 engines since the very beginning.

The possibilities at this point are truly endless when going Rotax. With engine options ranging from 80-160hp, max service ceiling of 23,000 feet (though proven by Cub Crafters you can achieve 36,000 feet), 2-6 blade propeller configurations, all engines have a 2,000 hour TBO (except the 915iS at 1,200 hours), and fully broken in when delivered with warranty, from $18,000-$62,000. An overhauled Lycoming of similar power, more weight, and naturally aspirated, costs as much as Rotax's 916iS. A new Lycoming? Take a guess.. The choice is easy IF there's support options.

In recent months we have been developing a new installation kit for the 912 series engines that will work across the board with Sonex, Waiex, Xenos, and Onex. No matter Legacy or B model, conventional or tri-gear. While intended for the Sonex line of aircraft, this would also work for basically any aircraft utilizing a Rotax 912 series engine and suspension mount.

While not available (yet), we will be working on an installation kit variant for the turbo charged Rotax engines in the near future.

Featured above is Sonex employee Cris Nash's Sonex B with the 915iS in position to check fitment for future installation on the Sonex Highwing.

In our kit we're using genuine Rotax cooling parts, Toucan dual exhaust system ( not included, but available ), fiberglass components, weldments, bracketing, hoses, fittings, and other miscellaneous components. *Fuel system parts and wiring not included.

We designed and installed our new installation kit in a Sonex Onex. An engine installation package that doesn't have much real estate. We figured if it functioned in this airframe properly, it would be an easy and much roomier installation in other applications.

We have performed extensive ground testing by comparing warm up times, full power tethered pulls, and overall temperatures in 100 degree environments against other aircraft as well as our Rotax powered Sonex as the "control" aircraft. We have been very pleased with the results.

Recently we took to the skies and tested the Onex and its installation. While we expected it to perform well, frankly, we didn't expect to perform as well as it did. The flight went flawlessly. The plane is so well balanced, it would fly with or without a pilot (although we know that's not possible). It did not have a heavy wing, cooling issues, or any issues to speak of. Very uneventful which is what you strive for on a test flight.

Outside air temperature was 80 degrees Fahrenheit on the ground (2,120msl) and 30.17Hg. Climb rate of 1,300-1,400fpm sustained at 100mph. At 5,300 rpm our temperatures plateaued at 206 degrees Fahrenheit cylinder head temperature and 196 degrees Fahrenheit oil temperature. In terms of speed at 4,000msl the Onex indicates 165mph, and 180mph true. At max continuous of 5,500rpm, we indicated 170-175mph and 190-195mph true and showed temperatures of 210 degrees Fahrenheit cylinder head temperature and 210 degrees Fahrenheit oil temperature. Also no notable temperature increase in a slow speed, steep sustained climb to agitate the engine. While still subject to propeller pitch changes and diameter changes, these were impressive initial numbers. It also helped that this Onex is flush riveted to increase performance. In stall testing the Onex stalled clean at 40mph, and 37mph with flaps. You are also able to change your wing length by cutting down the wingtips. This will change things quite a bit in terms of climb and cruise depending on which route you decide to go.

While it has flown since, there has been no changes, issues, or hiccups it its performance and will continue its flight testing by its owner.

We're extremely pleased with the installation and we are officially offering the installation to the public.

There's many variables when installing a Rotax in an airframe and we can assist in supplying the components to make it a no brainer. Propeller, spinner, exhaust, engine mount, installation kit, we have it mapped out. Our install kit is being sold for $2,700 USD less shipping . Kits have been shipping out so if you would like to secure your position in line, please fill out our contact form with your aircraft model, items requested from the above , and we can assist you with a total cost and lead time.

It has been a long time coming and we are excited to grow the Sonex and Rotax union. We have more developments coming soon and we're excited to share them with the community.

Visit our Facebook page or Instagram for updates as things progress.

Lets talk... Spinners!

Sun, 01 Sep 2024 21:23:47 GMT

Every aircraft deserves a spinner.

Whether it's a tractor, pusher, VTOL, you name it, spinners have more purposes than most people imagine.

First thing that comes to mind is a spinner cleans up the look of a naked propeller hub. Most people just like the look, making a propeller look "finished". Almost like wearing a button up and topping it off with a tie. Although we all know a guy who just wants to rock out without a shirt on and that's great too.

Aerodynamics.

Not only does a spinner provide a finished look, aerodynamically they have a lot of advantages. A large portion of air surrounding the center of a propeller is very turbulent. In most cases a tractor configured aircraft is when you care most about a spinner. You have oncoming air engaging with the propeller, in which the hub and innermost areas of the propeller are essentially "beating" the air and creating turbulent, parasitic drag, that reduces overall efficiency of the hunk of whatever material you're trying to propel through the air. So by installing an appropriate spinner for your application, you can increase efficiency of a propeller, as well as your aircraft, by cleaning up that oncoming air and allowing it to flow through the propeller and over your aircraft, more effectively.

Cooling.

How you may ask? Let's talk about it.

Again, talking about tractor configurations, this can be a major deal. By not having a spinner, your aircraft can actually have less than optimal cooling. On most tractors you have air inlets on your cowling that are on either side of your propeller flange exit hole. This is so air comes in, passes over your cylinder heads, radiators, whatever or however you have your plane set up, and provides a large amount of air to keep your engine cool. Now in reference to the turbulent air that exists around the hub area of your propeller, this air has no rhyme or reason. If the air is getting beat up, it's being slowed down, decreasing its velocity, being ducted inefficiently, and causing your cooling system to work with a disadvantage. When that oncoming air is cleaned up by hitting the spinner, it is able to flow over it smoothly, it is then able to be ducted into those inlets at a greater velocity, therefore increasing your potential cooling.

Looks.

Sometimes a spinner is purely cosmetic. Especially on pusher type aircraft whether it's an ultralight, PPC, light sport aircraft like a Rans or Quicksilver, or something like an Air-Cam. You will likely see no advantages by putting a spinner on a pusher. But it will look good, and add that "cherry on top" depending on what kind of spinner you install.

Talks about spinners can go on and on. I'm not here to give an entire lesson, but a brief insight into what makes spinners, great.

When developing our Sonex cooling kits, the idea was to make everything compatible with the factory Sonex cowling. That being said, the exit hole out of the Sonex cowlings are very small. Typically around 6 inches. Being so small, there are no spinner companies that make a spinner that would be compatible with that size hole. While Sonex Aircraft makes a beautiful billet spinner/crush plate for their Sensenich propellers, those are specially made for just a Sensenich. We wanted a "conventional" spinner to offer our customers that would allow them to use other propellers on their Rotax powered Sonex's. So, our search began for something that would be a good fit for a Sonex fitted with a Rotax.

Rotax engines are an incredible pieces of machinery. You can run a variety of blade sizes, shapes, number or blades, weights, to achieve exactly what you want out of your aircraft. Whether it's a STOL aircraft, an aircraft built for speed, ultralight, or an in-between, there's quite literally hundreds of potential propeller combinations that can be run on a Rotax.

Having no luck finding a spinner manufacturer that could supply what we wanted, we pondered the next course of action.

Generally, when we need something, we don't stop at, "does it exist?" That generally spawns our next question, "Why not?" Which turns into, "let's make it."

Warp Drive Propellers has been in business since 1988 and if you've been in the light-aircraft world for an extended period of time, you have seen their propellers. They produce the strongest propeller in the light-aircraft market, while producing impressive performance numbers, and made in America. They're such a great propeller an unnamed French company began to produce their version of the same propeller. Having flown behind many different propellers, a Warp was a no brainer to us when it came to the prop we wanted on our Sonex and on most the aircraft at our facility. We wanted something with 3 blades, great appeal, that could make our plane perform great. The proof is, "in the pudding," so to speak with the numbers we consistently get out of their propellers.

Getting back to it..

With no spinner options, we began to design our own. Something clean, simple, and affordable.

We found a supplier for full carbon spinner cones, however we had to come up with our plate assemblies. In this case we designed our plates around 75, 100, and 101.6 mm bolt patterns and Warp Drive's propeller hubs. This plate replaces the crush plate all together for your propeller, eliminating some extra weight and the need to purchase a plate for your propeller. Because our spinners do not use screws around the circumference, we use a center shaft, and a single clamping bolt in the tip of the spinner to clamp it in place. Our plates are chamfered to match the profile of the spinner so when the fastening bolt is torqued, it seats the plate snuggly in the cone which does not allow the spinner to rotate or move and essentially uses your hub as a "key." Our design is much like the skull cap spinners many people may be familiar with. While this design is not new, it is a take on an already effective design that has been in use for decades. With the latest technologies, we're proud to produce a spinner made from some of the strongest basic construction materials available.

Having designed this spinner around a Warp for Sonex aircraft, we realize people may want to use them with different propellers and different aircraft.

These spinners are available in 2 or 3 blade configuration's for a Warp Drive HPL hub, or can be ordered cut/uncut to fit other propeller hubs and installed on an aircraft of your choice. In the future we will be offering different bolt patterns to cater to different engines/gearboxes.

We are offering them for $360 .

While spinners are not an especially hot topic, this is a fun product and exciting addition to our product line.

Release of Sonex/Waiex/Xenos A and B Model Rotax Installation Kits

Thu, 04 Jul 2024 21:01:14 GMT

As we begin releasing these kits, they are made to order. Realizing each aircraft builder does things a little bit different than the last, we can help, or direct you in the easiest and most effective direction to help you with your project.

Our basic cooling system assembly and scoop are priced at $1,350 .

Our complete kit; which is our cooling system assembly, scoop, oil thermostat, all fittings required, all hoses requires, all clamps required, oil can bracket, oil catch can, coolant reservoir, heat soak vents, and hardware, is priced at $1,950 .

Propeller, spinner, throttle system, and more miscellaneous items are available to complete your installation.

These assemblies (and additional optional components) are compatible with Sonex, Waiex, and Xenos, both A and B models. It requires the use of Sonex Aircraft's engine mount and attach bars, cowling side vents (And yes, the A model uses them too), Toucan exhaust system specially designed for Sonex, and Sonex's Rotax propeller spacer.

We HIGHLY recommend a horizontal split cowling and do not support the use of a vertical split cowling. From there the components are mount, plug, play.

Please contact us with the form at the bottom of the page, through our store, or feel free to give us a call.

We purchased our Sonex in May 2020 with the intention of installing a Rotax 912 series engine after noticing Sonex Aircraft had made a Rotax engine mount for their aircraft (They had been making them for a few years). With no models or instructions to base our installation off of (none in the U.S. and very few in other parts of the world), we initially had to shoot from the hip to install the engine. We installed a used Rotax in our Sonex. Used engines are readily available on the market, and even with over 1,000 hours, Rotax's will run 1,000 more without batting an eye.

Admittedly, the first install was not very pretty, but it was very functional. Initially we wanted to see if a Rotax powered Sonex was even a good fit, being that Sonex had already produced their aircraft with their AeroConversion's AeroVee (80hp) and AeroVee turbo (100hp), and the Jabiru 2200 (80hp) and Jabiru 3300 (120hp). After 7 months of hard work, our Rotax powered Sonex was ready for flight. In the beginning we had to overcome some hurdles with the initial engine mount design. After the release of a second generation attach-bar system (which had proven to be very successful) we were able to begin racking up hours in the Sonex. After flying off our Sonex's phase 1, we were able to fly to Airventure in 2021. We had a very exciting 3,500 mile round trip from Arizona to Wisconsin.

Being the only flying Rotax powered Sonex in the U.S., our Sonex was the "Ugly Duckling" of the fleet. Since it had been proven to be (arguably) the best performing Sonex configuration, we realized it needed a presentable face lift. We then got to work reimagining the image of a Sonex.

Sonex's are always seen with a fixed pitch, 2 blade propeller. Whether it was a Sensenich, Prince, etc, the norm was usually of one of those propellers and a small billet aluminum spinner/squash-plate. John Monnett, creator of Sonex Aircraft (and many more aircraft before that), had run with a timeless design variation that he had made decades before. While this was very attractive and Sonex's signature look, we wanted to do something a little different.

Our previous Jabiru 3300 equipped Sonex Legacy tri-gear.

In its first configuration, we had used the vertical split cowling. This cowling does not lend itself well to the Rotax because it has all its components on top of the engine for the most part, and carburetors on either side (depending on the model). So we purchased a horizontal split cowling from Sonex.

The only look that stayed was our 64", tapered tip, HPL 3 bladed propeller from Warp Drive. Warp Drive produces the strongest propellers in the light aircraft world, and one of the best performing propellers. Operating off of dirt and gravel (our Sonex does not live on pavement), Warp Drive was a no brainer. We fitted it up with a 9.75" carbon fiber spinner and the new cowling. We had to redesign our cooling system and exhaust so it wasn't hanging out in the open. Getting creative with some cooling designs that had been proven in the P-51 Mustang and Indy Car/F1 racing world, we created a cheap and effective way to keep the engine happy in all aspects of flight and in varying climates. After some math and theory, we began forming foam, fiberglass, a few reshaped pieces here and there, some intersection fairings, threw on some paint, and we had a modernized and fresh look for the Sonex.

Since then, Sonex chipped away at employee Cris Nash's Rotax 912 iS powered Sonex B, and Airventure hosted another successful One Week Wonder in 2022 featuring a Waiex B with a Rotax 912 iS. We were extremely fortunate to be asked to participate in this build, and be a small part of an incredible feat. Having been touched by thousands of hands and hundreds of man hours in just a week's time, the OWW was a testament that anything is possible when you get thousands of people together sharing such passion. My hat is off to the EAA and Sonex Aircraft especially. Everyone at Sonex (Mark, Cris, AJ, Tony, Tom, Steve, Nathan, Kerry, John, and pardon me if I forgot more people) worked tirelessly, with basically no sleep for a week, to make sure the Waiex made its way to show center for the everyone to see and experience. I cannot believe how hard they pushed themselves and it was an opportunity I will never forget.

Now that there's two flying Rotax powered Sonex's in the U.S. (EAA's and ours) and a third on the way (Cris's from Sonex) it was apparent the pairing was going to grow among the community. Having flown our Sonex to Airventure three times (2021, 2022, 2023) the proof of concept was there. After some pressure from a few folks, especially Bryan Walstrom (Experimental Aircraft Channel, thanks buddy) and a wonderful meeting with Sonex Aircraft, we began flight testing in 2024 to produce a simple firewall forward option for those wanting to install a Rotax 912 series engine in their Sonex. Essentially a basic copy of our current configuration with minimal changes/improvements, our package is very simple to install. The basic kit includes a cooling package the bolts up to the bottom of the engine mount to be fitted to the cowling and a scoop to be blistered in. The cooling "Scoop Assembly" seals to the bottom of the cowling from pressure and 1 screw. From there we offer everything needed to work in conjunction with Sonex Aircraft's supplied parts. Fittings hoses and clamps, oil can bracket, oil catch can, coolant reservoir, propeller, spinner, throttle system, and more miscellaneous items are available to complete your installation.

With different Rotax platforms available (914, 915, and 916) future installations of these engines are something we're looking into. While 100hp does the Sonex magnificently, we realize folks always want more. The current parts available only support the 912 series engines. Rotax produces the 912UL, 912ULS, 912iS, 914UL, 915iS and 916iS, ranging from 80hp-160hp with very minimal weight from model to model (125-190 pounds), burning 3.5-7 gallons an hour and 2,000 hour TBO's. It's a no brainer why people choose Rotax. While new Rotax engines are not cheap (cheap ain't good, good ain't cheap), the used market is a great outlet for engines that have plenty of life in them at a much lower cost. As previously mentioned, our Rotax is a used, nearly a 20 year old engine, and that doesn't bother us one bit.

We're looking forward to growing and working with the Sonex community. See you guys in the sky!