Frequently Asked Questions

Have a Question? You might find your answer here

The following are answers to some general Frequently Asked Questions (FAQ’s) about Sonex and AeroConversions products. If you have a question that is not covered on this page, send us an email sales@sonexaircraft.com or give us a call.

Terms & Conditions Subject Index:

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Sonex Aircraft FAQ Subject Index:

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General Questions:

Airframe:

Powerplant:

Carburetors:

Props:

Building:

Instruments:

FAA Requirements:


General Questions


Does Sonex Aircraft, LLC offer Demo Flights?

Factory Demo Rides are not offered for liability and prototype licensing reasons. There have been a number of excellent flight reports written by professional journalist test pilots for several aviation publications, which we feel offer much better insight to the aircraft’s overall handling and performance than a brief demo flight. There have also been numerous reports from builders that are flying posted to Builder Web Sites, Discussion Groups like SonexBuilders.net and hundreds of flying videos posted to YouTube. You can also use our searchable Sonex Builder Database to find a Sonex Aircraft pilot in your area. Many Sonex aircraft owners are more than willing to give rides to those who are seriously interested in building.

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Will Sonex Aircraft be at the Copperstate fly-in? Arlington fly-in? Sun ‘n Fun?

We are constantly evaluating which regional fly-ins and other events we should attend. Since we are headquartered in Oshkosh, you can be rest assured that we will always have a presence at EAA AirVenture Oshkosh every summer. We also frequently exhibit at Sun ‘n Fun. If we traveled to every event that occurred thorugh the year, however, we would never be at the factory getting parts out the door, and we evaluate event attendance choices very closely each year. Please visit our Company Events Calendar for the list of Fly-Ins and Events Sonex Aircraft, LLC will be attending each year.

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Airframe


B-Model Frequently Asked Questions

  1. I previously bought a Sonex, Waiex or Xenos Tail Kit, can it be used on a B-Model project? Yes! The tails are the same. Wings and fuselage are changed.
  2. I’m 6’4”, 220 lbs. Will I fit in the aircraft comfortably with a passenger? As always, your fit in any light aircraft very-much depends on your individual body geometry, your standards of comfort, and the size of your passengers. The new aircraft is very comfortable with a lot more room than the original Sonex, Waiex and Xenos, (read more) but we encourage everyone to try it on for size.
  3. Is the aircraft Sport Pilot eligible? Yes. B-Model aircraft powered by engines between 80-120 hp will definitely be Sport Pilot eligible, as are the original Sonex, Waiex and Xenos designs. Aircraft with more powerful engines installed may not meet the Sport Pilot maximum speed limitations.
  4. How does it fly? Just like the original Sonex, Waiex and Xenos!
  5. Are the B-Models Aerobatic?: Yes, they are approved for the Aerobatic Category when flown at 950 lbs gross weight or under, exactly like the legacy Sonex and Waiex (Xenos-B is approved for Aerobatic Category at 1,050 lbs, same as the legacy Xenos).
  6. Can I still put Sport Acro Ailerons on the B-Model Aircraft? Yes, the flap and aileron kit parts will stay the same for Sonex and Waiex, and the Sport Acro control surface optional instructions will remain in the plans.
  7. Where can I see a B-Model in-person? Come to our factory, or visit us at Sun ‘n Fun or EAA AirVenture Oshkosh!
  8. Can I scratch Build a B-Model? The B-Model versions of the Sonex, Waiex and Xenos are not available for scratch building. The original Sonex design is still available for scratch building, however, and we remain committed to serving the scratch building customer with that design.
  9. Can I get support to convert my Sonex, Waiex or Xenos project into a B-Model? Yes! Conversion Kits are available!
  10. Can the B-Model fuel tank, or enlarged instrument panel be used in my original model Sonex, Waiex or Xenos? No. The change in fuselage shape demands that these components be specially fitted for B-Model aircraft only. It is the changes to the B-Model fuselage that make these new components possible.
  11. Can I get a B-Model UL Power or Rotax motor mount for use on my original model Sonex, Waiex or Xenos? Not exactly. B-Model motor mounts are wider, and attach to the fuselage differently, but we now have Rotax engine mounts made specifically for Legacy Sonex, Waiex and Xenos! For UL Power engine installations, UL Power dealer Kaolin Aviation Services can provide UL Power mounts for your Legacy Sonex, Waiex, Xenos, and for Onex too!
  12. What kind of Firewall-Forward Support can I expect for UL Power or Rotax installation in my B-Model Kit? Sonex Aircraft is providing engine mounts for these engines, and a cowling in-which these engines will fit. Sonex customers have successfully used these engines in original model Sonex aircraft in the past, but the Sonex factory does not have a UL Power or Rotax installation its factory prototype fleet at this time. Beyond providing engine mount and cowling for B-Model kits, added installation support is not provided by Sonex Aircraft for these engines. There are, however, many support materials available for installation of AeroVee/AeroVee Turbo and Jabiru/CAMit 3300 engines in Sonex Aircraft. UL Power dealers in the U.S. have provided great support for customer installations through the years, and there are vast support resources available for Rotax engines, worldwide.


B-Model Conversion Kit FAQ’s

B-Model Conversion Kits are now available! Please Read the following important information:

  • No exchanges of legacy Sonex, Waiex or Xenos parts are available.
  • Builders will have to get their projects to a defined “starting point” for conversion. That may mean either building-up to the point where changes begin to take place, or removing parts to get “back” to the starting point of conversion changes. See our B-Model Conversion Process Description document for more information.
  • Depending upon a project’s status and condition, builders may need to fabricate or purchase replacement legacy (A-Model) parts at additional expense that are not part of the conversion kit. This will be more likely if builders need to remove parts to return to the conversion’s defined “starting point.”
  • No “partial conversions” will be supported — Sonex Aircraft can only offer support for construction as defined in the plans that are provided for conversion.
  • Wing conversion kits do not include new B-Model wing skins, as the conversion is most economically made by trimming existing wing skins. Builders may opt to purchase new B-Model wing skins at additional expense.
  • Builders must retain their original legacy plans set with their projects and legacy aircraft serial numbers will not be valid for building additional projects. Legacy aircraft that have been converted will receive a version of their original serial number that includes a conversion designator.
  • See our list of Legacy kit parts NOT used in B-Model Conversions (subject to change without notice).


Will I fit in the aircraft?

Check the published cockpit dimensions of Sonex Aircraft for yourself. We also highly recommend trying a Sonex Aircraft on before deciding if you fit. We have builders that are up to 6’6″ tall. Check-out our searchable Sonex Builder Database to find a Sonex aircraft in your area, or visit our factory for a tour, or to attend one of our upcoming events.

Cockpit Dimensions of Sonex-B, Waiex-B and Xenos-B:

  • Cockpit Width: 40 inches
  • Height from Seat Bottom to Canopy: 41 inches at each seat position (measured following seat back/body contours)
  • Height from Floor to Seat Front: 9 inches
  • Height from Floor to Instrument Panel: 21 inches
  • Distance from Rudder Pedals to Seat Back: 43 inches (measured straight from balls of feet with rudder pedals centered to seat front, then contoured along seat bottom to seat back)
  • Length of Seat Bottom: 24 inches (measured following seat bottom/body contours)
  • Length from Rudder Pedals to Front of Seat: 19 inches (measured straight from balls of feet with rudder pedals centered to seat front)

Cockpit Dimensions of the Onex:

The Onex features a 27 inch wide single-place cockpit, and has more headroom and leg room than the Sonex, Waiex and Xenos specs published above.

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How difficult is removing and re-installing Sonex Aircraft wings?

Wing Removal takes approx. 10 minutes and Installation takes 2 people approx. 15 minutes. The complete procedure is located on an instruction sheet that can be downloaded from the Instruction Sheets Page.

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How do the tail dragger versions of Sonex Aircraft compare to other tail wheel aircraft?

Tail Wheel Sonex Aircraft are just about the easiest tail wheel aircraft to fly. There are 3 things that make our tail draggers such simple aircraft to fly:

  1. The ability to fly slow: The Sonex Family of aircraft were designed from the ground up to fly slow! Approach on final with plenty of altitude to make the runway. Use full flaps on your approaches which gives you a spectacular descent rate and pull the throttle to idle. Slow your aircraft down to 55 to 60 mph on final approach. This reduces the amount of energy when you do touch down, so whether you’re 3 pointing or wheel landing, your Sonex or Waiex will be done flying and you’ll settle in like you’re hitting a pillow of air.
  2. Direct Steering: DON’T EVEN THINK of adding complicated, costly, and heavy differential brakes! Every Sonex aircraft pilot has raved about how great the direct steering feature is. Push the right rudder pedal- go right immediately. Push the left- go left immediately. A properly flown mission in a Sonex Aircraft will seldom, if ever, involve brakes. Hold brakes for initial start-up, Use them to hold short of the active runway, and the last time you should need them is when you’re pulling up to the hangar to stop for the day. Brake wear should be non-existent and in our opinion the tail dragger versions of our aircraft are the easiest to fly in their class.
  3. Titanium Landing Gear: These are a wonderful design feature of our Sonex, Waiex, and Xenos models, and meet the drop test standards from FAR Part 23. If you happen to flare too early and drop in hard, the gear dampens the shock considerably, will absorb the blow and allow you to settle in nicely.

As in any aircraft, if you really blow an approach and something doesn’t feel right, go around!

Note: when carrying passengers you will increase your sink rate considerably (A 200 lb passenger is a sizeable percentage of your gross weight..roughly 18% for a Sonex). Come in a bit hotter (perhaps 5mph or so) and when you have the runway made, start bleeding off your airspeed. You’ll also find that adding a touch of power just before touch down will yield some real nice “squeaker” landings.

Follow these tips and your landings will in short order become a non-event in your tail dragger Sonex Aircraft. The tips above are the same for the Xenos: just remove “flaps” from the above and insert “pull half spoilers and establish your sink rate..don’t touch them once you’re under 100 feet of altitude.”

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What is the speed/weight difference of Tri-Gear vs. Standard Gear Sonex aircraft?

Tri-Gear Sonex Aircraft are between 4-6 mph slower than a similarly-equipped tail dragger. While many have flown the tri-gear extensively on grass strips, we do not recommended the tri-gear for exceptionally rough-field use. Sonex aircraft are approximately 10-12 lbs heavier in the Tri-Gear configuration (+10 lbs for an AeroVee powered, Tri-Gear aircraft, +12 lbs for a Jabiru 3300 powered, Tri-Gear aircraft).

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What’s the difference between the Waiex and Sonex?

The tail configuration is the only difference between the Waiex and the Sonex. We built the Waiex using the “Y-tail” design simply because it looks cool! The unique “Y-tail” design flies exactly the same as the traditional-tailed Sonex. Don’t believe it? Read what our first customer Waiex pilot has to say, or read professional journalist test pilot Dan Johnson’s review of the Waiex for Kitplanes magazine. We recommend building whichever design you think looks better.

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How is the Xenos similar to the Sonex and Waiex?

Xenos shares the same cockpit and engine options as the Sonex. The fuselage is longer and it has a much larger tail to fly the longer wing.

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Can I use a Sonex/Waiex wing on a Xenos Fuselage? How about a Xenos Wing on a Sonex/Waiex Fuselage?

The answer to both questions is No. The Sonex/Waiex tails do not have enough tail volume for the larger Xenos wing and the Xenos tail is far too large for the Sonex and Waiex. Performance would be compromised in either scenario. It has been our design experience that when you try to do too many missions with a single design, you end up not doing either mission well. In this case, you’ll end up with a marginal motorglider and a marginal sportplane. Build the aircraft that you feel best fits your mission. Building one of each is a fantastic idea!

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Do you offer a Ballistic Parachute System?

We do not recommend a Ballistic Parachute System for use in any of our family of aircraft except the SubSonex Personal Jet. You may contact BRS for a design guide and their recommended installation.

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Do you have a “wet wing” option?

No. We feel the fuel capacity of Sonex Aircraft models is sufficient for the design philosophy (burn rate approx. 4 gallons/hour for Jabiru 2200 and 6 gallons/hour for 3300 Jabiru). Find out more.

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Powerplant


Do you have an electric starter system?

Yes. All approved engine options have electric start and full electrical systems.

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Is it possible to use an A-65 (180 lbs empty), 85 Continental, or Corvair?

The A-65, A-85, and Corvair are just too heavy for the Sonex. Again, the criteria for engine usage is 200 lbs or less (complete installed weight) between 80-120 hp.

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What is the AeroVee Overhaul Period?

The AeroVee Overhaul Period is 600-1400 hours. The more careful you are in putting it together, maintaining it properly, and running it in the green temperature ranges, the longer your overhaul period will be.

The really good news is that if you are on the lower end of the overhaul period range, the engine core parts are readily available at an extremely reasonable cost. A complete overhaul of an AeroVee Engine core will run in the $100-$500 range depending upon what needs to be replaced.

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Carburetors


Should I use an AeroInjector on my 2200 or 3300 Jabiru engine?

Absolutely. The overwhelming majority of the thousands of Sonex Fleet hours with the Jabiru 3300 Engines have been flown with either the AeroInjector (AeroCarb) or Ellison. The Sonex pilots using these combinations have seen remarkable performance. 150+ mph in cruise and 170+ mph top speed with the standard Sonex propellers. These alternative carbs allow Jabiru Engines to turn up higher and produce more power.

The AeroInjector exists (and has become a great option for many a homebuilder on a wide range of engines) because of the Bing Carburetor. We encountered many troubles and needless complications when installing Bing Carbs in our own factory Sonex Aircraft. While it has been claimed by Jabiru that “all of these issues have been fixed” we continue to see these surface as new builders complete and fly their Jabiru Powered Aircraft. Note that the most recent issues reported did have Bing Carbs with the “Economy Tuning Kits” installed.

With over 30 years of experience using throttle-body type carbs, we knew there was a better way and that we were just the design team that could introduce a better Carb for the Jabiru Engine. The result of our extensive R&D and flight testing is the AeroInjector.

The AeroInjector represents the better carburetor option for your Jabiru Engine in every measurable way, including but not limited to:

Some flight performance and test numbers to back up each of our claims:

While almost all of the Sonex Pilots with the 3300 Jabiru Engine are flying with an AeroInjector (including Sonex Prototype Serial Number 0001, Xenos Prototype Serial Number 0001, and Kerry Fores Serial Number 0009), there are some Sonex Pilots who insist on using the Bing carb. The reported performance and temperature data reported by these pilots has served as the control group as we compare them to those flying with the AeroInjector. This data was compiled using the same prop on the same airplane with the only difference being the Carburetors.

1. Increased flight performance:

All Jabiru Engines powered by alternative carbs perform better than the standard Bing. (Note that the Ellison Carb costs twice as much as the AeroInjector and still requires the use of a fuel pump.)

In an impromptu comparison flight, Kerry Fores in his AeroInjector (AeroCarb) equipped, 3300-powered tailwheel Sonex was able to catch up with a Bing-equipped 3300-powered tailwheel Sonex in a shallow climb and, once level, was able to easily pull away. Both aircraft have the same propeller. While this is “unscientific” data, it is the only head-to-head comparison we know of to date. While we’re confident the pilot of the other aircraft would not mind being identified, we will not identify him without his permission. This flight was witnessed from the cockpit by another builder, who is now flying his own AeroInjector equipped Jabiru 3300-powered Sonex.

2. Better Fuel Economy:

The AeroInjector provides better fuel economy because of two primary features. An infinitely adjustable main needle jet along with cockpit adjustable mixture control.

During initial tuning the fuel metering needle is set for optimum performance with the cockpit mixture control in the full-rich position, as detailed in the owner’s manual. Once in the air, the pilot can pull the mixture control until the engine just begins to run rough, then richen until it smooths out. This means the engine is always running at or near peak fuel efficiency. The AeroInjector saves between 3 and 4 gph vs. the standard Bing Carb in climb-out conditions and a little over 1 gph in an economy cruise over the Bing Carb. At $4 per gallon, the AeroInjector will pay for itself in much less than 100 hours of flying….then it’s just more money in your pocket.

On Kerry’s recent cross-country from Oshkosh to Sun and Fun and back (with his 3300 Jabiru powered Sonex) he had the opportunity to collect extended data on fuel consumption, particularly during the 1190 SM flight home which he was able to fly almost entirely at or near 8500 feet and 2950 rpm. With a fuel flow gauge fitted, which has proven extremely accurate over the past year of flying, cruise fuel burn rates ranged from 5.2 to 5.7 gph. Over the course of the entire flight fuel burn averaged 5.55 gph for time spent flying (fuel used/flight timer time), and 5.16 gph average for all time spent with the engine running (fuel used/hobbs meter time). Specifically, 88.76 gallons of gas were consumed, 17.2 hours were recorded on the Hobbs, and approximately 2400 miles were flown. The round trip flight included 8 stops (5 for fuel, 1 to wait for Lakeland airport to re-open after the airshow, and, of course, 1 each at arrival in Lakeland and back home in Oshkosh.

3. Lower Cylinder Head Temps:

Sonex Aircraft, LLC created its own laser-cut and pre-bent cooling baffle system for use with either the 2200 or 3300 Jabiru. We have been running these successfully in our factory aircraft with AeroInjectors with all temps well within the green. These baffles are available to any Jabiru Engine Owner, purchased through Sonex. We had two very recent reports of “high cylinder head temps with your laser-cut metal cooling baffles”. Both of these reports were from pilots who insisted on using the Bing Carb, who were running up to 350 degrees on the center and aft cylinders.

Kerry has been flying the aluminum cooling baffles on his aircraft for all of the airplane’s 400+ hours. He developed the aluminum baffles after struggling with the Jabiru-provided fiberglass baffles. The hottest cylinder is cylinder #6 which in cruise at 2950 rpm and with an OAT of 55 degrees would top off at 320 degrees, but would quickly drop below 295 at 2800 rpm or less. The next hottest cylinder was #5, which never went over 287 and averaged 278. It must be pointed out here that in local flights around the patch when the engine is not being operated almost continuously for over 8 hours, #6 cylinder seldom tops 300 degrees. Cooling for #6 cylinder, with the metal baffles, can be dramatically improved by replacing a large cowl seal over #6 cylinder with a piece of aluminum which will add two or three minutes to the time it takes to remove/install the baffle.

4. Lower Exhaust Gas Temps:

EGT is the primary indicator of optimum fuel consumption and power output. The AeroInjector puts that control in the pilot’s hand. By being able to pull the mixture lean in flight, power output is optimized and fuel consumption minimized. Without this control a pilot is at the mercy of a properly tuned Bing carb, a properly profiled needle, and the ill effects that come when the carburetor is no longer operating as efficiently as “new”. The actual temperature to which you can lean changes from day to day, but with the AeroInjector the range is about 1285 degrees to 1425 degrees before engine performance diminishes from lack of fuel.

The Bottom line is that the pilot is in control of this most critical component of engine operation whether operating at full throttle in a zoom climb or cruising at altitude.

5. Lower Oil Temps:

Due to lower cylinder head and overall lower engine temperatures by running with the AeroInjector, oil temps have been observed 20 to 30 degrees lower than those running with the Bing. We also observed the elimination of the big heat-generating muffler and instead created our own straight-pipe exhaust system on the Sonex, which was also one of the reasons for these lower oil temps.

Oil temps with the Sonex/Jabiru 3300 oil cooler installation ranged from a low of 168 degrees on Kerry’s flight to Florida, to a high of 185 degrees. Oil pressure in cruising flight ranged from 49 psi to 54 psi. On a hot day of playing around the oil temperature will climb to 220 degrees, but will fall off quickly when flight attitude is stabilized or the throttle is brought back from the firewall. When the temperature falls below 40 degrees, the air inlet for the oil cooler can be closed off entirely. Oil temps should be allowed to climb high enough to burn out the moisture in the engine, but not so high as to impede proper cooling and lubrication.

6. Simpler Installation due to the elimination of the fuel pump. Also eliminates vapor lock:

Anytime we can eliminate another mechanical system on an aircraft that can fail, we jump at the chance. The variable fuel pressures delivered by the fuel pump can also result in vapor lock, which is eliminated when the AeroInjector is used.

7. Simpler Installation due to built-in control cable mounts:

Those of you who have accomplished a Bing Carb installation know exactly what we’re talking about. Most Bing Carb installers fashion their own custom brackets and modify the Bing Carb throttle control to make the installation somewhat workable. The AeroInjector has a built-in Throttle Cable Clamp along with Mixture Mount, greatly simplifying your cable routing. The new “pull-type” installation now available on the AeroInjector offers an even cleaner and simpler installation along with more flexibility in control cable routing.

8. Allows for Aerobatics:

Because the AeroInjector lacks a float bowl and delivers fuel largely based on the suction of the engine, it is the perfect carb for those intending to do positive G Aerobatics. (A reverse fuel and oil system would have to be added to do longer duration inverted flight).

9. Simpler Starting (no primer or choke required):

A properly tuned AeroInjector will have your Jabiru starting on the first or second blade every time. We have never installed a primer and have never required a choke.

10. Impervious to carb ice:

Due to its design with no venturi and no butterfly, no factory AeroInjector installations have ever used carb heat. There has also never been a documented case of carb ice in any AeroInjector installation or any of the carbs in the same family including the Lake Injector and POSA carbs which are well into the tens of thousands of flight hours.

11. Lower Maintenance and Less Prone to Clogging:

Due to its minimal part count and simple design, the AeroInjector represents a quantum leap in reduced maintenance compared to the Bing Carb. Also due to the AeroInjector’s clean, straight-through fuel orifice and as long as standard aircraft fuel filtration is used, fuel clogging due to debris or water in the fuel system are non-existent.

12. Weight Savings:

The AeroInjector itself weighs just over one pound less than the Bing Carb. There is additional weight savings in the simpler installation of approx 3 or 4 lbs with the deletion of the fuel pump (for those aircraft that can use gravity feed), carb heat box, and associated scat hose and clamps.

The AeroInjector has emerged as the preferred choice for a wide range of engine types. Hundreds of AeroInjectors & AeroCarbs are currently being flown on Continentals, Lycomings, VW’s, Subaru’s, Corvairs, and virtually every other aircraft powerplant under 160 hp. The AeroInjector is for those who love simplicity and want to maximize the performance of their Jabiru Engine.

There is an excellent article on this subject: “The $35 Hamburger” by Kerry Fores (Fuel Burn on the AeroCarb-equipped 3300 Jabiru)

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What are the Fuel Burn rates and Performance with Standard Sonex Props?

The AeroInjector optimizes fuel burn for all three of the factory-supported engine options. With the 80hp engines (2200 Jabiru and 2180 AeroVee), we see a fuel burn of under 4 gph at 3000rpm. With the 120hp Jabiru Engine, we see fule burn rates of under 6 gph also at 3000 rpm. Read “The $35 Hamburger” for more information about the AeroInjector (AeroCarb) on the Jabiru 3300 powered Sonex.

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How does the use of the AeroInjector affect my Jabiru Engine Warranty?

Sonex Aircraft knows of no instance where a warranty claim has been denied because an AeroInjector has been fitted. To our knowledge, they have honored all engine warranty issues brought to their attention regardless of AeroInjector use. That said, if you “cook” your Jabiru Engine using an AeroInjector because you weren’t monitoring temperatures or didn’t have your AeroInjector tuned properly, then you will be paying for the repairs to your engine. Follow the detailed instructions in your AeroInjector Owners Manual and your Jabiru engine will have better performance, will run cool, and will burn less fuel, virtually eliminating carburetor maintenance to boot.

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The Bing Carb has been flying on Jabiru Engines all over the world for years. Why are you trying to reinvent the wheel by going to an AeroInjector?

Our best comparison to the modifications we make to the Jabiru Engine to make it better is the after-market Auto Market. There are many thousands of catalog and web site pages filled with different versions of carbs, manifolds, exhausts, fuel injectors, ignition systems, and misc accessories for just about every automobile on the road. These different versions make various claims as to increased performance, weight savings, better cooling, and better fuel economy just to name a few…. All the same things that the AeroInjector offers Jabiru Engine Pilots. Our question is, once you learn all of the advantages the AeroInjector brings with it, why would anyone fly with a Bing Carburetor?

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Props


How do I select a propeller for my Sonex Aircraft?

We have gone through a thorough and scientific testing process with a wide range of propellers for all Sonex Aircraft Models. We work most closely with Sensenich Propellers and have flown many different models and sizes of their fixed-pitch wood and wood-core composite coated propellers. The recommended propellers are listed on the Propeller Page on this site.

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How do I select a propeller for my direct-drive AeroVee powered Aircraft (other than Sonex, Aircraft)?

There are a handful of people in the world that understand the proper design and selection of propellers for different engine and airframe combinations. We have put our trust in Sensenich and their design engineers, who are among the leading experts in their field. They have generated a database of recommended propellers playing to the strength of the Direct-Drive Jabiru 2200 Engines and other direct drive VW Engine conversions. For a first prop iteration on the AeroVee, we have simply made Left-turning version of the Jabiru 2200 propellers. It’s a great way to get close on the very first prop.

There is no question higher propeller efficiencies can be reached using a reduction drive. However, reduction drives come at a cost to complexity and weight. Instead, keep the weight off and design the prop to turn up higher.

Our Xenos is impressive to watch climb out using the purpose-designed 56-inch Sensenich prop. A similar propeller would be recommended for slower high-wing aircraft where optimizing climb performance is the goal.

We are very confident in the AeroVee and feel it will continue to take marketshare away from the more expensive and complex alternatives without sacrificing performance.

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Is it possible to use an adjustable pitch prop?

To date, we have not found a ground- or air-adjustable propeller that is appropriate to use with the direct-drive Jabirus and AeroVee. We have instead focused all of our development focus on light-weight, simple, inexpensive, reliable and high-performance two-blade fixed-pitch wood or wood-core, composite-clad prop. View or Propellers Page for more information.

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What is Sonex Aircraft’s approach to propeller selection and how does Sonex Aircraft measure and compare performance with the various propeller manufacturers?

After 30 years of testing hundreds of different propellers in a quest to achieve maximum performance out of a wide range of airframe and engine combinations, there are many things we have learned.

Generally, performance increases will happen in very small increments when using different propeller makes and models. In rare cases, you can see huge performance increases when the first prop is totally “out of the performance box”. With the preferred prop manufacturer we have been working with, Sensenich, they have been very close to an optimized prop with their first design.

When measuring performance, it is very important to do an “apples vs. apples” comparison. This means flying the props you wish to compare in identical atmospheric conditions flown on a triangular course to account for wind speed and direction. Sonex Aircraft, LLC has developed a very large database of prop performance over the past 10 years for all 3 of our standard engine options…not only from our own prop tests (approx. 20 different propellers on our factory aircraft), but also from flying customer aircraft.

We have made no secret that we prefer to pitch props on the climb side of things, which will give you maximum power when you need it most-on climb-out…especially if you’re operating out of a short, grass strip with obstacles. It does not hurt to allow direct drive engines like the Jabiru or AeroVee to “turn up” at Wide Open Throttle (WOT), so in most cases the climb props can obtain the same top speeds as cruise props, just at a higher rpm and slightly higher fuel burn. It is therefore very important to record performance data at various tachometer settings when comparing two or three different propellers to each other.

Sonex Aircraft, LLC will continue to test a wide range of props to continue the quest for optimized performance. Please refer to the SonexAircraft.com Propeller Page for the most current recommended Propeller List.

Sonex Aircraft, LLC has an excellent reputation for publishing conservative and realistic performance numbers. We feel this is of the utmost importance when customers and potential customers are looking at the Sonex, Waiex, or Xenos as their next project.

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Building


What is the estimated Build Time?

Using our basic Complete Airframe Kits, 700-1,000 hours is the average build time for most of our piston models, and we have seen build times as low as 500 hours. Completion of the Xenos Complete Airframe Kit should take between 1,000-1,200 hours on average. Our Quick Build Kits bring build times down to the range of 300-500 hours or less! These build time estimates, like all build time estimates, will vary with things like build experience, life distractions, your ability to complete long-term projects and other factors.

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How much Shop Space is required to build a Sonex Aircraft?

Speaking in terms of absolute minimums, the minimum shop size to build most of our models is 6 feet by 16 feet. 10 feet by 30 feet would be the absolute minimum space required to build the Xenos.

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Can I purchase Sonex Aircraft Kits in Sections?

Yes! Sonex aircraft can now be built using Sub-Kits, Complete Airframe Kits, or Quick Build Kits.

By far, the most economical way to kit build is with the Complete Airframe Kit, which offers more bulk purchase discounts, and reduces shipping costs to one consolidated shipment.

We highly recommend starting your kit aircraft savings account now in order to purchase the whole kit at one time. This saves Sonex Aircraft builders a significant amount of time and money. Remember that financing is available for most Sonex Aircraft models.

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I’m confused by your Sub-Kit pricing. Its seems as-though Sub-Kit builders are unfairly required to pay a penalty of several thousands of dollars vs. Complete Airframe Kit builders.

Our Sub-Kit pricing does not represent a penalty of any kind to our customers. Conversely, our Complete Airframe Kits represent an additional opportunity for better savings via bulk purchase discounting, which is something our competitors do not offer on their complete kit packages.

From Day One, our Complete Airframe Kits were configured and priced to be the market’s low-cost leader. You would be hard-pressed to find more value for dollar in any other kit aircraft package. We are able to do this via bulk kit-set purchasing from our vendors, bulk packaging and bulk purchase discounting of the Complete Airframe Kit package to our customers. Very similar to the economics driving a “2 for the price of 1” special in your local grocery store.

For this reason, we have always resisted selling the aircraft in Sub-Kits as other manufacturers traditionally have, because we knew we would not be able to offer pricing as low as we can for the Complete Airframe Kit package. Due to consumer demand, we finally made the decision to offer Sub-Kits early in 2009. Just like making two separate, individual purchases of “2 for the price of 1” items in your grocery store, breaking our Complete Airframe Kit package up into smaller Sub-Kit packages reduces the opportunities for bulk purchase discounting.

Sub-Kit builders still have an opportunity to save more with bulk purchases: For those who are interested in using the Tail Kit to get comfortable with the project before committing to the entire project, they can start with the Tail Kit, and decide to buy all remaining Sub-Kits in a single purchase with our Sonex Aircraft Kit-Minus-Tail Packages!

For those who wish to spread Sub-Kit purchases out over-time, the price differential is still very competitive with the typical amount of interest paid on financing of a Complete Airframe Kit purchase.

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How much money can be saved by scratch-building instead of building from a kit?

Only the original, Legacy (A-Model) Sonex plans are available for scratch building. In the very roughest of numbers, a scratch-built Sonex Airframe will cost you about $9,000 to $10,000* in materials IF you do all your welding, metal forming, layouts, etc. That compares directly to the cost of a Complete Airframe Kit.

The reality is that once they do the analysis, most builders are going with the Complete Airframe Kit. In our opinion, you’ll have well less than 1/2 the build time along with some other great benefits…laser-cut skins and factory welded parts make for an extremely accurate build experience.

Many scratch builders decide to pick-and-choose certain kit components to purchase from Sonex for portions of the project they do not wish to tackle. A list of all of the individual items available for purchase for the scratch builder can be found on our Scratch Building page.

If you are considering scratch building as a way to better afford a Complete Airframe Kit by purchasing all the components individually over time, you are guaranteed to spend much more than the Airframe Kit price by the time your aircraft is completed (read “Can I purchase the Sonex Kit in Sections?” above). The only way to glean any cost savings by scratch building is to fabricate the majority of the aircraft parts yourself from raw materials.

In summary, people that elect to truly scratch-build the Sonex should be doing so for the added challenge and educational value that scratch building offers, not as a way to save money.

*Note that any Complete Airframe Kit price increases that occur are mostly tied with material cost increases, so the proportional relationship between the quoted material cost and kit prices will remain very much the same as kit prices increase over the years.

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With the stainless steel rivets against the aluminum skin, isn’t there a galvanic corrosion problem?

No. We have been using this combination since 1972 and have not experienced galvanic corrosion.

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Can regular (1/8″ diameter) bucked rivets be substituted for the blind (1/8″) rivets where both sides are accessible?

Yes. However there are areas, particularly in the leading edge and closed control surfaces, where bucked rivets cannot be used.

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Would it be possible to get some of the CAD files of certain plans pages, parts or assemblies?

No. For proprietary reasons, the plans are only available in printed form, and control drawing files for individual parts and assemblies are not available.

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I’m considering the purchase of a second-hand kit or maybe even a completed, flying aircraft. Does Sonex get involved with used sales? Do you have any advice for me?

Sonex Aircraft does not keep track of used kits and aircraft for sale, nor do we get involved in second-hand transactions or the inspection of kits and aircraft for sale.

We do support owners of second-hand kits and aircraft once they are properly registered with us, per our Terms & Conditions for ownership transfer.

To make sure you are truly getting a good deal on the second-hand purchase of a Sonex Aircraft kit or completed aircraft, read Sonex Aircraft’s guidance on Buying New vs. Used kits and aircraft.

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Instruments


Is there room to install GPS-based moving map displays and MFD’s? How about a transponder? How about a complete IFR panel?

You can install any instrumentation you wish in your Sonex Aircraft. Just keep track of the overall weight of the various packages and watch the power requirements. While the heart of our aircraft is in a fun day VFR mission, they do enjoy very good cross country capability, especially due to their outstanding fuel economy.

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What do you consider the “standard instrument package” for Sonex aircraft?

In most cases, we have installed the MGL Avionics series of instruments in our factory prototypes. You can learn more about these instruments through the Instruments Page.

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FAA Requirements


How do I show that my Sonex Aircraft complies with the FAA’s “51 Percent” Rule?

Showing Compliance with the FAA’s “Major Portion” or “51 Percent” rules for Experimental Amateur-Built aircraft certification is now easier than ever under the National Kit Evaluation Team system. Sonex is proud to have been a partner with FAA and industry in developing the NKET system.

To learn more and download FAA National Kit Evaluation Team checklists for Sonex Aircraft, learn about EAA’s Amateur-Built Aircraft Certification Kit, and find tips about registration of the Xenos Motorglider, go to our Aircraft Certification page.

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How do I register my aircraft for flight under the Sport Pilot rule?

All Sonex Aircraft builders will register their aircraft as Experimental/Amateur Built Aircraft. You can register your aircraft under these existing rules and fly it as a Sport Pilot because it’s performance and specifications fit within the Sport Pilot envelope. Registering as Experimental Amateur Built allows you to obtain a Repairman’s Certificate for your aircraft and perform all of your own maintenance without attending specialized LSA maintenance classes. Sonex Aircraft has no vehicle available to builders for E-LSA registration.

For information about FAA National Kit Evaluation Team checklists for Sonex Aircraft, EAA’s Amateur-Built Aircraft Certification Kit, and tips about registration of the Xenos Motorglider, go to our Aircraft Certification page.

For More information about Sonex Aircraft and Sport Pilot, view our Sport Pilot page.

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What are the annual inspection requirements for homebuilt aircraft?

To maintain an aircraft’s airworthiness, an Annual Condition Inspection must be performed and logged in the aircraft’s airframe logbook. The detail and scope of this inspection for aircraft registered in the United States of America is outlined by the FAA in FAR 43, Appendix D.

This appendix is available on the FAA’s website at http://www.faa.gov/regulations_policies/. Follow the links on this site to FAR 43, Appendix D.

A more user-friendly version of the this FAR is available to EAA members in the Homebuilder’s section of their website, www.eaa.org. The EAA’s inspection document is formatted in an easy-to-use checklist format.

Your particular aircraft may require additional inspections depending on installed equipment (Transponders, VOR’s, etc).

It is your responsibility to maintain your aircraft as prescribed by the governing authority of your country. Failure to complete and properly document each annual condition inspection can jeopardize the safety of your aircraft, your insurance, and your piloting privileges.

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Does the Xenos meet the criteria for Powered Gliders?

Yes. The Xenos does meet the criteria set-forth by FAA Advisory Circular AC 21-17a defining Powered Gliders. The Xenos can be registered as an Experimental/Amateur Built aircraft and flown by pilots who hold a glider license with a self-launch glider endorsement. The Xenos can also be flown under both the Sport Pilot, and Private Pilot regulations. For more information about the definition of a Powered Glider, and the applicability of the Xenos, read our Motorglider Definition page.

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