Zenith CH 650 vs. Sonex: "Competitive Comparison"

The following is an unusual post because I don't normally comment negatively about competitors.  Competition is good for any industry, forcing us to be innovative and efficient, and there is a place and market for many different airplane designs (and the companies that manufacture them): The current issue of Kitplanes magazine (December 2011) contains the annual Buyer's Guide with 316 different kit aircraft listed (from nearly as many manufacturers)!

The letter that follows is from a CH 650 builder and is in direct response to a Sonex marketing brochure found on the company's website under "Competitive Comparisons," so I think we can all agree that it's fair game to share this response.

Here's the Sonex brochure. Click image for a larger view.  Note that the highlighted (yellow) and hand-written text is part of the original document: Download the original sales brochure.

Now here's the response letter.  It's a little bit long but does a good job of covering the main issues:

Back when I was shopping for a kit, I compared similar LSA class airplanes, much like Sonex summarizes in its sales brochure called “Competitive Comparisons” (below).  Looking back on this comparison after-the-fact reinforces the excellent decision I made in purchasing my Zenith kit.   Like a lot of sales pitches, many of the important points are not even addressed in the Sonex brochure.

The RV-12, Zenith CH650 and Rans S-19 have similar performance because they were designed for the LSA category and have similar weights (1,320 LSA limit) and wing areas (around 130 sq.ft.).  With its lower weight and much smaller wing, evidently the Sonex was not (it was designed before Sport Pilot?) and has less load carrying ability.

It’s interesting that Sonex promotes speed (150 - 170 mph TAS true airspeed at altitude) and low-cost cross-country capability, but no Sonex owners I’ve met take their planes anywhere - these planes don’t seem to be used for cross-country at all (because of the engine and cabin size?).  According to the Sonex website, they don’t evern fly their  planes to attend airshows (apart from AirVenture which is at their home airport)...

I was always told never to buy an airplane without first flying it.  Well, Sonex doesn’t offer any demo flights because of “liability and prototype licensing reasons”?!? I’m not aware of any manufacturer with these problems (or excuses) and wonder how builders can get insurance in something they’ve never been able to fly...  Oh, well, I probably wouldn’t fit in anyway.  I’m about average size (at just under 6 feet and slightly over 200 pounds) and doubt two of us would fit comfortably.  (By contrast, when I first visited Zenith last year I was offered a demo flight without even asking for one and I’ve been hooked ever since!)  The Sonex website invites you to read flight reports instead of a demo flight... seriously?  The website also advises to find a local owner for a flight demo: When I tried that I couldn’t find anyone willing to take me up... due to my “large” size!

Of course, the main topic missing in this Sonex comparison chart is the actual kit, and that‘s where Sonex lags way behind the RV, Zenith and Rans products. With its kit Sonex has not kept up with the other three manufacturers which use precision CNC cutting and drilling and match hole technology (which is truly awesome for the builder!)  The Sonex folks have not invested in a technology that benefits builders tremendously (instead Sonex seems to “invest” in projects like putting a small jet on their plane - a PR stunt in my opinion...)  Talking to actual builders I heard an earful about Sonex factory support, especially lack of available tech support and weird hours (the support phone line is only open a few hours per day while the sales phone line is always open?).  Sonex builders are largely on their own (mainly getting needed assistance from each other).  In contrast, you guys at Zenith have been great (and patient) with my newbie questions, and I also have easy access to your test pilot and aeronautical engineer!  How cool is that?

While Sonex keeps emphasizing the low price of their design my calculations show different:
The basic Sonex kit sells for $14,500 but that’s without the finished wing spars (which I definitely want the factory to finish), needed hardware (rivets, AN nuts and bolts, etc. that the other kits include), tricycle gear (sold as an option?).  Add all these “options” in (that are standard with the competition) and the price is over $20,000 for the Sonex airframe kit!  IMHO, the Sonex ends up costing no less than my Zenith and the quality and level of completion of the kit and support is poor compared to Rans, Zenith or RV.  My CH 650 kit (airframe and finishing kit plus a couple options) cost me just under $20,000 and the quality of the parts and assembly manuals is excellent, especially for the price.

Engine:  The standard engine for the Sonex is the AeroVee - a “VW Beetle” based auto conversion rated at 80 hp (at a high 3400 rpm) that is sold as a Conversion Kit and needs to be assembled.  With the recommended options the price for the VW engine kit is about $8,500 - plus assembly!  For my CH 650, I’m planning to install a Continental O-200 (100-hp at 2750 rpm).  I bought a mid-time used O-200-A model for less than the AeroVee engine kit and am in the process of upgrading it with a lightweight starter and alternator.  If I have money available I may look at installing a new light-weight aircraft engine like the UL Power, Jabiru or maybe even the Rotax - I like the fact I can sell the used Continental probably for more money than I have in it, and Zenith is the only manufacturer of the group that supports this popular engine (I learned to fly in a C150 with an O-200 in the early 80's and my airport mechanic still recommends it).  Because Sonex and AeroVee are one and the same, it looks like they’ve built an airplane for the VW engine and they have little interest in supporting other light aircraft engines such as the O-200, Rotax or even the new UL Power engine. They do support the Jabiru engines (but I hear many stories about them over-heating).

The low Sonex price estimates include $2000 for the instrument panel, including a handheld radio!  Obviously these guys don’t take their planes anywhere.   I plan to use a Dynon glass panel display and Garmin radio, and should be in the air for less than the $42,814 that the Sonex ad estimates (I figure I’ll have about $30k in my CH 650 project with the O200 engine installed, but I'll need to add instruments, seats and paint). Cost is one of the reasons I’m building the Zenith and not a Rans or RV, but I also love the look of the new CH650 and the support for the Continental motor.

Additional points:  I don’t like having the fuel stored in the fuselage, nor the small size on the Sonex tank (the RV-12 has the gas in the fuselage also) and I like your welded aluminum fuel tanks (in the wings).  Forty pounds is OK for most outings, but where do you put it in the Sonex?  (I just love the wing baggage lockers on the CH 650 - that just makes a lot of sense and will keep my wife happy on cross-country trips).

The Sonex brochure states that “the strength is there and has been proven. Over stressed, over gross, over speed, it's seen it all and survived.”  Wow!  It’s hard to imagine a manufacturer recommending customers to “over stress” the aircraft... why ?!?  The CH 650, S-19 and RV-12 have all been designed and tested to meet the LSA standards, but surprisingly the Sonex has not.  Based on my years following these designs I can only conclude that the “CH 650 B” is the most proven and tested model of the bunch - what other LSA-class plane has been thoroughly tested not only by the designer (and outside consultants) but also by the FAA and NTSB? (And I will plan to fly the plane within design limits and not to “over stress” or “over speed” it).

All in all I am still thrilled to be building a Zenith.  Comparison charts like the attached prove that I've made the right choice!  Thanks again for a great product and for supporting us builders like you do.

While this is a flattering letter (hey, maybe that's the reason I'm posting it here!), I do think it addresses some important issues and competitive points, and adds needed perspective to this particular "Competitive Comparisons" sales brochure.


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Comment by Joe Scheibinger on November 30, 2012 at 8:01pm

This is a great letter Sebastien. Here are the reasons why I picked the Zenith over the Sonex. I am lucky enough to live in Oshkosh where the Sonex is manufactured. I know John personally, and even live on the same street as John! I did consider the Sonex before I bought my Zenith. The wing spar on the Sonex is made from extruded aluminum and the die for it is the property of Sonex! If Sonex ever was forced out of business there would never be a possibility of replacing the wing spar in case of an accident or rebuild. That is completely unacceptable. I have no idea why it was designed that way. For a larger person, the Sonex is a single place airplane, not just for weight, but because of the cramped cockpit. In fact you can build a Sonex as a single place aerobatic plane and sit in the middle! It makes a perfect single place airplane. Having the fuel tank in the cockpit is unacceptable to me. I hated that most of all after owning an Ercoupe. The Sonex Designer who I hold in high esteem with his knowledge of aircraft design, takes a very hard line to builders who deviate from the plans in any way. If you decide to install an engine other than his version of the VW or the Jab, you are shunned from the Sonex community. While EAA was fighting to keep Ethanol out of aircraft fuel tanks, Sonex took a grant from the ethanol community and used it to advertise a "green" airplane, a slap in the face to EAA. If you are going to lay out tens of thousands of dollars for a homebuilt aircraft you want to make sure you can take it anywhere in comfort and style. Both are lacking in the Sonex. Both aircraft are great little planes! but the Sonex is a novelty in comparison. The Sonex has only 2 engine options. One is considered under powered my most people, and one overpowered with cooling problems. I lost count on how many different engines work just fine on a Zenith! The resale value on the Zenith holds up much better than a Sonex. Most of the flying 650's I have seen advertised are selling for about 120% of kit price. Just ask yourself, when my plane is finished who would I like to take for a ride! That decision is a lot harder in a Sonex!

Comment by Alberto Martin on August 5, 2012 at 4:57pm

I´ve a friend that has a Sonex, there are less than 15-20 in Spain, and he is really happy with it. One exception, the Aerovee engine. He had had many cooling problems, vapour locks, etc. He allways tells me "if I had money I would have chosen the jabiru 3300 like your XL" ....

Comment by Jake Reyna on March 28, 2012 at 8:49am

Just stumbled across this blog. When I was shopping for a kit in 2005, I looked at the XL, Sonex and Kitfox. The biggest flaw with the Sonex, IMO, was cabin width, 40", but that means 38". I have broad shoulders 24", weigh 190 pounds. Since I'm building an airplane, why do I want to be packed like tuna? If I wanted to carry a passenger, I'm limited to someone that is 14" wide. The Sonex is fast with the Jabiru 3300, but I'd be flying alone, what's the point of not sharing?

Since that time 2005, the RV-12 and S-19 have come along, both nice airplane, but bang for the buck, you're better off with a 650. More engine options and the possibility of being 100 pounds lighter, if you focus on keeping it light.

Comment by Dan Sherburn on November 13, 2011 at 8:02am

The response probably echoes my research precisely. When looking at kits (obviously my 750 has a different mission than does a Sonex) I based my ultimate decission on:

    * manufacturer offering  test flights

    * availability (and general attitude) of factory sales and support mechanisms

    * engine choice (big one). I like the "common as dirt" O-200

    * completeness of kit. Kit prices can be misleading if you don't add up what's not included (hardware, etc).


Comment by Chris Aysen on November 10, 2011 at 9:17am

When I was engine searching I had considered the AeroVee until another 701 builder before me mounted one on his plane and was completely dissatisfied with it's apparent lack of power. Some of the post above confirm that. With that said I don't think Sonex can compare itself to Zenith as far as aerodynamic design goes. The Sonex is over 200 lbs lighter in gross, narrower, and built for low G aerobatics. The 650 serves a different purpose; more of a cross-country traveling in style plane. The only reason I see that they (Sonex) would make a comparison is because of the success Zenith is having. I'm not knocking the Sonex because I had considered building one myself. I have seen some videos on the Sonex that are impressive; even with the AeroVee. But in my opinion it does not compare to the 650; they are just TOO different planes.... I personally believe the reason Sonex does not support other engines is because of inherent cost. They have designed an engine (AeroVee) that takes their airframe designs well enough into the aerodynamic envelope that they feel they do not need to support other engine choices. In the same token, in MY opinion, Zenith has achieved enough success that they feel they are able to support a variety engines without it affecting negatively on their business. Sonex would probably much better off to not compare the Sonex or any of its other models to the 650.

Comment by J. Davis on November 9, 2011 at 9:38am

I, too, have built (and am currently flying) a Sonex, and am currently building a CH750. I have no intention of being drawn in to a flame war regarding CH650 vs Sonex, other than to state that I am *extremely* happy with my Sonex in *every*  way. It does *exactly* what the company states it will do (unlike other companies I can think of).

Who wrote that 'response'? It is chock full of misunderstandings, misinterpretations, ignorance of the facts, and just plain errors. The choice, to me, and one I researched in depth before setteling on the Sonex, was simply a no-brainer.

I have now said all I intend to say on this subject.

Comment by Jim Pensinger on November 9, 2011 at 7:06am

I have built two Zenith 601XL and one Waiex so feel qualified to comment on them.  My first XL was built from a kit and finished in 2005.  I had 770 hours on it when I had a bad takeoff accident in 2009 and totaled the plane.  I am alive now partially because of the engineering of the airplane.  I then bought a partially complete Waiex from another builder and completed it in 2010.  I flew it for 100 hours that year then traded it for another XL in 2010.  My current XL was completed, with the upgrade, in May 2011 and I now flown it 155 hours.

Both 601XL and Waiex airplanes are good airplanes and both have their good and, for me, bad points.  The 601XL is much larger, more stable with longer wings and wing dihedral, greater range (I put the optional fuel tank upgrade and have over 8 hours of fuel).  The Waiex was more “fun” to fly.  The Waiex controls are more balanced, with the pitch being similar to the XL but the roll much crisper than the XL.  My Waiex had the Aerovee engine and it was very underpowered.  Another Sonex at my airport with the Aerovee also was very underpowered so it wasn’t just my plane.  I flew in a Sonex with a Jabiru 3300 and it was a real performer although to stay under the max LSA speed limit, you had to run the engine below the suggested cruising RPM.  The Rans S19 has the same kind of “stretch the rule” philosophy.  I think the 650 canopy latching design is better then the XL.  The Sonex canopy is very flimsy and “designed to leak” at the front and especially at the gap on the rear.

All Zenith designs can be built from a kit or scratch built.  Only the standard Sonex (not the Waiex, Zenos or Onex) can be scratch built and then you have to buy the spar from the company because it is a custom extrusion.  All the parts of my Waiex were “beefy” and looked strong.  Parts in the Zenith planes are “eloquently” designed with, I believe, equivalent strength to the Sonex parts.

Zenith plans (11x17) and Assembly Manual are great.  Updates are available on the web, factory support is available anytime and you get real help and opinions.  Sonex drawings are large (D size), not well organized with different models and options on the same sheet.  There is no Assembly Manual, you are told to start with the smallest parts and just build!  I have a friend building a RV12 and they may have gone one step better than Zenith.  Their Assembly Manual is printed on their 11x17 drawings, putting instructions on the same piece of paper as the drawings.  That is a major improvement for Vans from their “D” size drawings and no assembly manual for other designs.  Sonex owners are a much more active group with fly-ins almost every month; probably because they got to know each other during the building process to make up for the lack of factory support.

Sonex gives e-mail support but their phone support is very limited and they wouldn’t help me with questions when I had problems with my Aerovee or give me any suggestions.  When I asked John Monet the performance difference between the two propellers recommended in their documentation, he said that in all his years of experience, he would only recommended one of them!  I tried a Aerocarb on my first XL (with a Jabiru 3300 engine) and it kept sticking.  I sent it to the factory and they said it was good and said that they had never seen that problem.  I offered to fly to their factory and show them the problem and they declined saying that they couldn’t look at a customer’s installation.  The day after I traded my Waiex, Sonex canceled my access to their website; Zenith never did that to me.  My 601XL kit and the Upgrade kit came complete.  Everything I needed was in it.  The Sonex kit, and their option kits, don’t come with hardware.  Wicks and Aircraft Spruce both offer hardware kits but they have different parts and neither are as complete as what was supplied by Zenith as part of the kit price.

I like to travel in my plane, take people and baggage with me and fly in light IFR conditions.  I don’t like to go up for an hour, by myself, on sunny days and do aerobatics.  After the plane is built, these are the differences. Mission, Mission, Mission.  The 601XL is for me, that is why I have a second one!

Comment by David Peterson on November 9, 2011 at 5:53am
I'm glad you posted this Sebastien and I think it's a worthy examination. I'm glad to see Zenith continue to stand behind the 650 and there is no doubt that the recent shakedowns and consequent mods make it one of the safest and most thoroughly scrutinized GA (not just LSA) aircraft around today. Case in point - I doubt many other aircraft of similar category have had comprehensive full scale (i.e. actual airframe) dynamic response / GVT testing, for example!

Zenith's reputation for support is also a major factor, as are avenues such as this site which provide a fantastic way for the Zenith community globally to connect. Keep up the great work and the customers will continue to figure out the rest! :)
Comment by Tracy Buttles on November 8, 2011 at 11:23pm

I have built both , the sonex with a VW is just too under powered   so the only engine option is the 3300 , then there is issues with  the cooling , nose gear,  range  and definetly room!    Of course the price goes up with the 3300 

 The sonex is realisticly a 1 1/2 person plane. Its true its a strong airplane, but overbuilt.

 the 601/650 is so much more room. Baggage area, range with the bigger wing tanks,forward visabilty,ease of construction.

and the guys at Zenith treat you like family!!!

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