SonexBuilders.net

An O-200 with a Skytec starter, lightweight B&C alternator, no vacuum pump, and maybe replace the mags with an electronic ignition, probably would come in under 200 lbs. But it would probably cost the same as a used Jabiru 3300.

And which one is more dependable????? If you like to overhaul every 200 hours the Jab and the aerovee are for you. If you want 100 hp pick up a used Rotax 912ULS. They may look complicated but in reality are very easy to install and work on. If Sonex supported the Rotax I would build another tonight. I wonder why the Black Friday was offered????????

I have done a thorough search of the NTSB accident reports and I can find no Aerovee engines (or other major VW conversions) where the engine had a catastrophic engine failure. The VW engine failures were either lost power for indeterminate reasons, carb ice, gross maintenance errors, or overwhelming improperly installed engine controls or accessories. In other words, a throttle cable coming loose can be just as hazardous as throwing a rod.

In regards to the previous posters snipe about 200 hour overhauls, I wave the BS flag on that one. Maybe if you run too rich or overheat your engine you will need a top overhaul early but there is no reason an Aerovee or Jabiru can't go to the recommended TBO.

I will also second what Noel said, if you start engineering your own firewall forward, you better be patient, have lots of money, and be a pretty decent test pilot.

As far as adjustments on the Aerovee there are really only three things you can adjust: 1- Valves, 2 - Timing, and 3 - Mixture needle

Finally, you can overhaul an Aerovee that is on an aircraft and get it remounted on the aircraft in less than 40 hours and for less than $1500. The guy in the hangar next door to mine just wrote a check for $47,000 for some engine work on his Cessna's lycomming.

On another note, building and maintaining an engine is not for everyone. If you don't want to build the engine go with the Jabiru or Camit.

On a closing note if Sonex offered an FAA certified engine option and I had lots of extra money I would probably go that route. However, in reality I can not afford to operate and maintain any engine except for the Aerovee so I have worked diligently to know it inside out and to configure it as safely as possible.

Jake

I believe the Aero Vee can be a reliable engine, as many Sonex fliers have good luck with them.

I do wish Sonex would look beyond the Aero Vee and Jabiru and support other engine installations such as the Rotax 912.

While many are happy with the Aero Vee, I had nothing but bad luck with mine. It leaked oil from several places, constantly overheated, I had problems with both ignition systems, and the Aero Carb never worked to my satisfaction. On the rare occasion that it ran properly, I felt the aircraft to be underpowered. The final straw for me was when an exhaust rocker broke and I had to make a dead stick landing. It was my wife's first flight in the plane. I trucked it home, put it in the hangar and removed the Aero Vee. These are just my experiences, not a slam on VW conversions in general, but I'll never fly behind a VW again.

i looked at other engines, giving consideration to Jabiru, Corvairs, D-Motor, UL, and Rotax before settling on the Viking. I am a big fan of all things Honda. The install has been fairly straightforward and Viking has been great to deal with. I am finishing up some wiring work and should be running the engine in December or January. Two other Viking Sonex are flying with over 800 flight hours between them, so I don't really expect any problems. The Viking is heavier than the Aero Vee, but part of that was offset with light weight batteries. It isn't for everyone, but I like having a modern, liquid cooled, fuel injected, computer controlled engine.

Modifying an airplane isn't for everyone. I spent (or mis-spent) my youth working in aircraft modification centers as an A&P mechanic and as a project planner. As far as mods go this one has been fairly easy to carry out, but I can understand if most folks stick with the tried and true path. You need a certain skill set and level of confidence when you do something not covered in the plans.

I don't think I will have to be a major league test pilot to fly my Viking Waiex. My Aero Vee Waiex was so unreliable I always felt on edge. I always felt like a test pilot with the Aero Vee. I've had my engine out experience and that was with the "approved" engine.

To each his own, be happy with your engine choice and fly safe. I do believe the O-200 with accessories is too heavy and too large for the Sonex. A better choice might be the CAMit 3300 engine. Money was never a deciding factor in my re-engining choice. Sometimes a cheap engine is just a cheap engine.

Not trying to start any arguments, just offering an opinion and another data point.

Don Bowen
N49YX
Viking Waiex

Plane looks great Don.
Been following your conversion. Eager to see how the Viking flies the Waiex.

One thing, a major thing, that nobody has brought up in this conversation is the propeller. Even if the engine was the right weight (it's not) and the right physical size (it's not, especially for a Onex), and if you didn't have to engineer an engine mount for it (which you do), you still need to consider ground clearance for the propeller. An O-200, or a C-90 (or even an A-65) produce their power and torque in the range of about 2300 to 2700 rpm. In order to make that power at that rpm useable, the engine needs to swing a 72 to 74 inch propeller. That's 20 inches (!) longer than the 54 inch props typically used on the AeroVee or Jabiru. That means the prop is 10 inches longer on each blade. That would put the prop tip about 2 inches from the ground on a Onex or 4 inches from the ground on a Sonex TAILWHEEL airplane, and closer on a tri-gear. And that's on an empty airplane, sitting still in the hangar. Put some weight in the plane and start taxiing and see how long you make it before you catch a prop tip on the ground. And don't forget to take off and land ONLY in 3-point attitude, lest you hit the runway with the prop.

Sure, you can run a shorter prop, but now you have to turn up the rpm in order to get the performance. Yes, the O-200 can turn more than 2700 rpm, but running constantly at higher rpm will shorten the life of the engine accordingly. And when you do need to top or overhaul the engine, think about the cost. One cylinder assembly for an O-200 costs about as much as EVERYTHING you need to overhaul an AeroVee. Two cylinder assemblies for an O-200 cost more than as EVERYTHING you'd need to overhaul a Jabiru 3300. And you'll be totally on your own in figuring out just what prop will work, which will probably entail buying and trying several propellers before finding the right one. Don't forget to add that to the cost of engineering your installation.

There are a number of engines that can be engineered to fit the Sonex or Onex. But for many reasons that have been outlined in this thread by myself and others, I truly do not believe that the O-200 is among them.

As always, your mileage may vary.

Good point regarding the propellor.

The Viking runs a three blade ground adjustable Warp Drive prop for these reasons.

I'm not encouraging anyone to modify their planes. The Viking is a little heavier than the Aero Vee and is not supported by Sonex. This is, however, "experimental" aviation and I'm charting my own path.

I will continue to post progress to my kit log page, including flight test and operational data. I am hopeful that the Viking Waiex will be a good plane for my purposes, but we will see what we will see. I don't drink anyone's cool-aid, not Sonex's or Viking's.

Don

The weight of an O-200 can be kept below 200lbs as previously mentioned. A light wt aluminum oil tank is also available and short exhaust stacks ala Formula 1 help reduce wt too. A prior poster mentioned the complications associated with designing an entirely new firewall forward for an unsupported engine. This isn't the case with an O-200, there's nothing complicated or exoctic here. These engines are so plentiful that many of the light aircraft design books have detailed engine mount drawings and other very detailed installation information. The new cowling needed for the O-200 would likely be the builders biggest challange.
Regarding cost, I think using an 0-200 would be at least comprable to a vw installliation and much cheaper than a Jab or Rotax. Entire O-200's can be had for $5000. $10000 would build a good O-200 if you're a careful shopper. Of course I'm not taking about a repair station overhaul, but lots of Sonex builders build their vw's so why not build an O-200....it couldn't be simpler. When I was racing F1 years ago I completely tore apart my O-200 on the hangar floor with our one year old baby and my wife looking on. The following morning I qualified the airplane. If you want more power, an 0-200 can put out gobs more than 100hp with forged pistons, porting and do it very reliably.
Ive noticed the the Zenith folks have wisely chosen to design around the O-200 now and selling lots of airplanes because of it.
Having said all the above I wouldn't build a Sonex and hang an 0-200 on the front for the simple reason that the kit producers don't indorse it. If they ever do I'll be the first to buy the kit because I like the airplane.

I'm sold on the Willliam Wynn Corvair and would build with nothing else. It can be built cheaper, or go full tilt with a new forged crank and 92mm barrels and come in lighter than the O-200.
It was designed to make up to 180 hp at 5500 rpm, and is loafing in the aircraft version. William is eccentric, however he tests his products intensely. No need to engineer a motor mount because his business partner Dan sells them ready to go. The new 5th bearing setup is well engineered and well made.
Standard Marvel Shebler carb, redundant ignition, no junk Chinese parts. I've actually TRIED to blow a turbo model in a car up without success.
Zenith has embraced their engine and supplies EVERYTHING necessary for a full install down to cowling, exhaust, etc.
Dan built the first 'Cleanex' and now offers nose bowls, exhaust, mounts, and almost everything necessary to do the install on the Sonex. But still Sonex stonewalls their product.
Remember that there are almost NO old parts in the Corvair airplane engine. Cases, oil pump accessory case, and if you choose to build frugally, the forged crank that GM spent 100's of millions to develop.
A 100 hp model just sold on Barnstormers WITH a new Dan Wessman crank and rods, exhaust, carb, intake, baffling for under $6,000. Models can be built up to 125 hp with Dan's new 'stroker' crank.
And remember: an engine that was DESIGNED to run at up to 5,500 rpm.
I just don't get Sonex' resistance unless it's purely personal with William. I'm not buying someone with a 'normal' personality. I'm buying a bullet-proof engine that I trust my and my loved ones life.
I have NO CONNECTION to either William or Dan. But I've been a fairly decent aircraft mechanic and restorer for the past 40 years and have a lot of experience with a lot of different power plants. The LAST one I'd consider a potential candidate for aircraft use would be the VW.
JMHO

Nothing is bullet proof- there are far too many issues with the VW derivates, the R912 and the Jabs, to merit anything near such a statement.

Neither is the Corvair. There are plenty of cases of Corvairs converted to aircraft use with all the tricks in the books- forged crank, fifth bearing- you name it- that have quit.

The argument that the engine was designed to operate at 5500rpm is invalid: only for very short power bursts, and with a HUGE vibration damper (transmission and tyres) in the driveline.

Thanks
Kai