SonexBuilders.net

Hey everyone,
I wasn't sure if I should post this here or in the introduction section, but hopefully this was correct. I know that I want to build a kitplane. It's a long story, but basically my dad and I were shopping for a kitplane to build together when he died and I'd put off doing it for a while, but finally really want to. We'd actually planned on building a glassair, then when I started looking for kits a friend steered me towards the Van's kits. To be honest the plane that I really want to build is an RV-8A. I mean no offense to you sonex guys, but that just really is the plane I want... want and can afford being two wildly different things, however. Lol, I mean I can't afford a Waiex, but it's located way closer to the realm of possibility.

The Waiex really caught my eye though. While I'm not crazy about the aerovee engine, it seems like you could build a decently equipped Waiex for at least half the price, if not slightly better, of an RV-8. My dad had a D-35 and then an S-35 Bonanza. The S was the first plane I ever flew, and the Y-tail Waiex just seems like it might be a neat little homage to the V-tailed Bonanzas I always loved.

Ideally I'd want the performance of the 120hp Jabiru engine, but the pricetag just doesn't make it worthwhile to me especially when I know I'd essentially like it to be Night IFR equipped. I'm not saying I'd ever fly it to minimums or that it'd be a fun IFR plane, however, I do fly in the SFRA and FRZ, so certain equipment is a must, plus I like flying at night. So I'd rather spend 1/3 of the Jabiru on the Aerovee.
What bothers me about both jabiru engines offered and the aerovee is that unlike even the rotax they are not dry sumped. Now, I don't really have any intentions of doing hardcore aerobatics, but oil starvation is a real thing on a non-dry sumped motor and having flown aerobatic aircraft, I know I want to be able to be upside down and do some loops and rolls. I don't really see myself doing that much more than the occasional loop, roll, split-s, high-G turn, etc, but I'd like to know the motor isn't being harmed in those situations. And take it from me, you can blow up a wet sump car, just driving on a banked racetrack. I'm curious how you guys who fly aero in your sonexes/waiexes protect your engines. Are there flop tubes for the gas pickups, etc?

I guess my main questions for you guys are impression of the aircraft. I like the fuel consumption, ability to run on 93 octane, and fully aerobatic load limits of the Sonex/Waiex. That makes it a really appealing package. The removable wings and trailerability are also a huge plus. Obviously it's not super fast, but with ground adjustable prop it might not be that bad on an XC flight. One of my big concerns is the gross weight, that it's just so light it will fly worse than a 152 on a windy day. Is that the case? How does it handle, how is it as far as aerobatics are concerned, There are a decent number, but not really that many kits flying, I'm curious on the big problems they tend to have, accidents, etc.

I'm not that worried about actually building the kit. I've worked in Porsche race shops since I was in college, I've built several race cars, kit cars, etc... lol, and I've seen some wiring A&Ps have done on Pipers... In fact, I was trying to find a partner to go in on a Van's with who had the money, but needed someone with the time, expertise, and tools to build one. Still, I'd love to hear some impression on how the Sonex builds actually go.

Anyway, I'm sorry for basically asking everything imaginable about the aircraft, and apologize if this has been asked over and over, but I really would like to know it all. It's one of my more important goals in life at the moment, to build a kitplane, and I really want to make sure I choose one I'll be happy with and will be safe and reliable and perform fairly well. I'd appreciate any advice, thoughts, tips, etc that you guys might have.

Thanks,

Wow. Lots of questions. I'll see if I can answer a few and maybe others can answer what I don't. As far as the RV vs Sonex I am in the same boat as you are. When I started building I really wanted an RV but didn't have the money. The sonex seemed like a nice compormise. I could build and fly a sonex for about what the engine costs for an RV. The down side is that it isn't as fast, can't carry as mugh luggage, and is a little tight with two people aboard. For me it was worth the tradeoff for cost and fuel economy. Don't forget that in addition to the extra cost to build an RV they also cost more to insure and to fly.

As far as night and IFR, the Sonex is not the plane for you if you want to do any insturment flying. It has neutral stability which makes it alot of fun to fly and gives it a sporty feel but since it doesn't have positive stability it is a handfull to fly on instruments. On a typical airplane when you let go of the stick the plane resumes back to normal level flight for however it is trimmed. In the sonex when you let go of the stick it keeps flying in the same direction it is pointed. If it is in a climb it stays in a climb, if it is in a bank it stays in a bank.

Aerobatics aren't a problem with the Sonex as long as you don't want to do sustained inverted flight. The aerovee and jabiru don't have inverted oil systems and more importantly the gas is gravity fed to the engine. When you pull a negative G the gas supply eventually stops flowing to the carb. There haven't been any reports of oil starvation from the folks who do fly aerobatics in their sonex. Loops rolls and spins are no problem. Go check out youtube as there are plenty of videos of people doing aerobatics in the Sonex.

As far as ease of building I don't think there is a better kit out there. The RV aircraft use to have the leg up on Sonex but now that Sonex has matched hole kits plus the use of pulled rivets instead of bucked ones the Sonex wins hands down. You will probably find that assembling the kit is the easy part of the build. The hard part comes when doing things like mounting the engine, installing and hooking up all the avionics, painting, etc. Those are common to all kitplanes and I wouldn't say that the Sonex is any easier or harder than the rest in those areas.

As far as safety is concerned the Sonex family has had about an average safety record. Most accidents were due to pilot error. There was one accident of a Waiex that had a structural seperation of the tail. The exact cause of that breakup isn't clear but there was quite a bit of evidence that the builder took some shortcuts and had some non standard building practices. Sonex to their credit did issue a service bulltin and provided a re-enforcing kit that could be retrofitted to the tail. If you do a search of the NTSB database you will be able to find the accident report which includes pictures and details of what failed and why. I will say that most RV builders that look at my sonex remark that it is built like a tank. Go compare the size and thickness of the wing spars in a Sonex to those in a RV and you will see what I mean.

Hope this helps some.

Keith

Welcome to the forums! I'm sure you'll get plenty of good info from the group here. Lots of knowledge in this bunch. I offer the following comments to your questions, and as a "truth in advertising" preamble I want you to know that I am a Sonex employee. But I was a Sonex builder before I was an employee, so please take that into consideration. With that in mind....

Wastintime wrote:While I'm not crazy about the aerovee engine, it seems like you could build a decently equipped Waiex for at least half the price, if not slightly better, of an RV-8.

You are correct in that building a Sonex (any version) will take a much smaller bite out of your budget than any RV project. The Sonex mission is to offer you the most performance for the dollar of any kit on the market.

Why are you "not crazy" about the AeroVee engine? I have built two aircraft powered by the AeroVee (a Sonerai II and our Sonex) and I have found it to be a very reliable and economical engine. Easy to work on. Inexpensive to maintain and repair. What's not to like?

Wastintime wrote:Ideally I'd want the performance of the 120hp Jabiru engine, but the pricetag just doesn't make it worthwhile to me especially when I know I'd essentially like it to be Night IFR equipped. I'm not saying I'd ever fly it to minimums or that it'd be a fun IFR plane, however, I do fly in the SFRA and FRZ, so certain equipment is a must, plus I like flying at night. So I'd rather spend 1/3 of the Jabiru on the Aerovee.

I will echo the sentiments of the previous reply. The Sonex/Waiex is NOT an IFR platform. There's nothing wrong with night VFR, and in fact having lights and strobes on the airplane is a good idea. But don't for a minute consider sticking your nose in the clouds in a Sonex/Waiex. It's not the right plane for you if that is one of your mission requirements. Certainly you have have the required transponder and encoder installed at minimal weight and panel space penalty, so no worries there.

Wastintime wrote:Now, I don't really have any intentions of doing hardcore aerobatics, but oil starvation is a real thing on a non-dry sumped motor and having flown aerobatic aircraft, I know I want to be able to be upside down and do some loops and rolls.

The engine (either AeroVee or Jabiru) are fine for positive G aerobatics. If you "go negative" the engine will quit from fuel starvation long before there is even a hint of damage from oil starvation. Many pilots have done full aerobatic routines in their Sonex/Waiex with no ill effects. This is not a problem at all and is not something to be concerned about.

Wastintime wrote:Obviously it's not super fast, but with ground adjustable prop it might not be that bad on an XC flight.

Considering the power, I think the Sonex/Waiex does a pretty good job in the speed department. A heck of a lot faster than many standard category "cross-country" airplanes. They aren't Bonanzas, but you're not burning 16 gallons an hour either. One Waiex builder who frequents these forums has been to all 48 contiguous states, so you can't say the airplane isn't good for cross-country flying!

Wastintime wrote:One of my big concerns is the gross weight, that it's just so light it will fly worse than a 152 on a windy day. Is that the case?

The Sonex line does a good job handling the bumps. I find the Sonex (and the Waiex is identical) to be a much nicer ride on a bumpy day than my old Piper Pacer used to be. You won't notice the bumps any more or less than any other light GA airplane.

Wastintime wrote: How does it handle, how is it as far as aerobatics are concerned,

It is a "fingertip" airplane. VERY light on the controls and a joy to fly in any maneuver. I have never had a pilot come away from flying a Sonex who did not thoroughly enjoy it.

Wastintime wrote:I've worked in Porsche race shops since I was in college, I've built several race cars, kit cars, etc...

Cool! I used to race Porsches, back when I was young and fearless! Great cars!!

Wastintime wrote:Still, I'd love to hear some impression on how the Sonex builds actually go.

We built our Sonex as a group project, with the aim of introducing aircraft building to a bunch of people who had never done any. We ended up with a VERY nice flying airplane. Everyone easily grasped the tasks at hand and the plans and instructions. I think the Sonex plans and kits are among the best in the industry. (And I say that from the viewpoint of the fact that I used to be an FAA DAR, so I had a chance to look at many different designs, kits, and plans.)

Hope you find the info in this post, and on these forums, to be of use. And I hope you decide to build a Waiex. I'm sure you'll enjoy both the build process and the flying!

Cheers!

There was one accident of a Waiex that had a structural seperation of the tail. The exact cause of that breakup isn't clear

Actually the NTSB found that the Waiex was designed with improper engineering for y/v tail aircraft. Sonex immediately issued a fix before there was any preliminary cause.

From the NTSB report (mentions nothing in the report of poor build quality)

"It is likely that the pilot, distracted by the loss of engine power, allowed the airplane to enter an unusual attitude, and the tail separated during the pilot’s attempted recovery from the unusual attitude."

"The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The in-flight failure of the aircraft’s Y-tail attachment structure during maneuvering flight due to overload. Contributing to the accident was, the kit manufacturer’s use of 14 CFR Part 23, Appendix A design guidelines intended for a conventional tail airplane without a V- (or Y-) tail."

One other thing I have heard multiple Waiex pilots complain about is that while in the air they handle similar to the Sonex, on the ground they are rather limited in crosswinds because lack of rudder authority. I have heard Waiex pilots say anything over 7mph starts getting a little wild. I know some have told me they have to line up on one edge of the runway because they will be pushed over to the other side before yaw becomes effective. Some have gone in the grass off the side of the runway because of this.

As for acro, I am still not convinced the Y-tail is up to par with a conventional tail. I have time in both and while they do behave similarly they are not the same. I have done some minor acro in a Waiex but don't see it as a competitor in sportsman class acro where the Sonex can be. One other thing on the acro, with the aerocarb/aeroinjector, it does not regulate flow. So in a routine your mixture will be all over the place, way lean over the top of a loop, to way rich coming out of the bottom. A buddy of mine who flys advanced/unlimited comp put a Sonex through the sportsman routine and said the airframe is fine, but the carb was nowhere near what he considered acceptable since he had the motor stall out twice during low g maneuvers due to fuel starvation form the lack of flow regulation.

Just a couple of thoughts for you to consider.

Wastintime wrote: Still, I'd love to hear some impression on how the Sonex builds actually go.

Welcome, Andy!

Long post so I'll just hit on a small part of it. I had zero build or metalworking experience before purchasing my Waiex kit last fall. So far, building the kit has not been overwhelming. There is a lot to learn, but the support from Sonex has been great and most everything goes together in a very logical manner (i.e. if you have to get creative to get something to fit/work, it's probably upside down! etc.) There are lots of builder blogs out there, and I invite you to visit mine (link in my signature). I tried to make it somewhat in layman's terms while still having some technical bits, so it might help you get a feel for what the project is like.

Well known fact to us builders... up to 50% of the time you spend will be deburring holes and edges, it's an essential fact of building and if you can handle the recurring monotony of it, you can handle the whole airframe project.

I have not purchased an engine yet, but currently the Turbo Aerovee project is currently at the top of my wish list.

BK9977 wrote:One other thing I have heard multiple Waiex pilots complain about is that while in the air they handle similar to the Sonex, on the ground they are rather limited in crosswinds because lack of rudder authority. I have heard Waiex pilots say anything over 7mph starts getting a little wild. I know some have told me they have to line up on one edge of the runway because they will be pushed over to the other side before yaw becomes effective. Some have gone in the grass off the side of the runway because of this.

I will quickly, and gladly, refute this claim! It is my full belief that any pilot having trouble landing a Waiex in a crosswind is having trouble due to pilot technique or ability, not Waiex capability. On several occasions during transition training last summer I had the opportunity to ride with customers while we worked on crosswind landings in the Waiex. On one of these occasions we had a 17 knot crosswind directly 90 degrees to the runway (from the right, in case you're wondering). On every occasion, including this extreme case, the customer handled the landing with no help from me. Too, I have had a couple of occasions while flying the Waiex myself when I had fairly significant crosswinds during takeoff and landing. I find the airplane to be more than capable in a crosswind. No less so than a Sonex, or any other airplane I have flown.

BK9977 wrote:One other thing on the acro, with the aerocarb/aeroinjector, it does not regulate flow. So in a routine your mixture will be all over the place, way lean over the top of a loop, to way rich coming out of the bottom....

This is very true. The AeroInjector, much like any throttle body injector without a pressure regulator (such as the Posa, etc.) will react to head pressure changes by varying the mixture. It is something that one simply needs to be aware of and plan for. It is a VERY simple system, which makes it very resistant to problems. But this being the case it is not the perfect system for every application. Be aware of its characteristics and limitations and life is good.

Cheers!

Wastintime wrote:Do I want to build a Waiex?
...

Sounds to me like you want to, no question about that :-)

If you really want an RV8A, you can have one. Just allow more time so you can spread out the $. In '89 I started an RV4 tail. Life made me decide I couldn't afford it and I built most of a hummelbird. Got distracted by a C140 project. Now I am building the Waiex. If I had stuck with the RV4 it would probably been done by now. The 24 years would have taken the bite out of the finances. They are great airplanes. If you are unwilling to trade time for affordability then the Waiex is a good choice. I don't think you can expect it to be a combination Pitts/Bonanza substitute though.

Thanks Joe for your commentary on Waiex crosswind capability. That is very relevant to me. The high wing piper taildraggers were pretty good. The Pawnee was ok but the low wing creates limits. The arrow was weak but it is a Cherokee so pretty safe.

Wastintime wrote:... Ideally I'd want the performance of the 120hp Jabiru engine, but the pricetag just doesn't make it worthwhile to me ...

You have more choices than just the AeroVee, J3300 or J2200.
Some of the other VW conversion like the RevMaster 2300 or the Hummel 2400 will deliver slightly more power than the AeroVee at the same cost or even slightly lower. These engines will pretty much bolt straight onto the standard VW engine mount which is used for the AeroVee (slight modification needed for the RevMaster but fairly easy).
Also have a look at the Corvair, Dale is a very active member of this forum and he has built a very nice Corvair Sonex which I believe has similar power to the J3300 but at almost half the price. There is a slight weight penalty using this engine though and the mount/cowl is not standard. You'd need to talk to Dale to see how these are manufactured or where they can be sourced from.
Finally you could also consider a 110hp Viking engine it also uses the standard VW mount with an adapter but I would personally strongly recommend against this engine, you need to read the Viking related topic on this forum (under other engines) to understand why, but in the end you'll need to make your own opinion.

Sonex has also been announcing (for 3 years now :| ) a turbo version of their AeroVee and word is that it might finally be released this year.

If you decide to go with a VW based engine (or a Viking) you can pretty much order the kit now and decide on which one you go with at the time you need it (which would be years from now unless you're the fastest builder ever), like I mentioned the mount is the same and while you're building your Waiex who knows what might happen, the R-3000 might eventually become available, the Aerovee Turbo might get released, Jan at Viking might finally get his act together, ...

BK9977 wrote:Actually the NTSB found that the Waiex was designed with improper engineering for y/v tail aircraft. Sonex immediately issued a fix before there was any preliminary cause.

Sonex was quick to say the two events were not related. I do appreciate the fact that even though the Sonex is an experimental aircraft it was designed and tested to Part 23 Standards. But it seems that they were guilty of using an earlier version of the standards for the Y-tail and thus when the new standards were used the new parts and recommended updates to the air frame were taken care of immediately.

One other thing I have heard multiple Waiex pilots complain about is that while in the air they handle similar to the Sonex, on the ground they are rather limited in crosswinds because lack of rudder authority.

You are not the only one hearing this. Go to a Sonex fly-in and talk to the pilots that have flown both. There are a half dozen or so on this forum that have stated as much though I suspect they aren't willing to get into a spitting contest over it. A good thread for this disscussion is found on the Waiex Plans Yahoo group. Of course the factory's line is "they fly EXACTLY the same" which is an impossibility because the design is not the same.

As for acro, I am still not convinced the Y-tail is up to par with a conventional tail. I have time in both and while they do behave similarly they are not the same.

I have the conventional tail. I prefer the looks of it to the Y-tail but I'm different that way.

I'll also echo those that insist the Sonex is not for IFR. It isn't ... forget that.

As for the Aerovee; it does what Sonex says it will do. A bit short on the get up and go unless you fly small folks in cool air. I would never fly one in the dark but at the moment I can't think of very many engines that I would trust in the dark. But again, I just different that way.

My $00.02 that is not supported by any government stimulus program and worth EXACTLY what you paid for it.

Dale Williams
N319WF @ 6J2
Myunn - "daughter of Cleanex"
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
53.2 hours / Status - Flying
http://kitplanes2.com/blog/2013/12/ownerbuilder-2/