RV-12 vs Sonex

Hey all...

I'm a first time builder, currently about 600hrs and halfway through a Sonex (tail done, fuselage 90%). Frankly, I'm finding the build a bit frustrating. The kit requires a lot of fabrication, with all the builder error that can generate. I've scrapped or re-built a LOT of parts during the process. I've learned a lot, but frankly I was hoping for a less stressful building experience.

I'm considering abandoning the Sonex in favor of starting an RV-12. I have heard some conflicting information though...some sources have said:

1) The kit comes with all parts completely pre-cut & formed (no more fabrication?!?)

2) All holes come match drilled out to final size and deburred (no more deburring?!?)

However, I read some builders talking about deburring edges and skins, and this has me confused...is the kit deburred from the factory or not? Or is it just the holes deburred, and you still have to smooth tool marks/nicks in angle pieces and skins?

Honestly, if 1 & 2 are correct, it sounds almost too good to be true. In fact, if that's right what is involved in building an RV-12 airframe other than just aligning parts, clecoing, and riveting? I'm sure there's more to it than that, but it sounds a **** of a lot easier than the measuring/drilling/cutting/bending operations I've been doing, and a lot less prone to builder error.

I'd love to hear what your experiences are with the RV-12 kit, especially where you think there are any real problems or difficulties in building the RV, or if you have any Sonex building experience to compare with. Do you feel the plans/instructions are clear?

Thanks!

I feel your pain. I visited the Sonex factory and looked over Sonex very well before settling on the RV12, and my next project wll probably be a OneX. There is a LOT of difference in the two planes. One of the factors was the very narrow cockpit of the Sonex along with a lot more building time required. I am 74 and want to do some flying, not spend the rest of my life building.
Some of what you have heard is incorrect, there IS matchdrilling required, deburring of sheets and holes ARE required, and there is some minor fabrication of pieces from stock, very simple and easy though. Since I have not actually built a Sonex, I can assure you the RV12 is far easier, far less complicated, and far faster as a result. I have actually enjoyed the building process, it was all been fun and fast. You can click on my builders log to get a feel for the speed of building, yet I am in no race to get it done, it is so much fun to build!

First time builder. Only one part ruined - a $5 stall switch mounting plate that I countersunk on the wrong side! (Even after I marked it!!!) Fabrication? As close to zero as you can imagine, like cutting some funky-shaped pieces from angle aluminum. (A small amount of fab had to be in the kit to meet the nebulous 51% rules that were in transition at the time the -12 was designed.) Some people had issues doing the longerons - described as the toughest task in the kit. Search this forum for THWACK to see how easy it an be. The kit is phenomenal.

You do have to deburr the edges of the pieces. A scotchbright wheel on a grinder takes care of this, and a deburr tool for the inside of some lightening holes if you want to deburr them. A deburr bit in an electric screwdriver will get a lot of use. A small-diameter scotchbright weel, an electric drill, and one leather glove makes easy work of deburring edges of large pieces of aluminum like the wing skins. No jigs. 99.5% of holes are drilled to final size. Your own levels of workmanship will determine how much deburring you do, I did a lot and it was not a problem at all.

There are wonderful blogs that show you exactly what you will have to do. My favorites are:
http://www.schmetterlingaviation.com/
I made the decision to build the plane after reading that one. He has a 56MB pdf file you can download covering the 1st half of the build in entertaining detail.

An early builder is here. About every small issue he found in the kit has been taken care of in subsequent revisions:
http://martysrv12.blogspot.com/

Absolute perfection in workmanship can be seen in this set of photos:
http://tonytessitore.smugmug.com/RV-12Project

And for a quick look - just pics - of the entire build you can see my public facebook album. What you see took<950 hours total of a very careful 1st time builder.
http://www.facebook.com/media/set/?set=a.151245628228677.26907.100000297210697&type=3&l=a2b29e894a

Building "Sweetie" was a huge amount of fun and almost zero frustration.

I recommend those mentioned blogs plus a few hours spent searching through this absolutely invaluable forum. Good luck!

Acording to the facyory the pre punched rivet holes do not need to be deburred.

But a lot of builders debur anyway. Very much like primer arguments.

The few holes the builder drills do need to be debured.

The edges of sheets/parts do need to be deburred.

The kit is really amazing. The parts do fit. In fact if they don't you've done something wrong.

The aircraft easily accomodates two 220+ people both in weight, center of gravity, and size.

Visit a builder,otherwise it is just not believable.

-Dave

To give you an idea, I'm a first time builder and my partner and I assembled the wings in 2 weekends. We then assembled and mounted the flaperons on the third weekend. Noticed I used the word assembled. Its like assembling a big erector set with good plans. By the way this forum is invaluable with people like Marty, Larry, Jetguy etc. that are always willing to help out.

The minor fabrication is actually fun.

The kit is so complete I actually ended up with some extra parts...

Gary E

Dont forget the fiberglassing of the canopy leading edge. Dont really know how difficult it is because I have yet to begin that task. Kinda dreading it too. That will happen this fall.

If you want to get a good feel for the construction of a RV-12, go to www.HomebuiltHELP.com. They have a number of well documented
DVD's that demonstrate the building of the RV-12. I used them for building my RV-12 and between the DVD's and this forum all my question were answered.

Welcome to VAF!!!!

MrMorden said:

Hey all...

I'm a first time builder,

Click to expand...

Andy, welcome to VAF

Good to have you aboard.

Thanks for all the great information. Wings in two weekends? I was about to order my Sonex wings and figuring on 200 hours or more.

I think the last straw with the Sonex was when I looked at the nosewheel strut and saw that the fork only has one side drilled for the axle. I figured it was a factory mistake...nope, I have to drill ONE side of the fork. I mean...really?!?

So some more questions:

1). One of the things that attracted me to the Sonex is the strength of the airframe, rated at +6/-3g...not because I want to do a lot of aerobatics, more just for the extra margins. How strong is the RV-12 airframe? What are the weakest parts. Also, what is the Vne?

2) the Sonex has no solid rivets, except in the wing spars I have not done yet. I know the RV uses quite a few of them...how hard is working the solid rivets vs the blind rivets? Are the blind rivets aluminum or stainless steel (all the Sonex rivets are SS).

3) The Sonex uses 6061-T6 aluminum, whereas the RV uses 2024 alclad (I think). I'm used to sanding out scratches and nicks that happen inevitably from handling in the shop...how do you deal with this with alclad?

4) does the canopy come ready to install, or does it need trimming?

Thanks again for all the quick and helpful information!

easy build

The Rv-12 is an extremely easy build
it's more of an assembly than a build really.

The factory pre drilled cut and shaped parts are of excellent quality and fit together beautifully.
Like someone here said already, if the parts are not lining up, then you have them the wrong way around, it's pretty foolproof.

There are a few, and I mean REALLY few, holes that need to be matched drilled, I assume for the 51% rule.
It's quite odd, you often get a piece with hundreds of holes pre drilled and you just cleco it together then there's 4 holes they have you "match drill" for no other reason I can think of than the 51% rule.
it's really trivial, and honestly a bit silly, obviously originating in some government rule.

There's a handful, really not many at all, maybe 8 or so bits that you fabricate from angle stock, again, totally trivial to meet the 51% rules.

It's a fantastic quality kit. Like I said, an assembly more than a build.
in fact I wish there was more fabrication, I actually enjoy it, but I feel your pain, I think in fact if I had to fabricate everything I would be overwhelmed too,

The longerons that people complain about are really not hard at all, I think it's just that the rest of the kit is so easy, that it just seems hard to make the longerons because that's just about the only place there's any real fabrication work to do !.

I have not done the canopy fairing yet, but I expect that only to be a problem because it's the only place on the kit that requires any fiberglass work, and so that will be new skills to learn.
And if that's daunting, then you can buy a prebuilt fairing anyway.

Vans will sell you a pre-built leak tested fuel tank if you want too.

I can't imagine an easier build than the -12.

Deburring? yes, edges must be deburred, especially the inside of the lightening holes of the wing ribs and any holes you drill (but there's really not that many).

Get a 1" scotchbrite on a drill or angle grinder and just do it.
it's not that bad, it does take a bit of time, but again, it just seems like this is the worst bit because the rest of the build is just cleco it together and bang the rivets in.
Even the riveting is trivial, nearly all rivets are the blind pop rivets, and you can use a pneumatic puller, it's childsplay.

There are some squeezed rivets, but nothing over -4 sized and no rivet needs to be set with a rivet gun, all you need is a 3" squeezer.

I do deburr all holes, but I've been told that you really don't need to deburr the holes from the factory if they are going to get a rivet.
it's really not hard or even that time consuming with an electric screwdriver and deburr bit (I like the one flute ones from Cleveland)

No jigs to build, no incidence angles to set, no plumb bobs, everything just fits together and gets secured with fasteners.
Just a few match drilled holes and a few holes final drilled (opened up to final size) and some countersinking and a handful of brackets fabricated from angle stock.

Two weekends is a record for sure !
it took me longer that that.
but yes it's easy.
I found that the wings were one of the slower parts of my -12 build.
I spent a few weekends deburring the ribs, I could probably have done it quicker, but I like to take my time and do things right.
There's a lot of fiddly bits on the edges that take different sized files to get into all the little corners, I probably went over the top with my deburring, but I figured wings were kind of important during flight...
The ribs also need to be fluted straight, it's all trivial, but there's a LOT of ribs.
once that's done though, the wings to assemble, and that part was done in a weekend, really satisfying !.

I don't know the specifics of the airframe strength, but the factory SLSA is a certified (to ESTM? LSA standards) airplane.

All rivets on the -12 are aluminum, well, there's a few blind SS countersunk rivets on a couple of nut plates, but they are no trouble.
All the solid rivets are -AD (aluminum) rivets.
They are no trouble at all, you squeeze them with a 3" yoke, either a hand squeezer or a pneumatic squeezer if you happen to have one handy.
No rivet gun or bucking is required for the -12 at all.

keep the blue protective coating on the alclad while you work with it.
that avoids scratching.
but there's little to no actual work to be done on the parts, so you don't need to worry too much about it.
There's some 6061 for some AEX and tubing, but i've never buffed out any scratches, I do prime the 6061 parts though, as directed in the plans.
There's really very little of it.

The canopy needs to be trimmed AFAIK.
I haven't done that bit yet, but I don't think that is one of the hard bits, you just trim it with a dremel and a cutoff wheel.
AFAIK the only hard bit of making the canopy is fabricating the fiberglass skirt (unless you decide to buy a pre-built one)

MrMorden said:

Thanks for all the great information. Wings in two weekends? I was about to order my Sonex wings and figuring on 200 hours or more.

I think the last straw with the Sonex was when I looked at the nosewheel strut and saw that the fork only has one side drilled for the axle. I figured it was a factory mistake...nope, I have to drill ONE side of the fork. I mean...really?!?

So some more questions:

1). One of the things that attracted me to the Sonex is the strength of the airframe, rated at +6/-3g...not because I want to do a lot of aerobatics, more just for the extra margins. How strong is the RV-12 airframe? What are the weakest parts. Also, what is the Vne?

2) the Sonex has no solid rivets, except in the wing spars I have not done yet. I know the RV uses quite a few of them...how hard is working the solid rivets vs the blind rivets? Are the blind rivets aluminum or stainless steel (all the Sonex rivets are SS).

3) The Sonex uses 6061-T6 aluminum, whereas the RV uses 2024 alclad (I think). I'm used to sanding out scratches and nicks that happen inevitably from handling in the shop...how do you deal with this with alclad?

4) does the canopy come ready to install, or does it need trimming?

Thanks again for all the quick and helpful information!

Click to expand...

Maybe I shouldn't comment on how hard the RV-12 is to build, since I haven't built one. I just stood back and watched a bunch of high school kids do it. Okay, I did mentor and instruct some! I think we have bought one or two replacement parts.

There is deburring of the edges of the parts, and we did deburr most holes on one side. VERY little fabrication, and no jigging at all. Some match drilling, maybe 3% of the holes. Solid rivets are pretty easy, in fact I like them better than pulled, if they don't require countersinking. That is just me, YMMV.

I am watching the second high school group build now. They will make mistakes, I'm sure, but will learn to correct them, just like the first build group. It is easy to understand, and it is a great design. I don't think you can go wrong, and you have all the skills you need to really jump into an RV-12. Don't look back...

Bob

P.S. On the quality of the instructions: 90% of the questions the students asked me were answered, "Read the instructions." They aren't perfect, but they are very good. They are the best I have seen with any airplane.

Instructions included

Hey folks, I'm really happy to see this thread...I'm in the planning/dreaming stages right now and find myself going back and forth between the Sonex and RV12 (truth be told, I always find myself back on the RV for one reason or another). It's great to see all the comments backing up my thinking

Anyway, the big question for me is the instruction/builders manual. As I read through VAF I often see a page from the plans, but there aren't really any instructions on those. So what are the instructions like? I *really* wish Vans would sell a preview instruction/plans set for the -12.

For examples of the plans go to the bottom of this link:

http://www.vansaircraft.com/public/notices2.htm

I was able to purchase plan sections from Vans without a problem, but the above link will provide plenty of free pages and entire sections to download and study.

Also the RV-12's limits are +4, -2

Vne, 136 kts cas, can be found in the POH that also can be downloaded from the above link.

fmiddleton said:

Hey folks, I'm really happy to see this thread...I'm in the planning/dreaming stages right now and find myself going back and forth between the Sonex and RV12 (truth be told, I always find myself back on the RV for one reason or another). It's great to see all the comments backing up my thinking

Anyway, the big question for me is the instruction/builders manual. As I read through VAF I often see a page from the plans, but there aren't really any instructions on those. So what are the instructions like? I *really* wish Vans would sell a preview instruction/plans set for the -12.

Click to expand...

Let me tell you about the Sonex build manual: there is none. The plans are good, excellent, even fantastic (they were made by a Skunk Works engineer who worked on the F-117 plans). But there is no manual per se. The plans contain build orders on some pages, but in general you look at the plans and just build based on the pictures and descriptions.

This is a fine, efficient way to show an airplane build. But there have been many times I have scratched my head and said "should I drill this first, or after I attach this other part?". Granted, 90% of those questions are simply answered by studying the plans until you get the eureka moment. But sometimes you can't quite get it, make your best assumption, and get it wrong. Sometimes it's easy to correct, sometimes it's a trip to the Sonex web store for a new part.

As a novice builder I'd prefer a step by step manual.

Download those example plans from the links above. Every page and step in the plans is numbered and the plane can be built from following those exactly. There are a *very* few things that people have chosen to do out of order based on experience that are covered in the forum - like not putting in the rear window until almost the last thing and ditto for the 2 skins that frame it. Putting in the brakes with the fuselage tub still on its side. Really minor stuff like that - stuff you will find by reading the experienced builder's blogs before you start that section, and a couple of easy searches on this forum. For example there are about 3 or 4 documents here giving summary "what to watch for" detailed advice on each section of the plans. I was on a business trip after I went to OSH in 2010. Each night I read from the blogs I mentioned above. The level of detail and explanation made me really prepared - I knew I could handle everything in the kit because it was very straightforward from those that were ahead of me. I came back from that trip and placed the order. 18 months later I was done - but there were about 4 of those months "waiting for Skyview" - a problem that is now past us.

I can also attest to the ease of build the other guys here have been talking about. A couple hints.. one was already mentioned but I will second it.. for those of us who have never built a plane before the Homebuilt Help DVD's have been great. If for no other reason than to sanity check what I am reading in the plans and see someone actually do the steps in the plans they are valuable to me.

Second and this was something that Mitch from Vans told me when I test flew the -12 with him.. read ahead in the plans and make sure you follow the plans. If you think you have an idea of how to do something and it isn't consistent with the plans or something just looks obvious to you, there may very well be a reason why it isn't being done yet and reading ahead in the directions will help you out.

Carl

+1 for the homebuilt help dads
they are great, they should be shipped with the kit !

This is just my opinion, but to me it sounds like you've already made your decision. And that decision is a great one...obviously, you're going to have an excellent product with a -12 that will be much easier and quicker to build.

As far as I can see, the trade off will be that a Sonex is a stronger airframe (aerobatic) and cheaper to build. The RV-12 is a much more refined kit and probably more comfortable.

In the end, people love both. Look over a -12 kit then decide and get to work!

Perhaps I should have mentioned this in my original post, but Eagle's Nest thinks highly enough of the Homebuilt Help DVDs that we are including a set with every project. We believe that they will be a big help to the mentors, and the mentors can determine whether or not they show them to the builders. As an individual builder, I would use them. DO NOTE that they were done with the older avionics, and the wiring is our of date! We may work with HH to correct this, but it will take a while. Otherwise, they are great!

HELP Video's

videobobk said:

Perhaps I should have mentioned this in my original post, but Eagle's Nest thinks highly enough of the Homebuilt Help DVDs that we are including a set with every project. We believe that they will be a big help to the mentors, and the mentors can determine whether or not they show them to the builders. As an individual builder, I would use them. DO NOTE that they were done with the older avionics, and the wiring is our of date! We may work with HH to correct this, but it will take a while. Otherwise, they are great!

Click to expand...

Hey Rob would be Great to have up to date Wiring HELP Video ..! I have a complete set of Videos and loved them & I am still to Build my RV-12..!!

Mike_ExpressCT said:

This is just my opinion, but to me it sounds like you've already made your decision. And that decision is a great one...obviously, you're going to have an excellent product with a -12 that will be much easier and quicker to build.

As far as I can see, the trade off will be that a Sonex is a stronger airframe (aerobatic) and cheaper to build. The RV-12 is a much more refined kit and probably more comfortable.

In the end, people love both. Look over a -12 kit then decide and get to work!

Click to expand...

I have *mostly* made the decision. But it's hard to walk away from a 90% complete fuselage and complete tail that's I've already poured over 600hrs on. I also have to convince myself that I don't really care about aerobatics and never will. And of course the $10K plus I already have in the Sonex. If I can find a buyer I'll get some of that back, maybe half or a little more.

The good part is that I have don't so much fabrication on the Sonex that from what I see of the RV-12 kit it will be cake. I'm probably going to take a couple of weeks and mull it over, then order the tail kit so I can get a feel for whether it's the right move for me.

Here's a couple more questions:

1) Baggage is 50lb...how about space? Can two people fit enough soft bags in the baggage bay for an extended vacation?

2) MOGAS is not available in my area...how does the Rotax do on a exclusive diet of 100LL? Just more frequent oil changes, or are there durability or other maintenance concerns there?
The good part is that I have don't so much fabrication on the Sonex that from what I see of the RV-12 kit it will be cake. I'm probably going to take a couple of weeks and mull it over, then order the tail kit so I can get a feel for whether it's the right move for me.

Thanks!

MrMorden said:

I have *mostly* made the decision. But it's hard to walk away from a 90% complete fuselage and complete tail that's I've already poured over 600hrs on. I also have to convince myself that I don't really care about aerobatics and never will. And of course the $10K plus I already have in the Sonex. If I can find a buyer I'll get some of that back, maybe half or a little more.

The good part is that I have don't so much fabrication on the Sonex that from what I see of the RV-12 kit it will be cake. I'm probably going to take a couple of weeks and mull it over, then order the tail kit so I can get a feel for whether it's the right move for me.

Here's a couple more questions:

1) Baggage is 50lb...how about space? Can two people fit enough soft bags in the baggage bay for an extended vacation?

2) MOGAS is not available in my area...how does the Rotax do on a exclusive diet of 100LL? Just more frequent oil changes, or are there durability or other maintenance concerns there?
The good part is that I have don't so much fabrication on the Sonex that from what I see of the RV-12 kit it will be cake. I'm probably going to take a couple of weeks and mull it over, then order the tail kit so I can get a feel for whether it's the right move for me.

Thanks!

Click to expand...

1. That all depends on what you are carrying.

2. Do not use 100ll all the time. You will need to bring mogas to the airport if you don't have it there. There are many mechanical reason not to use 100ll all the time. Cross country and occasional use, no problem.

Geico266 said:

2. Do not use 100ll all the time. You will need to bring mogas to the airport if you don't have it there. There are many mechanical reason not to use 100ll all the time. Cross country and occasional use, no problem.

Click to expand...

This to me is a problem. MOGAS is just not all that common, whereas 100LL is everywhere. If I have to cart gas to the airport every time I want to fly, that's a major inconvenience, and there is no ethanol-free mogas in this area, so I'd be stuck with 10% ethanol blends and all the problems that causes.

Well, there are a few difficult parts in this build. Probably nothing serious as you have struggled with a much more complicated and demanding kit, but I feel I should mention it.
The longerons were a big struggle for a lot of builders, There is one tool you should have, that turns a nightmare intoa 30 minutes job. Search for longerons in the RV-12 forum and find the longeron dies that someone here offers. I did one without and one with this tool. It's like day and night.
Others had a struglle with getting the fuel tank leak-free. A problem I didn't have, so I can't really comment on that other than that it worked for me.
The thing I so far dislike most about the build is the canopy skirt. I'm not a fan of fiberglass work per se and that probably contributes to it. Fortunately it's not a lot of area that has to bet covered, but I still wish there was a prefabbed skirts to just glue or rivet on.

Baggage: The area covers more than the fuel tank holds, so I'd guess you have about 30-35 gallons of storage area behind the left seat if you fill it not higher than the edge of the rear window.

100LL: Every Rotax owner I know is having this problem and all of them came up with a fuel solution that involves bringing Autogas to the air port. That's just something to live with until MOGAS becomes widely available. There are tractor outlets that sell fuel storage that you can trailer to the hangar that include a pump and a hose with nozzle for easy fueling. There are plastic containers with carts that you can roll to the airplane that hold enough fuel for refueling the -12. Considering the exorbitant price of the engine, I'd pay close attention to avoid 100LL as the lead is no friend of the Rotax at all. If you go for cross-country make sure you use a semi-synthetic oil and no fully synthetic one. The latter won't help dissolve the lead and it falls out and could deposit easily inside the engine.
Don't worry about the 10% ethanol in the -12. The fuel system and the engine can handle it. Get some spare o-rings before you take the carbs off as they might expand from the ethanol and might not fit back in once they were removed.

MacPara said:

I still wish there was a prefabbed skirts to just glue or rivet on.

Click to expand...

That is already available.
from the same people that are developing the Viking engine.
I don't have the link handy, but you can google viking engine and then browse around their site until you find it.
I think they want $250 ish

MrMorden said:

This to me is a problem. MOGAS is just not all that common, whereas 100LL is everywhere. If I have to cart gas to the airport every time I want to fly, that's a major inconvenience, and there is no ethanol-free mogas in this area, so I'd be stuck with 10% ethanol blends and all the problems that causes.

Click to expand...

10% ethanol is NOT a problem for the rotax engine.

getting MoGas to the airport is not trouble, just get a 20 gal can in your car and fillip at the station on the way to the airport.

if you go cross country you can refill with 100ll for the return journey
but I suspect most of your flights will be local and you'll mostly fillup at home.

See this thread for fueling options.
http://www.vansairforce.com/community/showthread.php?t=5730
I got a flo-fast system like Tony's and it is working out great. I have two 5-gal cans I fill at the service station and take back/forth to the hangar to replenish the 15-gal flo-fast. You could get two 15-gal flofast tanks and swap the pump on them but 15x6=90 pounds to handle in and out of a pickup bed. A 5 gallon tank is OK to load directly into the fuel port on the RV12 but more would be pretty heavy-awkward.

Just another comment - -

filling at an airport with a high flow pump can cause problems also. Without a separate breather/vent, you can get a splash-back and have it running down the side and especially on the rear window. I use the fast-flow can, and it works great. I am in good enough shape, that lifting it is not bad for me. It will dump 5 - 6 gallons in about 1 minute, getting light very fast. I get about 19 gallons at a time when I go to the station, and keep it in the rear of my pickup. I do not have to go to the station every time that way. I use a Mr. Funnel and fill my fast-flow can. I feel it gives one more step in protection from water etc., in the fuel. You get to watch it flow thru the filter into the fast-flow can.

John Bender

tim walter said:

That is already available.
from the same people that are developing the Viking engine.
I don't have the link handy, but you can google viking engine and then browse around their site until you find it.
I think they want $250 ish

Click to expand...

I know. Just not sure about the ELSA status when using that. So I meant "from Van's" in my previous statement ....

MacPara said:

I know. Just not sure about the ELSA status when using that. So I meant "from Van's" in my previous statement ....

Click to expand...

The ELSA is a lot more flexible than EAB actually.
I think you can have 100% of the airframe assembled by 3rd parties as long as it all conforms to the plans and you must buy all the kit parts from Vans.
The fairing consists of builder supplied materials, so do not need to be purchased from vans.

Hauling Mogas is a pain but the $20.00 or more savings a fill-up makes it worth while. Avgas is $5.30 / gal at KARM - Mogas 93 oct. is $3.99 / gal.

IJS

Gary

Guys.. just another data point in the 100LL/Mogas discussion. I agree it would be better to burn Mogas as frequently as possible. With that said.. the flight school where I learned has several 912 powered planes. Some of them burn mostly Mogas at one airport and three of the others burn only 100LL. They both are running fine. The one made it to TBO of 2000 hours before being swapped out and sold with no issues at all on only 100LL for 2000 hours. 25 hour oil changes and regular maintenance and it did just fine. There is another one with nearly 1000 hours and another with over 300 all 100LL only and they are also doing fine. I am not saying it isn't an issue and I know Mogas is preferable, just throwing this empirical data point out there. FWIW I burn 100LL about 90% of the time in my 912 as well and it is doing well also.

Carl

So you keep track of fuel burns, and alter the oil changes to somewhere between the two intervals, or just use 25 hrs if you burn any 100ll?

I now have 400 hours on the 912 in New Blue. This engine was originally in the yellow proof of concept RV-12 so it had 200 hours on it when I got it. This engine has been fed nothing but 100LL for the last 360 hours. The only noted item we've found is that when the carbs were rebuilt at the 500 hr TT mark, the blue residue from the 100LL had built up sufficiently on the slides to prevent smooth movement. Result was improper and out of balance fuel mixtures yielding a not-so-smooth running engine. It never missed a beat. It just kind of 'growled' at you between app 2800 and 3900 RPMs. Once cleaned, smooth engine operation was restored over the entire RPM range.

Thanks for the info on fuels, it sounds like With 25hr oil changes and a little more diligent maintenance, a steady diet of 100LL is not a problem for the Rotax.

It sounds to me like you don't really like building all that much and are looking for an easier way out. There are builders and there are flyers, you have to decide which one you are. If you are truely trying to decide between the RV-12 and a Sonex and are leaning towards the RV only because of the easier build then why not just go out and buy a completed Sonex? You can easily buy a sonex on barnstormers with the Jabiru 3300 for well under what the RV-12 is going to cost you by the time you are done. You could probably even buy two Sonex with the Aerovee engines for the same cost as one RV-12. Now if you have other reasons for not wanting a Sonex such as IFR capability, baggage space, or cockpit size then by all means go the RV-12 route. To just go to the RV because of a quicker build time doesn't make much sense. You can be up and flying next week in a Sonex if you buy one already complete. It doesn't get much quicker than that.

Keith

Sit in the Sonex then sit in the -12 and you will easily make the decision. Better yet, sit in each one with a passenger. Compare everything in the cockpit, brakes, stick, FLAP HANDLE, etc. The Sonex with the VW is a bit anemic on performance, on the other hand a Sonex with the Jab 6 cyl. is an impressive performer. Overall, they are not that comparable. The -12 is a very refined aircraft in comparison.

True but a completed RV-12 is two to three times the cost of a completed Sonex. It is sort of like comparing a Hyundai to a Lexus. They both can drive on the same road but are far different in cost and comfort features. It all goes back to what you flying mission is. Long cross country with some IFR capability and alot of baggag capacity go for the RV-12. Flying around the local area doing aerobatics with only an occasional VFR cross country then go for the Sonex.

Keith

Part of the cost comparison is invalid, IF you build the RV12 as EAB like the Sonex, and don't think you need the $14,000 avionics nor the $29,000 engine, neither of which the Sonex has, costs are more aligned and the extra size of the RV12 cockpit comes at a far lesser price. Still cannot fly upside down in the RV12 though, darn it..

If you use the AeroShell Sport Plus 4 then you can burn 100LL (in excess of the 30% mark) and change the oil and filter at 50 hours (plugs at 100 hrs).

This is stated in the Rotax SI-912-016 'Suitable Operating Fluids'.

At work we operated a Tecnam P2006T for 400 hrs plus a P2002-JF single for 200 hrs purely on 100LL with AeroShell Sport Plus 4 and found absolutely no problems.

I just change every 25 hours for oil, 50 for filter and 100 for plugs and have no issues. The guy I have working on it does many 912's for flight schools in the area so it is just second nature for him.

DonFromTX said:

So you keep track of fuel burns, and alter the oil changes to somewhere between the two intervals, or just use 25 hrs if you burn any 100ll?

Click to expand...

aerofurb said:

If you use the AeroShell Sport Plus 4 then you can burn 100LL (in excess of the 30% mark) and change the oil and filter at 50 hours (plugs at 100 hrs).

This is stated in the Rotax SI-912-016 'Suitable Operating Fluids'.

At work we operated a Tecnam P2006T for 400 hrs plus a P2002-JF single for 200 hrs purely on 100LL with AeroShell Sport Plus 4 and found absolutely no problems.

Click to expand...

Rotax recently updated SI-912-016.
They now specifically recommend that oil changes be done every 25 hrs if operating exclusively on 100 LL.
Everything I have heard in Rotax training is that the problems (if you are going to have any) start showing up at 600-800 hrs. If you burn a lot of 100 LL, I think the gear box inspection is specified to be done sooner (for that reason).