RV-12 with a converted VW (Revmaster or Aerovee)

[PabloSniper]

First of all, hello everyone, this is my first post here. I live in the extreme south of Brazil, almost on the border with Uruguay and Argentina.
Like most people here, I am passionate about aviation. But it is an expensive passion.
I am very interested in building an RV-12, but I intend to reduce costs as much as possible.
The VW engine is very abundant here, and I was doing some research and found two companies that specialize in converting VW engines for aviation.
Revmaster and Aerovee.
The version that caught my attention the most was the 100hp Aerovee Turbo.
It weighs a little more than a Rotax, but weighs less than a Jabiru 3300.
I see that many people are skeptical about changing engines, but I am looking for honest opinions, without passion.

 

[titanhank]

Mismatched for the airframe. If you want a vw powered airplane, build a sonex instead.

 

[BoydBirchler]

I think you would need to change the position of the turbo to keep the engine close enough to the firewall for center of gravity purposes. That may be a difficult proposition given the small cowl depth on the RV12.

 

[Mel]

Another disadvantage of the VW is the power curve. Move the RPMs back slightly and you start losing power at quite a rate.

I personally don't think the VW is a good engine for the RV -12. When I built my "scratch built" bi-plane, I looked at the VW and chose the Jabiru over it.

If you want an alternative, take a look at the UL Power 260i or 260is engines.

 

[Mike S]

Pablo, welcome to VAF

 

[David Paule]

These engines spin the propeller at much higher RPM than the Rotax does, so prop efficiency will be significantly less.

Dave

 

[rv6ator]

It is likely you can aquire the VW engine cheaper than a Rotax. However as others have stated, you are opening up a whole new can of worms in trying to adapt the VW engine to an RV-12 airframe. Engine mount, cowling, exhaust, gearbox and whatever else will need to be addressed. I know of several people who have tried the Subaru engine in their RV's, only to eventually replace it with a Lycoming due to a variety of problems.

 

[PabloSniper]

It is likely you can aquire the VW engine cheaper than a Rotax. However as others have stated, you are opening up a whole new can of worms in trying to adapt the VW engine to an RV-12 airframe. Engine mount, cowling, exhaust, gearbox and whatever else will need to be addressed. I know of several people who have tried the Subaru engine in their RV's, only to eventually replace it with a Lycoming due to a variety of problems.

I understand and appreciate your opinion, as well as that of everyone who commented here in the thread.
Can I ask one more question?
A friend has a Rotax 912 80Hp for sale. And it has a very interesting price for the brazilian reality.
Would the RV-12 be able to fly with 80hp?
Is there already an RV-12 with this engine?

Pablo, welcome to VAF

Thank you very much my dear!

 

[N8DAV8R]

If you want an alternative, take a look at the UL Power 260i or 260is engines.

But be ready to sort through some W&B compromises. The engine seems to be a good alternative but this is an aspect that UL RV-12 builders like to avoid, or lie about.

 

[Mel]

But be ready to sort through some W&B compromises. The engine seems to be a good alternative but this is an aspect that UL RV-12 builders like to avoid, or lie about.

The UL260i weighs in at 161 lbs. installed, including exhaust and oil. Almost identical to the Rotax 912is by the time you add cooling system and coolant.

 

[N8DAV8R]

The UL260i weighs in at 161 lbs. installed, including exhaust and oil. Almost identical to the Rotax 912is by the time you add cooling system and coolant.

Meanwhile we both know there is more to W&B than the weight spec as provided by the engine mfg.

I don't mean to discourage anyone or kick up a too much dust. I'm close enough to a situation to know that some funny numbers get thrown around in this context, but ultimately it's not my business. I would just recommend a builder going with UL keeps an open mind about this compromise, there are reasons it could be worthwhile.

 

[Mel]

I don't disagree with researching all data. OTOH, I have a UL350 on my current project and can assure you that the engine,
ignition coils, voltage regulator, etc. weigh just what the manufacturer states.

 

[N8DAV8R]

I don't disagree with researching all data. OTOH, I have a UL350 on my current project and can assure you that the engine,
ignition coils, voltage regulator, etc. weigh just what the manufacturer states.

Great! Is it an RV-12? If so I hope you will post your W&B, along with the full engine/prop configuration when you have it all done. It will be valuable for the community, and you are a well known and trusted resource so it will go a long way.

The B part of W&B is important too.

 

[Mel]

Great! Is it an RV-12? If so I hope you will post your W&B, along with the full engine/prop configuration when you have it all done. It will be valuable for the community, and you are a well known and trusted resource so it will go a long way.

The B part of W&B is important too.

Not an RV-12.

 

[PabloSniper]

I have already found a more economical solution, which will not require adaptation.

 

[Baron71]

I understand and appreciate your opinion, as well as that of everyone who commented here in the thread.
Can I ask one more question?
A friend has a Rotax 912 80Hp for sale. And it has a very interesting price for the brazilian reality.
Would the RV-12 be able to fly with 80hp?
Is there already an RV-12 with this engine?

Thank you very much my dear!

While I can’t answer your question on 80hp, I know someone who got a cheap 912is with 100 hp for his RV-12is. But as @rv6ator said, there is a lot of other stuff that needed to be adjusted for the ROTAX OEM 912is to fit. This guy estimated it to have taken him four to five times as long as the regular kit install.

 

[N8DAV8R]

View attachment 87271

I have already found a more economical solution, which will not require adaptation.

Without making any comment as to the quality control and reliability expectation of the Rotax clones; From an aircraft configuration perspective I would expect that to be a better alternative than the others you presented. The fact is that the RV-12 is designed very tightly to the light sport specifications and a particular engine package. The Zongsens would not deviate significantly from that.

The hangup you are going to hear from RV-12 builders/owners comes from getting an intuitive sense of how much of the airplane is designed around the engine and how deviations lead to consequences. Other airframes may have a wider margin with respect to engine choices and expected performance. Rotax clones are probably worth a serious look if you insist on an alternative.

 

[PabloSniper]

Without making any comment as to the quality control and reliability expectation of the Rotax clones; From an aircraft configuration perspective I would expect that to be a better alternative than the others you presented. The fact is that the RV-12 is designed very tightly to the light sport specifications and a particular engine package. The Zongsens would not deviate significantly from that.

The hangup you are going to hear from RV-12 builders/owners comes from getting an intuitive sense of how much of the airplane is designed around the engine and how deviations lead to consequences. Other airframes may have a wider margin with respect to engine choices and expected performance. Rotax clones are probably worth a serious look if you insist on an alternative.

The Chinese from Zonsen were already producing parts for the Austrians from Rotax before the patent expired.
I don't see how a 100% faithful copy would cause problems.

 

[edhunter]

I’d second the “build a sonex “ comment above….

 

[N8DAV8R]

The Chinese from Zonsen were already producing parts for the Austrians from Rotax before the patent expired.
I don't see how a 100% faithful copy would cause problems.

That is a level of comfort for you to decide. You may know more than me with respect to where parts were made and the controls on the assembly line. ZS could be better, or could be worse. Rotax themselves have not had a great year when it comes to QC so I'm not making any arguments.

As I understand things, the real market for those engines is to meet a demand in markets with export controls, primarily in UAV applications with limited life expectancy for other reasons. Of course, that could just be dramatic FUD.

Like someone else said, if your goal is to use the VW variants a Sonex is probably the best choice. Just build that. If you really want an RV-12, stick with the Rotax or a clone.

 

[Mich48041]

Also consider the Zenith 750 STOL or Cruiser. They are not designed around a specific engine.

 

[Capt]

Being experimental you can fit whatever engine you desire, BUT straying away from the ‘acceptable” most common power plant (912/100HP) may very well work against you when it comes time to sell it, good luck

 

[PabloSniper]

If possible, a moderator could close the topic, as I have already opted for the Chinese clone of Rotax.