[nmontei]

I'm wondering if puting a gemini 100 (Jet A, 100hp) in a RV12 instead of the rotax would work? What i would really like to do is electric, but I'm not sure that is fesible yet.

Nick

 

[Peterk]

sure if you want to build it ex ambuilt but its not on the 51% list so proving your 51% is up to you. Van's himself has said that might be difficult. Right now they are marketing it as an ELSA which means you have to follow Van's direction (Rotax). After you have it certified you can switch engines if you like...as long as you stay within the operating limitations. Of course now you own two engines.

Pete

 

[todehnal]

Gemini 100

I'm wondering if puting a gemini 100 (Jet A, 100hp) in a RV12 instead of the rotax would work? What i would really like to do is electric, but I'm not sure that is fesible yet.

Nick

Actually, Van's folks seemed quite optomistic at Oshkosh about the RV-12 being built as EAB. As far as the Gemini 100 is concerned, I think the w&b, as well as the fit, are doable in an RV-12. In fact, it would probably be the easiest alternative engine for the Rorax. That is what the designers are trying to accomplish. My biggest concern is that I would like to see and hear it run, before making that committment. They talk a good talk and it looks great. I also like the idea of using Jet A instead of gasoline. Also, the Rotax doesn't like 100LL very well and Ethenol free auto gas is getting hard to find.

Tom

 

[Randy H]

You don't need ethanol free gas in the Rotax

Actually, Van's folks seemed quite optomistic at Oshkosh about the RV-12 being built as EAB. As far as the Gemini 100 is concerned, I think the w&b, as well as the fit, are doable in an RV-12. In fact, it would probably be the easiest alternative engine for the Rorax. That is what the designers are trying to accomplish. My biggest concern is that I would like to see and hear it run, before making that committment. They talk a good talk and it looks great. I also like the idea of using Jet A instead of gasoline. Also, the Rotax doesn't like 100LL very well and Ethenol free auto gas is getting hard to find.

Tom

I traded e-mails last year with the Rotax engineers in Austria. They said that they have tested the 912 with 5% ethanol and have found no problems. At the time they said that they intended to test it with as much as 20% ethanol.

 

[rv6ejguy]

Better wait until Gemini gets engines in production, proves that they last in the real world and stays in business for at least a few years so you don't end up with an orphan.

There hasn't been one new major piston engine maker to enter the market and be successful in the last decade without lots of problems in service. Jabiru may finally be there. I keep hoping some of these new engines will succeed but they invariably spend way too much in development and testing to ever make that money back and show a return afterwards at any reasonable price.

The Rotax works well, is proven, reliable, lightweight and has a decent servicing network. It will take a long time for any newbie company to accomplish all that.

 

[todehnal]

Ethanol in a Rotax

I traded e-mails last year with the Rotax engineers in Austria. They said that they have tested the 912 with 5% ethanol and have found no problems. At the time they said that they intended to test it with as much as 20% ethanol.

Right now, all that is approved in the 912 is 5%. That's a major problem for us USA folks, because just about all that we can find is 10% ethanol auto fuel. That drives us over to 100LL, with all of that lead and contamination, that is so unhealthy for the 912. Sure hope to see something in writing and official soon, that will support 10% ethanol usage in these engines!!!

This fuel issue is the only thing driving me to seek an alternative engine for my RV-12. Other than that, I think that it is a winner for the 12.

Tom

Tom

 

[N941WR]

Better wait until Gemini gets engines in production, proves that they last in the real world and stays in business for at least a few years so you don't end up with an orphan.

That's part of the problem, as I see it. How can a company survive for a few years if people don't buy and fly their engines.

Even us homebuilder types are just a little touchy when it comes to our engine selection.

It would be great if these people survive and the engine proves itself.

Jabiru and Rotec, both Australian engines, seem to be bucking the trend.

The Rotec was well received because it is a radial and there just wasn't/isn't anything else on the market, if you want a radial.
(BTW, I think an RV-8 with the 150 HP radial would look awesome! I might just perform well due to its light weight too.
Jabiru has really turned itself around. A number of the early engines had problems and didn't work out so good. Now they seem to have turned that around and have developed a good reputation.

I wounder how much money both of these companies have spent on R&D. It would surprise me if it came to even one million.

The Rotax works well, is proven, reliable, lightweight and has a decent servicing network. It will take a long time for any newbie company to accomplish all that.

I agree 100%, the Rotax is a great engine.

With luck some of these diesel engines will survive and flourish, as Rotec, Rotax, and Jabiru have.

 

[KThorp]

Pardon my ignorance, but why is it so difficult for A/C engine manufacturers to modify their engines to run on 10% ethanol?

Car engines have been doing this for years, right?

 

[the_other_dougreeves]

Right now, all that is approved in the 912 is 5%. That's a major problem for us USA folks, because just about all that we can find is 10% ethanol auto fuel. That drives us over to 100LL, with all of that lead and contamination, that is so unhealthy for the 912. Sure hope to see something in writing and official soon, that will support 10% ethanol usage in these engines!!!

This fuel issue is the only thing driving me to seek an alternative engine for my RV-12. Other than that, I think that it is a winner for the 12.

In the Dallas area, we consistently find that certain stations have more EtOH and others have less. We find 5% EtOH MoGas at, fortunately, a station that is close to our home base. 100LL and MoGas can be mixed in any percentage.

I also like to patronize FBOs that have 91 octane EtOH free MoGas. They are few and far between, but without our dollars, they're not going to carry the fuel.

However, we need to remember that leaded avgas is going away - it's just a question of when. 100LL accounts for about 30% of total US lead air emissions. We're going to see more MoGas or a unleaded 100LL replacement in the future.

TODR

 

[rv12iS-builder]

TODR (or other Rotax users),

If you run a 912 on 100LL exclusively, but change the oil every 25 hrs and use Decalin or TCP, would you still have problems with lead deposits?

 

[rvbuilder2002]

TODR (or other Rotax users),

If you run a 912 on 100LL exclusively, but change the oil every 25 hrs and use Decalin or TCP, would you still have problems with lead deposits?

Sort of...
It is acceptable for operation but it does require cleaning out the oil tank at scheduled intervals and there are issues with long term lead buildup in the gear box.

It is true that in writing Rotax only approves 5% Ethanol content but Lockwood has some extended operational experience (they have done internal inspections and overhauls on 10% operated engines). They say there is no noticeable difference compared to 5% and that it is still a much better fuel choice than extensive use of 100LL.

 

[the_other_dougreeves]

TODR (or other Rotax users),

If you run a 912 on 100LL exclusively, but change the oil every 25 hrs and use Decalin or TCP, would you still have problems with lead deposits?

You certainly will get lead build-up in the engine. The first item affected by lead is the gearbox. It has a 600 hour inspection requirement on it. Many gearboxes on engines running only 100LL make it to the 1800hr TBO and some don't. I gearbox overhaul with a complete new gear set costs about $4,000. However, you shouldn't need a complete new gear set unless there is some other sort of damage.

If you ran on 100LL only, I would expect to overhaul the gearbox at 1,000 hr; if you come out running beyond that, great, but budget it for it, maybe an extra $1/hr. (You're going to overhaul it at TBO anyway, so that's an extra $2000 every 2000 hours)

Our gearbox was overhauled at 200 hr by Rotax because of some bad gears that were installed at the factory - no charge to us for the overhaul, although we had some costs for removing and reinstalling it.

Anyway, yes, you can use 100LL without major problems, but it won't go as long between overhauls as an engine run on mogas.

TODR

 

[todehnal]

Ethanol Experience Reply

It is true that in writing Rotax only approves 5% Ethanol content but Lockwood has some extended operational experience (they have done internal inspections and overhauls on 10% operated engines). They say there is no noticeable difference compared to 5% and that it is still a much better fuel choice than extensive use of 100LL.

Thanks Scott!! That's exciting information. Just knowing that someone has been there and done that is satisfying, particularly when it comes from a respected source.

The Rotax 912 choice is sounding better and better

Tom