Is it possible to fit a rotax engine?

[Bin Huang]

The rotax 912 is very popular these days, the shp is good too, for it is similar to 0-200, both 100hp. If you want more hp, then you have rotax 915, with 135 hp. The PROs of using rotax engine would be it can operate on autogas, and it's a more modern engine.

But I could hardly find anyone adapted rotax on a long ez on the internet, anyone know if it is possible to do so?

The only issue I could think of is the lighter weight of the rotax, and a custom made engine mount is probably needed too, any other issue?

 

[Kent Ashton]

If you use the search function above, you will get more info than a couple of replies will give you.  Search " Varieze Rotax " at the top of the page.  When the results come back select "Varieze AND Rotax" at the top of the search results which will find both terms.   There are a number of threads on this topic.

Also try a Google Verbatim search for Varieze and Rotax.  That will also bring up various discussions on other sites   https://www.google.com/webhp?tbs=li:1

Edited June 10, 2020 by Kent Ashton

[Justin]

The Rotax engine range is amazing, but in my view, the UL390 series makes the most sense if you want a modern (fuel injected with FADEC) engine with a bit more power. Some people have put O-320s in EZs. They are heavier than the O-235 , and I hear people need to add weight up front to maintain the CG position. The UL390 is about the same weight as the O-235, and has variants ranging from 140hp to 160hp. Its torque lies between that of the O-235 and the O-320. Of course, a new engine mount design is required for the UL Power engines.

[Bin Huang]

On 6/10/2020 at 5:35 PM, Justin said:

The Rotax engine range is amazing, but in my view, the UL390 series makes the most sense if you want a modern (fuel injected with FADEC) engine with a bit more power. Some people have put O-320s in EZs. They are heavier than the O-235 , and I hear people need to add weight up front to maintain the CG position. The UL390 is about the same weight as the O-235, and has variants ranging from 140hp to 160hp. Its torque lies between that of the O-235 and the O-320. Of course, a new engine mount design is required for the UL Power engines.

Yes, I prefer FADEC engine, cause they are more fuel efficient and easy to use. The PRO of rotax is their lighter weight,  if handled properly, may gives you extra pounds of useful loads.

[Marc Zeitlin]

2 hours ago, Bin Huang said:

Yes, I prefer FADEC engine, cause they are more fuel efficient and easy to use.

Easier to "use", yes. Please provide evidence of FADEC piston engines being more fuel efficient than a manually adjusted fuel injection engine. Thanks.

[Bin Huang]

18 hours ago, Marc Zeitlin said:

Easier to "use", yes. Please provide evidence of FADEC piston engines being more fuel efficient than a manually adjusted fuel injection engine. Thanks.

I mean FADEC engine is more fuel efficient than those engine which require manually adjust mixture. This is only a general point, cause there are more than one engine in each category, and the efficiency of an engine depend on many aspect of an engine, and it certainly depend on the Engine Control Unit algorithm in the FADEC engine.

I remember I saw a graph that compare fuel efficiency of rotax 915 is (A FEDEC engine) and those older types, like lycoming 0-325 etc. But I can't find it now, although it is more like a claim than evidence.

I believe my claim on the fuel efficiency is valid, just think there is no reason a properly programmed Engine Control Unit couldn't outperform a man, cause the computer monitor and adjust the parameter of the engine multiple times per second, a man at best level, one time in several minutes. (Actually, some pilot claim they ignore the mixture setting when they shouldn't)

[Mark Wiygul]

If the LongEZ is out of weight balance because the engine is too light, one would just move the engine father rear of the firewall to restore proper balance? I'm guessing at that.  It seems that the Rotax 912-iS (fuel injected) would  be a great option for someone attempting to achieve the ultimate fuel economy.  I believe it is equal to o-200 in HP, which is the recommended engine that delivers the minimum HP for the LongEZ).  The Rotax 912-iS can deliver 100HP of takeoff power for 5 minutes, then must be throttled back to 80%.  It sips automobile gas at cruise more than any other engine that might be possible for the LongEZ. And, the pilot will not have to worry about carb-heat or fuel-mixture, which have been the source of pilot accidents at least in other airplanes.  The engine also has a 2000hour lifespan before it must be replaced.  The cons include more inconveniences on preflight like having to "burp" the engine to check oil.  And, a LOT of people on the internet talk poorly of Rotax.  

Edited April 19, 2021 by Mark Wiygul
grammer must be corrected

[Kent Ashton]

20 minutes ago, Mark Wiygul said:

The Rotax 912-iS can deliver 100HP of takeoff power for 5 minutes, then must be throttled back to 80%.  It sips automobile gas at cruise more than any other engine that might be possible for the LongEZ.

100 hp is not enough.  150-160 is a good hp for the EZ.  125 was barely adequate (but I never flew the O-235 versions) and people fly them heavier than Burt envisioned .  There would be times on a hot day, high field elevation or shortish runway when you would be sweating Tabasco sauce wondering if you can get off the ground. 🙂  Also if you move the engine aft, the prop might be close to the runway during rotation and landing.   Some people are using the ULPower engines but check the prices.  It's hard to beat a used/rebuilt O-320.  The cost of avgas is not that great compared to hangars and insurance; there's where the money goes.

[Mark Wiygul]

I'm just learning about the LongEZ (and Varieze).  I love the design!! Thanks for the reply

[zolotiyeruki]

A Rotax 915 might be a better option, with 150-ish horsepower.  With a pusher, you have to be careful of prop strikes if you move the engine further from the firewall, as Kent mentioned.  Tractor aircraft don't get off easy, either--you have to account for the impact of a longer nose on the aerodynamic stability of your airplane, too.  It's probably better to try and manage the cg with a lighter engine by moving avionics and such aft as much as possible.

[Mark Wiygul]

It looks like Lycoming engines are by far and away the most popular for the LongEZ.  It's really hard to find example of anything else except Lycoming.  Mogas might have ethanol and I've read that the acholol will eat away at the original plans fuel tanks.  I think the engine accessory systems are also harder to custom install on other engines.  The original plans, I believe, warned against the Continental O-200 because of great difficulties getting it all hooked up.  (I wonder if that ever changed)  Still, I haven't heard of a single person with a LongEZ O-200 (probably the low HP output too).  I wonder matching prop to engines is a big difficulty to get it right for the LongEZ. I've read that the prop needs to be long because of turbulence hitting the center of the prop, causing it to "swat" at the air.  But farther out from the prop (with a long prop) then the airflow is smooth, and the problem is gone.  With Rotax engines, they have a gear-box drive system because the RPM is so high, to otherwise slow the prop down.  It has a clutch in the gear-box that "protects the prop" from prop strikes.  That sounds like a good thing with the LongEZ, but maybe the prop "swatting" at the air in the center burns the gearbox clutch up?  (Do the wheel pants help?  I've read they slow the plane down.  Are there alternatives to protect the prop without all the glory of wheel pants?) I'm not a mechanic, so i might be using poor terminology there.  One other thing, of course I've been googling Horsepower and engine prices and fuel economy and figuring out which engine does what, but I've noticed HUGE differences in engine prices, even for the same model.  I know some are rebuilt, and others are brand new, but still I see enormous price differences googling aircraft engines between 100 and 200 horsepower, even for the same model.  I wonder if some of the prices are "installed by a mechanic" and others are "here you go, put it in yourself" varieties?  Those are just a few more thoughts I had on engines on LongEZ.  If anyone has any thoughts about this for the LongEZ or the VarieEZ, please comment.  Thanks.  

Edited April 22, 2021 by Mark Wiygul
grammer

[Kent Ashton]

Wow, lots of stuff there.   Wheel pants are needed.   Any prop strike is a disaster but in the canards it is more a problem of FOD into the prop.   Yes, a new lycoming is expensive but a salvage engine may be reasonable and an owner rebuild of a runout engine is quite doable.   The major prop builders generally know what prop will work with your HP

There  are lots of builder sites for the canards.    For a start try Ary Glantz.   http://www.aryjglantz.com/p/blog-page.html?m=0

       Or do a google image search for “long-ez” plus any other term and it will show lots of builder photos.    

[Gigante]

Almost everyone has gone either the 320/360 rute looking for more horsies (160/180+) and empty weights close to the 1,000 lbs mark . These are fast birds but need a runway suitable for an F16 . I don’t think that’s what Burt had in mind when he designed it in the 70s  , I am considering going in the other direction I have a 912 ULS I have rebuilt  with the Edge 1484 big bore and camshaft , this will make the 912 a 120hp engine together with the MT variable speed prop she should perform as well as 150hp in regards to relative efficiency not to mention I suspect it can be built just under 650lbs ... yes the 915is would be nice but $50,000 for an engine is a little much ... any ideas ? 
 

[Marc Zeitlin]

50 minutes ago, Gigante said:

Almost everyone has gone either the 320/360 rute looking for more horsies (160/180+) and empty weights close to the 1,000 lbs mark . These are fast birds but need a runway suitable for an F16...

None of that is correct.

About 1/2 of the Long-EZ's out there are using 320's. There are a few 360's (maybe 5%) and the rest are 235's (with a smattering of 290's and other random stuff thrown in there). Empty weights of the O-235 models tend to be 850 - 900 lb, and the O-360's tend to be 900 - 975. There are 1000 lb. LE's out there - generally with O-360's and loaded with other stuff (including a lot of fill). While I understand that the reference to F-16's is hyperbole, I regularly fly my COZY MKIV (essentially the same performance as an O-320 Long-EZ - maybe a bit less, depending) out of 2000 ft strips at Sea Level, when at 1600 - 1800 lb. GW.

50 minutes ago, Gigante said:

I am considering going in the other direction I have a 912 ULS I have rebuilt  with the Edge 1484 big bore and camshaft , this will make the 912 a 120hp engine together with the MT variable speed prop she should perform as well as 150hp in regards to relative efficiency not to mention I suspect it can be built just under 650lbs ... yes the 915is would be nice but $50,000 for an engine is a little much ... any ideas ? 

If you can get 120 HP from a 912, that should perform reasonably well - about like the 115 HP O-235. I'm not a fan of VS or CS props - there's just no need for the extra weight and complexity on a Long-EZ, just to save 200 ft. on the takeoff roll (and you'll give up speed on the top end). But it'll work. Not nearly as well as the 150/160 HP O-320, but like the O-235, as I said.

I've inspected close to 40 or so different Long-EZ's (CI's or Pre-Buys). I've never seen one under 800 lb., much less even close to 700 lb. You're dreaming if you think you can build one that weighs 650 lb. Get it down to 750 - 800 lb. and you'll have done a hell of a job.

[macleodm3]

On 6/12/2020 at 4:58 PM, Bin Huang said:

I believe my claim on the fuel efficiency is valid, just think there is no reason a properly programmed Engine Control Unit couldn't outperform a man, cause the computer monitor and adjust the parameter of the engine multiple times per second, a man at best level, one time in several minutes. 

The EZ family of aircraft are very efficient, and the group that flies them tend to LOVE taking advantage of all available efficiencies.  When you properly equip your Lycoming, you can fly lean of peak (LOP) for peak efficiency.  Most (perhaps all?) FADEC solutions don't run the engine lean of peak... so as I understand it, its pretty easy for an attentive pilot to run the Lycoming more efficiently than a computer running any engine in an EZ.  Now, if you have a computer that can run the engine LOP perhaps it could beat the typical EZ pilot.

[Kent Ashton]

On 6/12/2020 at 4:58 PM, Bin Huang said:

I believe my claim on the fuel efficiency is valid, just think there is no reason a properly programmed Engine Control Unit couldn't outperform a man, cause the computer monitor and adjust the parameter of the engine multiple times per second, a man at best level, one time in several minutes. (Actually, some pilot claim they ignore the mixture setting when they shouldn't)

The advantage of a manually-adjusted mixture is that the pilot has the choice of flying lean for low fuel consumption and range, or at a richer mixture and peak power for speed.  When a pilot understands that it only takes very simple controls to obtain those modes.  I have never flown a FADEC engine but I would think the computer, backup computer, and servos for an aircraft would be very expensive.  Wikipedia says:

Quote

• Full authority digital engine controls have no form of manual override available, placing full authority over the operating parameters of the engine in the hands of the computer. (see note)
  • If a total FADEC failure occurs, the engine fails. (see note)
  • Upon total FADEC failure, pilots have no manual controls for engine restart, throttle, or other functions. (see note)
  • Single point of failure risk can be mitigated with redundant FADECs (assuming that the failure is a random hardware failure and not the result of a design or manufacturing error, which may cause identical failures in all identical redundant components). (see note)
• High system complexity compared to hydromechanical, analogue or manual control systems
• High system development and validation effort due to the complexity
• Whereas in crisis (for example, imminent terrain contact), a non-FADEC engine can produce significantly more than its rated thrust, a FADEC engine will always operate within its limits. (see note)

Note: Most modern FADEC controlled aircraft engines (particularly those of the turboshaft variety) can be overridden and placed in manual mode, effectively countering most of the disadvantages on this list. Pilots should be very aware of where their manual override is located, because inadvertent engagement of the manual mode can lead to an overspeed of the engine.

 

[Justin]

I have had ECU controlled engines in fuel injected cars since the late 80s. None ever failed in any way.

If I get back to Open EZ and build, I would enjoy having no mixture controls in the cockpit. I would prefer the UL390 to any Rotax. It is direct drive, and has only air cooling, and you can see the engine when the cowl is off. The more powerful Rotax engines have a lot of complexity in their installations, and you can barely see the core of the engine with all the clobber on it. It is just my preference to keep it simple, and I do know that Rotax engines are exceptionally good, but I think their best engine is the 912. It has small frontal area and suits sleek ultralights, but not the EZ.

[Ratdog]

i have been searching high and low and asking on the facebook rutan site as well as here for any concrete info on the rotax 912 being used in a Variez.  There are lots of rumors but no one can even come up with a photo.  Trying to put a rotax into a Varieze would require lots of time and money trying to figure out how to mount it , How to cool it, and the proper prop.  With no flying examples it would not be easy .  It would be an ideal engine probably but the examples i see of it being used as a pusher the engine is not inside a cowl .   So you really dont know what will happen when you mount it backwards inside a cowl as far as CHT etc let alone how many props you would have to go through to find what works the best . 

[slk23]

21 hours ago, Ratdog said:

i have been searching high and low and asking on the facebook rutan site as well as here for any concrete info on the rotax 912 being used in a Variez.  There are lots of rumors but no one can even come up with a photo.  Trying to put a rotax into a Varieze would require lots of time and money trying to figure out how to mount it , How to cool it, and the proper prop.  With no flying examples it would not be easy .  It would be an ideal engine probably but the examples i see of it being used as a pusher the engine is not inside a cowl .   So you really dont know what will happen when you mount it backwards inside a cowl as far as CHT etc let alone how many props you would have to go through to find what works the best . 

 

Stefano Ferretti in Italy used a 912 turbo in his VariEze.  He wrote an article for the Jan. 2022 issue of Canard Aviation magazine (canardowners.com). 

 

Edited October 21, 2023 by slk23

[Ratdog]

Thanks .  looks like I found an 0200 B to put in mine.