I am not familiar at all with them. What is their dependability factor? More specifically if possible the Rotax 912-US? (Been looking at the Highlander http://www.justaircraft.com/page.php?13 )

Awesome plane for playing around.
Seems like a lot of cash but where else are you going to find a new plane that performs like that for the money.
Easy on fuel also. sure would be fun!

Terry, I been flying behind one for the last 600 hours (912 ULS) and it's made a believer out of me. After 40 years of Lycomings and Continetals I love it.

It likes auto gas, has a 100 hour oil change and is as smooth as silk. It uses less than 1 quart of oil between oil changes and burns about 4.3 gal/hr at cruise. Have had no maint. issues since new. I know probably about 30 others with similar experience.

As an A&P I was very interested in this new engine (to me) so I went to the factory school to get a better understanding of it. It's built like a watch! You'll like it.

Thousands and thousands of light sports rolling off the assembly line with that engine installed as standard equipment says something about it. My only issue with it is the cost. Close to 20K for the FWF for 100hp.. ouch.

Terry,
I am moving to McCall ID in the next several months and as soon as I get my shop set up there I will be starting on a Highlander build. I am plannning to build it with a Rotax 912 ULS as many others have.

I'm not sure if you know about the Just Aircraft forum or not, but here is the link.

http://www.wingsforum.com/viewforum.php?f=218

There is a guy named Paul in Orwigsburg, PA who just finished building up a really nice one with Rotax912 ULS. User b1x4ngb. He's very active with posts and pics and I'm sure he'd be more than willing to answer any questions you may have. Maybe you could get lucky and have him take you up in it too as it looks like you might live relatively close to each other.

AvidFlyer wrote:.....My only issue with it is the cost. Close to 20K for the FWF for 100hp.. ouch.

I don't know, buy a new Continental O-200 with accessories & mount & I bet it would be over $20K.
The Rotax 912 seems to have a fine track record, but it's awful busy for my tastes- dual carbs, water cooling, reduction drive. I kinda like the looks of the Jabiru 2200 (4 cyl, 80 hp) & 3300 (6 cyl, 120 hp)-- the main drawback would seem to be the higher operating rpm which requires a shorter prop than usual.
The Jabiru engines sure look good as far as fit and finish go. I think a Kitfox or Highlander with the Jabiru 3300 would be a real rocket ship.

Eric

Okay, these engines have the upsides, Jabiru nicely made, Rotax smooth running. Here's some editorial balance . . .

The Jabiru engine makes a lot of radio frequency interferance (RFI). One owner has even resorted to shutting off the engine and gliding while talking with ATC.

I owned a 914 (turbo charged and intercooled). These engines don't like 100LL (think plugged oil galleries from the lead and sticking valves). Have an absolutely incredible number of SB's (Rotax seems to crank one out every week or two), and, at least on the certified versions, are thus a pain in terms of maintenance due to all the CYA stuff. I suppose in the non-certified versions this isn't so much a problem.

(note my engine was a '97, so much of the problems (cracked cases, carb flanges, sticking turbo wastegates, foaming oil causing valve train problems with the hydraulic lifters etc) will have been solved. Engine was smooth running, but I sure wouldn't trade it for the Lyc in my current plane, even if it was 180 hp.

bumper

For some reason the Air Force academy had a fleet of those little plastic airplanes with Rotax engines. The Rotax engines were removed and replaced with Continentals. Of course the aircraft were later sold and replaced by what I don't know, But it seems like the Air Force tried the plastic airplane / Rotax experiment and for some reason didn't like it.
I do think that the airplane powerplant thing has been stagnant for so long that anything new, even if it's better, will have a hard time being accepted as the mechanics out there are lazy and don't want to learn anything new.
I know it's just ignorance, but they just turn too many RPM's for me.

A64 I felt the same way about the RPM's. I'm used to a screaming two stroke rotax on my ultralights. I flew in a Kitfox with a 912 and expected a quiet smooth ride. We were cruising at 5800 rpms and it was just as loud or louder in the cockpit than a two stroke. The Jab is a direct drive and only runs at about 2800rpm. Lots of LSA's with that engine too.

Cessna originally announced their light sport was going to be Rotax powered and then backed off to the new lighter Continental O200. I suspect this had more to do with cost negotiations, and a dealer network already used to working on the traditional engines.

According to a guy that went to one of the Rotax seminars in Florida, there are flight schools getting 3000 hour life out of the Rotax by doing some conditional inspections after the normal 1500 hour TBO. It would be interesting to know how widespread that really is.

The Jabiroos look pretty nice. The early ones had some teething problems, but I haven't heard much lately, so they probably are working pretty well. While you can run them at 2800 rpm, I think 3300 is where you get max horse power.

A quick calculation of average piston speed of the Rotax at 5800 rpm shows that it is about 30% higher than a typical O235 at 2750 rpm. With the TBOs 1500 and 2000 hours, respectively, the life is very comparable.

Rotax is pretty specific about engine oil if you are running mostly 100LL. They want the oil change interval halved, and they want semi synthetic oil, not full synthetic, since the semi will keep the lead suspended better.

The Rotax has two carburetors, and it is very important to keep them syncronized or the engine will shake like a dog shitting peach pits. This also tears up the gearbox. Some owners have found this hard to keep adjusted, but I suspect it is more a function of a poor installation than a difficult of engine design.

With the Euro going so high, the Rotax has gotten awfully expensive. I paid $12K for my 912ULS in 2004, but I understand they are close to $20K now. The 115hp 914 turbo was $24K then, who knows now. This is a significant deterrent to many homebuilders.

I'm happy with my 912ULS, but if I needed a new engine today, I would definitely look around to see what new information was available.

tom

Anyone here had one overhauled? I wonder how the cost compares to an O-200.

I know of many guys who are flying the 912 series engines and love them. I myself have the 914 (like Bumper...turboed and intercooled and love it...mine is a 2007 so all the issues he mentioned have been fixed). I have one buddy who put over 350 hours on his 912 ULS last year alone and has a TT of over 800 hours with not a single problem. My 914 is in a Kitfox Series 7 and it definitely is a rocket! I considered the Jabiru but opted for the rotax for the ability to swing a 72" prop...the Jabiru would have been limited to a 62" and I felt that would affect my climb performance too much.

I don't know about the 2-strokes but the 4 stroke Rotax engines are very will built and are extremely smooth.

By the way, the US military still flys all of its Predator drones on Rotax 914 engines.

When I was wrenching on a small fleet of DA-20s, they'd gone over to the Continental IO-240, which were very good engines. Extremely reliable, especially given their training role.
Before that, the fleet were Rotax powered Katanas, and the other mechanics didn't seem to like them much. I came after the switch, so don't have any experience with it, but the replacement was quite nice.

Darinh wrote:I don't know about the 2-strokes but the 4 stroke Rotax engines are very will built and are extremely smooth.

The 2-strokes are well-built engines also, extremely light, but come with all dangers of a 2-stroke. I'm a big fan of the fan-cooled 503, and if tuned and maintained properly they'll go for a long time, but the problem is that 2-stroke tuning can be such a misunderstood science, and the guys operating them often aren't the read-the-manual types.

Good oil, correct oil/fuel ratio, proper jetting, engine monitoring, and inspections will keep them humming till they simply start to get down on power from waning compression.

Even though I'm a Rotax fan, I don't think I'll ever be a fan of water cooling in aircraft engines.

Somebody with the real numbers correct me, but the two stroke Rotax engines are only good for 300 or 400 TBO. How come? My two stroke Johnson outboard has over 700 hours on it, and it still pulls great. The Johnson is water cooled, with a thermostat for temperature control, maybe that is it? I haven't had to do anything but preventive maintenance on it, and for 70hp, it is very light weight. The whole motor weights 258 pounds, and I bet 2/3 of that is not the engine part, but the drive stuff.
tom

Darinh wrote:By the way, the US military still flys all of its Predator drones on Rotax 914 engines.

Not all of them, Honeywell brought the G-10 back into production for the predator B. The -10 is of course a 1000 hp turbine, so I guess the B model is a little larger I don't have any idea what the average life span of a drone is, but I bet not many make it to TBO.

Savannah-Tom wrote:Somebody with the real numbers correct me, but the two stroke Rotax engines are only good for 300 or 400 TBO. How come?

Those numbers are right, and they are the numbers from the factory. My opinion is that it's VERY conservative. I've heard of guys putting 1200 hrs on them. I think Rotax knows their market and expect the engines to lead hard lives in the hands of garage tuners. There's really no technical reason that I can think of as to why the numbers would vary so much from the 4-stroke line other than the variability introduced by fuel/oil mixing. The max RPM values aren't that much higher (6,800 on the 503) than their 4-stroke big brothers (5,800 for the 912)

The 503 and 582 (the two engines I've played with while assisting in the overhaul) had needle bearings for both the main bearings and rod bearings. The 503 is piston ported while the 582 has a rotary valve. The newer models have dual electronic ignition instead of points.

Their simplicity and bombproof construction lends to a very simple and reliable engine, but I think the TBO numbers are a product of all the ways the Rotax engineers expect people to abuse the 2-strokes, i.e. overleaned fixed jetting, overleaned fuel/oil mixture, etc.

Almost all two strokes have needle bearings on both ends of the rods, but they do not see as good a lubrication as their four stroke cousins of course because there is not pressurized oil present, or even oil for that matter, it's a mix of fuel/oil.
But, most two stroke failures are not due to rod bearing failures as you might suspect, but rather piston failures. Usually overheating which leads either to seizure, scuffing or the piston top melts around the ring, siezing it and results in a loss of compression. Often this is from being run leaner than it should. To qoute my early 70's Husqvarna manual the engine should be jetted just lean of where it "four strokes". Unfortunately more power can be had if run leaner than that, but then you see the overheating and piston scuffing etc. Many two strokes have been destroyed in the search for more power. The joke used to be they run best just before they blow up .
FWIW the early Kawasakis 900's and 1000's had roller bearing cranks, technology left over from their two strokes, these cranks would last forever. I think the early Cosworth engines were needle bearings as well, but plain bearings are much more efficient and allow much higher RPM, with much less drag.
If it's done correctly liquid cooling is much superior to air cooled, actually most all liquid cooled engines are actually air cooled, what cools the radiator? Being liquid cooled allows a much more even temperature to be maintained which allows closer tolerences and greater efficiency, cleaner burning etc. I assume Zane, the engines you have experience with the cooling isn't done correctly?
I'm sure if a piston aircraft engine were to be designed today, it would be liquid cooled, liquid cooling has too many advantages to it.

Lot of great information being contributed here - thank you!

Keep it coming!

and

HAPPY NEW YEAR!

Neighbor Pete wrote:Terry,
I am moving to McCall ID in the next several months and as soon as I get my shop set up there I will be starting on a Highlander build. I am plannning to build it with a Rotax 912 ULS as many others have.

I'm not sure if you know about the Just Aircraft forum or not, but here is the link.

http://www.wingsforum.com/viewforum.php?f=218

Hey, let me know if you need any help building your plane. I don't really have any experience, but I can hold a wrench or whatever you need. Plus I always like to meet another aviator.