sprucemoose said:Chase, I'm curious why you consider the sliding canopy and wing tanks to be advantages? The tip-up canopy makes ingress and out-gress easier, and the fuse-mounted tank makes the folding wings possible. Since LSAs tend to be aimed at older, medical-less pilots who are less dexterous, I think the advantage is to the tipper. If you're young and spry, then the bigger, wing tanks might be an advantage, but then again, the young and spry are not the target market for the RV-12.
Don't worry and just let the Rotax run. It is a proven engine with a good (although not perfect) service record. It makes a happy song about 5200 RPM and will make 75% power there all day, sipping 5 gal/hr or MoGas or 100LL. Yes, the gearbox is new and different and not in use on the average Lyc / TCM motor. However, the same was once true of things like fuel injection and electronic ignition.elfiero said:1. I'll never be comfortable twisting any aircraft engine to 5000+ rpm- ever. Continental and Lycoming make nice little engines(around 100 hp) that will live almost forever without the silly gearcase. The S-19 was originally designed around a O-235 ( I called and asked).
Yes! Motorcycles, boats, snowmobiles, spec racecars (e.g., Formula Mazda, where the engines are sealed and often go several years before rebuilds), etc. The issue isn't the RPM - witness F1 cars, who get 20,000 RPM out of their 2.4l V8s - but how the engine is designed. Rotax seems to have done their engineering correctly.elfiero said:Two questions immeadiately come to mind.
1. Can anyone name another application where an internal combustion engine buzzes along at or above 5000rpm for hours on end every time you use it for 20+ years? any small displacement conventional aircraft engine lasts that long at 2500 rpm with relatively little maintanence.
No. This is somewhat of a problem, but not a huge one. Let me try and explain:elfiero said:2. Can you pick up used jugs or ignition components at just about anyplace you can land for a Rotex?
Geico266 said:How do they do it? One reason the clyinder walls are "ceramic" coated. Wear is minimal when the correct oil is used, and the engine is serviced properly. The tolorances are very close. This is a tight, well engineered engine, with a long history of dependable service.
elfiero said:Yes, I fully understand the Rotex is a "completely engineered powerplant system" and when it has been around as long as the continental "c" series, I'll have a great respect for it. But just like todays cars, the average joe might as well not even open the hood 'cause there's nothing for you to do under there anyways. The "real aircraft engines" can be modified for more HP relatively easily and cheaply as compared to the rotex which is basiclly impossible to change and is producing the maximum HP it can ever produce when you take it out of the box. Also, is it even possible to hang an electriclly operated prop on a rotex? I don't think that silly gearbox would like that very much. What if the all important "factory" exhaust won't fit your particular setup? I've heard that if you mess with the pipes the "little engine that could" don't like it much. I guess I'm just one of those A&Ps that won't accept the french/canadian motor until it gets rammed down my throat. If you really want to understand it, take a vacation in quebec and see how you're treated as an American- it'll give you a whole new outlook on this little engine.
gmcjetpilot said:Has the Rans S-19 flown? What is the specs. My guess is it may be nice but my money is on the RV12 flying: a little faster, carry a little more, a little further, off of shorter runways. Could be wrong, but if you want a RV12 or S-19 than by golly build it. You do know the company support and community you get with the RV product. I am sure Rans is a good company, but unless they have one flying than I would wait. It looks heavier and draggier. Regardless of spec, until they build it and fly it than its a guess.
I urge you spend a few hours looking at and getting to know the engine. It is uncomplicated and easy to work on. There are few maintenance requirements, and the most complicated system is the dual carbs - they need to have the throttle travel adjusted periodically. This is checked using a pair of vacuum gauges.elfiero said:Yes, I fully understand the Rotex is a "completely engineered powerplant system" and when it has been around as long as the continental "c" series, I'll have a great respect for it. But just like todays cars, the average joe might as well not even open the hood 'cause there's nothing for you to do under there anyways. The "real aircraft engines" can be modified for more HP relatively easily and cheaply as compared to the rotex which is basiclly impossible to change and is producing the maximum HP it can ever produce when you take it out of the box. Also, is it even possible to hang an electriclly operated prop on a rotex? I don't think that silly gearbox would like that very much.
With all due respect it's only 74 cubic-inch engine. It is, as was said, maxed out. There is only so much you can do with so few CUBES.rv6ejguy said:Any engine can be modded for more power. The Rotax is no exception.
gmcjetpilot said:Other strikes against the Rotax in no particular order:
Single ignition?
I put a question mark after it, and "a strike against YOU" is kind of personal and not really productive. What does that mean? I make mistakes and I'm wrong all the time. I guess I was thinking of the Subaru. Oh-oops, my mistake, never mind.JimLogajan said:Strictly speaking, "Single ignition" is a strike against you since the Rotax 912 is a dual ignition engine.
As noted elsewhere, the 912S uses dual electronic ignition with dual lighting coils built into the alternator (no battery necessary). Also, max continuous RPM is 5500.gmcjetpilot said:With all due respect it's only 74 cubic-inch engine. It is, as was said, maxed out. There is only so much you can do with so few CUBES.
Yes you can make more power but its already turning 6 or 7 grand. THERE AIN'T NO REPLACEMENT FOR DISPLACEMENT.
rv6ejguy said:I don't really like the dry sump system. Why, why would they do this? Heavier, bulkier and their suction system is potentially scary for cold weather ops- no scavenge stage either. Jabiru did this better with a wet sump. Pre-heat is recommended. And of course the twin carbs. They work but are dated.
Look ALL good points and not bashing Rotax. My only point, which I do think is valid, the LSA weight limit is restrictive to the point it limits the useful engines you can use to basically the smaller (lighter) Rotax. That is frustrating. Also low powered planes are not safer. On "press day" at AOPA a Press official pilot, flying a new LSA solo crashed because it did not get out of ground effect. I think the engine was down on power. You need all those cylinders.the_other_dougreeves said:As noted elsewhere, the 912S uses dual electronic ignition with dual lighting coils built into the alternator (no battery necessary). Also, max continuous RPM is 5500.
More displacement does not guarantee reliability. Witness the number of Nextel Cup "stock" car engines that blow vs F1 engines. Both are naturally aspirated V8s that make about 800Hp. F1 cars are 2.4L - "cup" cars are 5.9L.
Yes, there is not much growth potential in the 912S to go beyond 100Hp without turbocharging (in which case it becomes a 914). Not a big deal, IMHO.
gmcjetpilot said:I am going to guess that the tiny Rotax turns you on.
I agree - the 600kg / 1,320 lb LSA limit effectives limits you to the Rotax and maybe Jabiru engines.gmcjetpilot said:Look ALL good points and not bashing Rotax. My only point, which I do think is valid, the LSA weight limit is restrictive to the point it limits the useful engines you can use to basically the smaller (lighter) Rotax.
Actually, one of the neat things about the 912 is the combination of water and air cooling. Heads are water cooled, cylinders air cooled. If you loose the coolant loop, you can still use partial power for some time without overheating. You can still shock cool a 912, but it's harder to do with the water cooling.gmcjetpilot said:The Rotax is designed for high RPM and has the water cooling, which is nice in a light weight package. No argument. However the air cooled engine is simpler.
Most LSA aren't that aerodynamic, I agree - there's just not a huge need for make the airframe slippery if you're limited to 120kt. However, if you use the 2-blade prop adjusted to 5500 RPM in cruise (or use a adjustable pitch prop), the CT makes 130kt on 5 to 5.5gph. Shame we can't do that in the US - guess we might hurt our little fingies.gmcjetpilot said:As far as Miles Per Gallon, I doubt many LSA's can hold a candle or beat a (I)O235/O320, RV-9. Why? Because you takea RV9 and fly at 130 mph you will almost make fuel. I think van played around with max endurance speed and he was down to 2 or 3 gal an hour.
Two words: No medical. If you don't have one (or don't want to renew because you think you'll get denied), then all the performance in the world doesn't matter.gmcjetpilot said:Why would you build a RV12 when you can build a RV8/7/9, which have more performance and can be build for less (used O235, O290, O320).
gmcjetpilot said:Why would you build a RV12 when you can build a RV8/7/9, which have more performance and can be build for less (used O235, O290, O320)... Now you have a 150hp RV-9 that can GO fast and if you want, fly at 130 mph and use fuel like moped.
Dittowestexflyboy said:From the performance perspective, I absolutely agree. From the builder perspective, my intuition says the RV-12 will have a much higher completion rate. In other words RV-12 will be a heck of a lot easier to build and, for many builders, will be flying months to years sooner with acceptable performance concessions.
Chase Snodgrass
Presidio, TX
http://flybigbend.com
ABSOLUTELYrv72004 said:If Vans could make the quick build 7,8 or 9 a bit "quicker" it may well become very viable to go the above route. Surely there must be some meat in the 51% rule to allow more work done by the factory.
Lets be honest, apart from the few out there ,the majority wants a quicker build .
Maybe all in favour could sign a petition begging Vans to push the 51% rule to its limits. I would gladly pay extra to get me in the air faster. O yes , my 7 is flying but it sure would be nice to quickly build a 8.EJ
gmcjetpilot said:Again another 50, 100 or 150 lbs to the LSA weight limit would cut into Rotax's business. I think the weight was made to cut out certified planes. WHY? Politics?
Well said.RV6junkie said:Most people that buy an LSA will use the same criteria that they use to buy a car; looks, value, economy, performance and a strong recommendation from a friend.
If they ever see this thread, or ones like it - they will be sure to stay clear of aviation. Because according to us, there is something wrong with everything.
RV6junkie said:Interesting debates:
Lycoming/Continental vs. Rotax
1320 pounds vs 1500 pounds
120 kts vs 123 kts
The one thing that most of you are overlooking is that Sport Pilot wasn't designed for YOU. The intent of the Sport Pilot rating and LSA is to get more people - people without prior knowledge of aviation - into aviation.
Joe/Jane Average doesn't have an alliance to a particular engine manufacturer (chances are they've heard of Rotax, not Lycoming), doesn't care about the 10 kts because 120 already sounds real fast, and really doesn't care about how things have always been done - because for them it's ALL new.
They just want to do a little flying without having to get a second mortgage. And 30 hours of flying to get a license sounds a lot easier than 50 to 80 hours. Sport Pilot is the path of least resistance. And that's a good thing.
If you are participating in this conversation, consider yourself part of the lunatic-fringe of aviation. We care about everything - even the things that we shouldn't.
Most people that buy an LSA will use the same criteria that they use to buy a car; looks, value, economy, performance and a strong recommendation from a friend.
If they ever see this thread, or ones like it - they will be sure to stay clear of aviation. Because according to us, there is something wrong with everything.
Interesting that you suggest that on a LSA thread. Remember that there is the E-LSA, which is not subject to the 51% rule - the factory can provide the kit in just about any stage of completion. There are downsides, i.e., little deviation allowed from the kit, but build times can be WAY reduced with the e-LSA. If you could reduce completion times in the 200 hour range with standardized FWF assemblies and pre-fab wiring harnesses, you'd get a lot more interest. Rans has done this with the S-12XL, and it wouldn't surprise me to see Randy go the e-LSA route with the S-6, S-7 and/or S-12 designs.rv72004 said:If Vans could make the quick build 7,8 or 9 a bit "quicker" it may well become very viable to go the above route. Surely there must be some meat in the 51% rule to allow more work done by the factory.
Lets be honest, apart from the few out there ,the majority wants a quicker build.
Phyrcooler said:Ditto
Which is why I am considering an RV-12 as apposed to an RV-9. I don't want to start a 5 year RV project at this point in my life - but hope to be able to crank out an RV-12 or something comparable in about 18 months.
Mike Armstrong said:Rv6ejguy, your on a roll, seriously, your making alot of sence here and folks should go back and re-read your posts in this thread.