Roger Lee Posted July 19, 2014 Report Share Posted July 19, 2014 Hi Andy, CTLSi as high as 857 lbs. Link to comment Share on other sites More sharing options...
Acensor Posted July 20, 2014 Author Report Share Posted July 20, 2014 100hamburger wrote, in part -- "...The older planes also use generators, the CTLSi has dual alternators...." I didn't know about dual alternators in the CTLSi .... are they in the new Rotax engine or outboard of the engine? A possible minor correction: As far as I know all of the older 912 Rotax engines and even the new ones (except maybe the fuel injected one which I'm not familiar with) have always had single internal _alternators_ for the charging system.. not "generators." Technically they are all "generators" as they all generate electrical power. There are DC-generators and AC-generators. By common usage "AC-generator" got reduced to "alternator" leaving the word "generator" to mean (at least when talking cars and aircraft and other internal combustion vehicles) a DC-generator. (But, FWIW, if you walk into a large generating station of a regional power utility all their generators are AC generators and there they don't call them "alternators.") In fact I don't believe any vehicle since maybe 1970 or earlier has used a generator at all. Generators are DC output and were used in cars and many aircraft engine installations prior to about 1966. Even many of those older aircraft were later refitted with alternators. DC-generators were abandoned in favor of alternators (short of "AC-generators") mostly because an AC current is easier to regulate and give appropriate charge level regardless of engine RPM. ------------- Finally FWIW: A significant _potential_ DISadvantage of fuel injection is that electrical injectors take somewhat significant electrical power. In a carb engine, even if the alternator fails there's usually in the battery enough power to run avionics and the trivial power to the plugs for many hours. (With traditional mags you can literally fly for months with a dead battery AND dead alternator.) But if there are electrical fuel injectors drawing power once the alternator quits you may have only 20 minutes .... 90 if you're lucky. So, come to think of it, that reality is kind of consistent with, and would explain why, they're putting put duel alternators in with the fuel injected version. That way there are three sources of electrical power (one battery, two alternators) and the bet being places is all three won't fail at the same time. Alex Link to comment Share on other sites More sharing options...
Anticept Posted July 20, 2014 Report Share Posted July 20, 2014 The CTLSi uses two alternators, which are of similar design to the 912ULS. They use a permanent magnet flywheel, and Rotax calls them "magneto-generators". The smaller magneto-generator has 2 sets of coils to drive the left and right ignition lanes. If the generator fails, then main aircraft power can be applied to continue driving the system, and finally battery power if it got that bad (very unlikely to get that bad without a total engine failure). The reason that it's not a DC-generator is because they still spin the magnets, and not the coils, therefore they do not need to use a commutator on what would have been the armature. Instead, they invert the traditional system build, and use permanent magnets instead of a field winding. Basically, the stator, in their design, is internal, while the permanent magnet flywheel (rotor) is external. The Ducati "voltage regulators" used by Rotax aren't really traditional regulators. They effectively just try to prevent too much current from flowing. As Chanik said here on the forum in an older post, they don't do a very good job (I think he said they use current switching methods), and that's the source of the tremendous electrical noise present in rotax installations. Link to comment Share on other sites More sharing options...
Doug G. Posted July 20, 2014 Report Share Posted July 20, 2014 100dollarhamberger wrote..."Since you are looking at specifics the older planes do require manual manipulation of fuel mixture." I am not certain what you are saying here, but there is no manual mixture control on any Rotax 912 I know of. Link to comment Share on other sites More sharing options...
WmInce Posted July 20, 2014 Report Share Posted July 20, 2014 100dollarhamberger wrote..."Since you are looking at specifics the older planes do require manual manipulation of fuel mixture." I am not certain what you are saying here, but there is no manual mixture control on any Rotax 912 I know of. Maybe he was referring to the choke. Link to comment Share on other sites More sharing options...
Doug G. Posted July 20, 2014 Report Share Posted July 20, 2014 What choke? We have a carburetor's starting circuit. Kinda like lane A and lane B, but through the carb. Link to comment Share on other sites More sharing options...
Anticept Posted July 20, 2014 Report Share Posted July 20, 2014 Mine has a choke lever. Link to comment Share on other sites More sharing options...
FastEddieB Posted July 20, 2014 Report Share Posted July 20, 2014 Minor point, but a "choke" is a specific device that blocks the flow of air into the carb to provide a richer mixture for starting. Doug is right - BING carbs do not have chokes per sé. In spite of the fact that the lever or knob in the cockpit may be labeled "CHOKE", it is connected to a rotary device within the carb that provides a richer mixture by providing more fuel, not less air. This arrangement has been found on BMW airhead motorcycles since about 1970, relevant since that carb was the nexus of the carbs on the ROTAX. I have a photo of the inner workings I'll post shortly. That said... On the one hand, carbs are fine - they have a century or more of refinement behind them and have evolved into remarkably adept devices for mixing fuel and air. On the other hand, fuel injection has proven itself to be a superior concept, and is the future. It has the ability to manage fuel/air ratios much more precisely, with the promise of better efficiency and lower emissions. Still, early implementations of fuel injection schemes can be problematical - early adopters may face "tweaking" as the manufacturer gets in more data. I think we're seeing that pattern with the FI ROTAX. And the realistic among us have to admit that the carbs on the ROTAX have proven to be a bit of a "Achille's heel", being a but too finicky - especially regarding tiny debris finding it's way to the jets. I would opt for fuel injection in my Sky Arrow in a heartbeat - the only caveat being I would not give up useful load to get it.* *My Sky Arrow weighed in at a porky 861 lbs empty, only recently reduced by about 10lbs via a switch to a lighter lithium ion battery. Link to comment Share on other sites More sharing options...
FastEddieB Posted July 20, 2014 Report Share Posted July 20, 2014 As promised, a digital photo* I took when overhauling the BING carbs on my 1990 BMW R100GS/PD: I took that photo to ensure that I got the orientation of the disk right on reassembly - I think its possible to get it 180º off. I think its the teardrop shaped cutout that controls how much extra fuel to pour into the engine when the "choke" is on. And this shows how nearly identical the carbs were to what we have: BMW airheads were plagued with the same "crap blocking the jets" issue that our planes have. Hence many put inline filters right before the carbs, as seen in the photo. *Historical note: that first photo was taken with a Sony Mavica camera that stored its images on a 1.4k floppy disk. How far we've come! Link to comment Share on other sites More sharing options...
Anticept Posted July 20, 2014 Report Share Posted July 20, 2014 I had not actually sat down and opened the carbs yet (no training on rotax carbs), but it doesn't surprise me that they use an enrichment valve instead of a choke. Link to comment Share on other sites More sharing options...
Roger Lee Posted July 20, 2014 Report Share Posted July 20, 2014 The carb en-richer and butterfly in the throat have center punch marks for correct orientation. If you know what to look for it is hard to mess them up. The screws in the butterfly need to be ground down before removal. They are peened over and will strip the treads if you try to just muscle them out. The new screws need to be peened back in place correctly to keep them from coming loose and going into the engine. The carb piston fixation screw that holds the main jet needle in place needs to be heated to remove it or you may twist the head off this soft aluminum screw. It isn't pretty after that. If you have not been trained or at least been shown how to do the complete rebuild you can mess them up. If you need carbs rebuilt I can do it with a one day turn around and always have kits on hand. I get them from all over the country. Link to comment Share on other sites More sharing options...
Jacques Posted July 20, 2014 Report Share Posted July 20, 2014 get the full video on ROAN .. Link to comment Share on other sites More sharing options...
Roger Lee Posted July 20, 2014 Report Share Posted July 20, 2014 They leave a couple of details and tips out. They even tell you it is supplemental only. Link to comment Share on other sites More sharing options...
Anticept Posted July 21, 2014 Report Share Posted July 21, 2014 I've got a local guy who has been doing these carbs for years. I'll get the rotax training and start doing carbs myself, but right now I'm pretty busy just keeping up with the general inspections and maintenance. Link to comment Share on other sites More sharing options...
Acensor Posted July 21, 2014 Author Report Share Posted July 21, 2014 Hi Anticept, Thanks for the detailed education on the multiple alternators in the 912. More odd and complex than I knew, and reassuring to know how unlikely a total failure of the ignition system is with that redundancy. You also wrote --- "...The Ducati "voltage regulators" used by Rotax aren't really traditional regulators. They effectively just try to prevent too much current from flowing. As Chanik said here on the forum in an older post, they don't do a very good job (I think he said they use current switching methods), and that's the source of the tremendous electrical noise present in rotax installations." Re that a couple of comments: 1) We did have a lot of electrical noise on the 912 on our Skyranger that cost us a lot of headaches and cash trying to get acceptable radio performance. Our avionics guy put about $250 worth of noise filter on the alternator output. And half a dozen other tedious and expensive avionics-guy-type tricks to improve matters. All helped, but not enough. In our case we finally trashed the old MicroAir transceiver .... seems it either was terminally defective or the design simply couldn't cope with the level of electrical noise out of a 912. Replaced it with a MGL V6 which we're very happy with. 2) Our panel has a switch that turns off the main alternator. The previous owner/builder placarded it "On when engine on, Off when Engine Off." Don't know what he had in mind by having that switch there, but it make for a good preflight (or for that matter in-flight) test of the alternator. You can clearly see that if you start the engine with it off the battery is getting no alternator input as the voltmeter sits at about 12 volts, then climbs to about 14 volts when switch is activated. If I flipped it on and the voltmeter stayed at 12 volts I'd know I was likely about to takeoff with a non-op charging system. It's also useful in that if the charging system went screwy and started spewing even more than normal radio static one ccould temporarily turn it off to make and receive some radio communications. My question is.... Is this on-off switch for the charging system a oddity of our 912 installation or has anyone seen anything like that on other 912 installations? Alex Link to comment Share on other sites More sharing options...
WmInce Posted July 21, 2014 Report Share Posted July 21, 2014 The CTLSi has the dual alternators. Installed with the 912iS engine. The other models don't have that feature. Also, the CTLSi with the fuel injected 912iS has the Lane A Lane B solid state ignition system. And the dual Dynon Skyviews etc. The CTLSi also has a different battery, its the lighter Li Ion battery. Here are all the major differences in the CTLSi versus the older models. http://flightdesignusa.com/aircraft/ctls/ Where does that fit into, "Advise a buyer on a 2004 2K vs a 2006 SW... both nice birds?" Link to comment Share on other sites More sharing options...
FastEddieB Posted July 22, 2014 Report Share Posted July 22, 2014 My question is.... Is this on-off switch for the charging system a oddity of our 912 installation or has anyone seen anything like that on other 912 installations?AlexVirtually every small plane I've flown has had an alternator switch/switches of some description. Usually, but not always, a "split master", where one side is BAT and one side is ALT. That's what my Sky Arrow with a 912 has. I'd think there must always be a way to get a malfunctioningalternator offline - either a switch or a breaker. Link to comment Share on other sites More sharing options...
Anticept Posted July 22, 2014 Report Share Posted July 22, 2014 If I flipped it on and the voltmeter stayed at 12 volts I'd know I was likely about to takeoff with a non-op charging system. It's also useful in that if the charging system went screwy and started spewing even more than normal radio static one ccould temporarily turn it off to make and receive some radio communications. My question is.... Is this on-off switch for the charging system a oddity of our 912 installation or has anyone seen anything like that on other 912 installations? Alex It's not unique to the rotax. Some planes have an integrated switch that connects both power and alternator, like my mooney for example. But, it also has an alternator breaker. Our warrior has a separate Battery Master and Alternator Master switch. It's more common to see the separate switches in older aircraft, than one unified switch. Alternators on standard aircraft are required to have a pilot resettable breaker or switch too: 14 CFR 23.1351 ( c ) (3) Automatic means must be provided to prevent damage to any generator/alternator and adverse effects on the airplane electrical system due to reverse current. A means must also be provided to disconnect each generator/alternator from the battery and other generators/alternators. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 22, 2014 Report Share Posted July 22, 2014 I wish the CTSW had switches or switch breakers instead of the push/pull breakers for battery and generator. The push/pull units seem a little fragile and chintzy to me. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted July 22, 2014 Report Share Posted July 22, 2014 I wish the CTSW had switches or switch breakers instead of the push/pull breakers for battery and generator. The push/pull units seem a little fragile and chintzy to me. Mine came with toggles, they look more correct to my eye. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 22, 2014 Report Share Posted July 22, 2014 Mine came with toggles, they look more correct to my eye. I think toggles or rockers would be much nicer. Lighted rockers would be slick to tell you if they are on or not. Link to comment Share on other sites More sharing options...
Anticept Posted July 22, 2014 Report Share Posted July 22, 2014 We replaced the switches on one of our CTLS with equally rated switch breakers with Dave's approval. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 22, 2014 Report Share Posted July 22, 2014 Thinking about it some more, it might be easier to trip a toggle accidentally when using the center panel controls than the push/pull breakers. I think I remember CT saying he did that once or twice. A low profile rocker might be better, but I don't think there are rocker-style switch breakers. Link to comment Share on other sites More sharing options...
Anticept Posted July 22, 2014 Report Share Posted July 22, 2014 I honestly prefer the breakers. Even if they are cheap feeling, they don't cost much to replace, and ours lasted for almost 2000 hours of on-off flight training. Link to comment Share on other sites More sharing options...
WmInce Posted July 22, 2014 Report Share Posted July 22, 2014 While on the subject of switches, breakers, etc . . . . . . I don't like the location of the flap lever/switch. IMHO, it is too close to the throttle lever and ignition key switch. I know there is a purpose for that proximity, but I still don't like it. Anybody here ever inadvertently move the flap lever/switch to an unintended position? I have learned from my short experience with the CT, to pay closer attention to that flap lever and its annunciator. Link to comment Share on other sites More sharing options...
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