Ed Cesnalis Posted August 31, 2013 Report Share Posted August 31, 2013 ... I also think it is a translation issue. I think that it is a limit as to how far off of vertical it can be mounted. There is no ambiguity in the Installation manual. The limit is for the differential between effective vertical and current bank angle, the limit is 40° Effective vertical for that saw is effected by both the mounting and the bank angle. Rotax qualifies their limitation by saying: The engine design is for a non-aerobatic, fixed wing tractor or pusher type configuration with the oil return port in the optimum position. With this condition the engine is properly lubricated in all flight profiles. The saw does not qualify for this limitation. This limitation could not be for " how far off of vertical it can be mounted." because that brings another variable into it. If your 912 was mounted at 40° from vertical in your CT then your differential would be 80° in one direction and 0° in the other. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted August 31, 2013 Report Share Posted August 31, 2013 This limitations is misnamed, its not as much a bank limitation as it is a tilt limitation because pitch factors in with the same weight as bank. 1° increase in pitch gets you 1° closer to the limitation just as 1° increase in bank gets you 1° closer to the 40° differential limitation. If you used a more complex method that considered a tilted engine limitation you could apply it to an engine that is drooped duel to compressed motor mounts. If the engine drooped 1° you would be 1° closer to the limitation ( pitch down only ) Link to comment Share on other sites More sharing options...
Tom Baker Posted August 31, 2013 Report Share Posted August 31, 2013 CT, I think we are in the same book, but different pages. The limit has to do with the forces acting on the engine. No more than 40° from the effect of gravity on the engine. This really has nothing to do with the bank angle of the airplane, rather the forces being applied to the engine. 40° in a big slip could excede the limits, but 135° bank with positive loading might not. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted August 31, 2013 Report Share Posted August 31, 2013 Tom, The question is how to interpret the 40° Bank Angle Limitation, the OMs are not clear on their definition of deviation but the installation manuals are quite clear. There is only one page to look to, the one that provides the definitions and engineering, this one from the installation manual: The section name from the installation manual is: 12.Banking of plane deviation from the effective vertical therefore it is about banking of the plane ( including pitching ). Neither of your examples qualify for the limitation, the big slip and 135° examples violate the limitations requirement that the bank be stabilized and without acceleration. I'm not disagreeing with you I'm just saying that the limitation is based on deviation from effective vertical and 60 degrees bank, level pitch does qualify for effective vertical. Link to comment Share on other sites More sharing options...
Tom Baker Posted August 31, 2013 Report Share Posted August 31, 2013 Tom, The question is how to interpret the 40° Bank Angle Limitation, the OMs are not clear on their definition of deviation but the installation manuals are quite clear. There is only one page to look to, the one that provides the definitions and engineering, this one from the installation manual: The section name from the installation manual is: 12.Banking of plane deviation from the effective vertical therefore it is about banking of the plane ( including pitching ). Neither of your examples qualify for the limitation, the big slip and 135° examples violate the limitations requirement that the bank be stabilized and without acceleration. I'm not disagreeing with you I'm just saying that the limitation is based on deviation from effective vertical and 60 degrees bank, level pitch does qualify for effective vertical. If you go back and look at my post I am talking about the forces applied to the engine in relation to the engines vertical axis. It is about what the engine feels and not its physical position in space. That would be deviation from effective vertical. If you had an airplane with enough rudder authority you could possibly skid around with wings level hard enough to create the side force needed to exceed the limits. That is why I said a hard slip might exceed the limits while a 135° bank with a positive pull might not. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted August 31, 2013 Report Share Posted August 31, 2013 If you go back and look at my post I am talking about the forces applied to the engine in relation to the engines vertical axis. It is about what the engine feels and not its physical position in space. That would be deviation from effective vertical... Tom, once again I agree with your assertions. What the engine feels can be a deviation from effective vertical but those conditions should be outside of the discussion because the discussion is about the meaning of the limitation. Rotax had to find a way to rule them out in order to use a fixed number for a max deviation from effective vertical. If you do what Rotax did in their definition and limit it to stable un-accelerated flight then the sum of all forces acting upon it defines the effective vertical. The deviation would be zero As Andy pointed out in the beginning 60 degree turns are permissible, its necessary to see that a 60 degree turn does not violate the 40 degree limitation because the deviation from effective vertical is zero when stable and not accelerating. Link to comment Share on other sites More sharing options...
Tom Baker Posted August 31, 2013 Report Share Posted August 31, 2013 Its all about the vector of force being applied to the engine. The resultant focre should not exceed 40° from the vertical axis of the motor. That is what the picture shows. The point I am trying to get accross is not that a 60° bank turn exceeds the limit, but that a 60° bank while not turnig would. That is why I said it is not the bank angle, but rather the force being applied. Link to comment Share on other sites More sharing options...
Doug G. Posted September 1, 2013 Author Report Share Posted September 1, 2013 So now we need to get Dynon to come up with an AOD indicator. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted September 1, 2013 Report Share Posted September 1, 2013 I'm guessing if you got your engine in an extreme attitude long enough for oil to not get to the bearings and pistons, you'd have a lot bigger fish to fry than worrying about engine damage... Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted September 1, 2013 Report Share Posted September 1, 2013 Any attitude that the CT can maintain is within the limitation. If you get negative the nose will fall through. I don't know how steep the CT can bank, I demonstrated the steepest turn that I could during my last BFR but when the CFI asked me what bank angle that was I couldn't tell him. At my max bank I can't read my bank angle. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted February 22, 2016 Report Share Posted February 22, 2016 Resurrecting a zombie thread...the last we heard Roger was going to ask Rotax, be we never heard his answer! I'm suddenly curious because Sonex Aircraft just added Rotax support for their airplanes. The entire Sonex line is rated for Sportsman-level aerobatics (+6g/-4g) -- I'm wondering how that would work with Rotax engines. In reality almost all the maneuvers in a Sonex will be at positive-g so it shouldn't matter much. But are Rotax 912 engines suitable for mild aerobatics (rolls, loops, spins, wingovers, etc)? Link to comment Share on other sites More sharing options...
CT4ME Posted February 22, 2016 Report Share Posted February 22, 2016 Link to comment Share on other sites More sharing options...
Anticept Posted February 22, 2016 Report Share Posted February 22, 2016 Yeah this is an old thread! Bank angle doesn't matter as long as it's coordinated, but as roger said, it's probably a rotax CYA. Max bank in a CT is 60, unless you get approvals for aerobatics to go beyond that! Link to comment Share on other sites More sharing options...
Roger Lee Posted February 22, 2016 Report Share Posted February 22, 2016 Max bank in a Rotax engine is 40 degrees and it's in the Operator's manual. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted February 22, 2016 Report Share Posted February 22, 2016 Max bank in a Rotax engine is 40 degrees and it's in the Operator's manual. So steep turns per the FAA are prohibited?!? Link to comment Share on other sites More sharing options...
Anticept Posted February 22, 2016 Report Share Posted February 22, 2016 Only if Flight Design prohibits it. The whole thing is certified as one unit, even if they didn't produce the engine. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted February 23, 2016 Report Share Posted February 23, 2016 Only if Flight Design prohibits it. The whole thing is certified as one unit, even if they didn't produce the engine. I get that, but nobody wants to trash their engine by exceeding a limitation, regardless of what the airplane manufacturer says. 40° seems insanely limiting...you can't even take a checkride in an airplane that can't do 45° turns. So if a manufacturer put in their POH "abide by all engine manufacturer limitations", then the airplane is pretty useless for training. There has to be more to this story. Link to comment Share on other sites More sharing options...
Anticept Posted February 23, 2016 Report Share Posted February 23, 2016 Fortunately, FD put a limit of 60 degrees in their POH! :-) As said, I think it's just a rotax CYA. I can't think of a single reason why the hell the engine would care as long as you are coordinated, and aren't trying to pull 235 G's or some such ridiculousness. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted February 23, 2016 Report Share Posted February 23, 2016 Fortunately, FD put a limit of 60 degrees in their POH! :-) As said, I think it's just a rotax CYA. I can't think of a single reason why the hell the engine would care as long as you are coordinated, and aren't trying to pull 235 G's or some such ridiculousness. I agree, if coordinated everything stays oriented up/down from its perspective. It's just an odd artifact that you don't see with other engine manufacturers. As I mentioned, the reason I asked is because of the change of the Sonex to support the Rotax and UL Power (previously it was VW or Jabiru only). I think the Rotax could be an ideal engine for that airplane at 40-50lb less than a VW or Jabiru 3300. But it wouldn't make sense if you could not exploit the aerobatic capabilities of the airplane with the Rotax installed. If we really think of it as a coordination limit, then most maneuvers would be fine. A 1g barrel roll would be fine, but an aileron roll would not. I don't think a Sonex can do a true aileron roll anyway. Loops, spins, and other light aerobatics should not be a problem. Link to comment Share on other sites More sharing options...
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