skippydiesel

RF , Your logical presentation is heading in the right direction however some possible holes (I stand to be corrected): "Prop spins a bit slower on the Rotax, that's worth a few % in efficiency. The Rotax prop spins a lot slower (a little over 2100 rpm at 75% cruise, to the Jab (guess) around 2700 rpm) and is not only more efficient it tends to be quieter - important in Europe now and in Australia in the future (fly neighbourly) Rotax torque 128 NM @5000 rpm gives it an advantage in TO/Climb out. Rotax runs lean in cruise. Jab runs compatratively rich, costing perhaps 5 to 10% in fuel " - My current Rotax aircraft seems to be delivering about 15 L/hr, 5200 rpm at 130 knots indicated - how would a Jab compare? AT 2000 hours, Rotax has had a gearbox service @ 1000h maybe about a grand, - 1200 hrs if run on ULP Both have had two sets of plugs. - will need to check but I think Rotax recomend 200 hr/set of plugs = 10 sets Both have had 1 set of hoses - Rotax rubbers replaced every 5 years of service and likely at least twice as much hose involved - must be more costly than Jab Both have had 40 x oil and filter changes. - Rotax recomend an oil change very 100 hrs (when run on ULP) so this would be 20 oil changes, compared with Jab X 80? (at today's prices, this is a difference of about $2,000) The rotax fuel consumption is worth a bit, at 2000 hours, youve probably put 1 litres more per hour into the 2200 = 2000 litres = $4000 more ! and proportionaly more for the 3300 6 cylinder.$6000. - seems to me your fuel consumption for the Jab is a tad optimistic - More likely up to 5 l/hr difference (could easily be a 10,000L difference or $23K today, for 98 RON). My feeling is the 2200 you end up costing about the same as the rotax, Nice thought and the 3300 end up costing quite alot more - but you have a far more powerful engine that can do 115 hp all day. True but this does not take into account the higher torque delivered by the Rotax at 5-5200rpm which I assume means a more efficient prop delivering the same/more thrust at 75% cruise.. Note: I have focused on the Rotax 912ULS , as I have no experience with the 912UL, comparing it with the little I understand of the Jab 3300

I do not dismiss other opinions - where I have something to contribute, I do. Scathing - for sure! where such a response is warranted. Much depends on the logical progression of the writers case - if it doesn't sound right, it possibly isn't. If there are large gaps/omissions, the writer is either poorly informed or so biased he/she is unwilling to acknowledge information that does not support their assertions, alongside those that do ie not a balanced argument. It is a shame that our debates, so often seem to, degenerate into personal attach.

Faith is a wonderful thing. Those that have it, are often blind to any other reality and so happy in their world. 😈

I note that my questions/observations have neither been answered or challenged. It seem a little unbalanced that I can be taken to task over a spelling mistake but when I ask some searching questions/observations regarding statements made, I am somehow "having a go at a few people lately"😈

Thanks for the spelling lesson. I have made my apology.

I have no idea what you are referring to - please elaborate. How is this" having a go"????

I have no idea what you are referring to - please elaborate.

Think?????????

Speculation: Compared with the 912ULS The main benefit s of the 912iS would seem be lower fuel consumption, reduced chance of inlet icing and FADEC like engine controls. Its claimed 100 hp is the same however I have read reports that it is able to deliver the power such that TO/Climb Out is improved. The big downside is much higher upfront cost. It has been suggested and sounds logical, that the iS can only be justified (cost effect) by high time flight operations ie training/renting as the savings in fuel will only be returned by such operations. For my flying, an iS could not possibly be justified, however I would simply go for a trusty 912ULS, as I have now.

Sorry about the spelling fopa. What has your question "ever owned an aeroplane" got to do with the cost of owning one? So how come you didn't address any of my observations?

Hi Justine, Me again - sorry! I may have missed it in your lyrical support of Jab engines - did you fail to mention/cost that Rotax Recommend 100hr oil / filter change intervals. From imperfect, aging memory, this means that Jabs will have 4 oil/filter changes to one Rotax. Cost$$$ In the same airframe, a Rotax of similar performance to a Jab (ie 80/80 or 100/120) will deliver markedly better fuel economy. Cost$$$ Resale of used Rotax 9's (TBO sales from schools etc) looks pretty healthy. Cost $$$ Just checked the approximate price of a Rotax 912UL (the equivalent of your Jab 2200) $30K - this is probably base price, so lets say $35K, a tad cheaper than the $40K you estimated. Rotax 9's are expected to go to TBO (hrs) & well beyond, with little if any major life extending intervention. It can be a bit of a shock when the occasional one fails to deliver on this expectation but really all mechanical devices are subject to failure, it's just a matter of when and how much it may cost, in dollars, loss of amenity & crew health. (none of the later costed by you) Dont know if Jab 4's have been around long enough to compare but the fact that you have costed sundry life extending intervention, would suggest that they still have some way to go from a reliability (crew health) perspective, loss of amenity (when aircraft in the shop for length repairs). Speculation; Your costed list below for the 80 hp Jab ".......from $..." could easily blow out to a replacement engine every 1000 hrs😈 "Current jabiru pricing is 2200 Engine Gen 4 ** Top End Overhaul from $5,200 ** Full Overhaul from $6,300 ** Bulk Strip from $6,300 **Does not include replacement of substantial items ie. crank, cam , conrods, cylinders and heads. Engines must still be running.. so in actual fact the Gen4 is cheaper to overhaul every 1000 hours by about $15,000. "

Is it an option to have an instrument maker repair it?