skippydiesel

6 minutes ago, facthunter said:

I've been a life time motorcyclist but IF they were Invented now they'd never be allowed on the road. Nev

After about 10 years of accident free motorcycling, I gave up road bikes, in the late 1970's. I spent a couple of months commuting in/out of the Sydney CBD - I had at least one close shave /day. The chicken entrails don't lie - it was time to sell the Honda 750/4.  - just like this one except I had "Walker 2/1 pipes and dropped handlebars. Good open road bike, bit of a pig on sweeping bends.

"well my wife is hoping i will have a plane crash," 😈

WOW!!!! Not good at all.

Nev -"Braised muffler ? "

I think you mean braised oil tank fittings or did I miss something?

Wow! very well presented. Rotax might just have real competition - $$$$$ drop in the wind?

How unusual - corruption within the Public Service 😈

What was the name of the head honcho, who was recently "retired" - playing both sides of politics for his own benefit. Sow him on the goggle box the other day - not one bit repentant.

Way to few public servants (including local council) are held to account for their misdeeds.

Nice looking aircraft.

I would have expected a glider to be able to make at least a survivable "out landing" - inflight breakup/fire???

Wikipedia says the stall speed is 39 Knots -  seems high for a glider, even my Sonex with little stubby wings stalls at 37 Knots (full flap)

My reason for mentioning stall speed - in general, the lower the stall the better the chance of survival.

30 minutes ago, RFguy said:

WRT sonex - it's unsurprising  that a  the 120 hp jab goes faster  the 100 hp 912ULS rotax .

why ? because  at any altitude, it has more power.  simple......

and power = rpm x torque so forget about talkign about torque. 

I dont 't know why that is in any contention. 

 

ideally, thrust would be presented. that's the final say...

 

If it does go faster (just) I would not be surprised however, when considering the Jab it's not just 20+ hp to  it's advantage,  it's also the inefficiencies of the Jab prop speed and additional weight to its disadvantage.

Then we come to mission objective - if it touring, the Jab will use considerably more fuel/ leg than the Rotax , this may impact on the overall speed if the Jab powered aircraft lands for fuel, while the Rotax motors on.😈

As for torque - I would speculate that an engine that delivers more torque, than another can utilise a courser pitch prop, ther by delivering more thrust at a given prop rpm, - what say you?

2 hours ago, Blueadventures said:

Don’t see that; looks historical with Aerovee first, then Jab being similar and air cooled also, then the Rotax as some want to fit those and lastly the newer UL range that will fit the Jab mount. The aircraft first designed for air cooled engines and the Jab 3300 is undoubtably the best performer being 25% better climb rate as one example.

In your dreams - the claims are from the marketing department.

12 hours ago, Blueadventures said:

All the data shows is that the Jab is the engine for performance and a Rotax 912 will never catch the Jab 3300. That's all the manufactures statement is saying.  As such the nice Jab 3300 is the better engine for performance.  Therefore Robins record could be bettered with a Jab 3300 in his aircraft or similar tweaked similar airframe. .

My reading of the Sonex chart:

The engines for their aircraft are in their prefered order. ie the data is skewed in that direction

13 hours ago, BrendAn said:

Who built it. 

Sorry BrendAn - I would need the original builders permission to reveal his name on a public Forum.

1 minute ago, BrendAn said:

A friend of mine has been flying a 912 powered sonex he built for a few years now . I think that is the second Rotax one he has built.

My Sonex started its life in Gippsland - seems to be a hotbed of Sonex/Rotax.

50 minutes ago, Blueadventures said:

Performance of Rotax 912 in Sonex is inferior to Jab 3300 engine after comparison testing by the manufacturer.  Therefore Jabiru 3300 is King in both climb rate and cruise.

Very nice Blue,

I would point out that:

Sonex have only very recently "recognised" Rotax 9 engines for installation in their aircraft, so I wonder how good their data is?

To the best of my knowledge Sonex do not have or ever had, a Rotax powered airframe, with which to arrive at the above figures.

Sonex are so slow to adopt Rotax, that they are only now coming up with a suitable engine mount for future kits

My Sonex Legacy/Rotax 912ULS will easily achieve (Max load):

• 1500 fpm in Climb Out,  80-100 knots, - I am still working on best climb speed.
• 130 + Knot True (150 mph) at 3000 ft, 5200 rpm, @ 15L/hr
• 147 knots indicated 150 + knots (173 mph) at 5450 rpm, 5500 ft, still working on the fuel but believe its 18-19L/hr

If you are wondering about the accuracy of the above air speeds,- the pitot/gauge system has been independently tested and a range of errors noted:

Indicated/Corrected Air Speeds in Knots

40/48.5, 60/66, 100/103, 120/123

140/142, 150/152, 165/166

PS -

• For me, speed itself, is only an indicator of airframe efficiency, when powered by the same/competing engines. Sonex recognise engines to 130 hp however it must be obvious to all, that while the speed may be greater, with such an engine, so is the fuel consumed to arrive at that speed. I want to travel in my Sonex , so fuel consumed per hour for a given speed will determine my power setting for near best range - I think my Rotax will do this for me.
• Do you think the tendency of US small aircraft manufacturers, to express their aircraft performance, in mph might be because it always looks better than in Knots???😈

RFguy, 

"The discussion is aircraft invariant"  

This phrase intrigued me - what is the meaning of ".....invariant"??

Looked it up - means  not changing. So your statement could be read as  - The discussion is aircraft not changing.  Tad cryptic don't you think?

Being short of what few brain cells I was born with, I still do not understand. Please explain?

11 minutes ago, facthunter said:

RPM is not enough . You need a torque figure or a thrust figure as well.   You could be way out. MP might suffice.  Nev

From poor memory (will need to check on next flight) MAP around 22" 

4 hours ago, RFguy said:

skippy , your comment of : " My current Rotax aircraft seems to be delivering about 15 L/hr, 5200 rpm at 130 knots indicated - how would a Jab compare?"

 

Is not valid for this discussion.

 

We're talking about a specific fuel consumption for a specific shaft horsepower (in cruise for total fuel consumption argument ~ 75% ) .

The discussion is aircraft invariant  . 

And no correspondence will be entered into

 

So - for one comment, within many, you refuse to engage - Me thinks that puts all your commentary in doubt😈

I think you will find that Rotax 5-5300 rpm is about 75%  power.

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

2 hours ago, justinjsinclair said:

I completely agree and that’s the whole point. If you are looking at building or buying  an aeroplane or thinking about learning to fly by all means use the web as it it’s a great tool. Agreed But please seek out qualified advice by a LAME, CFI or someone who has real world experience in or on the thing you are looking at.

if someone tells you that something is a bad choice then that’s fine but you really should be asking for facts. The reality is we all tend towards bias, even "LAME, CFI". I absolutely agree with "asking for facts" however, in my limited association with the small aircraft world, it seems to me that bias, in the form of familiarity  unreasoned product loyalty, etc is on a par, if not trumping fact and this observation includes "LAME, CFI".  Confirmation bias is alive & well, reinforced by the retreat into the tribal gatherings, for reassurance/ afformaton. Difference of opinion is met by derision and even aggression.

Dont  trust me either 👍 Good advice but I do own a Gen 4 powered Jab. Happy for anybody to fly it as well.

 

 

14 hours ago, facthunter said:

Skip is it JUST POSSIBLE your last post applies to you?. You are very scathing/dismissive of many other opinions, Nev

14 hours ago, Blueadventures said:

Exact same thought, absolutely agree. 

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.

10 hours ago, justinjsinclair said:

Hey KG, what an awesome post. 
In fact the Jab is nearly 50% cheaper 2200 vs low hp 912 if you add up all the costs in a mature way. SD doesn’t want to put the effort into obtaining the facts but that’s his or her choice.  
Don’t get me wrong, the Rotax is a wonderful bit of kit but now that we are up to $350 hr for a RAA aeroplane dual because the 100’/annual can be $5-7000.00 at LAME rates, I kind of feel a fleet of J160’s is still a great choice for a flying school, particularly if you have a L2 that can maintain the Jabs exactly as per the Jabiru Work pack.

Given that Jabiru is so much cheaper inguess in that case we can probably accept a bit of bracket creep as Jabiru costs increase 😢. 
SD banging on about the top is also a odd thing given that nearly all air cooled engines need work at some stage once they go under that 75 hours per year, having said that the Gen 4 has nikasil bores and the head issues are gone I am betting that the Top overhaul requirement will move as well.

as I said I don’t have a vested interest in Jab other than owning one and maintaining a couple, if anyone wants to pm or call me for further info fee free.

Justin “who identifies as him” 😅

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

9 hours ago, kgwilson said:

SD you are obviously a Rotax evangelist  Bit overstated. I certainly like my Rotax 9. Had great service from the last and hope to have the same from my new one. and that is your right but when I commented in another thread that I liked the simplicity of the Jabiru engine compared to the complexity of the Rotax 9 series you disputed this. I agree (as always) the Jab is a "simpler" engine but "complex" ?? As a person pretty much raised on small capacity high revving automotive engines, I can't say I agree - probably a perspective/semantic thing.  Complexity for me equates with difficulty in understanding /servicing /maintaining, non of which seem to apply. mentioned that the failure rate of Rotax engines is actually higher News to me. Do you have figures and analysis to back this statement? than for Jabiru engines in Australia in 2023 plus a catastrophic failure in a Sling locally. One off incidents do not indicate a trend. All mechanical devices will fail, the question is how long will a type stay in service ie maintain reliability over time. I have no doubt that Jabs have an will probably continue to improve - then the question is  what is the most cost effective engine (within a hp range)  I thought that would be like a red rag to a bull but no not a peep. I don't care that there are Rotax engines with 2. 3, 4 ,000 hours on them. You should, because length in service, without significant life extending intervention, will impact on the cost per hour to run the engine.Plenty of jab engines make the 2000 hour TBO as well. I note, with a wry smile, that you immediately have the Jab at a lower TBO None of these I would guess are owned by private pilots unless they were purchased from a flying school.

 

The Jab engines restrictions imposed by CASA back in 2014 was pushed by some disgruntled FTF owners who ended up as CASA employees and the numbers originally quoted were way over the top but it led to some pretty nasty comments on this and other sites back in 2014. Nowhere else in the world had any issue with Jab engines at the time.  This seems to be a very unlikly assertion. Tall poppy syndrome alive and well again. Jabiru is easily the most successful aircraft and engine manufacturer Australia has produced. We should be promoting local industry and innovation not deni grating it. What would you suggest? - hide our heads in the sand? in the name of brand and national loyalty? Well there are over 2,000 Jabirus flying around the world, "More than 50,000 engines of the Rotax 912 / 914 series were sold since 1989, resulting in more than 45 million" flight hours" of the fleet half of them in Australia and they are exported to over 30 countries with over 7,000 engines having been produced and installed in all sorts of aircraft and even drones. Yes they are an Australian success story and I so acknowledge however initial purchase cost is a big factor in this, as is the low flight hours/year of many recreational pilots. The low hours means that a 1000 hr overhaul may not happen in the time of the original purchaser (ie of little/no consequence) and may also mean that many are predominantly used in local flying ie concerns about reliability, as part of the purchase decision, are reduced. So if you want to argue that Jab meet a need, I would agree.

 

It costs me about $45.00 to do an oil and filter change every 25 hours, about twice a year. The cost per oil change (Jab/Rotax) is likely to be in the same ballpark - the Jab just has to incur the cost X 4 often. How may private owners fly 100 hours a year?  I agree - see below. Most will still need an oil change annually anyway. How many purchased by private owners are going to make TBO given the low annual hours. Most will be out of time well before they reach TBO. As I said above - if you want to argue that the majority of Jabs will only fly a few hours a year, thats fine and whatever additional costs there may be, then pales into insignificance.

 

Your cost comparisons are irrelevant. All the plumbing has to be replaced at 5 years. The jab engine only has the oil cooler hoses. True! (assuming the water cooled heads conversion has not been done😎) In my case I fly 19/experimental, which means I can minimise my costs by purchasing automotive hoses that equal or better Rotax  specifications . I still have to purchase Rotax carburettor rubbers, so about  x2 the cost of a Jab carb rubber replacement.

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"😈

1 hour ago, Methusala said:

Faux pas (not fopa) gaffe, blunder, indiscretion,impropriety etc. I.E. a mistake which really demands an apology, Similar to addressing me as Donna!!

Thanks for the spelling lesson.

I have made my apology.

6 hours ago, BrendAn said:

You have been having a go at a few people lately. Never noticed it before.  

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

How is this" having a go"????

1 hour ago, justinjsinclair said:

That’s ok,  Skippy or what ever your real name is. Tad aggressive 😎
Just like the spelling there is a valid reason for my questions/s
If you can’t get a name spelt correctly and want to sprout anti Jabiru and pro Rotax sentiment that’s fine and it’s your right, just as it’s my right to point out that your (just like mine)  opinions need to be treated with caution. Agreed

i asked you on what basis and education you have to post on the subject. Could not find this question 
Have you built, maintained, flown either of these types. Simple question really ? Never built from scratch. Have done a complete in/out refurb on a composite/fabric and finished off  (intensive 24 months) an all metal homebuilt. I am the sole maintainer.

So many look to these forums to guide them on potential purchases of all RAA style aircraft and that we should all be careful sprouting rubbish that is ill informed and frankly lazy. Is this a generalised comment or are you aiming at me?

We need to be more positive, if someone wants to buy a Drifter, Metroliner or Primary glider we should encourage them and if we are going to poo poo their  idea then we need to make sure we are not hiding behind some pseudonym, drinking almond soy lattes from our tesla on our way to another Microsoft flight sim session where we think a FW190 is easy to fly. (BTW not accusing you of fitting that mould] I agree with having a posative attitude to life in general however when it comes to the purchase of a machine, I advocate for critical analysis (what you seem to infer as negativity) - so many are purchased on the basis of familiarity/brand loyalty/marketing claims and little else.
I know the costs of both Rotax and Jabiru (actually you can add Lycoming, Continental, P&W, Garrett, CFM and RR to that as well) and think both of them are fine engine’s and both have a place in our world. Cost? If we are being absolutely logical, this is made up of Pre Purchase (investigation), Acquisition, Running, Repairs, Insurance, Residue (sale of old) and if being really strict Depreciation (aged brain probably missed one or two). Without a shred of evidence I suggest that Rotax (compared with other similar Hp) will come out as least cost overall.

You are asking me to put in effort to answer questions that you don’t appear to want to put in the effort yourself to answer. If you want me to answer them I am happy to but you will need to pay, happy to invoice you incl GST. Actually not asking you to do anything other than acknowledge that you may have missed a few points in the Jab V Rotax never ending debate
I have no vested interest in Jabiru other than they are a fine company that brings dollars into our country that we all need to pay for our Eectric vehicles, city slickers coffee and pensions. I confess, on a regular basis, to having a love affair with my Rotax 912ULS.🥰

Jabiru Australia tare wonderfully passionate people, they are awesome to deal with and absolutely 100% reliable from a professional point of view. They own their product and employ many Australians. Passion is but a necessary ingredient in the development of any product and its great to hear of a provider receiving such a glowing akolade.
Why we as Aussie’s feel the need to tear them down is quite beyond me. I am so sick of the “Jabiru in the paddock joke” perhaps you might like to see where much of the European technology comes from, might be a nice history lesson for you.

Maaate! Jab make a fine airframe, no question. Personally I would like a little more "feel" in the controls and a lower stall but otherwise hard to fault. I don't need to tell you they have had their engine problems - I hope the Gen 4 will resolve all of them BUT your list of 1000 hr interventions, does not exactly inspire the confidence I would hope for.

have a great week -Justin Thanks and to you too🙂