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You should have known me back then Nev. I used to very cheaply build my own radio control gear using acorn valves out of walkie-talkies from the government surplus shops. I could have saved you a lot of money. The fluttering rudder (galloping ghost system} left lots of room for improvement though.

All is right with the world then. I got out of models when the RC took off. It was nearly as expensive as the real thing. Nev.

Just for giggles….my Gen1 SP500 uses 11.7lt/hr. 100 true @ 2800rpm with 44” pitch wooden prop. Just sold it this week after 18 years. Why you may ask? So I can pay for the rebuild of my Lycoming: And can now look forward to 24lt @ 90 kts. Hmmmm ! Ken

RC stands for Radio Control. The Aerobatic class has approval to operate in the Danger Zones of the Moorabbin Training area up to 1000 feet.

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

Too big for control lines. Nev

They're about the size of an RC Aerobatic aicraft.

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

was going to ask what are you doing with the old prop?

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.

I am confused by your posts. I thought you said you could not fly your plane and now your converting to taildragger after a few years as a nose wheel. Have you flown it. Just curious because I really like the look of hummelbirds . I think they would be a terrific aircraft.

They are a very pretty aeroplane. Nev

Agreed. While I'm coming on board with the ZD engines viability, I am very happy with my nearly time expired flying school engine. Always the same workshop, at the same airfield. And I already have maybe 20 hours experience with this engine from when it was in the plane I hired. Price difference is huge, and I am confident I have a reliable engine.

if you change to the composite prop (from the wooden prop) you'll find its worth quite a few horses....

God knows why my linked in is there 😬😬 please ignore

RF GUY or Guyette or they them are is now 🙏 If we leave the head oil heat GEN123 aside nearly all of the Jabs that I have seen that are regularly flown have beautiful bottoms ends when the top end comes off. i suspect the secret to Jabs is that they must fly regularly, a friend of mine owns a Baron B58 and they get an extra 400 hours on TBO if they are doing 500-1000 hours a year. Perhaps we should investigate something along those lines. 💁 maybe 50-100 hours a year, I really enjoy doing annuals on regularly flown airframes but those 5 hours a year things are hard work as nothing is kept warm or moving . For a Jab there is not a lot of extra work for the factory to open up the cases at top time so if it was me I would be just getting a full overhaul, I am still hoping the 1000 top requirement goes to the normal piston standards. Paul Cherna has opened a lot of engines lately and I think he is a fan of the bottom end. I am no engineer but the crank and rods look a bit like a race engine spec mmmm gear box, turbo, EFI mmmmm🤪 Ohhh I do love a good fuel efficiency chat 😈 The fuel economy question is one of my main passions, yes it’s very sad but it’s what I did for a living for a few years dealing with mainly jets and turbo props. Just like hull speed in a yacht each airframe has a sweet spot for the load it’s carrying. Fuel, power, weight, load CoG, cleanliness, level selection yadda yadda yadda all make a huge difference. It’s almost impossible to measure fuel economy unless it’s done by history and even then it’s hard to measure. I flew my Jab home from Wagga to Brisbane in one hit, it seemed to TAS at 103 at 7500 and seemed to be 15lph. Since then we just call it 17lph for safety. If it was in loiter/drone mode I suspect it’s back at 11 lph at 70kts. That’s over 10 hours fuel 😫, I would have thought a Virus with Rotax EFI would be even better but that’s a guess. In my limited RAA experience it would appear that very few pilots fly long legs with enough granularity to really get down to useful efficiency figures. https://www.linkedin.com/in/justin-sinclair-29aaa175?utm_source=share&utm_campaign=share_via&utm_content=profile&utm_medium=ios_app

Justin(e) , the Jabiru 2000 hour overhaul... might require a crankshaft , camshaft etc, likely raises the cost significantly. If you are a 19- flyer, then you have your own discretion to assess things like camshaft and crankshaft condition. I understand a 2000 hour full overhaul of the 912 , replacing all the parts that rotax specified must be checked for wear .....is essentially uneconomical . I believe it runs more than 70% of a new engine (in parts) to do all the items. Rotax make it that way intentionally I am sure . They want to sell engines. The Rotax at 2k hours still has plenty of reliable hours left in it , assuming it has a good life with clean oil and little avgas . The Jabiru you really do need to pull it down and do a overhaul. The Lycoming.. well they are known for going more cycles than cats have lives. Again, rebuild cost can vary in experimental categories. As JackC said , flying is not cheap or free to just open your chequebook.

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

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

A crate 582 complete with everything , except a prop cost me $14,500 delivered, people will say it’s a crap investment but flying costs money and I don’t care. Gee I drive an old Landcruiser like 45 years old, needing a fuel tanker chasing me everywhere 🤩 who cares My Jabiru 230 blows up tomorrow? I will just ring up Jabiru for a new Gen 4 out of their stock, chuck it in and happy days 🤩 Fun was never cheap and we only get one life……

Yes, agreed, the 2000 hour rotax still has more than likely plenty of hours left in it. you might get a 2000 hour 912ULS for 3k-8k that will do another 1000 hours without cracking a sweat But if it breaks, be prepared to chuck it in the bin (with a set of four sets of rings = $1400 !!! ) The 2000 hour Jab is ready for another top end overhaul. 6k-8k inc new pistons, lifters etc . and Then you could get another 1k hours from it if it was well looked after and had nice clean oil all its life..

A quick look found a post from Riley on this forum back in 2016 - maybe worth a shot if you get no other leads. “You can try Dieter Sedbauer, in Morayfield, Qld. (0414 504 116). He took over the Sweetapple prop facility when Richard finally retired.”

Well, it's his choice to remove the earth spike, but he has to live with the consequences!

These Hummel-Birds do look a lot better , as mr Hummel designed it. spacesailor Rob, see photo's previous .