question Rotax 914 Jabiru J230

[skippydiesel]

I would guess that this might represent a marriage made in hell for the die had Jab/Rotax crowd but I would be interested to have some informed hopefully factual comments on this aircraft merits/shortcomings.

 

So - how does the aircraft perform, particularly in comparison with a Jabiru 120 Hp powered J230 ???

[Kyle Communications]

The Rotax 912UL 100hp Jab that used to be at caboolture used to get along really well...just very noseheavy apparently...I believe though its sold now and gone down south somewhere

[skippydiesel]

Hi Kyle - this is a 914 but I would rather not talk specific aircraft (getting a bit personal) - more intestine in general observations of/possible experience with the same.

 

Oh! my reserch suggests that the 914 is lighter than the 3300 so wonder why the 912 powered version would be "nose heavy"

[facthunter]

I don't think anyone's put a 914 in a jab 230 yet The 912 is a weight problem requiring weight to be added to the tail and the 914 will be moreso Weight in these places will adversely affect spin sensitivity. I've flown the 230 with standard Jab 6 engine and it's a good power weight performance match and is exceptionally smooth.. Nev

[Kyle Communications]

Maybe the Jab at Ycab wasnt a 230 but it did have a 912ULS in it. Everyone who flew said it was way too noseheavy...I never flew it but a lot did.

[jetjr]

Yes there is a 914 J230/430 getting around somewhere

[Old Koreelah]

Maybe the Jab at Ycab wasnt a 230 but it did have a 912ULS in it. Everyone who flew said it was way too noseheavy...I never flew it but a lot did.

A Warnervale-based Jab (a J-160 from memory) which I did some training in was re-engined with a Rotax.

I believe it ended up in Qld, so it may be the one.

[skippydiesel]

The one I am interested in lives in Qld and is definitely powered by a Rotax 914

[Kyle Communications]

Where in Qld?...I am not aware of one certainly around here

[phantomphixer]

I’m guessing that a 914 powered Jab 230 / 430 might be ok for a VH-Experimental rego, albeit a bit nose heavy.

That could only be done with a kit built RaAus rego due to LSA rules applying to factory built craft but I don’t know what MTOW would be granted, possibly sacrificing pax, baggage or fuel allowance.

I don’t see any reason why you would go to the expense of messing around with the balanced, lightweight and proven combination that Jabiru offers. It’s as reliable as the next type when maintained correctly and smooth with power to spare.

[skippydiesel]

My reserch suggests that the Rotax 914 is lighter than the Jab 3300 - so wonder why the 912 powered version would be "nose heavy" as a couple of respondents have suggested??

[Old Koreelah]

My reserch suggests that the Rotax 914 is lighter than the Jab 3300 - so wonder why the 912 powered version would be "nose heavy" as a couple of respondents have suggested??

If it's the one mentioned in my Post #7, it was designed for a 2.2, a much lighter engine.

[pylon500]

For a start, you don't need to go to the expense of a 914 when cross fitting.

I flew an original J230 down to have the Rotax mod done to it, a 912s was installed, it was test flown (by me), and then ferried back to it's owner.

With the 912s, the performance was basically the same, it could cruise at 115kts if pushed, although I tend to be a little more casual and (as shown in attached) would sit on 105kts @ 4930rpm.

Some like to push 912's harder, and they'll take it, but in the 5000 rpm range they only drink around 16Lph.

This aircraft would also climb at 1200fpm @ 70kts with no risk of overheating.

I can't remember if the battery was moved down the back for CofG reasons, but remember, 230's are nose-heavy two up, but nice solo.

If you're used to the sound of the old Jab six, the Rotax 'buzz' can take a bit to get used to, but you're not listening to every valve movement waiting for something to happen.

[ATTACH=full]53405[/ATTACH]

[ATTACH=full]53407[/ATTACH]

Well that's annoying, wrote this a couple of days ago, but forgot to hit the post button!

DOH!

[pylon500]

Anyone else see my attachments? I just get the oops message...

As for J3300 vs R912s weights, the totally installed and running weight of the 912s is probably just a little higher than the 3300 after you add two radiators, coolant and an oil tank.

Obviously a 914 would be heavier again.

I know there's been a few '100' series Jabs with 912's fitted, and balance was a problem, but the length of a J230 hardly notices it.

Going to repost the attachments just in case... (I think last time I must have hit Preview instead of Post)

[Shortfielder]

914 has a good reputation and makes more power at altitude so should result in good cruise and climb performance, especially with mppc. Jab is a solid airframe, so the combo sounds good. If the aircraft in question is the one advertised in Qld, there are two flying clubs nearby, so you may be able to have an independent test flight done before making offers, travelling etc.

[facthunter]

The 230 is fine even when loaded on a very hot day with the six. Not necessarily so the 430. as a more than 2 seater. A turbo'd motor should be better at higher levels and with a C/S prop but the $$$'s and weight in the wrong places. I think the 914 is a bit on the complex side for operating outside of Europe where you are closer to service centres. Nev

[planesmaker]

I have a 914 j400, and love it. Balance wise it is really good, actually better than a std j400 that a friend built at the same time as me. He was recommended to limit wt on back seat unless wt was added up front. Performance is really good, I do have c/s prop. Rarely use full power for take off, 100hp at around 650kg we climb at 800ft/min. 115hp , 1500 ft/min. Empty wt 345kg. A j230 is a little heavier with the longer wings. I have not needed ballast wt added. I think I know the aircraft you are talking about in qld although I have not seen it I believe it is not the tidiest aircraft around. A 914 is about the same wt installed as the Jab 6, including radiators etc. A 914 is not difficult to operate service wise. I’m A very happy Jab owner. :)) if you are ever close to Tumut come for a fly!

Tom

[skippydiesel]

I have a 914 j400, and love it. Balance wise it is really good, actually better than a std j400 that a friend built at the same time as me. He was recommended to limit wt on back seat unless wt was added up front. Performance is really good, I do have c/s prop. Rarely use full power for take off, 100hp at around 650kg we climb at 800ft/min. 115hp , 1500 ft/min. Empty wt 345kg. A j230 is a little heavier with the longer wings. I have not needed ballast wt added. I think I know the aircraft you are talking about in qld although I have not seen it I believe it is not the tidiest aircraft around. A 914 is about the same wt installed as the Jab 6, including radiators etc. A 914 is not difficult to operate service wise. I’m A very happy Jab owner. :)) if you are ever close to Tumut come for a fly!

Tom

 

Thanks Planesmaker - that's what I call a real well informed response.

Other than empty weight increase, what impact does the longer wing have? (J400 v J230)

As your friend has the Jab powered version of your aircraft, hopefully you might be willing to make some comparative observations.

[jetjr]

Smaller wing is faster, some say easier to fly, but has slightly faster stall, ie 2-3 kts

Whole lot easier to hanger being some meters narrower

Weights are the same and I think the short wing underwent much more spin testing

Long wing was done to meet new stall for LSA

[skippydiesel]

Smaller wing is faster, some say easier to fly, but has slightly faster stall, ie 2-3 kts

Whole lot easier to hanger being some meters narrower

Weights are the same and I think the short wing underwent much more spin testing

Long wing was done to meet new stall for LSA

 

Hi Jetr - J400 smaller yes by 1.45 span and area, about .12 m2 but of course this is not the whole story. Long wings with a narrower/ faster aspect (hope this is the correct term) ratio seem to be the norm in European designs eg ATEC Faeta Span 9.6 m , Rotax 912 uls, economy cruise 135 knots - stall 28 knots. So span is not in itself a determinate of speed. However if this is your actual experience - thank you for the information.

[facthunter]

Bigger wings give better performance when density altitude applies, as well as lowering stall speed.. Of course once you are in the air and not too high, you don't need the wing so much as it will slow you down.. Always a trade off. The wing section that gives you more speed may be inclined to drop it's bundle suddenly at the stall. AND require very accurate manufacturing and have no oilcanning and usually not be fabric covered. etc. Thin section wings are harden to make strong..Nev

Edited May 24, 2020 by facthunter

[planesmaker]

J400 stalls a little faster than the long wing, longer wing about 30kg heavier, anybody correct me if I’m wrong but a std J230 is around 380kg. Short wing is definitely easier to hangar. :). Performance difference between std j400 and mine is quite marked but I have a c/s prop. Mine climbs much better even at 100 hp takeoff. Cruise about the same. I cruise 115kts @ 17lt/hr 4800rpm

[Paul davenport]

I have seen planesmaker take off at Mt Beauty with a full load of people and baggage very impressive , well done Tom. Good to hear real world actual experience rather than why it can’t be done

[planesmaker]

Thanks Paul

[facthunter]

I don't really think anyone has said it can't be done.. Nev