Jaba-who

I remember seeing video of the crash; what was the correct story?

My apologies I was referring to the paragraph  in the worked text - the statement that single engine aircraft are not allowed to this day to fly over built up areas. And that we are required to follow creeks and shorelines. Somehow I managed to delete a sentence that specified the subject. 

 

Its completely untrue and probably as a result we are going to have nosey busybodies ringing CASA every time an aircraft flies over a built up area.  

 

 

 

The fatal chopper crash that changed Australian aviation history

 

WWW.ABC.NET.AU

 

The accident was witnessed by many and widely reported, creating intense pressure for something to be done to improve safety in the skies.

 

"After the crash, aviation safety authorities changed the laws so that single-engine aircraft and helicopters were no longer allowed to fly over built-up areas, but had to follow waterways and coastlines.

 

That rule still applies today."

 

Interesting Statement - 

About as accurate as most media stories about aviation. Completely wrong. 

 

 

Jaba you are correct of course with reference to CTA.The conditions are listed in ANO 95.55

The ONLY limit currently is pilot qualifications/medical.

 

e.g. I have been using  class C&D for 10 years in a RAA registered aircraft

But lose your medical and you are locked out.

 

The craziness being - move 1/2 a mile to whatever side you need to be outside CTA and you’d be perfectly legal again. 

 

 

Of course this subject has been brought to a head because CASA has actively stated they will consider RAAus endorsements for CTA. 

 

This clearly extends the dual medicals dichotomy even further because they have said nothing about increasing the RAAus medical requirements  to be able to use that CTA endorsement. Nor anything about decreasing GA pilots requirements for medicals. 

 

 

And when that happens with the intent of operating in CTA, very importantly THEY ARE NOT THE SAME AIRCRAFT and along with the different pilot qualifications and the different area, the whole package goes together to currently require a more stringent medical.

Yes, they have the same airframe and yes they have the same engine, but it's where you are going that makes the difference, and if that con gets any traction it will soon be sorted out.

They either ARE the same aircraft or they ARE NOT the same aircraft.

 

You can’t have it both ways. 

 

They ARE the same aircraft and that’s the basis of the argument that two different standards of medical should not apply based on the numbers or letters painted on the aircraft. 

 

If CASA has detirmined that one type of medical is suitable for what ever type of air space is involved CTA or Class G then that one standard should apply. The type if aircraft is irrelevant. 

 

This medical question is not just about CTA it’s about flying in any airspace where dual standards currently apply - which is NOT CTA. There are two different standards for RAAUs and GA flying that same aircraft in Class G.  

 

 

snip ......

I guess everyone realises that the Jabiru registered VH and allowed into CTA is NOT the same aircraft that is registered in RAA, and it wouldn't surprise me if the Senators found out that what Ben Morgan was implying was not correct. It makes me wonder if he knows.

 

snip.

Ummm - you are  incorrect in that. And Ben Morgan is correct. In the context of what he was trying to imply he was also making a correct generalisation. 

 

The EXACT same aircraft ( Jabirus) can be registered in either RAA or VH with absolutely no change to the aircraft. 

 

 And as long as it has the transponder and radio it can be flown by a ppl/RAAus pilot into CTA. 

 

The only Jabiru that can’t is the four seat J430.

 

But aside from jabirus, every aircraft that can be registered in RAAus can be registered in VH albeit in experimental class.

 

If equipped with certain engine types it may not be able to fly over populated areas as such but can be VH and if equipped with transponder & radio can enter CTA. 

 

 

Jaba

There are no droplets of fuel if that was the case the carby is not doing its job. Also it’s not possible one side of 

 

the engine to run lean and other run rich.

 

With all your knowledge you should be able to build the perfect jab engine.

 

i modified my engine to run optimal but you keep saying this probably won’t work or maybe that won’t work.

 ooooh  kaaay!  ?

 

 

MARKDUN

thanks for your comments I had a different air cleaner on mine with that pressure flap and it made little 

 

diferance. I am trying to convince everyone to install a air fuel ratio gauge.

 

 

An AF gauge means little if the fuel distribution isnt even

your only looking at the average and could easily have one of more cylinders running very lean

I have to concur with Jetjr here.

 

(Of course I am assuming you are referring to the typical AF ratio sensor system where it selectively samples gas from one site only.

 

As  has been stated here and on many sites and threads on this forum - the major problem with Jabiru engines is that there is not uniform mixing in the after carby plenum chamber.

 

This then means that depending on the amount of mixing that has occurred gas that is aspirated by the individual cylinders can vary dramatically.

 

This is actually similar on many engines, its just that the massive heatsinks of Lycs and continentals can cope happily with some cylinders running lean. 

 

Jabs are a fine light engine and the cause of many problems is they can't tolerate the same as the heavy old ones.

 

There are a bunch of reasons why they run uneven:

 

Typically the richest (laden with the heaviest droplets of fuel) air has the highest inertia and is carried forward to the front cylinders.

 

The air on the sides of the column of flow through the throat of the carby tends to be the leanest and this air is the least dense and has least inertia and is preferentially directed toward the rear cylinder intakes.

 

There's a further complicating factor - The direction of air rotation in the carby intake SCAT hose. Typically it rotates in a clockwise direction and as it passes through the carby picks up the fuel (in an uneven concentration) as as it passes out the carby tends to throw the densest fuel laden air to the right.

 

Then there's a further complication:

 

In the intake plenum chamber there's an airfoil shaped post in front of the carby outlet. The role of that is to try to stop the swirl of air - but it also can produce complex coanda effects (gas flow sticking to the surface and then leaving at a more pronounced angle in the original direction) which may over-enhance the negative effect in some situations.

 

Without getting into what can be done to ameliorate these -  The point is that all these things serve to either improve or mess up the mixing depending on lots of factors.

 

Often they impede mixing.

 

The lack of mixing is what finally ends up with significant variation of ratios at each cylinder.

 

So a Fuel Air ratio gauge is not going to tell you which cylinders are rich and which are lean unless you have one at each and every inlet because as JetJR said an average tells you nothing about the individuals cylinders.

 

 

I don’t know the advantages of the intake Change good I would think. I had no experience with the 

3300 only 2200. I changed the air cleaner used a auto filter I had the early corse fin heads at times I thought 

 

the heads where to cool. I have since sold the plane I believe it’s still trouble free flying.

Jabiru maintain that changing the intake structure and location makes a positive difference in most set ups. ( both 3300 as well as 2200. )

 

The standard air filter is just an auto one. At one time I had over rich in some cylinders ( can’t remember whether it was all or some or which) and had black soot exhaust. In discussions with stiffy we tried changing to effectively no filter. Essentially to lower the fuel:air ratio. What we used Was actually a very open large hole foam (filter foam made to withstand oil and petrol) coated in filter oil.  It made a difference but didn’t cure it completely.

 

Repitched the prop to a finer prop and that made the most difference. 

 

 

How do you know it did,not make any difference what where you trying to achieve did you say you have not flown 

it yet. How do you know if it is running lean or rich.

Sorry I didn’t make it clear. 

 

I did the initial blockage with card and cut a hole the same circular size as the duct. But it was in same site as the naca duct. 

 

Then flew it for about ten hours with all data collated ( 6 x egt, chts) charting temps against  altitudes and rpms and OATs. All compared to similar data done for previous 10 hours. 

 

Talked to Jamie at Jabiru about it. 

 

He told me they did pressure transducer tests all along the cowel and the reason they moved it so far back was there was still some Higher pressure forward due to ram air on the cowel surface. They moved it back till they found the spot where the pressure drops off. Perhaps mine would get better if it was moved. 

 

So since I’ve been doing other stuff that meant glass work and painting, I’d give it another go. Since it’s not a huge amount of extra work I’ve done the move. 

 

But in the new position I have yet to fly it it. So as yet can’t say if there’ll be any benefit. 

 

something that I’ve found though is that so many times one person will swear that some mod made a difference but others ( including myself) will do it and it makes no difference.  Equally I have done mods that made a difference and I have done significant testing to prove it but when we did the same in another jab it made no difference. 

 

There are just so many differences in people’s set ups. 

 

 

The first thing you have to do is change the intake from nakaduct to side intake. Jabiru has finely done this,

A naturaly asperated engine can’t have pressure into the intake. The best thing is fuel injections people say 

 

it won’t be reliable how many cars stop because of the computer injection.

 

 

Changed from NACA to side duct and achieved nothing

I’ve done the initial experiment of blocking up naca duct inlet with a slab of cardboard and just cutting a circular hole. After discussions with Jamie 

 

And as jetjr found made not a single bit of difference. 

 

Since then I have done some other work on the cowl so I have filled and moved the hole to a flush one in the new position. 

 

The aircraft is yet to fly since doing it so will report then. 

 

 

We’ve been working on and rebuilding jab engines here since about 2007 and done heaps of trials with both cobrahead  modifications and plenum chamber modifications. 

 

When I had my original engine and had issues with over rich on the right and lean on the left I spent quite a lot of time with Don Richter at jabiru modifying them and trialling them. We even tried sieve like grids in the intake ducts but they were a lot of work for no gain in mine (J430 with a 3300) but made a big difference in a Corby Starlet with a 2200 in a very unusual intake path. 

 

But overall the plenum chamber ( which has had several redesigns over the years is still the limiting factor.

 

There is a central  shaft of air with high density  of fuel droplets that carries it forward preferentially to the front cylinders and delivers leaner air to the rear cylinders.

 

Short of some major changes nothing much will change that. Stiffy was always reluctant to change to a more complex system for a lot of reasons. 

 

 

J W

This long range doctor, I believe is not the surgeon just a referral specialist. The surgeons will be "who-ever is on" at the time.

 

My GP has given me a list of telephone numbers to ring and to choose the earliest, I can get to get onto the wait list.

 

spacesailor

I’m confused by that statement. 

 

Sounds like you’re saying ( but I could be wrong) Your GP will send you to someone who will then send you to someone else. 

 

Your GP can refer you ( legally) to the final guy direct. I’m not sure what the middle guy does. 

 

The statement “who ever is on” is an unusual setup in private medicine. It’s the standard in public (free) medicine. The whole principle being you chose your own surgeon rather than be forced to accept any surgeon who may or may not be any good. 

 

Odd set up. 

 

 

Hi Rob,

             I have a good friend who has a J430 aircraft. From day one it was plagued with radio ignition noise. We tried all the usual fixes with little or no results. I did some experiments at home and the source of the problem became apparent. The problem is the negative side of the electrical system, that's why anything done to the positive side of the electrical system yielded no results. Essentially what happens is, the ignition units and the firewall act like transmitters and a  semi tuned aerial system. So all Jab aircraft have a built in transmitter and aerial  in the negative earth system. This happens because there is a thin sheet metal firewall attached to a non metal fuselage. In a metal airplane the charges leak into the rest of the airplane. In a non metal airplane, the charges radiate off the sharp edges of the firewall. Any radio worth it's salt could hear it.

 

 There are some individual differences because of holes cut through the firewall for cables and controls. The particular size of the firewall tunes it to the ignition boxes.

 

 Other non metal aircraft with  jab engines may experience the same radio noise.

 

 Fixing the problem, turned out to be fairly easy.  The firewall was taken out of the earth system (electrically) and becomes electrically inert.  All braided cables and controls have to be insulated off the firewall not just the battery cables. The end point comes, when a multimeter across the engine and firewall shows an open circuit.  This modification dubbed the "Rochedale modification"  was carried out on the J430. No more radio noise.!

 

 All the ferrite clamps were thrown out.

 

 Regards

 

 CL flyer

Did you need to do anything tricky to ensure insulation between the engine, the engine mount frame and the firewall?  

 

On mine the frame bolts to the firewall so that’s a connection. 

 

Just wondering (can’t remember it’s been so long since I installed the engine) whether the big rubbers between the engine and frame were open circuit as they are.  or does it need some further insulation for where the bolts go through the frame. 

 

 

The problem with jab engines they run lean. Monitor the air fuel ratio and be able to adjust and you wont

Have any problems. Lycoming and Continental need mixture ajusment.

That’s unfortunately not  the case Hyundai. Jabs don’t run lean. 

 

Jabs run run all over the place. In the unmodified carb intake they tend to run right cylinders rich while the left  cylinders run leaner  with the forward cylinders richer than the rear cylinders. 

 

This changes with throttle settings. These are most pronounced on most ( but not all) in wide open throttle. 

 

If you put a crossed vane in the cobra head you usually get rid of the right to left imbalance but still have forward aft imbalance. 

 

If  you change the plenum chamber centre vane from an airfoil to a cylinder you may alter the front back and the side to side ratios but in a variable manner. 

 

If you tilt the carby you get alteration in the air stream around the plenum vane and may change the flows in variable directions. 

 

If you measure the fuel air ratios by means of one of the several monitors that measure oxygen and or air and fuel in a single location ( usually  the exhaust) you get no information about individual cylinder ratios. You get a bunch of  figures that makes you think you are onto something but that don’t tell you anything about individual cylinder ratios. 

 

Unless you are suggesting measuring each air fuel ratio at each and every intake port then you you actually don’t get any useful info in Jabirus. 

 

 

Six months just to see a BONE SPECIALIST for their referral letter, then I might get onto a waiting list for public hospital for the next few years.

Have my GP writing the referral to said bone doctor. I heard there is a dr in Merrilands or Wentworthville who bulk-bills, but doesn't advertise that fact.

 

spacesailor

Mmm. I know nothing of said doctor and may be casting him in a wrong light but .... but as a specialist anaesthetist who anaesthetises for a range of surgeons in the private world- there’s a reason some surgeons charge way less, or have short waiting lists. - charge nothing because that’s the only way GPs will refer to them and patients will see them. You get what you pay for I’m afraid. 

 

The other thing is waiting times -  I have heard people say they had to wait x weeks to see Dr. A  but they can get in to see Dr. B tomorrow. Well there’s a reason for that too. Dr A is a fine surgeon who all the GPs want their patients to see while Dr B is a nitwit who stays just one jump ahead of the malpractice suits and no caring GP will let their patients go near. 

 

 

I found the Man Challenge works in changing your mind set on food and works for a small input of exercise with no machinery/equipment. i have only gained weight back due to laziness (not spending 1/2 hr walking and 10 mins exercising each day) which I i now have to work harder at.

You're not alone.

 

Broadly speaking (according to the previously mentioned follow up studies) about 85% of people who lose weight put it back on within about 5 years. ( now I can't recall if it was 5 years but that figure sticks in my head).

 

The psychology of "weight regain" is a whole world of its own.

 

 

Try ANY diet ( and even the weight loss surgeries) you like - free or otherwise.

 

Published Follow up studies ( and there’s a lot of them) for pretty much every diet, good scientific nutritionally sound, fad and wacko. They all basically show that generally the same result happens. Everyone on them, who follows them, loses weight.

 

Broadly they all rely on you eating less and moving more in some way or other. The complex theories and notions on which they are based are often wrong but that’s irrelevant. They all make you become more aware of how much you eat and cut it down.

 

The problem is the long term keeping it off.

 

It’s the maintaining the lifestyle and dietary change in the long term that is the kicker.

 

 

Bit crap that a diet from CSIRO which is owned by us charges for a diet that helps reduce health costs to the nation.Typical neo capitalist crud.

Nope. My understanding ( could be wrong since I didn’t go into it fully).

 

It’s free -if you lose weight.

 

You pays the money. Go on the diet and lose weight and get the money back. You only lose the money if you don’t lose the weight.

 

That’s part of the psychological incentive to work through the diet properly.

 

 

Oops my mistake. An oil change with a new filter is 3 quarts, not 2 as I originally said.

In that case, you have same engine as me:thumb up:

 

 

I’ve been using the Jabiru top of dipstick condenser for a while now. It works. It no longer dumps oil. Recommend.

I will cut and paste your post but change by just a few words and it’s just as valid.

I’ve been using a mark on the Jabiru dipstick where it stabilized at for a while now. It works. It no longer dumps oil. Recommend.

 

 

Jabiru have had a venting problem all along and with a small quantity you don't want to lose much. Slight overfilling seems to cause a quick loss to a more or less stable level. The vent system is of too small a cross section, plus a lot of Jabiru's would have a high blowby situation. If I was doing long trips often I would have an inflight top up capability. Nev

I’ve never heard of a jab needing in flight top ups. Of the five or so at our airport I think you’d not find a single one who fits that description (except for dumping excess rapidly and then becoming stable). Certainly I’ve had two 3300s which both dump down to about 2.9 litres ( in a few minutes of flying )and then stop. Mine go for 25 hours without needing more than maybe 50 or 75 mls top up.

That seems to be the norm. This concept of jabs losing oil is pretty much an artefact of people expecting that there should the book value of 3.4 l in it. Every time they do it dumps it and people then top it up again and feel it loses oil.

 

I tried an oil recycling system ( built my own - a baffled tube with convoluted path for condensing the oil out. ) but in the end I took it off. Can’t recall exactly why. But I don’t lose any anyway so it was an experiment in superfluous redundancy anyway.

 

 

If you have to ask ...... you can’t afford it.

 

I’ve owned two aircraft and neither costs were anywhere near what my projected costs were.

 

The helicopter was just light years more and the fixed wing much closer but still more than I expected.

 

 

Thanks for this, I am very familiar with sched 8. I have just read through all the appropriate bits in the RAA tech manual. It's a complicated business, but seems to have freedoms that don't exist elsewhere.For others reading, my scenario above may work in the RAA world with a two seater, but not anything larger. I assume this may change in the future if the weight restrictions change.

 

Thanks again.

There’s been no suggestions anywhere about RAAus increasing the passenger numbers.

 

 

With regard the VH experimental maintenance.

 

If you built it ( and satisfied the authorized person AP - is the person who does the special C of A - that you built the majority of it ) AND have done a maintenance procedures course (MPC) then you can maintain the parts you built.

 

There seems to be a variation in interpretation of the rules when it comes to how much you can work on an engine that you “simply installed out of the box”.

 

If you didn’t build a section you can’t work on it. What constitutes “building” has a bit of latitude in interpretation depending on who you talk to.

 

Then more recently was added:

 

You can maintain an aircraft you own, if you did not built it but it is substantially the same as an aircraft you have built and for which you did or do have authority ( and all the above things like MPC etc ).