Vev

I also went along to Oshkosh and sat in on almost all of the electric workshops and discussions .. also met and spoke with all of the manufactures about their products. The Yuneec guys were much more advanced in terms of a commercial release and their products look quite good. They had a 40kw motor mounted on a wall stand and I got to have a go at playing with it through the power and speed range .. the most interesting thing was how quiet and smooth it is. Without exception all of the manufactures are waiting for the next step in battery technology .. most seem to think that Li -Air will be the next gen to provide the energy density they need. The problem is the cycle capacity is only around 3 or 4 cycles compared to 1500-3000 with Li-Po. I think the technology is already here but they need an engineering solution to sort out the cycle performance. Never the less, the whole programme is real and alive using Li-Po and they are making great strides .. if I was a betting man I would say we will see a real commercial solution in the next 5 years that will meet the reliability and durability we will need for avaiation. Very exciting times to come. Cheers Jack

Dont read too much into the SG as avgas has a technical range between 0.690 and 0.760 ... Oil Co report the typical SG in their specs... the actual SG will vary from time to time and always does. Cheers Jack

Thax Ian ... Very powerful reminder ... I have just shared this with some firends and family. Jack

Modest Pilot, Here's the technical specs and Material Safety Data Sheets off the BP web site for Mogas ULP 95 BP Australia - Technical Data Sheets BP Australia - Material Safety Data Sheets Just select Road Fuels in the drop down box. Cheers Jack

Jab already have a fuel injected multi port system which is sold to Israel to power UAV’s… the system is not available for manned flight and is not the be all end all answer some may think. Comparing any of the older Jab engines to the current engine is no comparison .. whilst the Carby and induction system needs improvements (which is under redevelopment) the engine has made some great strides in the last 2 years to improve cooling, lubrication and detonation management. Cheers Jack

Spot on Brian ... 90% of these problems are over heating issues. The magic numbers is to keep the EGT below 1250 deg F and CHT in the middle of the green at around 275 F ... need to make sure the carby jets are fat to keep EGT's down and that air flow through the engine cowl are correct .... tooo much pitch on a prop will kill them very quickly too .. as you said good airspeed and plenty of air flow works wonders. Cheers Jack

Hi Deadstick, The earlier piston had convex domes .. you have flat but these are not the latest pistons. Cheers Jack

G'day Deadstick, You may want to check on what is current with Jab as there has been many updates on the new top end that has made a significant improvement on engine durability. They have fitted new pistons with more ring grove clearance and a bigger slot for the oil drain back, new cyclinders, new heads with 50% more fins along with a new shape to the combustion chamber and new over head gear and push rods ... the new pistons dont have the notch on the crown (they have also removed the centre dome on the crown) and only have a tit over the piston pin mount which faces the front (prop)... I guess what I'm trying to say is there are many changes to the current engine that you can retro fit onto your older engine and dont use the old bits to compare what is now available as standard from Jab. In my view the new engine bits has made a good engine great. Cheers Jack

Guys, Hate to say it, but if you have fitted the pistons with the notch to the back (fly wheel) you have put the pistons in wrong way around .. the Jab manual is quite correct. Forget about rotation for the moment and fit the pistons as per the manual... try marking the centre line of the piston on the underside of the piston crown ... you will see the pin is off set to the centre line.... now assume the rod part way down the power stroke 90% ATDC, now draw a line through the big and little ends ... you will note that the line between the two centres will intersect with the centre line you have marked on the underside of the crown. If you put the psitons the other way around it will be way off set which will drive the piston down the bore sideways during the power stroke. Cheers Jack

I have the MRX in my Jab 160 and it works just fine ... you do rely on others having there transponder on but it has picked up many aircraft before I have had a visual. It's another set of eyes to help you find traffic and worth ever cent. Cheers Jack

Hi Chris, I exchanged a few notes with David Birrel who said he would raise the issue with the RAA board ... so far no feed back at this stage but I will follow my end and check progress and let everyone know. Cheers Jack

Hi David, May be I can answer some (not all) of your very good questions re premix and the impact on fuel burn. Firstly the calorific value of fuel is actually increased owing to the higher density of the two stroke lubricant (approx - fuel 0.7 – 2 S oil 0.88) when blended… additionally there is very small increase in viscosity, which does have an effect on the flow characteristics of the fuel through the jets. The energy value will remain somewhat the same either premix or injected and at a ratio of 50:1 the viscosity change is really very very small … the viscosity is more affected by heat variations. Just as a matter of interest … generally speaking, as the ratio of 2S oil increases you see a corresponding increase in fuel energy values and usually peaks at around 16:1, which is very rich .. however there are some poor side effects, these being a drop in Octane performance, plug fouling and coaking etc. Pre-mix has been around long before oil injection and is a reliable method for lubricating a 2 stroke engine … there has been a few exceptions, but mostly premix is considered a very safe method of lubrication. The main thing to be concerned about premix is its use by date … the shelf life is very short and you will see an accelerated drop in lubrication quality and octane when stored. It’s always best to use fresh. Btw … Cetane number or index is a diesel fuel measurement which refers to combustion ignition delay and nothing to do with petrol fuels energy. Hope this helps? Cheers Jack

Well done FG ...

In support of a plain language weather report, I wrote to both Ian Baker and Rod Birrel. Rod responded and has agreed to table my request with the RAA Board and follow the matter through and feedback. Hopefully the RAA may see an option to approach CASA and reduce the complexity for weekend pilots and improve safety as well as get in line with other parts of the world. Regards Jack

I have identified the actual Bosch parts; 3300 engine Cap GB74 Rotor GB73 2200 engine Rotor GH600 Cap GH506 Cheers Jack

Hi Russ, I assure you that Opan is 100 RON Octane and not 91 ... the feedback you have been given is the Marketing Spec and not the Actual Typical Technical Spec. The base fuel is made from Iso-octane the same as Avgas less the lead (0.55 gm/lt for 100LL).... you can't make a low volitile fuel from anything else in such quantities. Cheers Jack

Hi Bone, Under the right conditions (which I won't explain) bitumen could easily kill someone siniffing it.... I really hope this doesn't catch on. I'm not sure if I understand your statement correctly, but I do not believe that Opal is worse for sniffing, which I might add is tracked very well by health authorities and reported quaterly since 2005... the reports show a >75% reduction in related petrol sniffing problems as the components that make you high are at such a low levels it makes it very hard to get a hit from it. However I an interested to hear your view on the causes of auto engine failures due to Opal fuel, but might be best to leave this at the risk of going off topic. Cheers Jack

Hi Russ, What you would have Googled was the Oil Company “Marketing” spec which is a claim in terms of a minimum octane, which is 91 RON to meet the ULP legal requirement… this spec doesn’t limit Octane above a legal min spec. The reality is… Opal fuel can’t be sniffed because it is made from an extremely low aromatic hydrocarbon (low volatility) called Iso-Octane, which is the base product they make Avgas. In fact Opal is Avgas without the lead and has a RON of 100 and is the highest octane fuel form a service station possible. It’s all in the detail and you need to go beyond the "marketing" spec and look at the actual chemistry …. Hope that explains things a little better. Cheers Jack

Hi Russ, Your comment about Opal Fuel being low octane fuel is quite incorrect ... Opal is very high Octane ULP fuel at around 100 RON. Cheers Jack

Hi JM, Thanks for that ... I am fitting a carbon fibre prop and fitted it today with all new nuts and bolts. Cheers Jack

I just found some details in a Jab construction manual for all models. They say to rotate the engine until one set of flywheel magnets are at the top and then fit the prop in the 11 - 5 o'clock position. Cheers Jack

Need some help in terms of propeller fitment? The Jabiru service manual for the 2200 engine does not provide any details in terms of a position for fitting the propeller relative to the crank. I was intending to fit my prop at 1-7 o’clock position with number 1 cyl on TDC. Can anyone provide any help or insight? Regards Jack

Hi JR, You mentioned failures on the 4 cyl Jab ... how many, what type of failures? Have these been reported and investigations undertaken by RAA? Cheers Jack

Hi Dave, Just hang in there mate ... it will all become second nature after a while and you will find it will get hard wired into your DNA. Everyone feels over loaded when you frist learn and everyone is capable of a bumpy landing even with 1000's of hours under their belt. When you balloon the 160 you find you are usually too hot and using too much stick movement too early ... talk it over with your instructor and get him to walk you through the technique. If it all feels like it's going wrong or it's NQR just go-around and have another go ... the runway will still be there when you get back. Cheers Jack

Turbo, Yes the boom is shorter (about 50cm) on the 170 compared to 230/430 and the v'stab is slightly smaller too as is the rudder by a tad, but they share the same wing. I have flow the 430 a number of times (and yes it is different to the 160) but its about being gentle and patient and not being too hot over the fence. I must admit the 120 and 160 is my fav Jabs of all of them to fly in unsettled conditions, but I do love the big wing Jabs on a hot day out of Roxby Down. Jack