Kenlsa

Bruce, the Gen 4 that has been on 98 since new has now had its 100 service. Camera inspection shows no/zero/zilch residue on piston or chamber. L2 took a photo and the rest of the fleet is now on 98 by now afaik. Note——-the new fuel filter had plenty of muck inside and some was metal (magnetic test) we are loading from drums at the moment until a bowser goes in. Ken

RF, Yellow/whiteis result of avgas residue. All our club Jabs are on 98 now due to avgas residue forcing us to lap valve every 150 to 300 hours Wire brush it all off with a brass rotary brush on a drill- piston tops (you may scrape them with a small steel ruler to reach inside if the cylinder is still attached to the case) and combustion chamber- and the lower stems of the valves.( This will be very hard and may need machining -see below) if you see small grey spots on the valve and/or face -that is lead. use a factory go/no go gauge on the valve stem guides. It may be too tight. If so BEFORE deciding on new guides, ream out the hardened carbon with the factory reamer (I forget the size), you will be surprised what come out! then recheck the go no go gauge again. You almost never need new guides. take the valves to get recut at an engineering shop.$10 per valve. Then lap in the valve to the seat (again, you probably don’t need to cut the seat as well, just a lap will be ok) Oil and reassemble , with same collets to valves DONOT mix them up. then torque to 24lbs. fly for 5 hours and then re torque.... ring me if you want Ken

I’ve done a few......engine crane strap onto the prop flange the jack it up till the nose wheel just touches the ground. This will put a force onto the rubber mounts giving you plenty of room Ken

Unless your 230 is 19 reg, you will have to get permission from Jabiru to alter anything from the LSA specification build Ken

My Colt has a 6lt capacity but has a running minimum of 2lts. at a cruise rpm of 2300, mass of 110kg, sump of 6/2lts, compression in the 6’s, no cooler (or filter) Lycoming has got the parameters right for this aircraft, speed and longevity. But it takes many $ and time to get it right. Change just one thing, be that speed/cruise/ climb, weight, prop etc, it all starts again. I think Jab has it right for a 2200 @100kts in a slippery airframe and a 3300 @120kts. All this with only a relatively few engines built compared to others. Ken

Annum, having flown most types of jabs I have a bit of a “rule of thumb “ UL. Not flown one SK -need more rudder and elevator SP - fast, sporty, land straight away, not bad in turbulence 160- good speed, land when you want them to even if you are a little fast, roomy, good in turbulence 170 -roomy, need to watch landing speed or you will float, getting tubbier every year 200 top plane though 85 kts best glide can be an issue if having to land in a small paddock 230 good a/c with good speed, though working on 6 pots can drive you crazy if you need to remove the centre heads and barrels and having to use a crane lift to get enough space to removed the carb fuel bowl hope this helps, others may have observations of their own Ken

A mate spoke to Jabiru at length when they didn’t have a cooler as ours was overheating (he was a person who did this for a living, think rocket propulsion and turbines) and tried to work out the size of internal finning required. Long story short, fins inside absorb heat from the oil and this heat then travels to the coolest part of the structure (sump) which on the outside has a rough surface so any high temp travels to the tips of the casting and tries to equalise with the cooler atmosphere. Same deal when making a heat sink from ally sheet; when you cut it with shears, don’t file or polish it as the very small rough edges bleed off the heat much quicker than a polished surface. the maths didn’t work out and the factory had already worked thru that internal fin question and found a cooler was a better option. All been done before! Ken

Reading this topic confirms that I am the long lost fourth brother of the 3 stooges. Ken

T88, the fire was quite exciting with 170, FK and Grob 102 along with the hangar damaged or destroyed. All our fleet are trickle charged when not in use. All the holes lined up that afternoon; the smart charger turned out to be not so smart, the battery cooked leading to a small fire and the fuel tap was left on so the heat destroyed the fuel line and the fire was fed by the gravity fed tanks. All over in a few minutes. So solenoids fitted and taps off at the end of the flight. only problem now is I get zapped on my watch band if I’m not careful when checking the air filter! Ken

Skippy, any battery that I can put in the Colt (sorry RF not a Jab) must be approved with an STC to make it legal.

I am out of my depth here with all this tech info. I yearn for the days when we looked out the windows for traffic and we used to fly low and buzz our mates to let’s them know we had arrived. Ken

Looking at weights for a rebuild, the EarthX (LifePO4) at 1.7kg beats my Colt lead battery at 12kg. It comes with an STC but is spendy at $600 US. Still, I may have to install it if weight becomes a last minute fight. The STC for a Hawker (Odyssey) will come in at 7kg. I am updating the alternator and starter anyway so it has become an option Ken

While I don’t have a problem with the AD it is over a year old. we all are aware of glaciers that move quicker than CASA. Ken

I note that 760 is up for another consultation in the new year according to CASA. So I spoke to RAAus 2 weeks ago about it and it was also confirmed to me that at 760 kg, a LAME will be the only one that can work on my Colt. CASA will not budge on that requirement even after Part 149 comes through. The Tech team suggested that I could go the LSA route with a max empty build of 413kg to fly at 600 kg, and I can conduct the maintenance myself. I have started the rebuild and will/should be able to comply with the 413 rule. I will still get a LAME to sign off on my rebuild just in case I can’t make the weight and so will have to stay on the VH register. So far have put have put it back to the basic option by making it day VFR by removing all of the lights. All the extra instruments (vacuum) and right tank will come out this week. I have researched light weight alternator, starter, batteries (choice of. odyssey or earth x as both have STCs) and will get them in the new year. I have contacted Oratex and will apply for the STC for the Colt. Projected weight is 405kg..........so far..... Ken

Looks like I'm getting old, the 2000rpm should have read 1500, sorry for the confusion. Found the original computation and this was further tested (still cant find the file though) in still air at 65kts that gave the best glide. You should be able to work it out and test for your own prop/plane combo. Happy computing ken Best Glide RPM - Copy.docx

The nose leg is designed to collapse as it is the built in safety feature to minimise a tip over. All correct! Ken

Old K. mine has a 2.2. I will see if I can find the workings he used for my plane and prop numbers. Ken

The true glide performance at mtow in my SP 500 is 65kts. By true I mean the prop is not providing any thrust or breaking force. At 1200rpm (settles at this rpm at 65-70 kts in the landing circuit) the prop is providing a breaking force and will not give you your actual performance so you can feel the true picture. My ARDU mate did the calculations for zero thrust on my 60x44 prop at various speeds to ascertain best glide. I gave the formulas somewhere but suffice to say after all the testing was done in still air, the maths gave us 2000 rpm for zero thrust and 65kts was best glide. Note that rpm varies at chosen speed for zero thrust. Last couple of times I have done my BFR, I have throttled to 2k for my “engine failure” so as to simulate actual performance. Ken

Our club is going strong and we are looking to increase our fleet to 5 and one extra on line. Here in SA we were treated as adults and never stopped flying during COVID. Regarding aircraft sales; nobody can travel freely to view any potential purchase and others may be in financial strife and unable to be an owner right now. I read that confidence is increasing generally so fingers crossed I will be putting an aircraft up for sale as soon as all the boarders are open so as to appeal to a wider market. Ken

Good to see the article in the OZ on the front page of the “Future Adelaide” insert. Ken

Can anyone that owns a J120 inform me of their actual weight. As I understand it with the heavy U/C and ‘lectric flaps, the build weight could be around 305kg. I know that they have put on weight since the first ones with the thin legged U/C and manual flaps, and smaller panel. I don’t believe any factory numbers so no need to quote them. My SP 500 that is one of the very last; with the J120, 3rd iteration fin and rudder, comes in at only 276.5kg. Coz if 305kg is now the typical weight, I can weaponise mine with a 3300 and still weigh less than that. Ken

Car rego In SA lost its label about 5 years ago, much to the Police Commissioner’s annoyance. It was reported a few weeks ago that the number of out of rego. vehicles had doubled within12 months and continues to this day. This would show that of the 1500 per year that were prosecuted B4 were mostly the criminal type but now we are pinching the extra 1500 for forgetfulness....even though we get emails etc. Some still forget. There is no onus on the State to issue a reminder notice. the cost saving was reported at.........$1.00! Though this seems a bit low. Ken

At Gawler we had 2 complainers a few years ago. We already practice noise reduction by way of circuit direction and training times. I bumped into one of the complainants at a Xmas show and it turned out that he worked for the same department as me......his complaint was the blue stroke micro lights at first light (due to thermal activity I reckon). He had done his homework (court prosecutor) and could recognise a micro from a Jab etc. He thought the Jabs were very quiet and quite liked them. He was generally on board as far as flying was concerned. Over a couple of years the micro guys traded “up” to a j200 (he is on this site I think) an SK and a Foxbat etc so that fixed the blue stroke noise. The other complainant was a woman who was insistent that we were loitering over he house taking photos of her in her yard.........you can’t argue with stupid.... Ken

I’m with Bruce on this one. I fly a glass plane and most in our club planes are glass. Seeing all the troubles that beset our students and the very infrequent private owners prangs, I have come to the conclusion that That insurance on a glass plane probably isn’t warranted. (Tho club a/c are, as risk is too great for the committee) They are very easy to fix and very inexpensive. We have had a number of end overs, torn out nose wheels and wings impacting objects and u/ torn off. Multiple of each. All fixed quick smart and cheaply. If it was so bad that it happened to be written off...no problem...coz so are you and you won’t be worried about it. Tube and fabric is also easy to repair. A car jack to pump, piece of string to check straight and a bit of cloth to cover. Carbon can be problematic as you need to cook it. We have had 3 tin planes come to grief in recent times. one touched a wing due to a stationary undercarriage collapse and I mean hardly a touch, $26k and six months to fix. You couldn’t even see the damage. Another didn’t make it to airfield crunching the u/c....a write off. Similar to an episode in our Jab that only took couple of layers of glass, 3 new bolts, one week then back flying. latest tin plane incident involved a hard landing and the pilot didn’t even know he damaged it. Probably used to the Jab that can take anything you throw at it. Cost $25k and 4 months .....so far. So, FRP..do it yourself Tube and fabric. Similar to FRP Carbon...expert and insurance Tin....”don’t leave home without it” Ken

I fly Recreational not GA so I don’t care. The world as I know came to an end when Shell stopped printing road maps. Ken