Markdun

Sounds good. Having radiators in series like you describe means you need twice the pressure differential (entry minus exit pressures) for them to work which would be hard to do, particularly at low airspeeds. A friend’s Tecnam has the oil and head cooling radiators facing the airstream (like my J200) which gives you plain ram air pressure at the entry and engine cowl pressure behind on both radiators. Lots of air leaks, and with two small cheek vents and a small exit, it’s not surprising he has high OT two up in the summer. Its 24 registered so no playing with it.

That’s good. There are some articles on this in either Kitplanes or EAA (RV focused). Seems the critical thing is not having the inlet too big, having a smooth transition as the inlet expands so the airflow stays attached, & having a big expansion chamber. The Jab standard cooling plenums apparently fails on all three. It’s also a factor for the cooling air exit; but there it is a matter of accelerating the now slow warm air up to your airspeed. Theoretically you can gain thrust with an exhaust augmentor, but I think the practical goal is to reduce drag by providing for the exit air to accelerate (as opposed to putting in a large ramp/skirt angled down fwd of the air exit). Some racers put streamlining on their bottom engine mount tubes and ensure all fuel/oil tubing is neatly tucked away so as not to disturb the exit air smooth flow departure. We are talking about a 100-200kias aircraft aren’t we? Another point to keep in mind is that even though ‘the radiator is the only exit for the air’, it will only work IF there is a pressure difference. If the air pressure behind the radiator is close to ram pressure because you have two large cheek inlets filling the engine cowl with air at ram pressure, then it’s doomed to failure. When I did the LCH conversion on the J200 I had to reinstall the jab fibreglass cooling plenums, because without these the pressure behind the radiator was too high (as well it left the cylinders not well cooled). When I find a round tooit that I’ve lost I’m gunna halve the cheek inlets’ aperture and construct lighter cooling plenums from those cheek inlets directed to cooling the barrels. I might also then halve the exit air outlets & chop 15cm off the exhaust so the exhaust can help accelerate & extract cooling air.

Skip, maybe some semantics. Stay away from ‘mat’, like ‘chopped strand’ mat unless you are building an anchor. You want cloth fabric with warp and weft around 200gsm or less. For larger surfaces go the woven rovings but I’d say 600gsm is way too much. Your goal is that fully wetted fibreglass/ carbon/Kevlar with epoxy has less than 50% epoxy resin. If you want more stiffness in the layup do one or all the following: increase compound curve, introduce a layer of foam, even 2mm between two layers of cloth glass (Jab do this on their cowls) & epoxy, or use carbon cloth or lay on some ‘stringers’ (strips of poly rope with a layer of cloth on the bias laid over it). My LCH J200 has a Gen3 Jab3300 in it. ‘Pressure recovery chamber’ is where you have an expansion chamber after the air inlet to reduce the kinetic velocity of the ram air which is converted to pressure as per Bernouli to increase the air pressure differential across the radiator (which is the beginning and end of liquid cooling). The RV racing guys are the full bottle on this for their engine cooling plenums. It allows you to reduce cooling drag to a significant extent if you are going fast. A simple scoop (or a radiator facing plain ram air like mine) is like a dragging a flat plate through the air like a parachute.

Try some vinyl hose ( say 10mn od), cut a longitudinal slit in it and fit over edge, hold it down how you want the radius to be like with fine safety wire or hot glue…. Coat in pva release agent. Another method is to supa-glue light braided polyethylene ‘rope’ to the edge and just wrap the fibreglass around it, leaving the ‘rope’ in the layup. Remember also that in laying woven fibreglass cloth, it will go around small radii if you lay it ‘on the bias’, ie the warp and weft go +45 and -45 degrees to the edge. It’s a real bugger if you have any fibres aligned 90 degrees to the edge. A ‘scoop’ is going to be draggy & inefficient. Why not have a pressure recovery chamber? Is space an issue? Not that I’m fussed about this as my LCH J200 has the radiator full frontal between the prop and oil cooler inlet. Mark

Glen, I’ve put aside a large diameter 1 litre plastic bottle for you, although I’ve heard others had had success with ziplock polyethylene bags (including inside their sleeping bag to avoid going out of a tent mountaineering). I’ve always found avoiding inflight service or failing that landing at an alternate has worked for me.

The hydraulic valve lifters bottoming out (out of adjustment) and holding a valve slightly open is a not uncommon problem with the 3300 with the older longer pushrods (Gen3) and which have suffered some head recession. What I was advised by Jabiru to do was to check at each oil change whether the rockers could be moved by hand fwd and bkwd (sliding) along the rocker shaft a fraction of a mm at TDC power stroke. No need to rotate valves. If the rocker can’t slide along the rocker shaft a smidgen (it will also swipe the top of the valve stem), then you need to investigate further. Also when assembling the engine extract the oil from the lifters so they are all bleed down and measure the tappet clearance when assembled. There’s only 3mm working movement of the lifters so to be in the middle of the range you should have about half of that (it’s not exactly half because the rocker aren’t 1:1). I’ve found in most engines you can swap around the pushrods as they are not of identical lengths to get a pretty consistent set up. In a couple of engines I’ve found a couple of pushrods significantly different in length…obviously mix ups with early and later versions. I think someone (Jabiru) should produce a colour card for the rocker boxes colour, like spark plug manufacturers. I’ve come across some totally black ones: real doosies. I too, expect shiny ‘silver’ aluminium and have my CHT panic alarm set a bit higher at 155C. Cheers, Mark

Sorry Skip. I think my main point is that if you’ve got wing tanks the fuel level sensor issue is not easy…. hence go for calculated fuel remaining with a good fuel flow sensor & EFIS and beer prepared for the effort to get it setup/calibrated. The low level warning in my book is a distraction. All builders know about the free fluid effect and the need for baffles…. Still shallow flat tanks are much harder to ‘gauge’ even with baffles than say a cube.

Yeh yeh…you can never have too much back up. How many of us fly with a parachute? I haven’t removed the 3.5 l header tank low fuel warning light (might save a 100 grams) in the J200, but I wouldn’t have made the effort to install it. Really a 20 minutes warning because you didnt plan the fuel reserve properly? The risk is that with that system you don’t plan your fuel because your know you have the 20 minute warning .. its like ignoring the risk of dingo attack on Fraser Is because you know the bad ones have been killed. As it goes if I’m flying at 2500agl I’ve got 3 minutes at 700fpm sink rate to do an outlandiing…. So to the chagrin of my snobbish GA mates whose Lycosaurs never fail, I fly with an outlanding paddock already picked out & I might actually diverge from the straight line course to ensure it is within gliding distance. Perhaps it’s that NZ gliding hours experience with instructors pulling the tow release at 150’agl, or deploying the spoilers to drop one below the ridge between you and the airfield and calmly saying, ‘it’s your aircraft’.

I’m not a great fan of the low level warning light, because if the light comes on, it’s just confirmation and proof you’ve already fucked up; a bit like the mirror found on many magnetic compasses—-its there so you can see the fool that’s lost. The problem is that wing tanks being shallow produce a lot of surge and waves and a small vertical distance means a lot of fuel…as opposed to say a cube. That said, I’ve had experience with a Tecnam that has wing tank resistive float sensors which were very good, although I didn’t rely on them using fuel flow ‘calculated’ and the bit of paper & Flight time times estimated fuel burn from the POH every 20 minutes to cross check when we flew it across from Kal to Forrest. We also checked the fuel in the tanks with a graduated stick before taking off as well. I am pretty much sold on the calculated fuel from fuel flow using the EFIS with cross check to a window to see the fuel sloshing around. Once the fuel flow transducer is calibrated AND you have sorted the Jabiru voltage regulator pulses problems, they are very accurate and the computer happily calculates nifty things like ‘fuel remaining at next waypoint’ and fuel burned per nautical mile (enabling you to adjust throttle for best efficiency. Skippy, the problem with seeing the fuel level in the hose is an issue. Most fuel hose has reinforcing and that makes it even more difficult…but it does work. And if you play around with the size of the holes you can get some damping if it’s subject to surges.

I have constructed or modified several fuel tanks: all have fuel level gauges. First one was in a Minimax low wing aircraft with a 20 litre tank (fibreglass) above one’s knees. Fuel level sensor was a stainless wire (from an old Teleflex cable) with a cork glued onto the lower end. The wire passed through a copper tube brazed on the fuel cap. The amount of wire seen in front of the windshield indicated the fuel level. It failed once when the cork fell off…fixed with some safety wire. Very accurate; very reliable. Slight drag (but whose to say in a 65kt Aircraft). Second was a 67 litre tank in my Cygnet SF2A. This tank was composite construction: plywood with epoxy coating and joints filleted and reinforced with fibreglass. The tank is mounted behind your head. It has two fuel level sensors. The primary one is a clear fibreglass ‘window’ facing forward with calibrated markings going vertically up. Absolutely the best. The second is a translucent fuel hose (& vapour return line) which is good but not as good as the ‘window’ sensor. Over 1000 hours & 23 years there’s been no failures or problems with the ‘window’. Like I said it’s the best. The translucent hose one requires frequent replacement of hoses and it’s difficult to see the fuel level sometimes. It also has a good fuel flow and calibrated fuel remaining which you can cross check with your visual and manual calculations as I do (I’m a nervous flyer). Third is in a Corby Starlet with a 40 litre aluminium tank which is also ‘above the knees’ like the Minimax. In this aircraft I installed a high tech resistive float sensor designed for a motor scooter. I calibrated it (tail down and tail up) and programmed the EFIS accordingly, including fligging around with dampening to reduce wild fluctuations from fuel waves in the tank. It works, but I ignore it & rely on an old Navman fuel flow transducer connected to the EFIS which gives ‘calculated’ fuel level. I’m thinking the knitting needle with a cork would be better. Fourth, is a J200 I recently restored. It came with the wing root ‘window’ gauge, the wing root mechanical gauge (little round unreadable display) and resistive outputs to the EFIS. None of these work reliably, despite careful calibration and dampening. One minute I’ve got 70 litres remaining, the next it’s 15 litres. A piece of paper noting the estimated fuel burn and flight time is a thousand times better. In addition I have calculated fuel level from the fuel flow sensor (expensive ‘Aircraft’ one); but this too is total crap as the fuel flow reads 60lph until the bus voltage reaches 13.9V and then reads as it should…so I trust it as much as I do a politician’s promise. In the 100 hours in this aircraft I rely on the window sensor, although whenever you climb the fuel sloshes to the rear and you see no fuel in the window…. and I’m thinking a fuel leak and where’s that big paddock? In summary, first preference is the window in the fuel tank so you can actually see what’s sloshing around. Second preference is the knitting needle with a cork. Third is a piece of paper recording estimated fuel burn and flight time. And by the way, the plywood fuel tank in the Cygnet has NEVER EVER produced any water in the fuel…. Unlike the aluminium tank in the Corby. Just saying. Cheers, Mark

Was it a meteorite? Brings to my mind when I was sailing from the Percy Is to Great Keppel a few years back and at 3am I saw what I thought was a red parachute flare. I was about to radio in a relay mayday except the red flare appeared to accelerate over me along with a sonic boom and roaring noise heading south east where it disappeared. Definitely was not an hallucination as it was a typical dead flat inside the reef QLD sail, so no need for the coloured dreams scopolamine patches.

Consider installing a smoke system which you turn on in the circuit…that might make you more naked eye visible to others. Glen, the other thing with a passenger is to enlist their assistance in eyes out of the aircraft, because as we know, most ppl are doing pre-landing checks on downwind (distracted) & mainly concentrate on outside visual observation for other aircraft just before turning onto a circuit leg. Yeh I know that even that, as is all ‘see & avoid’, will be crap because the human eye/brain is just not effective in picking up ‘non-moving objects’ in the sky; ‘see & avoid’ fails at the ‘see’ because you just don’t see intercepting traffic. Raymarine and Lowrance also produce low power(digital) 360 degree 10nm radars which ought to pick up other boats/aircraft ~$3k. The radome is a cylinder about 50cm dia & 15cm high. They are normally bolted onto a yacht mast spreaders, but I’m sure you could fashion a streamlined fairing to mount above the fuselage in front of the vertical stabiliser.

Yes, VW conversions were notorious for icing, particularly at the lower ‘T’ join where the two sides came together at the rear bottom of the crankcase, as seen in the pic above. A simpler solution is to weld a thick steel tang (not stainless) to that T which bolts to one of the crankcase bolts. This conducts heat from the crankcase to the T. Oh, and also have a carb heat system. I flew behind a VW conversion like this for over 700 hours mostly in the southern tablelands of NSW and never once had to pull carb heat despite flying in icing conditions. Mark

This was my track from YGLB. First leg wiggly…. Dodging clouds.

Why didn’t you go into class E, as you do have the SE2?

Many years ago I was asked to pay import duty on a box of parts (mostly AN bolts) from Aircraft Spruce clearly labeled ‘Aircraft parts’. I was initially told that because they were ‘bolts’, duty applied. After a bit of a whinge from me, ‘ the parcel is marked ‘Aircraft parts’ and that’s what they are so the duty is zero’ etc, including asking how I could formally have the decision reviewed, the duty ‘charge’ magically disappeared. I think the big part of the problem was that the courier was DHL and it was their ‘try on’ rather than customs as it was then. But to the present I thought that import duty has for the most part been abolished (except luxury cars etc) and in its place you pay GST, plus the shonky non-tax tax of Home Affairs (Customs) charging you a handling fee plus a fee for paying the GST (or something like that). So if you paid AUD$5,000 for that box including shipping, that would mean $500 GST plus the handling fee and fee for paying the GST, so $750 would be about right.???

Thanks Glen. When I’m next asked for any medical conditions I suffer from I’ll add ‘inept’ along with ‘intolerance’. -:)

That doesn’t seem correct. When ADSB was first being introduced the RpT industry (Q &V) were prepared to pay Airservices for all aircraft to have ADSB out fitted for ‘free’ to the aircraft owner on the basis it would save them more money in fuel savings particularly at regional airports, ie based on then using ADSB ‘in’ to avoid recreational and charter aircraft etc. The recreational side of aviation like GFA and RA-Aus were apoplectic with rage that this would herald in Big Brother and every RA-Aus flight would end with 3 AFP vehicles a CASA inspector and the arrest of the RA-Aus pilot on terrorism charges to be tried in a secret Star chamber court. The GFA has concerns that no glider could thenforce ever climb a thermal because of the mass of the battery to power the ADSB device. Oh, how times have changed. But I’m happy to concede that perhaps RPTs didnt fit ADSB in because without the surety that all aircraft have it, what’s the point? I fitted the SE2 after having the shit scared out of me by a heavy military helicopter travelling in the opposite direction to me at my altitude while I was downwind 1000’agl in class G airspace. We missed by about 250m. They weren’t on the area Frequency. My subsequent follow up communication with them indicated they rely solely on ‘see & avoid’, ie roulette, but ‘usually have the ADSB turned on’. And the SE2 has been fantastic for avoiding them since.

I shouldn’t be so obtuse. The SE2 is well known for failing LEDs. I’ve had one replaced on warranty. This one I know of the GPS LED is blank, that’s equivalent to green. Any thoughts on an inductive passive GPS antenna for it, say built into a mount?

I think my SE2 has the GPS accuracy indication correct. When it’s first turned on its one green and two reds on the LEDs and once it’s going ‘properly’ its 2 greens and a blank for the GPS led.

The trouble with those numbers on torque is that what you are seeing is variation from other variables, which are unrelated to bolt tension which torque is merely a proxy for. I doubt the head cap screws are the same alloy as the cylinders and the variation are probably more to do with varying electrolysis / corrosion of the threads of the cap screws in the cylinder. Most likely the lower head screw has less corrosion and moves easiest. FWIW I think the purpose of head bolt tension checks is to assess whether there is recession, except perhaps a check at 5-10 hours after the head has been replaced. As such I think it is better to do head bolt tension checks far less frequently than specified in the maintenance manual, and to do the torquing properly, ie dynamic by backing off and then re-torquing. And given how easy it is to pop off the head on the Jab to have a squiz, why not do that at 300 hours?

A couple of years back I asked ATC when I was 25nm east of Canberra at 4500asl. They had nothing from the SE2, but I was visible with the Mode C xpndr. We also checked whether Musk’s satellites could pick up the SE2 (my brother as the global lead ADSB engineer as he was then, had direct feed from the satellite system) and it didn’t, even with us fiddling with orientation to maximise emissions towards the satellites. That’s the consequence of the low 25w power of the SE2. I really don’t understand what ‘calibration’ an installer does, or is this another bureaucratic totally meaningless word like ‘committed to’ & ‘take seriously’?

Just saying, all the comments about this new form of anarchists might not apply to this defendant as it was only the prosecution’s assertion. We have the debacle in Sydney that the police invented a ‘fact’ that an ambulance was blocked crossing the Sydney Hbr Bridge by a protester and this resulted in her being remanded despite it having no foundation. Is that possible in QLD? Also laws theoretically apply to all ppl, citizen or not. I say ‘theoretically’ because whether someone is prosecuted often depends on their gender, skin colour, social standing etc etc etc. So I’m not so big on responsibility to the state. however, my whinge is big corporations paying zero or very little tax still demanding the protection of our laws and courts to enforce commercial contracts & protect their interests and their owners liability is ‘limited’. That said, I agree with all the comments about the dip shit ‘sovereign citizens’ & the RWNJ ‘freedumbers’.

Best to look up the actual law, and it looks like QLD is quite a bit different to NSW. Below is QLD. So arguably, if you are flying unlawfully (without a BFR, no log book, with an expired ERSA, or in an unregistered aircraft, unlicensed) you could be done for manslaughter, and depending what ‘unlawful purpose’ means legally, murder. That’s not an easy question to answer. In 1775 a Miss Johnson contracted with a carriage maker (Holmans) to construct an elaborate carriage for her to tour the streets of London to drum up business for her very successful brothel. She took delivery of the carriage and refused to pay Holman (perhaps the gold leaf wasn’t thick enough or velvet soft enough?). Anyway the court rejected Holman’s case saying they would not give support to an unlawful and immoral contract. This precedent was watered down substantially by Australia’s High Court over whether a NT pastoralist had to pay a water bore driller’s invoice for bores drilled illegally which didn’t find any water. They said the pastoralist had to pay. But that’s civil, not criminal. However, in NSW some druggies invaded a Sydney house for robbery (unlawful purpose), were caught by the occupants who tied the two of them up, called the police, and while the police were on their way, gave them a bit of a whacking with a cane. Result was that the occupants were convicted of GBH, despite a statutory provision which purported to give them immunity (the reason was that once the robbers were tied up, they were no longer engaged in an unlawful purpose, they were prisoners). I think there is a lesson there re sequencing of actions. Anyway, a long winded way of saying flying unlicensed may not be an ‘unlawful purpose’ in itself as opposed to, for example, if you were stealing the plane. CRIMINAL CODE 1899 - SECT 302 murder 302 MURDER (aa) if death is caused by an act done, or omission made, with reckless indifference to human life; (b) if death is caused by means of an act done in the prosecution of an unlawful purpose, which act is of such a nature as to be likely to endanger human life; manslaughter 303 MANSLAUGHTER