Oscar

The trick is, to increase the 'exit' side so that it improves the extraction low pressure. It's not just area, but the effective venturi effect that lowers extraction air pressure. Have a look at the Cessna cowl flaps for a 172: cowl flaps cessna 172 - Google Search The outlet area is hardly much more than the intake area - but it works.

Bruce: we did ours at CAMit, thanks to Ian Bent and the wonderful crew there, on an engine that is very probably the OLDEST engine ever to have any CAMit mods. The only guy who can give you the answer, is Ian Bent - but I would have to say, that my co-owner and I spent nearly three weeks at CAMit in all, to strip, clean, modify and assemble our engine. Ian and his crew not just tolerated us, but helped us on every step of the way - you could not ever meet a greater bunch of blokes. It is seriously humbling to have someone stop a $m-dollar CNC machine to show the process being undertaken to create a complex part out of billet - which they would do out of pride in what they were doing! We are two old retired farts time-rich but not very pecunious, and it was a wonderfully satisfying time for us, as we learned new skills and a huge appreciation of just how complex it is to make a decent aircraft engine!. Think - the ULTIMATE 'men's shed' for aero-nuts... run by people who have the humanity to tolerate and help 'peasants' become basically knowledgeable in areas that they had only ever dabbled in. We'd both built competition car engines, at the amateur level, so we didn't need to be taught how to use spanners.. but Jab.-based engines are another level entirely. If you have the time and the inclination to become a 'three-week apprentice' at CAMit - and if they have the time now to accommodate you - you'd come away with knowledge and satisfaction of achievement that is almost impossible to purchase - and some new friends. Otherwise, my suggestion is that you consider a CAMit 'core-rebuild' engine incorporating all of their mods., or contact Ian Bent for any new information regarding other alternatives.

Neil: for both ASTM-certified aircraft and certificated aircraft, the installation is the aircraft manufacturer's responsibility. The certified /certificated engine achieves that status by specific testing of the engine alone, to meet the required performance specifications. The certified / certificated engine has to meet performance standards as defined - the installation needs to meet the requirements defined under the engine performance testing limits. If - for instance - you install a Lycoming engine in your airframe, Avco Lycoming will ONLY honour its guarantee when it has done an audit of the installation to ensure that it meets the performance for such matters as cooling, fuel flow etc. that were applied for its certification. An airframe manufacturer selling a certified (for all practical purposes, a 24-reg. aircraft) is responsible for the installation - NOT the engine manufacturer. If the airframe manufacturer decides that it has provided an installation that is not in accordance with the engine manufacturer's installation requirements - then it is the airframe manufacturer's responsibility. Your problems - as I understand them - are entirely the fault of Fly Synthesis / someone who modified your aircraft without complying with the manufacturer's requirements..

Aldo - my comment was not meant to be a criticism, and 25-hour oil changes is a very conscientious maintenance schedule. My comment was based on the fact that the standard Jab. oil system doesn't carry much heat away from the heat-critical areas, and also the fact that too much oil-cooler area - unless modified by the use of a TOCA (CAMit makes one) - tends to introduce overly-long warm-up times on the ground that can be very bad for the head cooling. IF you have the CAMit oil-piston-cooling mod. installed ( I have it), then you certainly get a heap more cooling effectiveness from the oil and oil-cooling efficiency is very important. The oil-spray to the piston crown reduces the potential for detonation under heavy load considerably, and also reduces the likelihood of ring impaction from burnt oil.

A Mig-15 went in at Canberra some years ago, killing both occupants and all but taking out around 200 people at a sports field, as the pilot sacrificed his life for the greater good ( RIP, that pilot). Nostalgia for Warbirds is a powerful emotion, but frequently is utterly misplaced in terms of sense. A combat aircraft is designed for a specific mission - and longevity is NEVER one of the specifications. That is why there are thousands of 'retired' warplanes just outside Tucson, Arizona - for starters. Alloys that simply disintegrate over time were used in their airframe; engines with no real TBO were used at ratings that defied analysis, other than 'replace when it breaks'. We will NOT be seeing private F111's in operation. You have a way better chance of flying safely in a 1930's warbird maintained by a savvy LAME than in a 1980's or onwards warbird. Live with it, or go against it and quite possibly die with it.

Um.. Nev: Distance: 2500k... (New Zealand glider pilots break world distance record_English_Xinhua) Endurance: 56 hours 15 minutes (Flight endurance record - Wikipedia, the free encyclopedia)

Nev - absolutely agree. That thing was off the ground so quickly, that I think some headwind was happening (or it was one hauling mother bear of a winch). A decent headwind gets you high in a very short distance on a winch, but the corollary is that if you are going to do a full circuit your turns need to be damn tight, or by the time you are tracking downwind you don't have enough height to do the 'base/final' turn (all one half-circle in that situation.) I'd rather have a few knots in hand for the turns than trying to feather it around at too low a speed while being blown downwind.

Nev, the way it was explained to me was that at less than at least 600 feet, you will normally land more or less straight ahead, so your first action is to get the thing into 'flying' condition, i.e. in normal G, and then decide the next action. My first break experience was on the third ( from memory) launch - and we hadn't actually practised breaks at that time. About 400 feet, just as you start to pull the steep 'kiting' part of the climb ( probably why the wire let go, of course) and I had plenty of strip ahead, so I kept the nose down, pulled brakes, and kept them full until the start of the round-out - though I had plenty of strip ahead, (Forbes) the last thing I actually wanted was excess height or energy!. But, it's not ever completely 'formula' - obviously. You have to make decisions - quickly - depending on the circumstances. If your best option is going to be a full circuit - 360 degrees of turn - then you may need to make it a very tight circuit and pulling any sort of tight turn without sufficient airspeed is going to cause serious problems, - you'd know this heaps better than I do!. Starting the turn too soon and having to kick it straight out of an incipient spin wastes more height and space than waiting just a wee bit longer.. It's actually quite similar to sailing!. When you are tacking in a yacht, if you try to get the main tight after the tack before you have the headsail drawing properly, that will drive you right back into irons and you slow, lose rudder power and go dead in the water. Particularly noticeable on cats and tris...

Where I salute the Pilot's reaction - and obviously his training and self-discipline - is that pause while not just the speed stabilises but the fact that he quite obviously WAITS until he has proper G underneath him. I've had a few - and in a Blanik you feel as if you're going to drive it into the ground waiting for the negative G to go away...

Perfect response. He wasn't at the steepest climb I've seen on a winch; his climb speed appeared to be around 65 kts, so the nose-over to gain flying speed wasn't as dramatic as is fairly normal - ( probably around 3 seconds at least in a Blanik before you get the stick back out of the panel), but note the INSTANT response of the stick all the way forward and no aileron input until the speed is stabilised. ( Note the pause between the 'Speed... And turn' comments.) Spot on, great video.

Communist, no; devout disbeliever in and opponent of power over a society being wielded by those who have a vested interest in any religious institution - absolutely.

OK - I'm not sure that we don't confuse - because I simply don't know enough about the intricacies of the situation - what we generically lump together as 'Islam' or Islamic religion, with different practices and cultural beliefs that are fundamentally tribal rather than founded on the precepts of the various interpretations of the teachings of a particular 'prophet'. And by 'tribal' - I do NOT mean to insinuate that this is peculiar to those who choose to follow the teachings of Mahommed (choose your spelling there!) - we don't have to go very far back at all to look upon the violent schism in Irish society between warring 'tribes', both following (ostensibly) the words of the 'prophet' Jesus Christ. We like to think that Australia is a secular nation and our lives are ruled not by religion but by rationality. Is that really as rock-solid as we would like it to be? I for one will believe that when I, as an individual, have the right to choose to end my life when I decide it has reached its use-by date - and that is a position that is, apparently, shared by a very considerable majority of the population. I cannot think of ANY fundamental right that is more fundamental than my right to that choice - but the views of our 'Christian' religious zealots drives the law. If we truly had the ability to 'reform', the majority will in our notionally democratic population, would enact that reform. One of the 'Ten Commandments' is - I believe - 'Thou Should Not Kill'. But we continue to dispatch soldiers to do just that, to people who pose no immediate threat to us. Our observance of fundamental principles to which we ascribe our higher moral standing than other 'faiths', in the belief that we are being decent, rational, compassionate and moral beings, is in fact modified for base political purposes whenever it suits. If Australia is ever under attack from any forces - be they notionally Islamic, Taoist, Mormon, Confucian, Hindu, Pastafarian, Catholic, Zoroastrian, Protestant, Scientologists, Darleks or Klingons (as a short list), I'll be out there passing and using the ammunition - but not praising god. ANY god. I have to say - that I'm warming to Hanson's idea that we SHOULD have an RC into whether the Islamic faith per se is inimical to the Australian 'way of life' ( which is an entirely confected notion, actually). While the very idea that it would be 'Royal' - which is some sort of nebulous imprimatur to which we as a vast majority do not believe is relevant to our society - it might just have the gravitas in its findings to STFU the idea that 'Islamic faith' is a danger to our societal values. I sincerely believe that there is nothing in fundamental Islamic teachings that presents a danger to our society; let's get it out in the open. There ARE ethnic and cultural values - quite apart from religion - that shape individuals attitudes. In my experience, you'll get a far more explosive reaction from a youth of Middle-Eastern ethnicity by dragging him off at the lights than by your lady friend wearing 'provocative' clothing. I don't believe - but am ready to be corrected by those with better knowledge - that there is anything in the Koran (Quaran - choose your spelling, again) about the religious purity of a WRX vs. an AMG 6.3CSL. But, and this is an extrapolation but I believe has some basis from observation - we have experience of major aircraft crashes resulting from an ethnic disposition against being demonstrated to 'fail' - generically termed 'keeping face'. And that particular characteristic has absolutely no foundation in religious beliefs, it is an ethnic thing. Of course, we 'civilised' people don't do that; we just 'press-on', or make bad judgements from 'get--home-itis', or... pick your explanation. What I would like to see, in regard to immigration, is an approach that says: 'Here is what Australia requires of you to be a welcome member of society. Here are the things we hold dear; if you do not agree to support them, then go elsewhere.'. I would support the deportation of those whose explicit actions do not meet community standards. I would absolutely support the instant deportation of an Imam who states that "scantily-dressed women are plates of meat' - and I would also support the continual incarceration of the 'elders' of the Exclusive Brethren, since we can't (unfortunately) deport them. I would support incarceration of pan-nationalistic zealots of the 'Reclaim Australia' genre, who have an entirely distorted view of how this country evolved with Anglo-Saxon occupation. If we can move beyond religiously generated socio-political positioning to look at all of the people we are now - there are mere fine shavings of differences. Only those on the extreme edges of those differences threaten our society. We have had religious differentiation between communities for practically ever: but the extremely Protestant community of say, Glen Innes and the extremely Catholic community of Toowoomba, don't wage war on one another. Sydney and Melbourne people restrict their intense rivalry to insults and football.. (and go to shop at either where the prices and merchandise are best). I am all for the nullification from from our society of the sociopaths who will attach to their miserable existence any useful tag to justify their whingeing: religion, gender, sexual preference, eating habits, unquestioning advocacy of support for one economic philosophy vs. another. But let's get that into perspective: it's not just those who adhere to the Islamic faith. I personally have more fear of the long-term consequences of failing to address the growth of climate-altering substances than Islamic-faith nutters. If we get to the stage of having inadequate oxygen to sustain our lives, we're going to bloodyt die gasping like stranded fish alongside our supposed worst enemies.

OK - let's not forget, that the practice of castrating young boys to preserve their peculiar vocal range and delivery, was only finally outlawed in Italy in 1870. Female genital mutilation (for ANY reason, religious or not) is strikingly abhorrent, but we fine Westernised cultural groups have much in our not-all-that distant history about which we ought to be ashamed. How moral was it to castrate young boys simply for listening pleasure?

I have a 6.5 Swedish Mauser (for pigs and feral dogs) and a Sportco .22 for rabbits and snakes - legally held and stored.. Haven't put a round through either in the last couple of years. The Red-bellied black that bit my dog in the lounge-room last summer and all but killed him, is lucky I didn't see it. I have the greatest suspicion of people who own guns for the sake of owning guns; they usually also own pitbulls/pig-dogs, jacked-up utes with six spotlights on the roof and 'Feed the girls meat' logos on the bumper... but they probably won't shoot me meaningfully, just as a by-product of irreducible drunken stupidity. And they're mostly called Gazza, Bazza, Trevor, Mick, or Kylie. The gun legislation has - possibly - removed guns from some of the most chronically stupid in the community - a positive. What it hasn't done - and could not do - is remove guns from those who have the utility for their use for criminal purposes and the intelligence (or money) to acquire them via illegal channels. I wouldn't place it as better than 50% success overall.

May I politely point out, that in Australia, you are (statistically proven), EXPONENTIALLY more likely to be killed as a result of: eating McDonalds/Kentucky Fried / Pizza Hut etc fast food; drinking VB/Fosters/XXXX/ Bundy and Coke and driving; domestic violence; walking around in the wee small hours when there are drunk sociopaths in your vicinity throwing punches; climbing ladders; going out in inclement conditions in your tinny; smoking; driving; flying; rock fishing; bush walking; using a quad-bike on your farm; using a tractor on your farm; bicycling; crossing the road; using your mobile phone while driving; being a small child behind your parent's vehicle in the driveway when it reverses; being in a bushfire zone when it goes uncontrolled than you are to be killed by Islamic-inspired ( or justified as such by some terminally socially-incapable nutter). And my list is just a scratch of the surface here. Religion, per se, is a philosophical statement - and there is - if you look at it closely - relatively little fundamental difference between the underlying tenets of most of the 'recognised' major religions. However, the organisational application of various streams of religion - broadly described as the 'Churches' - is about the solidification of political power. What we all are repulsed about by the excesses of ISIS now, needs to be viewed in the context of such times as the Inquisition, the Crusades, the Elizabethan persecution of Catholics, and on and on. The only damn difference, is the timing - i.e. our current perspective. As an old second-generation 'Australian' by birth and upbringing, of primarily Anglo-Saxon descent, (all of my grandparents were immigrants), I have been entranced and delighted at the diversification of this country's cultural influences. The Australia I knew as a teenager was constricted and constipated in its outlook; immigrants escaping the aftermath of WWII were thought of as mostly fodder for menial labour. Nowadays, I have a grandson who is half-Indian, I cook more 'Asian' food that 'traditional' Australian lamb chops and sauce, the wonderful people who look after my 98-year old mother requiring 24-hour care so well are a great mix of nationalities, I drive vehicles manufactured in both Australia and Japan, I buy sushi and kebabs and baklava from my local Mall. We will NOT negate the violence visited upon us by sociopaths using some perversion of any religious tenet as their justification for their action by banning/excoriating them: I absolutely believe that the best defence is the generation of a milieu in which the reaction of their peers will be: 'why would we kill our friends?' In my 60+ years of existence here, I have had two instances of unpleasant relations with 'Muslims' - but a whole lot more with 'dinki-di Aussies'. Any motorcyclist with long hair and a beard riding into a country pub in the 60/70's got abuse from the local yokels - Anglo-saxons to a fool. EVERY ethnic group has its share of ar$holes - and our community is no different. And, for my money, Hanson is part of the problem for the integration of all of the elements that make up our country now - and absolutely NOT, part of the solution. To see where we could be wonderfully headed, read Waleed Aly's stuff. HE is an Australian I provide as an example of what we CAN be, if we unshackle ourselves from narrow prejudice and illiterate and ignorant rants. I am glad that my grandson is growing up in a country that embraces such a person - and should repudiate Hanson.

A couple of years ago - well, actually, a few more than a couple - I decided to get back into riding after years away from it - the old 'family responsibilities, job, opportunity' crunch syndrome. I'd run a 400/4 Honda playing Agostini around Canberra streets for some years, and had heaps of fun on quite a few bigger bikes: the CBX1000, Duc Darmah and a few great runs on an octagonal-case bevel-drive 900ss, Squeeky GS 850, Yammy FJ1100.. I'd always yearned for a Viffer. Found an '86 - the first, lightest and arguably fastest.. in Rocket Ron Haslam blue, not the White Bike. In need of a little TLC - and when doing that, found just what a fantastic job Honda had done with it - (you will remember the stuff up with the cam and cam-chain drive of the Vf750R, for which the urban legend said Hoichiro Honda said: 'we will redeem ourselves') Urban legend says it sold at a loss; the quality absolutely everywhere on that bike is just fabulous; with nearly 100K on the clock, I changed out the headstock bearings and replaced the front fork seals and it rode like a brand new bike. All motorcyclists appreciate 'character'; the way a Viffer 750 lopes along below about 5k revs as a slightly urgent Ducati twin is restful, then above that, the cam hits and it just flies. I fell in love with riding again- then disaster - severe carpal tunnel in both wrists. Operations, but they've taken several years to actually get sorted, and my beloved Viffer sits awaiting my attention in the back of the workshop... but that story isn't yet over.

Seb - that looks good to me, though JUST stuffing more air in won't be a magic fix if it doesn't get to the the right places; testing will prove the pudding and the old adage of 'one change at a time' is a good one. Re changing the muffler: be cautious. If you are running a 2200C engine, it was certificated and the back-pressure figure for the engine was carefully tested; don't make up something that introduces an increase in back-pressure as it will affect engine performance. ( I haven't seen the test stuff for ASTM certfying but I imagine it has a similar requirement). That 'log' looks like a tin-can stuck on but a bit more work than shows went into it!.

seb: I think you are on the right track (but that's just my feeling - not to be taken as any sort of authoritative statement!) I assume you have looked at the Jab. engine install manual? (JEM2202-7, available from the Jab web-site, is I think the latest version). It provides quite a lot of useful info. FWIW - and I stress that this is my interpretation of general information provided to me by people whose knowledge is far better than mine and whose experience suggests they know what they are talking about, NOT any definitive statement of results for which I have figures to suggest I am correct - I consider that the early intake shape is pretty damn awful. The narrow outer ends of the intakes are only just getting into the effective area of blade shape for getting decent prop-blast flow from the prop. for starters. When Alan Kerr (who did the development and certification testing for the original 2200C engine) was looking at an installation of the Jab. 2200 for Boeing's prospective entry to the Australian Drone contract for the RAAF (which didn't come to pass, different story) he found that in a cross-wind, the downwind intake for the heads was actually flowing backwards! Worse for the 'downward-prop' side ( the PAX. side, in a Jab.). In other words, the prop blast effect was useless when stationary and at around idle revs. - the heads on that side of the engine were sucking the hot air from underneath the ram-ducts!. Now, put that into a FTF context: holding on a busy strip, lengthy pre-take-off check sequences with a trainee, then moving onto the strip and putting max. power/low airspeed for the next several minutes of initial take-off onto heads already damn hot - no wonder that FTF operation has had the worst run of Jab engine problems.. If you are thinking abut modifying your intakes, I'd be trying to get a bit more intake area at the outside edges to pick up more prop blast. This is what I have done with my revised top cowl: It's a completely different profile to the standard LSA55 etc. cowls (hence the necessity for a 'bulge' to clear the starter!) NO - I cannot say that it works - it will be many months before we get to flying tests - but it might give you some ideas you may wish to try.

Can we get across the actual definitions here: 'Certificated' - means has achieved approval to the standard of an ICAO-signatory authority ( FAA, EASA, CASA). An 'certificated' engine will have a TCDS. The testing is oversighted by the Authority - not the manufacturer. T he legal responsibility for the performance of the engine, rests with the certificating authority 'Certified' means the manufacturer has certified that it performs to the ASTM standard. Though the ASTM standard and the 'Certificated' standards testing (whether to FAR, BCAR or JAR/EASA) are similar they are not identical - and the MAJOR point is that the legal responsibility goes back to the manufacturer. In practice, there is little to choose between relying on 'certification' or 'certified' - providing the latter is from a reputable manufacturer.

Hi Seb - apologies for the tardy response, other stuff intervened.. I am absolutely NO guru - but I am fortunate to have access to some people who have decades of experience. I ask questions, listen to advice and then try to follow that as best I can. Something I have had drummed into me, is that there is NO 'guaranteed' answer. In the case of an engine swap (for instance) to a certificated aircraft, the end result must meet the original cooling performance (with allowances for an accepted operating regime for the 'new' engine). Ask any ex-CAR35 / current Part 21M engineer and you will be told that ONLY by flight testing can compliance be demonstrated. Why? - because it is simply not possible - even with current airflow dynamics modelling programs - how the damn cooling will perform in real life. There are too many fine variables for accurate prediction from best design principles. I believe you are well on the right track with your ideas, but only flight testing will tell. Re your anomalous cht reading - are you sure you've set up the MGL channel for the right probe? We're using two strato instruments for the engine test cell, and they do require attention to the set-up - but are pretty damn good when properly configured. We calibrated the cht readings from the probes ( CAMit probes) to the instrument using a special set-up, and it proved that they are within a couple of % across the entire range, using this set-up. It is a brass rod of 125mm diameter x 150 mm depth, heated by a stove element, with laboratory-grade mercury thermometers ( 2, for averaging), plus we used an IR meter just as back-up - and everything was damn close in readings. It looks hokey - but it will pass CASA inspection for FAR specification for calibration accuracy. WTR to your bottom-lip extension: the critical element there is that you achieve a decent negative pressure and extracting airflow in the lower cowl. A large lip at too steep an angle will stall and have a 'back-curl' effect that will choke off extracting the lower-cowl area. If you can modify it to have a rake of no more than about 15 degrees to the apparent air when the aircraft is in steep climb AND extend aft of the firewall, I think you will get better results. Combine that with a total air extraction of around 2.5 - 3 times the intake areas ( and you need to add to the head intakes the oil-cooler intake area, because it exhausts into the lower cowl.) For our own aircraft, we have decided to go right away from the original cowl - but that was in part because ours was built for the 1600 engine but used as the test mule for the 2200 engine, and our cowl was a lash-up. It says somethiong for the tolerance of Jabirus that it did 2700 hours as mostly a training-fleet aircraft - but it also chewed through engines too quickly. I believe a lot of that was from bad operation and lousy-quality maintenance by an L2 who I would personally not let to maintain a half-brick. What we are doing is most definitely a 'work in progress' - and has a research element involved - so more description would be useless to you.

Absolutely agree with KC (above)! I've built a few clubman- level sports car chassis (think Lotus Super 7, Caterham) and by comparison, they've been quite simplistic. Those who have followed this thread and thought about what HITC has been explaining, will appreciate the complexity of resolving lines of force within a tube structure, both for the 'normal' load case and the 'crashworthiness' load case. We old-timers may remember the famous Maserati 'bird'cage' chassis for their Le Mans cars - so-called because it was joked that a bird couldn't get out of them.. Personally, I really do not like the 'tube and riveted gusset-plates' joins methodology: it will work ok if well designed for normal loads, but unless it is really superbly designed, there is a real risk that in an 'exceptional' load situation, the joins will tear apart rather like perforated stamp sheets - and once that starts it only gets progressively worse and may leave short tubes flapping around to act as spears for the occupants. A fully monocoque structure bends (usually); a carbon-fibre structure will tear/shear if loaded adversely; a low-tech composite structure ( e.g. Jabiru) will also tear, but it takes a lot of energy to keep the tear going - it doesn't fracture as C/F will and some of that gets dissipated by flexing so the load gets taken out very progressively. A tube structure can take seriously large loads if the force paths are properly resolved. A good - and readily-available - example, is a Jabiru engine mount: 5/8" 4130 tubes - they look almost like straws... Great tip re using some copper sheet to dissipate heat from thin gussets - I've used heat sink technique for silver soldering but never thought to use it for welding!. Does it introduce any extra brittleness in the inter-granular cooling zone? Flying blind here ( little joke..) but I'd imagine that you'd want to leave at least around 2 - 3 times the fillet radius clear? I once did some filling of detonation damage to a Husquvarna racing bike 2-stroke head, and the bugger would crack at the edge of the weld pool until I set up a super-hot sand bed to bury the thing in instantly after welding (and pre-heated the entire head to stinking bloody hot before the welding!)

With due respect to all - cooling of an air-cooled flat engine is something of an arcane science. Ask any aero-engineer who has been involved in engine modifications/swaps/aircraft performance testing and you will find that it is a really, really tricky business to get right - and there is NO 'silver bullet' answer. Some months ago, I spent some time with a J160 owner at Camden, who has managed to tune his standard Jab. baffles and cowl exit lip just about to perfection. He's a seriously competent guy, and his project for that has taken him many, many months of research-level trial - even down to wool-tufting the internal baffles and having a borescope camera inserted so see what the airflow was actually doing. Then - running a proper test sequence for each change: climbs at various speeds in various ambient temps and at various revs; cruise performance etc. The degree of finesse required to get the standard Jab. ram ducts to work properly, is remarkable - and it varies between the sides. Then there is the cowl extraction set-up: too much lip at higher angles of attack causes a stall around the lip and reduced efficiency of extraction just when you need it most. And - the 'finessing' is in the area of millimetres, not just a bit of a thump with a mallet.. However - some basic principles still apply even to rather 'gross' changes. Basically, these are: A p-delta drop between the intake side for head cooling and the extraction side of at least 2.5" is essential. The cooling air needs to be at close to optimum pressure and velocity for the head fins to be really effective. Inadequate velocity will not provide adequate heat transfer; too much pressure is likely to cause stagnation at critical points - and the standard Jab. head bolt at 90-dgrees above the exhaust port is a major constriction for good cooling around the exhaust port. The standard Jab. ram ducts waste a considerable amount of the potential head fin area for cooling due to a too great velocity drop. Excessive oil cooling does NOT improve overall cooling performance and has serious adverse effects: oil should be running at close to 100C to boil off the sulphides. Only if there is piston under-crown oil cooling,is there any reason to provide excessive cooling capacity - and that should be moderated by a TOCA. Any opening on the top cowl is potentially dangerous: in the event of an oil leak, you will get oil mist on the windscreen and in the case of an under-cowl fire, you are dead in a very short time. Reducing the airflow around the muffler and exhaust stacks is extremely unsafe.

Geoff, the fact that you share the 'bad' stuff, is admirable. A good, accurate description of a situation that turns of to be less than 'optimum', combined with good analysis and very good conclusions, helps us all - well, certainly me, who has almost no power experience upon which to fall back. And - as with your detailed description of the 'smoking fuel pump' incident, may I say I admire the fact that you quite evidently kept the 'bigger picture' firmly in mind with your (presumably, somewhat instinctive, from your description) reaction to cut the power and save a hard bounce from becoming a bulk strip and prop replacement!. I have once - and that was enough - jumped into an airplane (glider) when I knew I shouldn't (heavy cold, tired, somewhat dehydrated.) I hadn't meant to fly that day but in front of a crowd of people waiting to fly, had been basically 'asked' by the CFI to take a glider up to facilitate a change of strip because the wind had shifted nearly 90 degrees and piped up. Suffice it to say that I got it back on the ground, but the next thing I remember after that was someone holding my wrist and shouting 'It's OK, he's got a pulse'. Adrenalin can only get you so far... and I had it burned in on that occasion that I do NOT want to hear: 'It's NOT OK, he hasn't got a pulse'.. I don't have the power flying experience to effectively contribute anything of value here - but glider experience is that you only have one shot at landing. Whether it's a routine circuit or an unexpected outlanding, we were trained that at 1,000 feet AGL in zero lift, the ground was where we were headed, so make that work. ( I have a couple of times climbed out from less, but only in serious lift e.g. a strong thermal coming off a brown field). Gliders have flaps and airbrakes, but you don't (usually) play the flaps, you keep as much height as reasonable and use the brakes and sideslipping to increase descent rate. You keep as much height and sensible airspeed as you can, right up to the moment you can afford to dump both because they are absolutely redundant. In gliders, you normally 'land short' - because it's a pain for everybody to retrieve a glider back to the launch point from way down the field. We get used to 'playing' the circuit height and speed. IF - because of this experience - you are left with uncertainties about your technique: can I suggest you try a few glider flights? You might find it very confidence-building to get the feeling that the aerodynamics is what keeps the damn crate flying - not the noise out the front!. (And if I sound in any way condescending - my instructor, who was also a gliding instructor - is patiently trying to get me to understand that the noise out the front is something I can use... after my first five or so circuits, he asked me gently if I was consciously setting up final on sideslip, or was it ingrained habit? -which it is..)

OK - I have no idea; certainly GA tends to prefer gascolators - I understand. Agree re any glass unit; a plastic unit in the engine bay would be a major fire hazard (and wouldn't meet any FAR requirement..), and I'm not aware of any glass-bowl gascolators - the ACS one isn't ( but also isn't all-steel, to meet FAR reqs. either..)

With respect to all contributors - my negative feeling towards paper filters is not because I've had any spectacularly BAD run with them, and I fully accept that many people use them very successfully. I've had a few, over the years, give me troubles in my cars/bikes, to the point where I always carried a spare. Most of the failures I had were due to bad lots of fuel - and if you've never had a bad lot of fuel, then I suggest you don't travel much in the more remote locations where (in days of yore, at least) the same fuel truck would carry petrol, diesel, and sometimes other stuff, to some small outpost.. I've had a plastic (Ryco-type) in-line filter crack, spraying fuel all around the engine bay. At the time that happened, I was running down a road (evacuating) with a bushfire nearby and approaching - and I think I possibly set the world gold standard time for replacing a fuel filter.. That's the sort of experience one does NOT forget. Motor vehicles, generally, get frequent use so the sort of build-up of 'gunk' from older fuel sitting in the tank/s for some time rarely happens. Modern EFI systems require both high pressure and provide large flow rates with returns to the tank which - to a degree - will dissolve bacterial 'sludge' build-up. Those systems act to ensure that the flow-rate to the injectors is well above optimum. If you are running a 4-6 psi system ( Rotax carby versions and all Jabirus), there's no excess pumping capacity to overcome a diminishing flow-rate due to gradual restriction of the filter and it's been shown that the flow-rates in Jabirus (at least) can degenerate to levels that produce a dangerously lean condition for full-power use. No doubt, every careful aviator checks the fuel after every top-up from the tank drains and on every DI. May I point out, that that check does in no way check the status of any paper/microsphere-type filter? And - for a top-up out somewhere remote, if sediment or other crap is present in the fuel, it may not have settled out to the tank sump when you do your check. A gradually clogging in-line filter has - by its nature - a diminishing area passing fuel, so less and less contamination is required to block the filter as time passes. Every time you check the fuel coming from a gascolator, you effectively clean it ( and yes - that's not perfect, it should still be checked every 100-hourly at least).. BUT: if there's crap in your fuel, it will be pretty quickly apparent. I've added an ACS gascolator to our Jab. rebuild install, at a cost of a bit more than $100, from memory. It's a neat little unit and not very heavy, and I'll be flying with more confidence than using a paper filter that - IF it fails - will dump me on the ground. I should add: the gascolator installation needs to be properly worked out, so it cannot contribute to fuel vapourisation if in the cowling area. But - we all know that a proper fuel delivery system is essential to our safety - don't we? We don't just trust to stuffing fuel in the general direction of the engine and hoping that it all works out OK - do we?