Daylight On Dreamships Parts 7, 8 & 9


By Fred Lindsley

(This article is from SAAA's "Airsport" magazine March/April 1989 edition)

In this continuing series, written for Airsport readers, Fred Lindsley contributes a two-part article on engines. This first part is largely based on established data which is readily available, or apparent to perceptive observers able to distinguish between realisable dreams and pipedreams.

The subsequent second part will deal with practical aspects of engine installation design.

Power And Positive Thinking

Take a few mature dry seeds from assorted plants in your garden or adjacent waste-land (assuming your wife agrees that there is any noticeable difference). You do not need many, just enough to cover a two cent coin, and if some are so small that they are hard to see so much the better.

Scatter the seeds in a test plot, cover with soil and keep moist. With any luck they will do what seeds have done since time immemorial. They will sprout. With the majority of plants the sprouting will comprise two shoots from the seed.

No matter how randomly the seeds were scattered and which way was “up”, a tiny little automatic pilot inside each seed will detect gravity and steer one shoot downwards. By a sort of reverse polarity the other shoot will develop antigravity, and you will be pleased to see that your talent as a gardener is at last being recognised by nature.

Nor is that all. That tiny auto-pilot is part of a miniature computer which, given time, is programmed to grow the same sort of flower or weed and plenty more of the same sort of computerised seeds. And with not a soldered connection in sight.

There may be exceptions of course. If the original seeds came from a grafted plant, like a rose, the seed’s memory banks may retain sore traumas of an operation akin to ritual circumcision. These unhappy remembrances may make your seedling obstinately revert to something different from what you had hoped. No computerised rose without a thorn.

The new reader to ‘Daylight on Dreamships’ may wonder what this has to do with amateur built aircraft and, more to the point, their engines, which is what this article is supposed to be about.

Perhaps more than may be immediately apparent. If it has started you thinking in a new way about what has up till now been considered elementary observation, blindingly obvious to everybody, then we shall have taken an essential first step towards getting some reliable and economic engines for our amateur built aircraft.

If you agree that there may be more to the basics of gardening than the practical process of digging, plus the excitement of looking at coloured packets of seeds, we are off on the right track. If you accept that there are never any quick solutions in agriculture or horticulture (not even with mushrooms) further progress is made.

Exercising such positive thinking, with a mind firmly focused on your requirements and ambitions, may indicate some cost/benefit advantages for your garden (or engine). One of which is that some worthwhile stay-at-home reading may be a great deal more useful, and cheaper, than overseas trips to the Chelsea Flower Show or the Hollywood Rose Bowl.

The plant geneticists are still working on the phenomena outlined in the opening paragraphs. They are continuing the tradition of an eminent pioneer whose work benefited people in all continents. A large amount of his research, chronologically and in character, paralleled the earlier days of aviation.
Luther Burbank’s death occurred the year before Lindbergh flew the Atlantic. He thought about things in a different way too.

A General Perspective

“No aircraft is better than its engine” is an old and fundamentally true statement. Failure to adequately recognise this dictum may have resulted in less progress from the ALADC (Australian Light Aircraft Development Council) than had been hoped when it was inaugurated more than two years ago. One might have expected more tangible results from a committee of 21 extremely able and competent specialists.
Perhaps there is still some substance in Winston Churchill’s observation — “If Moses had been a committee the Israelites would still have been in Egypt ”.In ALADC Report No. 15 of October 1987 it is revealed that $949,815 of taxpayers’ money had been granted to four aircraft projects — $408,750 of it to Queensland — but not one cent towards any of the seven engine projects listed. In a later report of more than a hundred pages, engines barely got more than a paragraph’s mention. This may suggest some slight lack of balance in the appropriate perspective.

Although our objective is dreamships, we do have to maintain a certain amount of realistic perspective too. For what can be broadly described as “our sort of engines” it is necessary to look at what has been done in order to reasonably predict what might be accomplished in the near future. This means consideration of some historical facts.

From 1919 to date, and excluding motorcycle and car engine conversions, about 185 different types of engine have been produced for light aircraft in the up to 200 hp four-stroke category. Meaning engines that you could actually buy if you had the money. 1919 was selected as the starting date because that coincides with the commencement of civil aviation in a meaningful way and is also the date of the first viable entrant to the market.

Some of the 185 have been manufactured in quite large quantities and although some of their names may lack familiarity it may come as another surprise that Soviet Russia currently produces more jet engines than all the rest of the world combined. Where dates are quoted below they are market entry dates. Some also remained in production for decades without significant change.

All were designed by suitably competent engineers. The idea of the local blacksmith making good in the big time is just cherished illusion, which needs to be abruptly removed from the heads of those credulous persons who subscribe to its promotion.
There have been 59 radials, the last USA one in 1938 and one subsequent Polish engine in 1953.There were 61 in-line engines, including 5 Vees. The last one from the USA in 1941 and two subsequent examples in 1948 from France and the UK .

The opposed engines (perhaps including some 180 degree Vees which are not quite the same thing) eventually and remorselessly pushed the radials and the in-lines out of the picture. There have been 65 of them, the most recent — and current — the Continental Voyager 200 and 300 series.

The new Voyager engines are the only liquid-cooled engines in a 70 year history. With their compression ratio of 11.4 it could be that low specific fuel consumption is the objective. To get this means that the engine has to stay in tune like a Stradivarius in a violin concerto. Perhaps circuits and bumps in club training aircraft will give a reliable guide to future economics.

Where aero engines have been produced by established car firms it is interesting to see how rapidly the designers divorced themselves from the parental disciplines. Examples are Continental (who in the 1920s, when they started on aircraft engines, were the biggest manufacturer of automotive engines in the world), Fiat, Napier (their six-in-line aircooled Javelin went into early Percival Gulls), and Renault.

Of these 185 engines, 14 had reduction gears. One of which was our curtain raiser, the Mercedes F7502 of 1919. A two cylinder opposed engine of 880 cc giving 20 hp at 3000 rpm and equipped with a planetary reduction of approx 3 to 1. In 1922 it set a world altitude record for two-seater seaplanes.

However the history of geared aircraft engines in the smaller powers is not very inspiring. The Continental Tiara series of 1972, although of higher power than in this review, are perhaps something that Continental would prefer to forget. Only two geared engines seem to have emerged as noteworthy, the 9 cylinder Salmson 9ADR of 2.98 litres, ungeared versions of which were installed in Bert Hinkler’s Ibis, and the 7 cylinder Pobjoy series.


Based on the Pobjoy “P” of 1928 the “R” of 1931 was developed. This engine was installed in most Comper Swifts, including the one flown by Arthur Butler on his record breaking UK to Australia flight in November 1931. These early examples of the now popular “high revs with reduction” configuration culminated with the Niagara V of 1937. 142 hp at 4600 rpm from 3.13 litres for a weight (with prop hub, cowlings, exhaust and electric starter) of 185 lb.

Fifty-two years ago. Like so many other projects the outbreak of war and the death of the designer curbed further production and development. I have recently had a letter from my old colleague Ron Saywell, now retired from R F Saywell Ltd, who was quite a Pobjoy specialist. With adroitly placed platform steps Ron and I would manually lift these Pobjoy engines in and out of Short Scions and fiddle with the engine mounting bolts. Ditto from floor level with Monospars.

Where reduction gears are concerned there is some evidence that they, and propellers and crankshafts, find it hard to qualify for superannuation benefits in the overhaul workshop with less than three power impulses per revolution of the crankshaft. The belief that crankshafts, even on multi-cylinder engines. rotate as smoothly as three phase electric motors is a delusion. Running this delusion close are the beliefs that motor racing and the modern family sedan represent a vast reservoir of untapped aeronautical expertise, which has been inexplicably overlooked by the aircraft engine manufacturers in their search for technical know-how.

Such misbeliefs are increasingly being espoused outside our recognisably competent SAAA membership, and may in future present a problem to our well being. The situation is that witchdoctors quite easily convince themselves that they can demonstrate the skill of brain surgeons, without any study, by the simple process of buying a chain-saw.

This article is no deviation from the conventional ‘Daylight on Dreamship’ series.

It is however aimed at a wider field than the dreamship devotees because the subject is a serious one and its portents could have some bearing on our future.

Amateur aircraft building in Australia , embracing a wider range of technology than any other leisure time activity, has a more than 30 year history of satisfactorily conforming with an essentially stable system of requirements. Compare the recent 12 year history of other requirements which the ultralight advocates claim have become increasingly restrictive. Why?

We need a lively apprehension that immature engine activities carried out and totally dissociated from SAAA could nevertheless result in the introduction of as yet unforeseen requirements, technically and economically more restrictive, which could well affect SAAA existing achievements and our future progress.

Be warned. Those silly men in the fable, instead of chastising the boy who cried “Wolf’, would have been far better off studying aviation where every false alarm from warning systems demands serious attention. (Ask any airline pilot.) Applying the impartial logic of engineering, as distinct from enthusiastic mechanical tinkering, leads to three inescapable conclusions. Those foolish men were incompetent because they nominated the wrong boy, the boy did recognise a wolf when he saw one — and the sheep were slaughtered.

The Motor Racing Background

Formula One Grand Prix racing is now probably the biggest circus seen since the Vandals and Goths vandalised the TV transmitters in ancient Rome. The invading Vandals and Goths naturally wished to substitute their normal down to earth programmes of simple pillage and rapine.

After a five year lapse prompt action was taken to revive motor racing following the cessation of hostilities in 1945. Coincidentally, at the same time, approximately 195,000 exhaust turbochargers previously warmed by a modest 252,500,000 horsepower slowed down to a halt. They had logged quite a bit of service in B17 Fortresses, P47 Thunderbolts, B24 Liberators, B29 Superforts and P38 Lightnings.

Some 30 or more years later it was inevitable that the G.P. aficionados with their high velocity advertising signboards would eventually stumble into the discovery of turbocharging, and they got their first win in 1979. Much has been made of power outputs per litre, and boost pressures which actually did not come within cooee of the 5.7 atmospheres previously used on some diesel turbo blowers.

Not surprisingly plans are afoot to aquaint an innocent like me, untouched by speed-shop gossip, with the latest state of the art developments in the internal combustion engine. Turbos. Which Lycoming and Continental have been hanging on their higher power eng­ines for a good many years, and not without some traumas either.

In 1983 the Formula I Renault turbo was giving 580 hp from 1.5 litres at 1.8 bar for a weight of 397 lb, 387 hp per litre and 0.6785 lb per hp.

In 1931, 52 years earlier, Rolls-Royce had got their “R” engine of 36.7 litres up to 2783 hp for a weight of 1630 lb. It had a normal single speed supercharger at 72.3 inches of mercury of approximately 1.45 bar above atmosphere. This engine was basically a standard R-R Buzzard of 925hp and 1927 vintage which Rolls, some reluctance, souped up for the Supermarine racing seaplanes. Winning the Schneider Trophy and later setting the world airspeed record the Supermarine S6B was instrumental in the designer, R J Mitchell, later developing the Spitfire.

The Rolls-Royce “R” engine, of which a number were built, was quite tractable. It would idle at 475 rpm although it peaked at 3400 rpm. Nor was it any flash in the pan. It later went on to take the world water speed record and, twice, the land speed record. A remarkable and versatile aero engine.

So the “R” engine gave a miserable 75.8 hp per litre, but being designed for aircraft it was right in the right places. Power for weight. It came out at .5857 lb per hp.

Thus you see demonstrated the racing car delusion. From an aircraft viewpoint the turbo Renault is 15.8 per cent heavier than the “R” of half a century earlier. In fact it is worse than that because the Renault still needs a massive heavy intercooler to get any useful work out of it, and the “R” engine weight includes the encumbrance of a gearbox transmitting more than 2700 hp.

Actually the turbo Renault, on a power weight ratio comes out more than 3 per cent worse than the normally aspirated 3 litre Cosworth. Do the boys at the speed-shop really want to know this?

The racing cars then discovered topsy-turvy aerodynamics with upside down wings and what they, for a time, called “ground effect” cars which, of course, was totally unrelated to the low induced drag from ground effect which has been a lifesaver for so many partially disabled military (and note a few civil) aircraft.

A weird system looked at dispassionately. Fit this, ban that, change the rules, alter the weights, and make things a nightmare for the car and engine designers (who are extremely expert at their jobs). Spend a million dollars — and in the final analysis, on the track, the most important contribution seems to come from the laboratories of the tyre chemists.

You see racing car magazines where in effect they are drooling, with three places of decimals, about the low drag coefficient of some streamlined rear wishbone strut. Which is photographed— in colour of course — alongside an enormous rectangular tyre with a drag coefficient requiring as much power to push this tyre down the straight as it does to propel a pantechnicon at high speed down the Hume Highway. Can it be that the magazine readers are the real clowns in this circus?

After 10 years the Formula One controllers have now dumped the turbos. Did they try to advance their technology by trying to see what they could screw out of a one litre engine? Oh no, they have opted for a normally aspirated 3.5 litre limit. So the power will start an upward climb, and before you can say “chicane” they will be changing the rules again.

The general ambience of Formula One seems to apply in other branches of motor racing. The supporters of the sport’s alleged technical superiority appear to have a sort of tunnel vision which sees only a chequered flag. They seem reluctant to entertain any developmental programme which takes longer than a pit stop.

Their attention is concentrated on a two hour engine life where winning is everything. For reliability just cast a glance over a few years detailed race results. It is seldom that more than half the starters finish and when the non-engine causes are eliminated you are still left with an astonishing list of extremely short life engines rather expensively produced by top-line experts in the art.

Are these people really capable of leading us into the promised land of cheap, and above all, reliable aero engines? I would suggest that their psychological outlook is the diametrical opposite of what we need.

As quoted recently in the press, an Australian driver has returned after witnessing tests of the new 3.5 litre G.P. cars. He announced that next season the spectators will need earplugs.

Such environmental sensitivity! Who could be eloquent enough to do such sentiments justice? Assuredly, by these signs shall ye know them.

The Family Sedan Background

Here, presumably, we are all on familiar ground providing we distinguish between motor cars, which are automotive engineering, and driving them, which is an altogether different activity.

For dreamships and aviation applications it is important to base our thinking on what might be an unpalatable reality. The current road toll is approximately 2900 fatalities and 17000 hospitalisations per annum. The majority of whom are completely innocent parties, many of them infants. All at enormous cost to families, the economy, the medical, police and legal systems. We shall return to this aspect later because it has a significant relationship to airworthiness and engines.

“That’s the price of progress, isn’t it?” “It’s never been any different”. “What can anybody do about it?”. Those who produce the standard explanatory phrases may fail to see that there is a connection with airworthiness and the recently introduced charges we are complaining about. If they fail to perceive this, they will almost certainly fail in their attempts to convert car engines into sensible and safe aircraft engines.

Excluding sports specials, of which there have been hundreds, 47 different makes of Australian car have been produced since 1919, 26 of them since 1945. So there is no shortage of engineering talent. It is true that the number has now diminished to a handful, the majority of which sound like a samurai roll of honour, but this is just another fact. Engineering has to deal with facts, not misguided hopes and suppositions.

Nobody has ever taken a car engine off the production line and put it in a satisfactory aeroplane. It can’t be done, and that’s another fact.

It has to be “converted”. Most of us have, or know somebody who has, an engine not doing anything and just itching to have a propeller stuck on one end or the other. Have you met anyone who wants to buy a new engine from a car manufacturer and then convert it?

When you take that engine out of a car and put it into an aircraft it becomes a very different animal. For about 23 very valid reasons. Even experienced motor mechanics can seldom list more than a handful of the reasons.

If you start making out your own list you will have taken the most rewarding step in engine conversion. You will have started to think about the real problem - with a pencil in your hand. If you can identify at least twelve reasons, send them to me and I will send you a complete list with my compliments. It will help everybody if those who are disinclined to compile a list will please desist from droning on about the Shake, Rattle and Roll car engine conversions they have seen in overseas magazines. This sort of talk is merely time-wasting toying with a quite serious subject.

Car engine conversions have a long and, with one notable exception, a not particularly inspiring history. In 1936 the USA Dept of Commerce for Air (fore-runners of the present FAA) provided $1,000,000 — a lot of money in those days — to find out if an airplane could be built which would cost no more than a medium priced automobile. They kept out crackpot inventors by awarding contracts to people who had sensible drawings and proper engineering predictions.

There were quite a number of worthy contenders all of whom used automotive conversions. Among them were the Fahlin which used a Plymouth Six of 80 hp with a 2:1 reduction. This conversion was the first to be certificated in the USA, after a 100 hour endurance test at full power the previous year. The tailless Waterman (see photo) used a Studebaker Six. Only one of the whole entry saw what was a very limited production, the Arrow, a two-seater with an 82 hp converted Ford V8, an empty weight ratio of 70 per cent and a recorded payload, with full tanks, of 198 lb — or two somewhat slender people.

So the taxpayers’ million dollars didn’t produce anything viable for the taxpayer to fly. So Continental, Lycoming, Le Blond, Menasco, Warner, Fairchild, Jacobs and Kinner all reached the conclusion that liquid-cooled engines and particularly the products of the huge car industry were not going to make much of a dent in their markets. Just as well. Their air cooled engine production capacity a few years later was scheduled for urgent wartime contracts.


The Ford Model A, much beloved of Pietenpol enthusiasts, also became a certificated engine and was installed in the commercially produced Wiley Post biplanes, although in a different conversion to Bernard Pietenpol’s.

The catch with the million dollar babies was that they had poor performances, notably on climb, and required a lot of aeroplane to carry the extra weight. This meant more materials which even in 1936 were not free, so the aircraft were not cheap either. Nor would the conversions have been, even on a production basis.

Aviation is a very weight conscious numbers business. Even today in 1989 for any given power it is doubtful if a liquid-cooled engine installation will weigh less than 30 per cent more than its air-cooled equivalent. Bear in mind that any specific aircraft type is still stuck with its original MTOW (Maximum Take Off Weight) for performance and strength reasons. The best conversion to start with is converting the toolbox into a calculator.

Now I’m 100 per cent in favour of car engine conversions for our sort of aircraft, as previous writings should support. On the other hand I am sceptical about the motor car buffs who hope to solve all problems by wishful thinking because it obviously is “Oh-so-easy” and “Those aircraft people haven’t got a clue about putting four barrel carbies on engines designed for something else”. Because a very real danger to our future exists.

Those hopefuls of the “Let’s stick a prop on this engine” persuasion are, of course, perfectly entitled to run their cobbled up conversions on the ground until they melt, disintegrate, or the neighbours call in the police. Unfortunately, unlike modifications to motor cars, they can not be tried out by a quick drive around the block or, should there be scruples about insurance, on private property.

It’s just that 70 years of aviation history convincingly proves that there is no way of properly testing their engine until they conduct a thorough engineering programme of flying the engine in an aircraft.

This means rules, regulations. CAOs, paperwork and responsible liaison with CAA.

Any attempt to circumvent this system by smart-arse subterfuges may result in one of two things:-

Initiate another HORSCOT report. Incline the authorities towards introducing restrictive action, just to make sure that they are not again going to be embarrassed by another HORSCOT report.

Liquid-Cooled Engines

Over the years that I have been contributing random writings to Airsport I have nursed a secret ambition. To achieve a world scoop on a technical breakthrough. Complete with the now mandatory token headlines, “Another Queensland First” and “Billion dollar export potential”.

This was going to be the revelation that the Sunshiners had at last perfected their liquid-cooled lawnmower. Just what I need for our warm climate and, as an extra bonus, I could make a billy of tea when the lawn was done. After many years I am still waiting.

There are liquid-cooled internal combustion engines in boats. Also on pumping engines alongside river banks. There are no liquid-cooled engines in cars and one of the very few in aircraft featured in Rolls-Royce research.

Before and during World War II R-R operated a civil registered and wooden-winged Heinkel 70 as an engine test bed which carried a large coolant tank. An experimental engine would be installed in the nose (the HE 70 was single engined) and flight performance figures logged, allowance being made for weight change as coolant was pumped into the engine and exited as a trail of steam behind the aircraft. With the more powerful R-R engines this aircraft achieved some remarkable level flight speeds.

The engine would then be reinstalled plus its cooling system as in, for example, some bomber’s nacelle complete with Merlin and radiator. The aircraft then went through the whole performance drill again. Any difference in the figures was due to cooling drag from the radiator.

A large amount of useful data was obtained. When Rolls were asked what a Merlin might do in a P-5 1 Mustang the boys with the slide-rules predicted 431 mph at 25,000 feet. When the prototype conversion was flown a little later, as the ‘Mustang X’ in October 1942, they got 432mph. Like all the other Mustangs, and motor cars, it used air to cool its radiator.

From time to time people say “Just look at the Merlins in the Spitfire”, thereby unwittingly putting their finger on potential problems with wet engines in our sort of aircraft. When the Hawker Fury with the Kestrel engine went into service in the early 30s it was the first British liquid-cooled first line fighter since the SE5A of World War I. Rate of climb was most important for fighters, which requires excess horsepower (see earlier Dreamship articles) so the fighter designers were always looking for the biggest power package they could obtain. So the liquid-cooled engines were always big engines. There wasn’t an aircraft engine manufacturer in the world who would waste a moment’s time making small wet engines.

Fighters were basically gun platforms. As it was nice to see to whom you were shooting at before they shot at you, the needle nose of the liquid-cooled engines tended to be favoured by purchasing commissions influenced by air marshals with memories.

At precisely the same time the civil airlines were divesting themselves of liquid-cooled engines as fast as they could. After 1930 only one notable air­liner was designed to use liquid-cooled engines. The wolf-in-sheep’s-clothing Junkers 86, secretly designed as a bomber in 1933 to use two Jumo diesel engines.

The civil airliner version was exported to eight countries and one with Jumo diesels was purchased for an Australian airline. But few of them had the diesels. They nearly all had air-cooled radials. South Africa purchased 17, to be powered by Rolls-Royce Kestrels. The first six were powered by the Kestrels but they were not delivered until they had been re-equipped with Pratt and Whitney radials, as were the rest of the contract. Ironically the first military Ju86 had Siemens radials and the second, like most of the 800 built, with BMW radials.

That 1933 design was not quite the end of liquid-cooled engines in commercial airliners. Doubtless some Airsport readers, particularly if they had anything to do with engine maintenance, will remember one or more of the post-war airliners which used Rolls-Royce engines.

The Avro Tudors. Yorks. Lancastrians, and the Canadair 4 which was a DC4 with Merlin engines. Their short life on regular airline service and eventual demise was not accompanied by any noteworthy expression of regret from airline accountants.

In cars the liquid-cooled engine has several things in its favour. The first is that weight is not a problem if production, as in castings, is cheap. Cars, like steam locomotives, cannot be made too light because they lose wheel traction. Liquid-cooling is very much quieter; if you want a cheap firebell you always look around for an air-cooled cylinder. However, in aircraft, radiated mechanical noise is a small proportion of the total decibels produced by propellers and a lack of enthusiasm to use automotive muffler systems. Consistently good castings combining cylinder blocks and crankcases can be made in cast iron which also gives a cheap cylinder bore. On the other hand no aero engine designer has used other than light alloy castings since 1914. And, of course, the auto people from time to time get spasms of using the aircraft aluminium or magnesium casting alloys, but without the trouble of figuring out the best way to accommodate a reduction gear.

Because of the need for sustained low airspeeds the obvious aerial candidate for the liquid-cooled engine is the helicopter. Its history as a practical vehicle goes back to 1936 and the number of different types since produced is very large indeed. How many have had liquid-cooled engines? Perhaps it’s time the cargo cult people did a little bit of painless research to support their somewhat dog­matic beliefs.

What perturbs me a little, and it’s not entirely because I am in an isolated backwater because I do get letters and phone calls, is that hardly anybody gives any consideration to radiators. There seems to be a general idea that something suitable will be found at the local scrap yard, when the time comes, and somewhere will be found to stick or hang it on the aircraft.

This is chequered flag thinking carried beyond naivety. In the mid 1920s the US Navy publicly announced that they would no longer have a bar of liquid-cooled engines in their aircraft.

This gave Frederick Rentschler his big chance. He talked a Connecticut machine tool company into supporting his ideas. They set him up with three colleagues in a tobacco warehouse where they designed and assembled their 9 cylinder air-cooled radial. It first ran on 29-12-25 and subsequently passed its Navy qualification test. It gave 450 hp, was named the Wasp, and powered the first Vought Corsair, the 02U-1 of 1927. Pratt and Whitney became famous and did not lack prosperity either. The US Navy and lots of other people bought P & W engines.

Navies have never had much joy in recovering even a few nuts and bolts from their forced landings which tend to come expensive. The point is that the US Navy’s liquid-cooled problems ironically launched some of the best air-cooled engines ever made.

Another slightly perturbing thing with the car engine conversion enthusiasts is that some of them seem to have neither the faintest idea about, nor any interest in, the exhaustive and demanding test programmes which the car manufacturers impose on their engines.

Such programmes are usually even more severe with aircraft engines, no matter how they are cooled. You can safely reckon that for every hour spent on the factory test-beds by Rolls-Royce, Daimler-Benz, Fiat, Alfa Romeo, Alli­son, Junkers and Napier that far more hours were spent in flight testing and getting the bugs out of the installations. Cooling deficiencies being high on the snagsheet.

The experts had immense problems even when they had enormous priority resources because they were fighting a war. It took three years to eliminate the Mustang’s cooling problems, from 1940 to 1943. Identical marks of engine would behave entirely differently if installed in a different aircraft, and sometimes in the same aircraft with a different propeller.

Don’t be dismayed. You too can solve any problems, but only by getting your thinking out of the automotive rut.

Before anyone dashes into the amusement park with shrill cries of kiddy-car joy, just pause a moment to reflect. People have been there before you. They know the survey plans and where the plumbing pipes, electric power/reticulation and the fire hydrants are located.

Miracle And Short Life Engines

Bentleys at Le Mans and TT races where a foreign motorcycle was a head­line-making rarity had some influence on my impressionable years. This is a good opportunity for paying a tribute to subsequent mentors, so many no longer with us, whose advice and guidance were educational. Representatives of companies and people who had spent years in design offices or test-beds, who gently but firmly steered my outlook out of hotrodding. (It was more genteely called “Tuning” in those earlier days).

The message of those experienced advisers gradually sank home. The manufacturers usually did know best. They were constantly trying to improve reliability. It was unlikely that anyone could improve on their most recent printed information. And that the most important thing in the world about any aero engine was that the damned thing kept going round.

Nevertheless the images of Bentleys and TT bikes encouraged the ready reception of news about any new engine development. Because an impecunious motorcyclist at the push of a throttle lever (before twist-grips) could conjure up visions of untold power at — and this is the important point — such miraculously low cost that even I could afford it whenever it was offered for sale.

So I’ve been reading about miracle engines, always vaguely implied as being available next year, for more than 60 years. Everything from engines made of calcified bird-droppings to free-piston engines fuelled by burning chopped straw. With the inevitable diesels and rotating engines regularly featuring in the mirage about every 3 or 4 years.

Now these miracle engines do have a place in the dreamship scheme of things. Right where they always are. As graphic illustrations — never photographs — on the front of magazines with large circulations and huge advertising revenues. Because they publish lots of do-it-yourself things you know you could build if you didn’t spend so much time reading the advertisements in the magazine. Commercial dreamfarming is a business.

A fair way behind the miracle engines but popping up for attention from time to time is the short life engine. “Us amateurs only fly about 50 hours per year so we don’t need a long life engine”, or “My Sodyutu conversion is wondrous to be­hold and the same engine in a car has done ten million kilometres in an & out of the crater on Fujiyama without a spanner being laid on it. All I want is 300 hours overhaul life”.

An admirable idea, agreed. But unless it is merchandised a bit differently to the way I think I hear it advocated, it is going to be very hard to sell and may even rebound on all of us,

The problem is one of philosophy. In an earlier section it was mentioned that more than half the road toll victims were completely innocent parties. The implication being that many car drivers tend to accept this as normal or virtually impossible to alter for the better.

When the conventional aircraft appeared on the scene we had, for the very first time in human history, a form of transport which could not be slowed down or stopped to rectify whatever might be amiss. To a significant extent it was uncontrollable and this led to some changes in conventional thought. One of them is that airworthiness requirements are basically formulated to protect innocent parties. People who dwell in Scottish villages, passengers in airliners which may inadvertently descend on motorways, and children in schoolyards in the vicinity of which your amateur built aircraft may fly.

Following World War I concern about the number of fatal accidents in unregulated aircraft, often operating as “aerial taxis” in various parts of Australia, resulted in the Air Navigation Act. This became law in March 1921, created a Civil Aviation Branch, and in its various diversity of regulations we have been stuck with this system ever since. No matter how it might change its name, it is not going to fade away.

Any attempt to bend this system to the Ford Falcon, Commodore or what-have-you way of thinking is doomed to failure. It is opposed to the aviation regulatory processes of nearly every country in the civilised world. If you do not care for wild elephants, camels or horses you have two basic choices. The first is to get out of zoology. The second is to study zoology and, with some patience, you can not only get these animals eating out of your hand but you may even get some useful work out of them too.

Just, for a moment, try to look at things from the opposite side of a desk in Canberra. As a very generalised observation, aircraft engine overhaul lives are not based on the safe time before a piston swallows an exhaust valve. The life is based more on the operational time, with scheduled maintenance, until. a nominated percentage of rated power is lost.

Nor is it quite as simple as that. Although it does not yet apply here, in the USA some certificated engines now are subject to a formula which includes inoperative calendar time. This, in an extreme case, could lead to an engine logging its whole overhaul life simply by being unused in a hangared aircraft.

Additionally, in both civil and military aviation, most aircraft, component and engine lives are influenced by statistical analysis techniques, a subject quite well covered in a number of readily availab1e aviation books.

Suppose my Sodyutu conversion does 598 hours before I make the sad and expensive discovery that I forgot to top up the oil. But your Sodyutu does only two hours before it flings a con-rod through the crankcase. Can we phone up somebody in SAAA asking them, on our behalf, to persuade CAA into granting a 300 hour overhaul life?

As agreed, there is nothing wrong with the short life engine concept. But, in the words of the old song, “It ain’t what you do, it’s the way that you do it”. The professional and long established procedures work best for amateur built aircraft and engines. Since few of us are even professional motor mechanics or LAMEs we are on very shaky ground when making a case for preferential treatment. The “I know all about car engines” attitude may be counter-productive. It may be translated as “I know sod-all about aviation”. Have a care. We need ADs (Airworthiness Directive) on uncertificated engines like a hole in the head.

Wot Merv Sez

People interested in amateur aircraft building often have a mate who has a friend who claims to know the intellectual giant who truly knows all about internal combustion engines.

This somewhat distant genius is invariably renowned for some remarkable qualifications such as:-

a) Years ago he invented a carburettor enabling cars to run on tank water which (you guessed it) was suppressed by the ganging up of those wicked oil companies; or

b) He has a corral full of flatulent kangaroos. Each day he puts two of them in the boot of his car and until sunset does the rounds of his property, using natural gas; or

c) Both a) and b) above plus two more. By holding an active plug lead he can diagnose every ignition ailment not immune to Ohm’s Law. And by putting his thumb over a disconnected injector he can, within a few minutes, rectify the most recalcitrant diesel engine. (He also invented the pressure spray hypodermic.)

This is the legendary Merv Uttaclott, boss of the billabong, maestro of the mulga, and patron saint of the Sunshiners. All contact with him is by landline, CB (if you have the jargon), radio telephone or optical cable. It is not a bit of good writing letters because Merv hasn’t much time for reading. He is not an SAAA member because he sees no point in building a legal registered aeroplane when he can build an illegal one out in the bush. On which he has worked for many years, enjoying every minute of proving to himself that he is defying authority and which, fortunately and largely due to Merv’s diabolical improvisations, will never fly.

Merv is also the Commanding Officer of the SS Brigade and, this is the not so funny part, has faithful followers in all States who are not swelling the ranks of SAAA either.

The SS stands for socket spanner. The firm belief is held that all problems, design or constructional, airframe or engine, can be solved by the gospel according to Merv. Just apply a set of socket spanners, a MIG, TIG or PIG welder, and a six inch copying lathe. Actually a normal standard lathe but it is used only for making things “to fit” or “to pattern”. You can be sure that ball-bearings get a non-existent interference fit in their housings.

Lurking as a grotesque power in the land, Merv’s aeronautical heroes are the Montgolfier brothers who pioneered the medium on which so much of his conversation depends. His disciples regard his every utterance as holy writ. His masterly pronouncements claiming instant solutions to every aviation problem - ‘‘Stands to reason” - ‘‘Just obvious commonsense, isn’t it?” - make everything sound so easy. His SS Brigade banner carriers can buy expertise in one day; all they have to do is to bring a fortune in machine tools in contact with the raw materials found under the bench.

Merv Uttaclott has the primary qualification essential for arousing admiration among his acolytes. He has never had to earn a dollar in the manufacture, maintenance or operation of aircraft.

Who needs drawings or books or figures when you know you were born with practical constructive ability? Just like the birds who build nests, the spiders who weave webs, and the mason wasps which have crawled through the drainage eyelets in an aileron and are cunningly altering the mass balance. Are they using any of those arty-farty formulas?

Our long sought self-administration is impending, so let us get it straight. Wot Merv Sez is rubbish. Much is misleading or expensive rubbish and some of it is dangerous rubbish. Merv and his minions may be outside the scope or control of SAAA but their potential to do future harm to our activities is not small. The SS Brigade do not want to be reformed because that would shatter their proudly held misbeliefs. Almost the only way to guard against their capacity for future mischief is to frequently apply the magic spell that may deter them. Ridicule.

When we are on our own we must be very sure that the technically blind Merv Uttaclott does not, like the blind Samson, bring the whole edifice down around our ears.

What “Boss” Kettering Said

Charles F Kettering (1876-1958) was an outstanding engineer.

Although sometimes imagined as one of those self-taught grass-roots token engineers made popular in fictionalised writing, he actually graduated from Ohio State University in 1904. As a young man he developed the first electric cash register, the electric starter for cars (initially known as the Kettering starter) and improvements in car ignition systems which set the pattern for decades.

From 1919 he headed the Central Research Laboratories for General Motors and was a GM vice-president when he retired in 1947. He initiated research in many fields including early work on fuels, the introduction of tetra ethyl lead, high compression engines, refrigerants, auto finishes and the first railroad diesels.

He had a lifelong interest in aviation, flew his own aircraft, and at one time had logged more hours than any other amateur pilot in the USA.

Popularly known as ‘Boss’ Kettering his advice is the very best any dreamship doodler or car engine converter can get. What he said to all his engineers was simple:- “Before you start on any project read everything you can about the subject. There is no sense in re-inventing the wheel”.

Because it has focused attention on car engine conversions this article is not

loaded with specific technical stuff about engines. Because that is being done superbly by Bill Abbott. The most earnest recommendation is made that you collect all Bill’s engine articles in Airsport, and file them together so that you have continuity. And keep them right by your elbow when you are thinking of the dream engine you would like to build. Nowhere in the technical literature is there a more comprehensive guide to what you essentially need to know.

Pending the next ‘Dreamship’ article, which will try to deal with some practical aspects of engine installation, three suggestions are made on the subject of automotive conversions. They are based on an impression currently crossing my mind that over the last few years I may have heard enough verbally extruded bull to put a handrail around Tasmania.

No matter what the blandishments of photographs or accompanying deathless prose, ruthlessly ignore any car engine conversion unaccompanied by properly authenticated power and torque curves, which also quote the applicable test conditions.

Without these curves nobody, repeat nobody, can even begin to think about propellers. In cars horsepower drives wheels. Aircraft are entirely different. They are driven by thrust horsepower from propellers. This is always a lot less than engine power. Even a well designed propeller will throw about 25 per cent of the engine horsepower down the gurgler. A poorly designed prop could well be a taxying problem.

There are only two questions to ask about any car engine conversion that really matter. Unless you get answers to both there is no point in asking about price.

One is “Where is the power curve?” as above. The other is “Where is the PROOF that more than one of that engine have done X hours operation without doing themselves an expensive mischief?” Not glowing articles in mag­azines. Not Wot Merv Sez. Not that you can’t resist the shape of the spinner in the photographs. The word is PROOF.

People may approach you and talk at some length about the super car engine conversion they are about to create. If these people haven’t got a piece of paper in their hands with some elementary figuring (notably on weight) and an understandable sketch of how they propose to convey power from the crankshaft to a propeller (to cater for thrust and gyroscopic loads) don’t just ruthlessly ignore them.

Just tell them that they are wasting your time, that of every listener who unwarily gets involved, and their own.



By Fred Lindsley

(This article is from SAAA's "Airsport" magazine July/August 1989 edition)

Traps For young builders

Fred Lindsley continues his series with some notes on engine installations

“Has the world’s pre-eminent maker of commercial aircraft turned its manufacturing operations over to the Three Stooges?”

Now who would write a thing like that? Where? When?

Just to open this “Dreamships” article on a note of up-to-date aviation reality, the quote is from the front page of that sober and prestigious daily newspaper the “Wall Street Journal”, issue of 11 April 1989. It then goes on to devote an impressive 64 column-inches, nearly half a page, to aircraft inspection defects originating at Boeing’s manufacturing plant in Seattle.

Not only Boeing’s problems either. The FAA seem to be slightly thoughtful too. They after all, and like our CAA, have the exclusive final grasp of the permissive rubber stamp. The newspaper account could make amateur aircraft builders a bit thoughtful too, because it involves brand new multi-million dollar airliners in worldwide service.

The article, in brief, refers to a deterioration in inspection standards and more recently aggravated by 94 reported defects, from a variety of causes, affecting Boeing 757 fire warning systems. A few extracts from the article should suffice to outline its relevance to amateur aircraft building.

An overseas airline, which has been in business nearly as long as Boeing, in a letter to that company said that Boeing workers “are, in general, inadequately trained, possess a low level of working skills and, of paramount concern, seem oblivious that they are building aircraft where any mistake not properly corrected, or hidden, represents a direct compromise with safety”. That airline seems to hit the essential alarm button with two words: “aircraft” and “safety”.

The Executive Vice-president of Boeing’s Commercial Division says, “We would all like to do things with 20-year veterans

An experienced Boeing line inspector said, “unfortunately, Boeing employees get most of their information from TV”, which just may be of some significance.

We can have some confidence that Boeing will overcome their current problems, as is deserved by one of the great and pioneering innovators whose history goes back to 1916. Perhaps by more closely adhering to the established aviation methods and inspection procedures on which their fame was founded. It cannot be too strongly emphasised that, by civil aviation safety standards, there is no inherent difference between the largest airliner and your amateur built aircraft.

VW Conversions: Ancient History

The previous “Daylight on Dreamships” article stated that car engine conversions have a long and, with one no­table exception, a not particularly inspiring history. The exception, of course, is the Volkswagen engine or, more correctly, engines as various swept volumes apply. (It would be a bit depressing if some purveyors of horseless carriages really thought I had overlooked the VW).

VW engines have been powering aircraft for 46 years, a record that compares more than favourably with engines specifically designed for aircraft. Moreover the VW pedigree goes even further back into aviation history.

Ferdinand Porsche designed his first aero-engine, Daimler Motorgesellschaft in his native Austria , as early as 1908. It was a six cylinder airship engine of 100 hp. In 1910 he introduced a 65 hp four cylinder engine designed for an aeroplane, the Etrich III Seagull. In 1912 this was followed by his first four cylinder air-cooled “boxer engine” (the standard VW configuration) for Austro-Daimler.

During World War I Porsche initiated various six cylinder liquid-cooled engines for Austrian landplanes and seaplanes, varying from 90 to 350 hp. Also the Austro-Daimler AD 12, a V-12 of 345 hp which in 1918, modified with four valves per cylinder, developed 400 hp.

After the end of that war he designed the Daimler F7502, a two cylinder opposed air-cooled engine of 22hp which was installed in Klemm L20, L21 and L25 monoplanes.

Subsequently Porsche, then resident in Germany with his own design consultant office, was engaged on various projects for the motor industry. These included complete vehicles because his talent was not confined to engines.

One of these projects, from 1933 onwards, was the car which was developed into the original VW (Peoples Car) four seat sedan.

In April 1939 the first VWs started rolling off the production line. But not for long. The outbreak of World War II in September of that year soon replaced the sedan on the line with the angular “Kubelwagen” (Bucket Car) the familiar German small military vehicle. Different versions of this type were produced for a wide range of duties, including amphibians.

A wartime aircraft project required research involving sustained flying for handling and stability purposes. The selected research aircraft was a pre-war tailless sailplane of 20 metres span: the Horten III. In 1938 one of these had reached an altitude of 13,000 feet in the national gliding competitions.

The required engine was produced by the Porsche design bureau as the Type 274. It was a standard 1131 cc 25 hp Kubelwagen engine, souped up to give 33 hp. Fitted with a two-bladed folding propeller, the Horten III flew with this engine in 1943; the first VW to get airborne with its own power.

Flight testing was satisfactory and so rapid was development in those days that the Horten 9 tailless fighter-bomber, of 16.75 metres span and with two Junkers 004 jet engines, was exceeding 500 mph in late 1944. It went into production as the Gotha Go229 and the first one was on ground tests when the Americans captured the factory in the early part of 1945.

VW conversions have been in continuous use almost ever since and have attained commercial production status in several countries including Australia . Seven different such conversions are quoted in AD/ENG/4, with impressively high overhaul lives, but the dual question arises: “who has actually installed these engines?” and “who has actually logged, without notified defect, any of those overhaul lives?”.

With an aero-engine history going back to 1908 it is not surprising that the Porsche organisation are now producing an engine competitive with its USA equivalent. However it is not an engine which, in power or price per kilogram, will align with the needs and aspirations of most amateur aircraft builders.


VW Conversions: Recent History

Or from Deutschland to Downunder. Here we have three flavours of VW aircraft conversions. There are those which come with bits of paper confirming what you can reasonably expect.

There are those which have pieces of paper but lack adequate guidance on whether flea-market hairdryers or bass trombones should be connected to the inlet and exhaust ports. Thirdly, those of obscure antecedents and installations varying from the acceptable to the questionable.

The above paragraph is intended to embrace all that are now called “VW derivatives” in Australia . A dreamship doesn’t have to be a CAO 101.28 aircraft. The number of VW engines in gyroplanes and some “ultralights” is not known (does anyone have any reliable statistics like you can get with a few million cars?) but is almost certainly a good deal more than the 59 in registered amateurbuilt aircraft at early 1988. The first of these aircraft with a VW engine took to the air in November 1958 so there is around 30 years of operational history in that group.

For the first 23 years there were apparently no anxiety-arousing phenomena. Or perhaps there was a certain reluctance to notify defects. Or, possibly, the builders who installed the engines were a bit more careful in the days when it appears Boeing was a bit more careful too.

In February 1981 the situation started to change. A crankshaft broke on a commercially supplied engine of USA origin. A cracked crankshaft occurred in July of that year. Investigation resulted in the issue of an AD (Airworthiness Directive) which caused a lot of trouble and considerable expense to people unfortunate enough to have that make of engine, identified as the Revmaster in the AD.

Worse was to come. By July 1987 no less than 16 major defects had been notified on VW engines. All in 101.28 aircraft. Four defects involved crankshafts but there were other tediously expensive nasties too. The upshot of this was the issue of a revised AD, AL 8/88 in August 1988, applicable to all non-type certificated VW derivative piston engines. It includes magnafluxing of the crankshaft plus the conrods and the conrod bolts. It applies to engines before installation in an aircraft or in an another aircraft. It seems not to apply to engines in service which sounds a bit strange because of the 16 notified defects 15 occurred in service. The sole exception involved an engine before it made its first flight, and that defect may actually have been caused by misapplied motocar mythology. Is this disturbing your dream? You don’t have to read it. In point of fact those who don’t read about reality maybe well on the way to incubating even more ADs, to their and our imminent discomforture and/or financial loss. Because assessment of those 16 defects reveal some data which has implications extending beyond VW conversions. Of the 16 defects only four were accompanied by identifiable engine hours, the essential basis on which the authorities can decide which action may best serve our interests. 81 per cent of the defects affected the higher capacity VW engines. 50 per cent of them applied to (quote) “amateur VW” engines.

None of the defects involved the Australian commercially built conversion. From a 23 year happy hour period VW defects developed at a rate which nearly plots as a straight line upwards. Also the defects were associated with 27 per cent of the aircraft group. So, statistically, it’s not due to one builder having a hell of a lot of trouble with one engine; it means a fair number of builders. Were potential manufacturing defects to be eliminated there still remains a significant builder association factor.

Since the revised AD of last year there have been at least two further cases of crankshafts opting for metallurgical divorce. The writing may be on the wall for further ADs and this sort of thing could severely prejudice self administration in its initial testing period.

So what has caused the apparent change after 23 healthy years? Is there some hitherto unknown technical disease, a sort of aeronautical AIDS (Could it be Aircraft Inspection Deficiency Syndrome?) which is casting its evil blight on Boeing and our more modest enterprises? Have our lords and masters in Canberra, with their normal lively apprehension about safety, sadly failed to communicate to 101.18 aircraft, with registrations and C of As, the secret of the great good fortune and freedom from defects (and ADs) enjoyed by a probably greater number of VW derivatives in other aircraft with a provably poorer safety record?

There is something else that needs to be said about VW conversions. Those engines which have bits of paper tell you how much power you can expect to get at what RPM if you do all the right things on the installation. In this respect they are similar to certificated aero-engines. Who has taken their amateur assembled VW conversion to the local speed shop for a dynamometer check? Or ground run their engines with a suitably calibrated test fan? (Test clubs are probably something tried out at USA golf clubs). Who has ever bequeathed such wisdom to the columns of “Airsport”?

Because we are dealing with aircraft it is no good looking at VW car power curves and thinking they show the same power you can expect from your conversion. For one thing conversions usually have different camshafts but there are other significant differences too.

Power is the name of the game with aero-engines. You need every bit of it to get off the ground. On the climb every extra HP gives you a bigger percentage increase in rate of climb than that HP’s percentage of maximum power.

Not the possibility but the probability with VW conversions is that there are builders who believed some verbal say so on the power they expected to get, have further reduced potential power with weird induction systems and peculiar carburettors, and have not made the slightest attempt to ascertain what power they are actually getting, Doubtless their aircraft fly beaut (for the time being) but their outlook, from an engineering view­point, may verge on the juvenile.

Another HORSCOT report could harm a growing lad.

Powerplant installations

Aircraft are self-contained entities, Everything in one package. The modern airliner has control and fuel systems, hydraulic, pneumatic and electrical systems, an enormous array of avionics and instrumentation, emergency oxygen and fire protection equipment, galley and toilet installations, and an air conditioning system able to cope with +50 C solar radiation to -50 C, where the unbreathable air is so thin that the stalling speed begins to edge up towards the best speed that can be coaxed out of the power plants.

This sort of package deal tends to promote in LAMEs, not to mention aircrews, a respectful awareness about unity of function. And so it should be with your dreamship. The “firewall forward” outlook can put blinkers on a wider and better view. Powerplants comprise everything that distinguishes that dreamship from a glider. This may include the markings for the ignition switch or insect-proof vents on fuel tanks.

Perhaps the major difference between engine installations in aircraft and cars is that the aircraft background has a fair number of “do nots”. These usually translate as “sure, you’ve been doing that all your life, but don’t do it here”.

Probably the best place to start with dreamship engine installations is to familiarise yourself with what might come as unanticipated limitations to your freedom of thought. CAO 101.28 is a good start, and has some useful advice about airframes as well as powerplants.

Reading (and I mean reading) any CAO gives perspective. You may find that familiarity with them can operate to your future advantage. It will generally be found that those who moan about the obstructionism of CAOs have usually failed to read them thoroughly. The noises you hear from these people are frequently the licking of self-inflicted financial wounds. What may seem an ankle-breaking obstacle race laid on the ground, if repositioned at a high angle of attack, could well prove to actually be a cliff-scaling ladder. Another very useful leaflet is the “Guide to D of A Requirements Concerning Construction of Amateur Built Aircraft” originally produced in the old DOT days, as a 20 page duplicated document without numbered identification. A few aspects of it, today, might merit a little caution with interpretation but, for the beginner, it is a goldmine of practical guidance in one package.

Many intending car engine converters seem to conjure up an instant vision of themselves gazing at something bolted to the faceplate of a lathe, with calipers poised at the ready, while a steady flow of swarf curls up from that thing in the toolpost. Fair enough if there is a proper drawing for the part being made. If there isn’t a drawing your dream image isn’t on the right track. You may not be aware of it yet, but you are headed down an increasingly bumpy track because you failed to read the signpost. Which reads “Go-cart Engineering”.

Every bright idea you get about your engine conversion, if not covered by an acceptable drawing, is a modification by definition [either major or minor] and you might be surprised how often what you may think is just a minor mod is actually major, particularly on airframes. Modifications come under CAO 100.6. If future defects are associated with unapproved modifications you can be fairly confident about three things:-1. An isolated case will earn the perpetrator some chastening words from the authorities. 2. A few more cases will unleash some annoying paperwork or restrictions. 3. A few more cases than 2 above could see self-administration on a reciprocal course towards Canberra, and it might take years to get it airborne again.

And yes, converting your ignition system to screened harness, if not covered by any existing approval in black and white for your aeroplane, is subject to modification action on our 101.28 amateur built aircraft. So you never had to do that on your car? So just read CAO 101.28, the bit about educational purposes. Dreaming dies at the reality of every tomorrow.

The following parts outline some incidental notes on the usual sections appertaining to powerplants. Their essential purpose is to persuade people into reading more about these aspects, as it would be difficult to adequately cover even one of them with a complete article.

Engine Mounts.

These are primary structure, usually of steel tube. They are subject to all the varied loading conditions of the design requirements chosen, FAR 23 probably being the most accessible guide for most readers. Where some tricycle landing gears are involved the nose gear reactions may be part of the engine mount deal, and the gear sideloads may be a problem.

You also have to consider the heavy landing condition where the engine mass is hell-bent on going downwards with some G while the nosegear is inexorably being pushed upwards. All in milliseconds too. Its real fun thing if you can get it on video. Incidentally, and very recently, a Delta 727, while being towed from the terminal to the hangar, had one of the main gears collapse. Not a real fun thing and suggests that being careful with dreamships might be a good idea.

It is wise to allow for the eventual installation of a more powerful engine. And not just on the engine mount either. One of the very early Piper Cub models was power limited because some front fuselage tubes were not up to the numbers.

A problem of recent origin is currently causing some serious head-scratching overseas (and is related to an approved type too). Heat conduction through the engine mount bolts into a composite fuselage. The proposed fixes, not yet resolved as far as is known, include among other schemes large chunks of thick marine ply. Forward of the firewall forsooth. Maybe our dreamship could still getaway with the original Moth, Avian and Miles Hawk mounts where the engines were perched on forward extensions of the wooden fuselages.

Eyeballing engine mounts in cheap (?) tubing mock-ups, to check what you will hope to do with the real thing, is an overrated overseas pastime. It sounds clever and smart, and they cut and fiddle and re-weld when they discover that withdrawal or access to some component requires a rethink of the original brilliant and simple concept. Eventually they make the finalised engine mount out of 4130 and rejoice with a can of Milwaukee beer. Then they get to where they should have started. They do a drawing (and doing acceptable drawings of “as made” parts is exasperatingly tedious). For one reason, because they hope to sell some of the aircraft plans in Australia . For another thing because until they have a drawing, and some real dimensions and compound angles, nobody can properly stress the engine mount.

A secret can be revealed. Stressing is done on paper. It is not humping sand­bags. It is figuring out how many sandbags and where. Try to avoid getting sand in your eyeball.

Induction and Exhaust Systems.

With certificated engines these systems present few problems. The engine manufacturers are jealously possessive of their induction layout and carburettor installation, and resent people tampering with their ideas. When these engines go into certificated aircraft the FAA or an equivalent body ensure that any carburettor or cabin heater installation, which is associated with the exhaust system, is satisfactory. This aspect is of direct relevance to all sport aircraft, regardless of engine certification status. Cobbled up heater boxes, both in configuration and mechanical design, can cause power losses significantly greater than that due to heating of the intake air. This can also apply to the normal cold air mode. Sharp elbows, clumsy flaps and one-sided air­flow into the carburettor can all add up to a quite severe loss of engine breathing capability, volumetric efficiency, and it’s bound-to-clear-the-trees power.

That an installation passes the requirements for carburettor heating does NOT prove that the engine is satisfactory. While the normal loss of power due to increase of carb intake temperature can be calculated, it is essential to first have some data on the engine’s REAL power. Not what you believe, or wot Merv sez it is (plus the qualification that the landing gear has not been extended to suit installation of a RAAF Wapiti propeller, with power absorbtion characteristics unsuited to your engine).

There is much more to exhaust systems than giving them the sports car special treatment of cut, bend, weld and attach. Exhaust outlets if incorrectly located can give unacceptable carbon monoxide contamination with cabin aircraft. This has also occurred with open cockpits behind high powered engines, both military and civil. Would you believe that a Cessna 180 and a Fox Moth, satisfactory on climb and cruise CO tests, could produce CO contamination above the maximum on the glide with engines throttled back. Around 30 years ago but the extraordinary things airflow can do on aircraft hasn’t changed a bit.

Motor car designers, generally devoted to producing low drag coefficients for the parts readily seen, absent-mindedly embody a few square metres of extremely turbulent area underneath their vehicles. Some of this area can be eyeball measured (with a few exceptions like VWs) by looking down on the engine and figuring out how much of the highway can be seen.

This area is not entirely the result of technical amnesia. It assists cooling of the engine and, notably, a very warm exhaust manifold.

Not so in your dreamship. You make the cowlings real neat, with exhaust apertures just big enough for the engine to wobble in its mounting rubbers. You then contrive that a blast of cool Mangalore air at a rate of knots, varying with aircraft type but hopefully in excess of the sustained speeds you enjoy in your car, does some heat transfer equations on your exhaust system. If you are not very careful, or do not have a drawing of an approved exhaust system known to be satisfactory, your CAO 101.28 educational programme will embrace the study of differential expansions, loose studs, blown gaskets, burning at joints or elbows, and cracks which, if they occur at existing welds, it may be wiser and safer not to re-weld.


Fuel and Oil Systems

While both these systems imply an almost infinite variety of installations, it is best to start your thinking from basic principles. The fuel has to supply maximum power when you need it. Oil has to keep the engine going for a long time between overhauls (with routine oil changes of course). The fuel, to some extent, and all the oil also do an unseen but important job. They internally cool the engine.

Fuel tanks, except in quite small sizes, require internal anti-surge baffles. Tanks and their attachments to structure should, with full contents, meet the design requirement G loads in various directions. These loads, when run through the pocket calculator, can prove to be an awful lot more than visualised by builders intent on their own ideas about long-range tanks.

These loads can usually be checked by pressure testing tanks. Nominally 5 psi for oil tanks but a moveable feast for fuel tanks, depending on which design requirements you are working to. A cylindrical tank with its forward wall 15 inches in diameter, with 10 Imp. gallons of fuel (45 litres) and subject to the 9G forward emergency alighting condition, may just run into the FAR 23 requirement for a higher test pressure than the nominal 3.5 psi applicable to fuel tanks. Pressure testing of tanks applies to more than prototypes. It applies to the tanks each builder makes in case there is a teeny-weeny variation, including construction techniques.

Periodic tests in service are required since tanks can (and do!) deteriorate because of internal corrosion, or with some composites, the possibility of adverse characteristics developing.

Provision must be made for safety drainage of water for each fuel tank. They must also be vented in such a manner that no condition of flight can reduce fuel flow. Vent systems for wingtip tanks can be complicated, otherwise full tanks may start siphoning fuel overboard with as little as 3 degrees of heel. Fuel cocks must be positive in action, their management unambiguously placarded, and very definitely immune from telling lies or half-truths in the event of their operating mechanism being dismantled and reassembled. Fuel filters must be of adequate flow capacity, mounted at an accessible location to facilitate easy inspection and water drainage, and should be properly locked against vibration.

Fuel pumps are subject to the laws of pump engineering. If you have good delivery head, which for us is desirable, the pump may have pretty gutless suction head and its performance can be badly affected by long pipes with bends, elbows etc on the route from tank outlet to pump inlet. A problem of this nature recently occurred, the solution to which was dollar-devouring and delaying. Such problems with electric pumps can be clarified by prior bench testing to check what suction head they will lift against corresponding delivery heads and flows. No high tech equipment required except some plastic tubing, a tape measure, and a stopwatch. Don’t use that plastic hose in the aircraft. Fuel and oil lines, particularly forward of the firewall, must comply with the applicable requirements.

With few exceptions oil systems are supplied from the engine sump and, with certificated engines, no problems should exist if the engine manufacturer’s recommendations are observed. With uncertificated engines, and notably car conversions, a higher capacity oil pump may be desirable. Also, and particularly in the warmer parts of Australia which may be visited, oil coolers for additional or improved capacity may be required. On any “first time” engine these will be subject to modification action and, usually, reasonable flight testing before they get approved.

If any engine does require a separate tank, the tank must not be made from the higher strength aluminium alloys used on airframes. The temperature of hot oil can critically affect the strength and fatigue qualities of these alloys. With commercial aircraft it was customary to make oil tanks from the low strength almost pure aluminiums in the “0” or annealed state. These, after application of heat, revert to their original condition so what you’ve got is what you know you started with. In service they still need watching for cracks due to expansion or vibration.

Not too many years ago a very large USA car manufacturer spread gloom and despondency in the accounts offices. It was discovered that aluminium components in a new model became unacceptably weak after going through the body-painting booths where heat from infra­red lamps speeded things up. Oil tanks must have mandatory airspace volume, to allow for frothing, so they need dip-sticks. There is a big trap with oil dip-sticks in aircraft which has caused some serious accidents as well as much avoidable expense. The engine usually requires two different dipsticks depending on whether it is installed in a trigear aircraft or a taildragger.

Different part numbers is the normal commercial practice. So what is of little consequence on your car could be disastrous on your dreamship, which is a not very encouraging way to learn that aircraft truly are different.

Introducing the Fuel to the Air

This part is, in effect ancillary to the fuel system part. As we haven’t yet seen very many injectors around on our aircraft it can be assumed, for practical installation purposes, that the fuel system finishes up at the carburettor.

From that point on, with certificated engines, all you have to do is stick with the maker’s book of words. If you are not a LAME, and have smart ideas about “adjusting” the carburettor or using a fuel for which no approval exists, you deserve everything you may get [including premature overhaul bills] or not get from an insurance company, as some enthusiasts with a vintage aircraft expensively experienced a while back. Sealed and witnessed fuel samples failed to amuse the insurance company’s computer. The aircraft also had an unapproved mod too, which invalidated the C of A and ditto the insurance, so that didn’t give these enthusiast any comfort either. They would have been a tidy sum better off if they had, laughing with the customary ritual scorn, read some CAOs.

With uncertificated engines, which in this context largely means car engine conversions, some prudent thought might be applied. Those who have attained a notional diploma in practical aircraft engineering by attendance at Boshkosh university are, luckily, already loaded to maximum weight with erudition. They need read no further while we cast an eye on a VW engine function.

On the VW engine the carburettors are mounted on the top. They are attached to an induction system which was not a flash of inspiration by some bright apprentice, instantly promoted to Production Manager, but by experienced automotive engineers supported by extensive testing to ensure that under all conditions mixture would be equally distributed to the four cylinders.

The high carburettor is a nuisance on aircraft engine conversions, not least because it commits the cardinal sin of interfering with the neat cowling line. Other factors are the desire for a less obtrusive air filter and provision for adjacent intake air heating to meet those beastly aviation requirements. So the carb gets relocated, usually below the crankcase. This means a longer and more tortuous induction system between the carburettor and the inlet valves. Sometimes long enough to maybe re-freeze the mixture which the hot air intake to the carb was trying to cope with, since what comes out of a carb is inclined to be cooler than what went in. I’ve seen sharp elbows on cobbled up VW induction systems (not on legally flyable aircraft!) which could prove to be losing up to 10 hp where it is needed, if anybody got around to testing engines the way car and aircraft engines are tested. With these “Gee, don’t it sound beaut” induction systems is the engine’s volumetric efficiency better or worse? Is the mixture distribution correct for all cylinders? Do crankshafts welcome uneven power impulses? (Not to mention propellers).

See the earlier “Dreamships” article about strength of materials. Crankshafts behave like rubber bands and crankcases, particularly if they have been machined to accommodate bigger cylinder bores, like jelly.

The requirements for sustained high power, economical cruise which doesn’t cook the machinery, and an idle on the approach which doesn’t permanently bleach knuckles ensure that aircraft carburation is somewhat different to that applying to family or racing cars. The further effect of altitude and carburettor heating accentuate the differences.

The proper understanding of carburation, as distinct from making adjustments and changing jet sizes, does require some comprehension of the physical principles, chemistry, and mathematics wrapped up in these superficially simple devices. It is improbable that any “standard” carburettor for a car will, in an aircraft conversion of the same engine, give an acceptable defect-free overhaul life.

One of our more thoughtful Sunshiners did some interesting research on a VW conversion with one of those alleged carburettors which are a cross between a scent spray and the funnel on a model boat. He did it properly, with repetitive measurements suitably recorded and an exhaust gas analyser.

At wide open throttle he found that a 400 RPM drop in revs accompanied by serious weakening of the mixture could be produced without adjusting anything except the back end of his gravity fed KR-2. From the level flight postion, on a trestle, to tailwheel on the ground, a fairly modest angle of climb.

Such was the result from the change of a remarkably few inches in gravity head of fuel. The builder got my Noble Engineer Prize, largely because he very decently admitted that what he had inadvertently assumed to be my long-sustained polite scorn was, in reality, the benevolent protection of his bank balance and his physical well-being. What is more he wrote about his research, in the May! June 1987 “Airsport”. Yet there are still people talking about those wonderful pose-a-hell-of a-problem carburettors which makers of aircraft and car engines have never queued up to buy, and which underwriters may classify as a bit of a fire hazard.

As just a small part of any conversion project, carburettors and induction systems require some serious initial engineering thought. In the final analysis satisfactory and long-service operation depends on properly recorded testing, for a lengthy period under all conditions of service.

Not Entirely Wrapped

This doesn’t completely wrap up powerplant installations on dreamships, which in the next article will conclude with notes on equipment like instrumentation, ignition, engine controls, cooling, cowlings and propellers.

It is difficult to get entirely rapt about accelerating automotive engines 600 times on a properly cooled test bed.

This is not terribly different to what Gipsy engines were expected to do in the late 1920s, taking off and in baulked landings, before they got to a fraction of their very modest overhaul life.

So what is this big automotive test deal more than half a century later? Two possible answers occur to mind. One is that the horseless carriage honchos have only recently discovered this slam, bang, thank you Ma’am technique. The other is that they have failed to learn what they now need to know despite more than half a century of motor racing on sharp-cornered circuits. In this context what cuts the ice (or evaporates it) is how the aero-engine cools itself over the duration of operational time. Also bearing in mind that never exceed speed [Vne] exists to discourage, among other things, propellers from overspeeding.

The motor car is designed to operate over an infinite speed ratio, from zero to maximun. The morning traffic jam is part of the spectrum. To match the characteristics of normal internal combustion engines the car usually has a gearbox with a lot of cogwheels, with selected gear ratios conforming with textbook mathematical progressions. So throttle spindles (or injector systems) are subject to fairly continuous commotion.

Not so the aeroplane in the air. It has a pitifully small speed ratio (from stall to max) and gets by without a multi-speed gearbox to the propeller. So the aero-engine seldom subjects the throttle mechanism to almost constant movement. The result was that aero-engine designers laughed all the way to their kitchen scales, because they could make their engines lighter in weight.

The fact is that light-plane makers have always been looking for cheap engines. How many countries over how many years have produced motor cars?

How many aero-engine conversions have attained measurable sales on an accept­able international level? With the exception of the VW (which is invariably re­engineered in any respectable conversion) I suspect the car cult converters are faced with some historical research to answer the second question. Ironically it was Henry Ford who said “History is bunk”.

My thanks to all who have written and said kind words about the previous article on car engine conversions; a congratulatory letter from an automotive engineer with a prominent car maker was most encouraging. We can be confident that readers of “Airsport” include a number of people with the right appreciation for solving any technical problems and the perception to see that the problems are, in some measure, also ethical. Dreamship enthusiasts have been the bedrock of amateur aircraft building since the Wright brothers. Today the preponderance of visual entertainment, or information four second TV grabs, makes the beginner dreamship enthusiast particularly vulnerable to the influence of talking heads.

Such advice, if not confirmed by reading, may not always be well-founded. Bernard Baruch, many years ago, said “Everyone is entitled to their own opinion. They do not have a right to be misinformed”.

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