No Strings Attached
January 1962 American Modeler Article

Of course, we broke in many engines for hours on end. In the air they over-heated and died. One of them had so much compression it wind-milled in fast glides.

The truth of the matter is that some modern engines require no breaking in (and come to think of it, whoever heard of breaking in an Arden; we turned 12-inch and cut-down 14-inch props on a .19 on 90-degree days) and others will be ruined if not run-in. Have had Webra Diesels, for example, that would freeze if leaned out within four hours - but when they came-in they'd outlive a turtle. Two buddies have Super Tiger R/C's on the block for six hours and the engines are not yet ready to handle multi chores. Our Frog .09 diesels were still picking up rpm after 11 hours of flying! There was one glow .09 of ours that wore out the bearings before it broke in enough to fly! And so it goes.

Now that we have everyone suitably confused, let's listen to a man who knows what he is talking about (for a change!). So many club papers have picked up Hi Johnson's tips on breaking in engines that, on the theory where there is smoke there must be fire, we consider now the august pronouncements of one engine man. (If it turns out that engine makers, like modelers, also argue the issue, we no doubt will come back in due time to the break-in discussion.)

Having read Hi's very useful data umpty-ump times we have learned something new, proving that you can teach an old dawg new tricks. To boil it down, Hi describes a kind of molecular stampede in the metal as it is machined, worked, and treated during the manufacturing of an engine. (Incidentally, some guy on the side lines tells us that it is always "engine", and never "motor", because motors are electric).

Manufacturing processes, it appears, introduce stresses in the materials and the mischievous molecules remain partially unstable after that, no matter what. The crux of the matter is that the number of cycles of heating and cooling that an engine must pass through to attain molecular stability depends entirely on the molecular state of the metals at the time of engine purchase. Having had two new .15's freeze in the air, tossing expensive nylon props, and washers, into the weeds - new sleeves and pistons coming up! - we'd say this molecular state sometimes borders on anarchy.

Anyway, the word is that it's the first four or five minutes of running time (each time) that counts, and not a three- or four-hour break-in run that only frees the engine slightly. According to the Johnson Doctrine, many short runs, never leaning out, allowing the engine to heat up and cool off completely, bring law and order to the delinquent molecules.

The bigger the engine, the more the naughty molecules. And that is why Half-A engines take little or no break-in time. Shucks, we always thought the Half-A engine makers were more ingenious!

How about break-in fuel? Use a mild fuel (less than 12 per cent nitro) for the first hour or two - on .15's and up, decrees Mr. Johnson. For small engines, use the fuel marked "For Half-A" on the can. Adjust the needle to medium rich (medium rpm four-cycle), run off a five to seven-ounce tank. Repeat as many times as necessary for at least 30 minutes running time. To this we add, don't overload the engine with a big prop during break-in.

Is "Theory" Vindicated? Probably you, too, have noticed the growing respect for "long hair" designers. Like breaking in engines, the merits of theory as opposed to the rule-of-thumb school of design has always been good for a rainy day argument. For many years the American approach leaned toward rule-of-thumb. A lot can be said for it. In the beginning, pioneers endlessly ground out models, gradually changing this and that until they knew all the basic answers on proportions, areas, dihedral, and so on. Some became authorities - justly we think - by evolving formulas to express what they already knew, so that others could apply the hard-won knowledge.

In the middle years, when modeling attained truly popular acceptance, anybody who built a few jobs that flew fairly well could consider himself a theoretician. To the rest of us some of these talkative chaps were a pain in the neck. By reaction we became a bunch of rule-of-thumbers. Oh, there were guys who thought, witness Goldberg and the pylon gassie, but this was still a common-sense, though impressively reasoned approach. That is, it didn't require wind tunnels, slide rules, or adding machines.

Perhaps we began to have nagging doubts about our instinctive disapproval of "theory" when, in Europe men like Czepa, Hacklinger, Benedek, Van Hattum, Lindner, Samaan, largely through Nordics, displayed results that at least proved a man could be deeply theoretical and a top flier at the same time. So effective was their approach that until Gerry Ritz came along the U.S. had practically conceded it could never match the Continentals in some areas.

A rule-of-thumber himself, ole Zeke, has got to concede the theory boys - the authentic ones, not just every guy who decides to go into the theory business for himself - must really have an edge. This superiority is hard to evaluate because natural things - such as thermals and time limits - don't exactly encourage, or maybe even justify, all-out theory. But what has set us to thinking, is this achievement of Hacklinger's, a 44-minute flight in indoors.

Don't spoil it by telling us the flying site was super, but it seems to us that when a deep thinker like Hacklinger, who long has held wide respect, on relatively short notice (indoor is practically new in Europe) comes up with a performance like this, he has demonstrated that "model engineering" is equated with efficiency.

Though all designs that can max interminably seem the same, we shall suspect from here on in, that one must always be better than all the others. It is nice to have the best. Back to the drawing board!

Posted June 8, 2013