BILL WINTER'S FOR OPENERS
For 10 days now we have been AWOL from the editorial desk, living a fantasy of years: to fly, just once, until we had our fill of flipping props, tweaking sticks, chasing thermals, and all the super jazz. We are stiff, burned, and have a crick in the back from tossing that malevolent Sniffer. Only the real-world reality of having this column next Monday has taken us out of the high of a lifetime. Vacations around Model Aviation are as common as thermals in a blizzard, so we have a guilty twinge every time we think of publisher Wheeley, to whom six-day weeks are routine, riding herd on our loose ends while guarding the stockade.
We had only 19 flights this year, a sad affair that called for stern measures. Such a situation can justify murder. Now we are covered with briar scratches. So is Flyline's Herb Clukey, another thwarted modeler, who suffered with us one of those nightmare searches, the penalty of the worst piloting error we've made since 1954.
The Sniffer and thrust-line mysteries
That horrendous piloting error. You will recall that, in the last issue, we had commented on John Preston's new safety column in this issue, and the multiple causes of an accident. The type of accident we normally think of is that which involves the safety of ourselves and others. But the great majority of accidents are those suffered by the airplane(s) itself. If a biz-jet stalls out, there is a final report which sounds as if it were written by the Nuremberg Trial judges. Such hearings add immeasurably to safety in the air; often there are fixes in aircraft types, or in the complex web of communications and procedures, in engines, etc. In contrast, a model crash triggers such thoughts as "Get the Hot Stuff," "Gawd, I hope the radio isn't busted," or "If I rush that kit in the basement I can be flying in a couple of weeks."
If you suffered through an earlier column about the thrust-line mysteries of our six-foot Sniffer, you will dig this. (For those who didn't, we had removed right thrust only to have the machine develop a vicious right turn on power after launching.) In the Sniffer, one would swear that torque rolls the ship to the right—one must anticipate the opposite of torque when the throttle is advanced. Now we don't know what real plane designers know about pylon effect, but we modelers know that with the prop wash on a high-wing (parasol) pylon job (with side area in the mount as opposed to open center-section struts on the real plane) there is a pronounced right-bank effect, far stronger than the left-bank force created by torque. This was the secret of Carl Goldberg's immortal "discovery" of the upward, right-hand spiral of the Zipper. However, nothing in this daffy business is an open-and-shut case; Bill Hannan warns us to put left thrust in the 9-foot Aristocrat cabin model because every Aristocrat he ever heard of, including Peanuts, demanded left thrust—and the cabin is not all that high in relation to the thrust line.
The Sniffer's normal flight on an OS 35 and a 4-ounce tank is about 12 to 15 minutes. This is because most of the flight is with a bit less than half power. When it encounters even light lift, that becomes 15 to 20 minutes. We have taken it out of lift after an hour. At a half or third throttle, the engine drones on for an eternity. In strong lift the motor run is unbelievable in idle. The ship will ROG handily straight ahead, but usually runways do not exist, and then it is hand-launched. Due to the right-turn tendency (now zero thrust, but with 4 degrees down thrust) it goes straight, provided you have set a fair amount of left mechanically at the clevis. (You could use left trim but might run out of it if needed later.) As the ship climbs, we gradually come back on the power a click at a time, feeding in down trim rather quickly. As propwash drops off, with lower power the ship wants to turn left, not right, and one trims rudder back to neutral at the transmitter, and then to a right turn once cruise is established.
It is a fairly heavy, robust ship, and will slowly climb in full down trim with throttle just back of midpoint. As it goes through lift and appears smaller to the eye, the power stick comes back, and back. (Low-power trim is cut off.) Power stick position is a rough indicator of how much the ship is ascending in lift—a sort of thermal sniffer. The engine may be idling and the ship a speck. It sure beats having to make a power-pod glider (tough to fly in wind) when an ordinary model does the job easier. You have almost 10 minutes to get established in lift before power ceases. If sink is encountered, advancing power one, maybe two, clicks regains altitude.
Thermaling technique and trim interactions
To compensate you have to feed in one, then two, clicks of right to retain the thermal-seeking circle. Add one click of power, and it is immediately necessary to add one click of left to avoid tightening the right circle. Two clicks of power and it is two to three clicks of left rudder. If you slow up the flight with a click or two of up trim, then it is one click of left because the up elevator also tightens the bank. Strong use of elevator on a 3-channel job close to the ground can turn your bank into a corkscrew and the only salvation is back power and opposite rudder. You may fly for 10, 15 or more minutes using nothing but slight trim adjustments, never moving a stick. This may extend from after launch to setting up the approach when the stick is finally needed.
You don't know when power dies, unless you have a keen ear. But the ship then comes out of its right circle, power off, and a good bit of right trim is then needed to continue silent right-turn circling.
All three of our airplanes do this. One is a 30-powered 5-foot sport cabin, the other a lightweight 19-powered low-wing 6-footer—so you can soar with many common sport models if you give them the chance. Slow flying is less effective in finding lift, and in staying in it when found, than setting up a wide circle at a relatively fast airspeed. Slow flight is known to increase sink and you can get many a floater of a real light plane into a short field by making it sink (notably the T-Craft and Piper Supercruiser—unflapped). In lift, the Sniffer speeds up and appears to be slightly nose-down. One supposes that in riding a rotating mass of air, the ship may have a "tailwind," and only looks faster.
The 1954 optical illusion and a 1979 lesson
Let's go back to 1954. Twice that year we were trapped into a Chinese approach by an optical illusion. We all know the danger when a ship is far out and a turn is made into a long, high approach, especially in late daylight when silhouettes play tricks. It is easy to turn the wrong way. So you are set up, coming in straight as a string. Suddenly, your gyro tumbles, your black box spews out hysterical gibberish. Sometimes the plane appears smaller (that can't be!), or it seems to have steepened its glide, almost to a dive—that happens as it nears the earth way out in the tullies. You swing it—everything seems backwards—into a right-way (left) turn. Far too late!
Now it is 1979—25 years later. Everybody knows about overhead approaches, etc., but we swung into a great circle around the downwind half of the field. What we planned was to line up the ship pointing right at us—aim at yourself and your track is perfect—intending to have the ship glide by just above our head and touch down behind us on the open two-thirds of the field. The Sniffer turns gently left onto the crosswind leg and we judge to a pinpoint when to turn left again, gently, onto final. Done. We wait. The ship suddenly—eventually—looks small, damned small! It had turned right instead of left!
If a ship is carrying improper rudder trim (right in this case), or has a slight warp, or anything that can cause a gradual right circle, there is a point on the crosswind leg where, say, 100 feet or so, is the radius of the 90-degree turn into final. If, in that distance, something causes it to fade right—even though you are alert—the eye cannot pick up the misadventure when the plane is a silhouette. It seems to turn as commanded and appears to be lined up. Not necessarily!
There is another interesting thing. Models are always farther away or higher up—by a considerable distance—than the pilot thinks. We established that the fatal turn into final was made at the equivalent of two short city blocks away, and when the Sniffer hit surprisingly distant power lines, it was some 2,200 feet from the spot. At 2,200 feet the ship was clearly seen as light struck its wings. But when we fly high up, or far out, an image can play tricks. In making a far wide turn, there is one point where you can't be positive—except by reasoning—precisely what the ship is doing and how much correction it may need. And you don't dare touch it. You have to ride it out until the platform is glimpsed. Question: If the Sniffer appeared sharply at 2,200 feet distance, how far, really, is it sometimes during ordinary flight? Walk off a few hundred feet from the flying site and watch other airplanes—or walk out to where they reach the end of climb-out. You are in for a shock.
Well, when the Sniffer hit the lines, the wing was seen clearly to fly off and whirl madly in the air. But when the ship was found after an hour and a half, it was in one piece, wing in place, high in trees behind the power lines—undamaged! It had been thrown like a frisbee into high trees by the power lines, which did in the sturdy leading edge in four places. But how could we have made such a stupid mistake? Any guesses? The on-the-spot analysis produced the damning evidence. The rudder-trim lever was still in full right! It is a golden rule to get all trims back to whatever you need for neutral by the time the approach is set up. But we forgot—just once—and the price had to be paid. Yes, we did make the final turn into the approach quite properly, but on relaxing the stick, the right trim gently reversed the turn. And another sucker was trapped. It is hard to live with a smashed or lost airplane, and airborne system, for such a seemingly trivial error. Don't say it! Pilot error.
There is a sure way to eliminate this problem. When power-off is entered, trim the rudder (3-channel) for a weak left turn (or right for a right-turn approach). When you enter that far-out turn into final, be sure it is positive—the left rudder trim prevents turn reversal, and as you close in, you may neutralize rudder. The Sniffer (ours) is a beefed-up sport job and cannot be stooged about to kill altitude once into an approach. That builds up speed and it will overshoot by 100–200 feet—unless you grease it on with forward stick. We are not that good.
Defining a trainer
Defining a trainer is as elusive as determining the priority of the chicken or the egg. If you will pardon editorial nepotism, our son, Mike (according to Walt Schroder's No. 1 Son scale, this would be No. 5 Son), finished his Bridi 40 Trainer—a Don Dewey design from RCM—and brought it 300 miles to the well-head for checkout. This is his first airplane of any description and he already handles that honkin' K&B 40 like an expert. We did say that Mike is gung-ho and wanted ailerons and aerobatics right off the bat. Oh, dear. But he is a career man, armament and stuff on F-111s and A-10s, so we gambled on his skills. He did better than his old man, although we forgot to tell him about air gaps at the control surfaces. No matter—we still could fly. It took three evenings for him to straighten out linkages and movements.
The one problem—how to get small nose-wheel steering along with proper rudder from an itty servo wheel, there being no room for an arm—was neatly solved thanks to some of those Du-Bro hardware items. These guys—as does Goldberg—have much ingenious stuff for anything you can possibly run into. Using a ball-link thing intended for an aileron servo which drives two pushrods for bellcrank actuation allowed us to get both the nose-wheel Ny-Rod and the rudder pushrod on the inner hole—on the same side—just perfect. The only structural change we had Mike make was to add a 1-inch-wide 1/4-sheet doubler to the cabin sides at the wing seat—there is nothing but 1/8-inch sheet siding between the main cabin bulkheads, and it stood to reason we would bang this crate around.
Bridi 40 checkout and engine troubles
Came the great Saturday morning and we invited that mad test pilot, Don Srull, to make the first hop. Joe Bridi shows two CG positions, one forward for beginners (!) and another for aerobatic hotshots. Now, let us say, this is a high-performance airplane and is ideal for preparing an already fairly experienced flier to step up to Pattern. For sport, it is hot as a Mexican pepper. As built, it was right on the money for balance. After some taxiing about, and a couple of straight high-speed taxis, the wood 10-6 spewed grass in all directions, Don got it off smoothly, and, praise the Lord, it was as true as a die, nice and flat, and finally barrelled narrowly in a very wide, shallow turn. But as the prop unloaded, the engine died. Was it dirt? What then? The needle was wide open, and ground tests nose-high were perfect. (What do beginners do?) Twice the engine problem persisted. Overnight we switched the 2½-inch wheels for 3¼-inch jobbies—that ended the long-grass problem.
The last we saw of Mike we had advised him to take advantage of the third hole in the Sullivan 8-ounce tank to run muffler pressure—Du-Bro has a bolt-in tap for the muffler if you don't wish to get into tapping. When we asked Bill Evans about this, he laughed and said Johnnie B says that engine runs merrily, if not best, without aids. Bob Harrah said the same thing. Joe Bridi said to take apart the Perry carb and check for dirt. Mike's brother, Rob, now inactive but a sharp pilot, just suggested to see if the vent tube was close to the tank wall, which would create negative pressure in the tank. Anyway, the 40 now is singing and Mike is commended to the hands of some New York hotshot. K&B has switched carbs on this 40, so we'll replace it to make sure. Incidentally, this one model of the 40 has sold 390,000 copies, breaking the K&B record of 310,000 for yesterday's Greenhead 19.
You have got to realize that the Bridi 40 is a "Basic" trainer. That requires an instructor pilot if you are a raw beginner—and that goes for every airplane of this type on the market. We prefer to call it an Advanced Trainer, the order being Primary, Basic, Advanced, and then the final step, whatever it may be. In modeling this is complicated by such factors as what equipment one sinks his money into, what kind of help he can get—so there is no hard and fast rule. (Heaven help the isolated greenhorns.) There is so much to be said on this subject, we'll have a go at it in next month's column.
In memoriam: John "Red" Hillegas
The ranks of the Old Guard slimmed painfully with the passing of John "Red" Hillegas, who was a respected friend of countless people, and a host of old-timers. He was a genuine contributor to this hobby and all it entails—being ever-helpful for one thing. With his wife, Irma, he operated a famous hobby shop on Cleveland's East Side for so many years that its closing in 1971 seemed to mark the end of an era. Where it all began, very few of us ever knew. Red was always there.
Actually, he opened the shop doors way back in 1926, the year before the Lindbergh flight to Paris, in the dark ages before American kids abruptly discovered the air age. Red's was the place to go if you needed some specialty item for a pending competition. He was a great vice-president for the AMA during the war years—a totally constructive man. He served on early AMA rules committees. Red and a couple of his pals, Dick Korda and Howie Robinson, would give away the pleasant hours in our room at the B.O.O. at some Nationals, and would razz the editor unmercifully. In his early days, Red was a railroad inspector. And we see by the clipping Irma (they were married 53 years) sends us that Red was a seventh-generation descendant of Michael Hillegas, first treasurer of the United States, who served under George Washington and the Continental Congress. In all respects, Red was as sound as yesterday's dollar. He died at 76 years of age from a heart attack. If we get to where we think he is, we hope he has a hobby shop.
Transcribed from original scans by AI. Minor OCR errors may remain.
