ZLIN 526 Trener Master
When Monoplanes Came to Stay
Text and Photos by Budd Davisson, Air Progress, November 1969
It’s interesting to go back and read what I wrote from this historical (and hysterical) perspective. This was written in 1969, the same month Woodstock took place. We were all very much children of the ‘60’s and I had yet to own, or even fly, a Pitts. The Zlin was my very first serious aerobatic bird and, after spending so much time in Citabrias, I thought I had died and gone to heaven. A year or so ago, I got to fly a 526 again and realized I shouldn’t have. You should never go back and look up that killer looking girl from your high school class. You’ll always be disappointed.
Incidentally, I apologize for the photographs. When this was written, I had been doing magazine work for barely a year and didn't have my photographic chops well tuned yet. Plus, in those days, when they converted a slide (these were all color) to black and white, it really sucked.
Shortly after the Wright Brothers proved they really were right, some smart aviation writer probably cornered them and wrote the first of a new literary genre-the pilot report. He more than likely bugged them for weeks trying to get them to take a trip to the Bahamas, so he could photograph it. Since that time, literally thousands of pireps have been pumped through the Royal portablepoet machines (Ed Note: Wow, this is an old one!). So many have been done that when a really exceptional experience comes along, it's difficult to find words that don't seem trite, adjectives that aren't overused. I've just had one of those exceptional experiences, and I'm not sure there are enough words left to do it justice. I have just flown a Zlin.
It started when I answered the phone and heard A.P.'s associate editor, Don Typond, grinning on the other end. "Budd, can you break loose this afternoon?"
Here you get some idea how narrow the gear is for the span.
The last time he asked 'me that, I ended up with a frostbitten Nikon (among other things) from flying a doorless camera ship in zero-degree weather. Since then, I've made it a habit to hang up on him immediately. I weakened this particular morning and asked him what he had in mind. He answered, "I thought you might like to fly a Zlin."
A Zlin? Oh, a Zlin! That's like being asked to help judge the Playmate of the Year contest, which can't be done as a spectator, so I made it to the airport.
Unfortunately, Hollywood has made the Czech Moravian countryside better known for Boris Karloff and vampires than airplanes, but the Moravan Zlin is most definitely an airplane. It's such an airplane that it practically axe-murdered the competition when it first appeared in aerobatic competitions around 1965, and it's still doing it. Many of the pros consider the Zlin to be the finest aerobatic airplane in production today.
The present competition aerobatic rules place great emphasis on vertical maneuvers, mostly because they are hard to do in high-drag biplanes. The Zlin has about as much drag as a toothpick, so it usually mops up. Since it is designed to perform on low horsepower, the Zlin is easy to keep within the mandatory boxlike frame. I met the Zlin Trener Master and Phil Paul at the same time, which is only right. N3466 represents 20 percent of the total U.S. Zlin population, and the fact that there are any at all stands as a monument to Phil Paul. Phil owns and operates Aero Sport Aircraft Imports (P.O. Box 2060, Lancaster, California), a fun organization that imports not only the Zlin, but also the Fournier RF-4 (the sailplane that thinks it's a Volkswagen), and the superbly finished Blanik sailplanes.
It's not so hard for Phil to get the airplanes into the country, but he's trying to figure some way that good old Uncle Sam won't hit him with 30 percent import duty. Since there are no bilateral trade agreements with Iron Curtain countries, Phil is left to fend for himself. What the heck, if the government doesn't like us buying foreign airplanes, why don't they build something as good?
When one first catches sight of the Zlin, the senses are assaulted by a profusion of straight lines-not curves, but lines. Everything is straight and businesslike-no frills, no fiberglass. It's beautiful! At first, everything looks wrong when viewed through American eyes, but it's only minutes before all domestic designs begin to look wrong.
The Z-526 is a flying contradiction. The long, long angular wing should make for a sluggish roll rate. The little teeny, knock-kneed gear should make it a real ground-looper, and that swizzle-stick-sized prop should make it a joke. Once again, I found appearances can be deceiving.
The overall impression of the Zlin is that of a barely civilian trainer-its khakis show through. Since the Europeans don't judge airplanes by the upholstering material, the elves in the Moravian Airplane Factory didn't have to worry about making their airplane anything but functional. Consequently, the machine was designed like a military trainer in civvies.The military layout was obvious as soon as Phil Paul started the walkaround. Everything that comes off is held on with Dzus fasteners, making maintenance and inspection a breeze. A screwdriver is all that's needed to leave the Zlin standing there in its underwear.
The fins on the dome keep it from spinning with the propellor and it drives a hydraulic gizmo inside that acts as a governor. The six-cylinder inline engine has a really cool bark to it.
The local tire-kickers usually start conversation with one of two questions. Is it a Chipmunk, and what're the gizmos on the spinner? I skipped the first question, but my own opening remark was that the spinner looked like a bomb fusing device. In reality, the two-piece spinner with the fins around it is part of the best constant-speed propellers either side of the Iron Curtain.
If you press on the spinner, where it says "do not press" (I couldn't resist), you'll find it moves in and out a half inch or so. It also rotates, independent of the propeller, driven by the little vanes around its circumference. This rotation drives a hydraulic pump contained within the hub, and when the spinner dome is pushed fore and aft by dynamic air pressure (proportional to airspeed), it actuates a valve that bleeds hydraulic pressure to the prop blades, changing their pitch. While you're flying, you set your power with the throttle (there is no propeller control) and forget about it. Even at full power, straight down, the engine will only turn up to the preset 2500 rpm, but you'd be doing 9,000 mph, pronto. If you watch the spinner while you're flying, it looks pretty weird because it will stand still for a while, then back up or move ahead, but it's always moving in relation to the prop. The Avia propeller people came up with a better mouse trap on this one.
My first thought on opening the engine cowl was "So, that's where all the old Rangers went." The 160-hp Walter Minor 6-111 is an air-cooled, inverted, inline six, similar to the Ranger, but it owes more of its ancestry to the British Gypsy-Majors. At one time, before the war, the Gypsy was built under license by Walter, but since that time only the general configuration has remained the same. Actually, the Walter is a welcome change to anyone tired of looking at America's flying VW mills. The boiler room is quite uncluttered and conventional, except for the presence of two carburetors, one for right-side-up and one for wrong-side-up. This respiration system is responsible for the characteristic "Zlin cough" as the engine changes from one carb to the other. The Z-526 is also available with a 180-hp, fuel-injected version of this same engine, and sometime early in 1970 they will have a 200hp Lycoming I0-360.
It should be noted that the Walter horsepower rating is the European DIN, not American SAE,' so 160 hp is actually somewhat higher than 160 home-grown ponies.
The gear is so simple it looks like a vocational school shop project. The oleos are big and beefy and retract straight back, a la Bellanca, leaving part of the wheel extended to lessen the inevitable embarrassment of putting the airplane in the down position when the gear isn't. The gear gives the appearance of being fixed down, partially due to its rugged construction and narrow tread. It's mounted on an extension of the fuselage tubing truss, making the fuselage and wing center section nearly indestructible. The tubing work looks suspiciously as if a civil engineer had a hand in the design and it inspires unbounded confidence.
The stress-skinned aluminum wing employs a fat, fat section and a long, long span to get all the performance it can out of 160 hp. The wing skins are fairly thin, probably .020 to .025 inches, but the individual bays are quite close and the rivet pitch is almost as tight as machine stitching. The Czechs really know how to bend metal, because I found no dings, no cans, and all their rivets are dimpled and set, with no shaving. The metal work is better than 90 percent of that found on American production machines.
The tailwheel is really gigantic by American standards. It's steerable and unlocks after it exceeds approximately 30 degrees. Since the Zlin is basically intended for use by the European aero club off short sod fields, the tail gear is as tough as the main gear. Also, N3466 sported a glider tow hook, testimony that the Zlin is not just another pretty face-it can work for a living, too. I wonder how a glider pilot would feel seeing his tow plane doing slow rolls?
The Z-526 is mounted like any other thoroughbred, from the left. The canopy slides back on a combination canopy rail/dorsal fin and is lockable in any position. Since the plane is soloed from the back pit, the greenhouse must be slid all the way back, which is no problem unless it chooses to rain, like it did on us, which means the guy up front gets awfully wet while the guy in back climbs in. Once you've hoisted your fanny over the side, military style, the flight deck fits fine, like a competition sports car.
The cockpits very much reflect their military heritage with lots of guarded switches, etc. The 360 degree gyro is a real kick as you can do vertical rolls using it.
I guess an airplane is an airplane, regardless of the language, so the go-knobs and controls are pretty much where you'd expect them to be. Most of the controls, throttle, mixture, and pitch trim are on the left side of the cockpit, but the rudder trim and flap handle are on the right side, necessitating changing hands on the stick to get to them. To change flap settings in a hurry during flare-out would require either three hands or a trained gremlin.
I noticed the handbook calls the control stick the pole, and I can see why-it looks like an aluminum baseball bat sticking out of the floor. I understand the healthy looking knob on the end was added when one of the Czech team pilots lost his grip during an outside loop and nearly cut some daisies.
When you're sitting in the back seat, you can see a very large bungee stretched down to the bottom of the front seat and looking for all the world like a primitive ejection seat (a Martin-Baker slingshot?), but Phil assured me that it was nothing but the seat adjuster, which incidentally, is the hardest thing to operate in this airplane. On the floor, to the right of the seat, are two D rings, one to adjust the rudders and one to adjust the seat. The catch is that you have to have all your weight off the seat before you can pull the D ring, and I always waited until I was strapped in before I tried to adjust my seat when you're strapped in a Zlin, you're really strapped in with shoulder straps and crotch straps. You can't even move your butt, much less pick it up off the seat.
The panel layout is fairly orthodox except everything is written in metric units, and several of the dials use two needle systems. The tachometer, for instance, reads like a sensitive altimeter, with one long needle and a short fat one. Once you get used to it, you find it is a great way of presenting things.
The panel is dominated by a three-dimensional, 360-degree electric gyro, which I wanted to slip into my pocket. The turn needle and ball are both right on the face of the gyro, making it one of the slickest, most compact presentations I've seen. I understand the Czech pilots do their vertical rolls on instruments and this gyro is the reason why. Phil has talked about importing these gyros, should anybody be interested.
I really liked the way the electrical system is set up. It has two sets of masters. There is the usual master on the left side of the panel, but then each subsystem-the landing gear, the instruments, the starter, and so forth-has, its own switch. This bank of subsystems is on the right side and is protected by little guard rails to keep from tripping them with chute straps. So, actually you have to throw three switches to get the gear up: the master, the subsystem switch, and the gear switch. Redundant, but safe.
After Phil had strapped me in and pointed things out, he hopped up front and talked me through the start procedure, since there are no starter controls up front. After throwing the main master, the instrument switch must be thrown so that the instruments will be activated. The engine is usually primed several shots (the primer doesn't have a lock, by the way) and fuel pressure is brought up with the small plunger under the panel on the left side. It's next to the engine fire extinguisher, so I suggest looking carefully before pumping. Fuel pressure up, starter system switch on, mags, and hit the starter. It's a real shocker to hit a starter button and see the prop back up; I'd forgotten about the left-hand rotation. The engine catches in that throaty kind of coughing roar that comes from inline short stacks. It's not unlike a Merlin and is very pleasant.
At first, you feel
as blind as a nearsighted bat because the panel is quite close to your
schnoz, the nose covers the view ahead, and the wing is a bit forward, cutting
off some side vision. After a few seconds, though, I noticed that the narrow
fuselage blocks very little view, and the tailwheel was so positive it tracked
like a tricycle bird.
It's a good thing you don't need brakes much while taxiing, because they are a real bear to reach. I had to lift my feet clear off the floor to get my toes on the part of the pedal marked brakes. That's something worth remembering during landing.
Canopy pushed back,
S-turning slowly, gutty-sounding engine up front-I just knew I was going to
eat this up!
As we lined up on the middle of the runway, I flipped the landing gear system switch on. Phil suggested I take off tail-low to preclude the possibility of overcontrolling and chewing up the prop. When I fly a strange bird for the first time I'm all nerve end, and this time especially. I eased the power in and moved the stick up to a neutral position and let the airplane fly itself off, while I kept it moving straight. I was already off the ground before I realized I wasn't having to work very hard to keep it straight. I hadn't even noticed the fact that the prop was turning the wrong direction and torque/slipstream/gyro precession/P-factor was trying to turn me right. I think most pilots just keep the nose straight and don't really pay any attention to what they have to do to keep it there.
The gear came up with no noticeable pitch change and I set up climb at 120 kilometers per hour and 2400 rpm. This was my first problem with the gauges. The airspeed is marked in furlongs per decade or something, but it took no time at all before I felt completely at home in the metric system. Granted, I had no idea how fast I was going, but it made no difference because it's all relative. By using a rough conversion factor of six, I later deduced that my climb speed was about 75 mph and rate of climb was 1,100 fpm. How's that for 160 horsepower at all up gross of around 2,300 pounds?
As we climbed, I could feel the slipstream nibbling at the ailerons as I'd accidentally stick a little out. My first couple clearing turns, while climbing, were pretty brutal affairs, this bird demanded a much lighter hand than I was giving it. My intent was to investigate the general flying characteristics on the first hop and then go back up and do some aerobatics after I'd felt the plane out. Well, the best laid plans . . .!
We leveled out at 3,000 feet and I racked it around in a couple turns and proceeded to go out of my mind! The thing was fantastic! The aileron pressures were next to nothing, and it was so smooth, it was obscene. With the flick of a wrist, I spun the New Jersey horizon in a slow roll. Absolutely fantastic! Totally effortless! From that point on I just played it off the wall. At the end of an hour, I still had no idea how a Zlin flew, but I sure knew how it did aerobatics!
The Zlin was the first honest-to-Aresti aerobatic machine I'd ever tangled with. I'd wrestled my way through several hundred hours of akro time in Champion Citabrias and had originally planned on doing a comparison of the Citabria and the Zlin, but it would be ridiculous-like comparing Phyllis Diller and Raquel Welch just because they're both women. The Citabria is an airplane capable of doing aerobatics, but the Zlin is an acrobatic airplane. It's a whole different ball game.
The first hour up, Phil showed me how the Zlin did her stuff, and I noticed a rather unusual thing: Phil Paul flies better upside-down than right-side-up. He demo'd some outside push-ups and then showed me its famous vertical capabilities. He'd dive to around 300 kph (186 mph), make about a 4-G pull-up, and do an easy vertical roll and recover in inverted flight. Four-point verticals require a little more entry speed, but are just as effortless. I flopped around for a while trying them, but I would lose heading every time, and no points are given for a five-eighths, nearly vertical roll. I never did get it down, and it's not the kind of thing you can practice in a Cherokee.
I messed around with the snap rolls and found it snaps much cleaner and faster if you use aileron, moving the stick back and then into the corner, in an L-shaped motion. Doing it this way you can start and stop anywhere you want. It really knocked me out to be able to do a razor-sharp one and a half snap, drop the nose, and do an outside loop from the bottom.
Citabria pilots aren't exactly known for their featherlike touch, so the first time I slow-rolled the Zlin, I nearly tore the stick out of the socket. The stick forces are light, and the wings act as if they are wired directly to the stick. Use a little stick and it rolls slow; use a lot of stick and it rolls fast, and one is just as easy as the next. Because of that backwards-turning prop, it rolls a little easier to the right, or at least that's the direction I could hold my points better. It will roll out of level cruise, and holding the nose about 10 degrees high gives enough room to do roll after roll. Needless to say, I spent most of my time going round and round. Boy, is it fun!
I didn't even notice the torque pulling the wrong direction until I started trying hammerheads. I'd pull her up, kick rudder and nothing would happen, we'd stall and whip down. I'll bet I did that a dozen times before it dawned on me what was happening. I tried one to the right and it pivoted as if it had a nail through the wing tip.
I'm so used to clubbing an airplane to death while inverted, that my first attempts at inverted flight resembled outside loops. The Zlin flies so smoothly and so flat while inverted that I could trim it up (down) and fly almost hands off. I was pulling 180-degree turns at 30-degree bank and still climbing about 200 feet.
The zero-G stall speed must be significantly less than the 1-G stall because I was coming over the top, outside, with barely any airspeed showing and still under perfect control. While pushing it outside, I would put in just enough forward pressure that the minus-3-G warning light on the panel would light up, then I'd ease off a bit. This way I could easily control the negative loading. I can't visualize needing much more than 3 Gs negative because of the way it will pull itself around outside.
The question always pops up, "How does it stack up against the competition?" The competition is the venerable Bucker Jungmeister and the peppy little Pitts. The supermodified Chipmunks of Art Scholl and Harold Krier also figure, but that type is not nearly as numerous as the other two. I can only say, in comparing the Zlin and the Jungmeister, the only other one I've flown, that each machine has some qualities that make it better at specific things than the other one, but they are both a lot better airplane than I am pilot. The Bucker snaps like crazy and is more responsive on the controls, but the Zlin doesn't know up from down and has practically no drag to slow it down when the nose is pointed up. I think when a machine gets up to the Zlin/Pitts/Jungmeister class, it takes an awfully picky pilot to say one is better than the next. It depends on what you want to do, and I think I'd like to have one of each.(Ed Note: 30 years and 4,000 hours of Pitts time later, I’d say I was full of sh*t on this one. The Pitts Rules.)
I had flown the Zlin for several hours before I got around to investigating all that dull stuff, such as stalls. In all configurations and positions, the stall comes with a predictable shudder and a sharpish mush, usually rolling slightly left. Because the bird is so clean, the second the nose is dropped and power applied, it's back flying again. I stalled it inverted several times and it snapped back right-side-up and tried to continue into a normal spin, but it was easily stopped.
Although the controls are light, it takes a fair amount of stick movement to effect a large amount of change. In this way you're able to control all your movements much better, with no tendency toward choppy appearing maneuvers. The Zlin is responsive without being twitchy.
The landing was the biggest surprise of all. With that narrow gear, I expected it to be like landing with my feet in a bucket. We flew the pattern at about 75 mph, dropping the gear as we entered downwind. In addition to the gear position indicators on the panel, a candy-striped pole about six inches long comes up out of each wing panel, when the gear comes down.
With all that wing, the Zlin will really reach out and glide, so most approaches were made with full flaps. The flaps are split trailing edge affairs that help slow the slinky thing down. I had a little trouble finding the ground the first time around, but after that it was just a matter of gently (I repeat, gently) rotating into the three-point attitude and holding it off. Because visibility does tend to disappear rather rapidly, I found my eyes clicking back and forth over the canopy rails like a dime store window display.
As soon as that big
hairy tailwheel is on the ground, you're practically home free. The rudder is
effective down to zero airspeed and the wing is so close to the ground that
the wind has trouble getting under it in a crosswind. Phil turned me loose
landings, all of them crosswind, and I'm sure no Smiling Jack Knight. Forget about the brakes on landing roll-out, they are just too blessed hard to get at. The airplane slows plenty fast by itself.
There is something
intrinsically groovy (Ed Note: I CANNOT BELIEVE I SAID THAT IN PRINT!!!
I THINK I’M GOING TO HURL!) about sliding the canopy back, and feeling
the sudden breeze on your head and neck. I S'd back to the ramp, inhaling the
sounds and feeling as if I'd just written my name across the sky in giant letters-I
really had a blast!
At a hardly bargain basement price of $21,600, I don't expect to see a Z-526 Trener Master in every garage, which is a shame. Remember, almost a third of that price is import duty, so we can blame Uncle Sam for not letting us have neat foreign playthings.
The Trener Master has several distinct things in its favor. It can do all Aresti maneuvers with two people aboard. With a cruising speed upwards of 125 mph, and auxiliary tip tanks, it is a cross-country machine comparable with the 172 class. A little noisier perhaps, but lots more fun. Since it is licensed in the United States only in the experimental category, it can't be used in commercial operation, but Phil Paul expects it to get U.S. certification within a year. With certification, you could teach aerobatics with the same airplane you tow gliders, or take the wife to the seashore (if she wears earplugs). The airplane comes with loads of spares, but the maintenance problem will disappear next year with the first Lycoming-powered ones.
I knew when I was
done I'd be dissatisfied with what I had written. There is just no way to convey
the feeling of total freedom this airplane gives you. About the best I can say
is corner Phil Paul, and get a ride. The airplane will sell itself.
The ZLIN Z-526 TRENER MASTER
Takeoff distance ................. 820 ft
Initial rate of climb .............866 fpm
Service ceiling ............... 15,580 ft
Maximum speed ............... 151 mph
Cruise speed 131 mph
Cruising range (with tip tanks) .... 608 mi
Stall speed (flaps & gear down) ... 53 mph
Stall speed (flaps & gear up) ..... 61 mph
Landing distance .......... 508 ft
Engine . Walter Minor 6-III
DIN rated horsepower .............. 160 Rated speed ... 2500 rpm Propeller ...... Avia V-503, fully automatic
Wing span .................. 34 ft 9 in
Wing area ................. 166 sq ft
Length ............. 25 ft 8 in
Height ........................ 6 ft 9 in
Wing loading ............... 12 Ibs/sq ft
Empty weight 1,430 Ibs
Max weight, unlimited aerobatics . 2,000 Ibs
Max weight, normal operation ... 2,150 Ibs
Fuel capacity ................... 26 gal
Fuel capacity with optional tip tanks . 44 gal
Fuel consumption, normal cruise . . 91/2 gph
Basic price in United States $21,600
Photographs by Don Typond
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