Zlin Meister
By David Brown
Proud Owner Jeff Koehler with Zlin N242DC in its present paint scheme. (David Brown)Twenty years ago former F-15 pilot and Air Force Academy graduate, Jeff Koehler, worked for Northrop Grumman on the B2 program, but still yearned to return to the skies. Initially he used a Cherokee 140 to commute to Los Angeles from his home in Camarillo, but eventually he realized that he wanted more from his flying. What he really hungered for was an aerobatic aircraft, so took his time looking at all the possible contenders, ranging from the Pitts Special to the CAP 10. One consideration was cockpit room, as Jeff is over six feet tall. This ruled out a number of contenders with cramped cockpits.
Working in Melbourne, Fla. by this time, Jeff had an opportunity to fly the Moravan Zlin 242, which was a Lycoming-powered variant of the Czech Zlin 241 of famed aerobatic lineage (Zlin 526 and Zlin 50) and was at that time relatively cheap for a new aircraft ($125,000). Also, the cockpit was of ample size.
Says Koehler, “I was immediately impressed by the Zlin. The controls used pushrods and ball bearings, so there was no slop. Control harmony was good between pitch and roll. It flew in a very precise manner, just like a jet. It was a rugged aircraft (+6/-3.5g) and had a Christen inverted oil system to keep the engine running through even advanced aerobatics”
This photo was taken when Jeff Koehler’s Zlin had a stopover in Arizona en route to the west coast. (Budd Davisson, airbum.com)Koehler was soon the proud owner of an aerobatic Zlin N242DC. Having bought the Zlin, the next step was for Koehler to ferry it back to the west coast. He says, “In addition to the two main tanks, the Zlin has two auxiliary tanks in the outer wings. Filling them all gave a four-hour range. The downside was that at this time, the Zlin had no navigational gear. I flew from Stuart airport flying strictly VFR and called in at Melbourne before fighting bad weather to the Florida Panhandle. Then I continued to Houston where I broke the journey to meet family. The next day we continued in improving weather to Scottsdale, Ariz., and finally in crystal clear weather, I flew the last leg to Los Angeles, cruising at 12,500 feet altitude and burning around 10 gallons per hour for this part of the trip.”
The Zlin was put to work as an aerobatic trainer and has served mainly in this role for the last few years. It can accomplish all the normal positive g maneuvers, can handle inverted maneuvers, and will spin nicely.
Koehler said, “We have had students complete our aerobatics course and come back with big grins plastered across their faces. In addition to the superb handling in maneuvering flight, they like the big canopy with exceptional visibility. We have even had one student start flying our Zlin without any experience and go on to qualify for his PPL. From my point of view as an instructor, I like the side-by side seating, with substantial seats, which can be configured for touring or take parachutes for our aerobatic flying, the military-style cockpit, which has hefty levers and switches, and the corrosion-proofing of the structure, which pays dividends in our operations close to the Pacific.”
Jeff Koehler has worked extensively with the local “Tomorrow’s Aeronautical Museum” in Compton, demonstrating the aerobatic capability of the Zlin to under-privileged kids. “It’s rewarding and always neat to demonstrate zero g to them, when they will experience the sensations of zero gravity, although securely strapped in.”
The city of Torrance is also a stopover for European airline crews, and Koehler has given a range of airline pilots an introduction to aerobatics, “which is much appreciated as a welcome change from hours of straight and level flying in their day jobs.”
Over the years, this Zlin has been upgraded with Goodrich electric gyros, so it is now IFR-capable. Jeff has swapped out the original wheels and brakes for Cleveland units to improve access and ease servicing. The original single battery was prone to leak acid when inverted and has been replaced by a pair of US 12 volt batteries. It now has Goodrich electric gyros, King radios, and has been used for serious IFR cross-countries up and down the west coast.
The only weakness in the design has been the rubber hoses used in the pitot-static system, which could not stand up to the California summer heat.
Could you improve on the Zlin? I ask Koehler. As an aerobatic pilot Jeff of course wants more power to give more vertical performance. Handling is not a problem. In fact, it could not be better. Inside and outside maneuvers are performed routinely.
Flying the Zlin 242
Two-seat tourer or aerobatic trainer, the Zlin 242 excels at both. It is sturdy, agile and will cheerfully pull gliders or tow banners on its day off. (David Brown)I meet Jeff Koehler’s Zlin at Torrance’s Zamperini field on a sparkling summer day. It’s a neat two-seat aerobatic ship with a spiffy red, white and blue sunburst paint scheme. The Zlin is all-metal and has a large forward-sliding canopy, which promises to give excellent visibility.
We check the four fuel tanks in the wing. I note the neat fuel cap with combined dipstick for each tank. We will fly with only fuel in the mains today as aerobatics is not permitted with fuel in the outer wing tanks. The aux tanks increase fuel capacity from 32 to 60 gallons.
Construction is steel tube for the center fuselage and metal semi-monocoque for the rear fuselage. The metal tube center section has a sealed spar pressurized with nitrogen. There is a gauge in the cockpit to warn of any reduction in pressure, which would indicate leaks or cracks. Outer wings contain the auxiliary fuel tanks and composite upturned wingtips.
Composites are used for panels and fairings. Generous aerodynamic balances on elevator and rudder contribute to the light forces. The trailing edge of the elevator has a big trim tab and a servo tab to again lighten the loads. A glider/banner tow hook is located under the tail. We check the tricycle gear, which has large wheel pants to reduce the drag.
We check out the engine compartment. Unlatching three quick-release fasteners releases the hinged lift-up engine cowling on each side. This gives good access to the AEIO-360 engine and its tube mount, together with the oil system.
The nose sports an imposing three-blade MT constant speed propeller, a boon for serious aerobatics.
The battery installation sits behind the cockpit on the left hand side, reached by a neat-hinged panel. N242DC has been modified for twin 12v batteries rather than the original single 28v battery, which in early operations tended to leak acid during inverted flight. The present system does not leak. There is a Christen inverted oil system, good for a minute of inverted flight. The bubble canopy fits over the two-seat cockpit, sliding forward. It can be jettisoned in an emergency. There is room for baggage behind the seats under a plastic flexible cover, and fabric sunshades can be pulled forward inside the top of the canopy to give protection from the sun during cross-country flying.
For our evaluation flight, which will involve aerobatic flight in our local practice area over the Pacific, we put on flotation vests, then I don a back-type parachute, cinch it up and climb aboard over the trailing edge of the wing. The canopy is slid forward and a handgrip on the fixed canopy frame aids my access to the left side of the cockpit.
Carefully stepping down into the cockpit, avoiding the stick in front of the seat, I slide the seat back to its aft limit and strap in. Koehler straps into the right seat.
The cockpit of the Zlin shows its military background with hefty sticks and dual throttles. Flaps are operated mechanically by the large lever between the seats. (Dan Brown)The cockpit has a military flavor. The hefty control stick is in front of me, topped with radio and intercom buttons. I notice that the rudder pedals have toe restraint straps (for inverted flight), and we have elevator and rudder trims between the seats on the floor. We have individual throttles for our left hands while a substantial lever between the seats operates the trailing edge flaps.
Master switch on, fuel pump on and the AEI-360 is soon running.
We taxi out to the run-up area for 29R at Torrance. Koehler cycles the prop and dials in right rudder trim and takeoff elevator trim. Ready to go, we pull up to the hold-short line, close the canopy and get ready to fly. We are cleared for takeoff.
Jeff releases the brakes and we track the centerline, lift off and climb. Jeff brings the prop rpm back in deference to our local noise restrictions and then smartly turns right, then right again so we are climbing downwind. Abeam the tower we are cleared to turn right for the practice area, which lies to the south over Palos Verdes hill.
Jeff gives me control of the aircraft in the prescribed military manner, and I climb at 75 knots to 3,000 feet. The Zlin needs right rudder in the climb to keep the ball centered. As advertised, the controls are very light, so my initial moments include the odd wing wagging and pitch bobbles until I adapt to this very precise control system. Jeff’s description of “it handles like a jet fighter,” is proving accurate.
I top the ridge of the Palos Verdes Peninsula and coast out into the practice area airspace over the Pacific. The canopy comes down to waist level, and the resulting visibility is superb. Using a mountain peak on Catalina Island as a reference point, I do a couple of clearing turns. The ailerons are light, but adverse yaw makes it essential to use the rudder to keep the ball in the middle. I progress to steeper turns and continue to clear for other traffic. It’s a beautiful sunny day with a three-ship formation of T-6s practicing their join-up techniques below us, and at sea level, a blue whale is heading majestically westbound below us off Portuguese Bend, ploughing through the calm Pacific.
It’s time for aerobatics, and we clear the decks for action.
Jeff starts with a wingover and then a slow roll. Both are unerringly precise.
I try to replicate his roll. I’m too slow by 10 knots and untidy with a late rudder application. I blame a decade-long absence from aerobatics. Another roll with the correct 120 knot entry speed goes better.
Jeff demonstrates a loop. All is as it should be. We pull just over three g with an entry of 130 knots, float inverted over the top with wings exactly level, and recover.
I attempt a loop, misread my airspeed indicator (curiously on this East European ASI the needle goes twice round the dial) and enter the loop with insufficient speed, so we stagger over the top in a less-than perfect maneuver.
Jeff demonstrates a hammerhead, pulling to the vertical, surfacing the nose down through the horizon, then heading straight down for the ocean before pulling out, I attempt to replicate this and fail to get the perfect vertical, kick the rudder too late and again exit from the maneuver in an untidy manner.
We are now at 3,000 ft over the Pacific south of the Trump golf course and report our position over the radio while keeping a lookout for other traffic.
I progress to four point rolls, liking the ailerons more and more. They are light and effective. This is fun. Slow rolls can be really…really… slow. The five-point harness keeps me anchored to the seat, but while we are inverted, my checklist escapes and floats up to the canopy where Jeff retrieves it from mid-air.
I settle down to get a performance cruise point, and at 3,000 feet with 75 percent power, I eventually see 110 knots. To add speed, Jeff shows me the jet pilot trick of unloading slightly, which gets the plane accelerating without significantly losing height. Finally, we see a reading just shy of 120 knots.
It’s time to head back. Jeff gets the ATIS for Torrance and takes us back to Pt Fermin, then turns north for the Vincent Thomas Bridge, which is our entry point for rejoining.
Torrance Tower clears Jeff for the break. We come over the field at 800 ft, break left towards Palos Verdes hill for a landing, start the flaps down at 85 knots on downwind, then curve round in a descending 180 degree turn with full flap at 70 knots to a landing on 29L. We taxi back and shut down. I must confess to a hint of a grin.
This is a utility plane, designed for training, aerobatics, touring and glider towing (it has a hook under the rear fuselage). It excels at all of these tasks.
My thanks to Zlinmeister Jeff Koehler for letting me share his Zlin for the afternoon. It was a fun airplane.
Specifications for Zlin 242L
Engine AEIO-360-AIB6 200HP Fuel injected
Propeller MT 3-blade constant speed propeller
Dimensions
Span 30.64 ft
Length 22.77 ft
Height 9.68 ft
Fuel
Main tanks 2 x 16 US gallons
Auxiliary tanks 2 x 14.5 gallons
Range 267 nm (mains alone)
Range 570 nm with aux and mains together.
Performance
Rate of climb at sea level 1,080 ft/min
Max speed at sea level 127 knots
Cruise at 2,450rpm/6,560 ft 122 knots
Takeoff ground run 689 ft
Distance over a 50” obstacle 1,476 ft
Weights
Empty weight 1,642 lbs
Takeoff weight 2,140lbs
G limits
+6/-3.5
