Flying the Rotorway Exec 90 Kit Helicopter
RotorWay International’s kit contains surprisingly significant improvements.
More than five years ago, I flew and reported in KITPLANES on the Exec kit helicopter by RotorWay Aircraft, Inc., of Chandler, Arizona. Founded by homebuilt helicopter pioneer B J. Schramm, RotorWay produced the two-seat Exec 90 helicopter and offered flight instruction and builder support. RotorWay also manufactured the four-stroke, liquid-cooled engine used in the Exec, with parts cast in its own foundry.
Buford John Schramm’s Exec Helicopter
The Exec was an impressive aircraft: the culmination of more than 20 years Schramm devoted to practical, personal helicopters. Eventually, however, financial problems developed, at least partly because of the boom-and-bust real estate market in the Phoenix area, according to Schramm.
He says a major factor was the need to move the flight training facility and the foundry from Chandler, where previously open land adjacent to RotorWay’s property sprouted buildings that were incompatible with extensive helicopter operations. Including the cost of adding electrical, capacity at a new Phoenix RotorWay facility, moving the foundry cost some $200,000.
Two of RotorWay’s customers who built Execs and learned to fly them at the Chandler facility and who were to have a profound effect on the future of the project are John Netherwood of Yorkshire, England, and Dale Krog, a former AT&T executive from Illinois. Netherwood ran a large company that rented and sold forklifts, and he became RotorWay’s English dealer as a hobby.
In early 1990, as RotorWay’s creditor banks sought to salvage their investments, Netherwood made a successful bid for the assets and design rights and pledged to continue in the kit helicopter business. He named his new company RotorWay International.
In the meantime, Dale Krog — who had finished his Exec kit in 1983 and flew it extensively until he, sold it in 1986—retired at age 40 from AT&T and was hired by B J. Schramm to work on several helicopter projects.
Krog was one of a dozen longtime RotorWay Aircraft employees who Netherwood asked to join the new company. The result is that Krog is now vice president and general manager of RotorWay International.
After establishing the new company, one of Netherwood’s first acts was to gather together the 12 former RotorWay Aircraft employees, hand them each a blank sheet of paper and ask them to list improvements that should be made to the Exec.
Krog notes that there was considerable similarity between the separately written lists, which were combined into a final list of 18 changes that have been incorporated into RotorWay International’s product — the Exec 90. The first Exec 90 was finished in time to make its debut at Oshkosh last summer.
Significant Changes To The Rotorway Exec 90 Helicopter Kit
Some of the modifications are cosmetic, such as moving the switch console overhead in the cockpit. Some are aerodynamic , like the reshaping of the “doghouse” — the large fairing above the fuselage—for better airflow and higher cruise speed.
Some are mechanical, like improvements to the 162-cubic-inch, dual-electronic-ignition engine: new heads, new water jackets that smooth coolant flow, and larger, sodium-filled exhaust valves. The new main rotorshaft is longer (resulting in better pendulum stability) and beefier.
The updated RotorWay International Exec 90 kit helicopter cruises near 100 mph.
Wall thickness is greater and the diameter is now 1.75 inches, up from 1.625 inches. Netherwood credits the stiffer main rotorshaft with part of the rotor system’s improved performance, which allows cruise speeds of up to 100 mph and easy achievement of the Exec 90’s 115-mph VNE.
From an operational standpoint, however, maybe the most significant change to the helicopter relates to a 25-pound cylindrical weight that is shifted when switching from solo to dual flight. Dale Krog recalls that RotorWay Aircraft sales people didn’t volunteer information on why the original Exec had two battery boxes.
But when he asked before buying his kit, he was told that the battery had to be moved from one box to the other to change from solo to dual flight or vice versa. “I thought, ‘Okay, I’ll live with that.’ But they never told me that you also had to carry 20 pounds of weight on the skid, plus another 50 pounds in the passenger’s seat when flying solo.
“I wouldn’t have bought the Exec (if I had known) because of this problem: How do I fly it over to your place, pick you up, go fly somewhere, drop you off and come back home? What am I going to do? Leave 70 pounds of weight on the ground? And when I drop you off, throw rocks in the cockpit? That is how the original Exec had to be flown.” The new weight-shifting system solves this problem.
To change from dual flight to solo, the pilot removes the safety pin on a 25-pound weight that is attached to an external stub just aft of the engine and reattaches it on the right front skid tip. The process takes about half a minute. Unfortunately, the system is not retrofittable to earlier Execs because considerable structural changes had to be made to the Exec 90 to accommodate this feature.
Other significant changes to the Exec 90 made the 25-pound weight shift system possible. One was moving the location and tilt of the main rotor shaft slightly, a modification that involved redesigning major parts of the helicopter.
Still More Changes To The Rotorway Exec 90 Helicopter
Also included on the 18-point list is a new skid that has smoother curves and spreads stress out along the landing gear rather than concentrating it near the fuselage. Cabin eyebrow windows improve visibility. The new dual rotor/engine tachometer is easier to read than the two separate gauges previously supplied, and the new centered instrument console looks good compared to the old instrument arrangement at the base of the windshield.
The tailcone and rotor blades are now made of 0.025-inch aluminum alloy instead of 0.020-inch material. That change has extended considerably the life of the tailrotor blades, which previously had to be replaced every 250 hours. (RotorWay believes that the new tailrotor life may be more than doubled. Experience with the first prototype will determine the expected life.)
Also in the area of improved durability are secondary drive unit pulleys, which are now anodized. And the exhaust system collector (the pipes from the manifold to the muffler) are now made of stainless steel.
Engine inspection and maintenance are easier on the Exec 90 because of split upper fiberglass cabin panels, which means you no longer have to dismantle the entire fuselage shell to get at the engine.
Another item in the operational/cosmetic category is a nice touch: multi-switch cyclic (stick) grips. There’s no trigger for shooting rockets, but the new grip includes push-buttons for intercom, radio transmitter and engine starter.
A Rotorway Factory Tour
A walk through the factory with Netherwood and Krog offered some insight into the company’s plan for success. The unused foundry is silent, but the rest of the plant is filled with high-tech machinery and the few employees needed to turn castings and billets, steel tubing and fiberglass parts into engines, pulleys, fuselage structures and shells.
A computer-numerically-controlled (CNC) Toyoda four-axis vertical mill, tended by one machinist, was busy turning an aluminum casting into an engine block during my visit. Crankshaft castings were being checked by Magnaflux for imperfections before their turn on the huge CNC lathe in another part of the machine shop.
One welder was at work with an oxy-acetelene torch on a steel-tube fuselage (the fiberglass shell is non-structural), and another was TIG-welding a critical part. Krog noted that TIG-welded parts are stress-relieved. He and Netherwood also mentioned that the Exec 90 builder has to do some welding for himself. Control-system parts, such as the pair of collective pitch arms, require welding by the kitbuilder.
Precision and quality control are critical to the development of a safe helicopter and RotorWay’s shop procedures show it. I was introduced to a technician who was setting up an electronic coordinate-measuring machine used to ensure that first articles produced by each new setup of the CNC machines meet specifications.
Also, every example of some parts, such as mainrotor shafts, is checked by this technique. Some components, such as the sprocket pulleys in the drive system, are subject to a complex series of machining and heat-treating steps that result in lead times of as much as five months, Krog noted.
“We have more complexity in our rotor system alone than most kit airplane manufacturers have in their entire airplane,” he said. Could be. In any case, the complex work is all done at the factory; the entire mainrotor system, including shaft, swashplate parts and linkages, comes assembled.
I looked at the modified dual-throat carburetor, which includes a manifold for carburetor heat that is warmed by engine coolant. The throat walls — not the incoming air—are heated, resulting in none of the usual power reduction from heated-air systems, Netherwood explained.
The factory system for stocking, distributing and packaging everything from the single-piece acrylic windshield to the smallest washer appears neat and efficient. Most small parts are plastic-mounted on cardboard in logical order. Factory-built and matched rotor blades are packed in one of the 13 cartons that comprise an Exec 90 kit.
The cost of crating (included in the price of the kit, incidentally) has gone down, as the old Exec kit used to require 29 cartons. Several Exec 90 kits were in the final stages of being prepared for shipment during my visit.
A total of 29 employees, including Krog, are on the payroll, and production has just been increased from eight to 10 Exec 90 kits per month. Netherwood believes that if sales warrant further changes, as many as 250 units per year could be manufactured by going to a second production shift.
What Do You Get In The Rotorway Exec 90 Helicopter Kit?
Nearly everything to build an Exec 90 comes in those 13 cartons. Exceptions are paint, flight instruments (air-speed, altimeter, compass and VSI) and avionics. Among the few options offered by RotorWay International is a VAL transceiver and an intercom.
Seats, upholstery, engine instruments and every part to build the electrical system are included, unlike many complex aircraft kits. The builder’s manual has been revised recently, expanding the “see – do” section with more photos and descriptions.
Especially helpful will be the new system schematics, such as the electrical layout. Photos show installed equipment, and the wire list describes every wire and connector. The system drawing makes clear where every wire goes. A similar schematic drawing of the engine coolant system should preclude a lot of phone calls from otherwise-confused builders, Krog says.
Finishing the project should be an achievable task. Krog’s Exec, a first-time homebuilt project, took him just over 600 carefully logged hours to complete and prompted him to call the factory three times for help. That may be a record low number of calls, but the new manual and drawings should help considerably.
Once finished with the project, the Exec 90 owner will have a 925 – pound, piston-powered, two-seat helicopter capable of lifting 500 pounds of useful load including 17 gallons of fuel. The machine will hover in ground effect up to 7000 feet (5000 feet out of ground effect), climb from sea level at about 1000 fpm, and cruise 180 miles in 2 hours.
The main rotor system uses a two-blade, semi-rigid rotor with asymmetric metal blades and an elastomeric hub that eliminates the need for lead/lag and flapping hinges. The tail rotor is driven by three V-belts in series that are joined at their ends by pendulum-mounted pulley systems that require a single-point tensioning adjustment.
As in small FAA-certified piston helicopters, power is taken from the engine via parallel V-belts. A single, triple-link chain drive and sprocket system substitute for the more-common geared helicopter transmission.
The chain, which is replaced at 100 – hour intervals, is simpler to inspect and maintain than a gear-type transmission, RotorWay says. The cost of all time-compliance parts—mostly bearings—is so low that Krog is afraid experienced helicopter pilots won’t believe it. But he will share the details with interested potential customers.
Marketing The Rotorway Exec 90 Kit Helicopter
RotorWay International is planning to establish an overseas distribution system, but in the U.S., Exec 90s will be sold direct, allowing the factory to maintain coordination between production and promised delivery—in addition to controlling customer technical support. Decisions regarding direct sales of kits, more efficient packaging, and use of off-the-shelf systems such as the new capacitive fuel gauge, have resulted in keeping the kit price to a minimum, Netherwood says.
Systems formerly listed as options—such as dual controls, the elastomeric rotor head, and the stainless steel exhaust collector — are all standard. After a period of selling the first batch of Exec 90s at come-on prices, RotorWay International has just announced a new price of $42,500 (1991 list price) for the kit.
As of late February, the backlog of orders was about two months. The customer deposits $5000 and is notified to send the balance a week before delivery. Netherwood stressed that parts are not back ordered; complete kits are shipped “on time or early,” he said.
There is some flexibility if a customer wants to postpone delivery briefly and another asks for an earlier delivery position. But Netherwood emphasized that he is not using one customer’s money to finance a previous customer’s kit.
Let’s Go Flying The Rotorway Exec 90 Kit Helicopter
Up front, it’s necessary to say that I am not qualified to evaluate helicopters in great detail because I’m not rated in them. But despite the considerable lapse of time since I last flew in an Exec — more than five years—the memory of the week of RotorWay training remains vivid, and some impressions and comparisons between the Exec and the Exec 90 will be valid.
Currently operating at Glendale Airport west of Phoenix, the RotorWay International training program will be moved near the end of the year—along with the rest of the company—to a 4-acre site already purchased at Stellar Airpark near Chandler.
Training is organized into several phases under chief flight instructor, pilot examiner and customer service head Stretch Wolter, who has been with the Exec program since long before I first trained with him in late 1985. Phase 1 is basic hover training; Phase 2 covers forward flight and the rest of the maneuvers required for a private helicopter license.
Each of these phases—which are organized to take one week—currently costs $1000. Some people require more than one go at one or both training phases. Phase 3 ($500) is preparation for the private pilot check ride — and the flight itself with Wolter.
The successful check ride results in a private helicopter license or helicopter rating add-on for pilots already licensed. Training prices may go up with the beginning of the new season, which starts in late September. Phoenix weather is too hot for training between June 1 and late September.
Wolter interrupted his four-man class to take me flying. A careful pre-flight of an Exec 90 includes a cockpit and external check (including rotor bolts and linkages and the proper placement of the movable weight) plus turning the main rotor blade 90° to the fuselage. Moving the blade accomplishes three things:
It checks the smoothness of the rotor system when moved forward, it verifies the operation of the one-way autorotation sprag clutch when pushed backward gently, and it ensures that you’ve untied the main-rotor from the tail boom.
Startup is as simple as in an airplane and is done only after clearing the area and centering the cyclic (control stick) and raising the collective pitch lever off its stop to about knee level. The rotor begins spinning as soon as the engine starts, even before the manual clutch idler control is engaged.
Getting engine temperatures into their green arcs takes a few minutes. When ready to fly, the pilot rotates the handle on the end of the collective pitch lever outboard — motorcycle style — to run both engine and rotor tachometer needles into their green arcs. The new dual-tach gauge makes it easier to track both rotations at a single glance.
Wolter let me lift off, but he was on the controls if needed. Climbing into a hover a foot or so off the deck, I nudged the controls some, trying to be gentle, but succeeding in flopping around the ramp maybe 5 feet from where I was trying to keep the helicopter. Wolter could tell right away that I was looking too close to the helicopter’s hover point rather than at a more distant point on the ramp.
After he mentioned that, I settled down and more or less stabilized the hover; but he soon noted that I was pressing both pedals when pressure was needed only on the right one to compensate for hovering torque. Fixing that helped too, and he then had me make a pedal turn to the right while maintaining something close to a fixed position on the ramp.
The 2 or 3 minutes of this exercise weren’t enough to allow me to relax completely, but I could see and feel considerable improvement in this time. With regular practice, hovering could again become a natural act.
Wolter called Glendale Tower for a departure across the runway to the east, and I monitored as he accelerated to more than 40 mph before climbing much—staying under the dead man’s curve portion of the height-velocity chart. (To make a safe autorotation landing , a helicopter needs either altitude or airspeed or both.
Climbing steeply or straight up would place the helicopter in a position from which a power failure would cause a sink rate too high to arrest with the power stored in the rotor system, even with immediate reduction of collective pitch.) At 500 feet or so, Wolter demonstrated smooth flight at 80 mph, but noted that my light weight would result in vibrations at faster speeds.
Sure enough, at about 85 mph we could begin to feel low-frequency, mainrotor vibrations. Even at 100 mph, however, the vibration was tolerable. For cross-country flying with only a pilot or a light passenger on board, ballast would be added to allow comfortable flight at a cruising speed of 90-95 mph.
Slowing to 80 mph again, Wolter turned the controls over to me, and I found that a slight amount of forward cyclic pressure — probably because I am lighter than standard — was needed to achieve balanced flight, that is, to keep me nose from rising. As Wolter noted, a yaw string taped to the windshield helps you know which pedal to press for no-yaw flight.
In the Exec 90, with its clockwise-turning mainrotor (as seen from the top), fast flight requires a bit of constant left pedal (don’t call it rudder in a helicopter). At least at our particular flight configuration, the Exec 90 tended to pitch up or down slightly, requiring correct anticipation’ to fly smoothly.
The trick is to anticipate what the nose will do next and put in a small correction before the undesired motion gets a good start. The situation is not much like the corrections made when flying an airplane. A somewhat better analogy is flying a glider on a towrope behind an airplane.
An experienced glider pilot can anticipate where the glider will want to move next—and preclude the move with tiny pressure corrections on the controls, resulting in what appears to be effortless and perfect positioning behind the towplane. Having flown gliders since the early ’60s, I’ve found those moves are second nature, but helicopter moves are not; I bobbed along and never really relaxed.
With Stretch Wolter on the controls, the helicopter was as steady as my glider on a towrope, proving that my technique—not the helicopter—was the culprit. Helicopter turns are different from turns in airplanes, too. Wolter caught me trying to use the pedals like rudder pedals in an airplane or glider, and that’s wrong.
In a helicopter, there’s usually no need to apply different pedal pressure when entering or rolling out of a turn. (Rudder pedals in an airplane are used mainly to compensate for adverse yaw caused by the downward-moving aileron, and there’s no such device on a helicopter.)
Helicopter pedals are moved or pressured to change the required compensation for main rotor torque, such as when hovering, which requires a lot of torque compensation with the power pedal—under the right foot in an Exec 90. Basically, helicopter controls need to be moved smoothly and early to be done right; jabbing at the controls won’t do. All of this takes practice.
Improved visibility through the new eyebrow windows became apparent in the first turn; there was no longer any need to duck below the edge of the door to look for traffic. Wolter made the airport approach and then let me practice hovering for a few moments.
I then landed rather firmly from a 1 – foot hover, making it a point to keep the cyclic lever moving down after the first skid contact with the ramp. I could have been a bit more gentle. “You gonna log all three landings?” Asked Wolter, who is not one to let small things pass.
Rotorway Exec 90 Kit Helicopter Safety
Wolter’s teaching and check rides are probably one reason that his successful former students have a good record in their Execs. I asked if the training syllabus has been modified over the years in response to the problems people have had. The answer is yes.
Whenever Wolter learns of an Exec accident or incident, he gets details from the pilot and amends his training procedures as appropriate. For example, he noted that the preflight checklist was modified some time back after a pilot let the end of a seat belt get into the collective pitch control slot, causing it to bind.
Rotorway Exec 90 Kit Helicopter Summary
So far, things are looking up for John Netherwood, RotorWay International and the Exec 90. He expects to sell his Phoenix factory and move into the new Stellar Airpark site by year’s end. We’ll use the completed move as an excuse for another visit and a brief report next year. Maybe we’ll even get to do some more flying. Five years between helicopter flights—especially in a product as nice at the Exec 90—is too long.
|RotorWay International Exec 90 Helicopter Kit Specifications|
|Rotor area||490.8 sq. ft.|
|Fuselage length||22 ft.|
|Landing gear type||skids|
|Skid track||5.4 ft.|
|Gross weight||1425 lb.|
|Empty weight||925 lb.|
|Useful load||500 lb.|
|Disc loading||2.9 Ib./sq. ft.|
|Power loading||9.5 Ib./hp|
|Fuel capacity||17 U.S. gallons|
|Payload (full fuel and oil)||388 lb.|
|Engine||RotorWay 162-cu.-in., four-cylinder, dual ignition, dual-throat
carburetor, liquid-cooled, four-stroke.
|Mainrotor||Asymmetrical, semi-rigid-rotor, two-blade, teetering metal
|Maximum speed (sea level)||115 mph|
|Cruise speed||90-100 mph|
|Rate of climb (sea level)||1000 fpm|
|Service ceiling||10,000 ft.|
|Hover in ground effect||7000 ft.|
|Hover out of ground effect||5000 ft.|
|Other pertinent notes||Kit is complete except for flight instruments,
paint and avionics.
COURTESY: Kitplanes Magazine June 1991 – Subscribe here.
Specific Piloting Notes For The Rotorway Exec Helicopters
It is possible for the left cyclic to be restricted or obstructed if the user has large thighs.
Check that you can reach full left pedal without your leg extending straight or the heel of your shoe catching on the lip of the floor pan.
Don’t rush your take off to the hover – always double check that the ballast weight is in the correct position.
Stay in a low (2ft) stable hover until you have RRPM at the top of the green and have verified manifold pressure available above what is required in the hover. From this, determine your safest take off profile.
If manifold pressure is limited in zero wind conditions, use the pedals to hold the nose in the two o’clock position in relation to your take off line. As you move forward along the line, push in left pedal – this will reduce the power required by the tail rotor and give you that extra half or one inch of MAP to move through transition.
COURTESY: Brumby Helicopters Australia.