One of the most common questions I’m asked at air shows and speaking engagements is, “Why do new General Aviation airplanes cost so much in contrast to even a high-end sports car?” I probably don’t have any better answers than anyone else, but I can guarantee you one major reason is that the market is so much smaller.
Like many of you, I subscribe to several car magazines, and I’m as much a fan of BMWs and Porsches as the next guy. I’m also just as intimidated by their price tags, but the law of supply and demand is a prime directive. If the car companies could build more units, the prices would come down.
A Premier Choice in Its Day
The 421’s fuselage and wing served as templates for the later turboprop Conquest II and I (produced in that order), and the top piston Cessna was almost universally considered the peak of the piston pyramid. As the premier entry in the class, with up to eight seats, a pair of low-revving, geared, 375-hp Continental engines, and a cruise speed better than 220 knots, the 421 quickly assumed the mantle of the most popular and in-demand mode of corporate transport on avgas.
An efficient air conditioning/heating system kept everyone comfortable, and the pressurization system provided air compressed to the equivalent of 8,000 feet while the airplane cruised at FL250, well above 80 percent of the world’s weather and turbulence, most often cruising in smooth air and sunshine. That’s exactly the scenario CEOs and executives of mid-level companies expected of a corporate transport.
The Cessna 421 Golden Eagle, as it was named, seemed to offer it all. Everyone boarded through an airstair door at aft left, and, once seated, passengers luxuriated in a business-class enclosure with dimensions appropriate to the price tag. The cabin was generous, accommodating pilots and passengers in a space that measured 55 inches across by 51 inches tall. It wasn’t standup headroom, but the aisle was wide, and climbing into any seat was a pleasure.
Better still, once you were settled into your bucket, you were typically wrapped in leather, adjacent to fold-down convenience tables. Even the original 421s could be ordered with a wide variety of electronic conveniences, sporting such accoutrements as individual DVD players, game stations, and iPod outlets, plus the usual intercoms, in-flight phone, and even teleconferencing capabilities.
From a pilot’s point of view, especially pilots entering the corporate world in the late 1960s/early 1970s, the 421 must have seemed a monster, nearly 7,000 pounds gross in 1968 and 7,500 pounds on the later models. For an entry-level business airplane (compared to turboprops and jets), the Golden Eagle was a complex machine, fitted with some of the most sophisticated systems in General Aviation. Contrary to sometimes popular belief, turboprops and jets are often easier to fly than the top-level piston twins.
Engine Specs, Altitude, and Speed
The engines required more than a little study. The 421’s powerplants were various dash letters of the Continental IO-520s. As the designation implies, these were 520-cubic-inch engines, and Cessna used variations of the type on a wide variety of its models. These Continentals were rated between 250 and 375 hp, and Cessna employed them on the company’s big-bore products, from the single-engine Stationair and Centurion to the twin-prop 303, 310, 320, 335, 340, 401, 402, 404, 411, 414, and 421.
The 421’s variation was, predictably, the largest and most powerful of the group, specifically the GTSIO-520-N, a geared (G), turbosupercharged (TS), injected (I), opposed (O) mill approved for 375 hp. The turbocharger had a critical altitude of about 18,000 feet, so the airplane could maintain 75 percent power at 25,000 feet. Technically, the 421 was alleged to have a service ceiling above 30,000 feet, and in the old days when there were no limitations on altitude, some pilots did try to cruise at such tall heights.
Today, reduced vertical separation minima (RVSM) rules have made flying above FL280 more expensive, so few 421s are certified for operation at the top of their ceiling (assuming you could get there in the first place).
Climbing to altitude was expedited by a power loading of less than 10 to one, one of the primary indicators of efficient climb. In an ascent from sea level, the 421 could manage 1,800 feet per minute (fpm) or more, allowing climb to the lower flight levels in less than 15 minutes. A climb to the airplane’s optimum height of 25,000 feet required less than 25 minutes.
Once you were established at your chosen altitude, speed could be pretty much as you liked it, depending upon how much fuel you were willing to pour through the engines. Max cruise at 75 percent demanded about 20 gallons per engine per hour, but the reward was cruise speeds in the area of 220 knots. Standard fuel capacity was 213 gallons, so a trip at max cruise allowed the airplane to linger aloft for 4.5 hours and cover 1,000 nautical miles (nm) in the process. Optional, long-range fuel capacity was 262 gallons, a worthwhile option for corporate flight departments that needed to travel long distances.
To increase range and reduce fuel burn, smart pilots reduced to 65 or even 55 percent power, still traveling at 200 knots and extending range to 1,200 nm, enough to cross the lower United States with one stop in a single day.
The 421’s engines were initially demanding machines, rated for only 1,200 hours on the early models, one of the lowest TBOs of any modern engine. Because the cost of an overhaul is expensive, there’s a strong incentive to treat them gently. (Later versions on the 1978-and-later 421s were rated for 1,600 hours.)
Ham-handed slamming of throttles fore and aft has always been regarded as a bush-league technique on any airplane, but the gearing system on the 421 demanded kid-glove treatment. Power applications had to be slow and deliberate, and power reductions needed to be even slower to avoid any possibility of shock cooling. Engines are constructed of a number of metals with different rates of expansion and contraction related to temperature change, so the slower you change internal operating temps, the better. Some pilots even used the rule of no more than one inch of manifold pressure reduction per minute. That’s probably a little extreme, but it was important to keep throttle jockeying to a minimum.
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