|Cessna 170B: Predecessor to the Skyhawk|
|Written by Bill Cox|
|Thursday, 24 February 2011 15:16|
Depending upon your point of view, the 1940s were either the best or the worst time for General Aviation. In those days, new aircraft manufacturing projects were springing up everywhere in anticipation of the thousands of World War II pilots returning from overseas.
Unfortunately, many of those companies went out of business as quickly as they opened their hangars and realized the market simply wasn’t there. Sales were slow, and many of the start-up companies that materialized in 1946 and 1947 folded by 1948.
One that didn't, however, was Cessna Aircraft Company. Like Piper and Beech, Cessna had the staying power to survive until the market really did recover, and that began to happen in the early 1950s. Cessna offered the Model 170 as its everyman's family airplane.
Even today, the type is fairly common on the General Aviation market. Inevitably, however, some readers will be unfamiliar with the 170, as it is, after all, at least 54 years old.
The model was born in the late 1940s as a stretched and powered-up version of the two-place Cessna Model 140. It was an entry-level, single-engine four-seater, targeted at what was assumed to be a plethora of World War II pilots eager to continue their love of flying. There was just one problem, however; few returning Army Air Forces and Navy aviators had money to buy new airplanes.
Cessna could not possibly have imagined how popular the 170 and its follow-ons would become. The 1948 Cessna 170 premiered at an average-equipped price of $7,075, and if that sounds like a bargain by today's standards, consider that it nevertheless represented a substantial sum in 1948 dollars. By 1953, the average-equipped tab for the updated 170B had risen to $10,040. (As a point of reference, the 2010 Cessna 172S Skyhawk had a base price of $301,500.)
The original 170 featured fabric-covered wings, V-formation support struts, and an aluminum fuselage, along with the Continental C145-2 engine that was to become standard on the type. That first 170 also mounted three C-140 fuel tanks, two in one wing and one in the other.
In 1949, Cessna added a dorsal fin, converted the V-strut to a single support, and metalized the wings to offer an all-aluminum airplane, not surprisingly designating the modified Cessna the 170A. The new variation also included the vertical stabilizer and rudder configuration utilized on the Cessna 195.
The Cessna 170B came along in 1952 and featured what Cessna called Para-lift flaps, large, slotted, semi-Fowler designs borrowed from the L-19 Bird Dog military airplanes. These translated aft as they extended down, increasing lift dramatically. The 170B offered positions for 0, 20, 30, and 40 degrees, and later models featured an extra 10-degree flap position. Cessna’s last 170 also benefitted from mass balance weights on the elevator that eased pitch response, a revised tailwheel, and larger side windows.
Neither the 170A nor 170B were approved for slips with full flaps extended for fear of blanking the tail and reducing elevator response. The original 170 was an excellent slipping machine.
The airplane featured here is a 1953 170B, and it is probably as faithful to the original configuration as any example you'll find. Today’s price for a reasonable Cessna 170B is reportedly $24,000, not bad for a 2+2 family hauler. If you’re looking for a fully restored airplane with modern avionics, plan to spend another $10,000-$20,000.
For the record, there are three slightly different wings used on the 170s, though all used essentially the same NACA 2412 airfoil. The 170A featured a wing with no dihedral (thus the nickname, the “flat-wing Cessna”), whereas the original 170 had one degree of dihedral, and the later 170B sported three degrees of dihedral.
Cessna couldn't help but take note of Piper's success with the Tri-Pacer, a tri-gear version of the Pacer, and that fostered the development of an equivalent, tricycle-geared variant of the 170B. Cessna introduced the tri-gear 172 in 1956, and that signaled the end of the 170. At the time, Cessna already had a good, four-seat taildragger in its stable, the 180, and the 180 was the stronger and more capable short-field airplane with a better payload. It was felt the 170 should be retired to make way for the 172.
Despite the spreading belief that tricycle gear was the wave of the future, Cessna apparently had its doubts about prospects for the new model, however, as the original 172 was certified under the 170’s type certificate. Only later did the 172 earn its own production authority.
In total, Cessna constructed just over 5,000 Model 170s, not bad for only eight years of production, especially by today’s standards when some manufacturers celebrate producing 100 of a given type a year. Slightly less than half of those 5,000 Model 170s are still on the aircraft registry today. In contrast, Cessna’s 172 was even more widely accepted by the pilot public. That original Skyhawk has spawned something like 40,000 copies over the last 54 years of discontinuous production.
It should come as no great surprise that the 170 and 172 shared equivalent performance, since both airplanes operated with essentially the same wing and the same engine. Standard power for both models was a Continental 145-hp mill that was allegedly up to the task of transporting four folks.
In fact, the more common payload was 2+2 – Mom and Dad up front and two kids in back. Using the comparative numbers for a typical 170B and an early 172, gross weight of both airplanes was 2,200 pounds, and empty weight on the 170B and 172 was 1,205 pounds and 1,260 pounds, respectively. The difference was, obviously, in the additional weight of the nosewheel on the Skyhawk, since hardly anything else changed.
In theory, the 170’s 995-pound useful load was enough to transport a full 37.5 usable gallons of fuel plus four, full-sized adults and some baggage. That actually may have been possible on a few of the early airplanes. Imagine that, a four-seater that could fly with full seats.
In reality, empty weight was rarely as good as the manufacturer’s claim, partially because of a naturally higher base weight and also because optional equipment usually exceeded the standard assumption. Another reality of older machines is that airplanes, like people, tend to gain weight with age.
The bottom line was that many Cessna 170s could legally carry full fuel, three folks, and some baggage without problems and still remain within acceptable weight limits. The featured airplane sported a fairly representative empty weight of 1,383 pounds, so useful load was 817 pounds. With full fuel, the airplane could fly with 595 pounds of people and stuff. The CG envelope was/is wide and forgiving, and C-170 pilots could load the airplane as necessary without concern for flying outside the box.
Stall speeds of the 170 and 172 were identical at 45 knots, and stall characteristics were the same for both machines, totally docile and forgiving. Climb rates were also very similar at about 650 fpm, and service ceiling was pegged at 15,500 feet, enough to top any mountain in the lower 48 states.
Neither the 170 nor the 172 was anyone’s idea of a speed demon. Cessna promised a cruise speed of 104 knots on the original 170 and 107 knots on the 172, and, for some pilots, that defied logic. Both airplanes were certified at the same gross weight, and the 170 flew with a relatively low-drag tailwheel, whereas the 172 had the obvious aerodynamic disadvantage of a nosegear. Probably just a glitch in the numbers. (In contrast, the modern Skyhawk S manages more like 125 knots at max cruise, though it does enjoy the benefit of 35 more horsepower.)
Cessna has always prided itself on handling that could best be described as benign. Just as with cruise speed and climb, the 170 doesn't do anything with alacrity, but that's a benefit that helps keep low-time pilots out of trouble. The airplane maneuvers with a gentle roll rate and moderate pitch response, neither of which is quick enough to outpace a fledgling aviator. The airplane’s stall is extremely docile with no tendency to drop a wing, provided you keep the ball centered. Recovery is a simple matter of reducing back pressure, adding power, or doing both.
Cessna 170s enjoy reasonable short-field performance and, in fact, are sometimes used in a bush capacity in Canada and Alaska, especially with engine conversions available as high as 220 hp. A 180-hp Lycoming is probably the most popular conversion, improving climb and takeoff performance. The type also is adaptable to skis and floats, another obvious benefit for bouncing around the boonies. If you're willing to fly the Cessna at the bottom of the envelope, you can ground a 170 to a full stop in well under 1,000 feet. The critical number, of course, is takeoff distance, but even that is less than 1,000 feet.
Landing characteristics are typical tailwheel, challenging in a crosswind but not beyond the talents of most reasonably trained pilots. There’s little question, however, that the tri-gear 172 is the easier airplane to handle during transitions to and from land. In all modes of flight, the two airplanes are virtual equals.
The debate as to which Cessna is best will probably never be resolved. Certainly, the 172 wins the popular vote, and aviation’s purists will probably always select the 170.
Whichever model you choose, the good news is that you’ll be flying one of the safest airplanes in General Aviation – and that’s the ultimate bottom line.
From the December 2010 issue of Cessna Owner