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Home185 Story

The C-185 Story

                        - taken from "Cessna Wings for the World” by William D. Thompson

As the C-170 evolved into the tricycle gear C-172 and the C-180 evolved into the tricycle gear C-182, it became apparent that these airplanes were becoming the favorite "easy-to-land" personal airplanes of the late 1950's. Thus the C-180 was moved almost exclusively into a utility airplane role. This was illustrated by a precipitous decline in annual C-180 unit sales from a high of 891 planes in 1956 to only 250 planes in 1958 when the C-182 hit its stride in the marketplace. Although the C-180 represented a better match between engine and airframe, in the author's opinion, it was obvious that an on-purpose utility airplane was needed for the bush country for heavy-hauling on wheels, Edo 628-2960 floats, and Fluidyne C-3200 or C-3600 wheel skis. This prompted the design of the C-185 in 1960, featuring a Continental fuel-injected 260 hp engine and a 1620 pound useful load that was 6 1/2% greater than its 1520 pound empty weight. In later years, this percentage increase became 9% which was phenomenal in that time period.

To accommodate the increased payload, the baggage compartment was lengthened 32 inches (mainly to stow unused seats from the cabin or up to 50 pounds of light but bulky articles). In addition, a large cargo pod capable of carrying 300 pounds, was designed to fit on the airplane's belly. Project pilot Bob Crawshaw irreverently referred to it as a "scrotum", much to the chagrin of our sales pilots. It produced a speed penalty of 7-9 mph and a climb penalty of 40 feet per minute. The middle and third row seats were rather spartan and quickly detachable to make room for bulk cargo in the cabin.

With a projected landplane gross weight of up to 3350 pounds in future model years, our design engineers had to beef-up much of the airframe structure as well as providing stronger wheels, axles, and landing gear.

Fuel System

To eliminate the possibility of the fuel-injected engine from sucking air from a dry tank, a fuel accumulator tank was installed in the belly of the forward fuselage. For simplified fuel management, only a fuel shutoff valve knob was available to the pilot. However, the tanks did not always feed evenly, and the demand for selective tank feeding prompted an optional LEFT - RIGHT - BOTH ON selector valve in addition to the remotely-located shutoff valve' In addition to a fuel flow (pressure) gauge, a rather complicated split-rocker type auxiliary fuel pump switch was installed. The right half had HI, LO, and OFF positions while the left half had MAX HI and OFF positions. The MAX HI position was available for emergency high power operation with an inoperative engine-driven fuel pump or to purge vapor in "heat soaked" fuel lines prior to starting a hot engine on the ground. With this amazing variety of fuel flow rates from identical switches in both the C-210 and C-185 (and later in the C-205, 206, and 207's), it was interesting to observe the "hot-starting" techniques of the various project test pilots. As an infrequent pilot in these airplanes, my hot-starts were often difficult. In contrast, the project pilot played those switches like a piano and consistently got an immediate start. One can imagine our challenge in developing a single recommended hot-start procedure for the owners' manuals. This was particularly important in the C-185 floatplanes where an immediate engine start was required after the floatplane was pushed from a dock into a fast-flowing river. It is quite probable that each bush pilot improvised his own hot-start procedure with great success, because we did not receive the anticipated complaints from the field.

Engine Mount

As in the C-180 floatplane, the C-185 floatplane and amphibian were fitted with a structural steel tub V-brace between the top of the front door posts and the cowl deck. This was in close proximity to the compass mounted on the windshield, and, of course, residual magnetism in the brace prevented the compass from being compensated accurately. To eliminate this magnetism, our mechanics had to apply a vibrating device against the brace and, in some cases, the aluminized iron firewall and other steel parts in the forward fuselage. We called it "growling" the brace or firewall. I often wondered if these items stayed "de-magnetized" during the life of the airplane.


The amphibian version with Edo 597-2790 amphibious floats presented a challenge on how we could discourage gear-up landings on runways and gear-down landings on water. Our standard landplane retractable gear warning lights were amber in color with gear up and green in the gear-down position. After much discussion and argument, we chose an amber color for the gear-down condition and a blue color for the gear-up condition. In those days there were no requirements or guidelines in the FAA regulations for gear warning light colors in amphibians. The reasoning for our choices were that blue related to water and amber related to an earth color. For obvious reasons, red could not be used.

Despite this "faultless" reasoning, I recall much confusion by experienced floatplane pilots being checked out in their new C-185 amphibians. The author would lecture these pilots on the catastrophic results of a wheel-down landing on water. It was urged that the pilot loudly proclaim (3 times) "I'm landing on water with the gear up" and, if possible, get an acknowledgment from his passengers). On more than one occasion an impatient customer would recite this phrase only to be reminded on final approach to a lake that his landing gear was extended! It is amazing how we are conditioned to lower a landing gear on any approach.

We heard a humorous (but almost tragic) story of an amphibian pilot landing after dark on the East River in New York with the gear inadvertently extended. At touchdown the amphibian nosed over violently, momentarily stunning the pilot. As the airplane settled nose-down and started to sink, he panicked and planned to climb back to the rear seat and kick out a side window which was still above water. In the darkness, as we heard the story, he unfastened his trouser belt instead of the seat belt. After finally getting the seat belt unfastened, he started to climb over the backs of the front seats. At that point, his trousers slipped down to his knees! In his words, "I almost drowned before I could get my pants back up and kick out the side window."

Dorsal Fin

The most distinctive feature of the C-185 is the large dorsal fin which was needed for preventing rudder lock (from extreme angles of yaw in power-on directional stability tests) in the floatplane. Since the tailwheel steering system had been perfected in the C-180 landplane, we believed that the increased weathervaning tendencies due to the large dorsal fin could be controlled in long taxi runs in strong crosswinds in the C-185 landplane. This belief was confirmed and, in fact, the same dorsal fin was adopted in late model C-180 landplanes for commonality on the production line.

This larger dorsal fin also made the pilot hold greater rudder deflection in crosswind landing drift correction. This, of course, would cause the steering chains to hold the tailwheel in a misaligned position at touchdown, promoting a violent shimmy in some cases. Thus it was necessary to install a manual tailwheel lock as an anti-swivel device. The locking lever, located on the cabin floor console, controlled a spring-loaded locking lug on the tail wheel assembly. This device was used, as desired, before each landing. Typically, it was used mainly in crosswind landings to keep the tail wheel aligned straight ahead while the rudder was used independently for directional control in the early phase of the landing roll.

Bruce Barrett recalls,

    "the agonies we went through making the camber-lift 180-185 floatplanes comply with contemporary hardline FAA requirements for (primarily) directional stability and control. The first 180J/A185F floatplanes had the big dorsal added to the 180, a ventral fin, and some rudder centering springs. This was not received well in the field and resulted in the author's and Ted Moody's trip north and Bill Bergman's and my trip South to survey floatplane operational requirements.

    I remember one belligerent pilot in the New Orleans area proclaiming his lack of need for #,any kiddie car springs". He was a real pilot! To confuse things further, the New Orleans GADO misinterpreted the maximum demonstrated crosswind figure of 12 or 13 knots to be a limitation which severely limited the Louisiana operators.

    As a result of all the field antagonism and confusion, additional development was accomplished through a lengthy flight test program. Ultimately, the ventral addition was eliminated and a nonlinear spring system was added to the rudder control circuit to provide adequate PAR centering in flight, but not overly penalizing water maneuvering through excessive pedal forces. Lots of things were tried and lots of hours were flown. The final configuration was apparently accepted."

A cargo pod was installed on the A185F floatplane prototype. However, one flight showed such marked deterioration in lateral and directional behavior that it was quickly removed and wasn't offered.

In 1970, the A185E Agcarryall was introduced, featuring an optional side-loading door on the left fuselage for easier loading of bulky cargo. Then in 1972, a sprayer version was offered with an external 151 gallon chemical tank under the belly, removable spray booms, a wind-driven spray pump, windshield wire cutters, and a vertical tail cable deflector. The spray valve handle, fan brake control, dump valve handle, boom pressure control, emergency spray tank release handle, and pressure gauge were mounted in an array adjacent to the copilot's side window. This 'version was intended as a part-time spray plane, because the Agwagon, as a full time spray plane, had already been introduced in 1965. Perhaps the main incentive was a method of circumventing embargoes against the importation of Personal airplanes in several South American countries. This would allow the C-185 to be imported as an agricultural airplane, and we suspect that the spray equipment would be removed and never used in many cases.

With the longest production runs of any Cessna airplanes, the C-180 and C-185's had many different engine power ratings and gross weights plus a wide variety of floats, amphibious floats, wheel-skis, wheel-replacement skis, spray equipment, and cargo packs. As a result.- it seemed that we were continuously conducting FAA certification tests and performance tests, preparing new owners manual supplements, and updating parts catalogs. Another task was customizing many versions of the C-185 with military equipment for the hundreds of units sent to all Parts of the world under the Military Assistance Program (MAP). These airplanes were designated as U-17A and U-17B aircraft starting in 1963 and ending in 1973. These models were powered by Continental 260, 285/300, and 230 (C-180) hp engines, respectively. All U-17's were equipped with the Geisse crosswind wheels which, no doubt, prevented many ground loops by military pilots not accustomed to "tail dragger" airplanes.

Crosswind Wheels

After John Geisse had retired as head of the CAA in 1948, he came to Cessna with his inexpensive crosswind landing gear concept. Effectively, it was castering wheels with a coil spring to bring the wheels back to the straight ahead position when the castering force was removed. A mechanical stop prevented inward castering. We built the parts to his specifications. Don Simon made the drawings and flight tested it on the 1948 C-170. It had the same type of shimmy that you frequently have with industrial and shipping carts. So Don put two round brake pucks (small) in holes in the exterior housing, and, with a spring clip, pressed them against the inner shaft which pivoted with the wheel. This corrected the shimmy problems, but it required frequent adjustment. On the other hand it was effective in reducing ground loops. However, this bulky assembly was additive to the wheel, axle, and spring gear assembly, and, therefore, it was a terrific drag producer.

At this point we started over and put the snubbing and return mechanism inside the axle, leaving only a simple external hinge-half to attach to the spring gear. This is what was installed on U-17's and some 0-I's. The USAF tested it on the 0-1 at Elgin AFB with good results. You don't often see and airplane landing ground loop with wings practically level and continue down the runway backwards without damage!

As you touch down in a crab, the downwind wheel casters outward, eliminating the fulcrum for the ground loop. In contrast, the upwind wheel doesn't caster inward because of the stop, so the tire scrubs sideways momentarily, causing a very slight downwind lurch as the other wheel deflects outward. We had the system on the first 25 U-17A's airlifted to Nha Trang, South Vietnam in July 1963. The Vietnamese were intrigued, and you would see them lying prone alongside the runway at the touchdown point to see the wheel caster. The above description illustrates the amount of development work that Cessna would perform routinely in hopes of getting a good idea to the marketplace.

Prop Noise

As the nation became more noise-conscious, we were eventually faced with external noise regulations by the FAA. Acoustical measurements were required on the ground with the airplane flying a prescribed takeoff, climb, and level flight profile and distance from the decibel meter. With takeoff performance in the C-185 at a premium we always selected the largest diameter propeller that was compatible with the "takeoff" engine rpm. This started out at 88 inches with 2700 rpm engines and finished with 86 inch diameters with 2-blade (8211 diameter with 3-blade) propellers with 2850 rpm engines. All of our testing was performed with bare interiors, and those deafening interior noise levels and "shouting communications" between pilot and observer remain memorable. As for external noise pollution, we had hoped that our customers would pull back the rpm's in climb-outs, but that was not to be. Thus, the C-185 is perhaps the most notorious noisemaker in the general aviation fleet.

A comparison of the performance of the various versions of the C-185 equipped with 285 hp (300 hp for takeoff) IO-520-D engine and a gross weight of roughly 3350 pounds is presented below:

Description Landplane Floatplane Amphibian
Takeoff ground run, ft 770 1,105 670/885*
Rate-of-climb at SL, ft/min 1,010 960 970
Service ceiling, ft 17,150 16,400 15,300
Top speed at SL, mph 178 162 156
Cruise speed @ 75% power & 7,500 ft 169 156 149
Range @ 75% power std fuel, miles 660 580 555
Range @ 75% power, 78 gal, miles 830 765 735
Stall speed, flaps down, mph 56 60 58
Landing run, ft 480 640 780/600*
*On water

The installation of a cargo pack on the landplane produced cruise speed penalties ranging from 7 mph at 75% power to 9 mph at 45-55% power. In addition, the penalty in rate of climb was approximately 40 ft/min. Level flight performance numbers for the skiplane were a 157 mph top speed, 153 mph cruise speed, 570,/750 mile range and a 56 mph stall speed. Production of C-185's in the 23 years between 1961 and 1984 was 4,427 units. The peak production year was 1976 at 297 units, and the lowest occurred in 1984 with only 9 units. Corresponding production quantities for the C-180 were 6,207 units from 1953 through 1981 (28 years). Peak production of 891 units occurred in 1955, and the lowest production of 36 units occurred in 1981. Thus the total C-180/185 production was 10,634 units including all military versions. Some of the people involved in these later C-180/185 model years were project engineers Jack Sattler, Paul Parker, Bill Bergman, Jerry Jeffries, and Glen Fickle and project test pilots Bob Crawshaw, Bob Stephens, Lynn Ikerd, Paul Leckman, Jerry Baker, Dick Kemper, Bruce Barrett and Bill Robinson among others. Assisting them were flight test observers/ aerodynamicists Joe Latas, George Alther, Larry Lay, Tom Palmer, Doug Bassett (later a test pilot) to name a few. As we watch these airplanes in continued worldwide service, it is gratifying to realize that we all had a small part in developing a true classic that has withstood the test of time. As for durability, it is heartening to realize that many of these airplanes are older than the pilots who are flying them. Judging from the amazing condition of the airplanes attending the many fly-ins of the International 180/185 Club, it appears that they may still be in flying condition when the "third generation" pilots take the pilot seat.