Cessna 175 Skylark. The Cessna 175 is a light four-seat, single-engine, fixed wing aircraft produced by Cessna between 1958 and 1962. A deluxe model known as the Skylark was introduced in 1959 for the 1960 model year. The aircraft is similar to the popular Cessna 172 but has higher gross weight and a more powerful engine with a geared reduction drive. 

Declining sales stemming from reputedly poor engine reliability prompted Cessna to drop the 175 and Skylark nameplates, but the company continued to produce aircraft based on the 175 for several decades, selling them as variants of the 172 and as a military trainer aircraft, the T-41 Mescalero.

The Cessna 175 is nearly identical on the exterior to the Cessna 172, and used the same engine as on early versions of the model, however that engine had a higher output, and by using the gear reducer, it achieved higher performance. The Cessna 175 sat in between the Cessna 172 and larger Cessna 182 in the product line at its debut.

Production history
The 175 was designed to fill a niche between the Cessna 172 and the slightly heavier, larger and faster Cessna 182. The engine of the 175, a reduction drive or geared version of the O-300 (Continental GO-300) used in the 172, is rated at 175 hp (130 kW), or 30 hp (22 kW) more than the engine offered in the contemporary 172. Between 1958 and 1962, a total of 2,106 were built. The basic airplane was marketed as the 175, and the plane with a package of optional equipment and overall paint (a partial paint scheme was used on the basic model) was marketed as the Skylark.

Design

The airframe of the 175 is all metal, constructed of aluminum alloy. The fuselage is a semi-monocoque structure, with exterior skin sheets riveted to formers and longerons. The strut-braced high wings are constructed of exterior skins riveted to spars and ribs. The 175 has fixed landing gear in a tricycle arrangement, with main gear legs made of spring steel, and a steerable nosewheel connected through an oleo strut for shock absorption.

While it incorporates airframe changes to accommodate an increased gross weight, the 175 is similar in appearance to the 172 of the same vintage. The main design change was the introduction of a stepped firewall in the 175, allowing the use of a longer cowl with larger air intakes, increasing airflow for improved engine cooling. The firewall was mounted further back in the fuselage than in the 172, and Cessna in turn relocated the instrument panel rearward into a wider section of the fuselage, allowing it to be enlarged and laid out differently than the 172 instrument panel. With the 1960 introduction of the 175A, Cessna introduced a swept-back vertical fin shared with the 172, along with a distinct engine cowling hump that serves as the most distinct external 175 spotting feature. Cessna also fitted the 175's stepped firewall and enlarged, relocated instrument panel to the 172 starting with the 172B model. 

The other significant internal change from the 172 is a structural redesign of the inner third of the wings, allowing the installation of larger fuel tanks that hold  versus  in the 172; however, due to the location of the fuel pickups, only 42 gallons is usable in all flight conditions, and Cessna advised that only  may be available at the 175's best angle of climb.

Although externally near-identical to the 172 with most parts aft of the firewall being interchangeable, the 175 was built to a different type certificate. The P172D and R172 series (including the T-41B/C/D Mescalero) share the 175 type certificate, along with the 172RG, the retractable landing gear version of the 172.

The GO-300 engine
An unusual feature of the 175 is the geared GO-300 engine. Whereas most single-engine airplanes use direct drive, this engine drives the propeller through a reduction drive, so the engine runs at 3200 rpm to turn the propeller at 2400 rpm (4:3). The GO-300 engine suffered reliability problems and helped give the 175 a poor reputation. Some Skylarks flying today have been converted to larger-displacement direct-drive engines though almost 90% still retain the GO-300.

The GO-300's tainted reputation is largely undeserved, since its problems were the result of pilots who were unfamiliar with gear reduction engines, simply not operating the engine at the higher RPMs specified in the C-175 Pilot's Operating Handbook (POH). Pilots unfamiliar with the engine often operate the engine at the low RPM settings (2300–2700) appropriate to direct-drive engines, while the 175's Operating Handbook calls for cruising at 2900 RPM. The low RPM causes harmonic vibration in the reduction gear between the quill shaft (that turned the propeller) and crankshaft, and the low power results in low airspeeds that prevents the engine's air-cooling system from operating effectively, resulting in chronic reliability problems for engines not operated at the recommended power settings. Additionally, at 2500 RPM and below, the engine does not generate sufficient oil pressure for adequate lubrication and cooling. Provisions in the original POH may have contributed to pilot confusion and improper engine operation, as the POH lists cruise speed and fuel burn down to 2400 RPM or 36% power, creating the misleading impression that sustained operation at this RPM setting is safe. Pilots of the 175 are also advised to descend gradually at constant power settings and to always keep a load on the engine, as the reduction drive makes it possible for airflow through the propeller to drive the engine at idle, which can result in engine damage.

Variants

Cessna has historically used model years similar to U.S. auto manufacturers, with sales of new models typically starting a few months prior to the actual calendar year.

175
Introduced for the 1958 model year with a geared  Continental GO-300-A or -300-C engine with a shock-mounted cowling.  Other differences from the 172 include a one-piece "Sight-Sweep" windshield and a gross weight of .  Standard equipment included adjustable front seats, electric gauges, panel-mounted fuel drain control, safety-designed control wheels, and stainless steel mufflers.  Optional wheel fairings were also available.  The 1959 model year introduced new control wheels and was available in seven paint schemes (up from four in 1958), but was otherwise identical to the previous model year.  Certified 14 January 1958.  702 (1958) and 536 (1959) built.
175A
1960 model year with a redesigned swept tail, a  Continental GO-300-A, -300-C, or -300-D engine, an external baggage door, and reduced nose geat oleo strut travel.  This model was approved for seaplane operations with a gross weight of .  A deluxe model was introduced under the name Slylark with a higher empty weight, full exterior paint, a refined interior, and wheel fairings as standard.  Certified 28 August 1959.  540 built.
175B
1961 model year with an electric starter, a "Blend-Temp" ventilation system, "Polycloud" seat lining, and optional reclining front seats.  The deluxe Skylark also featured an engine-driven vacuum system for the gyroscopic flight instruments.  Like the 175A, the 175B was approved for seaplane operations.  Certified 14 June 1960.  225 built.
175C Skylark
1962 model year with a  Continental GO-300-A or -300-E engine, new wingtip fairings with position lights, a revised cowling with cowl flaps, a dual-beam landing/taxi light on the left wing, a new two-bladed constant-speed propeller, and gross weight increased to .  The baseline model was dropped for this model year, therefore all 175Cs carried the "Skylark" name.  Certified 18 September 1961.  117 built.  This was the last model to carry the model number 175, though future variants of the same type certificate were marketed as variants of the Cessna 172.

Specifications (Cessna 175C)

See also
Skylark (disambiguation)

References

External links

175
High-wing aircraft
Single-engined tractor aircraft
1950s United States civil utility aircraft
Aircraft first flown in 1958
Aircraft with fixed tricycle landing gear
Single-engined piston aircraft