Differences between A and B models

How to keep the Cessna 170 flying and airworthy.

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Buckeyejim
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Joined: Sun Mar 11, 2018 9:41 pm

Differences between A and B models

Post by Buckeyejim »

I'm sure this has been addressed somewhere on the site, but I had no
luck finding it with the search function. If somebody could show me
where to find a listing of all the differences I'd appreciate it.
Metal Master
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Joined: Thu Dec 02, 2004 1:52 am

Re: Differences between A and B models

Post by Metal Master »

Edited from WIKI article
170[edit]
In late 1948 Cessna began sales of the 170, with a metal fuselage and tail and fabric-covered constant-chord wings. These earliest 170s were four-seat versions of the popular 140 with a more powerful 145 hp (108 kW) Continental C145-2 and larger fuel tanks. Like the 140, they were constructed of metal with fabric-covered wings supported by a "V" strut.
170A[edit]
In 1949 Cessna began marketing the 170A, an all-metal 170 with zero-dihedral wing tapered outboard of the slightly-enlarged plain flaps, and a single strut replacing the "V" strut of the 170. This and subsequent versions of the 170 shared the fin/rudder shape of the larger Cessna 190 and 195 models. The flap system is pull down system that uses a single cable attached to the flap handle going through pulleys’ clear to the back of the cabin and up to the overhead. The cables then are split into a Y that then operate through a bracket system and up latch at the inboard end of the flap. The flaps are hinged at the bottom rear of the wing and spring loaded to the up position. Springs are attached to the spar of the flap mid span and the forward end of the spring is attached at the rear spar passing through a cut out in the wing aux spar just forward of the flaps. The aileron control system also passes through the same pulley brackets at the rear top and the bottom of the cabin and are then routed through a tunnel in the top rear of the cabin where they pass through pulleys’ and then route out to the ailerons in the wing. The 170A with a C-145 or O-300 has a box cowl inside of the aerodynamic “sic” engine cowl. The original main gear is tapered both fore and aft and is interchangeable left or right. The tail wheel bracket is squared off at the forward end and is prone to cracking in the radius where it wraps around the rear bulkhead in the fuselage.
170B[edit]
In 1952, the Cessna 170B was introduced, featuring a new wing tapered outboard of the flaps, incorporating dihedral similar to the military version. (This taper is the same as the 170A) the twist in the wing outboard of the strut is supposedly 1 degree more than the 170A however I have never noted this to be true. The B model was equipped with very effective modified Fowler (slotted, rearward-traveling) wing flaps which deflect up to 40° The flaps have both a pull down cable and a pull up cable thus no return spring. Earlier versions do not have a 10⁰ degree notch of flaps. Sometimes earlier airplanes have had the 10⁰ notch added. These flaps are essentially the same as the later model Cessna 172. A wing design that lives on in the Cessna light singles of today (constant NACA 2412 section with a chord of 64 inches (1,600 mm) from centerline to 100 inches (2,500 mm) (the outboard end of the flaps), then tapering to 44-inch (1,100 mm) NACA 2412 section chord at 208 inches from centerline, with three-degree washout across the tapered section). Early model 170B also had a box cowl similar to the 170A. Later models did away with the internal box cowl and used what is called a pressure cowl. It is easy to tell the airplanes that have the box cowl as the have the grills over the inlets on either side of the spinner. Unless they are broken out which I have also seen. The 170B model also included a new tailplane, which is not interchangeable with the 170A stabilizer, elevators, fin or rudder. It has revised tail wheel bracket referred to as fish mouthed, which is often retro fitted to earlier models of the 170 and 170A. And other refinements over the 170 and 170A. It was marketed in 1952. In 1955, the previously elliptical rear side windows were changed to a squarer design.
A&P, IA, New owner C170A N1208D, Have rebuilt some 50 aircraft. So many airplanes, So little time!
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lowNslow
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Re: Differences between A and B models

Post by lowNslow »

Download "The C170 Book" here. It does a pretty good job of covering the history and differences of C170s. (This link is from the TIC170A Members Only Page)
Karl
'53 170B N3158B SN:25400
ASW-20BL
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GAHorn
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Re: Differences between A and B models

Post by GAHorn »

The "Wiki" article has several comments of opinion stated as facts which are incorrect. The reference to the "military wing" (perhaps they are speaking of the L-19 which was actually developed from the 170-B...not the reverse as implied), the dihedral specification and twist spec. are erroneous approximations, not specifications. The comment about the grills are also specious.

The history of the 170 is in the 170 Book as mentioned, and also posted here in the Pilot Lounge. http://cessna170.org/forums/viewtopic.php?f=5&t=228
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
Buckeyejim
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Joined: Sun Mar 11, 2018 9:41 pm

Re: Differences between A and B models

Post by Buckeyejim »

Thanks for that link - just what I was looking for.
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