After completing their US Army contract, Sanborn and Istel dissolved JI & Co. and incorporated Parachutes Incorporated in 1958.  They opened the first PI DZ at Sebastian "Batch" Pond's  Hill Farm in XXX CT.  The first aircraft was Batch's Cessna 170B with a Fulton Conversion.  The company prospered and acquired a Cessna 182 for the New England DZ's and later acquired a pair of Cessna 180's Orange and Lakewood to relieve the demands by experienced jumpers on the Norseman.  In the final years PI also had a Cessna 195 and a 205.

Working on it

The Norseman could get to 5500' for a 20 second delay in 7 minutes from take off and make money but higher than that the profit margin started to fall.  Except on days where the winds were too high for students, few loads went right to 5500 or 7200 feet so the economics were difficult to figure but higher than 7200' was definitely a problem.  On a direct run from take-off to 12,500' the Norseman took almost a half an hour with a full load or 28 minutes with a light load to 15,000' though the company never sold tickets to that altitude.

As PI trained more people it found itself with more and more experienced jumpers.  After finishing our training we became aerial advertising for the next batch of students and good shows for the Wuffs on target tours.  BUT we were under the expected profit margin. 

PI had tried several cost cutting measures.  An example was in winter 1963/4 PI started to use weather balloons and a transit to determine the spot and save aircraft and fuel time.  I first saw Pete Guifoyle use the system.  A balloon was filled to a specific volume, specifically so that it would raise at the same rate as a canopy or streamer descended.  The balloon was watched through the transit cross-hairs and a second person called the time at 2.5 minutes.  The markings at the 2.5 minute mark were translated into a grid  reference on a piece of clear plastic taped over a 24x24 inch aerial photo of the airport posted on a wall.  The jumpmasters of any load just looked at the photo and knew the spot.

This was only partially successful and the company needed another aircraft to economically cater to the jumpers who needed to go above 5500' and it chose the Cessna 180 with the Snohomish pop-up door for Orange and Lakewood.  A Cessna 180 had been previously used successfully at Hemet, CA., piloted by Major "Bucky" Walters but it's unknown at this point if PI owned or leased the aircraft.  It came to light accidently while researching data on the first double baton pass with a woman which was done at Hemet and PI manager Lew Sanborn.  The other two jumpers were Sherri Buck and Bob McDonnell.  They used the 180 for the record setting jump.  Lew also made his 500th jump from this aircraft at Hemet.

I first jumped the PI Cessna 180 (my first 180 jumper ever) at Lakewood on July 10, 1966 while on my way to Viet Nam.  I had been jumping the Norseman most of the day doing crude rel-work with some success but they needed to fill it with students for the rest of the afternoon.  Basically 9 of us got exclusive use of the 180 for the rest of the day.  The smaller door made exits difficult (compared to the Norseman) and tight exits from small planes had not been perfected yet.  Our jumps from 7200' were less than successful.  I didn't jump the PI 180 again till July and Aug. of 1967 (I'd been in Viet Nam) but during that time exits had been worked out that made the 180 much more fun and my log book has very positive remarks about the 180 jumps.

The aircraft were in the PI Blue paint scheme with the PI logo on the tail.  No Cessna 180's were involved in any mishaps.

Background

The 180 is also approved for the Alcor "Cargomore" utility door as well as the Snohomish Pop-Up door.  The latter made a remarkable difference in (jumping) operational safety as well as Pilot/jumper comfort in cold weather.  It also cut down on parasitic drag caused by the missing door removed for jumping) and allowed the AC to get from sea level to 20,000 feet in about 45 minutes.

Utilizing the same wing as the model 170B (a NACA 2412 series airfoil section which used a single extruded aluminum front strut and included the slotted fowler type flaps originally designed for the model 305) the model 180 had a new semi-monocoque fuselage with a taller more square tail profile. 

Large single-slotted Fowler type "Para-Lift" flaps are used on all models. They increase the size of the wing as well as the camber. At half-flaps, excellent lift is obtained and at full 40 degrees of flaps, a very high rate of sink is possible. An
experienced pilot can easily land a fully loaded 180 on a football field.  This was especially useful for operating out of small drop zones or even for making forced landings in the more wooded Eastern USA DZ's.   The flaps are operated by a single manual lever and maximum flap lowering speed is 100 mph on all models up to 1964. The 1964 – 1975 models allow 110 mph. Maximum flap lowering speed and the 1976 and later models allow 120 knots for flaps at 10 degrees and 90 knots or lower for 20-40 degrees flaps.

The main landing gear, which is fabricated from chrome-vanadium spring steel, is probably the most forgiving and maintenance-free in the industry. The tail wheel features a tubular steel spring with a steerable and full swiveling pneumatic tire and wheel.  Considering how many drop zones in the 50's, thru 80's operated from "unimproved" fields, the 180 was perfect for the job.

With a 225hp O-470-A flat six engine, the new model was considerably more powerful than the model 170. Deliveries began in Feb. 1953, and rather than the business market originally envisaged, the 180 proved very popular as a bush aircraft.

Development of the 180A appeared with a O-470-R 230hp engine and B models incorporated minor changes. The 180C appeared in 1960 and incorporated a new rear bulkhead. The 1961 180D was not substantially different, but the E (1962) and F (1963) models featured changes to the fuel system. The 1964 180G had extra windows and in 1966 the seating of the G was increased from four to six. Like many Cessna aircraft, the 180 was sold as a basic model, and deluxe version - the Skywagon II with factory installed avionics.  The 180H could also carry an external  POD with an extra 3000 pounds of cargo.  Production ceased in 1981 and was one of Cessna's best seller with 6210 units being sold.

Though many newer jumpers see the Cessna 206 as the mainstay single engine jump plane, most of the older jumpers see the Cessna 180/185 complimented by the Beechcraft Model 18 (twin) as the back bone of the air fleet that made jumping what it is today. 

Length 25 ft. 6 in.
Height 7 ft. 6 in.
Wing Span 36 ft.
Wing Area 175 sq. ft.
Landing Speed About 55 mph for all models 1953 on.

Cessna produced a total of  6,193 Model 180's, the last 180 completed (SN - 18053203) rolled off the production line September 10, 1981.   Both PI 180s were produced during the first quarter of 1954.
 

You might also want to check out 
http://www.skywagons.com/index.html
http://www.skywagons.com/modelchgsweb.html
as a source for 180/182/185 information.