skymaster history

8/4/2019 Skymaster History

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History of the SkymasterThis started as a posting from gmas from the 337 Club on the Message Board. Dave Zavoina and

myself have added information. This is no where near complete and any further informationwould be most welcome to [email protected]

The first prototype Skymaster was a basic 4-seat, all-metal, high wing push-pull twin aircraft.The tricycle undercarriage was fixed and had two 175hp Continental GO-300-C geared engines.The prototype was registered N34273 and was given the construction number of 633 (CessnaExperimental Series) and first flew on 28 February 1961. It wasn't until August 1962 that thefirst production aircraft flew and mid-1963 before deliveries began. Production models of the336 were different from the prototype by having IO-360 engines, an enlarged cabin to take 6people, inboard wing sections were redesigned and the vertical tail surfaces were enlarged.TOGW was 3,900lbs. 195 production 336's were built and were given construction numbers of336-0001 to 336-0195.On 30th March 1964 the prototype of the 337 first flew, piloted by Dick Kember. Despite itlooks being similar to the 336 it was a largely redesigned aircraft. The wing incidence angle wasincreased, the nose cowling was redesigned, the tail boom angle increased, a new dorsal airintake for the rear engine was added and the 337 had retractable undercarriage. This was the firstmodel called the Super Skymaster. The word Super was dropped in 1972. The prototype wasregistered N5422E and had the construction number of 647. Production on the 337 started inFebruary 1965. This model has a TOGW of 4200lbs and IO-360C engines. The cost of a new337 would be around $39,950. A new construction number series was started for the 337. Thesebasic models had construction numbers between 337-0001 and 337-0239.In 1965, the USAF at Eglin AFB, FL, modified a 336 with four sets of hard points on the wings,and had a one time STC approved by the FAA. The serial number on that plane is 336-0026. Itwas used a proof of concept to see if the idea was feasable for the 337's to be used as FAC

aircraft. The Cessna model 305's (Birdogs) were getting hammered in South East Asia and NorthAmerican Aviation Bronco's were late in getting into production, so the Air Force wasscrambling to find a stop gap aircraft that had the range, load carrying and had multienginereliability to supersede the birdogs. This 336 eventually became N331KW. At one time it wasowned by a Belize national who is now living in the USA. He repainted the aircraft in falseBelize Air Force markings and pained on a false registration of V3-1KW. Someone from theBritish magazine 'Airforces Monthly' saw this aircraft and it was announced in the magazine thatthe Belize Air Force had an ex-USAF O-2! Even today there is a mention of this aircraft underthe Belize Air Force heading in 'Air Forces of the World' and other military reference guides,despite the fact that he has now sold the aircraft and it is now back carrying its true identity (ieN331KW).

In 1966 the 337A was produced. This had minor changes to the standard 337 and constructionnumbers in the range 337-0240 and 337-0525. There were 286 of them built.1967 saw the 337B. TOGW was increased to 4,300lbs and there was an optional belly cargopack. A further option on this aircraft was a turbocharged 210hp TSIO-360-A engines. The pricefor a T337B in 1967 was $49,500. Construction numbers for the 337B and T337B went from337-0526 to 337-0755 and there were 230 of them built.1967 also saw the building of a reduced scale version of the 337. This was known as the 327.Only one aircraft was built and first flew on 4 December 1967. It was registered N3769C andhad a construction number of 663 (Cessna Experimental Series). This aircraft later went toNASA as a 'full scale wind tunnel research unit'.In 1967 the USAF placed an order for Skymasters. The military designation for theses aircraft

was O-2A. They had their own construction number sequence starting at M0001. The USAF alsotook 32 aircraft from the civil production lines. These retained their civil construction numbers


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and were fitted with loud-speakers and leaflet dispensers for psychological warfare duties. Theywere also different from the O-2A's by not having hard-points under the wings.The main differences between the 337 and the O-2 included the removal of the cabin step andspinners on the propellers, addition of observation windows in the cabin door and roof of thecabin. Engine fire detection equipment were added together with smoke generator equipment

added to the rear exhaust system. The instrument panels were also different and they had anarmament switches panel installed. Four underwing pylons for rockets, flares and cluster bombs.Amour plates were installed under the seats and porous foam slabs were place in the fuel tanksduring assembly to make them explosion-resister after being hit by small arms fire. This resultedin about a 5% loss in fuel capacity.The 337C came in 1968 with a new instrument panel and 4,400lb TOGW (4,500lb on T337C)Minor changes were made in 1969 to produce the 337D. Construction numbers in the range 337-0979 to 337-01193 with a total of 215 built.Cambered wing tips plus other minor changes came on the 1970 337E. T337E's has a TOGW of4,600lbs, construction numbers between 337-01194 and 337-01316 and a total of 123 built.The 337E was the first Skymaster model to be re-built in France by Reims Aviation. Reims

Aviation started life as Avions Max Holste in 1933. Due to financial stresses Cessna acquired a49% shareholding on 16th February 1960. Reims started building Cessna aircraft from kitssupplied from the USA for the European and Middle Eastern markets. Skymasters re-built byReims have both Cessna and Reims Construction numbers.The 1971/2 337F model had 4,630lbs TOGW for both non-turbo and Turbo models.Construction numbers of 337-01317 to 337-01462 were on these 146 aircraft.In 1973 the 337G emerged. This had split airstair entry door, smaller rear side windows,improved flaps, larger front propeller, modified wing struts and Cont. IO-360-G engines.Production of this model continued until 1977 by which time 353 had been built withconstruction numbers in the range 337-01463 to 337-01815.A Turbo charged version of the 337G was produced in 1974. This model also had a pressurisedcabin and redesigned windshield. A new construction number sequence was started for theseaircraft.Between 1978 and 1980 the 337H models were produced in three forms ie 337H (normal)T337H (Turbo) and P337H (Pressurised cabin). Cost for these aircraft were $124,090 for thestandard model and $140,890 for the turbo model.Production of the Skymaster by Cessna finished in 1980. However Reims Aviation of Francewas assigned world-wide marketing rights to the aircraft, and as a result they built (from scratch)a further 61 aircraft, which it called the Reims FTB337 Minirole. Most of these aircraft went tomilitary operator in Europe and Africa. The Portuguese Air Force taking the most.Even with production of the Skymaster finished that is not the end of the story. A modification to

the pressurised 337's was first undertaken by Riley. This modification consisted of adding aRiley intercooler to pump cooler air from the turbochargers into the aircraft's engines that greatlyimproved the aircraft's performance. STOL modifications to the wings, air conditioning,comprehensive avionics package, new paint scheme and a custom interior were also part of thedeal. This 'new' aircraft was dubbed the Riley Skyrocket. Riley also tried to launch the SuperSkyrocket but unfortunately, went out of business before FAA approval came forth for this newmodification. However, LLC of Carlsbad, California has now obtained the necessary approvaland is now modifying P337's. This modification consists on installing two turbocharged 310hpContinental TSIO 520 engines, with intercoolers.


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Message Board Archive

History of the SkymasterIf you have any further information concerning any on the topics mentioned below the please

don't keep it to yourself. mail me so I can share it with the world!

Differences between different models

GM 337 Club... said About the only thing I can say that is different between the two (military

and Civilian) is that the military had a extra spar cap strip placed top and bottom of the mainspar... also the fuel tanks were full of the material to stop explosions... and I guess leaks... and

some wireing and window placementDave Zavoina added As far as structural differences, the O-2A wing attach bolts are two bolt

sizes larger. As far as interchangable parts go, in the military -4 (Illustrated Parts Catalogue)

every sheetmetal part has the suffix "CP" behind it. This meant "Corrosion Proofed" and unlessyou ordered a seaplane version, you didn't get this part in your plane. Every rib, stringer, etc was

alodined and primer before assembly on the military birds, Birdogs, Skymasters, Blue Canoes,

and Tweets all had this. I don't beleive that many 337's were ordered with seaplane options. With

the exception of one T337H that I've had the pleasure of working on, have I seen the entire

interior of the wing zinc chromated. That H model was built approximatly 10 years after the last

O-2 left the assembly line. Now, I'm not trying to pick on you, but when you tell the poor slob

that he has to march down to the FAA and tell them he has the wrong wheels and brakes on his

plane, you need to validate your response with facts, not myths. The O-2A is a much diferent

creature than a 1967 B model is to a P-337 and it has its own idiocrincies that need to be

addresssed.

Manufacturing of the Skymaster

Dave Zavoina said in a mail on another topic The O-2A's were not manufactured at the same

facility as the civillian counterparts. Cessna Commercial and Cessna Military were 'friendly'

competitors and very rarely exchanged information and parts. For instance, if you contact Cessna

Aircraft for a 28v, 60a gear driven alternator for a 337, they will tell you that it doesn't exist, youwill have to get the 35a unit for a 337, but the O-2 has two of them on the early models and one

on the front on the late models. The later models have a belt driven alternator on the rear engineGM 337 Club... replied when I went through the plant many years ago... I still can remember

seeing the military birds being built side by side with the civilian ones.

Preserved O-2's

GM 337 Club... said to Dave Zavoina Would like to see your restored O-2.. always interested in

seeing the VN birds... we had one out here that was making the airshow round... but, has

disapeard. I have always wondered why...

Dave replied My plane is on display at the Lone Star Flight Museum in Galveston, TX, and is

available for viewing at any time from 10:00am to 5:00pm along with about 40 or so other

interesting aircraft.

GM 337 Club... asked further Does your plane have the kangaroo on the tail... or just the USAF...The ones over in nam had the kangroo on the tail... skull and crossbones... or USAF.. The Navy

also had some that were painted in blue and yellow... saw one when flying over the desert one

time... nice looking color ... seems they were stationed at Fallon... according to another writer onthe board... would have liked to find out what action they saw... and where they went... fly safe..

G.M>


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Dave replied Yes, the Navy had 6 O-2's at NAS Fallon with VFA-125. I picked one up at NAS

Pensacola who had purchased it from the Naval Aviation Museum. I flew that aircraft, call signDUCK 593, later registered as N593S, to Houston, TX with DUCK 594, later N594X, and

performed the Comformity Inspection and had them both issued airworthiness certificates withSan Antonio MIDO. My plane never had the Kangaroo on the tail, those were flown by the

Aussies with the 20th TASS at Da Nang. My plane was with the 23rd TASS at Nakhon PhenomRTAFB, Thailand and with the 504th at Bien Hoa AFB, Republic of Viet Nam assigned to FAC

U., a training unit for new in country FAC's.. Originally there were six Navy O-2's, the Marines

snatched two of them, and I think one of them ended up at the Marine Air and Ground Museum

in Quantico, VA. One is still in the Houston area, one that was in Houston was sold to a person

in North Carolina. I don't know what happened to the other two. There is a big Navy Criminal

Investigation Division invesigation associated with the sale of these aircraft as well as some

other aircraft deals that were allegedly not done per disposal specs. I've also heard of the

television camera installation. They had a tramsmitter that downloaded the signal to a "Spook"

trailer that had a lot of technicians in civillian clothing going in with an armed guard stationed

outside.

Types of Skymasters

Wess Daniels asked 'Was skymaster a military aircraft first?'

Jason Friesen replied The skymaster started as an attempt on the part of Cessna to design a safer

general aviation twin. The 336 was never used by the military and it wasn't until after the 337

came out that the military decided to use the faster skymaster to replace their vulnerable L19s inVietnam.

Ian Clapp added The 327 was the scaled-down version of the Skymaster designed to competewith the Twin Comanche. It first flew in December of 1967, several years after the first 336/337

flights. It was indeed a very nice looking aircraft with clean lines akin to the Cardinals's.

Unfortunately, performance and cost issues caused Cessna to drop the 327 project.Peter added According to Airlife's General Aviation Book. There was one Cessna 327 Mini

Skymaster built. It was a reduced scale version on the 337. It was registered N3769C and had a

c/n of 663 (Cessnas Experimental Series) It first flew on 4 Dec 1967 and it ended up going to

NASA as a "full scale wind tunnel research unit" The Cessna 1014 XMC was a twin-boomed

two-seat aircraft with a single puster engine. Only 1 was built registered N7174C (C/N 674) and

first flew on 22 Jan 1971. The book does have a picture of the XMC in it.


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Cessna O-2 Skymaster (Model 337)

Background

The Cessna Model 336 first flew in 1961 and went into production in 1963. The Model 337which introduced retractable undercarriage and other design changes (cowl flaps, wider chord

elevator, dorsal cooling intake) appeared in 1965. The military O-2A version was first flown in

1967, with the O-2B (psychological warfare model) and production aircraft following the same

year. The O-2 has been operated by the USAF as an observation and FAC aircraft. In 1971 apressurized version was produced, followed in 1975 by the upgraded Skymaster II.

The O-2 has not been operated by the RNZAF, but a number of RNZAF pilots flew FAC aircraftin Vietnam while on exchange to the USAF. An O-2A-CE (c/n 337M-0437), 69-7639 was

donated to the RNZAF museum to commemorate this service. The aircraft did not serve inVietnam, but was operated by the 182nd TASG (Peora AFB) and 4507th CANS (Shaw AFB)

before being placed in storage at Davis-Monthan AFB.In December 1996 I received the

following communication regarding the aircraft's path to New Zealand from Col. Ed Sheeran(USAF, ret) who kindly allowed me to reproduce it here:

" In 1988, I visited Air Commodore (then Group Capt) Graeme Goldsmith when he was

commanding officer at RNZAF Base Wigram. I was flying the C-141 on the mid-winter airdrop

to McMurdo and South Pole Station at the time.Graeme and I had flown together for a short

period in SoViet--I was his instructor in FAC ops with the O-2A and he was the patient student of

a very new IP! We both noted the lack of SEA memorabilia for the RNZAF pilots who flew as

FACs. When I returned to Norton AFB in So California, I contacted a friend at the USAF

Museum at Wright-Patterson AFB, Ohio, looking for FAC stuff. He agreed to tag an O-2A at the

boneyard at Davis-Monthan AFB for the Wigram Museum if I could work a way to get it there on

one of the weekly Starlifter flights. I got it listed on Norton's "opportune airlift" list, but then lost

track of it until Graeme called and said the O-2 had arrived at Wigram, sans tech data, decals,

stencils, etc.The restoration people have obviously compensated for that"

Ed Sheeran, Colonel, USAF (Retired)San Antonio, TexasSkymasters appearing on the New Zealand civil register (as at 1 may 1999) include ZK-DFT,

ZK-DSC (337G), ZK-FZA (T337G), ZK-KLB (337A), and ZK-TSH (T337G). Apart from the

RNZAF museum model, no other military models have reached New Zealand, although ZK-DFT

and ZK-FZA has been painted to represent an O-2A.

Last Update:-27 May, 1998

Technical Data Accomodation : 4 Dimensions

Span : 11.63m (38'2ft) Length : 9.07m (29'9ft) Height: 2.84m (9'4ft)

Weight empty : 1,475kg (3,350lb) max : 2,450kg (5,400lb)

Power Plant: 2x 210hp Continental IO-360-C Performance :

max speed: 287km/h (178mph) max climb : 935ft/min (4.75m/sec) ceiling : 15,100ft (4,600m) range : km (miles)

skymaster history

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