Cessna Model 336 / 337 Skymaster / O-2

1961

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Cessna Model 337

The push-pull concept, with engines driving one tractor and one pusher propeller, was adopted by Cessna in the late 1950s for a light, low cost, easy-to-fly twin, and one obvious advantage over a normal twin layout was that, in the event of an engine failure, there would be no asymmetric thrust problems.

On 28 February 1961, the prototype Cessna Model 336 Skymaster flew and FAA certification followed 15 months later, with deliveries beginning in May 1963. Powered by two 157kW Continental IO-360-A engines, the new aeroplane was a four-seater with fixed tricycle landing gear, although - alternative seating arrangements for up to six were available. However, fixed landing gear on light twins was becoming passe, and after 195 Model 336s had been built the type was replaced on the production line in early 1965 by the Model 337 Super Skymaster with retractable landing gear. Additional baggage space was available in an optional glassfibre pack with a capacity of 136kg, which could be carried beneath the fuselage.

In 1969, Reims Aviation in France began licence assembly of the Model 337, with primary structures supplied by Cessna and Continental engines built in the UK under licence by Rolls-Royce. The US and French production lines continued in parallel, the French versions being classified Reims F337. The name Milirole was applied to the basic unpressurised F337 for a short time. Since 1974 Reims have developed a special unpressurised STOL version, designated FTB337, which can be provided with a wide range of equipment to make it suitable for such duties as maritime or overland patrol and rescue. Detail improvements continued each year, and a turbocharged version, the Model 337 Turbo-System Super Skymaster, was introduced in 1970, but the prototype of a pressurised T337 Skymaster, powered by 168kW Continental TSIO-360 engines, flew in July 1971 (the word Super had then been dropped), and deliveries began the following May.

Military versions designated O-2 were supplied to the US Air Force for various missions, including forward air control, for experience in Vietnam suggested that such sorties could be made more effective with FAC aircraft operated by a pilot and Forward Air Navigator (FAN), the latter being able to concentrate on the FAC mission without having to fly the aircraft.

Cessna's Model 337 was selected 'off the shelf' in late 1966 as being ideal for this role, and equipped with four under-wing pylons to carry flares, rockets and light ordnance such as a 7.62mm Minigun pack. 501 were supplied to the USAF designated O-2A. In addition, a version equipped for psychological warfare missions entered USAF service under the designation O-2B This carried a powerful air-to-ground broadcasting system using three 600-watt amplifiers and a battery of highly directional speakers. Total procurement of O-2B aircraft amounted to 31. Both versions car-ried advanced nav/com systems. Twelve O-2As were supplied to the Imperial Iranian air force in early 1970. A twin-turboprop O-2T/O-2TT did not proceed beyond USAF evaluation.

Production of the Model 337 series by Cessna ended in mid-1980 by which time 1,821 Model 337s, 313 pressurised Model 337s and 544 military O-2s had been delivered. French production by Reims Aviation totalled 66 Model F337s, 27 F337Ps and 61 FTB337s.

Cessna O-2

Specification 
 MODELCessna Model 337
 ENGINE2 x Continental IO-360-GB flat-six piston engines, 157kW
 WEIGHTS
  Take-off weight2100 kg4630 lb
  Empty weight1264 kg2787 lb
 DIMENSIONS
  Wingspan11.63 m38 ft 2 in
  Length9.07 m30 ft 9 in
  Height2.79 m9 ft 2 in
  Wing area18.81 m2202.47 sq ft
 PERFORMANCE
  Max. speed332 km/h206 mph
  Cruise speed315 km/h196 mph
  Ceiling5485 m18000 ft
  Range2288 km1422 miles

Comments1-20 21-40 41-60
Floyd, e-mail, 22.04.2011 06:24

Great aircraft. Worked on them at Tan Son Nhut in 1972. 21st TASS

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Scott Boyd, e-mail, 19.03.2011 18:28

A guy in Denver bought one of the first P-337's when they came out. Every time he went somewhere the plane broke. I remember picking it up in Dallas, after he left it there and flying it back to Denver, by the time we got back it went right to the shop.

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E.G. HICKAM, e-mail, 19.03.2011 00:15

Air America flew mostly o-i bird, but one 0-2 and the additional rockets were welcome.but O-1 defineately better for our work there with Thais. T-28's our back seaters liked the O-2

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Amalp, e-mail, 12.02.2011 03:48

In response to Malcolm Quick's request for a lapel /tie tac pin of a 337 /0-2, contact Amalp at amalp777@hotmail.com. I'll get you internet locations for said pins.

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exctyengr, e-mail, 24.01.2011 19:13

Own and fly a P337H, my second one. Owned and flew N28UM a normally aspirated 337 for 14 years. Great airplane, honest, reasonably fast, comfortable, easy to fly with no bad traits, Downside - a bitch to work on (I'm an A&P /IA). Also quite noisy inside and out. Good headsets mandatory. I have found that none of the overheating myths are true even in the Arizona desert. Keep em flying!

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John Cummings, e-mail, 17.01.2011 20:12

I was at Utapow Air Base in 1975. Saw a big field of these while walking to the EM club.

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malcolm quick, e-mail, 13.12.2010 23:20

Flew O-2 as night FAC Bihn Thue 68-69. Flew every night. Had 10 birds that were hand-me-downs from NKP. Cesna rep gave each of us a tie tack pin of a 337 /O-2. I have lost mine. Does anyone have a clue where I might get a replacement?

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Harry Brodock, e-mail, 22.11.2010 23:51

Flew the O-2, transitioning from the O-1 in 1970. Was part of the original team set up to get the O-2s to VietNam. Basic T /O gross wt was 4400 lbs, with 400 lbs of rockets jettisonable on takeoff. They flew 5-ship formations (civilian pilots) out of March AFB, CA, with a takeoff Gross wt of 7000 lbs (mostly fuel). Took about 10,000 foot takeoff roll. This was because ot would take too long to cuccoon them, put them on ships, and de-cuccoon them in Nam. If they lost an engine after 6 hours, they could still make it single-engine. The first leg was from March to Hickam AFB, Hawaii (24 hours at 100 knots). Then from Hickam to Johnston, Johnston to Wake, Wake to Guam, Guam to Clark (Phillipines), and on to Bien Hoa, VietNam. 365 each O-2s in 5 ship formations, with c-130 motherships overseeing them. All without a loss.
Have over 200 mission in the bird, and only took 3 ground-fire hits. Good thing for self-sealing tanks.

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Guillo Ambrogini, e-mail, 17.11.2010 17:26

During my earliest operations in Patagonia Argentina, from grave airfields I had big problems with stones, my new airscrews (specially nose airscrew) became a saw!
To avoid this I used for to take off the following operation way:
Flaps in first position.
Brakes on.
Mixture according to airfield level.
Airscrews high RPM (pitch).
Front engine idle .
Rear engine full throttle.
Command all back.
Brake off.
In few feet the nose is up.
Full throttle to front engine.
In some hundreds feet up flying normally.
And never more stones touch my airscrews!

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Guillo Ambrogini, e-mail, 16.11.2010 19:56

I had a C-337B during few years until it was crashed by negligent pilot.
My operations were in Patagonia, south of Argentina, next to Andes range.
It's a region with mountains, lakes and glaciers.
My landing field had 2,000 ft, gravel and often with cross wind (20-25MPH).
The average flights had 2-3 hours but several times reach 5-6 hours and the flight level was 15,000 ft.
Often, for long duration flights I flew with the nose engine cut and the aircraft behavior was excellent, without vicious, its maneuverability was normal and quieter than with both engines.
Because in Patagonia there aren't not much airfields a normal practices was take off and landings on roads, dry streams or field.
The landing gear is extraordinarily strong and resistant.
The C-337 has an incredible maneuverability, the commands are light and the response time is instantaneous.
I love this airplane!!!

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Chuck Galbach, e-mail, 30.10.2010 15:13

I flew the O-2 (and O-1) at Danang, 67-68, as a FAC and 20th TASS test pilot. I didn't care for it for FAC'ing, though with 2 engines, it was likely safer than the O-1. It was much faster than an O-1 if you had to get somewhere in a hurry and had much better range. Generally reliable. A few single engine returns from test hops, plus one complete electrical failure (aluminum battery buss cable burned out) with uneventful landing at Danang. We replaced all the cables with copper and had no more trouble with that. Noisy airplane - couldn't hear ground fire, resulting in usually no evasive action and a few holes in airplane (never was hit in an O-1 though, even though I had more FAC missions in it). Good airplane for going somewhere - a little less good for FAC missions (small rudders, yoke instead of stick, thus less maneuverable, shallow angle of climb though good rate of climb, couldn't go into little dirt strips, etc) - though I did like all those extra rockets. Usually fun to fly in spite of my dislikes.

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Bob Leonard, e-mail, 27.10.2010 09:20

I flew the C-337 in the Caribbean area and found it to be a straight forward honest aircraft. If you loose an engine, pick the front one because it flew SE on the rear engine much better. I found it to be noisy inside, between those two engines. All in all, an interesting aircraft design.

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Ken Orton, e-mail, 20.10.2010 02:17

Flew many missions out of NKP in this aircraft with a right seater with a starlight scope. Never had to abandon the four hour mission but the word was that if you lost the rear engine on T /O you were toast. Day missions were dicey as it wasn't real maneuverable but would well exceed the top speed in a dive without problems.

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yaron, e-mail, 10.05.2010 06:52

James D. Lyne,

Hello
can you send me an e-mail, interested in talking to you.
about redoing few 337's .

thank you
yaron

i have been flying 337 for the last 20 years

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Chuck Banks, e-mail, 29.03.2010 21:41

I find several web sites that have similar performance numbers for the O-2. Those must be for the 235HP, Turocharged, Presurized 337. In 600 hours of flying the O-2, I only found one that could cruise faster than 128 knots. That one was painted with slick paint and could do 132. Also, cruise = max. Carrying rocket pods slowed them to 125 or less. Ceiling was 10,000 feet, since it was unpresurized with no oxygen. With max fuel, you could fly for 5 hours, which made the range a little over 600NM with no reserve. Max gross was 4,800 lbs, but 400 of that had to be hanging on the wing hardpoints. Also, a third seat could be installed in a couple of minutes. Great plane for the FAC role! Also, I met my wife by taking her for a ride in one when she was a ROTC cadet.

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Scott Boyd, e-mail, 24.02.2010 00:27

I remember Riley, from the time we needed a fuel pump for the Turbine Eagle. There were fuel pumps all over the place at least 4-6, Riley owned sole rights and charged accordingly.

Nice aircraft if you could afford to fix the tail frequently.

Too bad the 425 didn't have the -135 engines

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James D. Lyne, e-mail, 20.02.2010 19:54

I worked as Production Manager and later as Chief of Flight Test for Riley International and it's subsequent iteration, Riley SuperSkyrocket from the late '80s until 2002. We modified the pressurized P-337-G and H, primarily with the addition of intercoolers, pressurized magnetos, STOL kits, electric doorseals, airconditioning and modern avionics, a poofy interior and paint jobs. Mine stalled at 42 KIAS, would get in and out of 1500' easily and cruised at 210KTAS at 20,000' on 25 GPH. A great performing airplane that I, as an A&P, would not work on myself. Cost too much, due to lost Snap On tools, thrown out of frustration. Our later effort installed TSIO-520-NB engines off of a C-414, a great two-place airplane that climbed at 3,500 FPM, 1500 on one. Cruised at about 245 KTAS on 36 GPH, but you could pull it back to the same fuel burn and speed of the "little motor" Skyrocket. Of course, why would you pay $595,000 (in 1991) just to do that? I used to demonstrate single-engine takeoffs (the other idling) in the "Skymonster" and it performed about like a P-210. 5000' AGL on downwind, abeam out of CRQ was a real crowd pleaser too. AS Jack Riley used to say: "When you've got that much horsepower (620 HP at 4700 lbs GW) it's hard not to be just a little bit of a smartass". It was, indeed.

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Joseph Acampora, e-mail, 17.02.2010 19:59

We obtained the O2's from Nam when they were replaced with the OV-10 Broncos. Sent to Osan,AB in Korea during 1970, I was taught how to fly one by my FAC officer after completing the pre-flights with him too many times to mention. We used the Snoopy,Linus,Charlie Brown call sign designations. Had a ball controlling ROK Air Force F-86 Super Sabres in OD paint with sidewinders. Also worked countless USAF F-4s from Japan. Would like to contact anyone who was in my squadron. (603rd Direct Air Support)

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Michael Richter, e-mail, 02.02.2010 22:57

Hey guys, does anyone can tell me which aircraft do you think is a good replacement for the O2A Skymaster?? I need at least three names, hopefully similar characteristics. Thanks!!!

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Walter W. Want, e-mail, 08.01.2010 22:28

If you want the real thing, go to the FAC Museum at Mechem Field, Fort Worth, TX or check out: WWW.FACNET@yahoo.com or the OV-10 Bronco Assn at the same location.

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