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| Success with the DHC-2 Beaver persuaded de Havilland Canada in the late 1940s that there was room in the STOL utility market for a larger version of the Beaver, with cabin space for some 14 passengers or a freight load of up to 1016kg. The company therefore developed the de Havilland Canada DHC-3 Otter, which was essentially a scaled-up Beaver, with an all-metal airframe and a 447kW Pratt & Whitney R.1340 Wasp radial, and which was initially known as the King Beaver. The choice of a single engine for an aircraft designed to operate in Canada's harsh climate and sparsely populated hinterland regions may seem lacking in forethought. However, successful operations by the Beaver and other single-engined types had confirmed that the well-proven radials of Pratt & Whitney design were more than adequate for the task: they were universally familiar and, more importantly, were extremely reliable.
Notable for its parallel-chord wing with double-slotted flaps for good STOL performance, the Otter is an attractive high-wing monoplane with a single bracing strut on each side. The prototype first flew on 12 December 1951, and first deliveries were made in-1952. When production ceased in 1968, some 460 had been built, including 66 for the Royal Canadian Air Force and 227 for the US armed forces (223 of the U-1A for the US Army and four of the UC-1 [changed to U-1B in 1962] for the US Navy). When released by military operators, many Otters joined those already on the civil market, where again the type had found ready acceptance for its versatility. Like the Beaver, the Otter can operate on wheel, ski, float or amphibious float landing gears.
Despite its already impressive STOL peformance, the Otter was selected as the basis for a Canadian experiment in advanced STOL characteristics, a programme undertaken by the company in conjunction with the Defense Research Board. As part of this programme an Otter was fitted with extremely large flaps inboard of the strut/wing junction points; this also necessitated an enlargement of the tail surfaces, and ground stability was ensured by the replacement of the original tailwheel landing gear with a float chassis fitted with quadricycle wheels instead of the floats. The STOL modifications reduced the Otter's stalling speed by some 16km/h. The flaps were then removed, and a 1112kg thrust General Electric J85-GE-7 turbojet installed, in the fuselage aft of the wings, with adjustable nozzles protruding one through each side of the fuselage. This arrangement permitted far greater control of speed, and allowed spot landings. Finally, the single Wasp radial was replaced by a pair of wing-mounted Pratt & Whitney Aircraft of Canada PT6 turboprops, whose slipstream was found beneficial to the controllability of the aircraft.
Under the designation DHC-3-T Turbo-Otter, one aircraft has been modified by Cox Air Resources to turboprop power, a 494kW PT6A-27 replacing the standard Wasp. Empty weight is thus reduced to 1861kg, resulting in a useful payload increment.
Airtech Canada of Peterborough, Ontario, has recently converted a number of Otters to take either the 447kW PZL-3S or 746kW Kalisz ASz-621R nine-cylinder air-cooled radial engines manufactured in Poland, each driving a PZL four-bladed constant speed propeller. The re-engined aircraft offer increased climb rates and greater fuel economy at lower power settings. The first PZL-3S conversion flew in August 1983.
 | A three-view drawing (1000 x 659) |
| ENGINE | 1 x Pratt & Whitney R-1340-S1H1-G Wasp radial piston engine, 447kW |
| WEIGHTS |
| Take-off weight | 3629 kg | 8001 lb |
| Empty weight | 2010 kg | 4431 lb |
| DIMENSIONS |
| Wingspan | 17.68 m | 58 ft 0 in |
| Length | 12.75 m | 42 ft 10 in |
| Height | 3.84 m | 13 ft 7 in |
| Wing area | 34.84 m2 | 375.01 sq ft |
| PERFORMANCE |
| Max. speed | 246 km/h | 153 mph |
| Cruise speed | 195 km/h | 121 mph |
| Ceiling | 5485 m | 18000 ft |
| Range w/max payload | 1408 km | 875 miles |
| Jack Frost, e-mail, 17.07.2014 01:11 Introduced to the Otter whilst serving as an RAF fitter at Woomera 59 /62. Took delivery of the a /c and enjoyed a few tourist familiarsation flights out of Bankstown and up the east coast. Off to Woomera creating a long distance gliding record for an Otter when the engine gave out with a bang and clatter over Victoria. Removed the engine and took it back to Bankstown in the back of a VW pick up!Eventually enjoyed many trips in the outback from Woomera. reply | | Brian Hall, e-mail, 26.06.2014 05:53 I spent the summer of 1958 at Cold Lake AB as a F /C with Navigator's wings, and had the good fortune to spend a large part of the time flying around the Northwest Territories in a float equipped Otter (VR661) with Mac Willard as pilot. We were visiting all the Ground Observer Corps stations, and the Otter was absolutely the best aircraft for the job. Of course, the fact that Mac was an ex bush pilot from BC made it look easy. There were many of the small lakes that required taxiing at speed in circles to create enough waves so we could take off. reply | | larry patch, e-mail, 13.06.2013 05:16 1 yr in VN...54th Aviation Co..Otter was best flying assignment ever...very safe for us non-hero types reply | | larry patch, e-mail, 13.06.2013 05:15 1 yr in VN...54th Aviation Co..Otter was best flying assignment ever...very safe for us non-hero types reply | |
| | McCan, e-mail, 29.04.2013 00:05 When were you there? I was XO of "Big Daddy" in 1970. We flew out of Log Than North. I even flew "Fat Albert" when she wasn't in the hanger!
Raymond Beauregard, rpbst=comcast.net, 16.02.2013
Flew the Otter in RVN, 54th Airplane Co. Great airplane, slow, low and reliable. reply | | Raymond Beauregard, e-mail, 16.02.2013 19:33 Flew the Otter in RVN, 54th Airplane Co. Great airplane, slow, low and reliable. reply | | Ben LaVigne, e-mail, 13.02.2013 06:06 All you people with comments about the otter are NOT true!! If you left a comment here and think your an otter pilot and have something neg to say even if its against the standard otter, you simply havnt flown this incredible airplane enouph. Its all inexperience and no respect. My father has been operating this airplane for 40 years and no accidents.It comes down to pilots and there capibilites.
He has also flown this plane with me in it, for thousands of hour and NO accidents. I guess these pilots today are really FAKE. Except a Few Like John Kaartinen!!! Any comments, you fake otter pilots, PLEASE EMAIL me @ dehavilandhxy@gmail.com reply | | Norman Dack, e-mail, 17.09.2012 21:50 I was in the RCAF stationed in Cold Lake, Alberta in 1955 and 1956 and used to fly in the Otter back and forth to Primrose Lake to the Velvet Glove missile range. I was told this aircraft could take off in the width of the runway, not sure if that is true. I know they could land on water, ice, or land. reply | | Roberto Mendieta, e-mail, 16.06.2012 02:33 We had a couple of them in the Nicaraguan Air Force back in 1977, great planes!!!!!!! reply | | mike, e-mail, 08.05.2012 18:47 I made a jump from a Army UA-1 in Thailand in 1969 with the 46th SFCA. The plane would hold about 8 paratroopers. I am interested in building a 1 /6th scale RC model. If anyone knows where I can get plans please let me know. reply | | Roy Hannah, e-mail, 11.04.2012 19:07 I was a crew chief on the U1A in the 12th Av. Co. Ft. Sill -1958 /60. My brother, Jerry, was also a crew chief. Flew all over the U.S. Great plane. We lost one plane in 2 1 /2 yrs. Blown jug , Accident on landing at night. Anyone remember us? reply | | Bob Anderson, e-mail, 18.08.2011 01:57 IN the mid 1950's I ferried many of these from Toronto to Mobile AL for shipment to Europe for the U.S. Army. Also had Army friends that were killed in Demo flight Toronto 195? when flaps suddenly retracted from full at slow flight and A /C rolled on back and wings folded. Still one of the best A /C I have ever flown. reply | | ROGER FETZER, e-mail, 19.07.2011 09:27 1966-67 18th av. co.--256th trans det. I engine mechanic for the otter--stationed at Qui-Nhon. Changed out a lot of r-1340's --great sounding engine. If you were there, like to hear from you. rkf /out. reply | | luson, 20.06.2011 13:58 Carried so much fuel when topped off that it was also used for loitering on station as a radio relay. It was limited by consistently high oil consumption. reply | |
| | David Darbyshire, e-mail, 25.01.2011 15:59 I learned more about flying while piloting the Otter in Nam, than in any other plane in my 40 year flying career. Great airplane. reply | | Bill, e-mail, 11.01.2011 05:40 John
I believe the PWC conversion you mentioned in your note was done by Kenmore Air Harbor. Kenmore Washington. They have several STC's for Turbin's in Beaver's and Otter's reply | | John, 03.01.2011 03:28 From my previous post:
" ... The radials can overfly mountain ranges with pilot + passenger oxygen well above FL12, something the radials have serous issues with. ..."
Should read:
" ... The turbos can overfly mountain ranges ... something the radials have serious issues with ..." reply | | John, 03.01.2011 03:24 Working in the far north for many years, I probably have made roughly 3000 flights in single Otters, all on floats. I've flown in the PW Radial, the PZL Radial (which we called "the Polish Otter"), and three versions of turbo conversions: the original turbo mentioned in the article, the PWC conversions done in Washington State (don't know the company) and a Walter turbo conversion. The PZL radial, at 1000 HP vs the PW radial at 600 HP, is similar to turbo performance. The turbos are of course superior, not the least of which is the 3000+ hour TBO vs 800 for the PW Radial, but also in performance, in particular climb. The radials can overfly mountain ranges with pilot + passenger oxygen well above FL12, something the radials have serous issues with.
The plane is also very crash-worthy ... and the four incidents I know of crashing in bush resulted in no injuries or deaths. I can't say that for the Cessena 185, DC-3 and various helicopter crashes I've witnessed or was on search parties for. For search, the Otter is outstanding; you can put one wing down pointing essentially at a single point on the ground and circle all day if you want, or do the usual patterns with excellent visibility in every window. These aircraft are invaluable ... you can't dock Twin Otters safely or practically at an ordinary dock, unless making firewood is your goal, nor are open-water pickups nearly as safe with both engines running (typical need in rough weather).
Outstanding aircraft, unbelievably rugged cargo ability, and there is no practical replacement anywhere ... the Russians have a single engine biplane with similar STOL and Bush performance but the docking issue exists with the lower wing. Cessena Caravans look good on paper but need a mile for water takeoff and are nowhere near as tough. They will be running well into the 21st Century; there is no alternative on the market to do the work this plane does with ease. reply | | Athena Sieben, e-mail, 28.11.2010 21:16 Hope someone can help me, looking for diecast models of the otter and twin otter for my nephew. Can anyone help me with where to look. Can not find them so far. Also looking for diecast of the Husky, Goose and Mallard.
Thanks Athena reply | | jim wittel, e-mail, 22.11.2010 23:01 Got a web site on the 63 Otters that came to the 18th and the unit history of the 18th Aviatiion Company. Check it out esp chapter 3 I need 27 more pictures by tail no to complete the entire 63 Otters that came through the doors of the 18th in Vietnam. Some of these Otters from the 18thare still flying today as DHC-3T reply |
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