De Havilland Canada DHC-6 Twin Otter
|Author(s)||Syd Adams, lanbo64, Patten, f-jjth, PAF team, Zdenal, Erik, primtala2, abassign, dg-505, others|
dhc6, dhc6F, dhc6S
The de Havilland Canada DHC-6 Twin Otter, sometimes affectionately called the Twotter, is a 20-passenger STOL (Short Takeoff and Landing) utility aircraft. It has often been called the most successful aircraft program in Canada's history. The Twin Otter is a high-wing twin-engine turboprop aircraft with a not-retractable tricycle gear, a non-pressurised cabin and two constant-speed props. In FlightGear, there are three versions available: Wheels, Floats (amphibious) and skis.
About the original
The DHC-6 Twin Otter is the further development version of the DHC-3 Otter of the same manufacturer. The development of the Twin Otter began in 1964, it's first flight was on May 20, 1965 . To keep the STOL abilities of the Otter, the DHC-6 got two powerful turboprop engines Pratt and Whitney Canada PT6A-20 with 410 kW at each turbine in the first version, the DHC-6-100.
In 1968, the Twin Otter was developed to a new version, the -200 series, which had improved STOL performance.
One year later, in 1969, the DHC-6-300 series was introduced, with more powerful engines, the PT6A-27 with 460 kW. Until today, the -300 Series is with 614 built aircraft the most successful variant of the Twin Otter. 1988 the production of the DHC-6-300 ended.
After 18 years of not-producing the Twin Otter Viking Air acquired the production rights from Bombadier Aerospace, and started producing a new series, the DHC-6-400, whose first flight was on October 01, 2008. The DHC-6-400 is equipped with modern state-of-the-art avionics and even more powerful PTA6-34 engines also from Pratt and Whitney. Until summer 2014, there were built 55 aircraft of the -400 series.
The aircraft's powerful engines, it's STOL abilities, and it's spacious cabin make the DHC-6 a popular aircraft for skydiving and well-suited as a bush plane for inacessible and remote terrain in many developing countries.
The FlightGear version is the DHC-6-300 Series.
After some time of silence, in early 2014 the Twin Otter got under active development again. Until today (Jan. 2015), the visuals (mainly the interior, thanks to Patten and the FlightGear PAF team) and the electrical systems reached many improvements. For example, lanbo64 implemented a startup procedure which comes quite close to the reality.
In addition, dg-505 created an extensive tutorial system, which makes it easy to learn the standard operating procedures, and a number of checklists, which are taken from real Twin Otter Checklists. Richard Harrison is currently working on an interior shadow cubemap.
Currently, the twin Otter is still under active development. If You are interested in helping to make the Twin Otter even better, You are welcome to join!
|This section contains a review. Please note that statements made here are (mostly based on) a single person's opinion.|
Note that this review is about the actual version (January 2015), so some things may change in the future.
The Twin Otter has a accurately modelled 3D model. It has some details like the nose gear, the hinges for the ailerons/flaps, or the pitot tubes. All control surfaces are animated (ailerons, flaps, elevator, rudder) and the amphibious version has a retractable gear with two nicely modelled floats. The doors are animated and open/close by clicking on it. In the basic version there are some liveries included, which look partly really good. Many more liveries are available in the FlightGear Livery Database.
About the interior I have to say that both the cockpit and the cabin are quite accurate. Both have photo-realistic texturing, which is, at least from my point of view, very important for good optics. The interior gives some attention to detail: For example, the cabin has a extinguisher and a seatbelt/no smoking sign. Same thing in the cockpit: The Twin Otter has a very detailed cockpit with almost every instrument working and most switches animated and functional. In my view, the cockpit textures deserve a special mention. As said, it is photo-realistic textured and some of these textures look slightly worn, which gives the appearance of a pretty old, frequently used aircraft. Hats off to the designer(s), this looks really good and realistic.
Another nice function: If you want to know which instrument is which, you can press Ctrl+C to find out. Then you see also the clickable hotspots in the cockpit.
My personal wishlist concerning the appearance:
- A bit more detail of the skis
- A bit more detail of the props
- Some additional details like antennas, etc.
- Animation and implementation of the missing switches
Flying the Twin Otter
Starting the engines of the Twin Otter can be done in two different ways: First, using the Autostart button, which is absolutely NOT recommended because it's extremely unrealistic!. The second way is by using the checklists/tutorials, which guide you step by step through the procedures. If you aren't familiar with this aircraft and want it realistic, it could take some time to get the engines running.
Due to the powerful engines and the STOL skills, the twin otter flies after only a short time of accelerating on the runway. During the climb, the Twin Otter can prove her excellent climb rate: Near sea level a climb rate more than 1500 fpm is also with full fuel tanks and pax absolutely no problem.
In the air the Twin Otter is quite easy to handle. The reactions to the joystick inputs are direct but not too sensitive. As I haven't flown the Twin Otter in reality, so I can't say precisely how realistic the FDM is. But taking the size, the powerful engines, and the relatively small control surfaces into account, it seems to me, that the creator of the FDM has done a good job, and it comes fairly close to the reality.
The FlightGear Twin Otter is also equipped with an autopilot, which is self-explaining and easy to use, but in general I fly manually, because the aircraft is easy to handle.
Landing the Twin Otter is as easy as the rest of the flight. Just pull the throttles back, slow down, line up in front of the runway, and descent. It's worth mentioning that the flaps work very good, so if you need to descent fast for any reason, you can put full flaps, and descent at -2000 fpm without gaining too much speed.
If you only have a very short runway for landing, thrust reverse might be a useful tool. Right after touch down press the Del key and apply full throttle. Your Twin Otter will quickly slow down, and is healthier for the brakes if you use reverse thrust.
If you want have a challenge, try to fly a long-range IFR route in bad weather without using the autopilot. Because all navigation instruments are operated from the cockpit, radio navigation is simulated realistically. Before the flight you can search for the VOR frequencies, and simply navigate from VOR to VOR using the NAV-Display and the DME.
Or try try flying in the mountains, where the high climb rate and the maneuverability is essential, especially if the weather is bad.
- Never exceed speed: 170 knots (195 mph , 314 km/h)
- Maximum speed: 170 knots (195 mph, 314 km/h)
- Cruise speed: 150-160 knots (173-184 mph, 278-296 km/h)
- Stall speed: 58 knots (VSO, gross weight, landing configuration)
- Stall speed: 80 knots (VS1, cruise configuration)
- Range: 920 nautical miles (1,050 mi, 1,690 km)
- Service ceiling: 25,000 ft (7,620 m)
- MTOW: 12,500 lbs (5,670 kg)
- Rate of climb: 1,600 ft/min (8.1 m/s)