Aircraft add-on for Microsoft FSX

"I was slightly surprised to find that I had flown two particular turboprops a lot more than anything else and that the Aerosoft Twotter, which I have had for a considerably shorter time than the other one, was top of the list."

There can't be many FS aircraft that, when you look at the aircraft selection screen, list at least one livery from every continent on Earth. Yes, in this instance, that includes Antarctica.

It's not impossible that you could do it with the Lockheed C-130, that's a little ubiquitous too. Almost definitely the DHC-2 Beaver, although I can't think of an Asian livery for that offhand... Certainly, out of the box as a product, I can only think of one, and that's this one - the de Havilland Canada DHC-6 Twin Otter.

The "Twotter" is an interesting aircraft at the best of times. Its heritage is evident from the name, it was originally designed as a twin engined turboprop derivative/replacement for the company's own DHC-3 Otter / Turbo Otter, but not only did they build on what they already had, they created an aircraft that despite going out of production in 1988, still flies regularly, usually in commercial service. To top the lot off, the aircraft is still so popular that Bombardier Aircraft, who now own the DHC brand, have sold the DHC-6 type certificate to a company called Viking Air, who are restarting the line with a new -400 series aircraft due for first deliveries in 2009.

Not bad for an aircraft conceived in the early 1960s, is it?!

Being as popular as it is, there have been remarkably few Twin Otters developed for Microsoft Flight Simulator over the years and only two of these packages have ever been mainstream payware. The development of them has at least one man - probably a lot more - in common, but Aerosoft's latest aircraft release for FSX only has a lot to live up to compared to the real aircraft!

Video courtesy of Aerosoft/Jaggyroad Films


The Aerosoft DHC-6 pack weighs in at a fairly hefty 192Mb to download, but after doing so, you will be presented with Aerosoft's usual high quality, easy to work through installation executable.

There aren't really any options with this aircraft, being FSX only and relatively simple, so the only real interaction you'll have with the installation routine is to enter your security information to prove you bought it and to confirm the path to FSX. After that, it's a case of watching a blue bar for a short time and the usual bits at the very end.

One nice thing about the Aerosoft installation routine is that rather than giving you a large collection of individual Start menu entries for each program you have of theirs, it groups them together inside one "Aerosoft" header, with a Twin Otter X subfolder below it containing links to the uninstaller, load tool and manual.

"Un-installation, if required, can be carried out either from the Start menu or Control Panel / Add or Remove Programs and, after installing the Twin Otter, other Aerosoft uninstallers such as the Beaver pack and Budapest scenery continued to link to their own packages rather than trying to uninstall the Twotter.

The version used for this review was the original release, which has since been patched a few times, so whether the download includes these patches or not I cannot comment - they're available via the support pages if not but the version 1.11 version itself came out as a 125Mb file!


The manual in this one is not insignificant, either.

Aerosoft download product manuals have always been very well presented and put together, this one is no exception, a 115 page PDF file that combines the details of the aircraft provided, explains a couple of design decisions (albeit one I don't agree with, but I'll come to that shortly!) and provides operating instructions for the package.

In addition, this time, the developers of the package have included some bought-in FS9/X gauges to provide a degree of system depth to the aircraft and the manual is multiplied in size appropriately to explain the functions of these, particularly the KLN-90B GPS system, which takes up the vast majority (76 pages!) of the manual.

Because I'll discuss the GPS and radios under the 'interior' section below, I won't go into any more depth here - suffice it to say that the documentation is, as usual, very good and well worth the read. Of course, being a typical simmer, I didn't do that and just went looking for something to fly!!!

Before I move on to the next section, one thing I do have to mention is that if you look in your [FSX]/Aerosoft/TwinOtter directory, you will find a little application called "TwotterLoad.exe" - as the name implies, this is a load manager for the package, allowing you to select each model individually and alter the passenger, crew and cargo loads. Each click on a seat switches it between empty, male passenger, female passenger, child, then back to empty. Yes, you can have a child in the co-pilot's seat, but Hans Hartmann, who wrote the application, has programmed the pilot's seat to only accept a male or female selection. The load manager only changes the load-out, not the visual model, which I can now actually get to talk about.


Like Aerosoft's other de Havilland product package, the DHC-2 Beaver that I reviewed a while ago here, there are a number of variants included, covering two versions, the short nose original -100 series and the longer nosed, arguably more famous, -300 series. No -200s or the upcoming -400 series are included, nor are versions on tundra "bubble" tyres or amphibious floats. Although I agree that the bubble tyres would be a lot of work for no gain within the sim, the lack of an amphibious version is the design decision I disagree with, along apparently with many other people in the FS community who are still campaigning for one. The reasons given by Aerosoft for their lack of inclusion (cost and weight, therefore limited use in the real world) aren't factors for FS users and comparing these factors to the lack of detailed floatplane bases in FSX, meaning that water-to-water operations aren't massively realistic, the ability to fly from land-to-water or water-to-land in FS is far preferable for many "bush pilot" users.

Anyway, even without an amphib, there are more than enough versions here to keep you occupied and cover the planet:

The DHC-6-100 (short nose) is represented in fixed ski, float and wheeled configurations.

The DHC-6-300 (long nose) is represented in retractable ski and wheeled configurations only, but has two different cockpit variations selectable from the list, which again I'll cover in the 'interior' section of this review.

Although there are -100 long nose models, -300 short nose models and -300s on floats in the real world, the differences between them aren't really that dramatic and the range provided here is more than adequate, with a nice array of well presented liveries covering famous aircraft such as a "Yeti Airlines" aircraft that operates to Lukla for Everest expeditions and the Loganair/British Airways aircraft that operates the shortest scheduled air service in the world.

One thing of particular note, which Aerosoft have made a big deal about with good reason, is the detail they have put into the undercarriage of the ski models. Other than that, with only one interior (passenger) covering all but the specialist skydiving model and the basic shape remaining the same throughout the range, there isn't anything I can jump on to give as examples of how well these aircraft are presented. They are, though, very accurate to the original and are both modelled and textured well. Additionally, a paint kit has been released for them and a number of new liveries have become available as a result, covering most of the types and including some absolute gems.

The usual array of animated parts are provided, with the only real highlight being the skis I already mentioned. The only real issue with the package, from my perspective, is that only one "exit" command is animated, opening both the side passenger doors and the pilot's door at the same time. None of the other accesses can be used and no airstair option is provided.

In general, there is nothing big to really complain about in the external model as provided at all. It looks good, it's well textured and realistic.


As I said in the Exterior section above, only one cabin configuration is provided for the vast majority of this package, covering an 'airline' passenger configuration.

The interior of a model makes little difference to me and I'm quite happy flying a freight livery with seats visible through the windows personally, but I have read a couple of comments around the internet that perhaps Aerosoft should have modelled/included an empty and loaded cargo version. The answer, from replies to a variety of topics regarding the inclusion of additional models, by Aerosoft is that they consider the seven models already included to be enough for the pack. Considering the amount of work involved (effectively doubling this to 15 individual models, assuming the cargo would be "dynamically" loaded using a keystroke or similar to the empty model) I'm inclined to agree with that decision. Whether that's a deal breaker for the reader is a personal decision, but I'd counsel strongly against turning the aircraft down just because of this.

One of the reasons is that overall, the interior modelling of the Twin Otters is very good indeed. No 2d panel is included, although there are a few pop-ups and, from that, it's self evident that the aircraft is designed to be flown from the VC, which is definitely the "standard" for the current generation of MS Flightsim add-ons.

As I said earlier, there are two panel configurations provided for the overall very similar flight decks, one providing a 1960s/70s communications array of mechanical selection/display radios, the other a more modern set with LED/LCD displays and a GPS. Both panels include the default FSX autopilot gauge from the Maule, so FS bush pilots should be very familiar with the operation and quirks of that.

For this particular package, Aerosoft have bought in the communications and navigation radio gauges from Don Kuhn of FS2x, with the result that a considerable amount more functionality is included than would have been were the default Bendix-King radio stack elements used.

Because the "modern" radio stack is actually the same or a very similar series to that used by the default aircraft, there were a number of complaints when the aircraft was first released that things "didn't work". This wasn't true in the vast majority of cases, they actually worked a little more realistically than most sim pilots are used to and a quick scan of that nice thick manual was in order.

One of the C152s I used to fly was equipped with almost exactly this set of radios and, without having read a manual, I never had a clue that half the features available on them existed! Direct entry mode, frequency memories... I'm not sure how many of them I would have used in Lima Romeo, but they are all recreated here and accessible with a variety of button presses. However if you want to keep things simple, they can also be used exactly the way the default ones are too, setting the frequency on the standby side and then just pressing the transfer button to switch them to active. One bug I did find with the modern radios is that they work when "powered off" - a minor thing, really.

You get two GPS options on the modern panel as well. Actually, that's not true, as only the ageing KLN-90B unit is built into the panel, but the default hand held GPS is available as a pop-up should you need it. Unfortunately, I have needed it regularly, as the only way to point the add-on one to fly anywhere is via the FS flight planner, there is no direct entry mode here. What the KLN-90B does provide is the majority of the other navigation and information modes that the real unit provides, accessible via two dual-level knobs set either side of the central screen. Once you've learned that the left knobs control what is displayed on the left side of the screen and the right knobs control the right side of the screen, it's pretty easy to use - learning which pages display what and in what selection subset is another matter altogether. I'm still working on that and regularly call up the default GPS pop-up instead because it is easier! As I said earlier, the vast majority of the manual is devoted to the various pages and functions of this single gauge and it is worth the time to sit down and study these, if you want to use it.

Getting away from the radios at last, the rest of the gauges and switches in the cockpit are clear and easy to read, if rather basic in design - intentionally. This is not a complex aircraft.

That isn't, however, to say that it's a ctrl-e-and-fly aircraft, either. Not every switch on the overhead is functional and those that aren't functional aren't animated, but they are modelled. Those that are required are both functional and animated, allowing you to operate the aircraft in a realistic manner without having to refer to those 2d pop-ups I mentioned unless you are having problems reading a specific gauge.

I don't know whether this is the case on the real aircraft, but one good feature is that Aerosoft have not "spring loaded" the starter switch, which means that to start the aircraft you can put the starter switch in the left position with the fuel control at Isolate/Cutoff and then, when the turbine is spinning, pan to the fuel lever and move it to start the engine. After start, clicking the start switch again moves it to the middle position, then the right, then back to the middle. This is typical of how the Twotter has been designed - while it may not be 100% completely accurate, it is easy to use and logical. There were a few bugs and missing things when the aircraft was first released, but over the period of a couple of patches, we now have a glideslope, marker indicators and a DME, amongst other things and some flight dynamics patches (that's the next section!).

All round it is a well produced, easy to use package with enough depth for most people who would want to use it. The only thing I'd like to add to it, personally, is a GPS with direct input functionality but as I only know one of those for FSX and it is proprietary, tied to one specific add-on (also published by Aerosoft, but developed by a different team), they're forgiven for not including one.


The real world Twin Otter is best known for its ability to take off from, and land on, strips that would be impossible for almost any other commercial aircraft to operate using. In FS, the same applies. I don't have Aerosoft's Lukla package, so I didn't have the sloping runway and my approach was actually slightly easier, but the Himalayan airport is a typical example of the type of ridiculous place that real world Twin Otters operate around.

One thing that is worth noting is that while the vast majority of FS turboprops have a tendency to be limited by torque, the primary limiting factor I have found on the Aerosoft pack is actually the engine temperature. It doesn't take much throttle to move the needle into the yellow arc, especially on takeoff, and just putting on full power will still leave you well short of maximum torque, but will send the temperature gauge easily into the red. According to posts on both the Aerosoft forum and elsewhere, this is more accurate behaviour than the more conventional FS turboprops that the package was originally released with and has been refined over the patches.

Another interesting trait with this model is that because the engines and wings are mounted above the centre of gravity, the effects of power changes that most pilots would expect are reversed. This means that when applying power, rather than going up as it would conventionally, on the DHC-6 the nose will pitch downwards and vice versa - a decrease in power will actually pitch the nose up. This caused a number of problems with early versions of the add-on as the effect was rather pronounced and, especially at the aforementioned Lukla add-on, resulted in a large number of crashes. In the current version at the time of writing, this is far less the case, but is still present.

Regarding the flight envelope, putting the throttle in the position I would expect for "cruise thrust" gave me a torque reading of 35, engine rpm a little over 90% and about 140KIAS. At the other end of the scale, testing gave me the same straight and level clean stall speeds (throttles closed), regardless of which model I was flying, of 69KIAS. In approach configuration with full flaps, both wheeled versions stalled at 55KIAS, the float version slightly faster at 60KIAS. The float version also dropped faster when the stall developed, reaching 1500fpm down very quickly indeed.

In either configuration, actually maintaining straight and level right at the bottom end of the flight envelope was not that easy. The autopilot couldn't manage it and I had to work hard to do so manually. The nose really is very high, so you get a lot of warning that you are entering the danger zone before the stall warner sounds. I've experienced wing drops to both sides during stall testing, but it seems to prefer dropping right, after a brief wings level descent, so you also get a few seconds to react and recover by applying power and lowering the nose before it tries to kill you. Indeed, on a few occasions, I have actually applied power and kept the nose up, which has allowed me to get out of some very tight spots without running into cliffs or hills.

The big placard on the panel says "Aerobatic Manoeuvres And Intentional Spins Are Strictly Prohibited" so I decided to obey that and not try and spin it, but on several occasions, I have had cause to sideslip the aircraft and that works exactly as I would expect it to. I have also spent a significant amount of time flying the aircraft in a "low and slow" configuration and it maintains controllability right up to the stall, whether flaps are retracted or extended.

Regarding takeoff and landing runs, I have no yet found a runway that the Twotter can't cope with other than microlight only fields, where you really shouldn't be trying to take a twin turboprop anyway! It has easily got into the place where I take new floatplanes to test their STOL capabilities and it did land within and get out from a European football pitch texture (well, you have to, don't you...) - I didn't try it in any of the stadiums, though, sorry.

Ground handling is simplified in this model, in that the developers have linked it to the rudder pedals rather than, to quote the manual, "a half hidden stick in an awkward place" which you would have to have controlled using the mouse. This means that there really are no surprises here. The floatplane is slightly different in that a "hidden water rudder" previously discussed on the Aerosoft forum has not been included so the only way of turning the floater is, as per the real aircraft, differential thrust and full deflection rudder. Unfortunately this is a bit of a problem for joystick fliers who don't have two differential throttles. It can be resolved more easily in FSX, where at least the e-1, e-2 and e-1-2 controls actually seem to work properly, than it could in FS2004, fortunately.

To sum all that up, this Twin Otter in all guises is a very nice aircraft to fly. The STOL capabilities that are critical to recreate in an aircraft such as this are here and great fun to test. There are a couple of quirks to learn, such as the reversed pitch change, but nothing too over dramatic.


The night before I wrote this conclusion, I downloaded and installed a little tool which extracts and breaks down a lot of information from the FSX flight log, giving you, amongst other things, a total time per model breakdown of your hours. I was slightly surprised to find that I had flown two particular turboprops a lot more than anything else and that the Aerosoft Twotter, which I have had for a considerably shorter time than the other one, was top of the list.

Despite my issues with the choice of models and the resulting fact that I have used the wheeled versions far more than anything else for non-test flying, it's a very well presented and extremely versatile package. It'll suit bush pilots, airline pilots, military pilots... OK, so it won't do Transatlantic or Transpacific in one hop, so if that's all you ever fly, this one isn't for you. Other than that, the links below take you to the purchase pages! ;)

Find out more about the Twin Otter at the Aerosoft web site or simMarket.   

If you'd like to comment on this review, please use our forum to do so.   

Ian Pearson is a real world CAA PPL-IMC qualified pilot (unfortunately now lapsed) who has been hooked on civilian flight simming since Mail Pilot on the Commodore 64 and Thalion Airbus on the Amiga. He joined the MS Flightsim world with FS4 and almost immediately FS5.1CD, which was when his first attempt at designing aircraft went seriously pear shaped and he gave up. He has Beta tested for a number of well-known organisations and teams from FS98 through to the present day, but still hasn't found a way of making his addiction to Flight Simulation pay for itself, so officially works in the railway industry in the real world.

Nick Churchill has been providing images for marketing purposes of Flight Simulator products for several years and claims that staring at a virtual cockpit for too long can make you go blind.

Cody Bergland created Jaggyroad Films and has been a leading force in marketing in the flight simulation community. His works spans across many companies and stand alone products. Cody served 5 years active duty in the USAF as an electronic warfare technician but now dedicates his free time to his hobby of flight simulation and video production.


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