Aerosoft DH-6 Twin Otter

There has been a lot of criticism in the Microsoft Flight Simulator forums about this aircraft, with the loudest opponents stating that it was released too early. I won’t broach that subject here, but rather have a pragmatic discussion of what seems to be correct about the aircraft and what needs fixing. All opinions welcome.

Sounds
I hear a lot of sounds that do match what I remember about flying in this aircraft, especially the takeoff, climb, and cruise power settings. But there are a lot of weird sounds as well. Things like flaps moving without moving the lever, transitions between various RPM levels (seems either on or off), what sounds like banging against the fuselage, wind and tires on tarmac when the plan is stopped. To my uneducated ears, it sounds more like the programming to get the proper sound at the right time or trigger needs work. Also, the bank angle and descent warnings sound early IMO, like any time over a 15 degree bank. There is rumored to be a patch to fix some of the issues this weekend. Edit: More info. I’m running the alias mod from flightsim.to which I believe is using the King Air 350, until a suitable patch is out. Not perfect, but better than default IMHO.

Sound volume
This topic is very subjective and staggers under the weight of what sim pilots think it should be, even if they’ve never ridden in a Twin Otter, much less piloted one. My memory is that Twin Otters are loud as ■■■■ inside. They are square aluminum boxes with twin turboprops mounted on high wings. From what I’ve seen, pilots universally wore headsets when operating them. And from experience, if climb power is set, you more or less have to scream at your neighbor to be heard. In that regard, I feel that the default volume in the cockpit should be about where it would be with David Clarks on, but louder everywhere else. Needs improvement, but not deal breaker.

Flight model
This is receiving a lot of criticism, especially those who think that it leaps off of the ground at unbelievable speeds and that it won’t stall. I wanted to put this to a test, but finding a free Twin Otter POH in PDF format is hard. If someone finds one, respond here with a link. What I ended up doing is do a pseudo install of of FSX, so that I could run the install routine of Aerosoft’s Twin Otter Extended, which I remember had a pretty good set of manuals. In the data PDF I found the following, which I will assume are based on the real aircraft.

Edit: I found the airspeed limitations on page 86 of the MSFS version manual. They give similar numbers, but there is less data, like Vr speed.

DH-6-300
(wheels, CAS, sea level)
Vmc 66 (64 in the current manual)

Vr (12,500) 69
Vr (9,500) 64

Vfe (0-20) 102
Vfe (10-37.5) 95 (93 in the current manual)

Va 136 (132 in the current manual)

Vs is not given and you can make arguments for or against it being equal to Vmc, because both numbers move, but for this discussion, we’ll assume that it is equal.

I tested the stalls at MTOW at 2000 MSL. If cut power (approach to landing) and apply max aft elevator deflection, it’s hard to get a break. It feels similar to having a front canard in that you don’t get a break, but the aircraft is descending and the VSI shows vertical negative acceleration. I’m not sure if this is a limitation of the sim, or needs work. If you add a bit of power (accelerated) and hold neutral aileron and rudder, you will get a break to a gentle rotation left which will continue until you apply appropriate recovery input (relax back pressure, neutral aileron, and rudder opposite the direction of spin). This feels completely normal to me.

If I am at MTOW, set elevator trim to neutral, apply full power, at rotate at VR (69), the aircraft has a normal takeoff. If I rotate at 55 kts smoothly, the aircraft won’t start flying until ~65. If I pull back aggressively, it will leave the runway, but the stall horn sounds, and the plane begins to roll right or left to stall, as it should. I’m really not seeing any bad behavior here.

I haven’t done further testing, like exceeding Vne. But so far the Twin Otter seems to be flying at least near the numbers.

I need to take a break, but more to follow. What have you found?

4 Likes

Your memory is correct!

2 Likes

I don’t have the virtual one, nor have I ever flown the real one.
I do, however, have several colleagues that used to fly the real deal.
They all say you could do anything in the Twotter, but go fast.
One even got thrown belly up by a rotor wind. «I just rolled her right again».
So a forgiving nature sounds about right to me…

3 Likes

image

2 Likes

Does it descend pretty rapidly will the throttles at idle? Most aircraft with the PT-6 have the ability to point downhill pretty steeply and at idle power the drag on the props is enormous…so I would think it should be able to come down and stay on speed with a pretty good negative pitch angle.

3 Likes

The RAF sometimes displays a B200. It always has included a very steep approach. My boss reckoned they had placed the props in ground idle briefely as he routinely did steep approaches when we had no patients on board.

2 Likes

It should, but I think that is universally not modeled in MSFS. At least I hear others complaining that the props in (fill in the blank) third party aircraft have no drag at idle with the prop levers fully forward.

I remember taking an Eastern Metro Jetstream 31 from KMYR to KATL, sitting in a front row isle seat so that I could observe the flight crew (before sterile cockpits) and watching the PF pitch over from cruise alt and point at the runway threshold at Hartsfield. It felt like one minute we were at cruise, like 12k and the pilot just pointed the nose at the runway in the distance. This would have been in the late 80’s. That was when I remember contemplating that reciprocals and turboprops must be a completely different animal. :neutral_face:

1 Like

I’ve heard that @BeachAV8R puts his in beta if Marisa has tacos and tequila waiting.

4 Likes

Well, I concede that the Kingair is as close to this aircraft as I’ve ever gotten.

But, I’m generally grouchy AF, and I really don’t have any especially vitriolic gripes about it. Not that it’s perfect. But it feels and sounds to me like a turboprop of this class should.

I honestly don’t understand hate.

2 Likes

Change log for tomorrow’s patch…

We just lost the deadline for an update today (17:00 normally), so we have moved this to tomorrow. The main reason we needed more time was that the modelers asked me to allow them to work out some issues.

Aerosoft Twin Otter Update 1 Changelog

  • Added: GPWS Inhibit switch

  • Added: Wing lights

  • Added: Elevator and rudder trim knob animations now react to control input. Sounds added

  • Fixed: Torque link on -300 Cargo 4-Blade nose gear

  • Fixed: Changed Elevator and aileron simvars to those that work in multiplayer

  • Fixed: Control lock variable reversed for multiplayer compatibility

  • Fixed: Rework and volume balancing of external sounds

  • Fixed: Rework and volume balancing of internal sounds

  • Fixed: Autopilot losing altitude in ALT HOLD mode

  • Fixed: Autopilot losing altitude in GS HOLD mode

  • Fixed: Exterior view engine instruments

  • Fixed: Missing performance data in aircraft selection window

  • Fixed: Toned down wind sound at rear door when aircraft is not moving and wind is not storm strength

  • Fixed: Boost pump annunciator condition

  • Fixed: Volts indicator now shows 0V when generators are off

  • Fixed: CDI Needles jumping from side to side while flying a FROM radial

  • Fixed: Missing needle arrow in copilot HSI

  • Fixed: NAV/HDG flags over heading bug and needle in both HSIs

  • Fixed: Separated GNS530/430, Autopilot, Transponder and ADF from Copilot dimmer

  • Fixed: Propeller De-Ice now works for both propellers

  • Fixed: Intake Anti-Ice now works for both engines

  • Fixed: Increased volume of GPWS glide slope callouts

  • Fixed: HSI knob not turning

  • Fixed: Gaps in the ceiling near front cabin wall

3 Likes

2 Likes