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andymartin

Aerosoft Twin Otter Extended

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Hi Andy

 

I have it and is a while since I flew it as I have been away out of the country. What is it that you'd like help on?

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Thanks for the link to the aerosoft forum but ive posted questions on there and found them to be the most unhelpful users and therefore the most useless forum ever.  

 

I find the figures in the manual to be very inaccurate, especially the take off speeds/configuration, and landing speeds/configuration.     It is impossible to take off or land at the figures quoted, even though they have come, apparantly, from the real world manual.    I cant seem to get it to lift off at much below 80 kts, even at flaps 20, and they quote rotate at 65 with flaps 10!

 

The autopilot does a strange thing when i level out and engage it in altitude mode it noses down and dives.  The altitude select is higher than im actually at so it cant be that.   Maybe it needs to be very accurately trimmed manually before engaging autopilot?

 

Would appreciate any advice

Regards

Andy

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As to the autopilot, here is a helpful two part video:

 

 

I should add that you should be mindful of the CG with this aircraft. It does impact its performance.

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I have watched that video and i understand how the autopilot is supposed to work but it does do some strange things.  As well as diving when initiating alt hold, if when climbing after take off I initiate the ias , it doesnt even hold the speed .

 

I use the fuel and load planner so i presume it accurately takes care of the CG when adding/reducing payload as there doesnt seem to be a way of loading it manually.

 

Thanks

Andy

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Is the plane trimmed properly before you turn on the AP?


Don't touch the stick at all when AP is turned on as well, there's a lil knob I think in the back of the yoke I think (trying to remember) it's with the Anti Yaw button.. you use that to adjust pitch.. you only click Alt when you achieve the desired Alt..

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As to the autopilot, here is a helpful two part video:

 

Wow, nice cockpit. That guy must really love the Twin Otter. Good for him. 

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I use the fuel and load planner so i presume it accurately takes care of the CG when adding/reducing payload as there doesnt seem to be a way of loading it manually.

 

I've found that the Twin Otter Extended get severely tail-heavy with less than full fuel, especially with a heavy payload.  Checking CG in the FSX/P3D fuel and payload dialog showed CG well aft.  What I've done since then is to load it in the Aerosoft planner, then work back and forth between the planner and the in-game dialog box to get the balance right.  The less authentic but effective solution is to load full fuel and no payload - it seems to trim out best in that situation with no other adjustments needed.  Would be interested to know if others have had this experience or if it's just something peculiar to my system (or my lack of skill...)

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Just doing test flight from Prestwick to Liverpool. had no problems lifting at around 80kts.Steady climb-out to selected ALT of 10000.IAS is steady at above 100kts while climbing but as soon as I reached 10k and selected ALT, plane levelled off, and the IAS increased to settle steady at 165kts. Will report on descent phases and landing at Liverpool later. But so far, no issues.

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There seems to be some "ground friction" problem with the Twotter, specifically the power needed to taxi is ridiculously high for me.

The first releases of the plane didn't show this, but the final product release that included the -100, and amphib models seems to have it.

There has been speculation that it some how has something to do with the plane's interaction with ORBX scenery, but I can't say for sure any more, since my entire 

FSX world is either covered by FTX Global or Full Fat regions.

 

It has been a bit frustrating, as the Aerosoft answer to this is that FSX has problems with ground friction (which is true), but since the plane behaved better before the final release in any scenery situation, this explanation falls a bit flat. Still, the Twotter is one of my favorite planes, and my go to weapon for almost all back-country and bush flying.

 

As always, this is my personal experience with the aircraft and YMMV.

 

Chris B.

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Using UK2000 Scenery airports. That FSX friction issue could well be the cause of the 'sticking'.

 

Agree, the previous Twotter before the Extended was a better model.

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Agree, the previous Twotter before the Extended was a better model.

 

I actually quite like the current X model vs the original - what I was referring to is that Twotter X  came out in stages, and I bought in from the beginning, when only the "wheeled" and "tundra" tired versions were initially provided, and these releases were just fine (if a bit twitchy with the usual FSX Turboprop issues) - it was only the latter releases of the Twotter X that had these ground friction problems for me - and none of my other favorites like RealAir, PMDG, A2A, Majestic, and even some Carenado's (like the 337),  have ever shown this "stuck to the ground" business... :wacko:

 

You can even tell that this "stickiness" varies between runway/taxiway material types as you proceed...

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After just landing at EGGP, with no issues, I now realise why I parked/shelved this in the Hangar----it requires so much throttle just to 'unstick' it. Not found this to be an issue with other Aerosoft aircraft.

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There seems to be some "ground friction" problem with the Twotter, specifically the power needed to taxi is ridiculously high for me.

 

Other than there is a ground friction problem built in to both FSX and P3d, the Twotter is still a hair different. Because there is a lag caused by turbine spin-up, it can be very challenging to taxi the Twotter. Keep giving it more throttle until it begins to roll, then back down using the torque gauge as your guide.

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Other than there is a ground friction problem built in to both FSX and P3d, the Twotter is still a hair different.

 

I did not really see much if any difference with the TwotterX's taxi behavior in its initial release compared to any other FSX turboprop, they all have a general tendancy to over-surge after a throttle application, and most have so much "get up and go" that you had to look to your brakes first and then perhaps reverse thrust to manage the speed - unlike say the RealAir DukeV2, which is incredibly manageable by just manipulating the low/high idle power settings.

 

Once in the air, the TwotterX did (and still does), represent a much better than "FSX default" operating behavior experience, that is close to, but not quite in RealAir territory. However, the amount of power required regardless of gross-weight to unstick it in later releases is pretty absurd. Again, this may be some anomoly related strictly to a change in my installation...

 

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Im using orbx airports and  dont have any ground sticking issues.   There is a long lag, true to the real aircraft, between applying power and the engines responding, so you can end up giving it too much welly to get it moving.  Small adjustments i think is the way to go.

My 2 issues are the data charts, which seem wildly inaccurate.   And the autopilot.

The charts state rotate at 65 kts average weight aircraft, flaps 20.  I find this impossible,  Even with maximum up trim it wont rotate much under 75.   It then rapidly increases speed even though the charts state climb at 85.  I can eventually achieve 85 after flaps up and throttling back, still seems a very nose high attitude.

Landing at anything under 80 flaps 2 without getting a seriously nose high touchdown seems impossible too.   Im landing at 80, 11-15 hg, flaps 20 or 30 and can get a decent shallow flare at touchdown.

The worst thing for me is the autopilot.  When climbing out, after trimming, i set the ias on the autopilot and instead of climbing at a steady rate it bucks the nose up and down.    After leveling out and trimming i set the altitude hold and the aircraft immediately dives.   When i take control and level out and select altitude select again, the autopilot is fine, but it always takes 2 attempts.    It seems that the trim is critical in the twin otter before engaging autopilot?   

 

Having said all that, i love this aircraft,  perfect for short flights and a challenge to manage the engines and props.  

 

Thanks for the helpful advice

Andy

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i set the IAS on the autopilot and instead of climbing at a steady rate it bucks the nose up and down. After levelling out and trimming i set the altitude hold and the aircraft immediately dives.

I had the same in my short flight to Liverpool yesterday, so I switched it off and controlled the speed from, my joystick throttle.

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 Small adjustments i think is the way to go.

 

Wish that were the case for what I have been seeing, but for me it is not - I am actually starting to look into whether or not I have some kind of brake pedal sensitivity or null zone issue when I load the plane, as I can run up the engines quickly or gradually and it makes no difference at all, the Twotter will just sit there like its tied to ground (regardless of gross weight)  - eventually at high enough power settings it will break away and then start to accelerate like a scalded dog - Interestingly, when the A2A 172 first came out, many people were having the same sort of brake/stuck issues, and eventually A2A was able to deliver a fix - that won't happen here as Aerosoft has moved on in regards to this plane quite a while a ago, so I will just have to keep tweaking I guess...

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Im using orbx airports and  dont have any ground sticking issues.   There is a long lag, true to the real aircraft, between applying power and the engines responding, so you can end up giving it too much welly to get it moving.  Small adjustments i think is the way to go.

My 2 issues are the data charts, which seem wildly inaccurate.   And the autopilot.

The charts state rotate at 65 kts average weight aircraft, flaps 20.  I find this impossible,  Even with maximum up trim it wont rotate much under 75.   It then rapidly increases speed even though the charts state climb at 85.  I can eventually achieve 85 after flaps up and throttling back, still seems a very nose high attitude.

Landing at anything under 80 flaps 2 without getting a seriously nose high touchdown seems impossible too.   Im landing at 80, 11-15 hg, flaps 20 or 30 and can get a decent shallow flare at touchdown.

The worst thing for me is the autopilot.  When climbing out, after trimming, i set the ias on the autopilot and instead of climbing at a steady rate it bucks the nose up and down.    After leveling out and trimming i set the altitude hold and the aircraft immediately dives.   When i take control and level out and select altitude select again, the autopilot is fine, but it always takes 2 attempts.    It seems that the trim is critical in the twin otter before engaging autopilot?   

 

Having said all that, i love this aircraft,  perfect for short flights and a challenge to manage the engines and props.  

 

Thanks for the helpful advice

Andy

Hey Andy,

 

You are very much correct. As a Twotter pilot, I find this bird flies very wrong, especially in takeoff and landing configurations. In the real bird, I'm flying a visual approach at flaps 20 and 76 knots and I'm flying with a serious nose down attitude. The original Twotter flies exactly like this. The Extended flies at that speed in a nose level attitude or a nose up one depending on landing weight. Flaps 10 on takeoff in the real bird if I'm lightly or moderately loaded, sees me off the ground at 60 knots. Flaps 20 and I basically "helicopter" off the ground (no rotation and the thing flies itself off the ground in a nose level attitude). Full flap landings and I can fly at 50 knots and below STILL WITH A SERIOUS NOSE DOWN ATTITUDE! To get her on the ground, pull the power off, wait for her to start sinking then flare her out. Drop on the numbers and stop 100 ft after that(with a nice headwind). Do not try that with the Extended. Thing wants to land like a 747. The original Twotter replicates that perfectly. My opinion, take the FDE of the original Twotter, adapt it to work with the Extended. I still fly the original Twotter. Have the extended but don't touch it. Going into St Barths with that...? Doable....but takes the whole runway.... Riiiiiight.... Ama stick with the original.

 

Cheers.

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Hi Aeromaestro,   many thanks, that is really interesting to hear from a real pilot.    Ive never been in a real twotter(maybe one day)  but the extended just didnt seem accurate, especially when i compared the data charts and also videos on you tube of take off and landings. 

Maybe i will go back to the original aircraft and stick with that !

 

Thanks again

Andy

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Hey guys,

 

For what it's worth, the Extended is a masterpiece of flightsim engineering. It's just really lacking in flight characteristics. If Bernt Stolle or someone of his calibre had a go at an alternative FDE for it, it probably would be a marriage made in FSX heaven. I personally wish someone could take FDE and .air files from the Twotter X and merge it with the Extended. Awesomeness it would be...

 

 

Cheers

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Having seen this thread yesterday, I had to take the Twotter Extended for a ride last night to see what all the fuss was about.

 

As far getting it to start rolling goes, maybe I'm just used to it, but I have no big issue with applying power, waiting for the engine to supply it and once rolling reducing the power to taxi.  Just how much power should be needed and how quickly it appears after moving the throttles.....I have no idea.

 

Similarly, the take-off and landing speeds 'seem' fine to me but I probably need to be a little more precise in terms of looking at weights and speeds..........on the other hand, is that how this kind of aircraft is really flown?

 

The autopilot did everything I expected it to including holding altitude.  In fact I found it enjoyable using IAS mode to hold speed together with the required climb or descent for any given power setting.  I can't help wondering if others are using the AP as it was designed to be used.  If anyone has an issue with say alt hold and would post their fuel/weights etc here, I'd love to try and recreate the problem.

 

That said, I certainly agree with you Aeromaestro about the speed/flap/pitch issue, it's almost like there's a lack of lift from the flap settings.  The fact that very little control input is needed to stay on a glideslope also points to this; I'd expect quite a bit of lift from each step of flap together with needing to push the nose down to avoid any ballooning effect.  That of course is not a big deal to fix on its own, however, the knock-on effects might come out elsewhere. 

 

That said, the aircraft was modelled on a specific aircraft the developers had access to, and the beta team included real world Twotter pilots, so maybe they don't all fly the same?

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