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Manta

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Hi there!

I'm a long time FSX user and, though I scarcely write to forums, I read them a lot. These days I'm enjoying a lot flying with your Twin Otter, which I find as an awesome plane both in terms of Flight Model, FPS friendly and 3D graphic/textures. I have been a lucky guy on this Autumn, 'cause I have flown in a Winair Twin Otter from Princess Juliana airport to St. Barth's and back with my wife, beeing the only two passangers aboard. We had a sit forward very close to the cabin which, having an open cockpit, let me see how the pilot and copilot managed to fly this incredible horse. If I remember correctly, taxiing was made with fuel levers and prop pitch at minimum. The route from the two islands was flown at FL15 (1500 ft). Along the route, copilot managed most the prop pitch not at his fullest while, before beginning to descend, the two levers were pushed to their fullest causing a lowering in pitch and a hard breaking. About this, I don't remember seeeing any caution light advising prop pitch not at his best when not at his fullest.

In youtube I posted something about this incredible though brief journey:

Thanks for what you created

Cheers

Fabio

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Great video - it´s always scary to watch a landing into St. Barth.

The Fuel levers are ON/OFF only, so it makes good sense that they where set to ON during the entire flight.

The Prop levers are to be set to full forward during taxi, take off and landing (to ensure full power in case of a go around)

The "RESET PROPS" will lit when the prop levers aren´t full landing and the throttle levers are retarded beyond flight idle.

So if You did not see it being lit, then the throttles has not ben reatrded that far aft.

Moving the proplevers from course towards full forward (fine pitch) will help decellerate, since the propeller blades will be more flat into the airflow, thus also increasing prop rpm.

Finn

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Hi Finn thanks for your reply.

It was very windy that day, as you can plainly see at the way my iphone moves around during landing. It was so windy that after our landing, planes inverted their approach all day. I can tell it since we were staying at Eden Rock's, very close to the airport.

As per the fuel levers, in FSX I use FSUIPC and it allows to have a three steps lever: Cut, Min and Open (Max). Most likely I just imagined that the fuel lever was used just like a mixture propeller lever.

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Regardless how You set them via FSUIPC, they will always be forced into what´s known as Low idle position (min).

And No - as Mathijs says, they are On/Off only.

On some Pratt and Whitney PT6 turboprops You have Cutoff - Low Idle - High idle, but not so on the Twin Otter

Finn

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Great video Eric.

Winair's engines must be a little thirstier than ours. I tried to read their gauges with a freezeframe. It looked like at 1500' cruise altitude they were running 75%np @ 35# torque and about 310# per engine fuel flow giving them about 120 +- KIAS. No way to know the ambient temperature on that day but the T5's were cool, running about 3.5.

For comparison I flew the same route at the same altitude with today's real wx. Surface temp was 24 Celsius. 1987# fuel, 3420# payload and at 35# torque and 75%np I was flowing about 220# per engine at about 130KIAS and a T5 of 6.5.

Wonder if the engines were "goosed" to flow a little more fuel than standard to keep the expensive hot sections cooler in the balmy Caribbean temperatures? Kind of like leaning to the rich side of peak EGT. A little more fuel flow may be cheaper in the long run than premature hot section replacement or shorter TBO's. I'm not very familiar with turboprop mechanics but maybe someone with more knowledge than me can advise if this is possible?

Obie

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  • 2 weeks later...

Regardless how You set them via FSUIPC, they will always be forced into what´s known as Low idle position (min).

And No - as Mathijs says, they are On/Off only.

On some Pratt and Whitney PT6 turboprops You have Cutoff - Low Idle - High idle, but not so on the Twin Otter

Finn

Right, Finn. As for the last comment, the earlier C90 King Airs (I flew s/n LJ680 a lot) had stop/low/high idle. You'd use the high idle for a cross generator start and then bring it right back to low for taxi, or if you were on the ground with one engine running and the electric heater on. The minus was you'll always have to make sure the condition levers were in low idle when landing, especially when landing at a high altitude airport (South Lake Tahoe in California/Nevada) or you'd never slow down in the flare and rollout. There was a little hook shaped cutout at low idle where you'd have to move the lever slightly back and inward to get to high idle, but it was still possible to get it there accidently. Or, worse yet, one there.. Just one more trap for the unwary.

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