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DHC-6 Twin Otter development

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Re: DHC-6 Twin Otter development

Postby erik » Mon May 29, 2017 9:51 am

By the way, here is some info for the DHC-6 that I dug up when developing the JSBSim FDM for the Twin otter:

http://www.pprune.org/archive/index.php/t-372165.html
The Twin Otter has been certified to many different standards - first to CAR 3,
then later to SFAR 23, then to the BCARs (British standards in the 1970s, prior
to JAR OPS-1), then to Australian DCA regulations (prior to publication of AFM
amendment 19 in 2002). Exaviator indicated that he flew in PNG in the distant
past, it is possible that he has quoted speeds, configurations, and power
settings that were applicable to the Series 320 (Australian) variant aircraft
prior to the publication of AFM amendment 19 in 2002.

FWIW, I've just finished writing an AFM supplement entitled "Performance to FAR
25 Standards" that will be published later this summer for operators who wish
to conform to JAA 'Performance A' standards, and for Canadian and American
operators who will be obliged to comply with the '2010 Rule' when it comes into
effect next year. That will add yet another variable to what is out there...

Here are the current numbers for SFAR 23 certification standards. These are
applicable to the Series 300 and variant standard landplane aircraft at the
maximum weights permitted (12,500 lbs MTOW, 12,300 lbs MLW).

Takeoff
- Flaps 10°, V1 73 KIAS, V2 80 KIAS, maintain V2 to 400 feet AGL minimum.

Initial Climb
- following flap retraction, Vy is 100 KIAS, a higher speed may be used at
the discretion of the pilot.

Initial Approach
- no less than 94 KIAS if flaps are up, or no less than 85 KIAS with flaps
extended to 10°.

Landing
- Flaps 20°, Vref 80 KIAS or
Flaps 37.5° Vref 74 KIAS

Cruise power is at the discretion of the pilot. At temperatures up to ISA +6°
at sea level, 50 PSI torque can be used for cruise. This is not a common
practice, because setting maximum cruise power results in a significant
increase in fuel burn but an insignificant increase in speed. Many operators
use about 480 SHP per engine for cruise, this can be achieved with a torque
setting of 45 PSI and a propeller speed of 75% Np. At this power setting, fuel
burn is approximately 300 pounds per hour (per engine), and a reasonable
compromise between fuel burn and cruise speed is achieved.

Some other useful speeds, again, at maximum weight for the phase of flight,
all in KIAS:
- Best Rate of Climb 100 KIAS with flaps up
- Best Angle of Climb 87 KIAS with flaps up
- Best Single Engine Rate of Climb 80 KIAS with flaps 10°
- Engine Failure after Take-off 80 KIAS, Flaps 10°
- Enroute Descent Flaps up, speed limited by Vmo
- Minimum Control Speed, One Engine Inoperative 64 KIAS.
Vmc is always given in the take-off configuration, thus,
flaps 10° is assumed.
- Stall speed, landing configuration (Flaps 37.5°) - 56 KIAS
- Stall speed, take-off configuration (Flaps 10°) - 66 KIAS
- Stall speed, flaps up 73 KIAS
- Manoeuvring Speed 132 KIAS from sea level to 18,000 feet.
Limited by Maximum Operating Speed above 18,000 feet.
- Glide Speed (both propellers feathered) for best range - 100 KIAS
- Glide Speed (both propellers feathered) for best endurance - 77 KIAS

Maximum Operating Speed 166 KIAS for aircraft SN 271 and higher in landplane
configuration, or earlier aircraft that are post Mod 6/1291 in landplane
configuration. 156 KIAS for all other aircraft. Vmo begins to decrement above
6,700 feet pressure altitude, but this normally does not present an operational
restriction.

Flaps Extended Speed Maximum 103 KIAS for flap extension up to and including
10°, maximum 93 KIAS for flap extension beyond 10°, both speeds quoted are for
post Mod 6/1395 aircraft. Mod 6/1395 cut in at SN 290 and can be retrofitted
to earlier production aircraft.


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Re: DHC-6 Twin Otter development

Postby jam007 » Mon May 29, 2017 10:48 am

Video of a DHC-6 take-off
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Re: DHC-6 Twin Otter development

Postby erik » Mon May 29, 2017 11:03 am

Hard to tell, it does rotate but I don't have the feeling it was explicitly necessary at that moment.

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Re: DHC-6 Twin Otter development

Postby jam007 » Mon May 29, 2017 11:26 am

I think it looks like it's "floating" up in the air just as the nose is raised. Yes. hard to tell.
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Re: DHC-6 Twin Otter development

Postby wkitty42 » Tue May 30, 2017 3:12 am

one thing that i noticed was that the pilot kept the yoke pushed forward to keep the nose on the ground for better steering control... once he hit speed, he eased back and the craft practically jumped into the air...
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."
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Re: DHC-6 Twin Otter development

Postby erik » Tue May 30, 2017 6:19 am

Now that you mention it: good observation.
I know from the wind tunnel data that the aircraft has a propeller induced pitching moment due to increased airflow over horizontal stabilizer.

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Re: DHC-6 Twin Otter development

Postby nuno.seletti » Sat Jul 08, 2017 3:48 pm

Image Hello! why my cockpit is like this? :cry: I can't see the runway from the cockpit, so iy's bad to pilot from the exterior view :lol:

Someone can help me? thanks!
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Re: DHC-6 Twin Otter development

Postby nuno.seletti » Sat Jul 08, 2017 3:52 pm

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Re: DHC-6 Twin Otter development

Postby wlbragg » Sat Jul 08, 2017 6:18 pm

First, why did you download it from there?
Where is that googledrive link from?
Why don't you try the one that comes with FlightGear?
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Re: DHC-6 Twin Otter development

Postby dg-505 » Sat Jul 08, 2017 6:52 pm

nuno.seletti wrote in Sat Jul 08, 2017 3:52 pm:https://drive.google.com/file/d/0B2wA-loaS2xnVkgwblpGbXpMVVk/view?usp=sharing


This looks like one of the Google Drive links that we used before there was a git or svn repo, but this is really outdated!

Try downloading it from this link:
http://fgfs.goneabitbursar.com/official/dhc6.zip
This should be the current version
It's not just a hobby. I'ts a passion: FLYING !!

DHC-6 Twin Otter development
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Re: DHC-6 Twin Otter development

Postby nuno.seletti » Mon Jul 10, 2017 11:52 am

wlbragg wrote in Sat Jul 08, 2017 6:18 pm:First, why did you download it from there?
Where is that googledrive link from?
Why don't you try the one that comes with FlightGear?


Hello! It's because i have search some link to download it in this topic, at every page and test it, but i have always this strange blank cockpit, and the dhc 6 that we can download in flightgear wiki but i have the same problem. :cry:
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Re: DHC-6 Twin Otter development

Postby nuno.seletti » Mon Jul 10, 2017 11:53 am

dg-505 wrote in Sat Jul 08, 2017 6:52 pm:
nuno.seletti wrote in Sat Jul 08, 2017 3:52 pm:https://drive.google.com/file/d/0B2wA-loaS2xnVkgwblpGbXpMVVk/view?usp=sharing


This looks like one of the Google Drive links that we used before there was a git or svn repo, but this is really outdated!

Try downloading it from this link:
http://fgfs.goneabitbursar.com/official/dhc6.zip
This should be the current version


Thanks for help men! :D I must test it, i tell you when it's work good 8)
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Re: DHC-6 Twin Otter development

Postby nuno.seletti » Wed Jul 12, 2017 12:46 am

Sorry but I have the same problèm :cry:
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Re: DHC-6 Twin Otter development

Postby asr » Wed Jul 12, 2017 10:46 am

nuno.seletti wrote in Wed Jul 12, 2017 12:46 am:Sorry but I have the same problèm :cry:

Have you played a little bit with the rendering settings? Maybe disable `rembrandt` or `ALS`
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Re: DHC-6 Twin Otter development

Postby dg-505 » Wed Jul 12, 2017 1:33 pm

Is there the possibility that you can update your FlightGear to the current version?

The Twin Otter has some features implementet which only work with newer FlightGear versions. These features make the aircraft incompatible with older versions.
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