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DHC-6 Twin Otter development

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Re: DHC-6 Twin Otter development

Postby tdammers » Fri Feb 23, 2018 7:58 am

Question about the intake deflectors here: I understand that extending intake deflectors requires sufficient bleed air pressure, which is achieved by spinning the engines up to 80% turbine RPM. Problem is, this required pushing the throttle to near 100%, and the aircraft starts moving, even with the parking brake applied. Feathering the props helps a little, but nowhere near enough. By the time the intake deflectors are fully extended, I may already have crashed into something, driven off the taxiway / runway, or damaged the engine due to high RPM while on grass. Considering this, spawning at a grass airfield is highly problematic, I have to start at an airport with asphalt runways or at least an asphalt apron, and then fly over to the grass field, extend intake deflectors during approach, and not shut down before taking off again.

So is this behavior consistent with real Twin Otters? If so, how do people start up on grass fields with real Twin Otters? Is there some sort of trick to this that I'm not aware of? Or is this something that needs changing in the simulation?
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Re: DHC-6 Twin Otter development

Postby dg-505 » Fri Feb 23, 2018 1:58 pm

Hi tdammers,

according to line 57 and 62 in Nasal/failures.nas as long as the turbine rpm is lower than 85 percent the engine cannot get damaged so it shouldn't be a problem when you are on grass and the turbine rpm is between 80 and 85 percent.

I can't test it right now, but if I remember correctly the aircraft doesn't start to move when the propellers are feathered and the turbine rpm is at 80 percent.

Hope this helps
Jonathan
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 tdammers » Mon Apr 23, 2018 7:54 am

Quick heads up; this weekend at the EDDF ATC event, jomo said that my DHC-6 showed up without a nose cone on his setup, so I investigated a little.

Here's the relevant post: viewtopic.php?f=10&t=13009&p=331259#p331259

In a nutshell, it looks like there can be situations where the "blunt-nose" property doesn't get transmitted correctly, and this leads to neither of the nose cone options being selected. I don't know how to fix this properly, but the change I suggested in that thread (turning one of the "if property is 0, then select this nose" conditions into "if property is not 1, then select this nose") is a good one anyway IMO.
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Re: DHC-6 Twin Otter development

Postby scarymovie » Tue May 29, 2018 5:36 am

scarymovie wrote in Sat Nov 25, 2017 4:42 am:Hi,

I realized that the landing lights and taxi light do not work/visible. Am I doing anything wrong?

Thank you.


The lights issue is still not fixed. Is there anything I can do?

Thanks.
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Re: DHC-6 Twin Otter development

Postby danten66 » Fri Jun 01, 2018 7:54 pm

Is there a way from the panel to switch the NAV1 Slave for the GPS unit on and off? Or is it only through the Equipment - GPS Settings Menu?

Dan
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Re: DHC-6 Twin Otter development

Postby SuspiciousScript » Tue Sep 11, 2018 5:59 pm

I'm having an unusual issue where the radio displays aren't working, despite all the radios being on. I'm on Flightgear 2018.2.2 on a MacBook Pro. I've attached some screenshots for clarification. Is this a known issue, and is there a fix?

Radio displays non-functional
Image

Graphics settings
Image

Thanks!
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Re: DHC-6 Twin Otter development

Postby Darkriser » Wed Sep 12, 2018 7:58 am

Did you turn on this switch?
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Re: DHC-6 Twin Otter development

Postby SuspiciousScript » Wed Sep 12, 2018 12:05 pm

Yup; I tried using autostart to make sure I hadn't missed anything, and the issue remains. All the other avionics work fine.

EDIT: Nevermind, I found the knob! It was the "CO PLT RADIO & V/A PNL LTS" knob on the overhead panel, copilot side.
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Re: DHC-6 Twin Otter development

Postby legoboyvdlp » Tue Nov 27, 2018 4:44 pm

I am having problems - after I start the first engine, RAM useage quickly increases to over 4GB before my computer starts swapping and ultimately freezes. This does not occur on any other aircraft?

Furthermore, in Fuel.xml there are <products> on line 14 and 32 with only one argument (the new error checking in jsbsim picked these up).
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Re: DHC-6 Twin Otter development

Postby Darkriser » Wed Nov 28, 2018 12:14 pm

I do fly Otter on my HP Elitebook ntb. with 4GB RAM and never experienced such a memory increase.
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Re: DHC-6 Twin Otter development

Postby tdammers » Wed Nov 28, 2018 12:52 pm

legoboyvdlp wrote in Tue Nov 27, 2018 4:44 pm:I am having problems - after I start the first engine, RAM useage quickly increases to over 4GB before my computer starts swapping and ultimately freezes. This does not occur on any other aircraft?

Furthermore, in Fuel.xml there are <products> on line 14 and 32 with only one argument (the new error checking in jsbsim picked these up).


I fly this model a lot, and I've never seen this happening. I have poked around in its internals a bit though, and one thing that I suspect might be the cause of this is engine failures due to debris intake - when the engine eats dirt, the nasal code enters an infinite an unstoppable loop to make sure the engine remains broken - I believe this could, at least in theory, just keep racking up memory allocations faster than the nasal GC can clean up.

For this to happen, you'd have to start up on gras or dirt though, and rev up the engine quite a bit though - at idle thrust, the props don't stir up enough debris to cause any damage.
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Re: DHC-6 Twin Otter development

Postby legoboyvdlp » Wed Nov 28, 2018 1:18 pm

Hmm - yes, I was starting on sand.

An infinite loop is definitely not good practice and should be removed.
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Re: DHC-6 Twin Otter development

Postby tdammers » Wed Nov 28, 2018 2:29 pm

legoboyvdlp wrote in Wed Nov 28, 2018 1:18 pm:Hmm - yes, I was starting on sand.

An infinite loop is definitely not good practice and should be removed.


It's not an infinite loop like `while (true)`, but rather a function that unconditionally installs a timeout on itself on exit. So it doesn't max out the CPU, but it might still be enough to hog a lot of memory before the GC gets to it.

I've been meaning to take that awful bit of code out, but haven't gotten around to it - if only because having to quit FG and restart instead of clicking a magical "repair" button is completely stupid.
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