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Alouette III overhaul

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Re: Alouette III overhaul

Postby LesterBoffo » Tue Nov 21, 2017 3:57 am

My version is really old it keeps telling me in red text that my version of FG is older than 3.1, ( it's 2016 .1.1.. :roll: ) It starts OK but the autostart needs to be assisted by turning on the starter and fuel pump and I can't get it airborne without it getting a fatal tail strike.
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Re: Alouette III overhaul

Postby Thorsten » Tue Nov 21, 2017 6:18 am

My version is really old it keeps telling me in red text that my version of FG is older than 3.1,


The previous maintainers decided to do an FG version check with lower and upper limits, and if you fail the check, the helicopter gets automatically damaged on liftoff. So it automatically punished you for using a new FG version.

Needless to say, that was one of the first things I removed...

This is odd, as the later AS Lama was famous for setting altitude records, and the Alouette III shouldn't be that far down on power in comparison.


Wikipedia says the service ceiling is 3.200 m (whereas the Lama is quoted with 5400 m), which doesn't sound that high. The hover ceiling must be somewhat lower, so... it seems to fit together.

The above can be discarded, sorry.


I haven't looked much into helicopter FDM, but I'm not sure I understand - I expected JSBSim wants a formality to be done (i.e. a bracket of <function> tags needs to be put somewhere for consistent coding) - this sounds like you observed an actual change in performance?
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Re: Alouette III overhaul

Postby lzu164 » Tue Nov 21, 2017 7:36 am

Thorsten wrote in Tue Nov 21, 2017 6:18 am:
The above can be discarded, sorry.


I haven't looked much into helicopter FDM, but I'm not sure I understand - I expected JSBSim wants a formality to be done (i.e. a bracket of <function> tags needs to be put somewhere for consistent coding) - this sounds like you observed an actual change in performance?


Yes, at least I think so :D . After changing the code, I was able to get with max collective from sea level to 6000-7000ft at steady 60kn forward speed, and vertical speed was almost 2000ft/min. Without modifications I couldn't get much above 4000ft, and even that required pitching up and coming into hover. Vertical speed was about 1000ft/min. I tried this a couple of times and got the same behavior every time I changed the code.

I don't really know how a it should behave, and I'm a complete noob on fdm:s, but official specifications for 4630lb weight (pretty similar to the model) give hover ceiling as 4265ft and rate of climb of 1040ft/min.
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Re: Alouette III overhaul

Postby bugman » Tue Nov 21, 2017 8:09 am

Due to these developments, I will split the wiki article into two:


These article titles can be renamed as desired. I will also convert these to the new {{infobox aircraft}} template, and use the {{for}} template to cross-link the articles. The two articles will then show up in these two categories:


Regards,
Edward

EDIT: Improved the wiki links.

EDIT 2: The wiki page has now been split. Thorsten and the pseudo-person called Josh/Gérard/Robin/ghmalau/Ahmad/hohorange/dilse2ahmad/GR family/Daniela/David/Youcef/GRTux/eekpo, please feel free to update your articles as you see fit.
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Re: Alouette III overhaul

Postby bugman » Tue Nov 21, 2017 9:00 am

@Thorsten: What about renaming Alouette-III_sc-set.xml to Alouette-III-set.xml? Then the FGAddon hangar and GRTux hangar versions would no longer clash.

Regards,
Edward
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Re: Alouette III overhaul

Postby wkitty42 » Tue Nov 21, 2017 9:41 am

FWIW: i was testing a KRDU out back in the GA parking area ;)
"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: Alouette III overhaul

Postby Thorsten » Tue Nov 21, 2017 10:29 am

@Thorsten: What about renaming Alouette-III_sc-set.xml to Alouette-III-set.xml? Then the FGAddon hangar and GRTux hangar versions would no longer clash.


Good idea - will do.
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Re: Alouette III overhaul

Postby StuartC » Tue Nov 21, 2017 11:17 am

you need to rename the model xml otherwise FG can get confused and load the wrong model if you have both versions installed. This has happened to me while working on a new version of an aircraft while still having the old one in my FG. No changes were showing and it was because it was loading the model v from the other folder and version, not the one I was actually loading. Set files + folders were different, model xml's were named the same.
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Re: Alouette III overhaul

Postby wkitty42 » Tue Nov 21, 2017 11:46 am

this problem should be taken care... i've been running with the FGAddon c172p and the repo of it and have not had FG pull from the wrong one since way back in the 2016.* versions... in fact, i have several craft that i have FGAddon and dev repo versions of and i've just not seen this in a long time...

@StuartC: if you are seeing this, maybe it is a problem with that FG v2.12 version your profile says you are (still) running??
"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: Alouette III overhaul

Postby StuartC » Tue Nov 21, 2017 1:32 pm

I'm running 2017 3.1, at the moment.
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Re: Alouette III overhaul

Postby LesterBoffo » Tue Nov 21, 2017 4:15 pm

I can't help but think the tables for the engine power with altitude pressure are a bit wonked. They look like they were borrowed from a aircraft turboshaft. The Artouste is a centrifugal compressor turbine, which compared to axial have a pretty good ability to deal with altitude. It should be down on power, but 4K feet ceiling for operation is pretty low.

The table includes a knots to airpressure table incremental increase which would assume there's some sort of power increase with airspeed? (air ram effect.?) the Artouste on this helicopter has no forward facing turbine intake scoops, and like most mid century helicopters was not designed to be flown faster than 100~120 knots. The table has a 200 knot column.

The early 1950's AeroSpatiale Djinn, which used a purely cold air fed reaction powered pair of rotor blades, had excellent high altitude performance. There's movies of it on Youtube landing and taking off in the French Alps at over 10,000 feet, it was powered by a centrifugal TurboMeca Palouste, adapted for cold air pressure production specially for the AS Djinn.

Image

I'll wager it could be started and taken off higher than the engine VC tables allow for.
Last edited by LesterBoffo on Tue Nov 21, 2017 5:19 pm, edited 1 time in total.
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Re: Alouette III overhaul

Postby bugman » Tue Nov 21, 2017 4:23 pm

According to Wikipedia, the SA 316B service ceiling is 3,200 m (10,500 ft).

Regards,
Edward
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Re: Alouette III overhaul

Postby wlbragg » Tue Nov 21, 2017 4:32 pm

was starting up at VQPR which WIki states is at 2,235 m (7,332 ft).

Well then we need a mixture control for it (maybe there is, I didn't look) , because I was at an elevation where it should be able to start.
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Re: Alouette III overhaul

Postby LesterBoffo » Tue Nov 21, 2017 5:05 pm

also from that Wiki...

In June 1960, an Alouette III carrying seven people made take-offs and landings on Mont Blanc in the French Alps at an altitude of 4,810 meters (15,780 feet), an unprecedented altitude for such activities by a helicopter.[7] The same helicopter again demonstrated the type's extraordinary performance in November 1960 by making take-offs and landings with a crew of two and a payload of 250 kg (551 lbs) in the Himalayas at an altitude of 6,004 meters (19,698 feet).[7]
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Re: Alouette III overhaul

Postby LesterBoffo » Tue Nov 21, 2017 5:08 pm

wlbragg wrote in Tue Nov 21, 2017 4:32 pm:Well then we need a mixture control for it (maybe there is, I didn't look) , because I was at an elevation where it should be able to start.


It's a turboshaft engine, not a gasoline recip, and there's no mixture, you just spray in more more JetA into the combustion chamber(s)
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