Board index FlightGear Development Aircraft

P-51D stall and spin: make it milder at takeoff and landing  Topic is solved

Questions and discussion about creating aircraft. Flight dynamics, 3d models, cockpits, systems, animation, textures.

Re: P-51D stall and spin: make it milder at takeoff and land

Postby dany93 » Sun Dec 27, 2015 3:22 pm

Interesting.
Thanks, Erik.
dany93
 
Posts: 785
Joined: Mon Sep 07, 2009 3:43 pm
Location: France (Paris region)
Version: 2020.2.0
OS: Linux Mint 18 (64 b)

Re: P-51D stall and spin: make it milder at takeoff and land

Postby kjd.nc » Mon Dec 28, 2015 11:51 pm

Looks like I'll be due to refresh the model soon. Glad to see the activity.

Anybody know where the comm radio volume is? I haven't been able to find a control either visually in the cockpit, or by searching the XML and NAS files. The only way I've found to set it has been to use the property browser to set /instrumentation/comm/volume.

<edited -- The silly pilot had the headset plugged in but not installed over ears. I can hear it now, I just don't have a good adjustment. />
kjd.nc
 
Posts: 72
Joined: Sat Nov 07, 2015 3:45 pm
Location: NC, USA
Version: 3.4
OS: MacOS 10.11.1

Re: P-51D stall and spin: make it milder at takeoff and land

Postby dany93 » Wed Feb 03, 2016 3:16 pm

Would it be possible to include these changes (this version P51D-dany-20151215.7z) in SVN ?
After that in the main repository version, before the V. 2016.1 release?

With the current one in the main rep the engine does not start, and it is excessively difficult to take off and landing.
dany93
 
Posts: 785
Joined: Mon Sep 07, 2009 3:43 pm
Location: France (Paris region)
Version: 2020.2.0
OS: Linux Mint 18 (64 b)

Re: P-51D stall and spin: make it milder at takeoff and land

Postby Thorsten » Wed Feb 03, 2016 3:28 pm

Are you sure you don't want the maintainer job and do it yourself ? :mrgreen:
Thorsten
 
Posts: 11921
Joined: Mon Nov 02, 2009 8:33 am

Re: P-51D stall and spin: make it milder at takeoff and land

Postby dany93 » Wed Feb 03, 2016 3:41 pm

I'm afraid this is too much for me.
It should also consist in getting all of Hal's documentation, a US citizen high enough in FG would be better.

Apart from that, I more or less know how to do with Git (github) in ordinary cases but nothing about SVN.

Also, I would prefer that someone checks these changes before possibly merging them.
dany93
 
Posts: 785
Joined: Mon Sep 07, 2009 3:43 pm
Location: France (Paris region)
Version: 2020.2.0
OS: Linux Mint 18 (64 b)

Re: P-51D stall and spin: make it milder at takeoff and land

Postby dany93 » Fri May 20, 2016 10:36 am

I have done tests and observations about the bug which sometimes makes the sim crash at starting the engine or at the beginning of rolling.

dany93 wrote in Sun Dec 27, 2015 2:50 pm:An unpleasant bug remains, known by hvengel but he couldn't succeed to solve it.
http://forum.flightgear.org/viewtopic.p ... 30#p227792
http://forum.flightgear.org/viewtopic.php?f=49&t=24808
viewtopic.php?f=25&t=22657#p205585
When the sim is started with a tail wind, it crashes the sim or throws the aircraft, sometimes at starting of the engine, or when you begin to roll, when the (relative) wind changes from tail to front. If you happen to get it, try with head wind or / and on another runway. Also, avoid increasing the throttle with the parking brake ON.
Sorry and needless to say, fixing this bug is currently well above my knowledge, despite I'm trying to understand the issue.

It happens when (if) the propeller-advance ratio J=V/ND goes through zero.
I have posted a ticket on SourceForge.
dany93
 
Posts: 785
Joined: Mon Sep 07, 2009 3:43 pm
Location: France (Paris region)
Version: 2020.2.0
OS: Linux Mint 18 (64 b)

Re: P-51D stall and spin: make it milder at takeoff and land

Postby Thorsten » Fri May 20, 2016 10:40 am

That's a good catch! Congratulations - if that turns out to be the solution, it'll really solve a long-standing issue.
Thorsten
 
Posts: 11921
Joined: Mon Nov 02, 2009 8:33 am

Re: P-51D stall and spin: make it milder at takeoff and land

Postby wlbragg » Fri May 20, 2016 12:24 pm

Outstanding, same trouble (I think) with the JSBSim j3cub. Really happy to finally uncover the cause.
Kansas(2-27-15)/Ohio/Midwest scenery development.
KEQA (2-27-15), 3AU, KRCP Airport Layout
Intel i5 3570K AMDRX480
wlbragg
 
Posts: 5981
Joined: Sat Aug 25, 2012 11:31 pm
Location: Kansas (Tornado Alley), USA
Callsign: WC2020
Version: next
OS: Win10/Linux/AMDRX480

Re: P-51D stall and spin: make it milder at takeoff and land

Postby Bomber » Fri May 20, 2016 12:39 pm

Now I'm sure a couple of years ago I posted up about the prop issues of some plane and why....

Maybe those people so eager to search out posts of mine to slag me off could find this post attempting to explain.
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchel
Bomber
 
Posts: 1933
Joined: Fri Dec 14, 2007 7:06 pm
OS: Windows XP and 10

Re: P-51D stall and spin: make it milder at takeoff and land

Postby erik » Mon May 23, 2016 9:41 am

I've pushed the latest JSBSim code to git.
Bertrand at least fixed on devide-by-zero situation.

Could you try if this helps the P51d?

Erik
erik
 
Posts: 1764
Joined: Thu Nov 01, 2007 1:41 pm

Re: P-51D stall and spin: make it milder at takeoff and land

Postby dany93 » Mon May 23, 2016 10:13 am

Many thanks erik and Bertrand for your reactivity :D
I'll see this.
dany93
 
Posts: 785
Joined: Mon Sep 07, 2009 3:43 pm
Location: France (Paris region)
Version: 2020.2.0
OS: Linux Mint 18 (64 b)

Re: P-51D stall and spin: make it milder at takeoff and land

Postby dany93 » Mon May 23, 2016 2:18 pm

After FG git update: FG 2016.3.0 Revision 013770b3

I don't know... :?

1- At LSGG (Geneva), runway 23, wind 3 kt 150° (=default). J = 0.10 (engine stopped);
I set the wind 0 kt, 150°. Autostart ==> crash :(

Still LSGG, runway 23, wind 3 kt 150° (=default). J = 0.10 (engine stopped);
Autostart ==> J = 0.30 (engine at idle, parking brake ON). OK
Wind 230° (from front) ==> J = 0.34. OK
Wind 50° (from back) ==> J goes down to 0.29 (J does not go through 0), crash :cry:
Reproduced 3 times.

Wind 230° 3kt, Engine stopped : J = 0.042
Wind 50° 3kt, Engine stopped : J = -0.042
Autostart : J = -0.042 (parking brake ON)
Parking brake OFF, slow rolling ==> jostled (yaw, no crash). J = 0.30.

It seems unchanged.

2- At KSFO (runway 28)
No crash at all, by any attempt. :D
Wind at 0 kt (J = -0.05), Autostart ==> OK
Having J going through 0 by any mean: wind reversed, slow rolling (J goes from < 0 to > 0) ==> OK
Observation: J seems "reluctant" to decrease or increase towards 0 and pass through 0.
Seems robust here...

Don't know why he doesn't like LSGG... :?:

Anyway, thank you for your attention.
dany93
 
Posts: 785
Joined: Mon Sep 07, 2009 3:43 pm
Location: France (Paris region)
Version: 2020.2.0
OS: Linux Mint 18 (64 b)

Re: P-51D stall and spin: make it milder at takeoff and land

Postby erik » Mon May 23, 2016 6:07 pm

Bertrand just pushed another small fix which is based on a tailwind test script for the p51d.
You might want tot try again.

Erik
erik
 
Posts: 1764
Joined: Thu Nov 01, 2007 1:41 pm

Re: P-51D stall and spin: make it milder at takeoff and land

Postby bcoconni » Mon May 23, 2016 6:08 pm

Hi Daniel,

I just committed what I hope to be a fix to FlightGear.
Let me know if that fixes the problem.
bcoconni
 
Posts: 41
Joined: Sat Nov 13, 2010 2:27 pm
Location: France
IRC name: Bertrand0
Version: Git
OS: Linux

Re: P-51D stall and spin: make it milder at takeoff and land

Postby dany93 » Mon May 23, 2016 7:30 pm

Yes, I've seen your messages. Thank you.
I'm looking at it.
dany93
 
Posts: 785
Joined: Mon Sep 07, 2009 3:43 pm
Location: France (Paris region)
Version: 2020.2.0
OS: Linux Mint 18 (64 b)

PreviousNext

Return to Aircraft

Who is online

Users browsing this forum: No registered users and 2 guests

cron