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.

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

Postby dany93 » Tue Dec 15, 2015 6:47 pm

Hello,

I think (I'm not the only one) that the current P51D (p51d_20141227.zip from the main repository, same as from SVN) is too difficult at takeoff and landing. A clean landing with no roll departure is almost impossible.
After observation, my conclusion is that, at these steps (when grazing the ground), the "spin and stall" feature is triggered too brutally, at a too low angle of attack (10 - 11°). Moreover, it remains active when the aircraft touches and is rolling on the ground (with the nose upward).

I propose a more progressive spin departure, starting at a slightly higher AoA. Also, it is totally cancelled when touching the ground, where it has no justification.
I have been as much careful as I could, aiming at not degrading the behaviour in altitude. I absolutely want not to betray the fabulous work done by sadly missed Hal Van Engel.

I have also changed the spiralling propwash effect. This contributes to the aircraft pulling leftwards at acceleration before takeoff. It was initially obtained (if I understand well) by an angular shift of the engine (6° disorientation leftwards) , which is a bit artificial IMOH. Moreover, if it were to counteract the propwash effect, this disorientation should be rightwards. I could not find any mention of it on the real aircraft (??).
I changed it for a propwash action on the vertical tail, which is closer to the real effect.

The aircraft is now much easier at takeoff and landing, we can even get a 3-point landing. I feel that the main general behavior in stall and spin is still present enough, not degraded. I feel that it has not lost its strong, very interesting character. I hope not being wrong.

Less important, I have also exchanged the VSI and Acceleration instruments location, more logic and in accordance with what is seen on many pictures of the dashboard.

I have also included the p51d-autostart patch proposed by efel in this message (Thanks, effel. I hope you don't mind, please tell me otherwise). Without it the engine does not start, even manually.

P51D-dany-20151215 (unzip and just copy the p51d folder which is inside, letting aside the archive title)

Dany
dany93
 
Posts: 766
Joined: Mon Sep 07, 2009 3:43 pm
Location: France (Paris region)
Version: 2018.4.0
OS: Linux Mint 18 (64 b)

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

Postby legoboyvdlp » Tue Dec 15, 2015 6:53 pm

Thank you dany!
It's good news for me -- never got that beast into the air :)
User avatar
legoboyvdlp
 
Posts: 7001
Joined: Sat Jul 26, 2014 1:28 am
Callsign: YV-LEGO
Version: 2018.3.1
OS: Windows 10 HP

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

Postby wkitty42 » Tue Dec 15, 2015 7:24 pm

so this is a replacement for the existing p51d or can it be placed in a custom craft directory so as to not overwrite the original?
"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."
User avatar
wkitty42
 
Posts: 5634
Joined: Fri Feb 20, 2015 3:46 pm
Location: central NC, USA
Callsign: wk42
Version: git next
OS: Kubuntu 14.04.5

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

Postby Hooray » Tue Dec 15, 2015 7:28 pm

Note that the p51d isn't currently being maintained - in fact, hvengel is looking for a maintainer, and would be glad to provide all the data he's got to any successors willing to adopt his baby.
Please don't send support requests by PM, instead post your questions on the forum so that all users can contribute and benefit
Thanks & all the best,
Hooray
Help write next month's newsletter !
pui2canvas | MapStructure | Canvas Development | Programming resources
Hooray
 
Posts: 11329
Joined: Tue Mar 25, 2008 8:40 am

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

Postby dany93 » Tue Dec 15, 2015 11:32 pm

wkitty42 wrote in Tue Dec 15, 2015 7:24 pm:so this is a replacement for the existing p51d or can it be placed in a custom craft directory so as to not overwrite the original?
For me, it is a replacement. With my old P51D, FG would not start at all. No choice. That is why I downloaded the p51d_20141227.zip from the main repository. But the engine of this one would not start (a single-line change could solve the issue, but the p51d-autostart patch proposed by efel provides the autostart as an extra).

Replacement or keeping both is your choice. If you have a version which works, at least keep it somewhere. Do not overwrite. Do not merge.
But you can have both available easily enough by putting them into two separate directories and playing with priorities in the order of FGRun or of your --fg-aircraft= command line. Or, to select it, you can temporarily rename (just changing a character is enough) the directory that you don't want to be seen by the command line.

In fact, I guess that you will prefer and use only one version in the future. Personnaly, I would keep my old one elsewhere and replace it in the directory to test the new one.
dany93
 
Posts: 766
Joined: Mon Sep 07, 2009 3:43 pm
Location: France (Paris region)
Version: 2018.4.0
OS: Linux Mint 18 (64 b)

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

Postby dany93 » Wed Dec 16, 2015 12:09 am

Hooray wrote in Tue Dec 15, 2015 7:28 pm:....hvengel is looking for a maintainer, and would be glad to provide all the data he's got to any successors willing to adopt his baby.
Please fix me. Recently by searching on the Internet for hvengel, I read that he died in january 2015. Very sad. :cry: I'd like that it would be a misunderstanding, but I'm almost sure that's not the case.

Otherwise, I would of course have tried to get into contact with him before uploading these changes.

The changes that I propose are very very small compared to his work in this aircraft. I strongly wish that this aircraft goes on living on FG, but I'm afraid not being able to be a maintainer. I only know very basics about Blender, nothing about things like Rembrandt, I know something about animations but I'm not very good, the same about nasal code.
The only thing on which I have some knowledge is JSBSim FDM. And even here, the P51D's FDM is so sophisticated that I do not dare to change it much, afraid of betraying something that hvengel put in it with good knowledge.
I don't know what to respond... :?
Last edited by dany93 on Wed Dec 16, 2015 12:16 am, edited 2 times in total.
dany93
 
Posts: 766
Joined: Mon Sep 07, 2009 3:43 pm
Location: France (Paris region)
Version: 2018.4.0
OS: Linux Mint 18 (64 b)

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

Postby hamzaalloush » Wed Dec 16, 2015 12:11 am

RIP... was a nice fellow, really sad news....... his aircraft and creations were a product of passion that we all should strive for
hamzaalloush
 
Posts: 632
Joined: Sat Oct 26, 2013 9:31 am
OS: Windows 10

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

Postby legoboyvdlp » Wed Dec 16, 2015 12:37 am

Oh my! Sad news.
User avatar
legoboyvdlp
 
Posts: 7001
Joined: Sat Jul 26, 2014 1:28 am
Callsign: YV-LEGO
Version: 2018.3.1
OS: Windows 10 HP

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

Postby massima » Wed Dec 16, 2015 10:29 am

RIP
User avatar
massima
 
Posts: 227
Joined: Sat Jan 03, 2015 6:48 pm
Location: Italy
Callsign: M-AXX
Version: 2019.1.1
OS: debian testing

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

Postby AndersG » Wed Dec 16, 2015 11:57 am

dany93 wrote in Wed Dec 16, 2015 12:09 am: Please fix me. Recently by searching on the Internet for hvengel, I read that he died in january 2015. Very sad. :cry: I'd like that it would be a misunderstanding, but I'm almost sure that's not the case.


Very sad news, indeed.

dany93 wrote in Wed Dec 16, 2015 12:09 am:The changes that I propose are very very small compared to his work in this aircraft. I strongly wish that this aircraft goes on living on FG, but I'm afraid not being able to be a maintainer. I only know very basics about Blender, nothing about things like Rembrandt, I know something about animations but I'm not very good, the same about nasal code.
The only thing on which I have some knowledge is JSBSim FDM. And even here, the P51D's FDM is so sophisticated that I do not dare to change it much, afraid of betraying something that hvengel put in it with good knowledge.
I don't know what to respond... :?


In my opinion the maintainer does not need to be (though he/she often is) the main driving force behind the development of an aircraft, but can instead be more of a gate keeper that evaluates and merges proposed changes into the aircraft in FGAddon (rather than having such request being left pending at sourceforge, the mailing list or in other channels). I also think that this second instantiation of the maintainer role might be easier to take/handle for aircraft where the maintainer is not the original developer.

I do think, from our earlier interactions, that dany93 would be fully qualified to fill this role for the p51d, should he so want.
Callsign: SE-AG
Aircraft (uhm...): Submarine Scout, Zeppelin NT, ZF Navy free balloon, Nordstern, Hindenburg, Short Empire flying-boat, ZNP-K, North Sea class, MTB T21 class, U.S.S. Monitor, MFI-9B, Type UB I submarine, Gokstad ship, Renault FT.
AndersG
 
Posts: 2441
Joined: Wed Nov 29, 2006 9:20 am
Location: Göteborg, Sweden
Callsign: SE-AG
OS: Debian GNU Linux

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

Postby Thorsten » Wed Dec 16, 2015 12:19 pm

I'll miss Hal - and his (sometimes very pedantic) attention to detail.

The changes that I propose are very very small compared to his work in this aircraft. I strongly wish that this aircraft goes on living on FG, but I'm afraid not being able to be a maintainer.


The fact that you /are/ able to make meaningful changes implies that you're already familiar with the aircraft - that's more than I could say for myself, I've just flown it a few times. And that you care for it.

You're not necessarily expected to continue development at fast pace - just really think of it as maintenance, making small adjustments in case new interesting features come along which you could support, or finding the right people who can do rendering, effects, 3d or animations and talking to them - that's all it really needs. Someone who cares enough to keep it going.

So I second Anders - you should seriously think about it.
Thorsten
 
Posts: 10961
Joined: Mon Nov 02, 2009 8:33 am

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

Postby Hooray » Wed Dec 16, 2015 12:36 pm

Please fix me. Recently by searching on the Internet for hvengel, I read that he died in january 2015. Very sad. :cry: I'd like that it would be a misunderstanding, but I'm almost sure that's not the case.


I am deeply sorry, last I heard from hvengel it was through his family at the end of 2014, they forwarded a request from Hal to me asking me to ensure that his work continues to thrive in FlightGear due to personal matters taking priority - at which point I got in touch with Gijs and Curt to ensure that his work can be picked up and maintained by others - unfortunately, I haven't seen anything materializing from it since then, which is why I forwarded the original request here - unaware of recent events.

However, the original request is legit, i.e. Hal's family does/did offer to provide the corresponding data (drawings, files etc) to anybody willing to pick up his work.

Given the circumstances, it is indeed very unfortunate that we as a community were unable to respond in a more timely fashion to this request, but anybody willing to consider continuing his work, please get in touch via PM so that we can share the corresponding credentials (you should probably be US based due to postal mail).
Please don't send support requests by PM, instead post your questions on the forum so that all users can contribute and benefit
Thanks & all the best,
Hooray
Help write next month's newsletter !
pui2canvas | MapStructure | Canvas Development | Programming resources
Hooray
 
Posts: 11329
Joined: Tue Mar 25, 2008 8:40 am

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

Postby Bomber » Wed Dec 16, 2015 4:16 pm

Can I make a suggestion....

FG has AI wingmen could it be made such that when selecting an AI wingmen one of the call signs for a wingman be assigned Hvengel.

As time goes by this could be set up in such a way as to provide a random callsign to AI wingmen from a list of 'died in service' community members.

regards

Simon
"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: 1934
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 Hooray » Wed Dec 16, 2015 4:41 pm

I was also wondering how we as a community could pay tribute to hvengel, especially given the quality of hvengel's work and the degree of his involvement around here, for many years.

I was thinking more in terms of a dedicated article on the wiki/newsletter - or preferably even on the website, which could also be a good way to look for future maintainers wanting to pick up hvengel's work.

I think this would be a good opportunity for the community to get our act together and honor all the work and time that Hal put into contributing to FlightGear, to hopefully ensure that his work will be continued by others - because he truly cared about the p51d, but also about FlightGear as a whole.

I don't know if hvengel was ever interviewed for the newsletter, but given his involvement in the FlightGear project, it should not be too much work to write an "obituary" honoring hvengel's remarkable involvement.

Another option would be a "hall of fame" feature implemented in fgfs, i.e. using a GUI dialog with some scrolling text to thank those who are no longer involved in the project.


Given the circumstances, I think it would be in Hal's interest to share the corresponding message - so, here's one of the original messages, which I forwarded to Curt and Gijs roughly a year ago:
Hal requested that a new maintainer for the P51D project be found, as Hal will be unable to maintain it from here on out. In his home he has CDs that contain factory blueprints for the aircraft, and he requests that the new maintainer have them (I can send these to them via postal).

He also mentioned that the SVN archive is up-to-date and contains all the latest changes.

Thank you very much.


Anybody considering to take over the p51d should please be aware of what this entails, and that we as a community should be getting our act together under these circumstances, especially should any of you get in touch with hvengel's family.

Personally, my preference/suggestion would be that one of the more senior contributors (Curt?) should get in touch with hvengel's family and to keep the corresponding data until we have found a new maintainer, i.e. as the intermediary, so that we won't have to bother hvengel's family should there be any other community-level issues...
Please don't send support requests by PM, instead post your questions on the forum so that all users can contribute and benefit
Thanks & all the best,
Hooray
Help write next month's newsletter !
pui2canvas | MapStructure | Canvas Development | Programming resources
Hooray
 
Posts: 11329
Joined: Tue Mar 25, 2008 8:40 am

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

Postby Thorsten » Wed Dec 16, 2015 5:39 pm

I think the AI wingman is a nice tribute, but I've always felt that such gestures should come from people who knew the person and made a decision to do something. Not just happen to a user.

In any case, whatever we decide to do, I think it somehow should involve the P-51D. He really lived for that plane.

What about a livery with his name on it - then anyone who wants to pay his respects can select it to fly?
Thorsten
 
Posts: 10961
Joined: Mon Nov 02, 2009 8:33 am

Next

Return to Aircraft

Who is online

Users browsing this forum: D-ECHO and 32 guests