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737-300 Classic - New and Improved

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737-300 Classic - New and Improved

Postby e-pilot » Fri Aug 16, 2013 4:36 am

Hello all,

I originally started working on this old aircraft just for myself because I wanted a flyable 737-300 classic. Then it became a learning project, then it turned into a custom aircraft project for a VA. With over 2000 hrs of test flying from many happy va pilots I can say that this aircraft is at the least very flyable now.

I am thinking that perhaps others in the fg community might enjoy it as well. I have attempted to contact the original authors to no avail. (I did manage to contact Emmanuel who informed me that he had never worked on the aircraft and did not know why he was listed in the credits)

I certainly don't want to step on any toes so if this aircraft is in serious development by a real developer somewhere, please forgive the intrusion.


Still very much a work in progress, submitted for your review: The Boeing 737-300 Classic - http://www.aesoft.net/temp/737-300.zip
Last edited by e-pilot on Fri Nov 01, 2013 10:51 pm, edited 2 times in total.
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Re: 737-300 Classic - New and Improved

Postby Bravo » Fri Aug 16, 2013 2:13 pm

FG brazil had an independent project also. Theirs has a similar or identical cockpit, gear suspension, and openable doors, but lacks some of the features yours has like the new AP and the callouts. Maybe you guys can get all the good stuff into one model :lol:

Antoni
If you need anything just PM me.
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Re: 737-300 Classic - New and Improved

Postby e-pilot » Mon Aug 19, 2013 4:52 am

We both started with the same cockpit. This one has been developed beyond theirs which last was worked on late 2011. I was going for one that flew well and had a reliable A/P and had an accurate fdm, which I think I have achieved. Other developers, when your done with your commits and merges for the upcoming release, please have a look and any comments would be appreciated.
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Re: 737-300 Classic - New and Improved

Postby Soitanen » Mon Aug 19, 2013 6:43 am

I'm not a aircraft developer, just user, but for me, realistic FDM is at first place.
About your work. At landing it seems to be very fly-able, even at low speed, when hard contact with ground must be (high flare, then craft must hit runway). In you version it slightly moves down. Also (for me) aero drag is low, especially when gears are down. May be I'm not right, but it's my feelings.
Boeing 737-300. Reworked cockpit, FDM, autopilot and much more. WIP.
Boeing 737-800. WIP. Canvas PFD and ND.
Antonov An-24B. Made from scratch. Very good FDM. 3D model by Adrian. WIP.
Project Russia (some cities, based on OSM with custom objects).
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Re: 737-300 Classic - New and Improved

Postby e-pilot » Mon Aug 19, 2013 11:52 pm

Thanks for the ideas Soitanen - I'll have a look at those things
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Re: 737-300 Classic - New and Improved

Postby Honzaku » Wed Aug 21, 2013 8:25 am

It is great to hear someone is improving this legendary classic airliner which is still missing in Flightgear in acceptable quality. In my opinion, I would concentrate the most of the effort in the system developments, avionics and cockpit 3D. The lack of these points is the biggest issue on this particular plane and makes the flying of it very unpleasant and difficult. On the other hand I would leave the FDM as it is, at least for the beginning, since the FDM has been made by David Culp, who is one of the developers of JSBSim, has degree in aeronautical engineering and is also real life pilot who has spent many hours on B737. So he probably knew very well what he was doing when he was writing FDM and I am not sure If there is currently anybody else who has enough of information and know-how to significantly improve the FDM. But the plane desperately calls for some decent 3D cockpit, systems and working instrumentation on the level of quality of B 777 or even Tu 154 which, first of all, would make it finally flyable.

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Re: 737-300 Classic - New and Improved

Postby Soitanen » Sat Aug 24, 2013 5:55 am

Honzaku, I disagree with you about FDM. Original by David Culp have the same unrealistic behavior on landings - too high stability on very high angle of attack and too low drag with full flaps and gear down... I can fly around 110 kts on idle with nose up and do not touch the runway. So FDM needs to be overlooked. Good question is where to find proper good data? But I don't know about it at this moments (I'm interested in good 737, so I'm looking for data).
Boeing 737-300. Reworked cockpit, FDM, autopilot and much more. WIP.
Boeing 737-800. WIP. Canvas PFD and ND.
Antonov An-24B. Made from scratch. Very good FDM. 3D model by Adrian. WIP.
Project Russia (some cities, based on OSM with custom objects).
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Re: 737-300 Classic - New and Improved

Postby Pierre.Mueller » Sat Aug 24, 2013 12:40 pm

Soitanen wrote in Sat Aug 24, 2013 5:55 am:Honzaku, I disagree with you about FDM. Original by David Culp have the same unrealistic behavior on landings - too high stability on very high angle of attack and too low drag with full flaps and gear down... I can fly around 110 kts on idle with nose up and do not touch the runway. So FDM needs to be overlooked. Good question is where to find proper good data? But I don't know about it at this moments (I'm interested in good 737, so I'm looking for data).


I came back to see how FGFS has developed. Now I stumbled upon this thread.

@e-pilot: I wanted to try your improved aircraft. But I can't see any changes on the fdm. In your download it is actually the same fdm like on FGData and on the Download page.

The FGFS wiki gives by the way names of all the authors who has in any way contributed to the model. Mr. BARANGER has delievered the wheels, Mr. Cunningham the wings etc; etc...

@Soitanen: I have to diasgree.
Have you searched for datas on the net? I don't think so- more below! And have you read the help section on Menu --> Help --> Aircraft help?

It gives you all the Vspeeds at all possible weights!
I think they are based on this very good site: http://www.b737.org.uk/

I have tried some weights and speeds- and indeed they all work in the way I would expect. Vspeeds are very, very important! If an aircraft does not rotate at the specified Vr, it has to be reported to the authorities, and the issue has to be examined! And the vspeeds are correctly simulated on the FGFS 737-300.

So with full flaps, at lowest possible weight (77000lbs/ 35000kg) Vref is 107 knots IAS. Vref is always = stall speed x 1.3! so stall speed would be here around 82 knots.

With full flaps, at MTOW (Maximum Takeoff weight) (143000lbs/ 65000kg) Vref 152 knots. So stall speed would be 116ktn.


More interesting:
When you search for the stall speeds on the net you will find an interesting article on http://www.flightglobal.com: http://www.flightglobal.com/news/articl ... nt-326834/
We don't have the weight here, but we have the body pitch angle, and the Indicated Airspeed: 82 ktn, 44deg pitch up. No Crash! Vref should have been 135ktn, and the crew managed to get the airspeed down to 115 ktn.

So I think 110ktn and pitched up without descending is not unrealistic, btw I could not reproduce your issue. The aircraft is nicely descending and touching the rwy at 110ktn at the lowest possible weight with full flaps.

Long time ago I spoke with an airliner pilot about simulations. He laughed about what many Hoppy-Sim-pilots thinks how an airliner has to fly: Sluggish, very low roll rates, very high stall speeds. All wrong.

Of course they are more sluggish then a small prop. But not so sluggish than a big cruise ship. Especially the 737 can be flown very dynamic.
Airliners are created to fly as safety as possible- and not as difficult as possible!

What the 737-300 needs is a cockpit in the same quality like the 777 or the new 707. Also the systems and autopilot has to work like the original thing. But please, please keep the fdm as it is, unless you have much more exact datas how the real aircraft behaves.

In the moment I can fly the 737-300 from FGData and Download page like the real one (beside the missing cockpit and unrealistic autopilot), and after some investigations I don't see that the aircraft behaves unrealistic. Only the imaginations of some non-flying people here about a realistic flight model is unrealistic! :lol:

Datas:
Why I can say that? I read also this document- the original flight manual with stall speeds, procedures, numbers: http://dream-air.ru/new/pilotam/Boeing_ ... Manual.pdf.

Found easily on Google! ;-)

Say thanks to David Culp, who created the fdm and was a 737-300 pilot and is a studied aeronautical engineer. So I'm very very sure, that he knew what he did! :wink:

I hope it helps

Greetings from switzerland
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Re: 737-300 Classic - New and Improved

Postby daveculp » Sat Aug 24, 2013 6:27 pm

Hello everyone,

I'm happy to see this old model get some updates. It was originally started by Innis Cunningham, IIRC. I did the FDM, and was at the same time writing AeroMatic. The FDM was meant to be both a 737-300 model and a template for the AeroMatic airliners category. ( Yes, airliners all fly pretty much alike, at least the fly-by-cable ones. Any performance differences are due mostly to weight and power). I was amazed at how well it flew with so few data points. If you want to add some data points, here are some that *might* make a noticeable difference:

1. Separate the slat and flap effects, which will probably require 3D tables.

2. Add some data points to model extreme conditions (a.k.a. "Stupid pilot tricks")

That's about it. I don't have much time to spend on flight sims these days, but feel free to ask me about the FDM or 737-300/500. I think the last time I flew one was in 2008, but I remember a little bit.
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Re: 737-300 Classic - New and Improved

Postby Soitanen » Sat Aug 24, 2013 7:16 pm

Thanks for answers. I will investigate more.

David, is there big difference in FDM (how pilot feels) between 733 and 735?
Boeing 737-300. Reworked cockpit, FDM, autopilot and much more. WIP.
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Re: 737-300 Classic - New and Improved

Postby daveculp » Sat Aug 24, 2013 7:50 pm

Soitnanen - No, the 737-300 and -500 fly identically.
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Re: 737-300 Classic - New and Improved

Postby buster » Fri Oct 18, 2013 7:22 pm

Hi e-pilot,

I think it'as a good idea to make a redesign of the 737-300, because I liked the FDM but it's cockpit still
has been very simple.
To get it more attractive I designed a nice working autopilot for you 737-300.
I have several experiences in design of autopilots as I designed the AP for the 747-400 and for the
new 707 from D-MKF1.
I would like to see my AP also integrated in your 737-300.
You can download it from http://flightgear.azuana.de/737-300-autopilot.tar
it contains 3 files,: '737-300/System/autopilot.xml', '737-300/Nasal/autopilot-routemanager.nas' and
'737-300/737-300-set.xml'. The file '737-300-set.xml' is only added to demonstrate the inclusion of the other two
other files. You need to include both of them to get the AP working.

Of cause it's your own decision if you want to use it, it's just an offer of mine.
So I hope you will continue you work, bye,
Markus
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Re: 737-300 Classic - New and Improved

Postby e-pilot » Thu Oct 31, 2013 5:35 am

Thank you very much for the offer Markus - I will, of course, take a serious look at what you have done. The A/P was one of the first things I began work on when I started and have developed 4 completely different versions since then. The latest was created with the best flight control characteristics developed so far but also tied in to work with the now completely functional clickable MCP (A/P Panel) in the cockpit.

Just to let everyone know I have been uploading very regular updates at the original link address. Usually one a day. The current version is far further along than when I originally started this thread. Still a ways to go but getting closer! Enjoy!
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Re: 737-300 Classic - New and Improved

Postby zakalawe » Thu Oct 31, 2013 2:24 pm

e-pilot wrote in Thu Oct 31, 2013 5:35 am:Just to let everyone know I have been uploading very regular updates at the original link address. Usually one a day. The current version is far further along than when I originally started this thread. Still a ways to go but getting closer! Enjoy!

I'm delighted by this, can we get your work into fgdata? As discussed on IRC the new in fgdata 757 needs Canvas-based EADI and EHSI displays, I'm hoping to hack something up in the next few days since FSWeekend is no place for doing serious C++ coding. From my reading the 737 Classics EADI and EHSI is 98% identical to the 757/767 config, so hopefully we can integrate these. (First I need to improve my skills at using Inkscape!)

Gijs's work on the 747-400 EICAS pages (again using the Canvas) hopefully gives some ways to implement the engine display module too.
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Re: 737-300 Classic - New and Improved

Postby e-pilot » Thu Oct 31, 2013 9:07 pm

The EADI and the EHSI in the 300 are in very poor shape - I have only minimally started improving them. In fact they are so bad right now I have been looking for replacements but haven't found a suitable candidate yet. Would be terrific if you get the 757's working well. Might be a candidate for a replacement for the 733.
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