Soitanen wrote in Sat Aug 24, 2013 6:55 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!
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!
I hope it helps
Greetings from switzerland
Pierre Mueller