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Dassault Mirage 2000 H08 (2007 Version) update

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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby openflight » Sun Jun 07, 2020 3:33 am

The original Mirage 2000 lands at a flat attitude, attempts to make the plane descend nose high were futile, the Mirage 2000 would descend power off at about 140 knots but any addition of power to bring up the speed would result in a climb.

I used instead the configuration file from the Mirage III in this case a YASIM configuration file that worked very well, with a high A0A approach and aerobraking on landing. Using the unmodified Mirage file with a lesser powered engine made for a slow take off and interesting approach, not to mention the roll off at low speeds, but overall a very nice experience. I printed out the YASIM file to have a look, hopefully I can have good ground interactions as well, as well as accurate stall behaviour.
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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby openflight » Mon Jun 08, 2020 3:34 am

Changing the settings in YASIM to the sweep angle of 58 degrees gives an error in YASIM, unable to converge on a solution after 1000 iterations or something like that.


Code: Select all
<wing x="-1.991" y="0.247" z="-0.683"
       chord="7.352"
        length="4.96"
        taper="0.09"
         sweep="58"
        camber="0.05">
        <stall aoa="20" width="1" peak="1.2"/>
        <flap0 start="0.59" end="0.90" lift="1.5" drag="1.4"/>
        <spoiler start="0.59" end="0.90"  lift="1" drag="39.9"/>


I am not sure why the chord is listed as 7.352
because in my calculations chord is in feet, and is about 14 ft, length of the wing (root to tip) is about 7 ft. There is no way to get a 400 sq ft wing with a 7ft chord, unless chord is in metres.
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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby enrogue » Mon Jun 08, 2020 7:31 am

yes - YASim is in metres
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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby openflight » Mon Jun 08, 2020 8:41 am

Ok but then I cannot have a wing sweep of 60?
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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby enrogue » Mon Jun 08, 2020 7:44 pm

Do you mean 60 at the leading edge? Because that’s not how yasim does sweep - it should be at 50% chord of the element you are defining from memory

Are you using the blender yasim import to visualise your model?
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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby openflight » Tue Jun 09, 2020 2:01 am

Yes 60 degrees leading edge - Dassault states that is it 58 degrees. Let's see YASIM. So anyway this is measured from mid chord to mid chord of the tip?

http://wiki.flightgear.org/YASim

sweep: The sweep angle of the wing, in degrees. Zero is no sweep, positive angles are swept back. Defaults to zero.


I also need this: the aircraft initiates a roll too quickly, as if the wing had zero weight. I have been watching videos of the Mirage 2000 and while it rolls fast, the start of the roll is slightly delayed.

Ballast
This is a mechanism for modifying the mass distribution of the aircraft. A ballast setting specifies that a particular amount of the empty weight of the aircraft must be placed at a given location. The remaining non-ballast weight will be distributed "intelligently" across the fuselage and wing objects. Note again: this does NOT change the empty weight of the aircraft.
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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby enrogue » Tue Jun 09, 2020 7:55 am

aside from the fact that the m2000 has fly by wire, in YASim there is a control-speed factor which gives the time taken for the surface to move from one side to the other

I would have a look at http://www.buckarooshangar.com/flightgear/yasimtut.html
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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby WoodSTokk » Tue Jun 09, 2020 9:01 am

Try to set the tank around 1/3 or 1/2 of the wing.
The weight of the fuel and distance to the CoG rise the inertia and slow down the roll speed.
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Re: Dassault Mirage 2000 H08 ( Version) update

Postby openflight » Wed Jun 10, 2020 12:08 pm

Will try that, and the tutorial helped.

After a few close calls flying the Mirage 2000 and probably would have ejected in the real thing, I realize I need some flying training in a training plane. Looking at the PC-7 and the Alpha Jet, then at some air force training programs and need to then get trained. It is difficult to evaluate an aircraft which I cannot fly properly in its mission or without being able to make a decent approach in the first place.

UPDATE:

https://bootcampmilitaryfitnessinstitut ... agrams.pdf

https://www.flying-start.org/military-f ... air-force/

Time for a wish list for the Mirage:

    Replace Pilot
    3D panel and instruments
    Solid canopy arch
    Smoothen wing and surfaces
    Replace canopy
    Aircraft tires must touch runway
    Tires need to be more realistic
    Engine change to M53
    Realistic roll - in and roll - out
    Appearance of inertia to aircraft
    Textured non working cockpit areas
    Landing gear compression
    Elevon movement to near zero in 3d model, Elevon full movement when rolling - all elevons are involved
    Remove rudder movement with nosewheel steering
    Realistic fuel
Last edited by openflight on Wed Jun 10, 2020 1:19 pm, edited 2 times in total.
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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby legoboyvdlp » Wed Jun 10, 2020 12:14 pm

I must admit it seems like a bit of a waste of effort to make an aircraft which already exists, unless I misunderstood what you are doing?


openflight wrote in Sun Jun 07, 2020 3:33 am:The original Mirage 2000 lands at a flat attitude, attempts to make the plane descend nose high were futile, the Mirage 2000 would descend power off at about 140 knots but any addition of power to bring up the speed would result in a climb.
I printed out the YASIM file to have a look, hopefully I can have good ground interactions as well, as well as accurate stall behaviour.


Accuracy in yasim is quite simply impossible.

There is a openVSP-generated JSBSim Mirage 2000 which already has months of work in it and has solved all these issues you mention.
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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby enrogue » Wed Jun 10, 2020 12:33 pm

Yasim doesn't accurately do delta wings, so the mirage 2000 may not be the best for learning (plus as lego has stated there is a very capable one done already)

But I think your need is to learn - which yasim is good for - but also to have an aircraft that runs on low spec hardware (which the M2000-5 doesn't)

There are literally tons of aircraft with basic YASim FDM created by helijah crying out for adoption - take a look at the recently released F11F Tiger for instance
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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby openflight » Thu Jun 11, 2020 4:52 am

Are you using the blender yasim import to visualise your model?


Not yet, would be nice to see the horizontal stabilizer
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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby openflight » Thu Jun 11, 2020 5:01 am

legoboyvdlp wrote in Wed Jun 10, 2020 12:14 pm:I must admit it seems like a bit of a waste of effort to make an aircraft which already exists, unless I misunderstood what you are doing?


openflight wrote in Sun Jun 07, 2020 3:33 am:The original Mirage 2000 lands at a flat attitude, attempts to make the plane descend nose high were futile, the Mirage 2000 would descend power off at about 140 knots but any addition of power to bring up the speed would result in a climb.
I printed out the YASIM file to have a look, hopefully I can have good ground interactions as well, as well as accurate stall behaviour.


Accuracy in yasim is quite simply impossible.

There is a openVSP-generated JSBSim Mirage 2000 which already has months of work in it and has solved all these issues you mention.


YASIM is ok for now, except for some strange cartoon-like roll effects. I hope I can get the thing to touch the ground at least.

Yes, there is a newer Mirage 2000, but for the following reasons I am not using that :

- I am using Flight Gear 1.0 which works fine on my computer right now
- I have installed FG 2018, but it takes a while to load, not convenient for viewing frequent changes on the model
- The Mirage 2000 on FG 2018 works, but frame rates are low and I ran off the runway before the nose came up for take-off, also with the canopy open. Should have used the 'prepare for flight' as ell as 'autostart'
- The smaller, simpler model and folder structure of the Mirage 2000 '07 model is very convenient and easy to use for my minimalist approach
- I hope to improve the model and host it separately, I have obtained permission from original author.
- Last, but not least, it is a good learning experience - YASIM, 3D modelling improvements etc.
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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby openflight » Thu Jun 11, 2020 5:04 am

enrogue wrote in Wed Jun 10, 2020 12:33 pm:Yasim doesn't accurately do delta wings, so the mirage 2000 may not be the best for learning (plus as lego has stated there is a very capable one done already)

But I think your need is to learn - which yasim is good for - but also to have an aircraft that runs on low spec hardware (which the M2000-5 doesn't)

There are literally tons of aircraft with basic YASim FDM created by helijah crying out for adoption - take a look at the recently released F11F Tiger for instance


I need to learn and experiment, I must admit it is a lot of fun already.

Why no flying wings in YASIM? Is there no attempt in recent updates to include it?
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Re: Dassault Mirage 2000 H08 (2007 Version) update

Postby enrogue » Thu Jun 11, 2020 8:29 am

I suspect flying wings haven't been done because replacing the current trim solution is harder than it looks - it currently tries to solve the trim setting for the tailplane so it can get the lowest drag at cruise.

There have been updates to it recently (in the last couple of years) - jsb added variable incidence to the tailplane among other things.
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