Posted on 12 Comments

Almost there

The new FDE is now “almost finished” – which really means that we are now in the kingdom of Pareto and Murphy. The final stage of any project is inevitably where most of the work is being done, and where everything inevitably goes wrong. That said, I am actually optimistic about releasing 4.1b2 within the next few weeks.

The big difference between the previous (current) version of the Draken FDE and this attempt is that I am now starting with a blank sheet and some good books on aerodynamics, instead of just tweaking a stock FDE until it squeaks. The 4.0 FDE performs OK within, say, 75% of the envelope. The new version will hopefully be able to “touch the edges”.

I started by remodeling the engine, which now produces net dry thrust within 5% of the real thing all the way from the runway to the “coffin corner”. It also has the correct thrust-specific fuel consumption and a more linear throttle response. All based on the sparse documentation from Rolls-Royce, Volvo and Saab that I managed to find.

The next step was to rework the lift and drag parameters to achieve the correct airspeed, angle-of-attack, pitching moment, etc. during climb and cruise. A great help in this was that I finally found some actual airfoil data for Draken. At the moment I am working on stability and control derivatives, which turned out to be the trickiest part. I don’t have the real values, so it is basically a lot of maths, guesswork, and test flights.

Putting the final touches on the derivatives today, then adding the afterburner and starting on the supersonic parts.


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12 thoughts on “Almost there

  1. I am glad to hear that your work is going forward! The new models for Engine and Flight Dynamics sound very interesting. I will download it as soon as you release the Beta version. But, do not hurry, make it in your own tempo.

  2. Tom, thank you for all the work you are doing on the Draken. Any chance 4.1b2 will come without the version text block floating above the aircraft?

    cheers, Henk.

  3. Hi Henk!
    The banner in the beta versions is there for a reason. All versions of Draken have at some point been leeched by ad-driven “flightsim” websites. Some even repackaged the FS9 version and tried to hawk it as “Draken for FSX” before we had released an FSX version. Amazing. As the downloads are freely available there is very little I can do to prevent leeching, but I can at least prevent people from distributing test versions as the real deal. Hence the banner.

  4. Thanks for explaining, I fully understand your frustration – just saw a recent upload of your work on Simviation by an individual called Mohammad Faali (573 downloads already, at least he mentiones it is from Bookmark).

  5. Watching closely this site and looking forward to each progress…with your Draken, Jurcagas MiG-21 and SSW f-104 my holy trinity is complete :) keep up the good work!

  6. Thanks for the heads up, Henk. I have contacted Simviation and asked them to remove the upload, although they have not been very responsive in the past. The leeched FS9 file that I mentioned is still on Simviation, five years later.

  7. This is a fantastic news! About the afterburner have you fund a solution?

  8. Thomas, I’ve been flying your Draken’s since FS9 and the last FSX version and following this project. My question is, will the final FSX version have the control stick fully modeled/visible?

  9. I have started modeling the stick, but I am not certain it will be included for the 4.1 release. Depends on how much time I have to spend on it, it is quite tricky to model. I don’t want it to be a showstopper, so if everything else is finished I will probably leave it out.

  10. Just an opinion, but to leave out the stick detracts from the model overall. in the previous version, it’s like a hole in the cockpit. I hope you are able to include it.

  11. Hi Thomas! Will the new FDE make it able to perform the Cobra manouvre? I haven’t been able to pull it off, so I guess it’s not possible right now.
    Also, just my opinion, but I really think it would be great if you try to include the control stick, the cockpit feels kind of empty without it.
    Anyways, keep up the good work!! :)

  12. Well, the “Cobra” is disputed regarding Draken, but yes, being able to pull up sharply and “stand on your tail” is one of the major differences between the old FDE and the new one. I used to advertise this maneouvre in the Flight Manual, but as you point out it can not be done with the present FDE. So I have deleted that paragraph for the moment, as it is not possible. But in the current working version I can indeed pull a Cobra. ;)

    The 4.0 version is quite pleasant to fly, but it behaves like a much bigger aircraft in my opinion. The 4.1 version will be more responsive, and more realistic, which might not be to everyone’s liking. But there you are. I am trying to find a balance between realism and “sense of wonder”.

    The stick will be included in the 4.1 release since so many people have been asking for it, but there will be a switch to show/hide it as it will partly obscure vital parts of the instrument panel.

    I hope this answered your questions in some degree.
    Thanks for your support!

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