Sunday, 06 September 2015 13:58

Final stretch - Progress update

Hi everyone,

This time we don´t have a new video for you, but things keep progressing nonetheless. We are still targeting a release in 2015 - again this is not a promise, but our very urgent desire. So where are we at?

As you all know, the airplane is almost complete, save for some minor 3D items, like the outboard landing lights, movable cabin doors, a moving ouflowvalve vane, and a few more. The bulk of the documentation is also there, but it needs to be formatted into a nice document.

The biggest chunk is still the FMS. We have the PERFormance part working, maintaining weights, takeoff page, approach page, etc. The RTE page and entry of a lateral route already works (as you could see in the latest videos). We are still missing the VNAV calculation, and the PROGgress calculation (estimating times, fuel usage).

Two weeks ago, Tom Kyler, our lead FMS programmer, spent a week at my place in Germany, so we could crunch down on the VNAV part. We had done a similiar session a few months ago, where we worked on the VNAV climb part, now it was time to do the VNAV PTH and SPD descent. So what is VNAV? In a nutshell, VNAV is the vertical path that the plane takes along the lateral route. The climb, cruise, descent and missed approach phases. VNAV is pretty complicated, as the computations try to predict the vertical profile (a non-linear climb), and the descent (mostly an idle-power descent), provides altitude and speed predictions for the waypoints (therefore changing the lateral route again, due to changing turn radii) and heeding several different types of restrictions.

The climb is "fairly" straightforward: The aircraft will climb with maximum climb power to the cruise altitude. It will, however, change airspeed at least three times, and possibly come up against altitude restrictions that delay the climb. All of this can be changed and modified by the pilot, so we need to take that into account as well.

The descent is almost a climb in reverse, but the goal is now to target a three-dimensional spot in space, again changing speeds and descent regimes, ducking under and levelling off for altitude restrictions, taking into account all sorts of influencing factors (wind, weight, etc.).

We also have to provide steering cues for the autopilot to do the right thing - climb while in the climb phase, level off for altitude restrictions and the cruise altitude, follow a three-dimensional path during the VNAV PTH descent, hitting deceleration segments, etc.

It is absolutely mind-boggling - but we are on a good way to get it right! Tom has actually written the code to identify the E/D (end of descent) point correctly and reliably. It is "the last point before the end of route or route discontinuity with an AT altitude restriction". Try to put that into code. Phew.

We hope to have VNAV in testing by early October. The CRZ page and PROG page are mere matters of coding crunch, adding up mileage, divide by groundspeed, multiply with fuel-flow... that kind of thing. Not trivial, but a piece of cake compared to the LNAV and VNAV computations.

I really hope that many of you will exert the effort to understand and use the VNAV functionality of this aircraft - unlike most real-life pilots, who consider the VNAV button a "magic button" where you "never quite know what the airplane will do". :rolleyes:

That´s it for now - you can expect to see more frequent updates here from now on until we relase.

Cheers, Jan


  • Comment Link Sunday, 31 January 2016 12:19 posted by IXEG

    Coming soon

  • Comment Link Saturday, 30 January 2016 22:08 posted by jan muilwijk

    when is it comes

  • Comment Link Saturday, 12 December 2015 18:35 posted by Jan

    Hi everyone, thanks for the nice words!

    We totally understand that you want this now, or at least for us to tell you the date you will get it. Both is not possible. We are getting closer, but will not release this prematurely.

    A dedicated support forum is already up, feel free to join up and ask whatever you´d like to know about the plane and our progress:

    See you over there!

  • Comment Link Thursday, 10 December 2015 16:32 posted by Capt. Leh


    With all the excitement of the release of your 737, can you PLEASE and I see it has been asked before... When do you expect a "Rough" time frame for its release?

  • Comment Link Monday, 07 December 2015 12:29 posted by Vadim

    Until the end of 2015 remained 25 days and we believe in your promise to release the product this year.

  • Comment Link Monday, 30 November 2015 18:55 posted by john

    Great job guys! finally a complete 737 for Xplane... When available for release I will be there to support your efforts...
    WOW! A complete 737 for Xplane will soon be born....That's exciting!

  • Comment Link Monday, 30 November 2015 18:54 posted by john

    Great job guys! finally a complete 737 for Xplane... When available for release I will be there to support your efforts...
    WOW! A complete 737 for Xplane will soon be born....That's exciting!

  • Comment Link Saturday, 14 November 2015 02:23 posted by Alex

    Our very urgent desire; release the beta... its time, don't hesitate.. tic toc..

  • Comment Link Sunday, 08 November 2015 16:42 posted by Chaps

    I think it is time for a "more frequent update" , otherwise your updates will not be more frequent but as per usual. You last was Sept 6 we are now Nov 8. :(

  • Comment Link Wednesday, 04 November 2015 17:15 posted by william muilwijk

    how can i download the boeing 737 i'm a beta tester for something aircrafts
    but i would like to test the b737 as can

  • Comment Link Tuesday, 03 November 2015 11:04 posted by DAI Media

    I will be very happy to at least know some news updates of the current status of the project. I m sure that i m not only one.
    Great works guys.

  • Comment Link Sunday, 01 November 2015 19:56 posted by MauMau

    Waiting for an update...
    great work guys!

  • Comment Link Saturday, 31 October 2015 23:30 posted by roland

    gliding season is over, T minus 1 month untill insanity ;) Hoping for an ixeg christmas.

  • Comment Link Sunday, 11 October 2015 00:37 posted by roland

    You van not,until it is released

  • Comment Link Saturday, 10 October 2015 20:54 posted by William Muilwijk

    How van i download
    THE Boeing 737-300

  • Comment Link Friday, 09 October 2015 12:43 posted by Tony

    It must be time for a frequent update... please say it is

  • Comment Link Tuesday, 06 October 2015 20:53 posted by Alexander

    It is a completely awesome project!
    Love this classic 737 mechanical gauges showing engine parameters.
    Gonna buy it as soon as it will be released :)

    >It is "the last point before the end of route or route discontinuity with an AT altitude restriction".
    >Try to put that into code. Phew.

    Yeah, I totally understand you guys.
    Wish you less or even NO bugs and more good ideas on how to implement remaining features. :)

  • Comment Link Thursday, 01 October 2015 03:32 posted by Alex

    Pls. I dont mind paying for the Beta and get updates later.

  • Comment Link Wednesday, 23 September 2015 21:23 posted by Saul

    I really hope the project hasn't gone! 'Cause in Brazil we've 3 cargo companies flying the 737SF

  • Comment Link Tuesday, 15 September 2015 18:16 posted by Chaps

    Thanks for the promising update. Hopefully, it will be ready for Santa to put under the tee at Christmas time. Really looking forward to this one.

  • Comment Link Monday, 14 September 2015 06:05 posted by Iain

    Let's hope it's not too far away, Air New Zealand just retired their 737 classics.

  • Comment Link Saturday, 12 September 2015 19:44 posted by Jeffrey

    Thank you for the update! Would love to see frequent updates from now on! Looking forward to this beauty!

  • Comment Link Monday, 07 September 2015 21:24 posted by Ryan

    I can't wait to start flying this beauty around! Needless to say but I am very excited!

  • Comment Link Monday, 07 September 2015 09:27 posted by Phil

    Great news..Sounds like the VNAV has been a bitch

  • Comment Link Monday, 07 September 2015 01:33 posted by Paulo Zenari

    This will certainly be the most detailed aircraft for XPlane ever. Thank you for all the work. I'd like to thank better by buying a license though... :)

  • Comment Link Sunday, 06 September 2015 21:54 posted by Tony Curran

    Thanks for the update so looking forward to this bird.

  • Comment Link Sunday, 06 September 2015 20:31 posted by ju

    YEAh ! thanks !

  • Comment Link Sunday, 06 September 2015 16:06 posted by Steve

    It alive! That is fantastic news. Please release now and then do updates for the VNAV and other misc features. Thanks!

  • Comment Link Sunday, 06 September 2015 15:30 posted by Alex

    Great news, thanks for the update Jan. Where's the Buy Now Button... ;)

  • Comment Link Sunday, 06 September 2015 15:19 posted by Joseph

    Thank you for the update Jan :) Keep up the outstanding work that you are doing :)

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