Posts by MDIvey

    thanks for suggestions guys... I have some idea of what to try next.

    Steve.... I'm still a bit perplexed by what that X0 value is meant to be. What I actually did was take points from the actual hinging axis for the upper part of the undercarriage and use that vector calculator I made to get the values.... which does point forward more than other directions. I'm getting the impression from what you said that the vector maybe needs to be along the line the undercarriage takes when it's up?

    I think ill try and get the gear to retract just through 90deg first and then if that works hopefully you guys can help me work out how to deal with that compound angle. It's very tricky geometrically, but I understand why it was done.... because of the wing box spar.

    Let you know how it goes.


    The Graphic parts do seem to be rigid body graphics rather than say bending body graphics. Comparing different TMD files I notice with bending body graphics an additional code section is needed to specify the rotation axis and pivot and where the angle comes from... where as rigid body graphics don't seem to need this... perhaps because you've already specified that in the dynamics section. I wont mess with this until I've got some feedback from you guys so that I don't waste time going in the wrong direction... but I'm obviously looking for the simplest way of doing this.


    Do you have the same pivot point on the lower side of the gear and the upper side of the gear?

    Sylvain ....In answer to your question I'm not sure I have. I took the inertia box size of each object from the information displayed top right in AC3D and the R0 value was the object centre displayed in the object information box. Is that incorrect? Wouldn't be surprised😀


    I think I copied the code from the Baron and so I guess the B0 values was omitted. I read somewhere that it can be omitted if the standard matrix is required. You may have a point here Kai. I may have to work out the angles involved and put them into Jans matrix generator. I guess I'd been thinking that as I'd put the axis vector in the joint it wasn't needed. Certainly worth looking further.

    The parts do return to correct position. I will post whole TMD later when I get time so you can see if the graphic bits are wrong.


    Here is code for left Gear, rigid body section

    What I thought I'd done and what I've actually done could be very different. I think I've made the pivot an angled axis on the join with the fuselage. The lower gear is joined to the upper and has a linear translation axis that follows the centre of the upper leg. The Hydraulic cylinder should be pulling the gear upward via an offset pivot on the upper leg and the oleo should be placed so as to stop the leg collapsing on itself. The gear looks like below. Ignore the hydraulic cylinder visualization as I changed this to a vertical orientation since you don't see it... adding the parts just help me find the R0 and R1 point values


    I have adopted that approach... just been working on the left gear. Figure if I can get that to work I should be able to apply that to the right. Had a bit of time this morning so I tried tinkering with it, but it still doesn't work as I expected. Hey Ho :) I've run out of ideas for now.


    Matt me old mucker, don't give up, your models look fantastic and are much needed.

    Reach out to our Jedi Master Obi Jan Kenobi. The undercarriage is the hardest bit, I don't get it myself but I'm willing to have a look if Master Obi Jan is busy


    I did ask for Jan for help with this a couple of weeks ago Steve and didn't even get a reply. I understand Jan's busy, but I cant waste endless hours without purpose stabbing in the dark. I'm not totally thick and have worked out a lot of stuff for myself with little or no help and I'm pretty certain If I was helped over the hurdle of the UC then I wouldn't need to keep asking the same questions again. However it does seem Jan is the only one who really knows what they're doing and if he isn't available then there doesn't seem much point going on with this.


    FYI I'm suspending work on developing these projects for Aerofly FS2. Disappointing I know and I'm sorry believe me... the models look great and AF2 is a great SIM. I've made much progress with doing the TMD files for the Spitfire to the point where the control surfaces and Props are working but the Undercarriage has proved to be a brick wall I cant get over though I've spent many hour trying. The incomplete nature of SDK documentation and lack of knowledgeable help available makes this a battle I don't think I can win. I may continue working on them with a view putting them in another SIM like XP11, but as far AF2 is concerned its over at least for now.


    I think that would be ok as far as anything I post here but always with Caveat that you use at own risk. Bare in mind though Nick this is for Aircraft specific development... might be better to have a separate thread for Scenery specific development stuff... otherwise could get confusing possibly?



    The Spit has split flaps... a small one on the straight stub of the Wing and a larger one outboard on the main dihedral part of the wing. I managed to get this to work along with that insane 85deg angle without resorting to the complex jointing that was needed on the Corsair. FYI here is the code. It works fine and I cant see any problem with it but Jan can verify.

    KR Matt

    Dynamics Section (doesn't include references to Flaps in airfoils)

    The figure 1.35 above was what seemed to get the desired angle of extention… was 1.0. Arrived at 1.35 by trial and error but would be nice to understand why:)

    Graphics Section

    KR Matt


    As an example here is the Aileron Dynamics Code I've got so far...

    Here is the graphics section so far... left Aileron only as example

    They work but Id like to set the correct throws if its not too involved.

    KR Matt

    Unfortunately AC3D doesn't allow for that and has no onboard Animation either


    I'm working on the Main Gear in the TMD on the Spit... man I thought the control surfaces where bad. Got some questions related to this...

    what are the R0 and R1 values required here in this code for the gear hydraulic cylinder? Could also do with knowing what the 2D matrix refers to in the linear Interpolation section

    I've placed a dummy cylinder in the model to represent the gear actuating cylinder (by eye to the sketches I've got) but I'm thinking something more is going to be required here? If that cylinder stroke is what is going to determine the arc the UC leg swings through, that's going to waste a lot of time in trial and error as I have no details of that.

    Thanks Matt


    OK Here is the promised normalized vector calculator... an EXCEL 2003 created xls spreadsheet. The usual Caveats apply... use is entirely at your own risk. It works ok for me and Jan has looked it over so hopefully it will be a help to others. After I'd filled a full page of my work diary with the calculations needed for just the Left Aileron of my Spitfire I decided something like this would be worth the effort.

    Important Note the XYZ axis in your modelling program may not be the same as in AF2, so you may need to take this into account when you are putting data into the calculator above. That is certainly true in AC3D but the exporter seems to correct for this when exporting the model TGI file. in AF2... X is FORWARD (Direction Nose is pointed), Y is SIDE to SIDE and Z is UP and Down. Its a pain when taking XYZ co-ordinates from my modelling program as I mentally have to transpose them. Changing them in the model program would require a very odd working orientation.

    here is an example of its use.... The prop pitch axis for my Buffalo. I noticed on both the Spitfire and the Buffalo that I was getting a wonky display of the rotating Prop and it turned out it was the incorrect specification of the pitch axis... you got something like this...

    The three blades of the Buffalo are shown here along with the point co-ordinates required to work things out... obtained from the modelling program.

    as an example here is the data for propeller2 put into the calculator… in this instance I only needed the axis and not the pivot

    data added to the TMD code....

    More normally you want the axis and pivot... The Buffalo left Aileron is used here to illustrate.

    Hope above is clear enough and will be of some help to others. I would suggest if anyone adds technical info like this they give it a clear header as above...

    makes it easier when searching.

    KR Matt