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Thread: Project Dornier Do-17z2

  1. #151

    Do17-z2 V8 model

    Hello Smilo, hello Ivan,
    So hereīs an updated Dornier Schnellbomber Model!

    -I was panelling more than just the control surfaces, but I had the feeling it was excessive, so Iīve left it at only the control surfaces. Then I was adjusting vertices (again) and I think it has improved.
    -The T-kaīs on the fins are higher, thicker and more centered as Smilo had suggested.
    -The .air file now has 0.25 in the elevator trim, and it should be easier to trim.
    -The model now has prop blurs, whose animation settings are adjusted as per Ivanīs suggestions from an old thread pointed out a few days ago.
    -Parts count is at 148.5% without any issues.
    -The panel is the last one I made, with axis guages and the .zip also contains the German version of the twin-engine thrust lever guage.

    Improvement suggestions will as always be very welcome indeed!
    Attached Thumbnails Attached Thumbnails V8 screenshot.jpg   V8 screenshot2.jpg  

  2. #152
    SOH Staff
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    3,756 have been busy.
    i will install it shortly.

    my panel progress(?) report;
    spent several hours yesterday
    aligning gauges, but am still not satisfied.

    while looking in my aircraft folder,
    i saw a ju88 panel that looked very good
    and may be acceptable with a few modifications.
    then, i decided to search for a panel package
    i had downloaded long ago...found it,
    but, nothing there that will work for us.
    i also found a couple Panel tutorials
    that may be helpful for those of interest.

    okay, back to the Do17...i decided to follow
    my own advice and downloaded the cfs2 Do17.
    the panel bmp looks very good, but,
    needs to be converted to 256 colors.
    i'm hoping someone knows how to do that.
    of course, it it's decided to use this panel,
    permission must be gotten from the author.

    that's it for now,
    back to the salt mine
    sometimes the magic works.
    sometimes it doesn't.

  3. #153
    SOH Staff
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    State of Confusion..... -8GMT
    well...that was easy.
    all i had to do was open the panel bmp with paint
    and color the two, top left pixels 0,0,0 true black,
    save and done
    this, is a very nice looking panel
    sometimes the magic works.
    sometimes it doesn't.

  4. #154
    Hello Smilo,
    Iīm looking forward to seeing the new panel! We arenīt pressed for time, you know that, so thereīs no hurry.

    I still have to SCASM the virtual cockpit and then see how I can eliminate the engine nacelle bleeds through the floor from the interior view, and thatīs also SCASM.

    At the moment, Iīm also busy investigating the Ad2k tutorials, with the complicated sequencing, so thereīs really no hurry.

    And, letīs hope Ivan can refurbish his development machine conveniently!


  5. #155
    SOH Staff
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    State of Confusion..... -8GMT
    minor update, i found a very cool looking
    Sperry MIII auto pilot. problem is,
    i haven't figured out how it works.

    oh snap!!!
    i just clicked on some text on the gauge,
    lo and behold, a help document popped up.
    apparently, it was built to hold heading and attitude,
    not to turn automatically to the desired heading.

    stay tuned...i'll see if we can use this gauge.
    sometimes the magic works.
    sometimes it doesn't.

  6. #156
    Hello Smilo, Aleatorylamp,

    Thanks for the check for general Panel Tutorials.
    As usual, I am going in too many directions. Am working on Texturing, Gauge, and Propeller issues......
    It seems like each has hit a dead end except for texturing and that is just tedious to do.

    Isn't it always the case that we are good at finding things that we don't really need and not able to find the things we need?

    - Ivan.

  7. #157
    SOH Staff
    Join Date
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    State of Confusion..... -8GMT
    that, sir, is the story of my life.
    i could go into a long winded dissertation
    on the trials and tribulations
    of the never ending search,
    but, i don't want to bore you.

    another day has evaporated
    while i've been siting in this chair.
    yes, i did get up a few times,
    but, the minutes turned to hours
    long before i realized they had passed.
    time flies when your having fun.

    here's a little sampler
    of what i've been up to;
    Attached Thumbnails Attached Thumbnails Do17_Panel.jpg  
    sometimes the magic works.
    sometimes it doesn't.

  8. #158
    That looks very enticing indeed, Smilo!

  9. #159
    SOH Staff
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    there are some issues...
    since all but five of the gauges are stock,
    they are all for single engine aircraft.
    basically, making half of them just eye candy.
    i never got into gauge programing,
    so, consequently, am unable to make
    a new set of functioning #2 gauges.
    i may have multi engine gauges somewhere,
    but, am not sure you want to include
    a big extra gauges folder with the model.
    i'm also pretty sure i don't have a big selection of german gauges.

    i'll start working on the pop up windows shortly.
    auto pilot, radios, bomb aimer, and so on.
    is there anything specific you want to see?

    one more issue...
    there seems to be something
    amiss with the auto pilot.
    when ap altitude is engaged,
    instead of remaining stable,
    the aircraft altitude fluctuates.
    sorry, at this point, i can't give more information.
    i'm sure it's some setting in the air file,
    because the auto pilot works fine on other aircraft.
    i'd try to fix it myself,
    but, i'm not an air file tweaking kinda guy.
    sometimes the magic works.
    sometimes it doesn't.

  10. #160
    Hello Smilo,
    ...Thatīs why I use mostly default FSFS engine-gauges for multi-engined aircraft (RPM, CHT, oil and water temp, etc.), even if they do look a bit modern.

    The fluctuating in the autopilot, on one side, has to do with the elevator trim parameter in the .air file, and itīs more difficult to get it right in CFS than in FS98.
    At the moment itīs at 0.25, and it was at 0.5 before. I donīt really know what valueīs best.

    Maybe it is also affected by having the tailplane incidence at non-zero.
    Perhaps Ivan can explain better how to counteract this porpoising in the AP.


  11. #161
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    the Do17 porpoising is slow and undulating,
    but, still not acceptable for a good bomb run.
    i could be mistaken, but, i think v7 had it, too.
    i'll go back and double check earlier versions.
    this is nothing, compared to the stock fw190.
    that thing porpoises wildly and picks up speed.
    in multi player, i would always get caught by a p51.
    but, if i switched the ap on soon enough,
    i could out run one very easily.
    yes, it was kinda cheating,
    but i didn't modify anything.

    as i recall, many years ago,
    Ivan did some air file work in that department.
    danged if i know what he did, though.
    patience, milo, patience.

    as for the gauges, yes, i could do another panel,
    with stock multi engine gauges.
    true, they're not historically accurate,
    but, they're more usable for us non german speakers.

    are we limited to cessna gauges
    or, are there other multi engines in fs98?
    i guess it doesn't matter...
    there are only cessna in the cfs gauge folder.
    i was trying to keep it stock.
    sometimes the magic works.
    sometimes it doesn't.

  12. #162
    Hello Smilo,
    Yes, in versions before, the porpoising was worse. I was trying to adjust AP for flight testing at different altitudes, and it only worked on some planes.

    Looking further into CFS1, given the options in the menus, I donīt really think APīs were meant to be used on this simulator, as combat flying would be done manually, but as it had to be compatible with FS98, they had to let an AP work. How, is another matter!

    Then, basically, FSFS gauges for piston engines are all only Cessna ones, Iīm afraid.


  13. #163
    SOH Staff
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    State of Confusion..... -8GMT
    3,756 the early days, i often asked,
    what's up with this auto pilot feature?
    as you know, there are several options
    in the controller settings section.
    i never really used it until i got into the heavies,
    were straight and level flight, along with
    making minute course adjustments
    were essential for making a precision bomb run.
    ap is also valuable on those long waypoint missions,
    especially in multi player, were you don't press x
    to jump to the next waypoint.

    i'll never forget a joint ops graduation mission.
    i had to plan and execute a bomber escort mission.
    i was flying top cover over france,
    escorting the bomber at high altitude.
    we were both using auto pilot.
    at one point, i inadvertently, clicked off my auto pilot
    and lost control of my p51. i was plunging earthward
    and couldn't pull the bomber, my instructor
    kept saying, don't crash, don't crash.
    fortunately, i was able to pull out near the deck.
    much later, i came to understand, the ap altitude
    was governed by elevator trim. when i kicked it off
    at high altitude, the aircraft was still set at high elevator trim,
    forcing me to loose control.
    at least, i think that's what happened. and learn.
    sometimes the magic works.
    sometimes it doesn't.

  14. #164

    Auto Pilot Stuff

    Hello Smilo, Aleatorylamp,

    It is still rather difficult for me to get time on the game machine to do any testing.
    My development machine also has CFS installed but as you already know, it isn't cooperating.
    My time is still not my own for a while longer. There are times when I have my laptop and have nothing else to do but that does not work for testing anything unfortunately.

    Regarding the Dornier 17Z and Autopilot, I need to know a few things:

    1. What is the Zero Fuel Weight (Weight in the AIR file that you are using)?
    My intention is first to sanity check the Moment of Inertia values to see if they are appropriate.
    I suspect that they are not. AI Air files tend to be screwed up in one way or another from what I have seen in the past.
    I can do the MOI calculations as long as I have a laptop and access to the web to pull some dimensional specifications.

    2. I had a chance to download V7 over the weekend and flew it for a few minutes.
    I believe it is way too agile in Roll and especially in Pitch.
    The sensitivity in Pitch is why I suspect that the MOI is too low but it is possible though less likely that the damping is too low.

    3. Once those are "correct", then the easiest path is to adjust the trim effect per notch.
    What to do depends on what the aeroplane is doing under autopilot.
    If the oscillations are divergent (Get larger and larger) then the chances are that the trim effect per notch is too low.
    That is because the autopilot can only change trim at a certain number of notches per second.
    If the effect per notch is too small, then the autopilot cannot follow the changing situation and thus the pitch diverges.

    If the autopilot cannot hold altitude (constantly goes slightly up or slightly down) then the probable reason is that the effect per notch is too high. It may be looking for a value in between where it can actually go.
    If you turn the simulation speed up, you might see the aeroplane look like it is "shivering" because the notch changes happen quickly and have too great an effect.

    It is also possible that you cannot find a notch value that solves both problems.
    If not, then go for one that is slightly too small. If corrections are too great, the pitch will diverge, but that can be "solved" by turning the autopilot off and back on quickly where you expect the trim to stabilize. Keep doing it and the aeroplane will hit a point where the adjustments are not so great that the autopilot cannot correct in time with trim notches that are too small.

    4. If it still seems that nothing fits together, think about minimizing the changes in trim from low speed to high speed.
    I noticed that the V7 seemed not to be very well adjusted for neutral pitch trim.
    That in itself is not a problem because many real aeroplanes are not well adjusted there.
    Consider that this is what happened in real life with Jimmy Leeward's racing P-51 (Galloping Ghost) crash in 2011.
    His aeroplane was running at around 530 MPH with full nose down trim to keep it going level.
    When the trim tab fell off, all of a sudden, he hit somewhere between 11G and 17G.
    It collapsed his seat and probably rendered him unconscious immediately.

    With CFS, we actually can adjust the flight model for minimal trim changes with speed and the trim changes become much easier for the autopilot to deal with.
    One can also adjust the AIR file so that it flies with neutral trim (pitch only) at a particular speed and altitude (and fuel load).

    Yet another solution is to determine the trim settings required for a particular flight condition such as during the bomb run and list them in the checklist.
    I do this for the projects I build.
    It is tedious to do, but it is useful information for the virtual pilot.

    Hope this helps. If not, I will see what I can do about the AIR file in a couple days.

    - Ivan.

  15. #165
    Hello Smilo,

    I almost forgot to address the situation you brought up.
    First of all, the deal with trim on the FW 190A as you probably already know is an interaction of a few factors that are just plain wrong.
    The flight model is garbage anyway. I actually created a very similar situation with my A6M2 flight model with the intentional oscillation.
    I wasn't trying to create such a situation but all of a sudden, I had the Zero under autopilot going about 40 MPH faster than it would normally.
    I didn't explore any further but I do know it happened.

    Your situation with the P-51D should not happen in real life, but does in the simulator (I believe) because trim notches are too large.
    It makes the aeroplane unable to hold altitude exactly, because the trim setting is never stable.
    Instead the autopilot is constantly switching it back and forth by a couple notches.
    The problem is that when your autopilot goes off, YOU as a human cannot react fast enough to correct for a setting that may be very far from where it should be for equilibrium. This is what I believe happened.

    In real life, most fighters did not have any autopilot which meant that the pilot had to manually trim the aeroplane for straight and level flight.
    .....So there really was no autopilot to be lost.

    BTW, your Dornier 17Z panel looks great.
    Your issue with the twin engine gauges is exactly why I am working on gauges myself.
    I am also working on plans to set up an experiment to help in figuring out how to do things but won't be able to do that either for a few days.

    - Ivan.

  16. #166

    weight in .air file

    Hello Ivan
    Thanks for your detailed info and instructions on autopilots. Iīll see if I can remedy the flaw.
    Everything you say should come in useful!

    Re. your question on the weight for the Do-17z2:

    Empty weight:..................11486 lb
    Crew of 4:...........................800 lb
    Guns: 6x115 lb ....................860 lb
    Dry weight in .air file:.........13146 lb

    Standard Fuel:409 USG........2454 lb (no extra fuel tanks)
    Bombs:.............................2205 lb (20 x 110 lb, although for long range half the number were carried)
    Ammo: 4x1000 rounds...........113 lb (there are only 4 guns defined in the Dp files. 6 would be 169 lb).
    Operational normal weight: 17918 lb

    Thanks a lot for your time and help - I know you are quite busy with other stuff these days...

  17. #167

    Pitch and Roll moments better

    Hello again, Ivan and Smilo,
    Pitch and roll sensitivities are more correct now:
    I had the elevator pitch moment at -1800 and aileron roll moment at -180,
    and tuned them down to -1200 and -120.

    Now itīs somewhat better:

    If oscillations are more or less "normal" at around 100 fpm they get weaker and disappear.
    If they are stronger, they wonīt, but I suppose itīs normal.
    Changing elevator trim from -0.25 to 0.20 didnīt help, as the more normal oscillations wouldnīt stop.

    This seems to be coherent with your comments.
    Then, I tried increasing the pitch MOI but it makes it worse, so I left those.
    I could try further reducing pitch sensitivity, but maybe the plane will loose too much manouverability.



  18. #168
    Hello Aleatorylamp,

    Just a couple comments....
    I don't believe the Dornier 17Z really was all that maneuverable.
    It was a fairly underpowered bomber though its aerodynamics apparently were not too bad.
    I had noticed that it seemed to be a bit overly sensitive in pitch or at least such was my impression.
    The roll rate also appeared to be way too good; There were no issues in doing a complete aileron roll.
    I did not time it, but you might want to do that to get an idea of how it compares to a typical fighter.

    I can't recall if I mentioned changing the pitch damping.... I don't think it will cure your autopilot problem but it will address some of the pitch sensitivity.

    I am fairly certain that your ammunition load for the MGs is way off for weight.
    The value I would use here is 1.12 ounces per round.
    This is for a disintegrating link belt and that is not necessarily what was used for this aeroplane, so the number might be a touch off.
    Now keep in mind that the actual guns used in the Dornier 17s were loaded with a 75 round saddle drum and we are not taking into account the weight of the magazines.... But the magazines are not thrown out the window when empty either.......
    If in doubt, just look up what a single complete cartridge of 7.92 x 57 weighs with about a 175 grain bullet.
    I don't remember the actual bullet weight for their aerial guns, but I am betting it is pretty close to that.
    Don't use SAAMI numbers because that is only for US commercially loaded ammunition.
    I probably have a few rounds of this caliber in the basement but that is likely to be with either 153 grain bullet (Chinese) or 196 grain heavy ball (Portuguese) and with things all over the place, I don't even know where to look at the moment.

    Your weight summary seems to be working on the assumption that the loaded weight (is it just a normal loaded or maximum take-off weight?) is with full fuel AND full bomb load.
    Do you know this to be the case? Usually it is not.

    I haven't been able to find a copy of the spreadsheet I use to calculate MOIs but that isn't a hard process.
    It is documented pretty well by various sources and is pretty much an estimate anyway with as little information as I could actually find on the aeroplane.

    Hope this helps.

    - Ivan.

  19. #169
    Hello Ivan,
    Thank you for your input, help and suggestions! Iīll see what I can do to make pitch and roll more realistic.

    Then, Iīll check the ammo weights. Iīd looked them up in oz. and put in 1000 rounds per machine-gun, with 4 being in the Dp files, but 6 in the .air file weight. MTOW is 19482 lb, but normal operational weight wasnīt Maximum take-off weight. Adding up standards fuel, crew, ammo and bombload, I got to 17918 lb. I donīt really want to fly a fully laden plane with the extra long-range fuel - Iīd have had to reduce bomb load anyway. I thought it would fly better being 1500 lb lighter.
    Anyway, Iīll check the weights again.


  20. #170

    Aircraft Weights

    Hello Aleatorylamp,

    Tonight I went back to where I was storing various aircraft information and found a data sheet I had written back in 2010.

    Regarding Weights:
    Empty weight according to my notes is 11,484 pounds.
    The book "Fiegende Bleistift" by Manfred Griehl gives 5200 Kg which is 11,464 pounds.
    Both numbers are in pretty good agreement with your value of 11,486 pounds.

    Where I believe you are missing data is your lack of a listing for "Empty Equipped" weight.
    US Aircraft often call this a "Basic Weight".
    The empty weight only includes basic airframe, engines, fuel tanks and very little else.
    Armour, radios, gun mounts, gun sights, guns, emergency equipment such as a raft, flares / flare guns, charts, etc. are not typically included.
    The value I have listed for Empty Equipped is 13,145 pounds.
    To me, even this seems a bit on the light side.
    By the way, the MG15 was a relatively lightweight machine gun. I believe they were only about 20 pounds or so each.
    Even the .50 Cal Browning was only about a 75-80 pound gun.

    To this we add the 4 man crew.
    Germans must be a bit heavier than others because the typical German aircraft documentation allows for 100 KG per crew member.
    That would add (for simplicity's sake and to allow for personal belongings) about another 1000 pounds.

    We are in agreement for fuel. The wing tanks could take 1550 liters or 409.52 US Gallons which would be 2457 pounds.
    2454 pounds is good for 409 US Gallons.
    This presumes that the ferry tank in the forward bomb bay is not installed.

    Bomb load is 1000 Kg as specified so 2205 pounds is good.

    I have the armament listed as 5 x 7,92 mm MG15 and a MG151/20 20 mm cannon as the swivel nose gun.
    It sounds like the nose gun could vary which would explain why the nose framing was not always the same where the gun was mounted.
    Assuming 6 x MG15 machine guns, we would have 6000 rounds of ammunition
    Even though your DP only has 4 guns, it makes sense to include the full 6000 rounds.
    The ammunition came in 75 round saddle drums carried on racks so it wasn't necessarily dedicated to a particular gun anyway.
    At 1.12 ounces, that would give 420 pounds for 6000 rounds.

    So what I am getting is
    14,145 pounds Zero Fuel Weight
    420 pounds Ammunition
    2205 pounds Bombs
    2457 pounds Fuel

    for a total of
    19,227 pounds for full fuel (no ferry) and bombs.

    The number I have for an "overload" weight is 19,481 pounds which agrees with your value of 19,482 pounds.
    Manfred Griehl's book lists the Fluggewicht as 8860 Kg which is 19,533 pounds which is only a bit above our maximum weights.

    So with the exception of equipment weight, we are in pretty fair agreement.

    - Ivan.

  21. #171
    Hello Ivan,
    OK!, it seems I was doing my arithmetic starting out with wrong numbers then.

    So, just to understand it: First, Iīll use the 13145 lb empty equipped weight to include the guns, radios etc, increased by 1000 lb to include crew and their stuff (800+200 x 4), giving 14145 lb, and after that, add 420 lb ammo, and the normal fuel and bomb weights.

    Then, the 6000 ammo rounds in the Dp file would be 4 guns with 1500 1.12 oz rounds per gun, one of the forward ones being a cannon. Shouldnīt all 4 swivel?

    That, with increased MOIīs and lower pitch and roll sensitivities should then do the trick.

    I already had the sensitivities lowered, and
    Iīve just done the rest. Now, aircraft movement around the three axes is more fitting with the added weight and lower MOIīs. Funnily enough, the unwanted the peaks in the performance curve are now smaller! So thatīs great too!

    Now, the only pending thing is the Autopilot oscillation, although, for the moment, it CAN be controlled with able damping joystick movements to reduce it to within + - 100 fpm, and then it will settle to near zero after a short while.

    Attached, please find the new .air and Dp files.

    Thanks a lot for your indefatigable help!
    Attached Files Attached Files

  22. #172
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    got em, thanks.
    will move them to sim machine
    and go a flyin' later this morning.
    sometimes the magic works.
    sometimes it doesn't.

  23. #173
    Hello Smilo,
    Glad itīs working!

  24. #174
    SOH Staff
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    State of Confusion..... -8GMT
    i haven't done it yet.
    as always, i'm behind schedule.
    sometimes the magic works.
    sometimes it doesn't.

  25. #175
    Hello Aleatorylamp, Smilo,

    Here is a little more of an explanation for the Empty Equipped and additional 1000 pounds for the Air Crew.
    In reality, the Germans specified each crew member and equipment as 100 Kg.
    I joke about Germans being heavier than others, but that is the number they chose to use.
    Americans typically used 200 pounds per crew member but not always.
    Japanese typically used 75 Kg per crew member.

    (For the very special P-39 Airacobra, I have actually seen a reference where the weight of the pilot was specified as 150 pounds and that was an American plane.)

    So, if I know the crew of the Dornier 17 is 400 Kg or 880 pounds, why did I use 1000 pounds???

    My belief is that the Empty Equipped weight does not account for trapped fluids such as Engine Oil, trapped Fuel, etc.
    A few gallons of oil easily make up the difference. There are also other little personal items which would suggest that 120 pounds is probably a low estimate. Perhaps some of the personal items are included in the crew weight?
    It is hard to know for sure.

    To get an idea of typical numbers, check out this thread on the FW 190A for which I had a very good listing of equipment weights.

    I SHOULD finish up that project and re release it. It is one of my favourites.

    - Ivan.

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