JaBoG32_Dirty

Hi I've been playing around with DCS' export interface and I would need the aircrafts angular acceleration for a project. Does anyone know if this is available for export directly? Of course, I can use angular rate ( LoGetAngularVelocity() ) and calculate ∆value/∆time, but that would give me a one frame delay that I would like to avoid if possible. Cheers,...

Excelent question to ask before buying I've been using Realsimulators FSSB sticksbases in various versions for the past 18 years as my only stick and for anything FBW there's really nothing that even comes close. Reason is, in FBW aircraft you use the stick for a single input parameter: Stick deflection (Airbus/Boeing) or sick force (F16 etc.). The flight control laws in the FCCs will then decide wether this input leads to AoA or G-load or pitch rate depending on flight phase, configuration.... Also, in FBW aircraft controll inputs are one-way, meaning you do not get any feedback from the aircraft through the stick. For converntionally controlled aircraft (cables, pushrods and alike) stick deflection and stick force are not directly correlated and can be used somewhat seperately: In pitch for example, stick deflection will be proportional to an alpha-demand, while stick force will be proportional to a G-load demand. At least over a wide range of the flight envelope. That's why conventional sticks are better suited for conventional aircraft, even though few people use a proper controll loading system at home. It still gives you that element of deflection in your controll setup. Helos are even more leaning towards being controlled with deflections rather than force, so I would definitely try out that stick before deciding to keep it. In Europe, you generally have a 14 days return policy on online purchases. If you're unpacking it carefully, you will be able to just get it refunded if you don't like it. And above all: This is an awesome stick!! You will never be flying with deadzones again, that's for sure. Cheers,....

That sounds interesting. 30% is a huge error indeed. Even for a 1970s aircraft. What you could do is check the data in the export interface and see if that matches up. Maybe I will do that when I find the time.

There is another thought that crossed my mind: Does anyone know how the value of trim is represented internally in DCS code? I mean, if it is stored as a single byte value (only 256 states), it would explain why it behaves so granularly. Again: I found the numbers to be very plausible, I just think it should be adapted for easier use given the restrictions of simulator flight. Dirty :-)

I have been observing similar behavior on trim as Sylosis, and am kinda glad I am not the only one noticing it. The funny thing is, that a few years back I looked into the trim rate of the real T38 (knowing it is a similar airframe as the F5) and found the trim rate in DCS' F5 to be very close to the real thing. Still, I would suggest slowing it down or adding an acceleration ramp to the trim rate, to make it more useable in the sim. After all, most of us are flying without any tactile feedback and it could help precision tremendously. I even used an Arduino to generate the smallest possible trim increment (1 frame) and I noticed, that in an F5 at typical cruise airspeeds, this "quantum" of an input was already enough to change vertical G by about 0.01G. That is quite a big change. For example: Typical autopilot inputs in airliners use changes in vertical acceleration of around 0.15G at max for flight level changes. Cheers,... Dirty :-)

Hey, just watching the video you posted :-) (Messerschmidt) "The Book" is also what I learned from back in the late 90's. Back then I already thought it was a century old, but he's right: "The Book" is THE book to read when it comes to aircraft performance! Great video!

Thanks, nice to hear that :-) It was fun exploring the data and I guess I will do a couple more. Concerning the video, I clearly seem to be too dumb for that... If I write [YOU_TUBE] [/YOU_TUBE] (without the _ of course) I get this: ${1} Anyways, thanks for watching :-)

Hey :-) I took a closer look into the power-on and power-off characteristics of the L39C. I know this in not going to be the Blockbuster of the Year video on YouTube, but maybe there are a few die-hard flight-performance-data-nerds (like I am) around here who appreciate :-) A bunch of more videos still cooking in my mind. Maybe cruise performance, turn performance or fuel consumption could be of interest for serious pilots flying in squads. Not sure,... let me know. Power-on perfornance: Power-off performance: Enjoy... Dirty p.s. If someone could explain to me how to properly embed YouTube content in here, I'd appreciate :-) EDIT: Finally got it :-) Thanks a lot, @Ramsay

Exactly! :-) Adverse = Against the direction of the control input (as opposed to proverse). Yaw = Rotation around the vertical axis (for DCS this is the y-axis) Btw, I actually work in the field, and I wouldn’t know what better term to use to describe this behaviour. But whether you like this expression or not really isn't the topic. What is, is the fact that in this scenario the simulated vehicles in DCS experience an angular acceleration around the vertical axis that is in a direction that is opposite to the control input. I did my best to bring this to the developers attention and have unfortunately not gotten an answer from anyone who actually worked with vehicle motion dynamics in a professional way. I found this behaviour on other models, so I guess it is not type-specific. Furthermore, I found taildraggers topple over forward (not sideways!) easily with high sideslip angles as well. That observation too supports my thesis: The reason for the strange behaviour at high wheel sideslip angles is that DCS calculates a drag-term that is opposite to the vehicle direction of motion, when it should instead be opposite to the relative direction of the sliding surfaces. For a free spinning wheel that direction is always along the wheel axis. And again: Yes, you can still enjoy DCS World. I do too! Not a big thing! It’s just that I would’ve expected to at least hear from a developer briefly.

...Oh, and something similar: I saw somewhere... MainPanel = GetDevice(0) local ias = MainPanel:get_argument_value(49) ...again, where would I find a list of what data this function returns for the posssible arguments? Any help would be greatly appreciated!

Hey there, I would like to export some data out of DCS for a project. Somewhere in a post I stubled across "LoGetAircraftDrawArgumentValue(n)". Now, I'd love to use this function to read data, but I only know what the function returns for very few arguments. e.g. local NoseGearStrutCompression = LoGetAircraftDrawArgumentValue(1) local RightMainGearStrutCompressionr = LoGetAircraftDrawArgumentValue(4) local LeftMainGearStrutCompression = LoGetAircraftDrawArgumentValue(6) ...can someone point me off in the right direction where I might find out what the returned data for more (all) possible arguments of that function is? That would be a tremendous help!

Hey there :-) Can anyone tell me where exactly the exported accelerations that LoGetAccelerationUnits() returns are picked up from? I would assume that it is vehicle center of gravity, but it might also be pilot eye reference position or any other reference position on the aircraft. Does anyone know this for sure? I am building a hexapod motion system, and it could make a small but noticeable difference. Not in flight, but certainly during taxi. I will have to correct for this anyways, but it would narrow down my trial and error process a lot. Dirty

Hey guys :-) I'm observing the same system behaviour as Moafuleum. And am also wondering where this is coming from. Basically I understood the question to be "Is this a bug or a feature?" I am aware that it would make sense to use two different phrases to make the left and right fire warnings easier to distinguish. But still: Is that part of the design, or unintentional? I am aware that it does not show if the start-up procedures are followed correctly. But still: Why does it have two different sound files? And yes,... I'm aware that it doesn't make a difference for the casual gamer who just wants to fire up the Hornet and blow some bad guys out of the sky every now and then. Nothing wrong with that :-) ...but if someone (devs? ...anyone?) has a plausible explanation for this behaviour, I'd appreciate! Dirty :-D

Yes, yes,... I said it before, I say it again: This is NOT pressing, major-issue, important, urgent, deal-breaker, necessary,... etc. This is simply an attempt to find like-minded people to discuss with and exchange ideas about something we are all somewhat interested in and passionate about. In mutual respect and with full knowledge and acceptance of the others thoughts and ideas being their own and not a copy of mine. If someone finds other aspects of the sim worthy of discussion, they may start a thread and I'd be willing to add my point of view to it, if I have anything substantial to say about the topic of discussion. But at no point will you ever see me questioning the very existence of the discussion itself. If I ever did that, I'd have to question my own participation in it first! Dirty

Hey Weta43, I'd like to comment on your post, if I may :-) Please take this in a friendly way. Open-minded and respectful. After all, we wouldn't be here if we weren't infected with the same borderline insane obsession with simulated flying. I really don't care WHO's right, but I do care very much WHAT's right :-) Cars also have caster wheels. It is what lets you feel the lateral forces in your steering wheel when cornering. Even modern power-drive steering provides such feedback. It is essential for controlability in any car. It is not static. It does still spin. It spins at cos(NWS_angle)*groundspeed. It even does so in DCS. Exactly how it should be. If it weren't spinnig you'd be right, but it is :-) Correct! ....for a vehicle in an OVERsteering situation :-) A situation where the angular rate is higher than the wheel deflection demands. A situation where PROverse yaw is being induced from differing friction coefficients between the front and rear tyres. This situation is indeed unstable (at least in fwd motion) but that is not the case here. It is not OVERsteering, it is not even UNDERsteering,... it is ADVERSELY steering :-) ...hmmmm... *blushing_slightly* ...let me PM you :-) I guess many of you understand, that the caster wheel will offset to the adverse side when deflected. What I'm trying to convince you guys to do, is take the "next step" and ask yourselves: where does the resulting force point? Dirty :-D

This IS stuff that matters! :-) ..yea yea,... I know... I agree, that there are more pressing issues on the table for the developers right now. It's not like I can no longer enjoy the beauty of this module. But isn't this forum also a little bit about education, technical understanding and a fair appreciation of the insane amount of detail a modern PC-based flightsim can provide? To me, that is what flightsimming is all about. I want to understand this behaviour at least as much as I want the developers to fix it (IF it needs fixing). Weta43 picked up the point that I made in my second post and what I already said in the video: The nosewheel has a caster. That shifts the contact surface of the wheels over to the side opposite of where you are steering. The point where wheel drag applies shifts with it. So far,... everything appears make sense :-) But that is only the first step of the argument! The second is this: The point where the drag ACTS on the airframe shifts over adversely (due to caster), but the direction where it POINTS is still way over to the provers side. Or to be more precise: The vector of that force still passes the centre of gravity on the provers side --> huge provers yaw moment. All these arguments are founded on the premise, that friction is a force opposite to the direction of the relative motion of the SURFACES involved. Keep in mind: The relative motion of the surfaces is a superposition of the vehicle motion and the motion due to the freely spinnig wheel. That wheel still spins at cos(NWS_angle°)*Groundspeed. The behaviour that can be observed however could be nicely explained if friction was (wrongfully) modelled as a force acting opposite to the direction of motion of the VEHICLE alone. I don't think this is a coincidence. I think it points directly to where the devs should look for a fix :-) I tried my best to explain this in simple words and as math-free as possible. I know, that this topic will not raise huge attention with 99% of the forum members, but maybe there is someone among the other 1% who can confirm or correct my hypothesis. I'd be thrilled either way! As long as I go to bed tonight a little smarter then I woke up,... it was a day worth living :-) Dirty :-D

Hey :-) I'd also be very interested to hear... 1 ...if this is noticed by the devs or how they view it. 2. ...how true vs. mag north should play a role here. aside from devs or moderators, does anyone else have an idea how true/mag could cause this behavior? I'm the type of guy who considers DCS a sim not a game, that's why I find it important. Dirty :-)

Hey there :-) @Weta43: Thank you for being rational, precise and right to the point here. Shows a good (and much appreciated!) amount of professionalism when you said: "Yes, but what IT is, is the question" Thumbs up! I’d like to add a point to the discussion that I don’t see considered in this thread so far: Ground effect is NOT a „cushion of air“! That term is just an image/metapher given to novice pilots to describe what it feels like when entering ground effect. Ground effect IS the reduction of induced drag / increase of lift coefficient close to the ground. Nothing more. I find this distinction to be especially important in this case, because many of you observed this effect when flying close to the ground (or the carrier deck) at rather high speeds. Speeds at which induced drag is an almost negligible factor anyways. Just so that we are all talking about the same thing here: -Wing generates pressure difference —> Lift -Air wants to equalize pressure and thus forms vortices around the wingtips -Vortices are already forming ahead (upstream) of the wing (subsonic flow) -Wing continuously flies in its own downwash —> Kinda like having to fly „uphill“ all the time …when the aircraft is slow, these vortices have plenty of time to form ahead of the wing. …when the aircraft is fast, these vortices have no time to form ahead of the wing and thus the wing will „feel“ the air coming at it at almost the same angle as the free air stream. …when the aircraft is flying supersonic (M>1.5), there should be no more ground effect noticeable. The wing wouldn’t even „know“ that there is a ground present. When the aircraft flies close to the ground, the ground presents an obstruction to the downwash of the wing - greatly reducing induced drag. At landing (slow/dirty/high alpha) that effect is easily noticeable and definitely present in DCS. At high speeds (fast/clean/low alpha) this effect is quasi negligible. In real life as in DCS. While I DO notice this effect and highly encourage the developers to look into this,… I wouldn’t necessarily attribute it to ground effect, because I was only able to reproduce it in fast, clean, low alpha configurations. My guess would be that this effect is neither a feature, nor a bug! I suspect that it is an artefact from some „quick and dirty“ fix they may have applied (I’m speculating here!) to correct something else a while ago. If I were on the team, I’d try to remember (or ask my co-workers) the last time I heard someone say: “We don’t need to fully model this…. Let’s just create this plausible illusion by…“ :-) A broader „crowd-sourced-approach“ to this problem would be to check where else we can or cannot observe this effect: - Is it present in other jets? - Is it present in other props? - Is it present in helos? - Is it present in the AI flight model? - Is it present in other maps? - Is it present during night? - Is it present over water/grass/treetops/buildings/in tunnels? - Is it present when flying close over other aircraft? - Is it present with collisions on/off? - Is it present when flying inverted under a bridge? - Is it present in knife edge flight along the side of a tall building? - Is it present in arcade mode? - Hell,… we could even check if this effect could be reproduced in LOMAC or Flanker 2.0 if someone still has these installed. What I’m trying to say here: Let’s not only focus on ground effect, but let’s gather some data and maybe we can point the developers in the right direction. Doesn’t Wags occasionally mention how often he gets requests from people to be invited into the testers team? Well, THIS is a chance for us as community to be productive and learn something in the process. Wether on the team or not. Have fun!!! Dirty

I too think that the effect from differential braking is too little. In fact, I think that braking in general is very week in the Hornet. Might be plausible, because it's a carrier-based design, but feels VERY weak. NSW HI or not,... I'd expect to see a significant moment with differential braking. EDIT: I have actually tried this out in a plane with hydraulic NWS (please don't tell my employer!) and I think I should correct myself: As long as there is hydraulic pressure on the system the NWS will keep the aircraft surprisingly straight. At normal taxi speeds I was barely able to generate rates over 1°/sek. Wasn't able to test it with NWS off or w/o hyd pressure though. I guess the reason why people (including myself!) expect to see high turn rates with differential braking is because either... 1. ...they use it in planes w/o hydraulically controlled NWS 2. ...they use it to support NWS on wet surfaces when the nose wheel tends to skid easily. That's when differential braking can actually make a difference. Would love to hear what an actual Hornet pilot would say about this... Dirty :-)

I had the same thing. Could it be that you turned off the oxygen flow to the pilots facemask and he died from hypoxia?

Hey :-) I should probably have added: 1. I did not use differential braking. In fact, I did not use any braking at all. Should be visible in the track (CRTL+ENTER). 2. No wind present 3. I tried this on different runways/taxiways/aprons to make sure that a sloping ground does not play a role here. If you want to use the analogy of a car, I'd find that very resonable! If we leave out the fact that this vehicle has wings attached to its fuselage for a monent, we could consider it practically an unpowered car with a high center of gravity that seems to suffer from severe(!!!) understeering. And to all those who want to swipe this under the out-of-scope-carpet :-))))) : Imagine you taxi your Hornet onto the active runway just a tad bit faster than what you learned in flightschool. When you realise that you have quite a big turn radius even with full NSW deflection, you might be tempted to tighten the turn by switching NWS to HI momentarily, giving you access to those extra ~50° of NWS angle. You CAN get away with this at a groundspeed of 11Kts or less, but as soon as you try this at a speed of 12Kts, you will see adverse yaw. It is not THAT far fetched! :-) BTW, I am NOT advocating to reduce NWS angle or even deflection rates. The angle and rates are realistic/plausible. I guess even the fact that there is no logic-circuit to prevent the pilot from doing this is realistic. What I would hope for the devs to do: - Take a look into the friction model, especially into what determines the direction of the force generated by it. - If I'm wrong just let me know that someone worth his salary took a look at it, reproduced the behaviour and decided that the model behaves as desired. - The icing on the cake for me would be, if you could drop me a line here where the adverse moment comes from, cause I have absolutely no clue. Oh,... and because I have not mentioned it: I think the Hornet is a great model!!! And the developers are doing a great job with it! After more than a decade of "abstinence", I'm back in flightsimming because of IT :-) Dirty

Yes, that's correct! :-) If this was a professional simulation product these high sideslip angles would probably be discarded as "out of scope" and that would be the end of it. And to a certain degree I could accept ED to simply consider it out-of-scope as well. No big deal. After all it is a flight-sim, not a drift-sim. However, we expect a correct system response from an incorrectly handled system in many other cases. Like the alignment sequence of the INS or the correct warnings being triggered from shutting down an engine in flight, don't we? Has anyone ever tried to switch off your pilots oxygen flow on the left aft side console? The reason why I pointed this out to the devs is because it might be an indication of an underlying more fundamental error in the modelling of dynamic surface friction in DCS as a whole, not just the Hornet. My hypothesis: This adverse yaw comes from the drag of the wheels being modelled as acting opposite to the direction of TRAVEL of the vehicle. Instead it should act in a direction opposite to the direction of the RELATIVE MOTION of the surfaces against each other. That is not a big factor at low angles, but it is at 75° NWS angle. Long story short: A freely spinning wheel (very similar to a polarisation filter) transmits only force-components along its axis and "ignores" (almost) all force-components within the plane of rotation. That applies even to a wheel at a sideslip angle of 75°. The good news: An incorrectly modelled surface friction COULD explain this behaviour and IF(!) that is the cause, it could be corrected with 3 lines of code. Again, this is not something I'd call "urgently pressing" for us gamers/simers, but if I were a company planning on using a vehicle dynamics simulation engine commercially, I'd love to know where this behaviour comes from to be sure as to wether it is a bug, an artefact or a feature :-) Anyways,... can someone make sense of this adverse yaw? Is there a logical explanation for it? Dirty :-)

Hey there :-) I came across some strange behaviour in the Hornet when the nose wheel has a large sideslip angle. Take a look at this: <iframe width="560" height="315" src="https://www.youtube.com/embed/1PjliCpQgXo?rel=0" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe> To make it very clear: This is different from the threads that are concerned with the nose wheel steering logic (NWS vs. NWS HI). AFAICT the HI/LO logic behaves as stated in the NATOPS manual. This is purely about the aircraft ground model. The only reason I pointed out the HI/LO modes in the video is because you can only reproduce this behaviour in the HI mode of the NWS. I was unable to reproduce this in any other model I own, still I think it is NOT Hornet-specific! I think it only SHOWS in the Hornet because it is the only model that has such huge NWS angles. I already have somewhat on an idea as to why the ground model produces this and how to fix it, but I'd like to hear you guys' unbiased opinion on this. Kinda like you shouldn't talk too much on "who wants to be a millionaire" before asking the audience :-D Dirty :-) Adverse Yaw during NWS Skid.trk

Bump Bump!! :-) Noone? Come on there must be someone using 3D Glasses. I am very interested in that. Maybe ED could give some Info about support for 3D Glasses. JaBoG32_Dirty

...sorry, I am unable to download any part, but am very interested. Can someone post a different Link? ...or am I doing something wrong here? Thanks,... Dirty :-)