Harley Posted March 26 Author Posted March 26 3 hours ago, BIGNEWY said: Folks a reminder. Please do not attach, link or copy paste from real world manuals. Thank you I didn't know that was a problem. I downloaded that whole manual for free online. It's definitely widespread, easily accessible. Who knew? Sorry about that. But the point still remains.
ED Team BIGNEWY Posted March 26 ED Team Posted March 26 Just now, Harley said: I didn't know that was a problem. I downloaded that whole manual for free online. It's definitely widespread, easily accessible. Who knew? Sorry about that. But the point still remains. No worries, but sadly being online does not mean it doesnt have restrictions, in many cases they do and we have to be very strict about it here on the forum. 1 Forum rules - DCS Crashing? Try this first - Cleanup and Repair - Discord BIGNEWY#8703 - Youtube - Patch Status Windows 11, NVIDIA MSI RTX 3090, Intel® i9-10900K 3.70GHz, 5.30GHz Turbo, Corsair Hydro Series H150i Pro, 64GB DDR @3200, ASUS ROG Strix Z490-F Gaming, PIMAX Crystal
Harley Posted March 26 Author Posted March 26 47 minutes ago, BIGNEWY said: No worries, but sadly being online does not mean it doesnt have restrictions, in many cases they do and we have to be very strict about it here on the forum. Understood. Nobody wants to be blamed for disseminating potentially classified information. Those kinds of consequences are definitely unwanted. For clarity, the book is out there, am I allowed to reference the chapter? Meaning where to find the info, or is assuming that someone else also has this info still too close to "sharing"? Nobody wants problems, and I don't want to be that guy. Honestly, and I think it's pretty clear, I'm only trying to help, and I'm not a "beta tester", nor am I seeking that, but I do log plenty of flight time in the sim, and think I can contribute helpful info. That's all. Sorry to cause any issues.
ED Team BIGNEWY Posted March 26 ED Team Posted March 26 9 minutes ago, Harley said: Understood. Nobody wants to be blamed for disseminating potentially classified information. Those kinds of consequences are definitely unwanted. For clarity, the book is out there, am I allowed to reference the chapter? Meaning where to find the info, or is assuming that someone else also has this info still too close to "sharing"? Nobody wants problems, and I don't want to be that guy. Honestly, and I think it's pretty clear, I'm only trying to help, and I'm not a "beta tester", nor am I seeking that, but I do log plenty of flight time in the sim, and think I can contribute helpful info. That's all. Sorry to cause any issues. The information can not be shared here from that manual sorry. If you want to please DM me so we dont derail this thread. thank you 1 Forum rules - DCS Crashing? Try this first - Cleanup and Repair - Discord BIGNEWY#8703 - Youtube - Patch Status Windows 11, NVIDIA MSI RTX 3090, Intel® i9-10900K 3.70GHz, 5.30GHz Turbo, Corsair Hydro Series H150i Pro, 64GB DDR @3200, ASUS ROG Strix Z490-F Gaming, PIMAX Crystal
DummyCatz Posted April 16 Posted April 16 (edited) According to the NASA Technical Memorandum 107601 (https://ntrs.nasa.gov/citations/19920024293), a speedbrake-to-stabilator interconnect (Function 100) is incorporated to alleviate g transients for speedbrake extension/retraction. The interconnect command is on/off in response to speedbrake solenoid valve command. The magnitude of the input command air data scheduled. The interconnect command is lagged through a first order low-pass filter with the time constant scheduled with air data and as a function of speedbrake extension or retraction. The speedbrake extend time constant is less than the speedbrake retract time constant. The schema of Function 100: In which, Ri (pressure ratio) = dynamic pressure / standard atmosphere pressure. As you can see, the delta HT (horizontal tail) compensation is only active in a range of Ri from 0.4 to 0.96, which roughly corresponds to 0.7 - 1.1 Mach. Other references: https://www.semanticscholar.org/paper/Development-of-a-mathematical-model-that-simulates-Rojek/0fde51d56d310669dd67ae8520a0650989a91156 https://archive.org/details/developmentofmat00roje/page/n3/mode/2up distribution unlimited. Edited April 16 by DummyCatz 1
Muchocracker Posted April 16 Posted April 16 8 hours ago, DummyCatz said: According to the NASA Technical Memorandum 107601 (https://ntrs.nasa.gov/citations/19920024293), a speedbrake-to-stabilator interconnect (Function 100) is incorporated to alleviate g transients for speedbrake extension/retraction. The interconnect command is on/off in response to speedbrake solenoid valve command. The magnitude of the input command air data scheduled. The interconnect command is lagged through a first order low-pass filter with the time constant scheduled with air data and as a function of speedbrake extension or retraction. The speedbrake extend time constant is less than the speedbrake retract time constant. The schema of Function 100: In which, Ri (pressure ratio) = dynamic pressure / standard atmosphere pressure. As you can see, the delta HT (horizontal tail) compensation is only active in a range of Ri from 0.4 to 0.96, which roughly corresponds to 0.7 - 1.1 Mach. Other references: https://www.semanticscholar.org/paper/Development-of-a-mathematical-model-that-simulates-Rojek/0fde51d56d310669dd67ae8520a0650989a91156 https://archive.org/details/developmentofmat00roje/page/n3/mode/2up distribution unlimited. Alleviate but not remove. This cited report is from 1986. And the pitch bobble is still noted as a behavior in a 2006 dated NATOPS. Idk what point you're trying to make here.
DummyCatz Posted April 17 Posted April 17 (edited) 15 hours ago, Muchocracker said: Alleviate but not remove. This cited report is from 1986. And the pitch bobble is still noted as a behavior in a 2006 dated NATOPS. Idk what point you're trying to make here. OP asked if there is a definition for the correlated degrees of travel that the pitch correction input from the elevons is supposed to be. I gave the answer. Sometimes NATOPS doesn't give the full picture. I'm not sure what you're trying to argue here. I am not the one who disputed the word 'Alleviate', as with all open-loop linear compensation logics. The point here is to provide an overall system description when NATOPS cannot be posted on the forum, and the fact that it only works in a limited range of Mach Numbers (high subsonic speeds). It can be inferred that the pitch bobble is not that pronounced in low subsonic speeds, where it doesn't require compensation by the FCS. Also, the interconnect command is on/off in response to speedbrake solenoid valve command, meaning it's either on or off in response to the opening and closing action, but not actual positions. This clarifies OP's doubt. The cited NASA report is for FCC OFP v10.1, and the logic should be the same from v10.1 to v10.7 as there's no documented change in speedbrake-to-stabilator interconnect function. Edited April 17 by DummyCatz 1 1
DummyCatz Posted April 19 Posted April 19 @Harley Just tested with DCS 2.9.15.9408, the speedbrake-to-stabilator interconnect logic is still working at low speeds, which contradicts Function 100. You can confirm this by using active pause and then experiment with speedbrake commands at different Mach Numbers. In this case, the g-transient is purely caused by the FCS itself, and is a wrong behavior. 1
Harley Posted May 14 Author Posted May 14 On 4/18/2025 at 8:28 PM, DummyCatz said: @Harley Just tested with DCS 2.9.15.9408, the speedbrake-to-stabilator interconnect logic is still working at low speeds, which contradicts Function 100. You can confirm this by using active pause and then experiment with speedbrake commands at different Mach Numbers. In this case, the g-transient is purely caused by the FCS itself, and is a wrong behavior. It seems to be getting worse every time they touch it. It's raised the debate for me to even report some of these things or not. But, at least it's being worked on. I'm sure that the "bobble" they refer to is a very slight but noteworthy behavior, needed for precision. I love the posts you've made up there about this. I have questions. 1. The engineers ad McD/D definitely tried to minimize the forces exerted with the speedbrake's force by integrating an FCS counter. I think you've made the argument pretty clear with your attachments up there. I need to look again, but it looks like a force can be calculated with the area of the speedbrake panel, airspeed, angle of deflection, ambient air density, and then the total expected FCS counter/retrim, and the only thing that needs to be inserted into the equation is the time to deploy for both. Can that be assigned with the model as it is? Also, if that has been done already, because DCS devs are pretty thorough, is it unrealistic to ask to minimize the effect if all is correct as is? Something tells me it's not. Can you imagine how badly this will mess with a precision approach when trying to correct for overspeed on final? I need to try that. Even ACLS may have issues with that. I dunno. I suppose I'm not as in depth with the numbers as others, but it seems intuitive enough that the attempt to counter the speedbrake nose up input has been made, but the implementation hasn't been good yet. It seems that if the system was integrated, then it should work little better than current.
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