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Curly

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  1. The 570-100 PRINCIPLES OF OPERATION INTEGRATED FLIGHT CONTROLS NAVY MODEL F/A-18A/B/C/D 161353 AND UP
  2. I felt the need to describe the entire flight contronl system in detail because, they way you talked about it made it seem like that the force sensor was the singular input. It is not. Nor is it the largest input. The CAS and therefor the stick force transducer, can command at most +-10 degrees of stab. The example was meant to be an illustrative overview of the FCS operation not a literal account of the air data schedule. Re "The FCS isn’t responding to inputs until the pilot overcomes the breakout force and displaces the stick. As is illustrated in this in this docu
  3. The Stick force sensor is integrated in the F-15 FCS as a way to detect command error. That is the difference between the command G (stick position) and the actual G. The hydro mech system of the F-15 is geared to deliver a consistent G per stick displacement based on the air data (dynamic and static pressure). There however areas of transient response where the hydro mech system alone will not deliver the command G. This where the CAS system comes in play. The stick force sensor in a way double checks what the pilot is asking for and moves the stabs via the CAS servos to meet the
  4. In short the FCS won’t accept input unless it’s greater than the breakout force. However, there are a few thing to unpackage and explain here. First, the stick in Hornet isn’t force sensing. A series of LVDTs sense the movement of the stick and communicate this to FCS computer in the terms of voltage. So the input to the FCS is based on the position of the stick. Not the force exerted on the stick. There is also a series of springs which provide resistance to the stick's movement. This is called the feel system. When you use the trim buttons, The feel system moves the stick.
  5. You don't understand the content of those papers. They are not referring to a physical simulator with a joystick. So there isn't a "different sensor for stick travel". They're making a computer program to replicate the FCS and the aerodynamics. The inputs are data typed into program, then iterated and output as set of variables, Matrices in the case of DTIC paper. Again, no joystick. The NASA simulation was designed to produce trim shots based on stick position, thrust, ect. For the results to be valid they had to use the actual FCS and it’s governing functions. Which is why they went to su
  6. TLDR: If you’re looking to model your stick forces via a cam profile. Probably best to model the F-15’s and skip the breakout force dead zone. See Pages 40-43. https://www.nasa.gov/centers/dryden/...ain_H-1073.pdf If your stick doesn’t have an adjustable force profile, just leave it be It’s probably fine. Yes stick forces are lighter in the roll, that pretty typical for an FCS. If you’re looking to shape the cam profile here are a couple things to keep in mind. This gets complicated because your trying to model something that may or may not be modeled. Unless the breakout forces are
  7. There are few really good open source documents on the Hornet’s FCS. The best and most recent is from NASA. It describes the system as follows https://ntrs.nasa.gov/archive/nasa/c...9920024293.pdf “The pitch CAS uses a pilot commanded longitudinal stick position input as a command to the CAS. The forward path gain is air data scheduled (Function 32A) to yield a uniform initial pitch acceleration response for sharp inputs. The CAS feedback parameters are a blend of air data scheduled pitch rate (Functions 40 and 68, normal acceleration, and angle of attack. Pitch rate and normal acceleratio
  8. The Take off trim system on the Hornet is unique. The trim system bias the feed forward integrator to capture a specific AOA, once the system detects weight off wheels. Pressing the takeoff trim button sets the bias to 4 degrees of Angle of Attack. The carrier takeoff trim settings of 16 to 19 degrees, sets the system to capture 12 degrees of AOA. The system is designed to pitch the aircraft at a rate of 12 degrees per second, a form of auto rotation, once the weight is off the wheels. With increased gross weight, additional trim is required to get the aircraft to rotate. The system is limi
  9. Max AOA at CL max at 15k ft is 34 degrees. https://ntrs.nasa.gov/citations/19950007836 The G limiter is what is preventing AOA greater than 34 degrees. Corner is where CL max meets the airframe limitation. In this case the 7.5 g limiter. CL max for the airframe is 1.8 at an AOA of 40. To achieve that AOA you need to be below the G limiter. https://www.nasa.gov/centers/dryden/pdf/88489main_H-2149.pdf While There is no AOA limiter on the airframe. Pitch rate, NZ and AOA feedbacks will dampen pitch rates. It looks to that what you’re bumping into either the NZ limiter or ag
  10. I'm not trying to answer for Lex, but even with the RUG 2 upgrades, I wouldn't expect the world. The displays in the cockpit are 480 by 480 pixels. Even with the increased capabilities of the SAR, you'll basically looking blobs. 1 meter resolution is still very grainy and given the display size the images wont resolve clearly. Even down to .3 meter resolution it's is difficult to distinguish targets. The ultra high rez stuff that looks like photos, is likely 10 centimeter and below. This is a set of targets at a .3 meter / 1 foot resolution at 128 by 128 pixels Can
  11. From the 2001 training plan. https://www.globalsecurity.org/military/library/policy/navy/ntsp/f-18-a_2001.pdf Page 19, In FY98, Lot XX series F/A-18C/D Aircraft were delivered,integrating the Phase II AN/APG-73 RUG, ATARS, Joint Direct Attack Munitions, Joint Stand Off Weapon, Initially The APG-76 was limited to a .8nm / 1.5 km patch with a resolution of 3 meters / 10 feet. Slightly less than resolution than the APG-70. Around the same time it recvived similar upgrades to 70 to achieve those resolutions.IE Upgardes to the IMU and more signal processing power. https://www.r
  12. The APG 70 is capable of a 4 foot / 1 meter resolution map over an area of .33 nmi. This made it possible to distinguish a SCUD TEL from a MAN truck and a ZIL command van 150 feet apart. https://apps.dtic.mil/dtic/tr/fulltext/u2/a347534.pdf 8 foot / 2.5 meter resolution is available up to 20 nmi https://apps.dtic.mil/dtic/tr/fulltext/u2/a319223.pdf The Phase 2 RUG was delivered on all lot 20 aircraft. I think we're limited to a 16.4 foot / 5 meter resolution over a 1.2 nmi range in DCS. If you keep the target designated in EXP 2 the resolution will increase until the
  13. The IFLOLS is about 500 feet from the ramp. So Aft of the ramp the light appears larger than the size of lenses on the IFLOLS. At the ramp the meatball would appear about the size of lens on the IFLOLS. In real life it would move in same analog fashion as the gauge. The ball would appear between the lenses on the IFLOLS as you moved up down the glide path. When you are on glideslope at the ramp you are looking at light from the top and bottom of the 6’th and 7’th lens at the same time. Let’s do a little thought experiment to illustrate the point. Let’s say the 6 and 7’th lig
  14. The analog format of the indicator is actually how the IFLOLS works. The beam of light of light emitted from the display is very narrow close in. It diffuses wider the further away from it you are. At around 500 feet the light appears to fill a single lens. Once you get 20 feet from light source, the line is about an inch high. What’s really wild is that there is no centered lens. There are 12 lenses, hence no middle lense. The datum light are between the 6 and 7 lens. So when you’re looking at on glide slope, you’re seeing light from both the 6 and the 7 lens at the same tim
  15. There is a pretty good case in the public literature for larger detection ranges from the apg-63. In game, I can resolve MiG 29’s (5m^2 RCS targets) in RWS high perf, at about 60 nautical miles (111 Km). 86-70 Nm in RWS seems theoretically possible given the publicly available data on the radar. This is a publicly available DOD report on the radar. Max Theoretical range in High Pref RWS is 78 Nm (144 Km). The US tends to use 5M^2 for fighter sized targets in it’s reports. https://apps.dtic.mil/dtic/tr/fulltext/u2/a142071.pdf The APG-63 dish size is 36 inches in di
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