Super Grover

Hey DoorMouse, Next time your INS fail, could you note precisely what steps you took to repair and restart? I know that the code for the repairs exists and should be working, but maybe we're missing something here. Please note that both the IMU and the AHRS may require re-alignment/re-erecting, and this may require some time.

Resetting counters is just for RIO to track the number of countermeasures left. The most important action is to reset the programmer - hold the reset switch in RESET for at least 5 seconds. From the manual http://www.heatblur.se/F-14Manual/general.html#programmer : Jester does it each time after reloading the launchers and taking off.

The resolution is limited by the pod not by the display.

Hey Bestandskraft, It often happens that the NAVAIRs are imprecise, and this seems to be the case here too. Indeed, the TACAN transmitter/receiver on the F-14 didn't have a dedicated bearing/beacon antenna installed. We checked more detailed specifications and diagrams. The conclusion was that when a valid bearing signal is received, it should be displayed, as it didn't require any additional processing versus land-based TACAN.

VC is the magnetic variation calculated inside INS/AWG-9 - the program takes the magnetic North from the AHRS and the true North from the IMU/INS, compares the two, and the difference is the VC. However, on a carrier deck, the magnetic North reading can be severely affected by different sources of the magnetic field, and hence the difference can get beyond that 2°. Once airborne, the VC should slowly recover. Or alternatively, to speed up the syncing process, the pilot can press and hold the HDG pushbutton on the compass panel. One thing to remember - the aircraft must be in a straight unaccelerated flight, otherwise the acceleration gate wouldn't let the sync happen.

Yes, POINT can be initiated only in WHOT, and it is not a bug. However, once POINT is engaged properly, you should be able to switch to BHOT, and again, it's not a bug :) .

Hey Ramsay! Actually, you weren't precisely on the radial 117° (297°) but probably around 118-119. The deflection needle isn't accurately aligned, and the direction to the TACAN station (that little arrowhead) is slightly shifted to the right from your heading. You are right that the sensed magnetic north direction and the declination shouldn't affect TACAN radial readings. However, we the TACAN itself has some limited accuracy, and according to the specification for the AN/ARN-84(V) the error can be as large as between 0.5° and 2.0° for the digital bearing and between 1.0° and 2.5° for the analogue bearing. The error depends on the strength of the signal received. We measure the signal reception, and we model the errors, so it is possible that in your case that's the reason for the difference you observe. BTW these TACAN bearing measurement errors are the main reason why TACAN fixes for the INS may introduce INS errors even more significant than before the fix.

Thanks for the report. I'll look closer, what can explain your observations and if the system behaviour is correct. However, I have to apologize that my schedule for the next week is full so it may take me a little longer. I'll let you know when I have something on this.

Thanks for the comment. The display MODE switch doesn't work as a filter, but it is used to prioritize threat categories, as indicated in the manual http://www.heatblur.se/F-14Manual/general.html#controls . It means that it may impact what is displayed only when the total number of threats detected is greater than 15, or greater than 6 in LMT. I hope this short explanation helps. Please, feel free to ask more questions if something is unclear. Also, if you still find that some RWR behaviour is a bug, please provide us with a more detailed explanation of what you observe and what is the behaviour you would expect from the device.

Also, check if there's only one carrier using ICLS - if there is more, the signal from them may interfere and result in unstable ICLS signal or even make tuning the ICLS impossible. The longer version of this story: it is possible to have multiple carriers using ICLS, but remember to set different channels to the carriers sailing close to each other. Additionally, please remember, that channels that are 10 channels apart share one frequency, so two carriers operating together and using channel 1 and channel 11 respectively will also make ICLS operation disturbed or impossible.

888.888 is displayed in the test position. Try lowering the brightness a bit.

Yes, POINT can be established in WHOT only. Or rather, to be more precise, it can be engaged on objects that appear white on a dark background (no matter if it's WHOT or BHOT). Once POINT is successfully engaged, it should be possible to change the polarity. However, due to the limitations of the simulation, it is simplified to: you can go into POINT only in WHOT.

Quite possible. You can try using a wider field of view. Hmm, I'm not exactly sure how area track works technically, but if you try to area track a position 100m next to a ship, with the ship already being on camera it might use the ship as a reference. I'm entirely specualting here though. Yes, that's how it should work. Under good weather conditions, the area track should always work when used on the ground (within some reasonable distance), and over water only if there's another contrasting object or shore visible and close to the cross. This required some tuning, so if you find a situation when the tracking should work but it isn't (or shouldn't work but it is), please send me a screenshot, and if possible the mission, and I'll re-tune the algorithms. Of course clear weather only.

In the INS mode, the two headings - the true heading from the INS/IMU and the magnetic heading from the AHRS - are completely independent and never synced. They are used together to calculate the magnetic variation value.

First of all, the AHRS can't be considered as a reliable and precise enough source of magnetic heading, not mentioning true heading which for which the performance is even worse. That's why the "MV" acronym appears on the TID only after the difference between the calculated magnetic variation, and the entered magnetic variation is greater than 5 degrees. Entering own heading is useful when performing an in-flight reset of the IMU. The procedure is to: 1. Set NAV MODE to OFF. 2. Press PRGM RESTRT (not simulated yed). 3. Set NAV MODE to IMU/AM. 4. Fly straight and level for 3 to 5 minutes. 5. Enter own true HDG. 6. Enter winds. 7. Enter own LAT and LONG (from wingman, carrier, AWACS). The INS mode would not be available, but it should allow using the IMU/AM. Answering Looney's questions. A. Why does the INS calculates a groundspeed when own aircraft heading is set to, in this case, 62 degrees? I may have an idea of the reason for such a high ground speed drift, but it's difficult to say it for sure without seeing the debug data. However, I can try explaining it. Earth rotates at a rate of 15° per hour, and Earth surface (with aircraft parked on it) moves at ~600 kt (for latitude ~45°). The INS must adjust for such a movement, and accounts for it in the algorithms and applies necessary corrections to the IMU platform. When you input a wrong heading, the INS applies wrong corrections, and the IMU is not levelled correctly any longer. In consequence, and the INS starts sensing gravity as a false horizontal acceleration, and it starts drifting very quickly. With own heading error of 62°, the INS mixes East-West with North-South so heavily, that it can easily result in false ground speed readings at the level of Earth surface linear speed. B. Why didn't the system switch over to a backup mode as the GS and TAS units it got were vastly different? The INS itself has limited means of detecting a failure like this. GS and TAS can be (and usually are) different because of wind. And wind can be as strong as 100kt (this is the wind speed at FL300 over the Great Lakes from today). Of course, 600kt is much less probable :D, but we have to remember that it is a system from the early '70s, and it required a bit more attention from the operator when compared with modern INS.

Hey! LANTIRN has its own INS, and it uses GPS data to align/correct the INS. Also, it can read waypoint coordinates from AWG-9. However, I think that the way you use VIS FIX may be wrong. With CAP drum set to NAV category, the VIS FIX button is used to apply a shift to own INS position based on a position of a waypoint you can easily identify visually. You have to press it when overflying that waypoint. It means that the FIX procedure doesn't change the coordinates of the waypoint, but only updates the INS. That's why you observed no change of the QWP1 on the LANTIRN screen. The only way to update a waypoint position is to enter new coordinates manually or drag it with the HCU.

If I remember correctly (I would have to dig in the documentation), the CADC doesn't use any altimeter settings (just plain 29.92). Altimeter setting (correction for non-standard pressure) is applied in the altimeter.

It's possible that the sliding can cause that, but I have to investigate it further.

Pulling G is not required to accumulate error. If the INS is misaligned, it'll accumulate error even when staying still on ground.

The INS has only a limited ability to detect alignment errors. More often it would be just true heading being wrong, and you can only verify it by checking the true heading through CAP+TID (or mag var, but that you'd expect to be off on a carrier). You can't tell if the true heading is wrong by just observing the BDHI or the VDI/HSD/HUD, because they are all magnetic and by design they are default driven from the AHRS. Moreover, even with a very bag alignment, initially the INS will show the correct position, as it's initialized at that position and the initial velocity is zero. However, it will catch some false velocity very quickly. There's another possibility; if it was a multiplayer session with some heavy lags/desyncs, the INS could have sensed large differences between own velocity and the carrier velocity through SINS, leading to significant alignment errors.

It depends on how you fly the aircraft as an acceleration greater than 75 knots/minute disables slaving the directional gyro of the AHRS to the magnetic field from the magnetic azimuth detector (MAD). This means that it's very easy to never let your AHRS resync. You have to fly level and constant speed, and this is often a challenging task when those two engines are just waiting to give you more power and more speed, and when the pilot is looking for the opportunities to fight and keeps maneuvering. @sLYFa Jester knows the mag var from the kneeboard :) and he enters it on startup, after switching the NAV mode to INS.

The F-14 doesn't have any magvar database. It uses the AHRS magnetic heading together with the INS true heading to compute the magnetic variation. The INS knows how to draw true north during alignment from observing the gyros drift.

Assuming that all INS-related devices were OK, the first thing to check would be the COMPass panel (pilot's right side console) http://www.heatblur.se/F-14Manual/cockpit.html#compass-control-panel Fly straight, level, constants speed at low AOA and check the display marked as 1 - SYNC IND. If the needle is shifted from the centre, the AHRS has drifted/aligned to a wrong magnetic heading and caused that MV error. Press and hold that HDG PUSH button (5) until the needle moves back to the centre. If the needle doesn't move, you're probably turning/climbing/diving/accelerating/decelerating - just check your speed and attitude and try again.

Just FYI, the bearing accuracy of digital readout of the AN/ARN-84(V) - the TACAN - is between 0.5° (for signals stronger than -82 dBm) and 2.0° (below -90 dBm). And we model that in our TACAN receiver. What you observed and recorded in the video is that TACAN inaccuracy together with possible mag var drift.

From the picture you posted, it looks that you are ~45NM from the TACAN, which is far for TACAN FIX. At that distance, the calculated mag var errors and the measured TACAN bearing inaccuracy (don't underestimate this) may introduce significant errors to your position updates. In other words, what you see on the TID, the delta, it's NOT the difference between the aircraft true position and the current position. It's the difference between what the INS thinks is the true position and the current position. Back to manual delivery, we don't need to post any manuals here, but it would be useful to understand what you want to achieve. Because from your description it looks that you may be trying something that the F-14B couldn't do.