Interesting Article on Low-Cost Fighters

[n57flyguy]

Great jet, the F-20

What is L (laser) -INS? Similar to 'regular' INS?

Edit: the problem is it was too efficient for the USAF thats quite an ops tempo they reported.

 

[Pilot Fighter]

What is L (laser) -INS? Similar to 'regular' INS?

Edit: the problem is it was too efficient for the USAF thats quite an ops tempo they reported.

Ring laser gyro as opposed to old mechanical INS.

 

[n57flyguy]

Ring laser gyro as opposed to old mechanical INS.

Thank you. Is INS used as a primary means of navigation in the Navy? Are they singular or dual or even triple systems? I have often heard a few classic platforms still utilize traditional FTF methods.

 

[Pilot Fighter]

Thank you. Is INS used as a primary means of navigation in the Navy? Are they singular or dual or even triple systems? I have often heard a few classic platforms still utilize traditional FTF methods.

I think all the carrier-based aircraft have retained INS (CAINS II or III) with GPS backup or GPS correction (with encrypted PPS) modes for route navigation these days. The S-3 had a pretty sophisticated INS and basic GPS, as well as TACAN.

 

[ryan1234]

Thank you. Is INS used as a primary means of navigation in the Navy? Are they singular or dual or even triple systems? I have often heard a few classic platforms still utilize traditional FTF methods.

Obviously not the Navy but we have an EGI (Embedded GPS / INS combined with a Kalman filter). The INS uses the RLG (Ring Laser Gyro) and can use precision velocity updates from the radar to determine the aircraft velocity relative to the surface. There are ways to update the INS and different types of modes for navigation that can get pretty complicated.

 

[Pilot Fighter]

Obviously not the Navy but we have an EGI (Embedded GPS / INS combined with a Kalman filter). The INS uses the RLG (Ring Laser Gyro) and can use precision velocity updates from the radar to determine the aircraft velocity relative to the surface. There are ways to update the INS and different types of modes for navigation that can get pretty complicated.

S-3 had three modes, if I recall correctly. INS, INS+Doppler, and Doppler.

 

[ryan1234]

S-3 had three modes, if I recall correctly. INS, INS+Doppler, and Doppler.

It's probably similar. It just uses a Doppler range rate to find the velocity, but it's a separate mode of the radar in A/G (like RBM, HRM, etc)

 

[MikeD]

Obviously not the Navy but we have an EGI (Embedded GPS / INS combined with a Kalman filter). The INS uses the RLG (Ring Laser Gyro) and can use precision velocity updates from the radar to determine the aircraft velocity relative to the surface. There are ways to update the INS and different types of modes for navigation that can get pretty complicated.

I remember when EGI was brand new. 4 minute time-in instead of the 16 minute our old INS required.

 

[Pilot Fighter]

I remember when EGI was brand new. 4 minute time-in instead of the 16 minute our old INS required.

16 minutes - could you IFA or used stored data?

 

[MikeD]

16 minutes - could you IFA or used stored data?

16 minute was the optimal. 8 minute was minimum. It had an air align mode, but that was iffy and required a series of check turns and the like to get it oriented, but even that had to be based off a previously known grund alignment. Was a straight gyro INS, no GPS.

 

[Pilot Fighter]

16 minute was the optimal. 8 minute was minimum. It had an air align mode, but that was iffy and required a series of check turns and the like to get it oriented, but even that had to be based off a previously known grund alignment. Was a straight gyro INS, no GPS.

S-3 was 4 minutes for shore ops. On the boat, alignment was via data link or cable. GPS correction was not integrated into INS until later upgrade. Our GPS backup was a handheld Magellan 5000 and a pocket full of batteries.

 

[hook_dupin]

Fiber optic gyros are the new hotness in the INS world....

At the small end, MEMS-based gyros are becoming more accurate.

 

[///AMG]

Our oldest jets (well the ones that came after the dawn of GPS) had EGI. It wasn't a very good system, as it never corrected for initial position error......so if your alignment places you a mile from where you actually are when you get the jet started, you will be a mile off for the rest of the flight. Granted it shouldn't theoretically get worse, given the GPS updates. MAGRS is a much better system

 

[Pilot Fighter]

Our oldest jets (well the ones that came after the dawn of GPS) had EGI. It wasn't a very good system, as it never corrected for initial position error......so if your alignment places you a mile from where you actually are when you get the jet started, you will be a mile off for the rest of the flight. Granted it shouldn't theoretically get worse, given the GPS updates. MAGRS is a much better system

Will you see JPALS before you retire?

 

[///AMG]

Will you see JPALS before you retire?

that sounds familiar

 

[Pilot Fighter]

that sounds familiar

Joint Precision Approach and Landing System. They have been developing for years, will probably take another decade for implementation.

You keep flying. Somebody will let you know if you need to know anything new.

 

[ryan1234]

Fiber optic gyros are the new hotness in the INS world....

At the small end, MEMS-based gyros are becoming more accurate.

I was just reading an article about how the newest MEMS are only about 20-30% less performance than FOGs without GNSS and cost about 30 times less.

 

[///AMG]

Joint Precision Approach and Landing System. They have been developing for years, will probably take another decade for implementation.

You keep flying. Somebody will let you know if you need to know anything new.

yeah half the time they can't get an ACLS lock on me and keep babbling about it until the ball call.........so i would rather have nothing than more personally. ICLS...why is that so hard to understand........

 

[n57flyguy]

Obviously not the Navy but we have an EGI (Embedded GPS / INS combined with a Kalman filter). The INS uses the RLG (Ring Laser Gyro) and can use precision velocity updates from the radar to determine the aircraft velocity relative to the surface. There are ways to update the INS and different types of modes for navigation that can get pretty complicated.

Thanks Ryan and @PilotFighter, so the basic understanding I am gaining is that INS is used as a redundancy for aircraft navigation.

I got curious and asked a former F4 driver aswell:

Yes, we had an INS, but did not use it very often. Tacan and ground and on-board radar did most of our navagation for getting from point A to B, with INS as a back-up. Inst approaches were GCA’s (precision approach) and when not available, we used Tacan approaches with our own on-board radar for back-up. GCA’s are wonderful. No problem with 100 foot ceiling and 1/4 mile vis.

 

[MikeD]

Thanks Ryan and @PilotFighter, so the basic understanding I am gaining is that INS is used as a redundancy for aircraft navigation.

I got curious and asked a former F4 driver aswell:

Most military INS in fighter jets, aren't approved for primary navigation in the NAS, hence the F-4 pilots comments to a degree. And most of these same jets can't file /G or /R. Many are still a /P due to their primary navigation means.