[Easter Egg] DCS: JF-17 High Alpha Research Vehicle (HARV)

[LJQCN101]

Today we also decided to let you participate in our secret program, the JF-17 High Alpha Research Vehicle (HARV), which features thrust vectoring. Here's the way to activate such a function:

 

1. Include the text "JF17_TVC" in mission description (situations). So that it can be used in multiplayer if mission designers allow it.

2. On the FCS panel, switch FLT Test 1 and FLT Test 2 to ON, then push the FCS REC button.

 

Lateral stick and rudder command will be combined and sent to directional (yaw) TVC channel. Use them in conjunction to maximize yaw rate.

 

At any time you can turn off the roll-yaw augmentation at the FCS panel to resume direct control over the aileron, rudder and directional TVC channel. Longitudinal channels (including FBW and TVC) can not be turned off.

 

The TVC control law will gradually kick-in below 300 knots, and will be disabled when main landing gear WOW. (Note that there's no nozzle animations done for the external model, just pure physics and flight control.)

 

Enjoy your investigation, and don't forget to carry some smokers!

 

NOTES:

As one can tell right now the lateral and directional stability is very low above 27deg AOA, especially in transient wing rock region between 35-45 deg AOA. With single engine TVC there's no roll control at high AOA, so it's done by inducing sideslip to create rolling moment. In the TVC control law, the directional (yaw) channel uses roll-rate and sideslip feedback to provide artificial stability and dampening of wing rock. The longitudinal (pitch) channel achieves consistent pitch rate control, without being too sensitive. But still, do not create too much of yaw-rate onset when reversing turn direction, or the actuators can be saturated. Better to build up yaw-rate gradually and smoothly.

 

References:

[1] VISTA/F-16 Multi-Axis Thrust Vectoring (MATV) control law design and evaluation

[2] NASA TM104232, Research Flight-Control System Development for the F-18 High Alpha Research Vehicle

[3] NASA TM4772, An Overview of the NASA F-18 High Alpha Research Vehicle

 

Inspirations:

 

 

Update: Doing all the above procedure while leaving FLT TEST 2 at OFF will enable a line by line coded F18 longitudinal control law (OFP v10.1), which I implemented at around 2015 as an EFM practice, and just copy pasted the code to be another Easter egg. The reference document was NASA TM 107601. Be aware that the F18 FCS does not fit into the aerodynamics of JF-17 very well and you can tell by the oscillations at medium speeds. TVC will not be enabled in this mode.

Edited March 19, 2022 by LJQCN101
update

[Eaglewings]

Today we also decided to let you participate in our secret program, the JF-17 High Alpha Research Vehicle (HARV), which features thrust vectoring. Here's the way to activate such a function:

 

 

 

1. Set failure to only one channel of pitch rate gyro in Mission Editor.

 

2. Set failure to only one channel of AOA sensor in Mission Editor.

 

3. Enter the cockpit and wait for FCS warnings. You can check the FCS page for "X" symbol.

 

4. All channels of DFCS and EFCS should not be damaged.

 

5. On the FCS panel, switch FLT Test 1 and FLT Test 2 to ON, then push the FCS REC button.

 

 

 

The TVC control law will gradually kick-in below 250 knots. (Note that there's no nozzle animations done for the external model, just pure physics and flight control.)

 

 

 

Enjoy your investigation, and don't forget to carry some smokers!

This sounds unbelievable. Smelling some pranks here.

[LJQCN101]

I can assure you that it's really an Easter Egg, not a joke. :joystick:

[AeriaGloria]

If that’s true Im really happy. I must come up with funny video ideas

[-IRRE- Storfyr]

I've tested it, it works as intended :D

[Manuel_108]

Haha that‘s amazing. Just tried it

[AeriaGloria]

Wow so this how TVC flies.

 

J turns are HARD

[paco2002]

This is so funny, i cannot stop doing weird movements and breaking the laws of physics hahaha

 

*Next time, it should be able to turn off all the FBW system in pitch channel, that way you can have more fun!!!!

[LJQCN101]

*Next time, it should be able to turn off all the FBW system in pitch channel, that way you can have more fun!!!!

 

You actually can, by setting all channels of COMP and EFCS failure.

[AeriaGloria]

Loving this. Can you say how many degrees the TVC is? I assume 15 or 20 degrees? Very interesting seeing it’s limitations

[paco2002]

Loving this. Can you say how many degrees the TVC is? I assume 15 or 20 degrees? Very interesting seeing it’s limitations

Don't know, but I already have a mission with the JF-17 with TVC ready for when I want to make 180º turns in a second LOL.

 

I guess they're will be something like between 15-20º as you said

[Harlikwin]

I hate to ask, does this "Easter egg" work online? If so it will likely be abused.

[AeriaGloria]

Look at the OP. It requires two specific failures, so it’s up to mission designer

[paco2002]

I hate to ask, does this "Easter egg" work online? If so it will likely be abused.

If the Mission Editor adds the 2 fails, it should work on MP

[Harlikwin]

If the Mission Editor adds the 2 fails, it should work on MP

 

Ok, so if they don't it doesn't. Good. I was just wondering if there was a way for player to create those fails in game.

[paco2002]

Ok, so if they don't it doesn't. Good. I was just wondering if there was a way for player to create those fails in game.

Nope, not possible, only ME can

[Harlikwin]

Nope, not possible, only ME can

 

Good, I didn't want it turning into that whole F18 pull a circuit breaker situation a few months back.

[AeriaGloria]

Good, I didn't want it turning into that whole F18 pull a circuit breaker situation a few months back.

 

Even if you could force it it wouldn’t be much use. It might be good to catch someone but it only kicks in below 250 knots, so you’re a sitting duck

[CypherS]

Does it still work? I tried it just now but nothing changed in the flight model.

 

I set FCS_FAILURE_PITCH_RATE_GYRO_1 and FCS_FAILURE_AOA_SENSOR_1

 

FCS 1 and FCS 2 lit up and I put the switches to on and clicked FCS reset but nothing changed. Am I missing something?

 

 

Edit: Nevermind I'm dumb, was pressing the reset button instead of REC

Edited May 10, 2020 by CypherS

[Krag6]

I don't see any failures on JF17, is there an option i gotta enable to see failures?

[Tippis]

I don't see any failures on JF17, is there an option i gotta enable to see failures?

You have to set the skill to “Pilot” — failure triggers aren't available to MP clients, only to SP player pilots. Also, you have to have the failures enable in the DCS difficulty options and/or forced in the mission settings for them to activate properly.

[Krag6]

You have to set the skill to “Pilot” — failure triggers aren't available to MP clients, only to SP player pilots. Also, you have to have the failures enable in the DCS difficulty options and/or forced in the mission settings for them to activate properly.

 

Awesome thanks!

[Tiger-II]

I tried this, and can't see much use for it unless used as a last-chance maneuver when you already used your last-chance maneuver.

 

Interesting how she flies at very high AoA though. Feels like a delta.

[L0op8ack]

I tried this, and can't see much use for it unless used as a last-chance maneuver when you already used your last-chance maneuver.

 

Interesting how she flies at very high AoA though. Feels like a delta.

 

 

That's why it's called 'research'.

This is coded for FM test only, to verify your FM works as intended.

 

 

We found it's interesting, we decide to share it with you guys.

[AeriaGloria]

It’s socmuch fun! I love doing high alpha passes, spins, tumbles, using smoke, it’s a blast. Now I know the AOA Sensor only goes up to 60 degrees!