correct as is Harpoon enables radar before turnpoint, causes crash into terrain

[FalcoGer]

The scenario

When firing harpoons in RB/L mode they will cruise somewhat high up, so they get a good range on their radars. However once they see their target, they will then dive down to skim. The problem arises when the target is behind an island that is shallow enough to be seen over in cruise mode, but not when skimming. This causes the harpoon to slam into the ground. To counter that, you can enter a turn point for the harpoon to fly to first.

The bug

The harpoon will fly towards the turn point, but when it sees the ship near the target point it will turn, even before reaching the turn point. The harpoon will see the target behind a shallow island, dive down and turn towards the island, then crash into it.

The harpoon should only turn on it's radar after reaching the turn point and being a certain distance away from the target point.

To reproduce

1. Place a boat north of the easternmost point of Qeshm Island near the the harbor of Havadarya.
2. Create a turn point east of Qeshm's easternmost tip such that the harpoon will clear both Qeshm and Larak.
3. Launch a harpoon strike from Khasab using that turn point, Edit: use RB/L
4. Wait

Expected result

The harpoon will fly to the turn point, then turn towards she target point and seek the ship to engage it.

Actual result

The harpoon will fly towards the turn point, but before reaching it it will turn towards the ship and dive, causing it to crash into the island.

Why is this a problem?

This is a problem because it makes the turn point function, designed to avoid terrain or to attack ships from specific angles half useless.

Note

The turn point in the track is east of Qeshm at 40R DQ 31923 81048, but the missiles turn way early.

harpoon_flt_into_terrain.trk

Edited May 1, 2023 by FalcoGer

[BIGNEWY]

Not convinced this is a bug, Harpoon does not have terrain avoidance.

 

[MARLAN_]

1 hour ago, BIGNEWY said:

Not convinced this is a bug, Harpoon does not have terrain avoidance.

 

I think the main issue here is that the harpoon is not flying to its turning point before beginning to seek, which is a big deal, what if there are civilian ships that would normally be avoided by using a turning point, what if you were using the turning point to set a specific attack heading, etc?

I thin the crashing into the island is an irrelevant side effect that isn't the main issue.

[FalcoGer]

1 hour ago, BIGNEWY said:

Not convinced this is a bug, Harpoon does not have terrain avoidance.

 

Please read the report or at least the title. The point is that harpoons should fly to the turn point first, not that they don't clear terrain. The terrain is just to highlight the issue.

[FalcoGer]

Here is an illustration of the problem

The black lines illustrate what should happen. The red line is the buggy behavior we observe in game. I do not know the exact numbers, but the enable should happen some set distance before the target point and the self destruct some set distance after the target point. If the turn point is closer than that distance, the radar should turn on only after reaching the turn point, preferably also giving the missile to give some time to get on course, at least that's what I would do if I were to design such a system and that is also what I have seen modeled in other simulators.

The missile is launched in R/BL mode, the search and destruct ranges as well as heading to fly are set automatically by the system. But they still exist internally for the missile.

Edited May 1, 2023 by FalcoGer

[Hippo]

Quote

but the enable should happen some set distance before the target point and the self destruct some set distance after the target point

Is that right?  I had understood that with R/BL the distances were both measured from the launch point or the turnpoint (if used).  I reported a similar issue some days ago.

Edited May 1, 2023 by Hippo
I was being even thicker than usual when I posted this nonsense.

[BIGNEWY]

In the track you are not setting the search value? 

When I test it seems ok for me 

 

turn point harpoon.trk

[BIGNEWY]

I have asked another team member to check this also 

thanks

[oldcrusty]

11 hours ago, Hippo said:

Is that right?  I had understood that with R/BL the distances were both measured from the launch point or the turnpoint (if used).  I reported a similar issue some days ago.

 

I think the search start point in R/BL is measured from launch point. In BOL from the turn point if used.

I flew the similar mission to the one OP posted with the turn point on the grid he provided. The target ship was another 20 nm from the turn point (90 deg turn) I launched Harpoons over Khasab with the search set to 53.  Worked fine.

[FalcoGer]

13 hours ago, BIGNEWY said:

In the track you are not setting the search value? 

When I test it seems ok for me 

 

turn point harpoon.trk 148.01 kB · 3 downloads

I can't check this weekend. I'll get back to this on monday. I also wasn't aware of being able to set the search and destroy parameters in R/BL mode and thought that was only a BOL thing.

Thanks for looking into this.

Edited April 29, 2023 by FalcoGer

[Hippo]

Quote

I think the search start point in R/BL is measured from launch point. In BOL from the turn point if used.

Quote

I also wasn't aware of being able to set the search and destroy parameters in R/BL mode.

My apologies to both of you.  When I wrote my post I was thinking of and referring to BOL, but blundered in without taking enough time to read to your post properly.  You are quite right, those settings don't apply to R/BL.  I will amend my post shortly.

[Hippo]

I've taken a look at your track and (sorry) found it a bit hard to follow (there's a LOT of button pushing happening).  I attach a mission and a track, where the behaviour I see is as expected. 

I usually select the wp I'm going to use as a turnpoint in the hsi before selecting HPTP.

Why are you not using the SEA radar mode?

I have tried to reproduce the issue but have been unable to.

harpoon_01..trk harpoon_test.miz

Edited May 1, 2023 by Hippo

[FalcoGer]

2 hours ago, Hippo said:

there's a LOT of button pushing happening

At first I selected the HPTP to WP 0 accidentally for all 4 harpoons because I forgot that WP 0 is a thing in the hornet (usually isn't a factor since I don't do air starts), so I had to redo it for WP1 (which is the actual turn point).

2 hours ago, Hippo said:

I usually select the wp I'm going to use as a turnpoint in the hsi before selecting HPTP.

Of course I had to select WP 1 in the HSI/SA before asigning it as HPTP, I simply forgot so I had to redo it.

2 hours ago, Hippo said:

Why are you not using the SEA radar mode?

I then selected WP 2 as target point, which is easier to do for a test scenario than to mess with the radar. The ship was stationary and selecting the ship with the radar would've had the same effect anyway. So I simply used an easier to reproduce method that had the same effect.

Then I had to select R/BL mode for each harpoon, set each one to low cruise flight and also select every second one to pop up terminal.

 

3 hours ago, Hippo said:

I have tried to reproduce the issue but have been unable to.

I've noticed the bug a few times attacking a ship in the harbor north of Qeshm's eastern tip and it happened every time. My guess is that the scenario must be that the ship is in the harpoon's radar cone on the way to the turn point and that the ship must be relatively close to the turn point as well. In my case it was always just a slight bend, maybe 30° or 40°, not 90° and the ship was only ~10 miles from the TP and visible from the missile's route to the turn point.

If you want to test the same mission as I used, you can open the track file with 7zip and delete the track data and rename it to .miz. Track files and mission files are just zip files.

 

On 4/29/2023 at 4:52 AM, FalcoGer said:

I'll get back to this on monday.

I got home later than expected, I will look at this tomorrow.

Edited May 1, 2023 by FalcoGer

[Hippo]

On 5/1/2023 at 7:37 PM, FalcoGer said:

At first I selected the HPTP to WP 0 accidentally for all 4 harpoons because I forgot that WP 0 is a thing in the hornet (usually isn't a factor since I don't do air starts), so I had to redo it for WP1 (which is the actual turn point).

Of course I had to select WP 1 in the HSI/SA before asigning it as HPTP, I simply forgot so I had to redo it. (1)

 

The ship was stationary and selecting the ship with the radar would've had the same effect anyway. So I simply used an easier to reproduce method that had the same effect. (2)

If you want to test the same mission as I used, you can open the track file with 7zip and delete the track data and rename it to .miz. Track files and mission files are just zip files. (3)

 

(1) I wasn't critiquing your technique.  My implication was that this could be where the issue is (if not done in that specific order DCS gets "confused"), it might be worth trying.

(2) Just asking out of curiosity.

(3) Thanks, I didn't know that.  V useful.

[Hippo]

I just tried your mission again, and I saw the issue you described: the weapon activates and attacks the ship before getting to the turnpoint at WP1.

It's curious as this doesn't happen in the mission I set up.  Speculating, perhaps in your mission the distance between the turn point and the target is too short and the weapon is forced to activate early?

Edited May 3, 2023 by Hippo

[BIGNEWY]

Hi,

if you are setting the SEEK to MED it will start to search before the turnpoint, try using SML option for SEEK

Let us know if it helps

thank you