Hellfire LOBL/LOAL and the 4 Trajectories

[AvroLanc]

I'm not an SME or anything, but one aspect of Hellfire employment that needs clarifying is the understanding of the When and Why of Hellfire LOBL/DIR/LO/HI modes. I see a lot of online streams and tutorials that either suffer misconceptions or inaccurate teaching of these modes. 

The first thing that needs emphasizing - There are four possible Hellfire trajectories; and they all work nicely in DCS:

LOBL Trajectory

LOAL DIR Trajectory

LOAL LO Trajectory

LOAL HI Trajectory

I think the one overriding misconception people have is that DIR is the 'LOBL mode'. This is not the case. DIR is a LOAL configuration and has it's own trajectory. The system will default to LOBL whenever the missile seeker detects laser energy on the same CODE it's set for. I.e you don't need to be in DIR to get a LOBL launch...just lase with the matching code and you'll get LOBL/Large constraints box. The missile will then adopt it's own unique flight path trajectory that is different from either DIR/LO/HI. I.e You can get LOBL with LO/HI traj set as well.

So what is DIR trajectory? It's used for a LOAL launch, and as the name implies the missile follows a more direct / flatter flight path to the target. This has some advantages. With DIR NORM or DIR MAN (and later RIPPLE), with empty HAD weapon inhibit field, just pull the trigger and fire. You'll get a LASE 1 TARGET message in the HAD, and you should lase at about this point. Otherwise it's the same as LOBL in that the constraints box is driven by the TADS Line of Sight (you don't need to worry about an ACQ Source point like in LO and HI). For this reason DIR is very useful. 

Advantages of LOAL DIR:

• Most direct and flattest missile flight path, means marginally shorter TOF.
• Approx 300-400' max missile height above own aircraft, even at max 7-8km range, compared to approx 200-600' max height for LOBL at same range (but LOBL traj is range dependent).

When to use DIR:

• When you have a direct LOS to the target
• Low trajectory means it can be used on a low cloud base day (I don't think DCS models laser spot loss in clouds yet)
• The when BACKSCATTER message prevents a launch in LOBL, stop lasing and fire LOAL. (BACKSCATTER message is in and works, but again I don't think DCS is modelling false lock ons, not sure what's being simulated exactly)
• If the target has a Laser Warning System, the delayed lase gives them less time to react, compared to LOBL. (Again, DCS doesn't really model this yet for AI)

 

When to use LOAL LO and HI:

LO and HI should only really be used when you're sitting behind a mask or don't otherwise have a direct Line of Sight on the target. LO should have a max 800-1000' height and HI 1400-1600' feet max height.(Approx DCS testing/experiments). So choose one depending on the size of the hill or mask you're hiding behind.

You shouldn't really ever be using LO or HI if you can see the target directly. There's no advantage. Some talk of a higher/more vertical impact angle for top attack. But if you look at the actual impact angle in 3D, it's not really that different, especially at longer ranges. HI doesn't turn Hellfire into some kind of next gen top attack weapon, it's not like it's coming in near vertical or anything.

• Use when you don't have a direct LOS, you're hiding behind a mask.
• The target location is stored as the current ACQ SOURCE.
• You can lase either remotely, in which case you don't need to expose yourself or unmask at all....use another player or the AI JTAC to lase.
• Or you can lase autonomously, by firing behind the mask and timing a bob-up maneuver to bob-up 50-70ft and lase with a good 10 seconds of lase time on target. Use the HF TOF and LASE 1 TARGET messages to judge it. Even using George AI works using this method. And it's satisfying.
• If you get good you can fire 2 missiles behind the mask and lase each in turn. Just slew carefully.

Disadvantage of LO/HI:

• All of the trajectories have minimum ranges; LOBL about 500m, DIR about 1500m, LO about 2000m, HI about 3000m. (Approx DCS testing/experiments)
• This is why you see many players using HI and complaining that the missile never hits. It just overflies without picking up the laser spot, even with a fairly early lase. Use LO and HI at longer ranges and lase early on, when you get the LASE 1 TARGET message. 

 

When to use LOBL:

When none of the other considerations apply and you just need to shoot with a direct LOS, high cloud ceiling, and want the easy life. Low threat, low complexity.

If any SME's want to tell me that's all wrong then please please do, as I say I don't really come with any real experience, just enthusiasm. Note that all the heights and ranges I've stated are observations from within DCS itself.

 

Edited March 30, 2022 by AvroLanc

[Sydy]

Nice post, thanks!

[MrReynolds]

Another +1

I've fallen into the trap of firing a HI attack and seeing that baby fly off into the distance not spotting the laser.

It's as if it's not even trying to look at the AQ source.....(which in NO way would be pilot error.  NO....)!

[Marklar]

3 hours ago, AvroLanc said:

Even using George AI works using this method. And it's satisfying.

As of today George AI won't store target location so you have no waypoint to select as ACQ SOURCE. Also how do you instruct George to start lasing after you launch a missile in LOAL mode?

Edited March 30, 2022 by Marklar

[poochies]

I find that hitting a tank straight on facing me  in DIR mode doesn't do any damage switching to LO kills them every time so coming down from higher angle definitely helps....

[Nevyn]

Very helpful, thanks boss.

[AvroLanc]

1 hour ago, Marklar said:

As of today George AI won't store target location so you have no waypoint to select as ACQ SOURCE. Also how do you instruct George to start lasing after you launch a missile in LOAL mode?

 

When in LOAL DIR George will lase after he fires. He will wait until he gets the LASE 1 TARGET message. 

When in HI or LO, I swap to the front seat and play from there. In theory you could swap back to rear after making sure the ACQ SOURCE is set, but I stay there for the whole engagement. 

[Frederf]

Thank you for this.

Does DIR/LO/HI change the flight profile for LOBL launches or are all LOBL launches the same flight profile regardless of trajectory setting? Does an e.g. LOBL/HI fired missile fly to a particular point if LOBL laser is lost mid flight?

LOAL/DIR assumes the currently active sight point (HMD, TADS, etc?) as the missile launch target and LOAL/LOHI assumes the ACQ point?

Is there any warning or indication  that one is inside the minimum practical range for shaped trajectories?

[AvroLanc]

56 minutes ago, Frederf said:

Thank you for this.

Does DIR/LO/HI change the flight profile for LOBL launches or are all LOBL launches the same flight profile regardless of trajectory setting? Does an e.g. LOBL/HI fired missile fly to a particular point if LOBL laser is lost mid flight?

LOAL/DIR assumes the currently active sight point (HMD, TADS, etc?) as the missile launch target and LOAL/LOHI assumes the ACQ point?

Is there any warning or indication  that one is inside the minimum practical range for shaped trajectories?

No, when the missile detects the correct laser code, before launch, it goes LOBL and follows the totally unique LOBL trajectory. The LOBL traj is unrelated to any of the 3 LOAL paths. 

The K missiles (SAL 2) allow the seeker to reacquire the laser spot but it doesn’t change or revert the trajectory or anything like that. 
SAL 1 seekers can’t reacquire the laser spot, if ED hopefully add those later to add variety.

Correct DIR uses TADS los and LO/HI use ACQ to tell it where to go.

You just need to remember the min ranges as best as possible and respect them. I think. 

[GrEaSeLiTeNiN]

On 3/31/2022 at 4:25 AM, AvroLanc said:

No, when the missile detects the correct laser code, before launch, it goes LOBL and follows the totally unique LOBL trajectory. The LOBL traj is unrelated to any of the 3 LOAL paths. 

The K missiles (SAL 2) allow the seeker to reacquire the laser spot but it doesn’t change or revert the trajectory or anything like that. 
SAL 1 seekers can’t reacquire the laser spot, if ED hopefully add those later to add variety.

Correct DIR uses TADS los and LO/HI use ACQ to tell it where to go.

You just need to remember the min ranges as best as possible and respect them. I think. 

Great info thanks. I was just doing some testing and trying to make sense of all this, then chanced upon this post and the OP. Some mental notes for myself (correct me if I'm wrong):

1.  LOBL happens as long as you lase first and it will have its own traj and disregard HI/LO/DIR.
2.  LOBL doesn't seem to need an ACQ. I mean I can select ACQ as FXD (looking at the sky) or as PHS (AI is just looking at the empty ground). As long as I can lase and track the target before launch (within parameters), the missile will hit the target. 
3. You will only see the HI/LO/DIR traj working if you fire without lasing first (LOAL). Yes, DIR can have a 'flatter' traj than LO but I guess it depends on the helo's altitude.
4. LOAL requires a stored target point (ACQ) as a fly-to point and the missile will fly over that point if lasing is too late. But I noticed I can hit a target way off to the left or right of the stored point so long as I lase the target early enough for the missile to change course. Correction: ACQ never guides the SAL hellfire in any manner but serves merely as a reference point for the pilot’s aim. The missile only ever flies to wherever the laser is pointed (within parameters).
    

Edited March 31, 2022 by GrEaSeLiTeNiN

[S. Low]

Thanks for the info

[GrEaSeLiTeNiN]

I see. So ACQ never guides the SAL hellfire in any manner but serves merely as a reference point for the pilot’s aim. The missile only ever flies to wherever the laser is pointed (within parameters).

[monkie]

This is a fantastic post since I had the idea as well that the constraints were needing to be met before firing the HF's and also that direct was only for LOBL, etc. Basically it doesnt matter what you have set up for ACQ, the HF's can be launched any direction you so desire. 

My favorite mission to create now is with the CTLD JTAC sitting on a hill and lazing for me as I sit 9km behind a hill nice and safe. 

Thanks for the post and clarifying exactly what the launch modes are really about.

[monkie]

So in the end the HF will never change their flight path from straight ahead UNLESS they can see the designation before launch?