Probably User Error, Possibly Bug, but All Bombs Fall Long in Direct or DT

[FMBluecher]

I picked up the F-4E on launch but haven't had much of a chance to play with it until now. Over the last few evenings I've been trying to learn unguided bombing in this Mostly Bomber, and I noticed something very weird: every single bomb I dropped fell long, and not by a small amount (about 500 feet).

To be clear: I'm not God's gift to piloting. I was expecting to be inaccurate, especially for someone who just started phlying the Phantom. But the weird thing is that the inaccuracy is consistent across every bomb type I have tried so far (CBU-52B, Mk83, and Mk82 LD). And it's consistent across modes: using the DT mode to designate the target, and using the Direct profile calculated in the Bomb Planner.

Now, while I'm new to the Phantom, I'm not new to unguided manual bombing. I've flown a fair bit in the F-5E, the Mirage F1, and the A-4E mod, and manual bombing in all of them was about as accurate as I was expecting: If I flew the profile on parameters, I was pretty accurate; if I flew the profile off parameters, I was pretty inaccurate, and in a predictable way. If I was fast, the bomb fell long, by an amount proportional to how much faster than the profile called for. But that's not what I was seeing in the Phantom: the bombs always fell ~500 feet long, even if I flew the profile nearly exactly. I would only miss by that much in the other aircraft I mentioned if I made extremely serious errors, like accidentally setting the wrong reticle depression by a large margin.

If I compensate for the issue, I get bang on target. In DT, if I designate the ground about 300-400 feet short of the target, the bombs land exactly where I'd expect--even when I'm not flying the profile properly. In Direct, if I reduce the reticle depression by about 50 mils from what the Bomb Planner calls for (as an example, the Bomb Planner said 140 mils; I set it to 90) and fly the profile well, again, I hit almost exactly where I'm aiming.

I am playing with the CPU: Lower Simulation Update Rate and CPU: Lower HB UI Refresh Rate options enabled. Might that be causing this? This seems weird, but I'm at a loss as to what's causing this. Also, for what it's worth, I did a DCS repair and that didn't fix things.

[Mike_CK]

Ok…I’ll start with the “is there gas in it?” Question. Did you pull up your bombing table first and set the appropriate bomb type? Even for DT, the computer needs to know what it’s tossing

[FMBluecher]

20 minutes ago, Mike_CK said:

Ok…I’ll start with the “is there gas in it?” Question. Did you pull up your bombing table first and set the appropriate bomb type? Even for DT, the computer needs to know what it’s tossing

Fair question! Yes, as far as I am aware, I did everything correctly using the bombing table, in both DT and Direct modes:

Set delivery mode, set bomb type, set airspeed, set dive angle, set target altitude, set release altitude.

And for DT, I did say "Tell Jester" and heard him verbally acknowledge my input. (Please, keep checking if I did anything dumb...I 100% would not rule anything out!)

[Zabuzard]

Would it be possible for you to record a quick attempt. Doesn't have to be pretty but it would help a lot to rule out any procedure issues such as for example pressing bomb button not exactly on target or flying ias instead of tas etc.

[FMBluecher]

6 hours ago, Zabuzard said:

Would it be possible for you to record a quick attempt. Doesn't have to be pretty but it would help a lot to rule out any procedure issues such as for example pressing bomb button not exactly on target or flying ias instead of tas etc.

Would you want a track, or me recording the in-cockpit footage? I assume the former but just wanted to check.

[Zabuzard]

Would you want a track, or me recording the in-cockpit footage? I assume the former but just wanted to check.

Tracks dont work with the HB UI yet (unless all interactions are done only through keyboard commands).
So a video would be needed here, unless you also give us a screenshot of what to enter into the bombing table for ur track to work while it replays :)

[BJ55]

16 hours ago, FMBluecher said:

And it's consistent across modes

Weird, I'm having wrong releases in any mode other than DT.

[FMBluecher]

The good news is that I think I figured out what I was doing wrong in DT! When I did a test run with DT, I nailed the target on my first attempt. (I think I had the aircraft out of trim on my previous attempts, so I kept fighting the controls and at the moment Jester locked on to the ground return, my reticle was oscillating far up from the target.)

The bad news is that Direct mode still seems wildly off. I've attached a quick track, as well as a screenshot of the bombing profile I set up. (I do realize that I failed to say "bomb on target: 2," but since I dropped in pairs anyway, I'm not sure this would have made a massive difference anyway.) I flew a pretty garbage run, to be frank, but, as far as I can tell, these were my mistakes:

1. slightly slow

2. slightly low

3. significantly too steep of a dive angle

But all of these should, according to my understanding, mean that I drop the bombs short--instead, they fall way over the target.

Manual Bombing Issue.trk

[Mike_CK]

My DT mode works a treat when I’m practicing. In “combat” though…it’s a train wreck. Which is a pretty good indication that I’m doing something dumb with the jet when digital bullets are flying. 

[Mike_CK]

Mine is going waaaay long at times. I think my issue may be that I’m too low/too shallow when I ask Jester to lock the area and when I hit the pickle; like it thinks I’m pointing at something further down range. Tried it at a 30degree dive and it was fine. Previously i had been about a 10

[Zabuzard]

On 10/5/2024 at 8:20 PM, FMBluecher said:

The good news is that I think I figured out what I was doing wrong in DT! When I did a test run with DT, I nailed the target on my first attempt. (I think I had the aircraft out of trim on my previous attempts, so I kept fighting the controls and at the moment Jester locked on to the ground return, my reticle was oscillating far up from the target.)

The bad news is that Direct mode still seems wildly off. I've attached a quick track, as well as a screenshot of the bombing profile I set up. (I do realize that I failed to say "bomb on target: 2," but since I dropped in pairs anyway, I'm not sure this would have made a massive difference anyway.) I flew a pretty garbage run, to be frank, but, as far as I can tell, these were my mistakes:

1. slightly slow

2. slightly low

3. significantly too steep of a dive angle

But all of these should, according to my understanding, mean that I drop the bombs short--instead, they fall way over the target.

Manual Bombing Issue.trk 1.18 MB · 0 downloads

Sorry, cant view the track. It requires the A-4 mod:

Could you retry making the track on a clean mission?

Note that the entered data is for the release-moment, which in DT differs from the dive-moment. In particular, the Dive Angle is the angle you have during your pullup maneuver when DT decides to release, not the angle you have during the dive. So if your angle at release-time differs heavily from 30°, perhaps thats the reason.

I can give you more info with a track I can work with, cheers

[FMBluecher]

On 10/21/2024 at 3:20 AM, Zabuzard said:

Sorry, cant view the track. It requires the A-4 mod:

 

Note that the entered data is for the release-moment, which in DT differs from the dive-moment. In particular, the Dive Angle is the angle you have during your pullup maneuver when DT decides to release, not the angle you have during the dive. So if your angle at release-time differs heavily from 30°, perhaps thats the reason.

I can give you more info with a track I can work with, cheers

Sorry about that! I don't have a lot of experience working with trackfiles, and didn't realize that would be an issue.

I think that was in fact the issue with the DT drop! I've been more successful with that since. Still working the Direct issue, and I won't have time to test this for a bit so I'll post again, with a new file that you can work with, if I encounter the issue again.

[FMBluecher]

OK, can confirm that the issue with DT was me not understanding what the Dive Angle was!

Still having issues with Direct, though, and hoping you can point me toward what I'm doing wrong:

1st Track: doing a low-drag run with Mk. 82s. Again, not a perfect run, but, according to Tacview, I released pretty darn near on-altitude. I was also pretty close to on-angle, and a bit slow--so I was surprised to have significantly overshot the target.

2nd Track: doing a high-drag run with Mk. 82SE. Delivered on-altitude according to Tacview and on-angle, while about 25 knots fast. I would expect to overshoot, but not by anywhere near as much as I did (especially with high-drag bombs).

Manual Bombing Issue 2.trkManual Bombing Issue.trk

[FMBluecher]

Can confirm user error for Direct as well!

Every other aircraft I learned to use Direct mode (or its equivalent) used IAS, not TAS, for their bombing tables, so I was accustomed to looking at the wrong airspeed indicator. That's why I was always dropping long (because KTAS is almost always higher than KIAS). When I started using the TAS indicator instead, I was much closer to what I'd expect.

[Zabuzard]

Can confirm user error for Direct as well!
Every other aircraft I learned to use Direct mode (or its equivalent) used IAS, not TAS, for their bombing tables, so I was accustomed to looking at the wrong airspeed indicator. That's why I was always dropping long (because KTAS is almost always higher than KIAS). When I started using the TAS indicator instead, I was much closer to what I'd expect.

Glad you were able to figure it out