AUTO bomb steering line

After reviewing some HUD tapes I think the plot is a bit thicker than "the ASL must bisect the TD".

 

The McDonnell Douglas/Boeing aircraft share a lot of symbology similarities, but I found two videos showing AUTO drops (

and one in a Harrier GR7).

 

In both situations, the ASL is proportionally further in the opposite direction of the TD as the VV is relative to the ASL. So if your VV is to the right of the ASL, in calm winds the ASL should appear left of the TD.

 

Apparently high crosswinds can also affect the alignment of the ASL and the TD.

 

I'm willing to bet both the Harrier and Hornet ASLs are broken in different ways right now:

 

- Hornet's ASL shouldn't always by aligned perfectly on the TD.

- Harrier's ASL should always be on the side of the VV you need to be turning to align yourself with the target.

Yep, that is wind correction, especially the HUD from the Harrier. The ASL shows the wind corrected release point. The issue is that currently the ASL moves left and right depending on the plane's bank angle. Thus we have the VV left of the designated Target and the ASL further left from the VV if you bank the plane. This is plain wrong, as your pictures show the ASL should be anywhere to the opposite side of the target in reference to the VV to indicate the direction you need to steer to align with the target/release point. Currently it leads you away(!) from the release point as soon as you bank the plane.

wind correction, or high bank angles/ momentary incorrect inputs from the radar altimeter, drift etc. may position the ASL to the side of the target when calculating the release point. The calculation is a continuous process and is not instantaneous, I bet.

The Harrier HUD footage does not appear to be solely wind correction, as the ASL moves in relation to the TD in concert with the VV's movement/bank relative the ASL. This is most apparent in the pop where as the VV drifts right of the ASL in a slight bank, the ASL also drifts left of the TD.

 

And in the Hornet footage, the distance from the ASL to the TD gets narrower as the distance between the VV and the ASL gets narrower. You can barely make it out on the roll to wings level before the TD exits the screen.

 

ASL descriptions in the manual make no mention of always or necessarily passing through the TD, and figures shown in the TACMAN illustrate conflicting symbology or behavior inconsistent with HUD footage and other training documents that show ASLs that aren't aligned on the TD for various reasons.

 

I think this is one case where the illustrations can only do so much, but I agree that the ASL steering behavior is still off.

Edited January 22, 2019 by ChickenSim

I've noticed that the ASL is actually adjusting heading as one banks the aircraft. It's visible in this video -

 

That certainly shouldn't be occurring. And as Chicken mentioned the manuals are not explicit about the ASL passing through the TD. We need some more HUD footage of AUTO bombings in Harrier II's to really understand what's going on, TACMAN's are getting us nowhere.

I've noticed that the ASL is actually adjusting heading as one banks the aircraft. It's visible in this video -

 

That certainly shouldn't be occurring. And as Chicken mentioned the manuals are not explicit about the ASL passing through the TD. We need some more HUD footage of AUTO bombings in Harrier II's to really understand what's going on, TACMAN's are getting us nowhere.

The major issue is the banking causes the ASL to swing violently. The ASL (Azimuth STEERING Line) should indicate the course correction TOWARDS the release point/target.

I hope we can agree so far. See the Screenshot I made and marked clearly how the ASL indicates to fly AWAY from the target when banking.

Now, if the ASL should disect with the target indicator likely depends if there is crosswind, the aircraft is holding it's bank or just maneuvered and things like slip ( uncoordinated turn), height calculation input, and what not... I simple refered to my test where there is no wind and I really have no issue with the ASL adjusting and thus not disecting through the target.

My problem is the ASL violently swinging with the bank angle even if the plane flys directly towards the target. This swinging with bank is not correct.

Hello,

I had a look to the greek f-16 TAC manual.

The Asl does not go through the target designator on the illustrations of ccrp mode, and it is reminded tha asl steers to the release point, ( not the target)

And it explains for dive toss that « immediately after designation, the asl will be displaced from the fpm by an amount that reflects the steering error due to wind. »

And The fpm must line up with the asl at release.

 

So this seems to tell us that:

Azimuth steering line has to be vertical ( it’s azimuth only)

Asl is wind drift compensated in order to steer the release point

Therefore does not necessarily go through the target designator , by an amount that reflects the steering error due to drift (no wind’ no drift’ then asl goes through target designator

NB: the determination of the release point has to account for wind, ground speed and altitude, so , I suppose, it has to move with current aircraft GS and altitude.

Hello,

I had a look to the greek f-16 TAC manual.

The Asl does not go through the target designator on the illustrations of ccrp mode, and it is reminded tha asl steers to the release point, ( not the target)

And it explains for dive toss that « immediately after designation, the asl will be displaced from the fpm by an amount that reflects the steering error due to wind. »

And The fpm must line up with the asl at release.

 

So this seems to tell us that:

Azimuth steering line has to be vertical ( it’s azimuth only)

Asl is wind drift compensated in order to steer the release point

Therefore does not necessarily go through the target designator , by an amount that reflects the steering error due to drift (no wind’ no drift’ then asl goes through target designator

NB: the determination of the release point has to account for wind, ground speed and altitude, so , I suppose, it has to move with current aircraft GS and altitude.

So the F-16 TAC manual neither says anything about the ASL moving in the opposite direction of the target depending on the bank angle (and only on the bank angle) like it is currently, correct?

Got a reminder from Capt_Cheezypoof (Harrier pilot) in the S&A discord that the ASL is only valid in wings-level unaccelerated flight. This is likely the explanation for the apparent swaying seen in both HUD videos in both extreme and shallow banks, but I agree that the direction it sways is incorrect at the moment.

Making ASL sway in the right direction would be a good start. Should be quite easy to implement.

Maybe also make it’s movement a bit slower and less sensitive?

 

Since CCIP also has it’s share of issues, I would not trust that Razbam got the ASL correct the first time. It clearly needs work, just hope that they fix it as bombing is one of the main functions of the Harrier. I can deal with broken Sidearms, no hotspot detection, unfinished DMT etc. But not something as basic as proper symbology during CCIP/CCRP bombruns.

Shagrat:

There is no mention of bank angle or acceleration in the F-16 doc: ASL gives azimuth to the release point and you have to put your flight path marker on it. (easy to say not to implement)

 

It does not move with acceleration or banking , contrary to the ccip line (which indeed goes right when you bank left, might be a clue to the confusion, if Razbam reuses parts of the code)

I still don't think we can use other aircraft for comparison, thing tend to be different even on different models of the same aircraft. Additionally there are many things youtube type video don't show. Like specifics of the aircraft, setting the pilot did etc.

For example, this is suppose to be Canadian F/A-18 but I have not way of verifying that. The editor could have added stock footage. But you can see is in a dive, using auto delivery, ASL is not coming from the target box, and it moves with aircraft bank.

[ATTACH]202817[/ATTACH]

There more example on the video

 

Here is block 40, from desert storm 1 in a dive, bomb fall line is not coming form the target and it moves with aircraft bank.

[ATTACH]202822[/ATTACH]

But the video is so low quality, is hard to tell anything of value.

 

This one they are using CCIP, but looks like they are diving on target while AAA fire at them, which I guess they are not suppose to do

 

Is any of this accurate? I do not know. Does it relate to the USMC AV-8B Night attack in DCS? I don know. Not only do we need HUD video of the night attack, we need to see with target out the HUD since that is what you guys want too change the most IIUC

Got a reminder from Capt_Cheezypoof (Harrier pilot) in the S&A discord that the ASL is only valid in wings-level unaccelerated flight. This is likely the explanation for the apparent swaying seen in both HUD videos in both extreme and shallow banks, but I agree that the direction it sways is incorrect at the moment.

That's what I am trying to get across. In a no wind situation, flying straight towards the target, the ASL currently swings proportional to the bank angle in the direction you are starting to fly away from the target! It needs to either stay at the Target or if it is recalculating the release point and thus moving it should still be on the side towards the target from the velocity vector...

As it is currently it does not work as a STEERING line as it leads you away from the actual release point if you start banking.

I still don't think we can use other aircraft for comparison, thing tend to be different even on different models of the same aircraft. Additionally there are many things youtube type video don't show. Like specifics of the aircraft, setting the pilot did etc.

For example, this is suppose to be Canadian F/A-18 but I have not way of verifying that. The editor could have added stock footage. But you can see is in a dive, using auto delivery, ASL is not coming from the target box, and it moves with aircraft bank.

[ATTACH]202817[/ATTACH]

There more example on the video

 

Here is block 40, from desert storm 1 in a dive, bomb fall line is not coming form the target and it moves with aircraft bank.

[ATTACH]202822[/ATTACH]

But the video is so low quality, is hard to tell anything of value.

 

This one they are using CCIP, but looks like they are diving on target while AAA fire at them, which I guess they are not suppose to do

 

Is any of this accurate? I do not know. Does it relate to the USMC AV-8B Night attack in DCS? I don know. Not only do we need HUD video of the night attack, we need to see with target out the HUD since that is what you guys want too change the most IIUC

The point where the comparison does a pretty good job is, when you compare standard systems based on how they fulfil their purpose.

Take a car, the indicator lever will work the same and is comparable. The steering wheel will use clockwise-counterclockwise to steer left/right in a predictable manner. If it would be reversed in your car you don't need a video proof.

The current ASL does not fulfil its purpose as an Azimuth STEERING Line.

For that purpose it needs to show you the direction to where you need to bank to get to the release point. As of now it indicates a bank further away from the target as soon as you start to correct your flight path. What you do in your screenshots is basically flying only with the target designator and ignoring the ASL until you are already aligned with the target and wings level. But then you don't need the ASL any more.

Yep, I think we are on the same page shagrat. I'm agreeing with you and just clarifying that there should be some error outside level flight. I think we are all saying the same thing now.

Making ASL sway in the right direction would be a good start. Should be quite easy to implement.

Maybe also make it’s movement a bit slower and less sensitive?

 

Since CCIP also has it’s share of issues, I would not trust that Razbam got the ASL correct the first time. It clearly needs work, just hope that they fix it as bombing is one of the main functions of the Harrier. I can deal with broken Sidearms, no hotspot detection, unfinished DMT etc. But not something as basic as proper symbology during CCIP/CCRP bombruns.

^this

I understand this is a bit of a hot topic and it was brought to my attention by a participating member in the conversation. We ("Speed & Angels " and affiliated pilots) try not to actively seek out controversial issues but if the powers that be would like to contact us on our discord, im sure the harrier pilots would be happy to answer questions where they can. The link is below.

 

Hope this helps:)

I understand this is a bit of a hot topic and it was brought to my attention by a participating member in the conversation. We ("Speed & Angels " and affiliated pilots) try not to actively seek out controversial issues but if the powers that be would like to contact us on our discord, im sure the harrier pilots would be happy to answer questions where they can. The link is below.

 

Hope this helps:)

 

Thanks for reaching out Lex, I hope Razbam take you up on this as this seriously needs to be fixed. I was slinging some GBUs tonight and it was a painful experience.

Found an image of AUTO bombing while banking.

Found an image of AUTO bombing while banking.

...we had an interesting discussion over at Speed & Angels discord. The general consensus is the ASL will correct for crosswind and or re-adjust for aircraft movement, but not depending on bank angle, as it does now.

 

An excellent video posted demonstrates the core principles from the original system in the A-7... and though the symbology is very 70ies it perfectly shows how the concept works (see from 4:20 and 9:48)

So who will forward this to Zeus67/Razbam? First step is to get this bug aknowledged.

NVM, sort of wrong, check my page length post below.

Edited January 31, 2019 by Harlikwin
I was wrong.

So after a quick look at the Tac manual. Wow lots of functionality missing. Mainly centered around how to find/input target alt, which is critical. The pre programed mode is totally absent, and i think we get the arcade mode of baro-alt mode, not radar or gps. Also no way of inputing wind spd.

 

I´d like to read up on this.

Can you specify the TAC Manual/ Pages?

I´d like to read up on this.

Can you specify the TAC Manual/ Pages?

 

I will PM you the document because of rule 1.16. Anyone else interested in the TAC manual just PM me.

I will PM you the document because of rule 1.16. Anyone else interested in the TAC manual just PM me.

 

Thanks much for that!

 

I have the manuals, just wanted a pointer on where to find the stuff Harlikwin is referring to.

Thanks much for that!

 

I have the manuals, just wanted a pointer on where to find the stuff Harlikwin is referring to.

Chapter 2 in general. Chapter 2.4 ff for Designation, Delivery modes etc. around page 530...

Thanks much for that!

 

I have the manuals, just wanted a pointer on where to find the stuff Harlikwin is referring to.

 

Ok, wow didn't want this to turn into a dissertation but it seems like it has. And boy did I learn alot by RTFM :).

 

And if you are of the TLDR variety I think the canted auto bomb line is actually correct. Though you shouldn't be bombing at 45 degree bank angle anyway.

 

Non TLDR version:

 

NWP 3-22.5-AV8B, Vol. I

 

Basically Chapter 2 is theory, and how the ARBS actually works to solve the height above target issue (basically solves for slant range using angles and maths). It also talks about how Down range travel (DRT) is affected by the designation point location (as long as designated altitude = target alt). Figure 2-14 describes this. Its also notable that ARBS deals with target motion by calculating it as a wind component, and also aircraft motion to calculate wind (which I didn't know) but makes sense. Though it also talks about using "range winds" vs ARBS crosswind values (preferred). So I think its possible to enter winds manually which may not be modeled, but is not the prefered method. Basically the ARBS is "magic" and I "think" parts of it are reasonably well modeled.

 

Alot of the "theory" is in section 2.2.3.2 (solving the bombing triangle, or figuring out plane height above target), One of the inputs the night attack models really relies on for accurate bombing is that it has to know the planes altitude above target (easy if using ARBS, less accurate with radar alt or baro alt or gps alt). BUT for accurate bombing you must know the height above target. You "can assume" the ground is flat and use radar alt or GPS or Baro alt, but this isn't always the case and those modes are less accurate as a result.

 

One of the key advantages of using the way-point/ins bombing mode is you can pre-program the target position/altitude as its typically known and this gives you good precision for "strike" roles (hitting a bridge, or building or whatever) and you don't ever even have to see the target. (And I think this is in game now?) You can also program offsets, which I don't think is in game?

 

Using the DMT/ARBS, its a bit less accurate since it can compute the target alt but it uses aircraft spd and angle rate to target, but what you'd have to use for CAS and its still pretty accurate unless you have a big difference between where the target actually is and system "thinks" it is.

 

Im not sure to what extent razbam is "modeling" most of these details i.e. if the various inputs the ARBS is using are actually used for the computation (with their own system error rates) or if its just perfect target data fed into a more generic DCS bomb drop calculation.

 

 

Talking about different ways to select targets in 2.4

(some of this is in the module some of its maybe not, notably WOF or TOO functionality but I haven't tried it) as well as creating targets as waypoint offsets.

 

Section 2.5 talks about delivery modes.

Basically we have

 

AGM which sort-of works with its various bugs for missiles.

 

AUTO (currently maybe or maybe not messed up symbology and the topic of this thread)

 

LOFT (a submode of AUTO, that is entirely missing AFAIK)

 

CCIP (working? maybe not entirely correctly (not sure whats wrong with it))

 

DSL (missing entirely? IDK, never used it)

 

Both the AUTO and CCIP modes do appear to be missing their various altitude sub modes ® (B) (G) (radar/baro/gps), though the ARBS is the most accurate mode anyway and uses either CCIP or AUTO as the symbology. If you are using something other than the ARBS else as your altitude source you get R/Baut symbology on the HUD. (Figure 2-51)

 

To add some further clarification/confusion to the discussion if you look at Figure 2-52 in AUTO mode, it does have the ASL "canted" and not straight up and down. But if you look at figure 2-58 its straight up/down. And then if you look at figure 2-59 its "canted" again because the plane is banking, and is perpendicular to the horizon indicator.

 

It also states that the "ASL denotes steering to target instead of steering to release point in ALL sensor notes.) Also its stated in 2.5.1 that the ASL is limited in the lateral direction to the HUD total field of view (TFOV) and is always oriented perpendicular to the horizon (roll stabilized)"

 

So, I think the canted line is actually correct and not a bug.

 

at 7:10 is the video, the line does seem to move and is canted a bit. (This is good vid to watch)

 

 

Interestingly in that Video they claim you can use the TV tracker for AA target ID...

Edited January 31, 2019 by Harlikwin