Did real F-86F Sabre radar assisted gunsight "calculated" lead?

[avenger82]

Hi, I was under impression that F-86F radar and gyro assisted A-4 gunsight calculated lead - at least when smoothly following a target aircraft for at least a second in a constant turn (without skidding etc.). That's what I understood of F-86 manual.

 

But that's not how it seems to work in DCS. If I'm not close to a target I still need to manually estimate a little lead. It looks like it calculates where the bullets will go basing on range to a target and my aircraft's movement(at resulting angular speed of my reticle), but by the time the bullets reach it, the target will move a little.

 

This is what I believe is true: " The radar gunsight only computes the ballistic path of your rounds, not how far you have to aim ahead to hit the target. There's a very big difference. It cannot compute lead as it's not tracking the speed or heading of the target aircraft "

 

I found this :

 

" Aircraft such as the F-84, F-86 and F-100 still have a plain old gyroscopic gunsight. This gyroscopic gunsight is aided via a very simple ranging radar that does nothing but determine the distance between the defending aircraft and your own, and adjusts the gunsight accordingly. This radar ranging/gyro gunsight combination does not give lead. Instead, it simply shows you the ballistic trajectory, or where your bullets will go, depending on your range to target and the movement of your own aircraft, not the defending aircraft.

 

Please note that whatever solution a radar ranging gyroscopic gunsight gives you is not a lag indicator. Lag and lead indicators rely on the movement of the defending aircraft in order to calculate their solutions. The only thing calculated on the F-84, F-86 and F-100 is where your rounds will go according to your own current movement, not your enemy's. If your target starts maneuvering slightly upwards, the gyro gunsight in any of the aforementioned aircraft will not move a single millimeter until you move your aircraft to follow your target. It's not a lead calculating system as we know it, but a ballistic calculating system."

 

It's from Warthunder sub , but I think it's good explanation.

 

I asked this on Reddit, but after reading this I'm still not sure:

https://books.google.pl/books?id=gq88DwAAQBAJ&pg=PA63&lpg=PA63&dq=sabre+radar+lead+gunsight+OR+gun+skidding+OR+slipping&source=bl&ots=SAtqLNZ5i4&sig=ACfU3U3CpqyiF-Fr4GVqeEiXNqsTfrH9VA&hl=en&sa=X&ved=2ahUKEwiClOm30szpAhVypYsKHcCYD98Q6AEwAnoECCYQAQ#v=onepage&q=sabre%20radar%20lead%20gunsight%20OR%20gun%20skidding%20OR%20slipping&f=falsestill

 

It describes A-1 which I think was replaced by A-4 in F-86F.

https://imgur.com/T4dAKz8

 

https://imgur.com/dvq8avF

 

 

Wikipedia states such radar assisted systems calculated lead:

https://en.wikipedia.org/wiki/Radar_gunsight

 

 

DCS Manual on page 138 also states: "A-4 SI G H T. The A-4 automatic lead and ballistic computing sight "

 

And then on page 300:

 

9. After the radar target indicator light comes on (at a target range of

approximately 4,800 feet / 1,460 m), release the electrical caging button

to enable target tracking. As the caging button is released, the reticle will

drift down and then move back to the proper lead angle.

 

10. When you can track the target smoothly for approximately one second

without slipping or skidding, fire"

 

Here is the reddit post:

 

 

But again if I'm flying in a smooth constant turn , tracking a target for at least a second , shouldn't the piper point to where the target will be by the time the bullets will end up there?

Edited May 24, 2020 by avenger82
Minor edits

[71st_AH Rob]

The sight does calculate lead. You need to set the manual range to max setting for the sight to calculate the range correctly using the radar range value.

 

 

 

There was a small problem with the lead calculation, I believe it is due to bullet drop - the muzzle velocity of the rounds that the sight is calibrated for a higher velocity round, however there a few different variables that could cause the problem.

 

 

 

The A-4 is a WWII gyroscopic site that can use the AN/AGP-30 RADAR to supply the range instead of entering it manually.

[AeriaGloria]

Track target as same G from behind with pipper for one second(or settling time), or for a snap shot fire one bullet TOF Before pipper is on target. You could say it’s telling you where your bullets will be at target range irrespective of the target maneuvering or position

[avenger82]

The sight does calculate lead. You need to set the manual range to max setting for the sight to calculate the range correctly using the radar range value.

 

 

 

There was a small problem with the lead calculation, I believe it is due to bullet drop - the muzzle velocity of the rounds that the sight is calibrated for a higher velocity round, however there a few different variables that could cause the problem.

 

 

 

The A-4 is a WWII gyroscopic site that can use the AN/AGP-30 RADAR to supply the range instead of entering it manually.

 

I’m aware manual range needs to be left to max and definitely have radar range working. I’m pretty sure it doesn’t calculate lead based on target movement, angular speed etc. , but rather tells you where bullets will end up based on the G the attacker is pulling. From my experience in DCS Sabre I still have to put small lead before a turning target. However I’m really struggling to smoothly and accurately follow a aircraft in a medium to high G turn . But even in training mission with very slow constant turn I have to put some small lead when firing from decent distance. I don’t think it’s the bullet drop you mentioned, but I may be wrong.

[Kang]

I’m pretty sure it doesn’t calculate lead based on target movement, angular speed etc. , but rather tells you where bullets will end up based on the G the attacker is pulling.

That is exactly what it's doing, but at the end of the day, that's how it calculates the lead for you.

 

Mind you it's pretty much a mechanical device, there is no microcontrollers to do any actual calculations and there certainly isn't any way for the device to have a finely resolved picture of angular movement to even start those.

[streakeagle]

The real life sight was problematic. Some pilots swore by it, others left the gyro off because of reliability issues and trust in their own ability to judge lead.

 

I find the DCS P-51D sight to me more accurate. I don't know why. The radar ranging should make it at least equal if not better.

[avenger82]

The real life sight was problematic. Some pilots swore by it, others left the gyro off because of reliability issues and trust in their own ability to judge lead.

 

I find the DCS P-51D sight to me more accurate. I don't know why. The radar ranging should make it at least equal if not better.

 

Yes, I've read that some pilots didn't like how it works had it turned off (caged gyro).

I don't have P-51D, but that's also my understanding - it should be very similar except you need manually adjust range.

[Kang]

I take it that given the much higher speeds and often longer firing ranges the whole system is just a little more prone to error. A slight bump on the stick, a little change in angle and it's off again. Getting the automatic ranging should take one task off the pilot's back, as you could now fire from anywhere within the range, but it also meant you wouldn't have that one engagement range you would know what deflection to use at.

[avenger82]

I take it that given the much higher speeds and often longer firing ranges the whole system is just a little more prone to error. A slight bump on the stick, a little change in angle and it's off again. Getting the automatic ranging should take one task off the pilot's back, as you could now fire from anywhere within the range, but it also meant you wouldn't have that one engagement range you would know what deflection to use at.

I don't know how higher speeds could affect it. As long as closure speed is low (and you don't pull huge G) it shouldn't matter. I've read somewhere that it works (best?) up to 3G, but I think it wasn't in official manual.

Anyway I still think something is wrong with lead calculation in DCS F-86F. But I know it wasn't perfect IRL either.

[Kang]

My thinking was that for a given aspect angle a higher speed leads to a higher overall deflection, thus any error makes the pipper with higher amplitude. As in, a little unwanted change in G makes it wander much more than it does at lower speeds. But then, what do I know.

[avenger82]

My thinking was that for a given aspect angle a higher speed leads to a higher overall deflection, thus any error makes the pipper with higher amplitude. As in, a little unwanted change in G makes it wander much more than it does at lower speeds. But then, what do I know.

If Gs would be the same as at lower speeds, then pipper should wander the same. Of course at higher speeds (which are more likely with jets) you get higher Gs so it will affect accuracy.

Pipper wandering due to G changes is one thing, but having to manually put a lead even when smoothly tracking a target is another.

Maybe my Gs are not that constant as I would think:)

It’s interesting few people complain about the gunsight in DCS. Maybe they are not sure how it’s supposed to work (apparently neither I am), and just cage it.

But I would like it to work as close to real as possible, even if it means it’s indeed not useful in many cases.

Edited May 28, 2020 by avenger82

[Kev2go]

The sight does calculate lead. You need to set the manual range to max setting for the sight to calculate the range correctly using the radar range value.

 

 

 

There was a small problem with the lead calculation, I believe it is due to bullet drop - the muzzle velocity of the rounds that the sight is calibrated for a higher velocity round, however there a few different variables that could cause the problem.

 

 

 

The A-4 is a WWII gyroscopic site that can use the AN/AGP-30 RADAR to supply the range instead of entering it manually.

 

The A4 isn' t from ww2. Its korean era tec. The A4 replaced the earlier A1CM gunsight ( which was more problematic) from F86A and F86E's

[71st_AH Rob]

The A4 isn' t from ww2. Its korean era tec. The A4 replaced the earlier A1CM gunsight ( which was more problematic) from F86A and F86E's

 

Of course I know the A4 isn't from WWII.

Edited May 31, 2020 by 71st_AH Rob

[Bob1943]

I flew the F-100D from 1969 to 1971, including a combat tour in Vietnam. Our role in Vietnam was air to ground, I never engaged a Mig while I was there. However, I did fly air-to-air gunnery training missions while going through the F-100 training program at Luke AFB. When firing on the airborne drogue targets, you had to have the pipper on the target to get a hit. So, yes, the sight pipper is predicting bullet impact, based on range, ammo ballistics, and G-load.

 

I have attached 2 pages from my F-100 Flight Manual, which specifically discuss the operation of the A-4 sight.

[Squiffy]

Awesome Bob! Thanks so much and really glad you are here! The cannons on the 100 must have been something!

[avenger82]

I flew the F-100D from 1969 to 1971, including a combat tour in Vietnam. Our role in Vietnam was air to ground, I never engaged a Mig while I was there. However, I did fly air-to-air gunnery training missions while going through the F-100 training program at Luke AFB. When firing on the airborne drogue targets, you had to have the pipper on the target to get a hit. So, yes, the sight pipper is predicting bullet impact, based on range, ammo ballistics, and G-load.

 

I have attached 2 pages from my F-100 Flight Manual, which specifically discuss the operation of the A-4 sight.

Thanks for the input! So this confirms what I recently read - Even late WW II warbirds versions of Spitfire or Mustang etc. had gunsights that “calculated” lead (based on range, attacker’s G, bullet drop etc.) Perhaps even altitude (so estimated air density for bullets drag) was taken into account. Of course range had to be adjusted manually.

Im not sure if it was working accurately at high Gs. It’s a well known fact some real F-86 pilots didn’t like the gunsight and left it caged during combat. Especially earlier gunsight versions than in f-86F model, were not that reliable.

 

But Im afraid in DCS F-86F it’s not implemented correctly - at least It really seems to me you have to to put some lead to hit a plane that has some angular speed relatively to the attacker.

But maybe it’s just me because I’m struggling to smoothly track a target for a full second and often don’t use rudder to avoid slipping, especially when chasing in a tight turn.

 

Have you tried F-86 in DCS? If yes, what do you think?

Edited June 4, 2020 by avenger82

[Squiffy]

Yes! Bob, please let us know. I'ts pretty much all I fly and I just am not ready to share my skill in mulitplayer. The Torque and PFactor of the props also drive me up the wall. The slop in my worn out Cougar make slow flight and fine adjustments pretty silly.

 

For deflection shooting in the Sabre and Mustang, I have the 4 way hat switch on my throttle set on the y axis for seat position. I also have TrackIR and use padlock. It helps a lot to click in a couple notched of seat height up so you can see down over the nose some more. Usually enough that the pipper is not visible all the time. I track my tracers more and stay with short bursts to see the bullet arc. This way, you can "hose" the bandit a lot easier. When slow and close like at the top of a loop or vertical, the pipper makes more sense, but at higher g and tighter turns, use your tracers and hose them with what you see out in front.

[AeriaGloria]

You speak of giving lead when there is angular motion of target, that’s esssentially a snap shot, where you do need to fire 1x bullet TOF before target is on the pipper, so that once the bullet gets there(pipper = bullets at target range) the target is in the pipper

[Schmidtfire]

Issue is that the bullets land below the pipper.

If ED adjusts the default position of reticle a bit lower on the glass we might get rid of the issues.

In my opinion the current sight is also too fast and nervous, and should instead float around more slow and steady. But Bob1943 probably knows more about that.

[avenger82]

You speak of giving lead when there is angular motion of target, that’s esssentially a snap shot, where you do need to fire 1x bullet TOF before target is on the pipper, so that once the bullet gets there(pipper = bullets at target range) the target is in the pipper

 

 

Yeah when target is turning and I'm trying to follow/track him with the pipper it looks like I still need to give some lead for the bullets to have time to reach the calculated range.

In close ranges it works pretty good of course. Also the gunsight in DCS certainly responds to G load, I mean it's most evident when you start pulling a stick (the reticle moves down) etc.

And I agree with @Schmidtfire seems to react too fast and "nervous".

Edited June 5, 2020 by avenger82
added G load behavior description

[Buzzles]

Not that it helps, but this current behaviour was added in patch a little while after launch from what I remember.

 

At launch and a little while after, I recall the having the pipper on target working absolutely fine.

[avenger82]

Not that it helps, but this current behaviour was added in patch a little while after launch from what I remember.

 

At launch and a little while after, I recall the having the pipper on target working absolutely fine.

 

Interesting so it probably was on purpose. They might have thought it's working too good - too easy = not realistic. Just a speculation. So by trying to fix it seems to me they made it worse.

[Buzzles]

Interesting so it probably was on purpose. They might have thought it's working too good - too easy = not realistic. Just a speculation. So by trying to fix it seems to me they made it worse.

 

 

So, I knew there were prev threads about it, this is from June 2016

https://forums.eagle.ru/showthread.php?t=167980

 

Turns out I posted in it at the time saying it'd changed, which was backed up by a couple of others like BSS Sniper.

 

There's a few other threads at the time too, like this bug report:

https://forums.eagle.ru/showthread.php?t=162596

 

 

Now, fun times depend on if the sight's wrong, or if the sight's correct but bullet muzzle velocity is too slow as argued in this long running thread:

https://forums.eagle.ru/showthread.php?t=165936

[avenger82]

Thanks, that’s a good read, but at the same time frustrating how difficult is to convince ED to fix something.

So was the lead computing issue ever acknowledged by ED or Belsimtek?

It’s strange it’s still not fixed. Doesn’t anyone care if gun in F-86F is working correctly or they just gave up and just keep it caged? I’ve read in Mustang the lead computation is working fine.

 

Was too low bullet velocity also not fixed? Then it contributes too, but I think reticle movement based on G load is still unrealistic and even at 900km/h it would not give enough lead.

 

Edit: I’ll try edit/mod .lua files to increase the velocity and test if it helps.

Edited June 6, 2020 by avenger82

[Alphazulu]

I can tell you that the A4 radar sight does work just fine. You just have use it within it's limits, practice with it and the M3 muzzle velocity does have a lot to do with it. I have shot down more Migs that I can count using it. Here is the thing about the M3 guns in DCS, they overheat and warp extremely fast. So if you have fired the guns in several bursts one after the other you will see the tracers starts to go a bit wild. Also if you get in an F2 view when this is happening you will see that the tracers stop flying out in a predictable manner and start falling out of the sky very early on, almost right after they leave the guns. In this case, the radar gunsight is never going to work. It does not calculate for the degraded flight path of the rounds at all once the barrels start to warp.

I made a mod that removes the gun heating and warping and if you run this mod, the radar gunsight works like a charm almost every time. However if you don't run the mod and are sticking on the Migs 6 constantly shooting the radar gunsight stops working after a couple consecutive bursts. I never stick to a Mig-15s 6 anyways as the bis can out tur the F-86-F35 in most cases. I always maintain my energy, shoot and then go vertical as they try to slow down, loop and come back around for another slashing attack. This also greatly helps in keeping the guns from overheating and warping.

 

Other tips that I cab add from experience is, one, try to put the piper far up on the target mig. almost on it's nose. Two, make sure you have the range knob for the radar slaved to your throttle, it works much better if it is not looking to far out past the enemy plane. Adjust it and your lock light will get more stable. Third make sure it is set to "High" foor the deflection as migs always turn fast. This setting is on the weapons panel.