K-14A

[waylander]

is this modelled in the current version? i couldnt get the symbology to show up like the image shows before the training

[cichlidfan]

is this modelled in the current version? i couldnt get the symbology to show up like the image shows before the training

 

Did you turn on the Gyro Motor Power?

Edited May 2, 2012 by cichlidfan

[flightace37]

Yep. Make sure guns are armed on the front switch panel and turn on gyro power on the gunsight panel on the upper left of the dash (switch pointed down and right). You can then use the rotary there to cycle between the different sight modes. The wingspan and range dials work, but range seems to be pretty limited at the moment unless I'm missing some kind of override to allow it to go beyond about 250 yards. There are graduations for further distances, but I usually set it around 150 anyway, and I'm not sure what the modeled convergence is.

Edited May 2, 2012 by flightace37

[Blaze]

Sure is modelled! Make sure the gun system is armed (switch is located on center panel, just above the Fuel Shutoff Valve), and then gyro power on and select one of the 3 gunsight modes. Also note, you can click and drag the adjustment knob and bar on the gunsight to adjust the size of the reticle. :)

[159th_Viper]

Also note, you can click and drag the adjustment knob and bar on the gunsight to adjust the size of the reticle. :)

 

Yes, be sure to adjust for range as well as wingspan.

[waylander]

i have been playing the aerial gunnery - gyro sight training so the plane is set up correctly, enter 37ft wingspan like it tells me, i never get the piper like in this image.

 

imo it would be nice if those training missions had a third plane that flew a circuit straight and level just to get used to setting the range correctly, labels are in nm and the range dial is in feet and the planes you have to practice against fly more aggressively the closer you get

 

 

Edited May 2, 2012 by waylander

[159th_Viper]

Toggle your Gyro Selector Switch to Gyro.

[waylander]

its on gyro when the training starts, maybe i wasnt clear i get the aiming reticule i never get the little piper that shows how to lead the target

[flightace37]

You mean the little bore sight + mark? That doesn't show up in pure gyro mode for me either. You can switch to fixed+gyro mode to overlay the full fixed sight and use that to help you learn expected lead angles.

 

As far as aiming with the K-14A is concerned, you just place the pipper on the target without any regard for where the fixed sight is pointed. Place the dot on the target, adjust the range until the ring is set to apparent wingspan, hold for a short time to let the sight recompute, then pull the trigger.

[IvanK]

You mean the little bore sight + mark? That doesn't show up in pure gyro mode for me either. You can switch to fixed+gyro mode to overlay the full fixed sight and use that to help you learn expected lead angles.

 

As far as aiming with the K-14A is concerned, you just place the pipper on the target without any regard for where the fixed sight is pointed. Place the dot on the target, adjust the range until the ring is set to apparent wingspan, hold for a short time to let the sight recompute, then pull the trigger.

 

Use the Gyro + Fixed reticle and the then the blanking lever on the left hand side of the gun sight head. Having a fixed refrence (think of it as the Gun Bore line) is a great aid.

 

Basic LCOSS Gyro gunsight handling is an art. The real world technique is below. As to tracking technique the fixed reference is most important. GYro sights are historical devices and not real time. So simply trying to drive the Gyro reticle on its own is like trying to change the past :). Real world technique is to place a fixed reference (+) ahead of the target on its plane of motion (The imaginary line between the + and the reticle .... this is known as "the line".... its even indicated on the F15 LCOS system). Then to get the reticle on the target make small smooth changes to the + position keeping the gyro pipper in your peripheral vision.... dont concentrate on the Gyro reticle. Once the gyro reticle is on the target track for a second or so (it has around 1 sec settling time before its accurate ... this is the historical part) then fire.

 

At the longer ranges sight handling is easier if you range the sight down, this provides a stiffer sight and reduces over controlling. Then as you estimate approaching firing range accurately range the target (span his wings with the adjustable reticle size) and fine tune the tracking.

 

:)

[IvanK]

Here is a burst I wrote for guys in my IL2 squad on K14 operation and pilot technique. It pretty much applies to all basic Gyro gunsights. In IL2 you couldn't blank the fixed reticle, other than that its pretty much the same as in DCS P51.

 

 

 

 

[flightace37]

Nice article(s), Ivan. Re-reading my post a few hours later (and then reading yours) made me realize just how much I left out. From waylander's language, I thought he was treating the MFBL as a "put the pipper here to hit the target" indicator and my concern was just to correct that notion. I did a very poor job of that with the wording I chose.

 

You absolutely have to account for plane of motion when lining up a shot. Just placing the pipper on the target without regard for maneuvering doesn't give you a firing solution whatsoever. The fact is, if you're not in the target's plane of motion, that pipper isn't going to stay put during the 1.2x TOF time delay.

 

Thanks for the tip about the blanking lever. I'll put that to use the next time I'm up to shoot something. I do have one thing that I'd like clarified.

 

Consider that you're in the target's plane of motion with high TCA, moving towards an overshoot while pulling lead for a gun shot. You could keep the pipper on the target by pulling more and more G while reducing the range setting to match target wingspan as you close the distance (up to a point).

 

Now, the sight has a settling time. Given that conditions are rapidly changing, does the settling time invalidate the displayed firing solution? I know you can certainly add some kentucky windage, but I'm talking strictly about the computed solution.

Edited May 3, 2012 by flightace37

[IvanK]

"Now, the sight has a settling time. Given that conditions are rapidly changing, does the settling time invalidate the displayed firing solution? I know you can certainly add some kentucky windage, but I'm talking strictly about the computed solution."

 

IRL strictly speaking yes, its the nature of any Historical sight. Thats why its so important to have smooth steady tracking with good (slow closure) as that mitigates the latent lag in the system. Given the settling time is actually a factor of bullet time of flight, the settling time also goes down as range reduces. A perfect solution is really only achieved if.

 

1. Range is constant.

2. G/Turn rate is constant

3. Ranging correct

4. Pipper on for the settling time for the required range.

 

(noting that Gravity Drop is applied in the plane of motion not earth vertical, and trajectory shift is not actually constant but a fudge factor is built into the lead solution... so strictly speaking the "Perfect" solution is always going to be an "approximate" solution. Pattern harmonisation of the guns and dispersion helps in this area.) A final point the "solution" is only correct for conditions of 1 settling time ago.... i.e. in the past.

Edited May 3, 2012 by IvanK

[Maximus_G]

I'm trying to figure it out, the GGS Mk.II and its clones, USN Mk.18 and K-14: what type of LCOS sight it was? Historical (real-time) or predictor (director)? Is there any reference for this subject?

[IvanK]

Straight out Historical (which by definition is not real time :) sight. I have an RAF doc "Weapons notes for flying personnel Fixed gun sighting Air Phamplet No 252" that describes its operation clearly. They are basic first generation Gyro sights. I have IRL used the French version of the British GGS II the CFS97K other than an ability to input radar range (rather than stadimetric) its operation was essentially the same as the GGS II/K14.

 

Director sights are relatively modern devices first coming into use on aircraft like the F18 and later model F16/F15. With a director sight own aircraft body rates (turn rates) arent as important as target line of sight rates are directly measured from radar (or I guess IRST in the case of Russian aircraft). These type of sights require modern computing power to determine an accurate solution that will dynamically apply true GD,TAS,and trajectory shift corrections as well.

Edited May 3, 2012 by IvanK

[Maximus_G]

Historical (which by definition is not real time :)

That terminology is used by mr. Shaw in "The Art and Science of Air-to-Air Combat".

It actually is real-time, as it gives us the point where our bullets would be right at this moment.

 

Director sights are relatively modern devices first coming into use on aircraft like the F18 and later model F16/F15. With a director sight own aircraft body rates (turn rates) arent as important as target line of sight rates are directly measured from radar (or I guess IRST in the case of Russian aircraft). These type of sights require modern computing power to determine an accurate solution that will dynamically apply true GD,TAS,and trajectory shift corrections as well.

The only difference between historical and predictor sight is its time setting: it shows the point where your bullets will be if you pull the trigger now, or it's the point where your bullets would be right now if you pulled it a bit earlier (1 bullet TOF earlier).

 

I have an RAF doc "Weapons notes for flying personnel Fixed gun sighting Air Phamplet No 252" that describes its operation clearly.

Would be great to see that description to clear it out. Can you share it with us?

[IvanK]

"That terminology is used by mr. Shaw in "The Art and Science of Air-to-Air Combat".

It actually is real-time, as it gives us the point where our bullets would be right at this moment."

 

But a straight out Gyro sight only shows where your bullets are 1 time of flight x the settling time ago. Real time sights are a relatively modern device.

 

The Document is in paper format not a digital one 50 pages.

 

 

I have used the following Sights. CSF97K in Mirage III Historical (Direct descendant of the GGS MK II)

Ferranti ISIS in MB326H Gyro sight Historical with fixed rang input.

F18 with both Director (requires radar lock) and LCOS without lock. Only the F18 operating in Director mode could be "considered' a real time sight. In Director mode it could also predict and give a shoot cue even with the director pipper off the target as it predicted a solution based on Pilot reaction time, gun spool up, and predicted bullet time of flight, and target LOS rates. Current F18 software is even more advanced with Bullets at target range (BATR) displayed ... same as late model F16/F15 etc.

Edited May 3, 2012 by IvanK

[Maximus_G]

But a straight out Gyro sight only shows where your bullets are 1 time of flight x the settling time ago.

That's the point. A gyroscope reacts immediately, so if we want to make a historical sight, we need to implement a time lag in its construction. It would be more complicated technically. While a straight-out gyro just points where the bullets will be in the future if you shoot now.

[IvanK]

That's the point. A gyroscope reacts immediately, so if we want to make a historical sight, we need to implement a time lag in its construction. It would be more complicated technically. While a straight-out gyro just points where the bullets will be in the future if you shoot now.

 

Yes I agree a totally free Gyro reacts instantly, but in this application we want the Gyros precession to output a smooth value that represents a deflection angle based on range and LOS rate. In the case of the Gyro gun sight the Gyro is operating under the influence of 4 magnets that modify the precession and output. This in effect introduces lag (settling time for want of another phrase). The result is a smooth controllable sight reference. I will scan the sections of the document that describe the operation of the gyro and the magnets and how they influence the gyro output.

[Yo-Yo]

That's the point. A gyroscope reacts immediately, so if we want to make a historical sight, we need to implement a time lag in its construction. It would be more complicated technically. While a straight-out gyro just points where the bullets will be in the future if you shoot now.

 

It can not react in moment. The gyro itself has MOI that obviously less than along the rotation axis but it is not negligable.

[keithb]

And I thought the Mustang was going to be simpler.......

Cheers

keith

[Maximus_G]

Yes I agree a totally free Gyro reacts instantly, but in this application we want the Gyros precession to output a smooth value that represents a deflection angle based on range and LOS rate. In the case of the Gyro gun sight the Gyro is operating under the influence of 4 magnets that modify the precession and output. This in effect introduces lag (settling time for want of another phrase). The result is a smooth controllable sight reference. I will scan the sections of the document that describe the operation of the gyro and the magnets and how they influence the gyro output.

Magnets apply the force that keeps the main mirror's default orientation inside the sight, and AFAIK the mirror reaction to the range and target wing span adjustments is performed via magnets too. But it seems to be nothing inside there to remember the gyro movement and resemble it some time later, no mechanism for the lag: http://www.ww2aircraft.net/forum/weapons-systems-tech/mk-18-gyro-gunsight-22613.html

 

It can not react in moment. The gyro itself has MOI that obviously less than along the rotation axis but it is not negligable.

OK, still we both have agreed that this sight shows us the future: the point where the bullets will be if we fire now :juggle:

[Yo-Yo]

Magnets apply the force that keeps the main mirror's default orientation inside the sight, and AFAIK the mirror reaction to the range and target wing span adjustments is performed via magnets too. But it seems to be nothing inside there to remember the gyro movement and resemble it some time later, no mechanism for the lag: http://www.ww2aircraft.net/forum/weapons-systems-tech/mk-18-gyro-gunsight-22613.html

 

 

OK, still we both have agreed that this sight shows us the future: the point where the bullets will be if we fire now :juggle:

 

Moreover, generally ANY EXTRAPOLATOR gives the info where the function will be at NOW+T moment regarding the data we know till the moment NOW... it's funadamental. :) But to have this point accurate the function must behave from NOW to NOW +T exactly as we presume. If the predictor is linear it must be linear , for example.

 

There is no different reaction for distance and wing span. THere is only 1 parametre - distance measured stadiometrically that goes into the sight as a current for electromagnets.

THere is no use to have any special lag because the fire solution is presumed to be for saddle conditions. The predictor itself is LINEAR so the best accuracy will be for constant angular velocity.

[IvanK]

If you want to believe its real time thats fine ... except any pilot trained on basic Gyro gunsights is told its not. Even the The F15 in LCOS mode(and we are talking about a far more sophisticated system than a K14) has a Lag line extending aft from the pipper. This in effect represents an analog "time to valid solution"..

If it was a real time sight then the instant the pipper was on should be a valid solution ... its not. Excerpt below from F15 Weapons manual.

 

 

In the second jpg from the same manual the input differences between LCOS and Director sight are stated... as I stated previously in that Director mode doesn't use own turn rate but LOS rates from sensors .. radar. the Director gunsight then becomes as close to a real time gunsight as you are going to get with current technology.

 

 

In the PDF some lo res scans (to keep it managable size) from the RAF doc describing the workings of the sight. This is not the full doc. Hope its of some use.

GGS.pdf

[flightace37]

Okay, I'm going to do my best to help clarify this.

 

A gunsight that causes the pipper to move around within the sight field of view (as opposed to a fixed sight) in response to the maneuvers of the shooter aircraft is sometimes referred to as a "disturbed-reticle" system. Within this broad category there are many variations. The type of LCOS which has been described attempts to predict the position of the target (LOS and range) at one TOF in the future and then displays a pipper that directs the pilot in providing the proper amount of lead. This type is known as a "director" or "predictor" sight. besides all these difficult predictions, the accuracy of this system is also dependent on the target maintaining a fairly constant maneuver (the closer to a straight line at constant speed, the better) for at least one TOF after the prediction is completed.

 

Another mechanization of the disturbed-reticle LCOS might be called a "historical" or "real-time" sight. This system only predicts the bullet trajectory and "remembers" this trajectory until its TOF would be complete. It then displays a pipper that represents the point of impact of that bullet on a geometric plane at the target's present range. Such a gunsight tells the shooter what is happening at the present time to bullets fired one TOF in the past, thus the term historical. If the pipper is superimposed on the target, bullets should be passing through the target if the shooter was firing one TOF earlier.

 

- Robert L. Shaw. Fighter Combat: Tactics and Maneuvering, pp. 13

 

The critical text is the very last line in the quote. The K-14A is not a predictor sight, because it only relies on own-ship motion (plus range) to judge bullet trajectory. Therefor, it is a "real-time" sight, in that it shows where the bullets would be right now, if you had fired one time of flight in the past. It is "historical" in the sense that it shows the current position of bullets fired in the past. Both terms mean the same thing; you just have to think about it a little differently.

 

The "historical"/"real-time" nature of the sight is not due to any mechanical devices inside it. It is solely because the sight is not predicting the position of the target in the future. That is the realm of "director" sights, and it requires some kind of understanding of true target motion, rather than just own-ship motion. This is achieved by a radar lock, or some other kind of tracking and ranging system, and even with that, it is not perfect. (The target can still squirm in 1 TOF).

 

Shaw goes on to say:

With a historical sight, the pilot must remember to open fire at least one TOF before the pipper appears to touch the target on the sight unit in order to get the maximum number of hits. Tracking can also be somewhat more difficult, since there is a lag of one TOF between the movement of the shooter and a change in the pipper indication. The pilot has little control of the pipper (just as he can't control the flight path of the bullets after they are fired) for fine tracking corrections.

 

- Fighter Combat, pp. 14

 

The advantage of the "real-time" sight (I like that term better), is that you can open fire 1 TOF before the pipper is on the target. When the pipper then touches the target, the bullets will hit the poor bugger. "Predictor" sights cannot do this, because they show you where to aim to hit the target 1 TOF in the future. (Yes, the pipper is still typically placed on the target, but it could just as easily give you an arcade-style "lead" dot to place your bore-sight on).

 

Lastly, remember the "settling time" that Ivan mentioned. The sight has a small interval that it requires to actually move the pipper to the correct position. Ivan said this interval was 1.2xTOF. I believe that it is actually 0.2xTOF. So, for the bullets to hit the target, you actually need to have fired 1.2xTOF in the past, rather than just 1xTOF.

 

To look at it another way:

If you are waiting to open fire with a steady-state tracking solution, you have to wait 1.2xTOF for the pipper to move to match the steady-state situation before you can pull the trigger. The situation then has to be exactly the same for another 1.2xTOF until the bullets pass through the target's range at the pipper position.

 

One last way to look at it:

If you had an unlimited supply of bullets and were constantly holding down the trigger, any time the sight touched the target (less the 0.2x settling time), bullets would hit it. All assuming perfect ranging, etc.

 

And a final anecdote:

The K-14A does not have any kind of computer memory, so it cannot show you the actual position of bullets fired one TOF in the past. Instead, it takes its best guess based upon current maneuvering conditions. This is why you have to set up a steady track and wait for the sight.

Edited May 4, 2012 by flightace37