Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: GODO on August 31, 2004, 07:30:23 PM
-
Is convergence affecting both planes, horizontal and vertical? If so, does it means that setting it as close as possible would increase noticeabily the elevation of the rounds past the GS center?
-
As I understand it harmonizanion means that bullets will converge at the center of the gunsight at the convernge setting.
If thats true then it should mean that extreme close in harmonization should elevate the guns.
-
Wouldn't it be the other way round?
-
Well I don't have experience boresighting guns but I do have experience boresighting other aircraft items. Few things I have experience in is heads up displays, LANTIRN Targeting Pods, ring laser gyro inertial navigation units, and standard gyro assemblies.
I have to adjust in both azimuth and elevation on all of my units. I would think that the basics would cross for guns themselves. You should be toeing it in at closer ranges and as you go further out to the last gun on that wing you may have to adjust slightly in elevation. Obviously this depends on the wings and how they are shaped too. Inner guns on a wing that has a lower heigth at it's fuselage would actually have to be brought up some where as the outer guns may have to be brought down some.
It really depends on the platform. As you set your convergance further out your going to have to make toe out and elevation adjustments to calculate for bullet drop. Again I've never boresighted guns themselves. But the basics should be the same.
Also many of the newer gunsights could adjust for distances and aircraft just be a turn of a dial. A base set convergence was done. And the lead computing sight had certain size and distance settings for aircraft and range. Take a look at the Pony Ds sight and you'll see what I mean. Basically you'd have the ability to adjust your sights on the fly.
Also I thought harmonization is only for nose mounted weapons. It's so that the guns are in harmony with the revolutions of the blades themselves. So obviously you don't shoot out your own prop. Granted harmonization could also be meaning that they all hit at a relative area at certain distances.
-
I hate helping the opposition, but you seem like nice folks, even though you try to kill me every time you see me :)
Take a look here for a great explanation of convergence...
http://www.simhq.com/_air/air_031a.html
-
Yes convergience does effect elevation.
Setting large cannons LONGER than mgs can result in both hitting at the same spot.
I think it also helps a bit in deflection shooting. Not a LOT, but a bit.
Use the .target 300 command and your favorite plane & do some experimenting.
-
Historically, some planes were able to adjust both, horizontal and vertical. Harmonization is related ONLY to the vertical plane, not horizontal (convergence is horizontal).
For example, in real life, a 190A8R1 had the horizontal convergence for gondolas set at 800m and 600m for wing root guns. But the harmonization was set to 550m for all the guns. So, vertically, all the guns were set to cross the gunsight center at 150m, from that point, the rounds were going well above the gunsight center until 375m and then going down and crossing again the gun sight center at 550m.
AH doesnt allow us to control gun harmonization, only convergence, but then 99% of the rounds fired never go above the gunsight center to fall further.
So, the real question is how manages AH gun harmonization when we can only set horizontal convergence?
-
HERE (http://www.netaces.org/ahweapons/weapons.html#title) are the results of some testing I did on various weapons. The tests were done in AH1... don't know what, if anything, has changed, but I will get around to doing AH2 tests at some point.
Hammer
netAces.org (http://www.netaces.org) - Tips, Tactics and More!
-
and HERE (http://www.netaces.org/ahconverge/converge.html#title) is page on effects of convergence.
Hammer
netAces.org (http://www.netaces.org) - Tips, Tactics and More!
-
Mandable: Can you give me your diffinition of harmonization?
HiTech
-
hitech, it is not my definition. German documents for 190A8 gun patterns show convergence range as horizontal crossover range (where the rounds cross horizontally the gun sight, and harmonization range as the point where the rounds cross vertically the gun sight going down (not the point where the rounds cross vertically the gun sight going up).
For the pair of MG131, harmonization range was set to 400m but these MGs were set parallel, so they dont converge horizontally. This way MG131 rounds reach a maximum elevation of 40cm over the gunsight center at 200m, crossing the gunsight again going down at 400m (harmonization point).
For the MG151/20, harmonization was set to 550m while convergence (horizontal crossover) was 600m for inner guns and 800m for the outer guns, well below the gunsight center in both cases.
In any case, every single round should have a range where it is flying above the gunsight center, and 2 points where the round cross it vertically.
-
Isn't there a .t or .target command? There used to be.
-
A more clear picture, this time with six 20mm guns and 2 MGs:
190A8 six guns aligtments (http://www.terra.es/personal2/matias.s/190-gun-2.jpg)
The picture also shows a table with the horizontal (S1, S2, S3 and S4) and vertical displacements (H1, H2, H3 and H4) of the rounds from an imaginary line along the fuselage from 0 to 100m. The horizontal distance between that line and the MG131 rounds is 13cm all the time while the elevation raises to 142cm at 100m (about 40cm above gunsight center at 100m).
-
Ok to answere your question is the convergance and harminazion are always set to the same number in AH.
HiTech
-
yes Ra .target xxx where x = range in yards.
0 to make it go away.
-
Originally posted by hitech
Ok to answere your question is the convergance and harminazion are always set to the same number in AH.
HiTech
Not sure about that. What I see is that the bullets cross the sight vertically for first time at the convergence point (bullets climbing), going then down. So, setting conv at 600 yards makes the bullets to raise along 600 yards, touch the gunsight center and then go down.
But the real bullet pattern is quite different, they raise much earlier (125m) over the gunsight center, fly above the gunsight center and then cross the "convergence point" going down form above at 550m. Most of the time the rounds are above the gunsight center.
Actually, my impression is that my rounds in AH fly lower than gunsight center until convergence range. Then they more or less cross vertically and horizontally and go down. The effect is that firing closer than convergence puts the rounds too low, firing farther puts the rounds too disperse.
-
After looking at that chart and re doing it in color it seems there is a rather large spread of bullets.
Maximum coverage area at the 550m harmonization line for all guns combined other than the MG131s is approximately 2m. Spread from one wings outer gondola to the same wings inner gondola is just under half of a meter. From the inner gondola to the wing root MG151 there is a little over a half meter spread. While the MG 151 wing root mounted gun will be right on the sight line at 550m.
All of this is ofcourse under no wing loading (symetrical or assymetrical) and with a perfectly boresighted weapon system. A 6 foot area of bullets at 550m is great but that is only if there is no outside interferrence with the preset boresight. Question is how much wing flex is induced under a certain amount of Gs? This could very easily throw off that boresight and hits could be outside the original ball park and not as accurate.
-
Godo do mean something like this?
Per your chart your preset boresight range is at 550m and your target is at 500m. Your bullets flight path is now technically higher than your sight line by almost 40cm or 15.75 inches with a target at 500m.
While in flight your bullet will be passing through your sight line from bottom to the top at 140m then going back to the sight line again from top to bottom at 550m. This in essence would mean you would have to push the nose over approximately 40cm to hit your target at 500m. At 350m you'd have to push over even more to almost 80cm and then you'd be backing off to 40cm again at approximately 220m and finally back to line of sight at about 150m with no adjustment.
Question is do we model our lead computing sights like we should? Adjustments on your sight would adjust your targeting reticle to the appropriate postion and then you'd essentially fly to your targeting reticle depending on what you guesstimate your range is.
The P-51D had preset reticle adjustments for particular aircraft during the war. If you knew what plane you were dealing with you'd make that selection on your sight . You'd then adjust your range scale to make the aircrafts wing tips fit snuggly between your reticle. Once you did that you'd know at approximately what range the target was at. Granted the reticle could not be preset for every possible encounter so the major aircraft were preset. When the pilots would find a different bird other than a preset one they'd have to know approximate wing span so as to select the appropriate preset selection. This would give them a best guess range instead of having to judge solely by there eye sight and what they thought the range was with no help from out side sources.
-
I prefer my guns to harmonize in 3rds or 5ths.
Some people like weird stuff like 7ths but that is too 'outside' if you know what I mean.
-
Godo if HT is stating that the harmonization point and the convergence point are the same then technically I would think they aren't correctly modeled. But that doesn't necessarily mean the spread spectrum isn't induced at the convergence point.
With your reference chart you should have a total of 3 meters of total coverage area. The only thing you could do is with this chart setup the same bird at the same harmonization point and check to see if the spread spectrum is almost the same. If your getting a very tight grouping at that range that doesn't match up then something is definately modeled incorrectly.
Basically I'd try firing your wing root cannons first and check their spread spectrum at that range. See if it's roughly the same. It should be a tight grouping right on at 550 meters. Then fire your gondolas at the same range. Not sure if you can fire each seperately (inner and outer) but you could definately tell if the spread was close to being accurate. Your outter gun should be almost a meter off of center at 550m. Your inner guns should be almost .80 meters off of center.
To check for atleast the wing root accuracy dial in 400 meters on your target. Your MG131s should be slightly off center left and right with the convergence (400m) set at 400m on the target since they are in parallel. They should never be dead on center. On that same target check your wing root cannons. They should be almost .4 meters off center at 400 meters with their convergance still set at 550 meters.
At a 400/550 meter convergence set your target 400 meter total spread spectrum should go out to about a little over 3 meters or so with all guns firing. With that same convergence set your 550m spread spectrum should be no more than 2 meters and your MG131s shouldn't even come close to hitting the target. With their 400 meter harmonization point their bullet drop should easily exceed 120cm below the sight line. Then again I have to check and see how many centimeters the target reference board is on AH2. They may hit but they'd be extremely low on the board.
-
Well I did a quick test. Without knowing the range circles and what distance high and low off center it's hard to come up with a conclusion. I did notice though at 400 meters my cannon rounds would have more hits below the zero reference mark than they would above. Here's the other kicker though the A-8 we have doesn't have gondolas. So therefore the test isn't accurate.
If the gun mount areas were about the same which they may be in distance (width off center)but not elevation wise on the wing I could say it shows that the rounds are actually hitting lower instead of higher at 400 meters. At 400meters I should have been almost 80cm higher than the 0 reference point. that equates to almost 2 and a half feet higher. Again without knowing how the board is setup as far as the reference circles it's hard to tell. Also without having a graph for this particular aircrafts configuration that we have available it's also hard to tell.
-
Do not foget how speed changes the trajectory. Guns are set while the plane is standing still. The outcome will change as you fly faster or slower.
HiTech
-
Cool thread. Very informative.
-- Todd/Leviathn
-
Originally posted by hitech
Do not foget how speed changes the trajectory.
HiTech, speed is not the point here, the speed of the plane relative to the speed of the rounds is very low and will rarely affect the bullet trayectory over or below the gunsight center (AOA from speed affects both, gun elevation and where the sight is pointing). The point is that bullets should fly over the gun sight center most of the time and then cross it going down at convergence range (being convergence and harmonization at the same range), just the opposite than to cross the gunsight center going up at convergence range and then falling to the ground from that point.
Cobra412, 40cm at 500m are hardly noticeable from the pilot eyes over the gunsight center, you really dont need to push your nose down to hit the target. May be you will hit the engine and the cockpit instead the tail while aiming directly to the tail. But, if the bullets are traveling lower, you are going to miss any centered target that is flying closer than AH convergence point and then you really need to pull your nose over, even losing partially the target from view to score hits.
-
Mandabole: The resone for not going much above the sight is do to the eye point on most planes is well above the gun point.
Let say you have convergance to 500 yards. And a 2700 fps round.
That bullet will reach 500 yards in aprox .5 secs.
That equates to a drop of 4 feet from the bore line.
Now if your eye is 4 feet above the gun, the bullet will never be above the slight line until possibly after 500 yards.
At 300 yards the drop from bore sight line would only be only 1.75 feet hence it would be even more pronounced. In order for the bullet to travel threw the sight line and back down at closer ranges, I would almost have to be shot straight up.
HiTech
-
I did more tests using only the wingroot guns of 190A5, convergence set at 550 yards (historical harmonization was 550m), constant speed of 330mph at 1000 feet alt.
With the target set to 200 yards, hit concentration was clearly below gunsight center. with the target set at 400 yards, hit concentration was near the the gunsight center, with the target at 550 yards, gun concentration was noticeabily below the gunsight center. In any case, all the rounds hit the target to the left of the corresponding hit point, that is, right gun near gunsight center horizontally and left gun well to the left of gunsight center.
IMO there is a problem with the gun placements in 190s. Bullets go too low and to the left all the way until convergence range.
-
Originally posted by hitech
Mandabole: The resone for not going much above the sight is do to the eye point on most planes is well above the gun point.
HiTech, the graph I posted has several horizontal lines, for the gun, for the plane and for the gunsight (and the pilots eyes). It is showing clearly that most of the bullet path is above gunsight center line, not below it. May be the effect is different in other planes, but this is how it worked for 190s and probably for 109 gondolas too. The bullets should cross the gunsignt going up really early, not just at the convergence point where they should cross it going down. May be it is due a wrong placement of the guns or a wrong ballistics for 151/20s, dont know.
Aside of that problem that really affects negatively the aming with these planes, it would be good to have an indication in the hangar when setting the convergente to show the harmonization point (the point where the bullets will go down the gunsight center falling from above).
-
Originally posted by hitech
Now if your eye is 4 feet above the gun, the bullet will never be above the slight line until possibly after 500 yards.
Wrong, as you can see in the picture the bullets will start to fly above the gunsight center at 125 yards and will go down the gunsight center at 550 yards (with harmonization set to 550 yards). The guns are clearly pointing up.
-
Originally posted by hitech
Do not foget how speed changes the trajectory. Guns are set while the plane is standing still. The outcome will change as you fly faster or slower.
HiTech
My translating could be faulted. Velocity relative to target not airspeed is the factor yes?
AH# tiger3
-
Harmonization - derived from Harmonize meaning 1)to make harmonious: bring into agreement 2) to sing in harmony 3)to add chords to a melody so as to form a harmony 4) to arrange into a Harmony(sense)..
I think #1 best qualifies for what you are looking for HiTech
Wsky
-
Did some checking, turns out was doing a simple estimator for the amount of bullet drop when setting up the harmonization. This had the net effect of bullets shooting about a foot low on the fw at 550 yards. Change it to a more precise method and turn off bullet dispersion to see the results.
Here they are, they match mandobles table.
(http://www.hitechcreations.com/hitech/fwgun.jpg)
Note made a typo on the image convergance was 550.
HiTech
-
Redid the tests again (190A5 inner guns only at 330mph). 150 and 200 yards target rounds hitting clearly lower than GS center, at 500 yards all the hits vertically near the center. Is dispersion putting the rounds lower most of the time?
-
How does default forward head position play a roll in all of this if any? meaning if someone accidently moved their forward looking head position and saved it or got it just a bit off, but to where you still saw the bore sight good....would this cause 2 people to see 2 different views? I mean you have already set your convergence in the hangar, but have you set your head position for the convergence of the guns?
or tested to make sure they are passing the center bullseye of your gunsight....
or does this not matter?
( tell me to shut up and go crawl under my rock if all this means nothing :) )
-
Hitech wrote. This had the net effect of bullets shooting about a foot low on the fw at 550 yards. Change it to a more precise method and turn off bullet dispersion to see the results.
Like I said mand, current method shoots about a foot low.
HiTech
-
Originally posted by hitech
Like I said mand, current method shoots about a foot low.
HiTech
HiTech, 1 feet too low from where? gunsight? expected flight path of the rounds? With dispersion? Without dispersion?
All I can say is that the german pattern shows an elevation of 2.6 feet above gunsight line from 300m to 400m, 1.3 feet above GS center at 480 yards, 0 at 550m. There are two intersections of the gunsight line: 120m and 550m.
Of course I cant turn off dispersion but every bullet concentration point is below or near gunsight center with 550 yards as convergence. May be I'm performing the tests wrong but what I expected, even with dispersion, is having all the bullet concentration above the GS line from 120 to, at least, 450m (taking into considertion that the target is keeping your speed and flying away your firing position).
-
Mand: Wake up, im agreeing with what you are seeing, the picture is after I made a change today for the next patch.
HiTech
-
Ok, now I understand, thanks a lot.
-
Originally posted by hitech
Mand: Wake up, im agreeing with what you are seeing, the picture is after I made a change today for the next patch.
HiTech
Thanks HiTech for agreeing to take the time to fix it. And thanks Mandoble for taking the time to bring it up without p-ing anyone off :).
mauser