Author Topic: Vertical gun settings. (Read 1698 times)

Redbone · « **on:** July 20, 2000, 08:22:00 AM »

Besides convergence, I'd like to set the height of the point of convergence. Is there a way to do this?

an example:

p47

guns1&2 @ 650 dead center
guns3&4 @ 500 -2 ft
guns5&6 @ 500 +2 ft
guns7&8 @ 450 dead center

This would offer more of a shotgun effect.

LLv34_Snefens · « **Reply #1 on:** July 20, 2000, 10:14:00 AM »

In short words, no.

However, altho you can not directly set the height of the bullets, there is a work around.

Convergence is not just the position where bullets from two guns on each wing cross each other. It is also where the bullet drop below the gunsight. For instance convergence for a nose mounted gun is not irrelevant.
To make it more clear, presume you fly straight and shoot. The moment the bullets leave the barrel gravity will affect them and they start to drop. Therefore the guns are pointed slightly upward so the bullet first crosses the gunsight line some hundred of yards out. In this game the two types of convergense (vertical and horizontal) is the same. I can imagine it was possible to seperate the two in real life.

Now to get back to your example you can't get it exactly like you wanted, but you can go somewhere close to it. The 4 guns you have converging at 500 yards should be set to other than 500. If you set it to more the bullets will be higher than the crosshair at 500, and if you set it to less the bullets will be lower than your crosshair when reaching 500 yards. Problem is now that the bullets don't converge at 500 but will be a little apart.

You already have the shotgun effect actually. Your guns converging at 650 will be higher than crosshair at 500, and your 450's will be lower.

Something to keep in mind also is that since it is gravity that creates the vertical seperation, shooting while not level (banked, diving etc) will make the bullets fly different than explained here.

Snef

Redbone · « **Reply #2 on:** July 20, 2000, 10:34:00 AM »

Thank You very much Snef, I completely forgot about trajectory. I appreciate the response.

Minotaur · « **Reply #3 on:** July 20, 2000, 02:56:00 PM »

Snef;

A bullet will always fly the same trajectory. It is your perspective in relation to the bullets trajectory that makes it appear to be different.

EX1: Straight and level flight, your bullets appear to drop only due to gravity in-line with your flight path.

EX2: Pulling 4g's, your bullets appear to curve away from your flight path. The bullets however, are not curving away. They follow the same trajectory as in EX1.

The plane movement and the pilots perspective is what causes this noticable effect.

------------------
Mino
The Wrecking Crew

"So what do you post here? Poetic love letters?"
Ram

[This message has been edited by Minotaur (edited 07-20-2000).]

Andy Bush · « **Reply #4 on:** July 20, 2000, 08:53:00 PM »

Well...here we go again!!

Redbone

Don't worry too much about your 'shotgun effect'...you are going to get that anyway due the to dispersion of the guns. Your desired values (+ or - 2') is well within the typical gun dispersion of WW2 guns. For more on dispersion, see the A2A Gunnery articles in the Air Combat Corner at www.simhq.com.

As for convergence...the correct term is harmonization. Harmonization usually dealt only with the lateral adjustment of gun lines. Any vertical adjustment of gun lines is usually referred to as 'boresighting'. Fuselage mounted guns were normally only boresighted, not harmonized using the definitions I just used.

Not all guns were boresighted. This is not a simple subject,and much depends on the physical location of the gun versus the gunsight. If there was a significant height (vertical) difference between the gun line and the sight line, then the gun would be boresighted for a given range.

As for apparent projectile ballistics, Mino is correct. Once the round leaves the barrel, its behavior is fixed...the only thing that changes is how it looks to the pilot depending on bank angle and G load.

We're getting wrapped around the axle here with pissants. If you get in close enough (inside 1000'), the factors that affect the projectile line of the gun become less significant. Range is not the driving factor...time of flight is...and at these ranges, your TOF is down around a half second or so. In a low G firing situation, the dispersion cone is going to be much smaller than the target size...and harmonization is going to have less significance. Just get the lead right and you'll hit the target.

Andy

[This message has been edited by Andy Bush (edited 07-20-2000).]

Duckwing6 · « **Reply #5 on:** July 21, 2000, 03:00:00 AM »

Re: Boresighting .. i don't think that in AH the Convergence setting also boresights the guns at the desired distance e.g. i don't think that the Bullet stream will converge in the center of the gunsight when you vary ranges .. i could be wrong tho...

Minotaur · « **Reply #6 on:** July 21, 2000, 09:02:00 AM »

One farther comment, I believe that Indian explains it quite well. Indian says "Shooting your guns is like using a water hose".

Lets say you are going to water a plant and you only get 2 seconds of water flow from your hose.

If you point the hose at the right spot, you can get most of the water on the plant. This would be the above EX1 of straight flight path to target.

However, if you swing the hose past the plant you use the same amount of water, but not much goes on the plant. This would be EX2 where the plane is under G load.

Too make matters worse, say that the plant is moving in a way opposite the movement of the hose. You can definatley hit the plant, but with hardly any water.

A third way is possible and happens frequently. This case is where you are moving the hose at the same rate that the plant is moving and in the same direction.

In this case, you and your target are both under G load and also manuvering in the same plane of motion.

BTW Andy has put up a very good discussion of this. A good read!

All in all this is probably much more information than what was oringinaly requested, but I am sure it won't hurt anyone to know it.

Good Luck!

------------------
Mino
The Wrecking Crew

"So what do you post here? Poetic love letters?"
Ram

Andy Bush · « **Reply #7 on:** July 21, 2000, 09:10:00 AM »

Mino

Your use of the water hose analogy is dead on. I used the same ideas when I taught the subject in the FWS.

I used to tell the students to imagine holding a water hose up to their nose so that they were looking down the stream of water. Then I would tell them to move the hose and watch the stream pattern...that water stream is exactly what happens to gunfire!

Corny...but it makes the point.

Andy

[This message has been edited by Andy Bush (edited 07-21-2000).]

LLv34_Snefens · « **Reply #8 on:** July 21, 2000, 12:10:00 PM »

Redbone, ok you better listen to Andy here. He knows what he is talking about.

Mino, I didn't mean to make it sound like the bullets flew with a different/curved trajectory, but I can see how my last comment make it sound like that. I just meant that if he flew other than level (don't even have to push G's) the bullets won't place themself compared to the gunsight like I told above. Flying level but inverted for instance, they will never pass it.

Duck, Actually I just heard it somewhere that it was implemented and took it for good merchandise. I did a little testing just now but I couldn't really deciede if the bullets really did fly higher when convergence was set to 650 compared to 150, because of the rather big dispersion of the guns (anyone know what guns have the smallest dispersion?)

Snef

Duckwing6 · « **Reply #9 on:** July 22, 2000, 04:08:00 PM »

Well can't say really for dispersion but highest stream density i'd say has the Cal 50s (maybe the 303's but i'm not sure as i hardly ever use them) On the other hand they have the flattest trajectory anyways so the effect wouldn't be so pronounced....

Andy Bush · « **Reply #10 on:** July 22, 2000, 04:23:00 PM »

Duckwing

Check out this site...it has some very good gun info.
http://www.geocities.com/CapeCanaveral/Hangar/8217/fgun/fgun-fr.html

Andy

Sorrow[S=A] · « **Reply #11 on:** July 23, 2000, 04:30:00 AM »

Guy's- Pyro has stated before that convergence settings DO affect the guns vertical aim. ie. a 650 conv has a higher trajectory than a 250 one. Thus I always put slow nose cannons to 500+ (a trick I regret I showed zigrat hehe) as during high G there is a notable difference in where they strike. By this I mean if your CONV is at 650- and your target is at 300 the impact is above where it would be if your conv was at 300. A minor trick but right handy one if your trying to hit with 30mm or 20mm in a G turn as it means that slightly smaller amount of lead under your nose before the shells hit.

(and YES I know that conv on nose guns is total BS... but it's there- use it as you will)

Waxer · « **Reply #12 on:** July 25, 2000, 05:20:00 PM »

For gawd's sake...! No *wonder* I've been missing so badly from the dead 6 o'clock position. I thought I had rubber bullets.

Thanks for clearing this up!

aircat · « **Reply #13 on:** July 27, 2000, 03:59:00 PM »

even with trajectory ect. one thing that makes the biggest differance is your AIM.. lots of people spray and prey with thier guns on 3 or 4 convergance settings I use one for all guns (if all same gun type) makes a hella impact when I hit.

Duckwing6 · « **Reply #14 on:** July 27, 2000, 04:24:00 PM »

Thanks for the link andy

pretty good info ..

Author Topic: Vertical gun settings. (Read 1698 times)

Redbone

Redbone

Sorrow[S=A]

aircat