PDA

View Full Version : Gunsight



VC81_GLIDER
11-29-2004, 01:44 PM
Can someone please explain the various rings and markings on the Gunsight in the Wildcat/Hellcat? I can't seem to find anything and though "I think I know" I am not sure.

Thanks.

R_Mutt
11-29-2004, 02:12 PM
shift F1!!....oh wait sorry http://forums.ubi.com/images/smilies/59.gif

Soulyss
11-29-2004, 04:05 PM
The simple answer is that various tics and such on the gunsight represent a unit of measure "mills" (or somthing like that). If you know the approximate wingspan of your target you can gauge range.

killer2359
11-29-2004, 10:58 PM
Yeah, the radial markings give a reference for range to be calculated. Based on knowing / estimating the dimension of the target (or part of it) then the reticle markings help estimate it's range.

Being able to judge range and relative lateral distances helps the pilot concentrate fire and judge/calculate deflection shots, plus make fairly precise allowance for bullet drop (the later probably more important for strafing ground targets - tho also useful for straight attacks on air targets where there's no maneovering taking place).

There were sights with adjustable range ring - ie. it could be switched to whatever setting you wanted (ie. the ring would expand or shrink). - I understand some of these sights even had this adjustment connected to a twist grip on the throttle. With these sights I gather the pilot could set the ring to represent a given dimension and then by adjusting it to match that dimension on the target the range could be read off - or alternatively he could set the ring to represent a given dimension at a given range such as the gun convergence range. I think this would have been the primary reason for that type of sight - ie. it could be adjusted for different gun convergence or for extreme range shooting or for various munitions. I guess all up this type of sight does no differently to a fixed one with a number of concentric rings and/or radial "tics" - but it's much less cluttered and in the case of being able to read off ranges does partially automate some of the otherwise mental calculations that would be necessary.

The next development was sights that compensated for G forces - I think called "Inertial" sights where the visible reticle floated around according to how the aircraft was maneovering - ie. pulling G's it'd be sinking down toward the nose and if there was some sideslip happening then it'd also be moving off to the side etc. - and at the same time the pilot could carry out reticle size adjustments as well. Pretty sure the P-51D had this sort of sight??

All in all, the technology of WW2 era fighter gunsights and their usage is a LOT more involved than ANY sim to date has managed to represent - but PF once again excells as described by Athosd below.

Athosd
11-29-2004, 11:55 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by killer2359:
All in all, the technology of WW2 era fighter gunsights and their usage is a LOT more involved than ANY sim to date - including PF - has managed to represent. <HR></BLOCKQUOTE>

The late model P51D-N-20 included in FB+AEP has a very nice K14 gyroscopic "predictor" gunsight. The floating reticule can be adjusted for range and target wingspan - its a great piece of work.

killer2359
11-30-2004, 03:46 AM
OOPS! - sorry about that - I hadn't tried the later aircraft yet - I've edited my post. Once again I unreservedly apologise for that.

Athosd
11-30-2004, 04:06 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by VC81_GLIDER:
Can someone please explain the various rings and markings on the Gunsight in the Wildcat/Hellcat? I can't seem to find anything and though "I think I know" I am not sure.

Thanks. <HR></BLOCKQUOTE>

The sight image is composed primarily of two deflection rings - as printed above the reticule (for the F4U anyway) the outer ring is 100 Mils across.

100Mils describes an arc of 100m at a distance of 1000m (6400 Mils = 360 degrees, more on this later) - or 10m at a distance of 100m.

The inner deflection ring is half the size, 50 Mils, so it describes an arc of 50m at a distance of 1000m - or 10m at a distance of 200m.

The average wingspan of fighter aircraft is around 10m. So the two rings serve as a very handy range finding tool.

The horizontal tick marks that run down through the sight's centre are spaced at 10 Mil intervals. These can also be used for ranging - though less intuitively than the deflection rings.

The horizontal line shows your wing line - handy for aligning yourself with the target (wings in the same plane). Recommended for best results with aerial gunnery - particularly with wing mounted weapons.

The angled lines in the lower half of the sight image - radiating from the centre - indicate your gun lines. Rounds from your wing guns will travel roughly at that angle until convergence at the centre of the sight (gravity etc notwithstanding). These are very handy aids for lead computing.

[Edit] - those lines are actually just 45 degree lines, meant to assist with angle vs horizon determination - though I use them as gun lines and they work quite well.[End Edit]

As mentioned previously there are 6400 Mils in a complete circle - and 1 Mil is very nearly 1m of arc at 1000m. The figure is arrived at simply by rounding pi to 3.2 (instead of the less wieldy 3.1415927......):
Circumference of a circle is 2 x pi x radius - hence if pi equals 3.2 the circumference of a circle with radius 1000m is a very convenient 6400m.
This certainly introduces an error factor - but its insignificant for practical applications that use this measure (there's always degrees, minutes, seconds for precise navigation).

Hope that helps.

Cheers

Athos

killer2359
11-30-2004, 04:44 AM
Excellent description Athosd!! - that's the fixed USN type sight - the adjustable types are fascinating in their operation and theory.

I've just had a bit of a check of various aircraft - it looks like only a few later planes have realistic adjustment facilities - it'd be nice if all the adjustable gunsights could be actually adjusted - but where do you stop! I think 1C:Maddox have done a fine job with what we've got when all's said and done.

VFA-195 Snacky
11-30-2004, 05:43 AM
Set your convergence close and fire only when you can read the serial number on the back of his plane.

Athosd
11-30-2004, 04:46 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by VFA-195 Snacky:
Set your convergence close and fire only when you can read the serial number on the back of his plane. <HR></BLOCKQUOTE>

That works, but if you have a weapon that can kill your foe at 500m why use a bayonet?

Also the original, conspicuously absent, poster requested a description of the gunsight's visual elements.

Blottogg
11-30-2004, 10:31 PM
Thanks for the excellent summary Athosd. I had wondered what the mil diameters of the U.S. sights were (the later USN sight especially.)

LEBillfish
12-01-2004, 09:08 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Athosd:

The sight image is composed primarily of two deflection rings - as printed above the reticule (for the F4U anyway) the outer ring is 100 Mils across.

100Mils describes an arc of 100m at a distance of 1000m (6400 Mils = 360 degrees, more on this later) - or 10m at a distance of 100m.

The inner deflection ring is half the size, 50 Mils, so it describes an arc of 50m at a distance of 1000m - or 10m at a distance of 200m.

The average wingspan of fighter aircraft is around 10m. So the two rings serve as a very handy range finding tool........... <HR></BLOCKQUOTE>

http://forums.ubi.com/images/smilies/53.gif..............Duh...yup, whatever he said uh-huh, I think maybe....What did he say again?

(seriously am going to have to let that sink in, looks interesting though as hows and why's make things clear. Just had to prove my ignorance first http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif)

VC81_GLIDER
12-01-2004, 11:15 AM
Athosd,

Thanks for the great info. Exactly what I was looking for..... and here I was trying to be inconspicuous http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif !!!!

Another question while we're on the subject here... what is the best 'typical' convergance settings for the guns... I have read somewhere that 300m should be used for guns, 500m for rockets. What is your opinion?

BTW- Billfish you definitely get best sig award http://forums.ubi.com/images/smilies/heart.gif

~S~
VC81 Glider

Athosd
12-01-2004, 07:29 PM
Hi VC81_Glider

Best convergence settings vary a great deal - and there many many opinions on which is best. There are likely to be a number of old threads featuring in depth discussion on this subject.

You could try searching for them, or if feeling lazy just start another one http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Note that "convergence" in the IL2 series includes both azimuth and elevation in the one setting. Hence it impacts centre line weapons too.
The range you select is where you want your rounds to cross the centre of your gunsight.

In general I go with 200m convergence for air to air and 400m for air to ground. But that changes depending on the type of aircraft etc etc.

Cheers

Athos