Gun sight image size analysis

[whiteman]

Nice work guys, i have a headache after reading some of it but nice work!

[Saxman]

I've made a new version of the US Mk.VIII gunsight:



This should be VERY accurate. The large ring is 100mil, the middle at 50. I've double checked and confirmed the hash marks are spaced at 5mil intervals.

I wish I thought to check the size before HT requested how big to make the max sight picture, as the Mk.VIII is a 150mil sight. I DID do a version that's the full sight, if anyone wants it, although that won't be quite as accurate. I suppose it's too late to request the size be increased from 128mil....

[hitech]

I didn't see it but on elevation with convergance.

AH sets the elevation of the guns to cross the slight line at the convergence point.

But it does convergence and elevation calculations from a stationary plane at sea level.

As you change elevations and speeds the ballistics will change. And hence can hit high or low at convergence distance.


HiTech

[Baumer]

Here is a chart that will help explain using the rings to estimate lead. Note this is for a target at 200mph as I post in the Wiki this will be more detailed.

Be sure to right click on the image and select "view image" to see it at it's full size, to make it easier to read. This is from a post war fighter gunnery manual but it gets the point across well.



Saxman did you find any documentation that it's a 150 Mil sight? It would be great to know what the source is to help convince HTC to change it, but I suspect it will be 128 Mil for now.

[BulletVI]

 HEHEHE i didnt find a thing apart from the acctual power and so on so for every machine gun used in WW2 lol me a bit thick at the Moment  
 

[Saxman]

Here is a chart that will help explain using the rings to estimate lead. Note this is for a target at 200mph as I post in the Wiki this will be more detailed.

Be sure to right click on the image and select "view image" to see it at it's full size, to make it easier to read. This is from a post war fighter gunnery manual but it gets the point across well.

(Image removed from quote.)

Saxman did you find any documentation that it's a 150 Mil sight? It would be great to know what the source is to help convince HTC to change it, but I suspect it will be 128 Mil for now.

Baumer,

You can tell from the hash marks:





If the outer ring is at 100 mil, that means Each hash is at 5mil intervals. If you count in 5mil increments from the pipper, you have have rings at 25 and 50mil radius (with diameters of 50mil and 100mil rings, respectively). The bottom hash is at 75mil from the pipper, for a diameter of 150mil. Even though there's not a corresponding ring, the diameter of the full Mk.VIII sight is still 150mil (the diagonal lines on the sight also fit to a 150mil ring).

So maybe 256mil max might have been a better choice, that way a 256x256bmp would give 1px/mil

[RTHolmes]

AH sets the elevation of the guns to cross the slight line at the convergence point.

But it does convergence and elevation calculations from a stationary plane at sea level.

As you change elevations and speeds the ballistics will change. And hence can hit high or low at convergence distance.

finally an explanation that makes sense! ty

[Baumer]

I'm sorry but I think HTC will need something more than a photo of a sight at the Air Force Museum to prove that you would see the full 150 Mil on a MkVIII. I'm not saying you're wrong, I'm just saying that we need to find better documented evidence to support it. BTW I like how the MkVIII is setup at the P-47 display, I wonder if Stoney or any of the other Jug experts can elaborate on which 47's used the MkVIII sight?

[Saxman]

I'm sorry but I think HTC will need something more than a photo of a sight at the Air Force Museum to prove that you would see the full 150 Mil on a MkVIII. I'm not saying you're wrong, I'm just saying that we need to find better documented evidence to support it.

When did this become Wikipedia? We've already established the rings on the Mk.VIII are at 50 and 100mil diameter. It's just simple math anyone (I would assume) can do to determine at what intervals the hash marks are (5mil) and that the bottom hash mark is at a radius of 75mil (150mil diameter). And that picture IS significant evidence because it's an actual gunsight, in an actual plane, showing that 150mil mark.

And didn't we establish there's a difference between the full sight picture vs. the MECHANICAL sight picture? All I'm saying is to further increase the FULL sight picture, and let the mechanical sight picture take care of the rest like apparently is already going to happen.

Well the sight bitmap will still be 256x256 max. The sight bitmap will be 128 Mils across, however there may be some sights that are mechanically smaller, so they will not show the full 128 Mil bitmap as I understand it.

[Baumer]

Well you carry on then, since you know best how to get HTC to make changes.

Do you know what specific model of MkVIII that is? Do you know specifically what plane it was built for?

Yes the math is easy to do now that it's been thoroughly discussed, but that doesn't mean that HTC doesn't need more documentation for the specific implementation.

I have no idea if HTC will increase the sight for you or not, but I do know what is typically needed to show HTC that there's an issue that needs to be addressed. All I'm saying is that the image you provided is less documentation than I think they will need.

But good luck anyways,
Baumer

[BulletVI]

Boumer would this help ????

Its some gun sight data i found bud 


http://www.tarrif.net/cgi/production/all_gunsights_adv.php

[Baumer]

That's an interesting website I haven't see thanks Bullet. However I think it is a reference for tank and artillery sights, not aircraft sights but cool none the less.

[BulletVI]

Ok i keep on searching then

[Saxman]

The point is if one sight is demonstrably larger than 128mil, (regardless of model, it's clear that there WAS a Mk.VIII sight that extended to 150mil) there might be others that were as well (IE, I think the Japanese Type 98 had a ring at 150-200mil. I'm trying to find the information on that one).

[TequilaChaser]

That's an interesting website I haven't see thanks Bullet. However I think it is a reference for tank and artillery sights, not aircraft sights but cool none the less.

As Baumer posted, Thanks Bullet, for that weblink

the below weblink , I like even better

http://www.tarrif.net/wwii/d_and_d.htm

is from the same website, but shows sources & statistics from all countrys

fighters, attack aircraft, bombers, artillery, Ground Vehicles, Warships, etc....

Information Source List for all data on this website:

http://www.tarrif.net/cgi/production/all_sources_adv.php

Thanks again  Bullet