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Am I seeing this? F-16 gun drop compared to F-18


gavagai

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Both of these pics are ~400 knots and 4g.  In both pics I hold the trigger long enough for the tracers to disappear.  I thought these two aircraft had the same gun, or am I seeing things?  With the F-16 the tracers are noticeably more spaced out and fall below the HUD.

Are the tracer types different, one with longer burn?  Different ratio of tracers?

I thought these two aircraft had the same gun but my subjective impression was that I don't have to pull nearly as much lead with the F-18, which made me wonder... If I knew nothing about these aircraft I would have assumed the F-16 cannon had a lower muzzle velocity, or fired a different type of shell with different ballistic properties.

Appreciate it if someone can explain.

tracerdrop.png

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Lots of things could be different - tracer composition as you said, but also seating position and viewing angle for instance. On top of that, the ADL is not necessarily the same. For example, the guns on the F5 are (very) slightly canted upwards, while that would not have been the case e.g. with the F-100 or F-101 (which carried the same guns, but under rather than above the nose).

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I think you cant compare it if you consider speed and Gs. Flying a 4G turn at 400 kts in the F16 and the F18 will result in different turn rates. That might cause the difference in spacing between the tracers. Try to compare this under the same turn rate between the jets. But I am just guessing here.

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19 minutes ago, darkman222 said:

I think you cant compare it if you consider speed and Gs. Flying a 4G turn at 400 kts in the F16 and the F18 will result in different turn rates. That might cause the difference in spacing between the tracers. Try to compare this under the same turn rate between the jets. But I am just guessing here.

No, the turn rates are identical. radial acceleration = v^2 / r

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^ that. For fixed G and airspeed, (instantaneous) turn rates are the same. What may differ is a) the AoA each jet requires to obtain a given G (which depends on airframe, especially wing, design) and b) whether each jet has enough power to sustain those turns or not (which is a function of available power, and required AoA to reach a desired G).

This should be obvious if you look at an EM diagram comparing two aircraft for instance.

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28 minutes ago, Mover said:

F/A-18 gun is canted up.

F-16 gun is boresighted.  

It affects strafe also.

That is fascinating.  I can't find any mention of it.  Do you know by how many degrees it is canted upward compared to the F-16?

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That sounds reasonable.  The screenshots make it look more like 10 degrees difference!

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15 minutes ago, gavagai said:

That sounds reasonable.  The screenshots make it look more like 10 degrees difference!

 

There are other factors, obviously.  What was the range?  Heading crossing angle? Aspect angle?  What's the energy state of the other aircraft?  

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1 hour ago, Mover said:

 

There are other factors, obviously.  What was the range?  Heading crossing angle? Aspect angle?  What's the energy state of the other aircraft?  

Too many variables there to give a coherent answer.  I can show you this pic though.  Both aircraft confirmed to have 1.2 degrees aoa when shooting, both with altitude hold.  It looks like the F-18 upward cant is as much as 5 degrees after subtracting aoa.

 

upward cant.png

F-18 cant.png


Edited by gavagai
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