Curious about design choice...

[ShuRugal]

Does anyone know what reasoning lead Northrop to select a pair of M-39s instead of a single M-61? The two M-39s weigh ~360 lbs, and have a combined RoF of only 3,000 rounds/min. Comparatively, a single M-61 weighs ~250 lbs, with a RoF of 6,000 rounds/min.

 

Just seems odd. With an M-61, that extra ~100 lbs saved vs 2 M-39s is over 150 rounds of ammunition, AND the M-61 will deliver more rounds on target per burst.

 

The only drawback is higher ammo consumption rate, but that can easily be managed by using shorter bursts or programming lower rates of fire for the pilot to select.

[PiedDroit]

The M-61's feed system (drum, etc) adds 300-400lbs depending on the configuration, so it's not as light as you say I think.

[Robert31178]

Plus the weight of all that extra ammo you'd be able to shoot lol, which you would now need!!

[bC3660]

Plus size of the gun.

[ESAc_matador]

Plus dispersion of the ammo. Lethal zone is higher.

[ShuRugal]

The M-61's feed system (drum, etc) adds 300-400lbs depending on the configuration, so it's not as light as you say I think.

 

According to wiki, the m-61 w/ complete feed system is 248 lbs.

 

Plus the weight of all that extra ammo you'd be able to shoot lol, which you would now need!!

 

umm, that's kind of my point? if the M-61 w/feed is 100 lbs less than 2x m-39 with feed, then that's 100lbs more ammo you can carry (~ 175 rounds of PGU-28, probably only ~150 after expanding the drum)

 

Plus size of the gun.

 

both are 1.8m long, and the radial bulk of a single M-61 is certainly less than a pair of M-39s

 

Plus dispersion of the ammo. Lethal zone is higher.

 

on the M-39? but if it is filling a larger area with fewer rounds, then the saturation is significantly lower, thus reducing the effective range of the weapon.

[Buzzles]

Hazard a guess that it's because it was designed as an export fighter, maybe?

 

Dunno on costings, but it may be that the M-39's are cheaper (even as a pair) than the M61.

 

Also, ease and cost of maintenance, ability to repair/replace parts etc... might be much easier for the M-39's, or at least, easier in places (and countries) that may not have as good infrastructure or even skilled repair/maintenance staff. The revolver cannon design is a lot more simple than the M61.

Edited November 21, 2016 by Buzzles

[Erk104]

Design limitations probably did not suite the Vulcan. The feed mechanism appears more bulky than the individual design of the M-39s. Feed system weight likely played a roll as there isn't a place more to the center of gravity that cannons will fit in the F-5.

 

These are all assumptions. The M-39s work AWESOME in my opinion. I like the way they work and really think they are excellent in both A2A as well as A2G.

[ShuRugal]

Hazard a guess that it's because it was designed as an export fighter, maybe?

 

Dunno on costings, but it may be that the M-39's are cheaper (even as a pair) than the M61.

 

Also, ease and cost of maintenance, ability to repair/replace parts etc... might be much easier for the M-39's, or at least, easier in places (and countries) that may not have as good infrastructure or even skilled repair/maintenance staff. The revolver cannon design is a lot more simple than the M61.

 

That actually makes a lot more sense. Ease of maintenance is definitely a top priority for anyone who has to import their military hardware.

[SUI - Mustang]

I worked on the swiss F-5 tigers as a weapons maintenance and mechanic when I had to do the mandatory swiss military service. We were trained to take the M-39's out of the plane completely, take them apart and clean every bit of it, put it back in and maybe replace one or another part of it when they didn't look good anymore.

But I consider myself a novice in mechanical things, and the swiss army is a militia, so we don't have professionals, we only learned that stuff during about 14 weeks. I only studied architecture before, but this was no problem for me.

Now I don't wanna even think about all the hydraulic and electrical stuff I'd have to be trained in if it was a M-61.

That might strenghten the "easy export version" argument of Buzzels above.

 

Also the M-39's are super compact and narrow and fit the tigers nose perfectly with the ammo box, when I look at the nose of a FA/18, that would never fit in there.