schnuersi said:

Oh god no! You mixed up range with ceiling. The AA ceiling for the 3" is ~4000 with full caliber shell. The AA ceiling for the 57mm L70 is usually given as 5000 m with full caliber shells. Which is a bit optimisitic IMHO but its consitent with the advantage in MV the 57/70 has over the 3". Because this is what matters most for AA ceiling for guns of shell weights measured in the kg range. Muzzel velocity. If the shells start faster they climb higher. ME plays a role too but effective ceiling does not scale linear with ME. There is apoint of dimishing returns that is reached ~5".

According to Tony the AA celing of the 57/70 is 24,930 feet (7,600 m) in proximity fuze mode

http://www.navweaps.com/Weapons/WNSweden_57-70_mk123.php

Also Tony: 76/62 AA ceiling 13,200 feet (4,000 m), so there he agrees with you. 

But it looks like developing a SPAAG based on the 57/70 might be useful (stick that flapanel X-Band radar on it too)

I am also wondering whether adding a second stage to StarStreak might be useful.

graylion said:

According to Tony the AA celing of the 57/70 is 24,930 feet (7,600 m) in proximity fuze mode

http://www.navweaps.com/Weapons/WNSweden_57-70_mk123.php

Also Tony: 76/62 AA ceiling 13,200 feet (4,000 m), so there he agrees with you. 

The is because the stats for ceiling are usually not given in detail. There usually is a huge difference in max ceiling, maximung height balistically possible when shooting at full elevation, and effective ceiling. The latter one factoring the time of ascend to a point where its possible to actually get the shell close enough to the target to be effective. The shells of AA guns get extremly suceptible to wind drift in the last third of their max ceiling because of ther ever slowing speed and long exposure time. Making it allmost impossible to predict where the shell will go even with modern FCS.
The 7600 m ceiling for the 57/70 is the max ceiling or effective slant range wich is something different again. 7600 m effective ceiling for a 2,4 kg shell with a MV of 1025 m is simply unbeleivable. Even with modern FCS and proxy fuse. Its in the effective AA ceiling or slant range ranges of 120 mm or 5" guns. Post war 120 mm or 5" guns of roughly the same age. Sorry but that gets my BS sense tingling.

The 4000 m for the 3" is the effective ceiling. At this height to which the weapon will actually hit if the FCS is up for the task.

Data on maximum ceiling effective ceiling and effective AA envelope is usually not presented in detail.

The fire controll involved also plays a role but this has mostly affected smaller guns and increased their effective range. Lager guns have been used at the limit of what is balisitical possible in the past. The difference over time there is fewer guns and higher rate of fire increasing the effective AA envelope but not or allmost not the effective ceiling.

Reading a bit - MAD-FIRES might help here.

graylion said:

Reading a bit - MAD-FIRES might help here.

Sure things change if diffent types of ammo are used. Sub caliber alone usually results in higher ceiling, effective and max, compare to full caliber shells.

Guidance, proximity fuse or pre programmed air burst and optimised fragmentation patterns also improve performance.

There are limits to what can be achieved though. At some point the shell gets so slow it will become a problem to hit a moving target with these new features as well.
As mentioned the question what the most optimal system is depends on the exact parameters. Which includes things like vehicle seize and weight and logistics. How many shots are fired in a typical operational cycle. How large and heavy is the ammo etc.
The thing is if a weapon system like Dracon or another 3" SPAA design is intended as all round solution that also will engage smaller drones at lower altitudes you could end up with a system that is overkill for most targets while being at the limit of its capability for some others. The target mix plays a major role for the evaluating of this.
As educated guess I would say that a gun missile combination might be the most efficient. A gun in the 34-40 mm range for most targets and the missile with more range, ceiling and idividual striking power for the targets that the gun is ineffective against. Assuming the former type of targets makes up the majority.

So, something like Skyranger 30 and take something like Mistral or StarStreak and give it a more powerful first stage to give it a higher ceiling? That's probably easier than developing a new missile from scratch.

On my datapages, max ceiling is basically the altitude reached when the gun is at it's maximum elevation.  So, if a drone was at that altitude, it could only be engaged for a few seconds until it flew past that point.  However, this neglects whether the FCS can even engage a target at this altitude and also the time of flight of the projectile.  The chart below is rather dated, as it is for a UK naval gun of the WWII era, but it does show both the ballistic performance of the gun along with the capabilities of the FCS that controlled it in the AA mode, the HACS.

As you can see, this gun had a max elevation of 80 degrees and a range of about 38,000 feet at that elevation, but the HACS FCS could only engage a target at a max altitude of 30,000 feet.  The other thing to note is the time of flight (TOF) which was about 30 seconds.  Needless to say, a target would move a long distance and maneuver in half a minute, so the chances of hitting something at that altitude were minuscule.  Note that the effective range of this gun/FCS combination was for a TOF of 12 seconds or less and a max altitude of about 18,000 feet.  You really would need a similar chart to this one to be able to judge the effective range/altitude of any AA weapon/FCS combination.

This image is poor, but here is a much better image without the HACS overly.

graylion said:

So, something like Skyranger 30

As mentione I would go bigger. 35-40 mm. The system is supposed to be multi purpose and not only anit drone. I think for decent range and destructive effect against helicopters and fixed wing this class of caliber is required.

graylion said:

and take something like Mistral or StarStreak and give it a more powerful first stage to give it a higher ceiling?

StarStreak and RBS70 apparently allready have a 5000 m ceiling. That seems sufficient to me. After all the short range air defense is not alone. Its part of the AA envelope. There should be longer ranged systems covering the theatre that can engage targets behond tha hight. I don't think one system need to be able to do it all.

graylion said:

That's probably easier than developing a new missile from scratch.

Propably yes.
It likely that an upgraded version of StarStreak and RBS70 can reach 6 km ceiling if so desired without massive redesign.

Great charts!

They pretty much show what I tried to put into words.
To get the effective range against a specific target the TOF is the limiting factor.
For a single, small point target like a recon drone the TOF limit will be in the 10 to 15 seconds range at best without guided projectiles. At this length of TOF the drone operate still can actively evade regardless of lag. In this chart 15 seconds is still below 8000 m. Five seconds is still below 3000 m. The RN concidered 12 seconds TOF to be the limit. Which seems very reasonable. Even for today.
I think its pretty ovious why 7600 m effective AA ceiling for a 57/70 even when using prox fuse is very optimistic.
It also becomes obvious why sub caliber like FAPDS is a good idea for AA purposes.

The 35mm Millennium system is said to be able to engage Fighter aircraft/attack helicopters at 3,500 m ("Keep-out range").  It could probably handle a slow-moving target like a drone out a bit further.

http://www.navweaps.com/Weapons/WNGER_35mm-1000_Millennium.php#Range

schnuersi said:

graylion said: So, something like Skyranger 30 As mentione I would go bigger. 35-40 mm. The system is supposed to be multi purpose and not only anit drone. I think for decent range and destructive effect against helicopters and fixed wing this class of caliber is required. graylion said: and take something like Mistral or StarStreak and give it a more powerful first stage to give it a higher ceiling? StarStreak and RBS70 apparently allready have a 5000 m ceiling. That seems sufficient to me. After all the short range air defense is not alone. Its part of the AA envelope. There should be longer ranged systems covering the theatre that can engage targets behond tha hight. I don't think one system need to be able to do it all. graylion said: That's probably easier than developing a new missile from scratch. Propably yes. It likely that an upgraded version of StarStreak and RBS70 can reach 6 km ceiling if so desired without massive redesign.

So, talk to Thales and get an integrated system with 40mm CTA and 8 missile launchers that can take StarStreak (and possibly Martlet). That turret would probably weigh more than 2.5t, but should fit on most wheeled and tracked APV/IFV chassis?