F/A-16. A CAS aircraft with some get up and go.

[Abraham Gubler]

What was Gen. Larry Welch's response at the time to concerns about a loss of BOT CAS capability with the retirement of the A-10?

300 A-16s.

 

[RyanC]

Little problem against someone with only 12.7mm HMGs and SA-7s as in VietNam, ODS, OIF and OEF but a sure death sentence up against the Soviet Army.

Actually, USAF studies in 1985 indicated that the A-10 would be survivable in mid to high intensity conflicts until the mid 1990s -- at which point newer generation SAMs or MANPADs would make things a bit iffy; along with more of the battlefield shifting to 24-hour round the clock conflict -- requiring more all-weather capability.

 

[Abraham Gubler]

I think you're getting Phase I (Boyd inspired Vietnam turboprop stuff) A-X that existed before June 1967 mixed up with post June 1967 Phase II (ETO heavy jet CAS) A-X.

I’m not trying to argue that the A-10 and GAU-8 were not designed to have an anti armour mission but that it was added on to the existing design concept of a COIN aircraft during the development cycle. And all of these examples you raise further reinforce it.

Spec: interviews with combat pilots in current action is a far greater influence than reading a book from WWII
Gun: the original requirement was for a high velocity 30mm. For improved accuracy (5 mils vs 8 mils) and improved striking power (360g HEI vs 100g HEI).
AP: if the gun was speced originally as an anti tank weapon they would have gone for an anti tank calibre like 37-57mm. You have a problem with penetration capability when you have a pre-exsisting concept (30mm) that you now want to make it do more.

 

[Abraham Gubler]

So why did the VVS procure the Su-25, a close analogue to the YA-9A -- when faced with the same level of ground threat -- (while US GBAD was pathetic, NATO GBAD wasn't (Gepard/Roland) ) -- and the same level of air threat (roaming swarms of NATO fighters)?

Soviets do things differently especially since they were going to be the attacking ones. And their Su-25 is very different to the A-10. It has more speed and more sensors and different weapons.

 

[Triton]

Secondly, other than Iran and North Korea is there any other place the US will commit ground troops, in large numbers, that would constitute a high threat environment? The future seems to be a very large engagement with a fairly advanced enemy force or SOLIC in Africa or some such place where CAS most likely will be a Reaper or two.

Have the next two wars already planned, bobbymike? Will the United States military and coalition forces might engage in any unforeseen wars or international crises between now and 2040? Did anyone predict the NATO bombing of Yugoslavia or IFOR and KFOR? Somalia? The Crimea/Ukraine crisis?

 

[RyanC]

Gun: the original requirement was for a high velocity 30mm. For improved accuracy (5 mils vs 8 mils) and improved striking power (360g HEI vs 100g HEI).

Actually, the original A/X Requirements in the December 1966 Requirements Action Directive (as I said before) was for "capability equal to or better than four M-39 20mm guns".

It's worth noting that the Vought V-502 series of proposals for A/X back when it was Phase I were all armed with a 20mm M61 with 1,500 rounds -- meeting the "greater than 4 x M39 Cannon" requirement -- you can find them on this board; here:

http://www.secretprojects.co.uk/forum/index.php/topic,2615.0/all.html

AP: if the gun was speced originally as an anti tank weapon they would have gone for an anti tank calibre like 37-57mm. You have a problem with penetration capability when you have a pre-exsisting concept (30mm) that you now want to make it do more.

Extremely large caliber weapons (37x263 [BK 3.7]) weren't feasible with the technologies of the time or envisioned, due to low rates of fire and low ammunition stowage.

If we were doing "big gun on aircraft" again; extremely large caliber weapons would be feasible, thanks to much better computer assisted targeting (like that on Eurofighter).

As it is, the 30x173 round the GAU-8 uses is pretty big compared to other aircraft armament -- in some ways comparable to the 37x155 the N-37 fired.

PS -- The USAF's Armament Laboratory in 1967-68 proposed two armaments for the A-X:

Option I: M61 scaled up to fire the US Army's 30x100B WECOM round at 2,000~ fps and 6,000 RPM

Option II: 25mm weapon fired at 4,000 fps. This was eliminated because it would have delivered a fully developed gun by 1972; two years after the then-demanded 1970 IOC of A/X.

The 30x100B WECOM round is significantly smaller than the 30x173; you can find photos of them on Anthony William's site.

Other investigated concepts later were using the Army's Bushmaster VRFW-S (abandoned when they couldn't solve the "turbine engine ingests discarded sabot" problem).

In one study, a contractor proposed a 57mm recoilless rifle (!) for armament (all the other contractors in that study recommended a 30mm gun).

 

[RyanC]

And their Su-25 is very different to the A-10. It has more speed and more sensors and different weapons.

The A-9 had the same speed advantage over the A-10 that the Su-25 has (100 MPH) -- with modern AA weapons, 100 MPH isn't as noticeably useful as it was in WWII in avoiding ground fire.

As for sensors and different weapons -- the two aircraft (A-10/Su-25) have closely paralleled each other in sensors and weapons fits -- very basic initial sensors and weapons; followed by modernization in the 2000s.

 

[Abraham Gubler]

Actually, the original A/X Requirements in the December 1966 Requirements Action Directive (as I said before) was for "capability equal to or better than four M-39 20mm guns".

I was referring to the later spec as the context of the discussion (at that time) was why did the A-10 have the GAU-8.

Extremely large caliber weapons (37x263 [BK 3.7]) weren't feasible with the technologies of the time or envisioned, due to low rates of fire and low ammunition stowage.

They were extremely feasible because they were off the shelf (personally I would probably select a 35mm or 40mm L70 gun). If you were actually required under the 69 A-X spec to build an anti tank aircraft then you wouldn’t fit a very large 30mm cannon with high rate of fire. If you decided a gun was needed to engage tanks, or were required to have a gun, then for starters a radar or laser would be fitted to provide all important ranging data. And a gun that can actually defeat the target. You wouldn’t need the high rate of fire and deep magazine because you could hit and kill the target with far less number of rounds.

 

[Abraham Gubler]

As for sensors and different weapons -- the two aircraft (A-10/Su-25) have closely paralleled each other in sensors and weapons fits -- very basic initial sensors and weapons; followed by modernization in the 2000s.

Ahh no. The Su-25 flew from the start with a laser rangefinder, target designator. The A-10 attack system was all gunsight and pilot head until recently.

 

[Avimimus]

So why did the VVS procure the Su-25, a close analogue to the YA-9A -- when faced with the same level of ground threat -- (while US GBAD was pathetic, NATO GBAD wasn't (Gepard/Roland) ) -- and the same level of air threat (roaming swarms of NATO fighters)?

Soviets do things differently especially since they were going to be the attacking ones. And their Su-25 is very different to the A-10. It has more speed and more sensors and different weapons.

Ah - more speed and much more maneuverability at speed (The A-10's degrees per second turn rate drops off quickly as speed increases - the Su-25 is able to maintain its maximum turn rate at high-subsonic speeds and reasonable weapon loads - the turn profiles are almost completely different). A good observation indeed.

That said, it is worth adding the clarification - the improved sensors appear in the later anti-tank versions (and night-time anti-tank versions). The original Su-25 just had the Mk.1 eyeball and a bunch of dials/lights.

It is worth noting that the Su-25 was procured in fairly small numbers. I suspect it was always seen as a specialised close-support platform for medium-to-low intensity environments - with the ability to use it in higher threat environments only with greater casualties.

 

[Avimimus]

If we were doing "big gun on aircraft" again; extremely large caliber weapons would be feasible, thanks to much better computer assisted targeting (like that on Eurofighter).

Ah, I've been quietly stewing on this all day. A 40mm Bofors derivative could get a fair degree of accuracy out to 6km. If it could be elevated it could fire beyond the range of even modern SHORAD.

Modern fire-control would make accurate laying of fire possible. A semi-rigid mount firing in semi-automatic mode (200 rpm) could provide adequate off-boresight/wind-correction without excessive recoil.

Modern bursting munitions would be effective against infantry, the 115 gram high explosive charge would be effective against light earthworks and soft targets, armour penetrating rounds would be powerful enough to take out IFV or cripple tanks at medium ranges (5km).

It would be easy to carry a couple hundred rounds and fire above MANPADs and the range of 23mm-30mm anti-aircraft weapons. Even legacy SAMs could be engaged, provided their effective range was less than five kilometers.

It certainly is an interesting idea to design an aircraft around.

 

[Abraham Gubler]

That said, it is worth adding the clarification - the improved sensors appear in the later anti-tank versions (and night-time anti-tank versions). The original Su-25 just had the Mk.1 eyeball and a bunch of dials/lights.

Nope they came with the laser rangefinder bombing system and laser target designator (AS-10, AS-14 missiles) from the start. These are important capability differences compared to the A-10 enabling bombing in a much more survivable profile and of course the guided missile capability with far quicker target acquisition than the add on Maverick. It’s that little window in the bottom part of the nose of the Su-25 makes for all the difference.

 

[Abraham Gubler]

Ah, I've been quietly stewing on this all day. A 40mm Bofors derivative could get a fair degree of accuracy out to 6km. If it could be elevated it could fire beyond the range of even modern SHORAD.

Dispersion at these ranges is going to be so high (your 80% circle is going to have a diameter of 150m at 6km for a 2mrad weapon) that you’re not going to directly hit anything (which you need to get an AP round into a vehicle). But the advantage of the bigger, more accurate guns is you need less rounds to guarantee a hit against a typical AFV at typical combat ranges.

Narrowing it down a bit if you were in 1969 going to replace the GAU-8 development with a dedicated anti-tank weapon development I would think a lightweight 35x228mm gun (like the ARES Talon or Bushmaster III) would be a good development. It would fit roughly into the weight and volume of the GAU-8 gun and magazine and enable two magazines of around 250-300 rounds each (different ammunition natures with twin feeds enabling round selectable bursts).

Firing a two second burst 18 rounds from 550 rpm) would put 14 into a 3m diameter circle at 1,200m range (2 mrad 35mm gun). Firing APDS ammunition that would perforate over 120mm of RHA at this range would be extremely lethal. And thanks to the twin feed you can select the other magazine and shoot 100% HEI at soft targets. And have enough ammo for 16 two second bursts of each type (APDS & HEI).

You’re not going to have as good a supressing fire front gun to keep the trigger down while you swoop in to drop napalm and anti pers bombs against the VC but you would have a much better gun for rolling in on tanks from low altitude attacks.

 

[RyanC]

Ahh no. The Su-25 flew from the start with a laser rangefinder, target designator. The A-10 attack system was all gunsight and pilot head until recently.

They've had an integral laser receiver from the start; meaning all sorts of people can designate targets for an A-10 to kill with LGBs. Maverick has also been part of the A-10's loadout from the beginning (first E/O; then IIR); so there was a limited smart strike capability.

What's interesting is that one of the reasons the A-10B was killed was because the USAF planned on giving the A-10 community 100~ LANTIRN pods in the mid 1980s as they viewed the one-man LANTIRN as more desirable than the two-man A-10B N/AW. In the end, the A-10 force never got LANTIRN.


EDIT: Actually, it took until about Operation Enduring Freedom for the A-10 fleet to begin getting LANTIRN.

 

[Abraham Gubler]

They've had an integral laser receiver from the start; meaning all sorts of people can designate targets for an A-10 to kill with LGBs. Maverick has also been part of the A-10's loadout from the beginning (first E/O; then IIR); so there was a limited smart strike capability.

Pave Penny just tells you where someone else is pointing a laser. It can’t be used to provide a target solution to a bombing computer or to designate a weapon.

Maverick has also been part of the A-10's loadout from the beginning (first E/O; then IIR); so there was a limited smart strike capability.

Maverick requires a lot more effort from the pilot to find and select the target than a laser guided weapon. You can only use the HUD sight for a rough point and then need to check the video camera feed to make sure you’ve actually got the target selected. The SAL weapon system used on the Su-25 enable the pilot to put the sight into the target and then fire the weapon. He has to keep it there for the time of flight but the AS-10 is 50% faster than the Maverick to compensate for this problem. Still easier target acquisition is better than slightly harder target guiding.

 

[RyanC]

Pave Penny just tells you where someone else is pointing a laser. It can’t be used to provide a target solution to a bombing computer or to designate a weapon.

AFAIK on the A-10; PP locational data is integrated into the HUD via bounding box draw -- so you can use it to bomb/strafe someone via on board weapons as long as the lasee is lasing it for you.

Regarding self-lasing; I think the Su-25 gained the same targeting capability as the MiG-23M because there wasn't as much doctrinal opposition within the VVS to a dedicated ground attack aircraft as there was in the USAF; and with much less opposition, it was easier to slightly blur the lines to also include light precision strike in the Su-25's repertoire -- it makes me wonder how long the Sturmoviki cadre lasted in the VVS post-war and to what positions they rose within the Soviet defense hierarchy.

 

[Hot Breath]

Ah, I've been quietly stewing on this all day. A 40mm Bofors derivative could get a fair degree of accuracy out to 6km. If it could be elevated it could fire beyond the range of even modern SHORAD.

Dispersion at these ranges is going to be so high (your 80% circle is going to have a diameter of 150m at 6km for a 2mrad weapon) that you’re not going to directly hit anything (which you need to get an AP round into a vehicle). But the advantage of the bigger, more accurate guns is you need less rounds to guarantee a hit against a typical AFV at typical combat ranges.

Are you suggesting A-10s shoot at targets at 6,000 metres range with their guns? That would be extraordinary shooting indeed to hit anything, including an AFV at that range.

Narrowing it down a bit if you were in 1969 going to replace the GAU-8 development with a dedicated anti-tank weapon development I would think a lightweight 35x228mm gun (like the ARES Talon or Bushmaster III) would be a good development. It would fit roughly into the weight and volume of the GAU-8 gun and magazine and enable two magazines of around 250-300 rounds each (different ammunition natures with twin feeds enabling round selectable bursts).

Firing a two second burst 18 rounds from 550 rpm) would put 14 into a 3m diameter circle at 1,200m range (2 mrad 35mm gun). Firing APDS ammunition that would perforate over 120mm of RHA at this range would be extremely lethal. And thanks to the twin feed you can select the other magazine and shoot 100% HEI at soft targets. And have enough ammo for 16 two second bursts of each type (APDS & HEI).

You’re not going to have as good a supressing fire front gun to keep the trigger down while you swoop in to drop napalm and anti pers bombs against the VC but you would have a much better gun for rolling in on tanks from low altitude attacks.

Didn't the USAF at one stage trial the French DEFA cannon as an alternative to the GAU-8 and found it more accurate? I seem to remember reading that somewhere in an old magazine several years ago.

 

[RyanC]

Relevant to this discussion:

http://www.dtic.mil/get-tr-doc/pdf?AD=ADA018749

1975 US Army evaluation of autocannon concepts from 20mm to 40mm for attack helicopters.

Concepts studied were:

M39/M24 clone: 20mm, 750 RPM, 3300 fps
0.56 lb round; 1540 grain projectile
5.41 to 5.31 mil deviation

XM230 clone: 30mm, 600 rpm, 2200 fps
0.67 lb round; 3031 grain projectile
5.25 to 5.19 mil deviation

Advanced Automatic Cannon I: 30mm, 450 rpm, 4000 fps
1.33 lb round; 5180 grain projectile
5 to 2 mil deviation

Advanced Automatic Cannon II: 40mm, 450 rpm, 2950 fps
2.2 lb round; 7210 grain projectile
5.21 to 5.14 mil deviation


EDIT: Also Revelant:

http://www.dtic.mil/get-tr-doc/pdf?AD=ADA140367

Historical Development Summary of Automatic Cannon Caliber Ammunition: 20-30 Millimeter

Has a great thing on hardcopy page 7 regarding 25mm ammo:

"This author soon reached the conclusion that the requirement [for Vehicle Rapid Fire Weapon System (VRFWS)] was written specifically and solely so that the HS820 could not satisfy it. By making that assertion he almost started a fight at a joint service meeting at Rock Island some years ago, but the Army could not give a better explanation then nor have they yet."


EDIT II:

hardcopy page 24 is when they talk about GAU-8 30mm:

"Also, the simple "optimization" expedient of selecting the smallest round that would defeat the hardest target had been used."

 

[sferrin]

If we were doing "big gun on aircraft" again; extremely large caliber weapons would be feasible, thanks to much better computer assisted targeting (like that on Eurofighter).

Is that system anything like the USAF tested?

(Starting at 6:12)

Today's Technology - 1984 AFSC STAFF FILM REPORT
https://www.youtube.com/watch?v=LouqEIBLTzU

 

[Abraham Gubler]

Are you suggesting A-10s shoot at targets at 6,000 metres range with their guns? That would be extraordinary shooting indeed to hit anything, including an AFV at that range.

He was referring to using a 40mm gun at 6km range. The GAU-8 at 6km would have an 80% circle with a diameter of 240m. With a 100 round burst that would leave around 20m between each shell hit (with an even dispersion).

 

[Abraham Gubler]

AFAIK on the A-10; PP locational data is integrated into the HUD via bounding box draw -- so you can use it to bomb/strafe someone via on board weapons as long as the lasee is lasing it for you.

Pave Penny just provides target indication via the HUD. It doesn’t provide any information into a bombing computer. The laser on the Su-25 like the lasers (or radars) on many other aircraft provide ranging data as well as target indication enabling the pilot and bombing computer to quickly and accurately release the bombs. The pilot of an A-10 just has the HUD working as a gunsight to release the bombs requiring a lot more time and effort to drop them with far less accuracy.

 

[Avimimus]

That said, it is worth adding the clarification - the improved sensors appear in the later anti-tank versions (and night-time anti-tank versions). The original Su-25 just had the Mk.1 eyeball and a bunch of dials/lights.

Nope they came with the laser rangefinder bombing system and laser target designator (AS-10, AS-14 missiles) from the start. These are important capability differences compared to the A-10 enabling bombing in a much more survivable profile and of course the guided missile capability with far quicker target acquisition than the add on Maverick. It’s that little window in the bottom part of the nose of the Su-25 makes for all the difference.

Very true. I'd been thinking about acquisition sensors as opposed to rangers and designators when I wrote that.

I should also say that I'd always assumed the bombsight for the A-10a had a laser ranger, rather than just a ballisitic computer. So, I'm clearly a bit clueless sometimes. Thanks for the insight.

 

[Avimimus]

1975 US Army evaluation of autocannon concepts from 20mm to 40mm for attack helicopters.

This - and the plans for a 45mm smoothbore in the Su-25 are what got me thinking larger calibers. Still, for the employment I was considering, the 30mm advanced autocannon I is superior.

Ah, I've been quietly stewing on this all day. A 40mm Bofors derivative could get a fair degree of accuracy out to 6km. If it could be elevated it could fire beyond the range of even modern SHORAD.

Dispersion at these ranges is going to be so high (your 80% circle is going to have a diameter of 150m at 6km for a 2mrad weapon) that you’re not going to directly hit anything (which you need to get an AP round into a vehicle). But the advantage of the bigger, more accurate guns is you need less rounds to guarantee a hit against a typical AFV at typical combat ranges.

If those dispersion figures can't be improved (and they seem fairly optimistic) - it works out to about 900 rounds expended for a direct hit on a BMP-1 and 700 to hit a T-72. So, three minutes of firing and close to a ton of ammunition! Not practical, although the 35mm caliber might do a little better.

Of course, guided rounds now exist which could compensate. But, then again, 8km air-defense missiles also exist now. The penetrating power of a corrected round is a bit uncertain in any case. At such ranges the ability to design an effective guidance system which can fit into a bullet is also a problem. Still I wonder how effective it could be with guided rounds fired at a 45 degree upward angle (12 km range)?

 

[RyanC]

The pilot of an A-10 just has the HUD working as a gunsight to release the bombs requiring a lot more time and effort to drop them with far less accuracy.

A-10A has CCIP, so it's not all by pure eyeball -- supposedly the radar altimeter is used to get the data required for the bombsight -- but not as good as a dedicated A/G radar like A-7D feeding information to the system, which makes sense; as one of the major drivers of A/X was to be equal or lower-cost than A-7D.

 

[Abraham Gubler]

A-10A has CCIP, so it's not all by pure eyeball -- supposedly the radar altimeter is used to get the data required for the bombsight -- but not as good as a dedicated A/G radar like A-7D feeding information to the system, which makes sense; as one of the major drivers of A/X was to be equal or lower-cost than A-7D.

Well that makes a lot of sense. Thought it was a bit stupid to build a plane without CCIP so it can't do a pop up bomb run. But without a measuring device to provide range to the target accuracy is going to be poor.

 

[RyanC]

Out of curiosity; how do you calculate dispersion from given data like "Dispersion 5 milliradians diameter, 80 percent circle", for a given range, Abraham?

I've tried googling for the formulas; but can't easily find them. :'(

 

[Abraham Gubler]

The 80 percent circle is the measure. A circle in which 80 percent of rounds will land.

A circle with a radius of 1,000m has a circumference that can be measured in milliradians (mrad) which is precisely 2 x pi x 1,000 (or 6283.185 mrad in a circle). But it is easily converted to an approximation with angular mils of 6,400 per circle. This is a very common measure used in the military in place of circular degrees to calculate angles because it enables you to easily calculate the deviation over range. As an angular deviation of 1 mrad over 1,000m equates to a point 1m away from the boresight.

So a 5 mrad deviation 1.2 km away (GAU-8 dispersion in mrad at combat range) is 6m. Apply this to a cricle 1.2 km away and it has a radius of 6m, or diameter of 12m.

 

[RyanC]

I believe the current state of the art for A/A gun guidance systems is the Eurofighter's 27mm BK installation.

AFAIK, the pilot 'locks on' to the enemy aircraft with the radar -- the system then begins tracking everything -- doppler radar input on enemy aircraft motions; and probably own aircraft motions from the INS/GPS system; and you merely have to move the aircraft into a position where the system sees a valid gun trajectory that intersects the target (e.g. pipper onto target); and the gun fires automatically in a restricted burst with no human interaction required.

I wonder what the equivalent system for a ground attack aircraft would be.

You'd need some sort of wide area rapid scan IR system that can scan a sector in front of the aircraft's nose several times a second to identify possible ground attack targets -- one of the early requirements for LITENING was for it to automatically classify and sort targets by type: (Truck, Wheeled APC, Tank); but that was deleted. We can probably do that now with much better computing power.

Then some way of painting all possible tank threats found by this wide area scanner onto the pilot's HUD as bounding boxes for situational awareness; along with a close up EO/IR system slaved to a laser range finder that's slewed on target by the rapid scan IR system to feed detailed targeting information to the ballistics computer for the gun run.

 

[sferrin]

I believe the current state of the art for A/A gun guidance systems is the Eurofighter's 27mm BK installation.

AFAIK, the pilot 'locks on' to the enemy aircraft with the radar -- the system then begins tracking everything -- doppler radar input on enemy aircraft motions; and probably own aircraft motions from the INS/GPS system; and you merely have to move the aircraft into a position where the system sees a valid gun trajectory that intersects the target (e.g. pipper onto target); and the gun fires automatically in a restricted burst with no human interaction required.

This is essentially the system they tested in the F-15 back in the 80's in the video I posted on the previous page. There was a guy on F-16.net who happened to be an engineer involved. According to him, even though the results were excellent the pilots were skeptical of giving up control of the aircraft at a crucial moment.

 

[Sundog]

Don't modern Russian aircraft use a similar system as well? IIRC, I read a report about the MiG-29 that stated it had the same kind of sytem.

 

[Jeb]

Source:
http://intercepts.defensenews.com/2014/04/dr-evil-weighs-in-on-usaf-a-10-debate/

I saw this graphic before and I think whoever created it has *ahem* misrepresented the debate. The F-15C was never tasked as multirole. It's always been pure air superiority. The F-15E is entirely multirole and not only that, it can fly all of those A-10 missions and more.

 

[Triton]

Source:
http://intercepts.defensenews.com/2014/04/dr-evil-weighs-in-on-usaf-a-10-debate/

I saw this graphic before and I think whoever created it has *ahem* misrepresented the debate. The F-15C was never tasked as multirole. It's always been pure air superiority. The F-15E is entirely multirole and not only that, it can fly all of those A-10 missions and more.

I added the cartoon for discussion purposes. I understand from the Defense News article that the cartoon has been circulating throughout the defense community.

 

[Avimimus]

I believe the current state of the art for A/A gun guidance systems is the Eurofighter's 27mm BK installation.

AFAIK, the pilot 'locks on' to the enemy aircraft with the radar -- the system then begins tracking everything -- doppler radar input on enemy aircraft motions; and probably own aircraft motions from the INS/GPS system; and you merely have to move the aircraft into a position where the system sees a valid gun trajectory that intersects the target (e.g. pipper onto target); and the gun fires automatically in a restricted burst with no human interaction required.

This is essentially the system they tested in the F-15 back in the 80's in the video I posted on the previous page. There was a guy on F-16.net who happened to be an engineer involved. According to him, even though the results were excellent the pilots were skeptical of giving up control of the aircraft at a crucial moment.

Don't modern Russian aircraft use a similar system as well? IIRC, I read a report about the MiG-29 that stated it had the same kind of sytem.

The Russian gunsights can use radar or EO/IR & laser range-finding. I remember reading a quote to the effect that the gun designers would've only given the GSh-301 a 75 round magazine if they knew it would be that effective.

However, I haven't heard of any Russian aircraft using an automatic firing system (as used by the Eurofighter - I recall that the EF once shot down a target while on autopilot - but that could be just a rumour).

I wonder what the equivalent system for a ground attack aircraft would be.

I like your fancy system (as it could enhance situational awareness).

A simpler approach is already in service of course. Most Russian ground attack aircraft can use EO sensors to identify and acquire a target. A laser range finder is applied to it and feeds into a ballistic computer. Two circles appear on the HUD - one the target, the other the gunsight. The pilot lines up both circles and when one disappears behind the other the pilot fires.

With the SPPU depressible gunpods the system can automatically deflect the guns as the pilot flies overhead.

 

[Avimimus]

By the way - does anyone have a guess about what the minimum dispersion you can get with semi-automatic a 40mm rigid mounted gun is?

I'm curious about the differences between recoil/vibration related dispersion and pure aeroballistic dispersion in a round of that size.

 

[bobbymike]

By the way - does anyone have a guess about what the minimum dispersion you can get with semi-automatic a 40mm rigid mounted gun is?

I'm curious about the differences between recoil/vibration related dispersion and pure aeroballistic dispersion in a round of that size.

Not to stray off topic but watching gun footage from hovering or slowly moving Apaches firing the 30mm chain gun they seem to have a lot of dispersion (as compared to where the reticle is pointing) is this also a product of recoil/vibration round size issues?

 

[Hot Breath]

By the way - does anyone have a guess about what the minimum dispersion you can get with semi-automatic a 40mm rigid mounted gun is?

I'm curious about the differences between recoil/vibration related dispersion and pure aeroballistic dispersion in a round of that size.

Not to stray off topic but watching gun footage from hovering or slowly moving Apaches firing the 30mm chain gun they seem to have a lot of dispersion (as compared to where the reticle is pointing) is this also a product of recoil/vibration round size issues?

More than likely also a problem with the mounting. Rotating turrets on aircraft which themselves are subject to a lot of vibration unless gyro-stabilised are going to be inherently less accurate. Remember, for "every action there is an equal reaction"? The helicopter is hanging from the shaft of it's rotors, the gun fires, it will exert thrust and the helicopter will tilt, when the pilot attempts to compensate, he'll over-compensate and the gun will be swinging back and forth.

 

[Hot Breath]

Are you suggesting A-10s shoot at targets at 6,000 metres range with their guns? That would be extraordinary shooting indeed to hit anything, including an AFV at that range.

He was referring to using a 40mm gun at 6km range. The GAU-8 at 6km would have an 80% circle with a diameter of 240m. With a 100 round burst that would leave around 20m between each shell hit (with an even dispersion).

Thank you, that is a lot clearer now.

 

[Abraham Gubler]

The M230 gun on the Apache is actually pretty accurate (3 mrad dispersion) for an aerial gun. Its just that you are seeing it shoot on the gun camera footage at a small target (a person) and it fires small bursts (10 rounds per second) from long distances (1-2km typical). That being said the Denel Rooivalk flies with a 20x139mm gun which will outshoot the M230 for accuracy by a long margin.

 

[quellish]

This is essentially the system they tested in the F-15 back in the 80's in the video I posted on the previous page. There was a guy on F-16.net who happened to be an engineer involved. According to him, even though the results were excellent the pilots were skeptical of giving up control of the aircraft at a crucial moment.

AFTI Phase 1 included something similar (same program?) tested on the F-15 and later the AFTI/CCV F-16:
http://www.dtic.mil/dtic/tr/fulltext/u2/a166724.pdf
"Even with its limited application of control configured
vehicle technology, the AFTI/F-15 was highly successful in adding to the advanced fighter technology base. By changing the control
laws in its control augmentation system, adding an ATLIS-II electro-optical target tracker pod (78:169), and adding a spec-ial
interface unit to tie the flight and fire control systems together, the AFTI/F-15 achieved a slight control surface
decoupling (96:26; 78:169).
the AFTI/F-15 automatically fine-tuned the fire control cues and deooupled flight control surfaces
(i.e., made them work independently), then limited maneuvers to
plus or minus 1 G during the final seconds of weapons delivery or
gun firing (96:26). This arrangement allowed air-to-air gunnery,
strafing, and bombing from unusual flight profiles (78:170). In August 1982 the AFTI/F-15 completely destroyed with a two second
burst a maneuvering PGM-102 drone in a most difficult gun firing condition (78:169-170; 96:26). (The PQM-102 was flying at 420 Knots, in a 4 G right turn into its attacker, while the AFTI/F-15 was in a 3.3 G right turn at 400 Knots, for a 130 degree aspect attack at 1.7 Kilometers (78:169).) The new integrated fire and flight control system also allowed a spiral strafing run, rather
than the usual straight pass at the target. This promised to give greater survivability against linear-predictor anti-aircraft
artillery (78:170). And in late 1982 the AFTI/F-15 accurately dropped bombs while performing 3.5 G maneuvers from ran5es of 1200
[/size]to 5200 meters; it had the same accuracy as a normal F-15 in wings-level approaches (78:170)."

 

[pathology_doc]

According to him, even though the results were excellent the pilots were skeptical of giving up control of the aircraft at a crucial moment.

How does this compare to or differ from the auto-attack systems on aircraft like the F-106, which were in their final form supposed to do almost everything short of managing take off and landing? (Sort of eerie, that - I can imagine F-106's flying around, their pilots already dying of radiation poisoning, what's left of the SAGE system faithfully flying them to an intercept and pulling the trigger for them... )