SRAM & cousins (missiles)

[blackshire]

Hello All,

This is a combination scale data posting -and- scale data request (for the use of all YORF members). One type of missile that has been around for some time but is relatively little-known is the quasi-ballistic (also known as semi-ballistic) missile. Because these missiles have rear-mounted fins and moderate fineness (length-to-diameter) ratios, they make good-performing and distinctive-looking scale models. As described on Wikipedia (see: http://en.wikipedia.org/wiki/Semi-ballistic ):

"A quasi-ballistic missile (also called a semi-ballistic missile) is a category of missile that has a low trajectory and/or is largely ballistic but can perform maneuvers in flight or make unexpected changes in direction and range. At a lower trajectory than a ballistic missile, a quasi-ballistic missile can maintain higher speed, thus allowing its target less time to react to the attack, at the cost of reduced range."

Perhaps the earliest quasi-ballistic missile was the Boeing AGM-69A SRAM I (Short-Range Attack Missile, see: http://www.designation-systems.net/dusrm/m-69.html ). This nuclear-armed missile was powered by a two-pulse solid propellant rocket motor which gave it a top speed of Mach 3.5 and a range of 35 to 105 statute miles (56 km - 169 km). Equipped with both an inertial navigation system and a radar altimeter, the SRAM I could fly either a terriain-following flight at low altitude (like the slower, jet-powered cruise missiles) or fly in a semi-ballistic trajectory, which included an ability to reverse its course and attack targets that were behind it (sometimes referred to as an "over-the-shoulder" launch). It was carried by B-52, FB-111, and B-1B strategic bombers. The SRAM I was in service from 1972 until 1993. The SRAM I's boat-tail gives scale models of it low drag, and the missile's narrow-diameter rocket motor exhaust nozzle (see the below-linked SRAM I photograph set) enables the motor mounts of scale SRAM I models to have high-fidelity scale appearance. Also:

In 1981, development work began on the AGM-131A SRAM II (see: http://www.astronautix.com/lvs/sram2.htm ), which was intended to arm the B-1B and B-2 strategic bombers. A tactical variant called the SRAM T was planned for carriage by the F-15E, but both versions of the SRAM II were cancelled in 1991 just before flight tests were to begin. In addition:

A current quasi-ballistic missile is the Russian 9K720 Iskander, whose NATO reporting name is SS-26 Stone (see: http://en.wikipedia.org/wiki/Iskander_missile ). It is produced by KB Mashynostroyeniya. This road-mobile theater semi-ballistic missile has a range of up to 250 miles (400 km) and cruises at Mach 6 - 7. The single-stage, solid propellant missile can carry several different types of conventional warheads: a cluster munitions warhead, a fuel-air explosive warhead, a bunker busting Earth penetrator, or an electro-magnetic pulse device for anti-radar use. The highly maneuverable Iskander can attack mobile targets, and the missile can be re-targeted in flight.

Three other quasi-ballistic (semi-ballistic) missiles are the Lockheed Martin (formerly LTV [Ling-Temco-Vought]) MGM-140A ATACMS (Army TACtical Missile System, see: http://www.designation-systems.net/dusrm/m-140.html ), the MGM-168 ATACMS (see: http://www.designation-systems.net/dusrm/m-168.html ), and the MGM-164 ATACMS II (see: http://www.designation-systems.net/dusrm/m-164.html ). These comprise a family of externally similar surface-to-surface missiles that carry varying warheads. They all have ranges of over 100 miles (160 km), except for the MGM-164, whose maximum range is 87 miles (140 km). These single-stage, solid propellant missiles have combined GPS/INS (Global Positioning System/Inertial Navigation System) guidance systems that steer them by means of movable four-fin tail assemblies that are mounted on short, tapered boat-tails. Also:

Except for the MGM-164 (which has a bi-conical nose cone), all of the ATACMS variants have ~3:1 length/diameter ratio nose cones that appear to be either secant ogives or Von Karman ogives (Haack-type nose cones). As well:

Below are links to information on the AGM-69A SRAM I, AGM-131A SRAM II, 9K720 Iskander, and ATACMS quasi-ballistic missiles. If anyone has dimensioned drawings of these missiles, they would make possible documentation for Scale models (these missiles' specifications and photographs are sufficient documentation for Sport Scale models). Here are the links:


AGM-69A SRAM I

http://www.designation-systems.net/dusrm/m-69.html (article has links to other SRAM I articles)
http://en.wikipedia.org/wiki/AGM-69_SRAM
http://www.flickr.com/photos/63014123@N02/5762591051/ (SRAM I photograph set)
http://www.astronautix.com/fam/sram.htm#more
http://www.rocketryforum.com/showthread.php?t=21784 (SRAM I semi-scale model rocket [Reply #17 has some drawings])
http://www.rocketryforum.com/showthread.php?t=23347 (SRAM I semi-scale model flight tests)
http://www.rocketryforum.com/showthread.php?t=24471 (SRAM I semi-scale model flight tests [more])
http://www.youtube.com/results?search_query=Short+Range+Attack+Missile (SRAM I videos list)


AGM-131A SRAM II

http://www.astronautix.com/lvs/sram2.htm
http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=1001
http://en.wikipedia.org/wiki/AGM-131_SRAM_II
http://www.designation-systems.net/dusrm/m-131.html
http://www.globalsecurity.org/wmd/systems/agm-131a.htm (article contains links to other SRAM II articles)


9K720 Iskander

http://en.wikipedia.org/wiki/Iskander_missile (article contains links to other Iskander articles)
http://www.astronautix.com/lvs/iskander.htm#more
http://www.military-today.com/missiles/iskander.htm
http://www.youtube.com/watch?v=EpoND183yQQ (Iskander-E video)
http://www.youtube.com/watch?v=w3F8DbZ-3yc (Iskander-M video)


ATACMS series

http://en.wikipedia.org/wiki/MGM-140_ATACMS (article has links to other MGM-140A articles)
http://www.astronautix.com/lvs/atacms.htm
http://space.skyrocket.de/doc_lau/atacms.htm
http://www.astronautix.com/lvs/atacmsii.htm
http://www.fas.org/man/dod-101/sys/land/atacms.htm
http://www.youtube.com/watch?v=Ipr_hPAcR_Q (ATACMS video)
http://www.youtube.com/watch?v=shl_4JgQAI4 (ATACMS video)


I hope this information will be helpful.

[luke strawwalker]

I picked up a spare Canuckian Arrow with the idea of converting it into a SRAM... the Rocksim stability calcs say it needs oversize fins or a lot of noseweight, since it loses the fourth fin of the V-2...

May just end up using it for a Russian version of the V-2... Korolev's R-3 (IIRC).

Later! OL JR :)

[MarkB.]

No, No,

In Canada its not a V-2, its an Eh-4.

[luke strawwalker]

No, No,

In Canada its not a V-2, its an Eh-4.

Hehehe... good one...

Know why there aren't many Canadian astronauts??

It's a PITA making space suits out of denim...

LOL:) Later! OL JR :)

[blackshire]

Hehehe... good one...

Know why there aren't many Canadian astronauts??

It's a PITA making space suits out of denim...

LOL:) Later! OL JR :)The late Neil Rogers, a South Florida talk radio host, once asked an interesting question regarding Canada: Is there a distinctively Canadian dish? He pointed out other nationally-related dishes (German sauerkraut, French quiche, British fish 'n chips, American hamburgers, etc.). Also:

He took some calls from Canadian listeners (tourists and "snowbirds" in South Florida). One woman suggested potatoes as being Canadian (two which Neil replied, "That sounds good, but I think the Irish might disagree with you..."). One man suggested Canadian bacon, but that isn't a complete dish. Poutine (thick-cut French fries served with gravy and chunks of cheese on them) was rejected because--although it is very tasty and enjoyable--it isn't necessarily a Canada-wide dish, being a Quebecois dish. After a while, several Canadians (including ones from Quebec) called in suggesting smoked meat because it is served everywhere in Canada, and Neil declared it the default "winner."

[blackshire]

Three other quasi-ballistic (semi-ballistic) missiles are the Lockheed Martin (formerly LTV [Ling-Temco-Vought]) MGM-140A ATACMS (Army TACtical Missile System, see: http://www.designation-systems.net/dusrm/m-140.html ), the MGM-168 ATACMS (see: http://www.designation-systems.net/dusrm/m-168.html ), and the MGM-164 ATACMS II (see: http://www.designation-systems.net/dusrm/m-164.html ). These comprise a family of externally similar surface-to-surface missiles that carry varying warheads. They all have ranges of over 100 miles (160 km), except for the MGM-164, whose maximum range is 87 miles (140 km). These single-stage, solid propellant missiles have combined GPS/INS (Global Positioning System/Inertial Navigation System) guidance systems that steer them by means of movable four-fin tail assemblies that are mounted on short, tapered boat-tails. Also:

Except for the MGM-164 (which has a bi-conical nose cone), all of the variants have ~3:1 length/diameter ratio nose cones that appear to be either secant ogives or Von Karman ogives (Haack-type nose cones). In addition:

I have noticed that the various U.S. and Russian quasi-ballistic missiles (SRAM, Iskander, ATACMS) have several common features. They have rather low total length-to-diameter ratios combined with longish bi-conical or secant ogive (or Von Karman ogive) nose cones; these features appear to enhance the missiles' maneuverability. Below are links to more information on the ATACMS series of missiles:


http://en.wikipedia.org/wiki/MGM-140_ATACMS (article has links to other MGM-140A articles)
http://www.astronautix.com/lvs/atacms.htm
http://space.skyrocket.de/doc_lau/atacms.htm
http://www.astronautix.com/lvs/atacmsii.htm
http://www.fas.org/man/dod-101/sys/land/atacms.htm
http://www.youtube.com/watch?v=Ipr_hPAcR_Q (ATACMS video)
http://www.youtube.com/watch?v=shl_4JgQAI4 (ATACMS video)

[luke strawwalker]

I always liked the look of the GAM-87 Skybolt... it was basically the predecessor idea to SRAM-- a semi-ballistic missile carried by bombers. The missile was designed to be carried by the B-52 or the British "V" series bombers (Vulcan particularly). The British canceled their long range ballistic missile (Blue Steel IIRC) in exchange for US promises to sell them Skybolts instead, but the Skybolt was canceled before it became operational, and the Brits got Polaris instead for their missile subs... They were canceled because it was determined that basically they had the drawbacks of both a missile (non-recallable once launched) and a bomber (vulnerable to enemy air defenses).

I particularly like the "transitioned" version, with the smaller nosecone and front (warhead?) compartment... it's just more visually interesting than the plain "long cone" version. The aft tailcone is just to streamline the missile when carried on the bomber's wing out in the wind, to cut fuel consumption on the bomber...

Here's some links, including pics of a predecessor vehicle to the Skybolt which I've never seen before... which would make an interesting rocket in it's own right!

http://en.wikipedia.org/wiki/Skybolt_missile
http://www.astronautix.com/lvs/skybolt.htm
http://www.brookings.edu/projects/archive/nucweapons/skybolt.aspx
http://en.wikipedia.org/wiki/Bold_Orion
http://www.afspacemuseum.org/missiles/Skybolt/index.htm
http://www.flickr.com/photos/davidjthomas/2221325209/
http://www.afspacemuseum.org/displays/Skybolt/index.htm
http://www.britmodeller.com/forums/index.php?showtopic=28493
http://www.strategic-air-command.com/missiles/Aircraft-Launched_Missiles/gam-87_skybolt_missile.htm
http://www.afspacemuseum.org/displays/Skybolt/index.htm
Later! OL JR :)

[blackshire]

I always liked the look of the GAM-87 Skybolt... it was basically the predecessor idea to SRAM-- a semi-ballistic missile carried by bombers.The Skybolt was a full-fledged exoatmospheric ballistic missile, with a range of about 1,000 miles. It flew "point-to-point" (with no "jinking" SRAM-type maneuvers), like a Thor or Polaris. After it was cancelled and the SRAM (whose range was just 1/10th of Skybolt's) was proposed as a replacement, defense "hawks" in the Congress referred to it as the "SHAM." That was a shame (pun intended!), because the SRAM had different mission objectives and was quite versatile (being able to fly an "orthodox" endoatmospheric ballistic trajectory, or fly as a low-altitude cruise missile with its terrain-following radar altimeter, or fly a "jinking" semi-ballistic trajectory that enabled it to strike targets ahead of, to the sides of, or *behind* its launching bomber--it kept the enemy guessing!). Also:

The SRAM was originally intended to take out enemy SAM sites along the routes to the bombers' primary targets for their nuclear gravity bombs. Later, the USAF targeting planners realized that the SRAM could serve as a stand-off weapon to strike primary targets in its own right, and B-52s were outfitted to carry large numbers of them in rotary bomb bay launch racks as well as on underwing pylons. The FB-111 and B-1B also carried SRAMs.The missile was designed to be carried by the B-52 or the British "V" series bombers (Vulcan particularly). The British canceled their long range ballistic missile (Blue Steel IIRC) in exchange for US promises to sell them Skybolts instead, but the Skybolt was canceled before it became operational, and the Brits got Polaris instead for their missile subs... They were canceled because it was determined that basically they had the drawbacks of both a missile (non-recallable once launched) and a bomber (vulnerable to enemy air defenses).Indeed. Also, the Skybolt's sequential test flight failures made it an easier target for the budget axe. Still, its cancellation caused quite a row between London and Washington at the time because the British had already spent a lot of money modifying their strategic bombers to carry Skybolts. Ironically, the Skybolt's first successful flight took place (if memory serves) on the day of the cancellation.I particularly like the "transitioned" version, with the smaller nosecone and front (warhead?) compartment... it's just more visually interesting than the plain "long cone" version. The aft tailcone is just to streamline the missile when carried on the bomber's wing out in the wind, to cut fuel consumption on the bomber...Same here! That was the "full-up" two-stage version. The version with the long conical nose cone was a first stage-only developmental variant that was used to prove out the air-launch technique, the operation of the frangible, "destroyed-at-first-stage-ignition" tail cone, and the first stage rocket motor and its control system.Here's some links, including pics of a predecessor vehicle to the Skybolt which I've never seen before... which would make an interesting rocket in it's own right!

http://en.wikipedia.org/wiki/Skybolt_missile
http://www.astronautix.com/lvs/skybolt.htm
http://www.brookings.edu/projects/archive/nucweapons/skybolt.aspx
http://en.wikipedia.org/wiki/Bold_Orion
http://www.afspacemuseum.org/missiles/Skybolt/index.htm
http://www.flickr.com/photos/davidjthomas/2221325209/
http://www.afspacemuseum.org/displays/Skybolt/index.htm
http://www.britmodeller.com/forums/index.php?showtopic=28493
http://www.strategic-air-command.com/missiles/Aircraft-Launched_Missiles/gam-87_skybolt_missile.htm
http://www.afspacemuseum.org/displays/Skybolt/index.htm
Later! OL JR :)Thank you very much! There are several that I had not come across before. Also, an air-launched ballistic missile (and ASAT proof-of-concept) test vehicle called High Virgo (see: http://en.wikipedia.org/wiki/High_Virgo and http://www.designation-systems.net/dusrm/app4/ws-199.html ) was tested in the late 1950s. A related ground-launched vehicle called Alpha Draco (which is also covered in those two above-linked web pages) tested an axisymmetric hypersonic boost-glide re-entry vehicle.

[blackshire]

Below is a good side view photograph of the AGM-131A SRAM II:

[luke strawwalker]

Below is a good side view photograph of the AGM-131A SRAM II:

Looks like an artillery shell with fins... LOL:) Not as aesthetically pleasing as the SRAM's lines are...

Point taken on the differences between SRAM and Skybolt... it's interesting how ideas go around again and again, just taking various routes, forms, and functions...

The craziest idea I've read about was the idea of "air-mobile" basing of Minutemans... or a miniature version of them called Midgetman... been awhile since I read it but I remember they wanted to carry them in a regular cargo plane (of sufficient size) and simply roll them out the back for launch... they'd fall under a parachute until they stabilized their swinging from being dumped out of the plane, then ignite the rocket motors and fire a charge to sever the parachute, flying through it on the way up into the regular ballistic trajectory...

Another case of "worst features of both a missile AND a bomber..."-- non-recallable, and vulnerable to surprise attack or destruction on the ground if the launch planes didn't get up in time...

Later! OL JR :)

[blackshire]

Looks like an artillery shell with fins... LOL:) Not as aesthetically pleasing as the SRAM's lines are...I agree--I just posted it for completeness' sake. It would make an easier-to-build beginner's scale model, though.Point taken on the differences between SRAM and Skybolt... it's interesting how ideas go around again and again, just taking various routes, forms, and functions...Yes. I had never paid much attention to the SRAM, and I didn't appreciate its unusual capabilities until I read up on it (and on semi-ballistic missiles in general) recently. The USAF still misses not having its capabilities. The U.S. Army's ATACMS has much the same maneuvering capabilities and the same range (>100 miles when ground-launched, which should be better if it was air-launched). Since the ATACMS is about the same size as the SRAM, maybe it could be adapted for being carried aboard B-52s and B-1Bs?The craziest idea I've read about was the idea of "air-mobile" basing of Minutemans... or a miniature version of them called Midgetman... been awhile since I read it but I remember they wanted to carry them in a regular cargo plane (of sufficient size) and simply roll them out the back for launch... they'd fall under a parachute until they stabilized their swinging from being dumped out of the plane, then ignite the rocket motors and fire a charge to sever the parachute, flying through it on the way up into the regular ballistic trajectory...The USAF conducted one test in 1974, using a Minuteman I that was launched in that way from a Lockheed C-5A Galaxy. The Minuteman I's "short-loaded" first stage motor ignited successfully and burned for 10 seconds. The test was successful, but the idea was not proceeded with; I'll bet that the inflation of that time combined with the then-emerging detenté with the Soviet Union were the reasons. (If memory serves, 1974 was also the year when a Minuteman III was successfully test-flown with seven MIRVs--detenté is probably what put the kibosh on that improvement.)Another case of "worst features of both a missile AND a bomber..."-- non-recallable, and vulnerable to surprise attack or destruction on the ground if the launch planes didn't get up in time...

Later! OL JR :)Indeed--and after the airborne alert B-52 carrying four hydrogen bombs crashed just offshore at Thule AFB, Greenland in 1968 (a friend of mine witnessed the crash--the bomber *just* missed the submarine cable building where he was working; he saw one of its wingtip outrigger landing gear flash by a window!), I'm surprised that the Air Force even considered airborne carriage of full-size ICBMs. A B-52 carrying SRAMs would have made a radioactive mess if it crashed, to be sure, but a much larger Minuteman would probably have scattered radioactive debris even more widely in the event of a crash and explosion.

[UhClem]

Except for the MGM-164 (which has a bi-conical nose cone), all of the ATACMS variants have ~3:1 length/diameter ratio nose cones that appear to be either secant ogives or Von Karman ogives (Haack-type nose cones).

ATACMS Block I and IA:

3.07:1 Von Karman.

Block II: 1.87:1 Von Karman. (I think it was 1.87 but it has been a while.)

One thing that can cause some confusion is that the boundary of the VK profile is not at the paint line even though it is close. On the Block I the paint line (joint between motor and payload section) is behind the start of the VK profile. On the Block II the paint line (joint between payload section and nose) is ahead of the start of the VK profile.


The Block II looks odd in most pictures because that is the flight test configuration that has a big wrap around antenna mounted on the nose for telemetry, radar transponder, and flight termination system antennas. The antenna is conical but it is mounted on a VK profile nose cone.

http://www.designation-systems.net/dusrm/mgm-140c.jpg

In this image the center payload section is a dark color, a dull rust red primer, while the nose is an ugly green color. A bit back from the nose tip is a dark band which is the telemetry antenna. If you want the color for that it is the natural color of Rogers RT/Duroid.

[blackshire]

Thank you very much for posting this additional ATACMS scale data, UhClem! I thought the ATACMS nose cone (particularly the Block I's) was a Von Karman ogive. I wasn't able to directly open your linked photograph of the Block II ATACMS (the Designation Systems web site blocks hot-linking of its photographs, although its article pages [which contain images] can be hot-linked, as I've done it on YORF for a long time), but after e-mailing the link to myself I was able to open it. Also:

I see what you mean--the wrap-around conical (frustum?) antenna section on the rear portion of the ATACMS Block II's nose cone does give its shorter Von Karman ogive nose cone a bi-conical appearance. While Von Karman ogives aren't common model rocket nose cone shapes, I believe Semroc's www.semroc.com custom nose cone designer utility can handle them (and I'm pretty sure they can turn them to a customer's specifications without that utility, if the ordinates are supplied). In addition:

Are you involved in working on the ATACMS weapon system? The reason why I ask is because I recently brought up the subject of the USAF possibly adopting the ATACMS to re-gain its bombers' lost SRAM semi-ballistic missile capability (for precision convential warhead delivery as well as for nuclear bombardment) to a retired Air Force Colonel I know, and he liked the idea and passed it along to a few high-ranking active-duty USAF officers he knows. If the Air Force began using the ATACMS as an air-launched weapon (called the SRAM III, perhaps?), the larger procurement quantities of the missile (between the Army and the Air Force) should lower its unit price.

[UhClem]

I was a telemetry weenie on that program for a while.

As for the USAF, have you read about the history of ATACMS? About how it was once JTACMS (J for Joint) until the USAF dropped out?

The Redstone history site is down at the moment but The Wayback Machine has it:

http://web.archive.org/web/20100212004412/http://www.redstone.army.mil/history/systems/ARMYTACMS.html

I don't see them changing their minds at this late date.

[NAR29996]

SRAM's radar guidance is more properly called terrain avoidance. Terrain guidance is more appropriately used on the AGM86B ALCM. I was a missile tech on both, a long time ago.

[blackshire]

SRAM's radar guidance is more properly called terrain avoidance. Terrain guidance is more appropriately used on the AGM86B ALCM. I was a missile tech on both, a long time ago.Thank you. That explains (at least in part) the SRAM's pretty large CEP (Circular Error Probable). It was launched toward a target point that was programmed into its inertial guidance system, and if the low-altitude flight path option (as opposed to the high-altitude, semi-ballistic flight path option) was selected, the terrain avoidance radar's inputs made the missile steer clear of any obstacles on the way to the target point.

[NAR29996]

That's what we were hoping for.

[blackshire]

That's what we were hoping for.The tone of your comment mirrors what I've read about the SRAM--"reading between the lines," the documentation gives the impression that "on paper, the SRAM has X, Y, and Z low-altitude capabilities, but we're not fully confident that it could do them under operational conditions..."

[NAR29996]

It's too bad (although understandable) that the Bullet Blitz results are unavailable. I had heard a rumor that one came within 100 feet of target, but that was the exception.

Bullet Blitz were test flights of missiles on alert status.

BTW, no one seems to talk about the SRAM variant that was the first stage of a proposed US ASAT system. One test was done in the mid '80's, launching from a F15.