ELAH · DAVID 120mm interceptor

Today’s situation

Threat inbound.

ENEMY UAS INBOUND · GRID 11S MC 8421 3396

This is a normal morning on 2030’s battlefield.

Today’s drill

Grab as much as you can and take cover.

Hope that there is an active C-UAS system to deal with the threat.

What happens:

Damage to equipment
Potential casualties

DAVID in flight configuration: wrap fins deployed amidships, canards forward, the launch boom shed.

It leaves as
ammunition.
It arrives as
an interceptor.

01 Increments burn off
02 Boom and tail array separate
03 Nozzle uncovered
04 Fins and canards snap out
05 Target locked

GUIDANCE

Nothing to jam.

A passive infrared seeker finds the target. A 77 GHz radar wakes for the last second and fires the fuze. The round carries no receiver, no datalink and no GPS.

Seeker: Uncooled LWIR microbolometer
Fuzing: 77 GHz mmWave impact & proximity fuze
Warhead: 0.5 to 1.5 kg preformed fragmentation
Propulsion: Expendable micro turbojet
Targeting: Infrared & radar probe antenna
Control: Maneuverable aero

DAVID drawn as a specification plate: the round laid out horizontally with its parts separated along one axis. Left to right, the probe antenna and radome ahead of the hull, the hull with its canards and fins lifted clear of it, then the engine, the exhaust fairing and the launch boom drawn off the tail.

DAVID in flight, seen from behind and above: the turbine and its exhaust ring fill the near frame, fins and canards deployed, and a Shahed type attack drone is ahead of it in the distance, banking across the round’s line of flight.

Tomorrow’s drill

Stay on the gun.

The same tube. The same crew. The same drill they already know.

Same round. New effects.

Created for the gun section that is already employed in the battlefield.

Unit cost, and what it buys

The Army paid $24,469 for the same round that simply “improved accuracy.”

Comparable effectors. Cited figures are public procurement records; the DAVID row is a concept target.
Effector	Unit cost	Launch system	What it can reach
M934 120mm HE	$2,000	M120	Ground
XM395 APMI, GPS guided 120mm	$24,469	M120	Ground, accurately
DAVID, this concept	$25,000	M120	Air
Coyote Block 2	$125,000	LIDS launcher and KuRFS radar	Air
Patriot interceptor	$4,000,000	M901 launching station	Air

Same tube. Same crew. Same money. This one goes up.

AMMUNITION DATA CARD

Notional Specifications

Nothing here has been built and nothing has flown. Every figure is a design target, derived from the M934 envelope, the M120 firing table and parts that can be bought today. The sources are at the foot of the page.

Identification

Nomenclature: CARTRIDGE, 120MM: INTERCEPTOR, GUIDED, DAVID
NSN: 1315‑01‑___‑____
DODIC: PENDING · assigned by the US Government. M933 is C623, M934 is C379.
Colour code: Olive drab body, yellow band, white stencil, per MIL‑STD‑709D
Hazard classification: UN 0321, 1.2E provisional. Onboard fuel drives its own IM series.
Packing: Four rounds, sealed container, 68 kg gross

Physical

Calibre: 120 mm, smoothbore, muzzle loaded
Overall length: 711 mm. The M934 envelope, unchanged.
All up weight: 14.6 kg
Weight after separation: 12.3 kg
Span: 120 mm stowed, 410 mm across the deployed fins

Launch

Weapon: M120 and M121, no modification. M326 stowage compatible.
Charge: Increment 2. Increments 3 and 4 are not authorised.
Muzzle velocity: 165 m/s at +21 °C
Elevation: 1,100 to 1,500 mils (62 to 85 degrees)
Setback: 10,000 g peak, about 12 ms
Boom separation: T + 2.4 s, about 360 m above the tube
Turbine light off: T + 2.9 s. Gas generator spins the spool; no starter motor.

Propulsion and control

Propulsion: Single spool turbojet, 100 N class, 97 mm diameter
Fuel: 0.95 L JP‑8 with 5 % turbine oil
Endurance: About 150 s at maximum thrust
Speed: 230 m/s level at 3,000 m, thrust limited
Control: Four canards, ±18°, electromechanical actuators
Manoeuvre: 10 g commanded, 14 g structural
Guidance: Proportional navigation, N = 4
Navigation: MEMS inertial, 10 °/hr bias. No GNSS.
Power: Thermal battery, 28 V, 180 s

Seeker and effect

Seeker: Uncooled LWIR microbolometer, 640 × 512 at 12 µm, 60 Hz, 24° field
Acquisition: About 2,500 m against a Group 3 airframe
Terminal radar: 77 to 81 GHz FMCW, 4 GHz sweep, 3.8 cm range resolution
Fuzing: Impact and radar proximity. Two environment safe and arm, MIL‑STD‑1316.
Warhead: 1.2 kg preformed fragmentation, PBXN‑109, about 600 tungsten cubes at 4 mm
Emission: The seeker is passive. The radar is the only emitter and it wakes for the last two seconds.

Engagement and service

Envelope: 1,000 to 5,000 m slant
Time to intercept: 6 to 30 s from the tube
Target set: UAS Groups 1 to 3. Not 4. Not 5.
Storage life: 20 years, no periodic maintenance
Temperature: −46 to +71 °C stored, −32 to +49 °C fired
Unit cost at rate: $25,000 target, at 10,000 rounds a year

Two rows here carry the risk, and neither one of them is the cost. The seeker finds a Group 3 airframe at about 2,500 m and the envelope is written to 5,000: the difference is the platoon’s own counter battery radar putting the round in the basket, and without that handoff this is a short range weapon that has to be pointed. The other is the charge restriction. Increments 3 and 4 are withheld not for range but because a turbine spool, a thermal battery and a microbolometer all have to come through 10,000 g still working, and that is a rig test, not a drawing. Everything else on this card is arithmetic off an envelope the M934 already occupies.

Start the conversation

An M120 120mm mortar emplaced and ready to fire: the black steel M298 tube standing at about seventy degrees with its white alignment stripe, the olive drab M190 bipod spread beneath it with the sight on the left and a chain slung between the legs, all seated on the rounded triangular M9 baseplate. — The M120 is a system used for generations and generations to come.

Fielded in 1991 and still the battalion’s heaviest organic fire. Every round on the card above is fired from this, unmodified.

M120. Air defense.