Radiant heat weapons

Discussion in 'Weapons, Equipment & Rations' started by IndependentBoffin, May 26, 2011.

Welcome to the Army Rumour Service, ARRSE

The UK's largest and busiest UNofficial military website.

The heart of the site is the forum area, including:

  1. Recently, I burnt my hair whilst experimenting with a small quantity of (non-explosive) energetic material. My hair was approximately 1m from the heat source, while my arms and fingers (in electrican's gloves, trashed) was intermediate in distance. Despite the proximity of my arms to the heat source, the exposed skin on my arm was fine while my hair got burnt. Why?

    The reason is because when exposed to a radiant heat source, objects with a high illuminated surface area to volume ratio experience the greatest heating. This is because the illuminated surface area governs the heat absorption, while the volume is related to the thermal mass of the object.

    This interesting observation makes plain the vulnerability of a plethora of objects with a high surface area:mass ratio, particularly active/passive sensors, comms, aerodynamic surfaces, etc. Consider a plain cylindrical antenna. While it is possible to reduce the vulnerability of such an antenna to fragments and blast waves by reducing its length or diameter, its vulnerability to heat flux actually increases with decreasing size (1/R relationship).

    A common theme among modern and anticipated military hardware are improvements in C4ISTAR and network centric capabilities. Being able to field weapons that would consistently blind/mute these capabilities in a broad variety of existing and future targets (including EMP hardened) would be a disruptive evolution in weapons technology.

    Furthermore, it is not economical or even practical to harden some military hardware against heat shock weapons, e.g. aerodynamic surfaces. Not only are high surface area:mass ratio components vulnerable, so are geometries which form said components - e.g. a sharp edge will heat up faster than the bulk of a component. So wing/rotor trailing edges and ERA tiles (because the explosives we are trying to cook off are staggered at an angle within the plane of the tile) are additionally vulnerable.

    Examples of possible targets:

    Armoured vehicles: Tanks, APCs, IFVs, etc.
    Vulnerabilities: communications equipment, sensors, explosive reactive armour tiles, main and secondary gun barrels
    Outcomes: loss of communication capabilities, blinded sensors (e.g. active defence radars), ignition and cook-off of ERA tiles, ignition of exposed fuel tanks or ammunition, distortion of gun barrels to outright destruction of weapon systems

    Vulnerabilities: trailing command wires (if applicable), control surfaces, casing, sensors (if applicable)
    Outcomes: loss of control or aerodynamics, cook-off of propellant or energetics, blinded sensors

    Naval vessels: skiffs, destroyers, carriers or submarines
    Vulnerabilities: Comm and sensor arrays, gun and non VLS-missile tubes. Asymmetric loss of displacement by detonation of a thermal shock weapon under the hull resulting in flash boiling of water.
    Outcomes: loss of hull integrity, leaks, degradation of capabilites,mission-kill. If the radiant warhead pierces the hull and goes off within the vessel - onboard fires, cook off and extensive destruction of equipment and structure is likely.

    Aircraft: helicopters, planes
    Vulnerabilities: aerodynamic surfaces, armaments, external fuel tanks
    Outcomes: delamination of composite surfaces, fuel leaks/fires, cook-off, blinding of pilots

    Vulnerabilities: corneas, exposed skin
    Outcomes: blindness, incapacitation, death.

    How does one achieve such temperatures in a practical non-nuclear weapon system? Marketing blurb: I happen to have some solutions to that, if I find a suitable sponsor for proof-of-concept work to investigate this entirely new, exciting class of weapons (Arrse has been very helpful in putting me in touch with the right people). Suffice to say if we can agree on the principle and the physics, we can then work on the engineering of it.

    For now though let's look at the potential of high temperature, thermal shock weapons. I have already described how such a weapon has broad spectrum capability against a variety of targets. What is also very interesting is that if battlefield sources of intense heat could be deployed, the effectiveness of such weapons are clearly defined by physical laws. For example, decay of the radiant heat from a point source is inversely proportional to the radius squared. If aimed at a main gun barrel or threads, crippling of the tank and a mission kill is likely. If aimed at a distance further away from the tank, cookoff of ERA tiles, blinding of sensors and burning off of antennae are likely. Therefore, weapons based on radiant heat would be both multi-target and multi-role, capable of engaging a wide variety of targets across the entire force escalation spectrum.
  2. How would it differ from (say) the thermobaric and flame available for the RPO ? The trick will be convincing customers that it is better than what is in service at the moment.

    Drawbacks I see are that it will set anything near on fire far more readily than current weapons. The implications for land use - partucularly urban - are obvious. And if performance in rain is reduced enough then again, why bother. And countermeasures at sea could be as simple as spraying water in a cloud surrounding the vessel. Ships already have NBC washdown systems, after all.
  3. What about the geneva convention would it not be quite against a wepaon that deliberatly causes blindness? I'm assuming this blindness is not temporary but would cause a rather debilitating effect vs infantry, mind you if it is accepted it would probably crush enemy morale like a boulder, or am i barking up the wrong tree?
  4. Ever since the photograph of those burned children running from the Vietnamese village with their skin hanging off in blackened lumps, heat and flame weapons have been politically problematic, to the extent that the US tried at first to deny using them in Desert Storm. I mention the photograph advisedly, as it would be plastered all over the Press the moment a Government in any democracy considered its purchase or deployment.

    A non-starter, politically. If you want to sell to dictators, Iran and the like, then crack on. It's your conscience.
  5. Napalm or thermobaric weapons don't get hot enough. If you look at the pictures below (napalm and a thermobaric bomb) and consider the flame colour as a rough measure of its temperature, the temperatures are around 2000K.

    In fact the temperature of burning napalm is around 1500K and it probably looks hotter in the pictures presented than IRL because the photographs are not a true representation of the colours.

    Napalm - Wikipedia, the free encyclopedia

    Even thermites don't get hot enough - around 3000K.

    Based on the Stefan Boltzmann law (fourth power dependence on absolute temperature), the radiant heat output per unit area of a black body at 1500K (napalm) is 0.287MW/m^2. At 3000K (thermites) it is 4.59 MW/m^2.

    Now if we could field a practical weapon that produces temperatures in the range of 6000K - 10000K, we are talking about areal power outputs of 73.5MW/m^2 - 567MW/m^2.

    If you consider that lightning has temperatures up to 28000K, we know that it is possible to achieve irradiances of 34900 MW/m^2 in a non-nuclear system.

    If a good radiant heat weapon is fielded it should be characterised by brilliant, intense blue-white flashes of light, capable of blinding the naked eye some distance from the targeted point and flash melting/boiling/igniting nearby equipment.

    Attached Files:

  6. I would have to scrutinise the terms of the Geneva convention but the main purpose of the weapon is to destroy sensors/comms/etc. by radiant heat - anything with a high surface area/thermal mass ratio.

    The human eye actually has an optimal geometry for protection against radiant heat (a sphere has the lowest possible surface area:volume ratio of any geometry) unfortunately it is such a delicate organ that it doesn't take much to cause injury to it.

    I suspect blindness caused by a radiant heat weapon to the eyes would be classified as a secondary or tertiary effect, like WP rounds being classified as illuminant or smoke generating rounds (hence lawful).
  7. No I don't do business with anyone associated with Islamic terrorism or militancy (personal religious reasons) or dictatorships (personal political motivations).

    Problem with napalm is that it splashes, flows around and is indiscriminate. KE rounds may ricohet or overpenetrate. Fragments from fragmentation weapons can travel far from the detonation point. Thermobarics are mayhem in populated areas. All of these weapons add a random element to the possibility of causing unintended casualties.

    However, radiant heat weapons are highly uniform, consistent and predictable in their desired effect from the target point. You can mathematically define the radius where just temporary blindness happens, to destruction of comms gear and finally to flash melting/boiling/ignition of key exposed vehicle parts.

    If such a weapon injures/kills non-combatants, it can only be because of a mistake in selection of the target point or bad intelligence as to what was actually around the target point.
  8. I'm not talking about the minutiae of weapon design, I'm talking about the shitstorm the Press would stir up if word got out that MOD was looking at weapons that killed with fire. The reality of what you intend would be naught beside it.

    And do you really want a picket line of Guardian readers outside your house?
  9. You are Leonard of Quirm and I claim my £5

  10. I think the one big problem with this is the classic "complex weapon, simple countermeasure" one.

    If the antenna was polished up to a mirror shine, how much less effective would the weapon become?
  11. Well, technically, the main way this would kill someone is by light, not fire, but I see your point. It will be distorted by the media to suit their readership. And no I don't want any pickets outside my house. I have enough lively debates with my socialist housemates as it is.

    In theory if the person is close enough to the aim point of the weapon they can be knocked out by the same mechanism that stuns people affected by the Pulsed Energy Projectile.

    Pulsed Energy Projectile - Wikipedia, the free encyclopedia

  12. I once sat a bit too close to my Gran's gas fire and got uncomfortably warm.
  13. Reflectance of an object is wavelength dependent. Something that may be reflective to optical wavelengths might absorb radiation at other wavelengths - infrared, near UV, etc.

    An ideal radiant heat weapon would generate an intense local hotspot with high emissions in the UV range. Over time as the hotspot cools this will shift to visible then IR wavelengths.

    Also the reflective layer added mustn't impair the function or feasibility of the device you are trying to protect.