9 - 1 1 R e s e a r c h aluminothermics at the WTC * essays

A Hypothetical Blasting Scenario

A Plausible Theory Explaining the Controlled Demolition of the Twin Towers Using Aluminothermic Incendiaries and Explosives with Wireless Ignition Means

Jim Hoffman
Version 1.0, April 4, 2009
Version 1.2, April 9, 2009


Most science-based investigators of the events of 9/11/2001 are reluctant to develop detailed hypotheses or conjectures for obvious reasons: to speculate about unknown events in a criminal conspiracy is to invite the label of "conspiracy theorist" with its weight of discrediting associations, unless, of course, one is parroting the speculations of the officially endorsed account.

Never mind that NIST explains WTC7's destruction as the first-ever fire-induced collapse of a steel-frame high-rise building with the refreshingly novel failure mechanism -- supported by no physical evidence whatsoever -- that thermally induced expansion of a huge beam caused it to break loose of its connections and crash down, taking the rest of the skyscraper with it. It is the skeptics of this fairy tale that New York Times reporter Eric Lipton calls conspiracy theorists. [1

The chief apologists for the official story seem to want it both ways. On the one hand, they stigmatize anyone who questions the official version of events as a "conspiracy theorist". On the other, they fault the same intellectual dissidents for not articulating a detailed theory of the crime, as Ryan Mackey does here. How interesting that the conspiracy theorist label remains the first line of defense against the consideration of alternative hypotheses, while the main arguments against controlled demolition of the Twin Towers appeal to alleged difficulties in implementation -- arguments that can only be answered through postulating hypothetical scenarios.

Here, then, is such a scenario -- in much more detail than suggestions I have previously made to answer frequently asked questions -- that I hope will be useful to other investigators working to solve the horrific crime of '9/11'.



The present scenario is a detailed hypothetical account of the method by which each of the Twin Towers was totally destroyed. Although the visible pattern of destruction of the North and South Towers differ in details, they both fit the same general description: The block above the crash zone starts to move, accompanied almost immediately by dust ejections, then disappears into the exploding dust cloud, which progresses down the vertical axis of the Tower's intact portion leaving nothing standing but portions of the core, which then falls apart. The similarities in the patterns of destruction, as well as the nearly identical structures of the Towers themselves, suggests that essentially the same method was used to destroy each Tower, with adjustments of that method to account for the differences in the plane crashes. The scenario is described for the general case of either Tower. It postulates that the plane crashes were planned and executed with some degree of precision, using their automated flight control systems, and the adjustments in the demolition method planned accordingly.

As noted in the summary of the aluminothermics evidence timeline, there is direct evidence for two broad types of thermitic pyrotechnics in the destruction of the Twin Towers:

  • Incendiaries, consisting of thermate or thermate possibly with additives such as barium nitrate
  • Explosives, consisting of aluminothermic nanocomposites including compounds rich in silicon, carbon, and hydrogen to enhance blast pressure

The scenario reflects this dichotomy in postulating that two distinct stages comprised the demolition of each Tower: a first stage in which strategically-placed thermitic incendiaries attack steelwork while the Tower is still standing, and a second stage in which widely distributed thermitic explosives shatter the Tower from top to bottom.


Method Overview

The destruction of each of the Twin Towers is accomplished by an almost identical overall sequence, consisting of two stages -- a slow first stage, in which key portions of the steelwork are melted and corroded, and a rapid second stage, in which key structures are broken, and the entire Tower is systematically pulverized from the crash zones down. The time T-0 marks the onset of Stage 2.

1: Steelwork Thermal/Corrosive Attack 2: Steelwork Knocking and Progressive Distributed Blasting
material aluminothermic incendiaries enhanced with sulfur aluminothermic nanocomposite explosives including silicon, carbon, hydrogen
application as coatings applied directly to steelwork in the core structures around the crash zone and the hat truss as fire-protected kicker charges in close proximity to core steelwork around the crash zone as thin-film explosives distributed throughout alternate floors within ceiling tiles
timing commencing at up to T-10 minutes with burnout shortly before T-0 T-0 through T+2 seconds around crash zone commencing at T+0.5 seconds below crash zone, and accelerating down the Tower to T+12 seconds

Pyrotechnics Features

The pyrotechnics are of three types, all based on aluminothermic reactions: an incendiary used in the Stage 1, and two types of explosives used in Stage 2:

  • Thermate incendiary coating compound: A mixture of aluminum powder, iron oxide powder, sulfur and other additives in a binder. Applied in a liquid form like paint, it dries to form durable coating that requires a high-temperature igniter to start the reaction by heating a spot to the 2,200ºC ignition temperature.
  • Nanothermite kicker charge: A large forceful charge with relatively low brisance based on a nano-thermite explosive that is stable up to a very high temperature and pressure, such as supplied by a built-in detonator. A protective insulating capsule is shaped like a fire-extinguisher bottle.
  • Aluminothermic nanocomposite sheet: A thin layer of a nanocomposite aluminothermic material laminated onto a thin brittle slab of iron oxides and hydroxides. The material deflagrates (burns gradually) when elevated to 430ºC, but detonates with high brisance only when extremely high temperature and pressure, such as provided by a micro-detonator, is applied to any part of its surface.

Because these pyrotechnics are energy-dense, have very specific conditions of ignition and detonation, and leave residues composed of the same elements as building parts; they are well suited to the covert demolition of the Twin Towers. Surprising to most people given popular conceptions about explosives, the energetic materials' characteristics allow them to be deployed throughout the crash zones without risk of premature detonations.

The incendiary coatings are unlikely to be ignited by the jetliner crashes because their ignition threshold temperature is so high. But in the event that some are, they will blend in with the hydrocarbon fires.

The kicker charges have very specific detonation conditions unlikely to be achieved even by direct impacts of jetliner parts, let alone office fires, and are further protected by encapsulation.

Without the very rapid pulse of extreme temperature and pressure required to trigger detonation, the nanocomposite sheets will deflagrate on ignition, and do so slowly enough to appear to burn like office furnishings.

Control Architecture

Ignition of the incendiaries and detonation of the explosives is controlled through a wireless network using RF repeaters on every floor of the Towers having pyrotechnics.

Each of the Stage-2 pyrotechnics units -- the kicker charges and explosive sheets -- has an integrated wireless detonator card that includes a 2-channel RF receiver, an accelerometer, logic, dual wafer batteries, and a micro-detonator. The card is cemented onto the surface of the pyrotechnic's thermitic material so that the detonator is in contact with the material.

Similar electronics packages with high-temperature igniters are designed to adhere to the surface of the incendiary coating.

The detonator cards are programmed to respond only to RF signals on the network's broadcast frequencies that have specific codes. The cards are manufactured in batches of cards with identical codes, where each batch has a unique code and is destined for a specific floor of one of the Towers.

Of a detonator card's two channels, one provides the arm signal, and the other provides a detonation signal. Once the arm signal has been received, the detonator will be triggered by either of two events: rapid acceleration detected by the accelerometer, or receipt of the detonation signal.

The detonators are under the wireless control of the RF repeators located on most floors. The repeaters are redundantly controlled from an operations center located a safe distance from the Twin Towers via both high-power directional wireless and an encrypted ethernet channel. The repeaters all broadcast the same signals with ample power to be easily detected by all the detonator receivers on the same floor as well as by most on nearby floors.

Equipment Procurement

The following table lists the materials required for both Towers.

part quantity
20"x20"x3/4" ceiling tile with embedded thin-film explosive and 2-channel wireless micro-detonator 1,000,000
12"x12"x3/4" ceiling tile with embedded thin-film explosive and 2-channel wireless micro-detonator 800,000
10-lb nano-thermite kicker charge with 2-channel wireless detonator in fire-protective capsule disguised as fire extinguisher 100
5 gallon thermate coating compound 20
spray applicator with flexible snake hose and integrated borescope 2
2-channel wireless high-temperature igniter 100
20-channel 200W RF repeater with UPS 240

All of the equipment is available off-the-shelf from commercial vendors or special operations supply depots except for the wireless explosive ceiling tiles, which have to be specially manufactured. The tiles are assembled at a facility that is supplied with pre-manufactured materials and parts, some only for secret military applications: 2-channel wireless micro-detonators in the form of thin-profile cards, nanocomposite thin-film explosives in the form of pre-cut sheets, and acoustic-tile fiberboard sheets pre-cut to the correct sizes and pre-painted. The facility cements a detonator to the sheet, and laminates the sheet between two pieces of fiberboard.

Equipment Installation

The scenario allows all of the equipment installation to be disguised so that the very workers doing the installation work are oblivious to the fact that they are installing demolition equipment. None of the equipment looks anything like conventional demolition gear, and there is a fully plausible innocent explanation for each procedure. There are no wires connecting components. Even on close examination the equipment would not reveal its true purpose. If a worker were to break open a ceiling tile and find the nano-thermite film layer, his supervisor would explain what he was told -- that the new energy-efficient tiles have an embedded a vapor- and radiative-heat-loss barrier.

The labor-intensive portions of the operation might be made more secure by using undocumented workers who are naturally disinclined to raise questions about the work.

Steel Work

The only part of the installation work that requires direct access to steelwork is the application of the thermate coating compound and the attachment of high-temperature igniters to the coated areas. Because this treatment is applied only to steelwork in the core around the planned crash zone and the hat truss, the number of access points is relatively small, and can be reached almost entirely through parts of the building controlled by building services.

The use of a spray applicator with a flexible snake hose and integrated borescope allows a worker to treat an entire section of column walled off by sheetrock by drilling a few 2-inch-diameter holes in the sheetrock, perhaps above the level of the ceiling tiles. Such efforts to make the work inconspicuous are hardly critical, given that the work is supposedly to upgrade fire protection of the steelwork. And, if anyone asks, the igniters are vibration detectors used to monitor the structure's performance in high winds.

Ceiling Tiles

The replacement of ceiling tiles throughout the building may have been done on any of a number of schedules. On the one hand the tiles could have been supplied as part of an maintenance contract and installed using the existing building maintenance staff doing what they thought of as normal building maintenance work. Since the new landlord had just taken over in late July of 2001, it wouldn't seem at all unusual to see some refurbishing, especially as unobtrusive as swapping out old ceiling tiles.

Alternatively, the tiles could have been installed during overnight hours by a team of maintenance workers unnoticed by tenants. The logistics of such an operation can be imagined, and some estimates of human resources made.

We know that the Towers had only two types of ceiling tiles: 20-inch squares for the tenant spaces and 12-inch squares for the core spaces. An estimate of the number of tiles per tower is 1,200,000 large tiles and 800,000 small tiles.

5.8.4 Ceilings

There were two different ceiling tile systems originally installed in the towers under Port Authority specification. The framing for each was hung from the bottom of the floor trusses, resulting in an apparent room height of 8.6 ft and an above-ceiling height of about 3.4 ft. The tiles in the tenant spaces were 20 in. square, 3/4 in. thick, lay-in pieces on an exposed tee bar grid system. The tiles in the core area were 12 in. square, 3/4 in. thick, mounted in a concealed suspension system.

-- NIST Final Report on the Twin Towers

The new ceiling tiles with embedded thin-film explosives and wireless detonators are installed throughout every other floor of the Tower. In all, each Tower gets 500,000 of the large tiles and 400,000 of the small tiles.

With workers swapping in new tiles at an average rate of two tiles per minute per worker, it takes a team of forty workers 187 hours to retrofit an entire Tower. The work is performed in three weeks and weekends of night shifts, emptying one truckload per night, with the truck parking inconspicuously in the WTC subterranean parking garage.

Kicker Charges and Wireless Equipment

The remaining equipment is installed with a minimum of effort. The 20-channel repeaters are installed in communication equipment closets on each floor having the ceiling tile retrofits, and on floors having treated steelwork and kicker charges. The repeaters are cabled to existing ethernet ports, through which they can receive encrypted instructions.

The kicker charges are mounted in closets and elevator shafts, generally just above portions of the structure that have been treated with the thermate coating compound.

Summary of Concealment Methods

In all cases, the concealment of the demolition equipment has at least two layers. On the surface, each item appears to have an innocent function. The installation of the equipment is designed to go unnoticed, but even if noticed there is nothing about the procedures or equipment that would tend to arouse suspicion. In the event that equipment is scrutinized, as by the unlikely event of someone breaking open a ceiling tile, there is a plausible explanation for the features of the equipment, summarized by the following table.

equipment explanation/disguise
thin-film explosives embedded in ceiling tiles vapor barrier and energy-conserving infrared reflector
low-profile igniters embedded in ceiling tiles smoke detectors
kicker charges fire extinguishers
thermate coating on steelwork fire protection upgrades
non-embedded wireless igniters vibration sensors for structure monitoring
RF repeaters communications equipment

It also bears noting that all of the pyrotechnic materials are based on the thermite reaction and do not involve the kind of nitro-aromatic compounds whose residues are the most likely to be tested for in a crime scene investigation.

Demolition Sequence

The demolition sequence is designed to conceal the fact of its being a controlled demolition despite using perhaps two orders of magnitude more explosive energy to destroy the Tower than would be required in a conventionally engineered controlled-demolition implosion. A key objective is get the top of the Tower to move before explosive action is clearly evident to onlookers outside the building.

The two stages outlined above, separated by the time T-0, are designed to achieve this objective by sufficiently degrading key parts of the structure in Stage 1 so that the relatively small kicker charges can produce movement in the top at the onset of Stage 2.

Stage 1: Thermate Melts and Corrodes Core Steelwork

During Stage 1, extending from up to 10 minutes before T-0, thermate coatings on key parts of the core structure steelwork are ignited via the wireless ignition control system. The two areas attacked are: the core columns on a few floors below the crash zone, just above where most of the columns transition from box columns to wide-flange beams; and the inner portions of the hat truss that connect it to the core.

The thermal/corrosive attack on these two portions of the structure leaves the entire block of the core structure above the upper mechanical equipment floor "floating", with no major steel members to transfer its gravity loads to the lower portion of the core or to the perimeter walls: it is now supported by the web-trussed floor diaphragms. The upper core block now exerts massive inward forces on the perimeter walls due to the high degree of leverage involved in the translation of the core block's gravity loads into pulling on the perimeter walls. It is these forces that produce the inward bowing of portions of perimeter walls that NIST claims are due merely to the sagging of floor diaphragms still supported by the core.

Partly because thermate produces bright orange light while burning, Stage 1 is allowed time to run to completion before Stage 2 commences. In the South Tower, some thermate pushed by the plane crash from the building's core to its corner generates an orange spout lasting from about T-7 to T-2 minutes.

Stage 2A: Kicker Charges Initiate Motion of Top

At the onset of Stage 2, kicker charges mounted just above the core steelwork attacked in Stage 1 are ignited by the wireless control system, fully detaching the core's upper block from its base and from the hat truss, and causing it to fall several feet. Half a second later, ignition of thin-film charges around the crash zones start. The jolt provided by the short fall of the core's upper block, combined with the blast wave of the synchronized detonation of the high-explosive tiles adjacent to the perimeter walls, buckles and breaks the perimeter columns and initiates the descent of the entire upper block of the Tower.

Stage 2B: Progressive Distributed Blasting Obliterates Tower

Once descent of the Tower's upper block begins, the thin-film explosives on the equipped floors are detonated via the wireless control system just ahead of the descending wave of destruction below the crash zone, as well as in the upper portion of the descending block.

Because the thin film explosives detonate rapidly and have relatively high brisance, the tiles in a given ceiling create largely planar blast waves that attenuate very little until they encounter a floor. The blast waves from one level of tiles travel up to through the web trusses and to the steel pans under the floor slab above, and down through office furnishings to the floor slab below. The fact that the explosive tiles are present only in every other story assures that the detonation of the tiles on one level won't immediately disrupt the tiles on the next lower level, which will be detonated a fraction of a second later.


Copyright (c) Jim Hoffman and 911Research.WTC7.net 2009