The Story Behind the Unique Photo of the SR-71 Blackbird Creating ‘Fireballs’ during Air Fete Air Show 1986 at RAF Mildenhall //
During that pass we had “13 fireballs” come out of the SR-71’s exhaust. It looked beautiful, and people wanted to know if it could be done again,’ former Blackbird RSO, Lt. Col. Doug Soifer. //
The maintenance people figured it was the TEB [triethylborane] shooting out of its container and igniting the JP-7. With that start, we had an exciting six weeks in England.’
The SR-71 burned JP-7 fuel. A one-of-a-kind fuel that used an additive to raise its flash point so the fuel would not break down at extreme temperatures. In an emergency situation, crews were authorized to refuel with JP-4 or JP-5, however, this limited the aircraft to Mach 1.5. These emergency fuels were to be used only if the crew was low on fuel and had to use any tanker he could find to avoid the loss of the aircraft. //
To ignite the JP-7 for engine start, and to light the afterburner section, a liquid chemical ignition system was used. Talk about “unique!” The liquid chemical, triethylborane (TEB), had the physical property of exploding when exposed to air. Mounted on each engine was a sealed tank, inerted with nitrogen gas and filled by maintenance with 600cc of TEB prior to each flight. During engine start, rising fuel pressure in the fuel control signaled the ignition system that a metered amount of TEB could be injected into the engine combustion section, after the pilot moved the throttle from cut-off to the idle position. Preceded slightly by fuel, the TEB exploded and ignited the JP-7. Anyone watching an engine start from behind the aircraft could see the tell-tale green flash of the TEB exploding, igniting the engine.
Each time a throttle was lifted up and moved forward into the afterburner range, another metered shot of TEB would light the AB fuel. Each engine’s tank contained enough TEB for at least 16 metered shots to light either the engine or afterburners
