Time Delay Initiators
Time Delay Initiators (TDIs) are used to properly sequence events in a system. They are used in emergency egress, missile, and spacecraft systems. The description provided in this section will focus on aircraft Emergency Egress Systems (EES). TDI’s can accept both hot gas and detonation inputs to initiate and provide likewise as an output. Our TDIs have been incorporated on ejection seats and within CRS / TRS and canopy jettison systems. Examples of our TDIs are illustrated below.
T-6 TEXAN II
F/A-18 HORNET, TAV-8B HARRIER, T-45 GOSHAWK
F/A-18 HORNET, T-45 GOSHAWK
TDIs are initiated by hot gas pressure, output from an ETL HE End Fitting or mechanical. Upon receipt of a gas, detonating or mechanical pull signal an annular firing pin releases and is driven into dual percussion primers. The primers fire and ignite the delay element called Small Column Insulated Delay (SCID). After the SCID has burned for its allotted time it ignites a gas generating charge or high energy transfer charge output. The gas output flows from the bottom of the initiator through a filter into the ejection seat and attaching sequencing system. A detonating output fires an attached ETL.
SCID is used to provide a time delay tolerance of approximately ±15% maximum across the operating temperature range of -65°F to +200°F for EES’s. To ensure the proper TDI is installed into the proper position a combination of different anodized / painted body colors and various thread sizes are used to identify individual units. Mounting provisions to secure the TDI are machined into the initiator mounting flange.
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