Static Fire

Disambiguation: This article covers vehicle static fires, for engine static fires at McGregor, see [to be inserted].
A static fire is a vehicle ground test conducted in which the respective vehicle is partially fuelled and at least one engine is being ignited for a small duration. The vehicle however stays firmly bolted down to the launch mount, thus the test is called "static". Static fires are common in the space industry in order to check the whole pre-flight process and detect any potential issues, especially of the engines, that need to be addressed before a flight attempt. As SpaceX, unlike for example NASA, doesn't use flame diverters, it can only conduct short static fires up to some 2-3 seconds. A longer duration would increase the risk of damaging the engines, for example through rocks and dust.

After Ambient Pressure Tests and Wet Dress Rehearsals, Static Fires are usually the third type of pre-flight ground testing that is conducted on a vehicle. However, especially with early test programs, a Preburner Test was usually conducted before a Static Fire. A successful static fire is beliefed to be the final step (on the vehicle side) necessary in order to make a flight attempt.

## Testing objectives

Static fire tests are tests, where whole process from fuelling up to ignition is being conducted. They are intended to check whether the whole system is working, including ground equipment, external and internal plumbing, vehicle, and engines.

Special attention is given to the engines, as this is the only test where they are ignited. If an engine doesn't return nominal data, it is usually swapped out before a next static fire test.

## Typical timeline

### Requirements before testing

Before SpaceX can start a static fire test, it needs to meet the following requirements, that can also be used as indication for a potential static fire:

* Road closure announcement on the Cameron County website, usually at least one day in advance
* Alert notice issued to the residents of Boca Chica village, informing about the potential risk of an "overpressure event that can break windows", usually issued in the evening before a planned static fire
* "Temporary" Flight restriction (TFR) to an altitude of 5000 feet, always in place

### Testing day

The following timeline is an approximation of a selection of major events that happen on a static fire test day. As this is an experimental test program, the timeline is always subject to change. Furthermore, wheather can obstruct views so it might impossible to detect a certain vent.

* Road closure (See Sentinel cam from LabPadre)
* Beach clearing (Look out for Sheriff going to the beach area)
* Pad cleared (No cars and people at the launch site, look at Launch Pad cam and NSF stream; usually the Sheriff car and a SpaceX Tesla leave the pad as last)
* Satellite antenna lowered (Seen on sentinel cam)
* **Recondenser** start as indication that activity is starting (Seen on Nerdle cam and NSF; white puffs of clouds coming from behind the three smaller black water tanks)
* Ground vent (Sometimes seen on Nerdle and Launch Pad cam, no clear time indication, often also the first vent to be seen)
* Farm venting (Venting activity on the tank farm spooling up, acutal vents sometimes visible on NSF stream)
* **Skirt vent** (Puffs from underneath the skirt, visible on Launch Pad cam and NSF; indication for propellant load, fuelling)
* **Methane** vent (Vent from the middle of Starship, approximately in the area of the CH4 tank, sometimes there is a small vent first and a big vent later)
* **Tri vent** (Engine chill, usually three vents coming out from the skirt section, can be single or double vent if not all engines are ignited, the best time indication)
* Header vents (Only if header tanks are filled with fuel)
* **Static fire**
* Double depress vent from LOX and CH4 vent (if immediately after SF, indication for potential problems, if some 30+ seconds between SF and depress vent, more likely to be successful)
* Continuous depress vents
* Road opened

### Time to T-0

There are several indications for the time left until T0. However, there could always be holds during the process or potential scrubs:

* Condenser: 36-46 minutes
* Skirt vent: 20-29 minutes
* Methane vent (the big): 16 minutes
* Tri vent: 11:52 to 12:15 (usually)

For more accurate estimates, consider Adrian Beil's twitter account. He tries to find accurate timelines.

## History

The first vehicle to undergo static fire testing was Starhopper on April 03, 2019.

[to be continued]

It is expected that a fully reusable Starship wouldn't need to conduct static fire tests anymore.