Day in the Life Series: Hot Fire and Cold Flow Wrap

Here’s a recap of every “day in the life” post on hot fires and cold flows to date.

Up next, another interview from the bunker. Stay tuned.

A Day in the Life of a Hot Fire

Part One: Morning prep and checklists

Part Two: Caravan

Part Three: Bunker and Test Stand

Part Four: Roles

Part Five: Hot Fire!

A Day in the Life of a Cold Flow

Part One: Roll out and tank fill

Part Two: Bottle Trailer

Part Three: Setup

Part Four: Cold Flow in Action!

A Day in the Life of a Cold Flow, Part Four: Cold Flow in Action!


After running through LOX fill, setup, and pressurization checklists, the cold flow commences with a beautiful stream of liquid oxygen flowing from the engine. Flow rates and temperatures are recorded and checked both in real time and later during a data review. Functionality of the entire system is evaluated. If necessary, more flows are conducted, or the system is prepared for a hot fire test in the coming days.

Tune in this weekend and we will update you on where to find XCOR on the road (and online), and an update on how we will answer more of your questions in the coming weeks.

As always, ping us on Twitter or Facebook with your comments, or leave a comment right here.

A Day in the Life of a Cold Flow, Part Three: Setup

So we’ve covered the rollout and bottle trailer, today we’ll show you a bit about the cold flow setup.


Geoff Licciardello acts as control, Jeremy Voigt reads checklist, and Lee Draper and Dale Amon perform Data Acquisition. More on the specifics of each role can be found here.

Instead of a control bunker, a table is set with the same control box and data acquisition setup we would have for a live hotfire. Since cold flows are close by the hangar, crews larger than those at a hot fire can participate in discussions between flows.

04_WED_2_12-09-12_90sec-coldflow-8648XCOR CEO Jeff Greason keeps a keen eye on the test for any sign of a problem.


A number of XCOR staff discuss the results of a cold flow and decide what to do next.

Tomorrow, experience the cold flow!

Questions or comments? Hit us up on Twitter or Facebook, or in the comments section below.

A Day in the Life of a Cold Flow, Part Two: Bottle Trailer


Jeremy Voigt (Control) and Ray Fitting (Red Team) are shown maneuvering the test stand into position with a hitch dolly.

The bottle trailer is a test stand we use to supply our valves and tanks will pressurization gas. The trailer holds 10 gaseous helium tanks and 8 gaseous nitrogen tanks. It also carries a standalone gaseous nitrogen sphere that bypasses the normal test stand plumbing for use in and around the hangar.


Ray Fitting opens one of the valves on a bottle trailer tank.

The idea behind the bottle trailer is similar to that of XCOR’s other test stands.  We needed a mobile platform that could be versatile and make our pressurization gasses available wherever our testing might be conducted.

After LOX fill, the stand is moved into position in front of the hangar doors and the bottle trailer is rolled up next to it.  Plumbing lines are connected between the two test stands and we are ready to get underway

Tomorrow: join us as we set-up for a cold flow.

Questions or comments? Connect with us on Twitter or Facebook, or connect with us below.

A Day in the Life of a Cold Flow, Part One: Roll out and tank fill

We ended last week with a hot fire in action. This week we’re going to chill, and show you a “day in the life” of a cold flow.

Your questions and comments matter to us, so comment or ask us anything on TwitterFacebook or right here on the blog.

So “what is a cold flow”, you ask? A cold flow is a test where fuel or liquid oxygen is moved through the plumbing system as it would be during a real engine test without lighting the igniter. The point is to serve as a final check of plumbing and valves before a hot fire. This allows us to find and fix minor leaks and valve reliability before heading all the way out to the test site.

The day of a cold flow begins much like the day of a hot fire. First, the stand is rolled out, checked and then moved to the large stationary LOX dewar (tank) for fill.



In the top photo, Geoff Licciardello reads the LOX fill checklist while senior engineer Mike Valant handles the fill hose and senior technician Mike Laughlin observes. At bottom, Derek Nye, Geo and Jeremy Voigt make further preparations in advance of a cold flow.

If the cold flow will be a test of the fuel system, kerosene will be loaded from storage barrels using an electric pump.

When flowing liquid oxygen during a cold-flow test, the LOX is pumped out into the atmosphere (into the air) where it evaporates instantly and becomes gaseous oxygen. When flowing fuel during a cold-flow test (never done at the same time as LOX), the fuel is pumped into a closed fuel container to be re-used.

As you may have guessed by now, a cold flow has the added advantage of happening right outside the XCOR hangar. In this series we’ll showcase a liquid oxygen cold-flow happening just outside the hangar doors.

Tomorrow we roll out the bottle trailer!