# What is the function of this Merlin engine's tube, and why is it getting red hot?

In the video of the recent SpaceX Starlink launch, one view of the Falcon-9 2nd stage engine shows a cane-shaped tube that glows red hot at the "handle" end and seems to get hotter over time.

Question: What is the function of this tube, and why is it getting red hot?

The first two images are from T+04:19 and T+07:38, you can see here and in the video that as the tube heats up the red glow moves from the "handle" of the cane only and starts down the body.

The next two views are different lighting from the Sun to better understand the tubing and geometry.

• That rams-horn shaped thing is almost certainly where the drive gas exits from the turbine. The J-shaped tube seems kinda small, so it's probably ignition system related or a feedline for the gas generator. All guesses, of course. There's a side view in this answer: space.stackexchange.com/a/25925/6944 – Organic Marble May 26 '19 at 1:21
• @OrganicMarble to me all engines look like some version of this: space.stackexchange.com/q/30598/12102 similar to what car engines looked like after all the emissions control tubes, wires, sensors, valves and gizmos were added. – uhoh May 26 '19 at 1:34
• I could answer the red hot part: because it's connected to a running rocket engine :) Of course there are other parts that aren't red hot. – Organic Marble May 26 '19 at 1:35
• This picture seems like it has some explanation on it but because of company proxy I'm unable to open it in full resolution. For my understanding are those the same long bendy pipes as on this picture? – GittingGud May 28 '19 at 6:41
• @GittingGud I'm not comfortable with tiny urls. Can you show the real links to the sites you are looking at? Thanks! – uhoh May 28 '19 at 6:42