Go Fever (Patreon)

This week has been kind of garbage, Scout has failed to lift off 3 days in a row now. Generally, that's not a good thing, but I think we can use it as an opportunity to learn.

The first attempt was on Tuesday evening, Jan 15. On the first launch attempt the pad failed to light the ignitor at T-0. With an unknown cause at the launch site, I changed the ignitor and tried again. After a second failure to ignite, I swapped the ignitor one more time and tried again, still to no avail, so the site was packed up and I went home. The attempt on the 15th failed due a fried resistor in the pad ignition circuit, specifically on pyro channel 2 of the Impulse launch computer. The resistor fries when a short circuit occurs for more than a few seconds, it's sort of like a fuse to protect the rest of the electronics. The short term solution is better pre/post flight checks, the long term is better electrical engineering on the pyro channel itself.

The second attempt was on Wednesday evening, Jan 16th. Once again there were 3 attempts at ignition, all of which failed. After attempt 3, the launch was scrubbed. Once again all the equipment was packed up, and I headed home. Upon further testing and analysis, attempt #2 was determined to have failed because of a short between the ignition leads coming out of the computer. This was likely also the root cause of the fried resistor on attempt #1. Again, the fix here is the same - better checks in the short term, better engineering in the long term.

For the third attempt on Thursday, Jan 17th, the car was once again packed and I headed out to the launch site. The forecast predicted a 17% chance of rain, but upon arriving at the site and waiting for a while, the rain wouldn't let up.

Each one of these attempts costs time and money. Because of the cold weather, I burn about 8 heat pads per attempt to keep the cameras on and warm, their batteries die far too quickly in the cold. Each attempt requires about a full day of prep as well, so other work cannot be done. I don't mean to complain, the point here is that there's tremendous incentive here to make irresponsible decisions at the launch site.

When the stakes are high, especially on later attempts after several failures, it's really tempting to push forward despite anomalies or problems on the pad. I could have rigged up a car battery to the ignitor, I could have put a blanket over the rocket in the rain until it was time to launch, there are usually sketchy ways to solve problems on the pad and 9 times out of 10 they're bad ideas that seem fine in the moment. 

Some of this is overkill for model rockets, but the point here is that it's almost always better to scrub and wait another day than it is to blindly push forward. Nearly every time I've tried to come up with sketchy launch-day solutions to a problem, they've failed. This is sometimes referred to as "Go Fever" in the orbital launch industry, and it's something many rocketeers end up experiencing. 

There's no cool engineering here, just wanted to provide a quick update and some thoughts on keeping things safe at the launch site. We'll get Scout flying soon!

Blue skies,

Joe