Comments on: Build a $5 Heli-Rocket from MAKE Volume 25 http://blog.makezine.com/2011/01/20/build-a-5-heli-rocket-from-make-vol/ DIY projects, how-tos, and inspiration from geeks, makers, and hackers Thu, 23 May 2013 09:12:34 +0000 hourly 1 http://wordpress.com/ By: RocketGuy http://blog.makezine.com/2011/01/20/build-a-5-heli-rocket-from-make-vol/#comment-207228 Wed, 30 Nov -0001 00:00:00 +0000 http://makezineblog.wordpress.com/2011/01/20/build-a-5-heli-rocket-from-make-vol/#comment-207228 Don’t ever use fuse to light a model rocket. It’s against NAR regs, but mostly, it’s against the regs for a reason.

Fuse is not as reliable as electric ignition, and there are many ways to go horribly wrong with it.

If you miss with your flame source, it’s even possible to ignite your engine without a delay, which isn’t the brightest thing you can do.

And if it misfires, well, it’ll probably ignite just as you’re reaching down to fix it.

So while I’m glad the project went well, this is really not a good example of how to launch a rocket.

The NAR safety record stands at several million launches with no major injuries or deaths, so at least read the regs for reference/guidance even if you don’t follow them all to the letter.

Happy Skies-
-RG

]]> By: Tester http://blog.makezine.com/2011/01/20/build-a-5-heli-rocket-from-make-vol/#comment-207229 Wed, 30 Nov -0001 00:00:00 +0000 http://makezineblog.wordpress.com/2011/01/20/build-a-5-heli-rocket-from-make-vol/#comment-207229 The assertion that the igniters are less risky than fuses is dubious. In my 30+ years of rocket launching, the only time I have seen problems are with igniters. I have personally witnessed armed launch pads toppled over when the wires were inadvertently pulled taught by the guy launching. That doesn’t happen with a fuse. Far more likely, the electronic system is unintentionally left armed (or placed in the armed position) when people are at the launch pad connecting the alligator clips. This is more common issue with multiple launches. Even with sophisticated launchers built with a key switch and red-guarded arm switch, a dad forgot to take the key out, and a kid reached for the arm switch. Thank goodness for the audible alarm- almost none of which are in kit systems (see http://makeprojects.com/Project/10-Rail-Model-Rocket-Mega-Launcher/243/1 ). With fuses- the fuse-lighter is in complete control of the ignition phase. Sure the fuse could be too short, but that’s a human error issue, just like leaving the safety pin in an electronic launch box. I’ve also seen many people (I’m one) approach a pad that had a shorted igniter with a system armed — less likely, with a burning fuse, but still possible.

As a US Navy Test pilot, I have been well schooled in risk assessment and risk mitigation. The most dangerous part about these clips is the drive to and from the launch site. Second riskiest was getting in and out of the shower. To reduce risk, should we drop the highway speed limit to 25 mph? How about 5 mph — that would be even safer! We cannot eliminate risk, but can be aware of the consequence and likelihood.

Seriously, does anyone think that NASA can get to the moon with the incredibly risk averse climate today? If we had this attitude in 1969, the entire moon program would have been canceled after Apollo 1. Remember when kids went outside today, instead of having “playdates” scheduled, under total parental control? The number of kid abductions didn’t change — risk attitudes, and the new desire to drive risk completely out of our lives changed.

Everyone should launch how they deem “safe,” and I’ll do the same (I’m not a member of NAR or Triploli). The danger level in these clips is very low, and arguably as safe as a standard ignition system, with my overall experience in understanding risk.

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