What do we need to know for our first model rocket launch?

September 17, 2009 6:22 AM

What do we need to know for our first model rocket launch?

My seven-year old son, six-year old daughter and I will be making our first model rocket launch this Saturday (using an Estes taser launch kit). We've seen this question, but I had a few specific questions about what to expect when we go out, and would like to know if there's anything else we should know. We're aiming to do maybe 8-10 launches.

We're pretty familiar with safety regulations, and have a great open field lined up at which we'll be conducting the launches. Here are my specific questions, but if anyone else has anything we should know going into this, please feel free to chime in:

1) This rocket is rated for up to Class C engines. I'd like to start with some smaller engines (1/2A, A) if possible -- how do we secure them inside the rocket? Wrap tape around them? Does it need to be a tight, secure fit, or a loose fit like the parachute?

2) What should we have in our "launch kit?" We have scissors, a model knife, glue, safety goggles, a fire extinguisher, extra batteries, and duct tape. Anything else we might need to reduce contingencies that might cut our day short?

3) Do we need to buy extra igniters, or are the ones that come with the engines sufficient?

4) In the (hopefully very unlikely) event a fire extinguisher is needed, will a standard class A/B/C extinguisher do the trick, or do we need a class D?

posted by Doofus Magoo to sports, hobbies, & recreation (17 comments total)

1) A is the same width as a C engine so you should be okay with the supplied clip
2) You sound much more prepared than when my boy and I did it earlier this year!
3) We found the ones supplied were sufficient
4) Unknown - I didn't have one.

The one thing I will add is to use a streamer or cut a really big hole in the parachute so that it lands relatively close to the launch point (I prefer the streamer) use the A engine to determine how the wind is blowing, and then move up to the B's and C's.

Have fun!
posted by zeoslap at 6:34 AM on September 17

The engine should be tight, but you need to be able to remove it, in our kits, the engine was either locked in place by the tail assembly, or was in a small cardboard tube with a clip on it at the bottom.
posted by zeoslap at 6:36 AM on September 17

(It's been around 26 years since I launched any model rockets)

1) Hmmm, I thought they were pretty much all class C engines, but offered in different sizes. I never tried adapting a rocket meant for a larger engine to use a smaller one, so I can't tell you the best way to do it. I'm doubtful that it's a good idea. In any case, the engine absolutely must fit tightly into the rocket. It also must be lined up precisely with the axis of the rocket unless you want to propel it in an arc into the ground.

2) Maybe some extra parachute cord in case of irreconcilable tangles? Wire cutters / crimpers and extra alligator clips in case the launcher gets damaged?

3) I would bring some extras.

4) I doubt you need a fire extinguisher at all unless you're launching in a grassy area of southern California.
posted by jon1270 at 6:36 AM on September 17

It’s been a while since I launched a rocket but from what I remember:

1) You should be able to buy adapters for smaller engines at hobby stores. You can use tape but you have to be very careful that the engine sits perfectly straight in the socket. Otherwise the rocket won’t fly straight.

2) That’s probably plenty. Maybe a needle nose pliers for taking out expended engines. They’re usually still hot to the touch after a launch. Some extra wadding if your rockets use parachutes. A watch with a second display might be fun to help the kids count down.

3) Bring a few extras. Sometimes the igniters fail or if they’re not seated correctly in the engine they won’t light the engine.

4) Unless you’re launching a rocket in the middle of some dry scrub, a few stomps with your sneaker will be plenty. Bringing a fire extinguisher is probably a good lesson in responsibility for the kids but, in my opinion, is overkill.

Some other things to think about:

Don’t underestimate just how high and far the rocket will fly, especially one with a parachute. I don’t think I ever launched one more than twice before I lost it and they can be hard to spot when they get up high. Drop a few blades of grass in the wind to judge the direction and set up your launch pad so you have plenty of field downwind. Warn the kids ahead of time that there’s a very good chance you’ll lose the thing.

Record the launches on video if you can. This way any crashes won’t be as disappointing because the kids will have awesome video to show for it.

Have fun.
posted by bondcliff at 6:42 AM on September 17

Definitely use the same diameter engine as is recommended. The rocket kit should have a list of recommended engines; start with the smallest one on the list. That was always my biggest mistake when I was launching rockets - got the biggest engine I could find and lost the rocket on the first launch.

Set yourself up based on the prevailing wind, because the parachute will really carry the rocket body. So if the wind is blowing east-to-west, set up near the eastern border of your launch area so you have maximum clear space for recovery.
posted by backseatpilot at 6:44 AM on September 17

Oh, and the launch pad you have with the kit should have a big metal disk that deflects the exhaust away from the ground. That was always sufficient for me to prevent any fires.
posted by backseatpilot at 6:45 AM on September 17

A pair of binoculars may not hurt. If you're quick with them, they may help you with your recovery. Also, be SURE to watch the rocket hit the ground on recovery, and before you start moving towards it, pick out your landmarks. Then walk in a straight line.

Make sure your batteries are fresh.
posted by craven_morhead at 6:50 AM on September 17

Oh, bring sunglasses, hats with visors and shoes for running. The power phase of the launch only lasts a couple of seconds; after that you and the kids will be gazing up into the bright sky trying to discern where the thing is and which way it's headed... and running to meet it.
posted by jon1270 at 7:00 AM on September 17

1/2A engine will not only be too small it won't be powerful enough to launch the rocket high enough to get an idea of prevailing winds above the tree line. Use an A8-3 or B4-2 or B4-4
Here's a link to a PDF listing Estes engine specs.
Needle nose pliars
An extra rocket. This will mitigate the disappointment when the 1st is lost or damaged. (It will be.)
Take the advice above about cutting a larger hole in the parachute or using streamers.
Snacks and water
Extra wadding. There's never enough.
posted by Gungho at 7:13 AM on September 17

1) If it recommends a C engine don't try to use a 1/2 A. Use what is recommended (The lowest on the package first). It should be a relatively tight fit (you want the engine to stay in the motor mount not shoot through the nosecone). Keep in mind that the engine will expand some when launched so if you have to cram it in good luck getting it out for the next launch.

2)I'll just give you what I keep in my standard launch kit

• Scissors, for cutting holes in parachutes
• Streamers, in case the day you pick is too windy for a parachute
• Recovery wadding
• Baby powder, helps with parachute deployment just use a little before you pack it up each time
• Super glue, for quick repairs
• Pliars, for getting the occasional stubborn spent engine out
• Extra igniters, In case you get a broken one, or in case one breaks while kids are trying to sort out the alligator clips (Feel free to use your own judgement here, I was usually launching with a bunch of 4-H kids so kept extra things on hand)
• Spare Batteries
• A pencil or something long to poke recovery wadding around with
• Oh, and if you plan to launch the same rocket many times an extra fin and some Elmer's might not be amiss

3) See above
4)A fire extinguisher seems like over kill here. If you think there is a chance you are going to set things on fire then you should find a different place/conditions to launch. But hey safety is cool so if you want to have one along go for it. For solid model rocket engines, a regular extinguisher would work in theory. In reality, the engine is going to be done burning in a few seconds (as noted on the engine), or explode in a much quicker fashion (and it's not really a firey explosion sort of thing). Your metal splash plate should protect your environment from the engine. Worst case the rocket hangs on the lunch rod and you get a very charred splash plate.

One thing to keep in mind over several launches is that 9 times out of 10 the reason a rocket doesn't launch is electrical circuit related. So, if it doesn't launch check that the clips aren't touching, igniter wires aren't crossing (both outside and inside the engine), and that the igniter tip hasn't broken (you can still make a broken igniter tip work by some careful use of tape).

If your launcher doesn't beep at you when it is armed make sure to keep track of that. That is the safety hazard I see the most among new rocketeers.

A few tips for recovery:
1) In general don't actually try to catch the rocket. I've seen a lot of rockets get stepped on that way. (Plus, you probably don't want to grab the hot end just yet)
2)Keep track of the wind. If you are in an open field you should be aware of the wind once you get above any neighboring tree lines, and also observe any low level cloud behaviour. I like to bring a small simple rocket with a streamer to launch first and test the wind conditions.
3) Based on the wind you should adjust your launcher to point into the wind a bit.
4) Your choice of recovery system should be based on the wind conditions. Unless it is a rather still day I would not recommend using a parachute without a hole cut in it. Your first cut could be the colored area at the top that probably has a dotted cut here sort of line. If that is still too much parachute feel free to keep cutting. Once you are down to about a 2-3" ring of material I'd move to using streamers. (the fastest way to trim a parachute is to hold the center and bunch it up with the center at the top and the strings at the bottom (first step in packing the chute), then cut away as much material as you need)
5)One other important way to control rocket recovery is the time delay between the end of burn out and the ejection charge. On a windy day you might want the rocket to tumble down a bit before it deploys a recovery system. The delay between the end of burn and the ejection charge is the last number on the engine label in seconds. For example a B6-4 engine would have a 4 second delay after the thrust burn before the ejection charge.
6) And this really shouldn't be last on the list, but: Watch the rocket. (I also don't recommend launching near fields of crops because all that leafy vegitation is really good at hiding rockets.)
posted by Feantari at 8:07 AM on September 17 [1 favorite]

Absolutely do NOT use 1/2A engine in a rocket that takes C's. One thing you should see in the instructions is a panel with recommended engines. Most Estes kits have on marked for "first launch" which is usually the weakest recommended engine in the set.

You have a pretty good kit - I like to have an extra pack of igniters. The quality of the included igniters has improved since I was a kid, but if you get a misfire or two, you'll run out.

As for glue, bring a gel cyanoacrylate to repair broken fins. Regular white/wood glue won't dry fast enough. If you really want to fix in a hurry, bring some accelerator like JetSet. I recommend the gel as it's easier to work with on the spot than regular super glue, which is very runny. It makes it harder to glue the rocket to your hands. Hedge your bets and cut two extra fins from balsa (make sure you get the grain direction right - it matters).

Make sure that the kids do NOT try to catch the rockets as they land. This is the second fastest way to ruin a rocket (too tight nose cone/wadding is the fastest, as that turns your rocket into a lawn dart). Teach your kids how to pick up the downed rocket. The expended engine will still be plenty hot.

The rocket parts that I remember seeing fail in terms of frequency are:

1. fins
2. chutes
3. shock cords
4. launch lugs
5. engine mounts (fairly rare)

Estes rockets typically last 3 or four launches at the hands of the young before they need some serious attention.

Bring cameras and take lots of pictures before, during and after. My dad took slides and we had slide shows once the film was processed.

One thing I never did, but wish I had was to pound a stake into the ground near the launcher and tie off the wires to it as a strain relief so nobody accidentally rips out the igniter when they trip on the wires.

My dad built our launch controls (he was an EE) and really tried to enhance the whole rocket launch experience by putting in a safety switch, a continuity tester, an audible warning, and a launch button. I am intending to do something similar for my kids, but I intend to step it up by using a proper arming switch, and I have a couple industrial power switches (meant to throw a breaker to cut off power) that really make you feel like you're doing something. In a pinch, you could substitute one of these.
posted by plinth at 8:18 AM on September 17

An extra rocket. This will mitigate the disappointment when the 1st is lost or damaged. (It will be.)

Seconding this.
posted by Cool Papa Bell at 10:02 AM on September 17

Thanks for the awesome suggestions so far! I didn't realize that the rockets were so "disposable" -- I'll buy a couple of extras, since I managed to procure a 24-pack of engines (an assortment of class A, B and C, plus igniters, and wadding) for $27 today, so we've got a bit left in the budget (woohoo!)

Also, thanks for the pointers about the engine sizes. I thought the sizes that were recommended for that rocket were all different diameters, but on further review, it looks like the 1/2A is where the diameter starts to change, so we're good with the assortment we got of class A, B and C.
posted by Doofus Magoo at 11:00 AM on September 17

NEVER GLUE THE NOSECONE IN PLACE.
ALWAYS MAKE SURE IT COMES OFF EASILY.
NEVER GLUE THE ENGINE PLACE, EITHER.
As taken from here.

Here's the story:
i remember building model rockets when i was younger, and dealing with all sorts of details that went into the launch. my younger brother was into it, too, and i think some of these details were a little too much to bother with.

see, we were super competitive. i remember building a C power rocket one afternoon. my siblings and i were very competitive. the aforementioned brother HAD to build a rocket, too.

of course, he, being the youngest brother, ended up getting shafted in the dough-for-fun-fund. he wound up scrounging enough money to buy the Mosquito, a rocket that used A (AA? AAA? what's the smallest rocket?), and was no taller than a pencil.

launch time was nearing for me, so he set to work at a feverish pace. he soon came out with this hideously spray-painted, still-wet and dripping with paint yellow and black rocket that looked uber pizacrap.

we launched it in front of our house in the suburbs. neighborhood kids came out to watch. he threaded the rocket onto the launching pad, connected the fuse up, and started the countdown.

3...
2...
1...
FWOOOOOOOSH!

sucker flew straight! straight up REAL FAST! all these kids were ooohing and ahhing. even the folks across the street were impressed! the rocket didn't get too high-- it was still very visible when it began to slow down and arc downward.

there's something terribly graceful about a rocket gliding in the air-- it was beautiful. not a peep was heard in the crowd.

so heavenly, so peaceful! we knew that any moment now, the tiny secondary charge would gently pop the nosecone off and unfurl the streamer which would let it fall gently to the ground...

so graceful!

then BOOM! the rocket BLASTED toward the earth at something akin to warp 10. kids were screaming and tried to run away, but it was just too fast! it impaled itself into the ground, several inches deep, still smoking, and then caught fire.

kids were crying. parents were yelling. we began to try to figure out what happened. he glued the nosecone, which is supposed to pop off, into place.

that secondary charge had nowhere to go but out the back of the rocket. and when the back of the rocket is facing up, the rocket's gonna go down. fast.

THE MORAL OF THE STORY:

NEVER GLUE THE NOSECONE IN PLACE.
also, WET SPRAYPAINT IS A FIRE HAZARD.
also, NEVER GLUE THE ENGINE IN PLACE.
also, WET SPRAYPAINT IS STICKY.
posted by herrdoktor at 9:01 PM on September 17

That's a funny story except that the mosquito has no chute - it's tumble recovery - so the nosecone IS glued on. I built one as a kid and got two launches out of it. The first was the low 1/2A, the second was high. It vanished after the second launch - I mean GONE. I think it went through a rip in the space time continuum.
posted by plinth at 8:58 AM on September 18

Thirding an extra rocket. My first launch when I was a kid (Estes Wizard) was cool but the rocket never came back down.

Expect an occasional "lawn dart" (rocket heading nose-down to the ground with a failed recovery system) and don't be standing there when it happens.

Most Estes rockets are massively oversupplied with parachutes. I always cut the middle circle out of the 'chute or, for small rockets, replace it with a streamer. I'd rather have an occasional chipped fin than a rocket that drifts to earth so slowly that it's 10 miles away when it hits the ground.
posted by mmoncur at 7:15 PM on September 18

That's a funny story except that the mosquito has no chute - it's tumble recovery - so the nosecone IS glued on. I built one as a kid and got two launches out of it. The first was the low 1/2A, the second was high. It vanished after the second launch - I mean GONE. I think it went through a rip in the space time continuum.
Doh! Then I wonder what caused it to go bang and shoot down into the ground? Maybe it was another rocket, though I seem to remember it being called the Mosquito.
posted by herrdoktor at 7:19 PM on September 18