7/28/10

Tracking Powder

Ideally I would like to get a radio transmitter for tracking my high-altitude rockets (like Stinger, my high-power L1/L2 certification rocket) but unfortunately I don't know anything about it (even though I have my ham license now). In the meantime, I think the chances of successful recovery could be greatly increased using tracking powder. This can be as simple a stuffing flour or crushed up chalk into the drogue 'chute bay.

I recently tested this idea in a small low power rocket. I think it worked. I never would have seen the deployment if it weren't for the bright white puff that appeared out of no where in the sky:





BY THE WAY:

What kind of a rocketeer works out of a Smart Car?
Also, I will not be going to anymore NAR launches any time soon! They wouldn't let me fly Exporter 3000 (the rocket with the 2 G's cluster) because they said it was equivalent to H impulse, which you need to be L1 certified for. I know, however, that you can fly a cluster rocket up to 320 Ns of impulse and 4.4 oz. of propellant before you are certified. I didn't have a copy of the NAR Safety Code on me or I would have shown them. They didn't remember the rule. I was frustrated. But oh well.

8 comments:

R2K said...

I use street marking chalk for this purpose. However, it can be messy and frankly most rockets dont need it. But for really high altitude rockets I do use it.

http://toolmonger.com/wp-content/uploads/2007/04/post-irwinchalk.jpg

I use red or blue (red for clear day, blue for cloudy day.)

The EGE said...

DO NOT use flour. Get it in the right concentration during ejection, with the flame, and it can explode. Melts your paint. might set your chute afire. Always use chalk powder. Get a big cheap bottle of carpenter's chalk for 2 bucks at the hardware store.

The EGE said...

A few questions about your intended flight. Please answer these *before* reading my next comment.

What motors were you planning to use?

What igniters? How would you connect them?

What's your margin of stability?


If only one motor ignites, will if be stable despite the off-center thrust? Will the single motor lift the rocket to a safe altitude?

What happens if one motor ignites a second after the other? Three seconds?

Have you flown clusters before? Composite clusters?

The EGE said...

Warning: long comment ahoy.

Yes, technically, a cluster of 2 Gs is allowed for uncertified persons at an NAR launch, provided that the total propellant is not above 125g (i.e, no using G75J or G75M with propellant masses over 62.5g each), and some other restrictions.

BUT: an average L1 cert uses a baby H like the H128W, with between 160 and 180 Ns of total impulse. If you're using 2 G78s, say, that's 220 Ns, which is a rather larger motor.

Plus, in a cluster, you've got lots of problem sources. One motor fails to ignite, you've got a 2-pound rocket cartwheeling across the grass. And 2 motors means more aft weight - requiring more nose weight - and twice the chance of a CATO. This is a substantially more difficult rocket to launch than your average L1 bird.

Were I an RSO, I would not allow an uncertified flyer to fly a twin-G cluster unless that person had already demonstrated a great deal of ability in flying large mid-power rockets and flying composite clusters. And flying composite clusters is very very difficult.

I would also want to see that they had designed it for instant-on ignition of both motors. CTI reloads preferred, and either well-dipped or propellant-boosted igniters if using AT loads or SU.

Unless they had evidence that they knew exactly what they were doing, I would not let them fly even if certed, but I would be much stricter for someone without certification.

And remember. The RSO's word is law. You can ask a more favorable person to discuss with the RSO, but they have the final say, because at the end of the day their first priority is safety.

The EGE said...

Also, consider a few other things:

I would not abandon NAR launches just because of this one thing. You can learn so much more at an NAR launch with experienced flyers. They can help you with everything from assembling a reload to picking up the pieces.

If you do fly something that goes wrong at an NAR launch, you will get snarky comments from the RSO for a while. Most will be funny and not mocking. If you fly this on your own and something goes wrong, you're some lunatic causing trouble in the park, and the locals might not be so friendly towards any rocketry in your vicinity, organized or not. Don't get your NAR section run out of town.

Also, for any rockets greater than 1 pound or with more than 4 oz (113g) of propellant (read: most twin-G clusters), you're required to follow FAA rules, and if might be very difficult to get a waiver without being at a club launch.

R2K said...

I would not skip NAR launches because of this, but I agree they were wrong and you are correct about this. Say no for other reasons, listed above, but not a wrong answer about the H impulse thing.

Anyway, DTH is experienced enough I think he is fine to fly cluster G motors. Or at least cluster F motors, as a compromise?

I was flying G55 rockets with 4 D12 motors before getting certified, as well as G125s. I am pretty certain these things were actually not allowed, but it happened. And no one died, and I was younger than DTH at the time.

DTH Rocket said...

EGE--I was not meaning that I would abandon NAR for flying on my own, I was meaning that I would abandon NAR for Tripoli. I've attended both launches and I've found that the Tripoli people tend to be more friendly. Perhaps I shouldn't generalize so much, but nevertheless, that's been my experience.

My Dad just handed me some fluorescent orange chalk-line chalk the other day. I think this will be perfect. Yeah, I've seen first-hand how flour can burn. My chemistry teacher did a demo on particle size vs. combustability, and flour is a very fine particle.

About the cluster rocket: I've flown it before. It has successfully flown three times on 2 G64's. Now, G80's may be a bit trickier because Blue Thunder is a faster burning propellant. If one lights a fraction of a second before the other, it's gonna GO.

1. I use Aerotech FirstFire Jr's and attach wedges of Blue Thunder propellant to them so that there's more contact between igniter and propellant.

2. I coil up some extra wire beneath the pad so that the rocket can lift ~15 feet of the pad and still have a chance to fire the other igniter, just in case.

3. If one motor does not light, provided it is not a windy day, the rocket *should* fly fairly straight only with a lot of corkscrew. However, I recently shortened the body tube so it might be a little bet more at risk of becoming unstable if only one motor lights.

Yes, I recognize that the RSO still has the right not to let me fly (that's why I tried not to argue back) but I DIDN'T like his reasons. I wish I had asked somebody for a copy of the Safety Code so I could have shown him what I was talking about.

Have you flown clusters before?

(BTW, the tracking powder thing was primarly something I was planning on using in my L1/L2 certification rocket, not Exporter. Stinger is supposed to go 5000-6000 feet, and without a tracking device, I'm afraid it will go right out of sight and be lost. Maybe I should add some mass to it or something. Hmmmmm)

The EGE said...

Okay, thanks. I had no idea you'd launched that many cool clusters.

Propellant-boosted igniters are definitely the way to go. I've got a grain of White Lightning from an old SU motor that catoed, but I've heard Blue Thunder is better.

I have flown a few blackpowder clusters. 2, 3, and 4 motors; I'm planning to try 5 A10s next. Once I turn 18, I'm getting some Green Monkey cases and playing with those for clusters.

Be careful to resim your rocket before adding weight. In a lot of cases, extra weight can actually make it fly higher.

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