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Basic questions.

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Wrangorocket

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A few basic questions.

What do I need to understand if/when I decide to use a motor with a higher impulse? Think Estes Ricochet, I noticed a C-6 fits nicely! I know to use streamer recovery instead of a 'chute for the extra altitude. Do things like nose weight and the "swing test" come into play?

BTW, what is the swing test. I'm no rocket surgeon! :eek:

On my Taser Two, what is going to hold the 1st stage onto the 2nd? Looks like friction is all there is. No feather weight recovery for the first stage? I'm assuming the spent motor will still be in the 1st stage? I understand it will be much lighter but would rather the motor just fell out for the sake of the fins.

Would someone show me their home built launch system? I need some ideas for materials. It has to look good, my Grandson has got to get a kick out of it when he launches. I remember the feeling of "seriousness" when I launched with my Dad when I was about his age. The system my Dad built had a key, arming switch, armed light and a launch button. Very cool! I asked him the other day if he still had it and he gave it to my little Brother years ago. Funny, I don't remember him even getting into the rocketry thing!

Oops! Just looked at the glossary of terms! Geez, nooby!
 
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shreadvector

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Almost everything is located in the "sticky thread" at the top of this forum.

The answer to the Taser question is in the "Classic Collection" in the multi-stage rocket section.

Take a little time and read through as much as you can and compile more questions. If you can't find the answers in the massive resources listed, post them here and we will point you to the answers.

As for a launch system - building them is fun but you need to make sure that if you use a key type removeable interlock (ALL systems need a removeable interlock), that you choose a key switch that can only have the key removed when it is "OFF". If you can remove it when "ON" (like with an alarm system key switch) it will be fundamentally dangerous and violate NFPA fire code.
 

Wrangorocket

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So something along the lines of an automotive key to turn master power on and then an arming switch?
 

shrox

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So something along the lines of an automotive key to turn master power on and then an arming switch?
That could work, but much more complicated that it would need to be. Most launch "keys" are just something that bridges a gap between two contacts.
 

shreadvector

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So something along the lines of an automotive key to turn master power on and then an arming switch?

Basicly. there are simpler keys, similar to the basic alarm system key but that only allow the key to be removed when "OFF".

Google it.


BAD: http://www.amazon.com/dp/B0002BA3PE/?tag=skimlinks_replacement-20

GOOD: http://electricbikeparts.manufacturer.supplierlist.com/detail126621-electricscooterkeyswitch.htm (I did not check the voltage and amperage rating on this one, but you get the picture - key removeable only when OFF)
 
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shreadvector

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That could work, but much more complicated that it would need to be. Most launch "keys" are just something that bridges a gap between two contacts.

Yes, you are correct, but in his original message he longed nostalgically for a complex looking overly elaborate controller with a key like his dad built.

A Quest controller would be perfectly fine for most. A Quest controller with EBC would be beyond perfectly fine for almost everyone. But, he wants a key.

Of course, the Quest controller beeps and blinks like a Star Trek device. I'll bet that Dad's did not. :neener:
 

Zeus-cat

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You could go with a switch guard and a momentary switch. You have to lift up the guard and then push the spring-loaded toggle switch forward to launch. It snaps back and turns off if no pressure is applied (assuming you wired it corectly).

RedSwGuard.jpg
 
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Wrangorocket

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That's what I was thinking Zeus cat. I'll bet I can rig a simple keyed switch and then put a light in line then the momentary switch you show above. I'm gonna make a really cool launch controller. He'll love it! :D
 

luke strawwalker

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That's what I was thinking Zeus cat. I'll bet I can rig a simple keyed switch and then put a light in line then the momentary switch you show above. I'm gonna make a really cool launch controller. He'll love it! :D

Don't bother using a light... use LED INDICATORS from Radio Shack-- that way your system will be safe for low-current ignitors like the Quest Q2G2's, which are really great little ignitors and perfect for clustering as well as igniting 'ordinary' rockets. Radio Shack is also a good source for push button momentary ignition switches, guarded switches, and other electronic goodies as well. I also use some switches from the auto parts stores as well for certain things, but Radio Shack has an excellent selection. Some stuff IS cheaper at the auto supply though... :)

Anyway, there are also some threads about upgrading your Estes controller into something a lot more capable (and cool) if you want to look them up, either here, on Ye Olde Rocketry Forum, or Rocketry Planet as the case may be. I know we had a good in-depth discussion recently on this at YORF.

Good luck! OL JR :)

PS. As for staging, don't worry too much about the lower stage fins-- they should be fine. You really don't want the casing coming out-- it's not necessary and could possibly pose a falling object or fire hazard. Lower stages are usually pretty unstable and tumble coming down, and they don't get that high anyway, not like a rocket 'falling from apogee'. If you're worried about busted balsa fins, you can always "paper" the fins by gluing on a layer of printer paper-- this strengthens them enormously and also makes them nice and slick for painting-- no more filling and sanding balsa grain! I usually harden my balsa fins by wicking in thin CA glue on the surface-- this glue soaks into the wood and turns it into an almost 'composite' type of material far harder than the bare wood. I also do this on balsa nosecones. Be sure you do it outside, though, because it does give off some strong fumes as the CA soaks into the wood. I use ultra-thin CA glue from Hobby Lobby in the pink bottles for this, and it works great.

As far as your original question about the rocket, for LPR stuff subbing in a larger motor should be fine. Most kits (especially) have enough built-in stability margin to accept the heavier motor (unless the kit says "such-n-such engine ONLY" in the instructions or packaging, and that advice is usually best heeded!) because they know EVERYBODY wants to cram the largest impulse engine they can possibly get to fit in the kit in the rocket at some point. Scratchbuilt homemade designs can be a lot more finicky on their stability margins and that's why a swing test is always a good idea. To do a swing test, just make a loop on the end of a 10 foot-ish piece of string, and balance the rocket in the loop until it's level (this puts the loop at the Center of Gravity (CG) and tape the loop in place, then swing the rocket around your head in a circle. Note: this is with the rocket essentially 'flight ready' with the motor, parachute/streamer, and recovery wadding in place, but no ignitor) If the rocket points in the direction of 'flight' as you're swinging it, it should be fine. If not, add a bit of weight to the nose (usually clay works well) as far forward as you can (usually inside the nosecone if it's plastic, or under the screw-eye at the base of the nosecone if it's not, like using a washer or two), rebalance, and try again. You can also use rocketry computer programs like RockSim from Apogee Components for this, as you can 'build' the rocket on the computer and then it will calculate the CG and Center of Pressure (CP) for you and tell you the stability margin. You can also 'test fly' the model using various engines, parachutes, streamers, etc. and select different wind conditions, launch rod angles, etc. to see how changing things affects the rocket's likely flight. You can download a trial version at www.apogeerockets.com

Any other questions we'd be glad to help! OL JR :)
 

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