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  #1  
Old 06-13-2013, 06:40 PM
Kevin Huddleston's Avatar
Kevin Huddleston Kevin Huddleston is offline
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Default Dual deploy question

I'm a newbie when it comes to dual deploy, but I have a bird (Hyperloc 835) dual deploy ready with all the electronics, etc. I have 2 questions:

(1) I'm using the Aerotech hardware with an H268R motor (not too high, but high enough to test the dual system). Should I just include the delay in the motor build (with no bp charge) or include some kind of cap I need to include to prevent motor thrust up into the rocket resulting in a cato?

(2) I am using shear pins. Two for the nosecone and 3 for the body section for the main. Though I have measured the appropriate amount of black power (about 1.5 grams each) for the respective volumes, should I add a bit more for shear pins?

Thanks!
(Having a hard time finding internet answers for all this...)
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  #2  
Old 06-13-2013, 06:51 PM
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chadrog chadrog is offline
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If the delay is longer than your expected time to apogee, it's a good idea to use your motor eject as backup. If you need a longer delay, let me know. I'm a bit confused by the description of your shear pin setup, but that's irrellevant to the idea of ground testing - this is the best way to know your charges are the right volume. How do you have your pins set up for cardboard? What size shear pins are you using?
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Old 06-13-2013, 07:13 PM
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Kevin Huddleston Kevin Huddleston is offline
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I have 2 shear pins (the tiny nylon screws that Tim sells) for the nosecone -- rogue chute. I have three of the same for the lower section for the main. I thought that since I'm using a dual deploy altimeter for the charges, I would not need to put the charge into the Aerotech motor build (except maybe the delay to plug the hole between the motor and the airframe?). Do I need to plug that Aerotech motor build with something else?
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Old 06-13-2013, 07:28 PM
Rex R Rex R is offline
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well, if I'm reading this right...your setup is nose cone, forward chute bay(with drogue), av bay, rear chute bay(main), motor and fins...right?
use the delay element to 'plug' the motor case or get a plugged forward closure(think aerotech still wants you to use the delay grain).
rex
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Old 06-13-2013, 07:36 PM
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chadrog chadrog is offline
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Your setup is backwards from traditional. typically your drogue is in the lower section with the main under your cone - this makes it possible to use your motor as backup deployment. Your arrangement makes that impossible. Still curious what size pins your using and how you plan to cut them - cardboard alone will not.
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Old 06-13-2013, 09:09 PM
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Kevin Huddleston Kevin Huddleston is offline
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Yes, it's backwards. Realized it too late. That said, I'm sure it's still workable (and have the altimeter wired accordingly). I was thinking that the delay should just be used as usual without the charge, of course. Just wanted to check. Thanks, guys!
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Old 06-13-2013, 09:11 PM
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Kevin Huddleston Kevin Huddleston is offline
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Chad, I have thin brass plates inside the housing and nosecone to help with the cut. I had read that using CA would be enough, but I added the brass plates for good measure.
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Old 06-13-2013, 11:41 PM
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Sounds like you're good to go, when are you planning to fly it?
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  #9  
Old 06-14-2013, 09:14 AM
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Kevin Huddleston Kevin Huddleston is offline
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Soon, I hope! Been rainy or too windy here for me to launch her. The field I use is compliant with HP guidelines, but just so. Can't have a day with 15 MPH winds and fly too high!

One of my original questions was about black powder. I have 1.5 grams for each charge (maybe .2 grams more than suggested for the volume). There are three shear pins for the main, two for the nose cone. Should I add any more black powder to ensure they will be cut?
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Old 06-14-2013, 01:08 PM
MadHatter MadHatter is offline
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Quote:
Originally Posted by Kevin Huddleston
The field I use is compliant with HP guidelines,


Do you have a FAA waiver for that location? The FAA requires a waiver if:

1). The fully assembled and loaded rocket weighs more than 3.3 lbs (1500 grams)

or...

2). The total propellent weight weighs more than 4.4 oz (125 grams) .

So if you exceed either of these values you must have a waiver, If you need one I can help you with the application process.

Mark
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Last edited by MadHatter : 06-14-2013 at 04:17 PM.
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