quickburst
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Everything you always wanted to know about clustering but was afraid to ask.
Clustered Ignition 101
It is said that there is More than one way to skin a cat. This is true; there are many approaches to clustering. The following describes my way of doing it. This does not imply that what you do or what you have seen others do is wrong. The process I use has been successful for me, and I wanted to share it. I believe that clustering is more about safety than anything else. Being successful at lighting one or two of three planned motors is not a success nor is it safe. I describe success as being able to ignite all motors as planned each and every time. Now Murphy steps in. There is no such thing as a sure fire igniter. Igniters are mechanical beasts, and will fail from time to time. Design your clustered project to fly stable under the worse case scenario.
A cluster is the art of lighting more than one motor at the same time. Most of the time they are lit on the ground, other times they are lit in the air. Each configuration has its own set of challenges. The purpose of this paper is to address ground started clusters.
All of the descriptions below are using my ignition products available at QuickBurst. I am not familiar with other manufacturers products, so I cant say weather they will produce the same results or not. Please do not write me asking if the First Fires, Magnelite, Home Brew, Cousin Jims Igniters, CopperHeads or Uncle Bills Igniters or whatever will work. The truth is; I have no idea.
Ground testing is the best bet. Always ground test your ignition set up, before you bet your bird and the others safety.
Clustering Black Powder Motors:
Ground Starts.
The Estes type black powder (BP) motors are possibly the easiest to light. Using the right igniter will almost guarantee the desired result. The suggested Igniter here is the Hot Shot. These are great little black powder motor igniters. The example below is written assuming we are flying a three motor cluster. Many more motors can be lit at once using the Hot Shots/Igniters, this is just an example. I have been able to light seven motors at once with out a problem. The upper limit seems to be around 10.
Clustering APCP Motors:
Ground Starts
APCP (Ammonium Perchlorate Composite Propellant) motors are a little harder to light. The Hot Shots are designed for Black Powder motors and will most likely not work on APCP. Here we will be using a hotter igniter. As a matter of fact, we will make the igniters ourselves. If you have the right components its not really a difficult task. The ideas below apply to single use or RMS or re-loadable motor system, Aerotech type motors in the G or below range. Larger motors open them selves up to easier tactics and will not be discussed this time around.
Lets make the igniters first. I will do the best I can to describe the process; some things are difficult to put into text.
Items needed:
Lead wire You will need some 24 to 26 gauge solid core copper wire for the leads. I do not suggest using stranded wire. Cat 5 Non Plenum cable or telephone wire is a good choice and can be had reasonably. I suggest using the Cat 5 Non Plenum and the description below reflects its use.
Nichrome resistance wire Nichrome is the best choice for constructing the heating element or bridge. I suggest using 36 gauge Nichrome, this will serve your purpose well.
Pyrogen QuickDip is all I use . I wonder why? You will also need some acetone. Acetone is available at most hardware or Home Improvement stores.
Making the igniters This is pretty easy. Cut Cat5 cable into 15 lengths. Longer or shorter will not matter but 15 seems to be the best fit. Now strip the outer insulation off. What you have now is four nice pairs of wire each with a dark insulator ad a white or lighter insulation. This color difference will come in handy later. OK, now you have the four 15 long leads. Separate the first two inches or so of one end. Now cut about ½ of one lead off. What you have now is a pair of leads with one end shorter than the other. Now strip about ¼ insulation off each end. Twist them back together leaving the bare short end laying flat against the remaining insulation on the longer lead. Look at your lead. Both ends are bare and laying together, there is about ½" of insulation between the two bare ends. This is important, make sure you have about ½ distance between the two. I hand wrap the bridges and have never used a wrapping tool. If you feel like you need the tool they can be found at Radioshack (or so Im told). Holding the end of the leads in one hand wrap the nichrome around the exposed copper. Six tight wraps should be fine. Start at the bottom and work your way up in a tight spiral, make sure you are in contact with the copper all the way up. When you hit the insulation on the longer lead keep wrapping. Use about four wraps once again spiraling up the insulation. Now do the last wrap around the exposed copper on the longer lead, six wraps are fine, being sure to stay on the copper. Bend the top copper lead over on itself and crimp. Finished! A little practice and you will be an expert. If you desire you can silver solder the joints, but I have never found it necessary.
Alright; were ready to dip. Thin the QuickDip as required. Usually a syrupy consistency will give you the best coating(s). Dip the bridge, remove and blow lightly. Your breath will dry the QuickDip. Re-dip as needed. Keep in mind that your igniter has to fit through the nozzle of the motors you are using and size accordingly. I like to dip about an inch past the bridge. This will give you plenty of pyrogen and a longer burn time. Hang the igniters to dry. I like to hang them upside down.
Inspect and test Check continuity and resistance. You will need a VOM to do this. I suggest you buy a digital VOM, not that they are any better, Im just used to them. Radioshack will have a model in your price range.
Check for continuity- Using the audible continuity check on your VOM touch both leads. You should hear a tone. The tone means you have continuity or a complete circuit. If you have no tone, cut the bad end off and start from scratch.
Check Resistance- Set your VOM to its lowest resistance scale, usually this is about 200 ohms. Touch both leads, you should show about 1.5 to2 Ohms resistance. A little (.5 ohm) above or a little below will not make that much difference.
If both tests pass, congratulations! You did it.
Ground test a few of your igniters, you will find that they light instantly and have a good hot burn. Heat is the key, the more the merrier. Use a 12 volt launch control for the best results.
Back to Clustering:
Follow the same procedure below. Substituting your igniters for the Hot Shots. For the best results use the Cluster Buster. This is the single best piece of advice I can give you.
Once again, Im not claiming this is the only way to do it. It is the way I do it and I have had and seen nothing but great results.
Procedure:
1. Prep Rocket for flight.
2. Install motors
3. Inspect the Hot Shots/Igniters, test each igniter for continuity. If the igniter fails the continuity check, dispose of it. It will not fire.
4. The leads are 12/15 long. Split the leads about two inches up then strip an inch of insulation off.
5. Note that one lead has a red stripe, the other does not. This is a good way to keep things in order and assure that you have matched the pairs up properly.
6. If using igniters match the dark leads and the white leads.
7. Twist the three red striped leads together, firmly.
8. Now twist the remaining three leads together, firmly.
9. Solder them if desired. This is a good idea but not required.
10. This is called parallel hook up.
11. You now have a bundle of three igniters with a lead from each side of the igniters twisted together.
12. Check your project in with the LCO and go to the pad.
13. Insert a Hot Shot/Igniter into each motor. Be sure you have it all the way in. The igniter must be touching the BP/APCP grain. If Hot Shots use the Estes plugs to hold the igniter in place. If Igniters use most anything to hold them in place. Masking tape works in a pinch.
14. Be sure to route the igniter leads so that none of the leads are directly under another motors exhaust plume. This will burn the insulation off and possibly cause a failure.
15. Using a bit of masking tape, bend the leads up the side of the rocket and tape in place.
16. Position your Cluster Buster.
17. Use a twisted pair of 16 gauge lampcord about six feet long to tie into the igniter leads. Coil this on the ground directly under the rocket. Why are we doing this? The reason is simple, in order to have the best chance for ignition of all motors we are going to use this piece of wire to extend the igniter leads and add a little time. This will allow the rocket to pull a length of wire up the rod/rail with it, and give all the motors a little extra time to come up to pressure. A small bit of insurance is a good idea.
18. Attach the launch control clips to the Cluster Buster as normal. Be sure to inspect them, make sure they are clean and you are getting good contact. I can not stress this enough. Many cluster problems start here. You must provide a solid connection.
19. You are ready to fly.
Good Luck.
Clustered Ignition 101
It is said that there is More than one way to skin a cat. This is true; there are many approaches to clustering. The following describes my way of doing it. This does not imply that what you do or what you have seen others do is wrong. The process I use has been successful for me, and I wanted to share it. I believe that clustering is more about safety than anything else. Being successful at lighting one or two of three planned motors is not a success nor is it safe. I describe success as being able to ignite all motors as planned each and every time. Now Murphy steps in. There is no such thing as a sure fire igniter. Igniters are mechanical beasts, and will fail from time to time. Design your clustered project to fly stable under the worse case scenario.
A cluster is the art of lighting more than one motor at the same time. Most of the time they are lit on the ground, other times they are lit in the air. Each configuration has its own set of challenges. The purpose of this paper is to address ground started clusters.
All of the descriptions below are using my ignition products available at QuickBurst. I am not familiar with other manufacturers products, so I cant say weather they will produce the same results or not. Please do not write me asking if the First Fires, Magnelite, Home Brew, Cousin Jims Igniters, CopperHeads or Uncle Bills Igniters or whatever will work. The truth is; I have no idea.
Ground testing is the best bet. Always ground test your ignition set up, before you bet your bird and the others safety.
Clustering Black Powder Motors:
Ground Starts.
The Estes type black powder (BP) motors are possibly the easiest to light. Using the right igniter will almost guarantee the desired result. The suggested Igniter here is the Hot Shot. These are great little black powder motor igniters. The example below is written assuming we are flying a three motor cluster. Many more motors can be lit at once using the Hot Shots/Igniters, this is just an example. I have been able to light seven motors at once with out a problem. The upper limit seems to be around 10.
Clustering APCP Motors:
Ground Starts
APCP (Ammonium Perchlorate Composite Propellant) motors are a little harder to light. The Hot Shots are designed for Black Powder motors and will most likely not work on APCP. Here we will be using a hotter igniter. As a matter of fact, we will make the igniters ourselves. If you have the right components its not really a difficult task. The ideas below apply to single use or RMS or re-loadable motor system, Aerotech type motors in the G or below range. Larger motors open them selves up to easier tactics and will not be discussed this time around.
Lets make the igniters first. I will do the best I can to describe the process; some things are difficult to put into text.
Items needed:
Lead wire You will need some 24 to 26 gauge solid core copper wire for the leads. I do not suggest using stranded wire. Cat 5 Non Plenum cable or telephone wire is a good choice and can be had reasonably. I suggest using the Cat 5 Non Plenum and the description below reflects its use.
Nichrome resistance wire Nichrome is the best choice for constructing the heating element or bridge. I suggest using 36 gauge Nichrome, this will serve your purpose well.
Pyrogen QuickDip is all I use . I wonder why? You will also need some acetone. Acetone is available at most hardware or Home Improvement stores.
Making the igniters This is pretty easy. Cut Cat5 cable into 15 lengths. Longer or shorter will not matter but 15 seems to be the best fit. Now strip the outer insulation off. What you have now is four nice pairs of wire each with a dark insulator ad a white or lighter insulation. This color difference will come in handy later. OK, now you have the four 15 long leads. Separate the first two inches or so of one end. Now cut about ½ of one lead off. What you have now is a pair of leads with one end shorter than the other. Now strip about ¼ insulation off each end. Twist them back together leaving the bare short end laying flat against the remaining insulation on the longer lead. Look at your lead. Both ends are bare and laying together, there is about ½" of insulation between the two bare ends. This is important, make sure you have about ½ distance between the two. I hand wrap the bridges and have never used a wrapping tool. If you feel like you need the tool they can be found at Radioshack (or so Im told). Holding the end of the leads in one hand wrap the nichrome around the exposed copper. Six tight wraps should be fine. Start at the bottom and work your way up in a tight spiral, make sure you are in contact with the copper all the way up. When you hit the insulation on the longer lead keep wrapping. Use about four wraps once again spiraling up the insulation. Now do the last wrap around the exposed copper on the longer lead, six wraps are fine, being sure to stay on the copper. Bend the top copper lead over on itself and crimp. Finished! A little practice and you will be an expert. If you desire you can silver solder the joints, but I have never found it necessary.
Alright; were ready to dip. Thin the QuickDip as required. Usually a syrupy consistency will give you the best coating(s). Dip the bridge, remove and blow lightly. Your breath will dry the QuickDip. Re-dip as needed. Keep in mind that your igniter has to fit through the nozzle of the motors you are using and size accordingly. I like to dip about an inch past the bridge. This will give you plenty of pyrogen and a longer burn time. Hang the igniters to dry. I like to hang them upside down.
Inspect and test Check continuity and resistance. You will need a VOM to do this. I suggest you buy a digital VOM, not that they are any better, Im just used to them. Radioshack will have a model in your price range.
Check for continuity- Using the audible continuity check on your VOM touch both leads. You should hear a tone. The tone means you have continuity or a complete circuit. If you have no tone, cut the bad end off and start from scratch.
Check Resistance- Set your VOM to its lowest resistance scale, usually this is about 200 ohms. Touch both leads, you should show about 1.5 to2 Ohms resistance. A little (.5 ohm) above or a little below will not make that much difference.
If both tests pass, congratulations! You did it.
Ground test a few of your igniters, you will find that they light instantly and have a good hot burn. Heat is the key, the more the merrier. Use a 12 volt launch control for the best results.
Back to Clustering:
Follow the same procedure below. Substituting your igniters for the Hot Shots. For the best results use the Cluster Buster. This is the single best piece of advice I can give you.
Once again, Im not claiming this is the only way to do it. It is the way I do it and I have had and seen nothing but great results.
Procedure:
1. Prep Rocket for flight.
2. Install motors
3. Inspect the Hot Shots/Igniters, test each igniter for continuity. If the igniter fails the continuity check, dispose of it. It will not fire.
4. The leads are 12/15 long. Split the leads about two inches up then strip an inch of insulation off.
5. Note that one lead has a red stripe, the other does not. This is a good way to keep things in order and assure that you have matched the pairs up properly.
6. If using igniters match the dark leads and the white leads.
7. Twist the three red striped leads together, firmly.
8. Now twist the remaining three leads together, firmly.
9. Solder them if desired. This is a good idea but not required.
10. This is called parallel hook up.
11. You now have a bundle of three igniters with a lead from each side of the igniters twisted together.
12. Check your project in with the LCO and go to the pad.
13. Insert a Hot Shot/Igniter into each motor. Be sure you have it all the way in. The igniter must be touching the BP/APCP grain. If Hot Shots use the Estes plugs to hold the igniter in place. If Igniters use most anything to hold them in place. Masking tape works in a pinch.
14. Be sure to route the igniter leads so that none of the leads are directly under another motors exhaust plume. This will burn the insulation off and possibly cause a failure.
15. Using a bit of masking tape, bend the leads up the side of the rocket and tape in place.
16. Position your Cluster Buster.
17. Use a twisted pair of 16 gauge lampcord about six feet long to tie into the igniter leads. Coil this on the ground directly under the rocket. Why are we doing this? The reason is simple, in order to have the best chance for ignition of all motors we are going to use this piece of wire to extend the igniter leads and add a little time. This will allow the rocket to pull a length of wire up the rod/rail with it, and give all the motors a little extra time to come up to pressure. A small bit of insurance is a good idea.
18. Attach the launch control clips to the Cluster Buster as normal. Be sure to inspect them, make sure they are clean and you are getting good contact. I can not stress this enough. Many cluster problems start here. You must provide a solid connection.
19. You are ready to fly.
Good Luck.
I am going to at least make them with your PD.
