Building Launch Controllers

[lcorinth]

I'm interested in building my own launch pads and launch controllers. I'll soon be building a rocket that takes an E motor, and it seems that with each larger motor size (if you just go the Estes route and buy all your ground support stuff), you need to get a new launch pad and a new controller. I've looked at a few homemade controllers online, so I know you can build your own. I'm wondering if it's possible to make a controller, and also a pad, that accommodates multiple sized motors and rockets.

Mind, I'm still talking about LPR, so I'm not at a stage yet where I need to worry about rails or anything.

I've done some Googling, and have found various plans for controllers (and pads), and I could just build one of those. But I'm not entirely sure about the basics - how they function, why they need to be wired the way they do, etc.

I'd like to build a controller that will still work for a standard A-C engine, but will also function for larger ones, like D-E sized motors. I'd also like the same controller to work for cluster engines, so I can use the same controller for my first (simple, 2-motor kit) cluster launch rocket. I'm not sure if these wishes are all possible in one controller (I can still use my Estes controller for the standards, of course). I've never worked with electronics before, but I want to learn how this works. Here's what I think I know:

• You need enough voltage to get the igniter to fire (though I don't know how much voltage that is)
• You need enough amperes to push enough current through the length of wire to the igniter (so, if you have 30 feet of wire instead of 15, you need more amps to get it there). I think this is accomplished through a series of batteries, or a stronger battery perhaps (?)
• You need a weak enough current to run through the igniter to power the continuity light on the controller, but not so much you accidentally launch the rocket
• For cluster launches, you need to wire all igniters in parallel, not in series, with the use of a "clip whip."

I'd like the controller to work on internal power if possible. I know some controllers use series of AA or C batteries. The Estes controller I got with my first kit uses one 9V. I was thinking of one of those lantern batteries with the spring attachments on top, but I think those are 6V, and I don't know if that's enough voltage. I would be willing to use one of those external, rechargeable (motorcycle?) batteries, but I don't want to have to rig the thing to my car. Where I fly, parking is a minimum of 600 feet from the launch site.

I've looked at switches and stuff at Radioshack. What I'm picturing is a small (possibly wooden) box with a battery preferably inside, with a toggle switch to arm, an LED to indicate continuity, and a momentary button switch to launch (with of course the wires - about 30-45 feet - coming out the front). I'm also not sure how to mount these things onto the casing, so I don't know if I can use a wooden box, or if I need something thinner. I don't know if I need some kind of circuit board, or if I can keep it simpler. I don't know if a launcher for a higher power motor will be too much for a standard A-C motor. If that's the case, and I want to get fancy, perhaps I can put in a switch and have two different batteries in the thing, one for higher power stuff, one for the standards. I also don't know how to wire a continuity indicator so it doesn't send all the juice to the launch pad when I simply arm the launch controller - I assume it's some sort of resistor, but I don't know how much resistance I need for what kind of battery.

I'd hasten to add that I'm not in a hurry to do this project, so please don't worry that I'm getting ahead of myself here. But I'd like to begin understanding how I can design this thing - I'd like to design it myself rather than simply copy someone else's, so that I actually understand what I'm making, and can design another one for another use if I need to or want to.

So, what are the basics I need to know about doing something like this? Feel free to be as detailed as possible, but bear in mind that I'm an electronics beginner.

(I was also going to make this thread about launch pads, but this is getting pretty long, so I'll save that for another post).

 

[TopRamen]

You came to the right place! Some of the Folks here make the most incredible Launch Controllers.
I have'nt done it myself either, but want to, so I'll be following this Thread!
Hoping someone posts some Schematics and Parts Lists.

 

[Sooner Boomer]

Here's mine I made from Radio Shack parts:



and the schematic (poorly drawn in Paint):


It's a 12v system that will work off of a car battery or other source. Works great on Estes stuff as well as composite igniters.
Not shown in schematic are battery clips or igniter clips.

Let me go through the RS web site and I'll see if I can get part numbers...

 

[shreadvector]

Just by this and it will work for everything. Read the instructions and use either the 6 internal C alkaline batteries or you can use an internal LiPo pack for larger clusters of motors that use igniters that require more amps.

I'm interested in building my own launch pads and launch controllers. I'll soon be building a rocket that takes an E motor, and it seems that with each larger motor size (if you just go the Estes route and buy all your ground support stuff), you need to get a new launch pad and a new controller. I've looked at a few homemade controllers online, so I know you can build your own. I'm wondering if it's possible to make a controller, and also a pad, that accommodates multiple sized motors and rockets.

Mind, I'm still talking about LPR, so I'm not at a stage yet where I need to worry about rails or anything.

I've done some Googling, and have found various plans for controllers (and pads), and I could just build one of those. But I'm not entirely sure about the basics - how they function, why they need to be wired the way they do, etc.

I'd like to build a controller that will still work for a standard A-C engine, but will also function for larger ones, like D-E sized motors. I'd also like the same controller to work for cluster engines, so I can use the same controller for my first (simple, 2-motor kit) cluster launch rocket. I'm not sure if these wishes are all possible in one controller (I can still use my Estes controller for the standards, of course). I've never worked with electronics before, but I want to learn how this works. Here's what I think I know:

• You need enough voltage to get the igniter to fire (though I don't know how much voltage that is)
• You need enough amperes to push enough current through the length of wire to the igniter (so, if you have 30 feet of wire instead of 15, you need more amps to get it there). I think this is accomplished through a series of batteries, or a stronger battery perhaps (?)
• You need a weak enough current to run through the igniter to power the continuity light on the controller, but not so much you accidentally launch the rocket
• For cluster launches, you need to wire all igniters in parallel, not in series, with the use of a "clip whip."

I'd like the controller to work on internal power if possible. I know some controllers use series of AA or C batteries. The Estes controller I got with my first kit uses one 9V. I was thinking of one of those lantern batteries with the spring attachments on top, but I think those are 6V, and I don't know if that's enough voltage. I would be willing to use one of those external, rechargeable (motorcycle?) batteries, but I don't want to have to rig the thing to my car. Where I fly, parking is a minimum of 600 feet from the launch site.

I've looked at switches and stuff at Radioshack. What I'm picturing is a small (possibly wooden) box with a battery preferably inside, with a toggle switch to arm, an LED to indicate continuity, and a momentary button switch to launch (with of course the wires - about 30-45 feet - coming out the front). I'm also not sure how to mount these things onto the casing, so I don't know if I can use a wooden box, or if I need something thinner. I don't know if I need some kind of circuit board, or if I can keep it simpler. I don't know if a launcher for a higher power motor will be too much for a standard A-C motor. If that's the case, and I want to get fancy, perhaps I can put in a switch and have two different batteries in the thing, one for higher power stuff, one for the standards. I also don't know how to wire a continuity indicator so it doesn't send all the juice to the launch pad when I simply arm the launch controller - I assume it's some sort of resistor, but I don't know how much resistance I need for what kind of battery.

I'd hasten to add that I'm not in a hurry to do this project, so please don't worry that I'm getting ahead of myself here. But I'd like to begin understanding how I can design this thing - I'd like to design it myself rather than simply copy someone else's, so that I actually understand what I'm making, and can design another one for another use if I need to or want to.

So, what are the basics I need to know about doing something like this? Feel free to be as detailed as possible, but bear in mind that I'm an electronics beginner.

(I was also going to make this thread about launch pads, but this is getting pretty long, so I'll save that for another post).

 

[Sooner Boomer]

OK, here's what I came up with...

Heavy-Duty 30-Amp Car Battery Clips
Catalog #: 270-343

or

10-Amp Car Battery Clips
Catalog #: 270-344

Red Button SPST Pushbutton Switch
Catalog #: 275-646

or

3-Amp Soft-Touch Momentary Switch
Catalog #: 275-1566

Toggle Switch with On/Off Label Plate
Catalog #: 275-602

Green LED with Holder
Catalog #: 276-271

60-Ft. 18-Gauge Clear 2-Conductor Speaker Wire
Catalog #: 278-008

Project Enclosure (4x2x1")
Catalog #: 270-1802

I couldn't find the alligator clips for the igniters. From the 60' roll of speaker wire, I use 20' to go from the battery to the box, then 40' to go from the box to the pad. You can make either/both of these longer. Start by drilling holes in the plastic box (top) for the switches and LED, and on the ends for the speaker wires. Cut the speaker wires to length and run about 6" inside the box from each wire. Split the wires inside the box into individual wires and tie an Underwriter's Knot ( https://hope.edu/academic/engineering/labs/Electricity_Lab/Images/LampFig2.jpg ) in each wire. If you look closely, the speaker wire has a smooth wire and a wire with ribs. This helps to keep track of the wires even though they're the same color. Let's use the ribbed wire for the negative wire and the smooth wire for the positive wire. Strip about 1/2" of insulation from each ribbed wire. Twist them together, solder, and tape the joint when cool. Mount the switches and LED in the front paned in the holes you drilled. The shorter of the two pieces of speaker wires goes to the battery. Strip about 1/4" of insulation from the end of this wire and solder it onto one side of the toggle switch. Cut about 3" off of the longer of the two speaker wires (the end not in the box!) and split the two wires apart. Strip about 1/4" off of each end of the smooth wire, and solder one end to the "free" side of the toggle switch. Solder the other end to one side of the pushbutton switch. Strip about 1/4" of insulation from the end of the long piece of speaker wire and solder it to the "free" side of the pushbutton switch. Solder the wires to the LED across the pushbutton switch, positive (red) lead going to the same side of the pushbutton as the toggle switch and negative lead going to the side wired to the long speaker wire. Solder battery clips to the short pair of wires (black or negative to the ribbed wire, red or positive to smooth), and solder alligator clips to the long set of wires. Assemble case and it's ready to go. Polarity is important because you're using an LED instead of a light bulb so watch how you connect to battery.

 

[Tanarin]

@sooner.boomer: Doesn't the controller need a removable key of some sort in order to be up to NAR code? I noticed your controller lacks one unless I am missing something I can't see.

 

[Sooner Boomer]

@sooner.boomer: Doesn't the controller need a removable key of some sort in order to be up to NAR code? I noticed your controller lacks one unless I am missing something I can't see.

You're right, it does. This can be easily added by soldering an audio-type socket on the negative wire, instead of soldering the two wires together. Socket can be an RCA type or a mono 1/8" type. A corresponding plug with the leads shorted will serve as the interlock. Something like...

 

[USAFmissileer]

Aerotech controller I just got with a gel starter battery has been a welcome upgrade to my Estes electron beam. Does all I need. LPR and MPR


Launching rockets (or missiles in my case) is so easy a chimp could do it. Read a step, do a step, eat a banana.

Sent from my iPad Air using Rocketry Forum.

 

[Sooner Boomer]

Launching rockets (or missiles in my case) is so easy a chimp could do it. Read a step, do a step, eat a banana.

Sent from my iPad Air using Rocketry Forum.

There are a lot of ways to make prepping and launching a rocket easy*. It all comes down to design elements: baffles to make loading the chute easier; screw on engine retainers makes loading/removing engines easier; even reloadable motors are "chimp-easy" now.

*ya still gotta chase the dang thing down after launch, though...

 

[race 58]

Can't get any better than this especially for the price. https://www.pratt-hobbies.com/proddetail.asp?prod=GO-12
I have had one for quite awhile and it has never failed me. Added benefit is you will have more time to build rockets rather than a controller.:wink:
I also have their Pad Relay Module or PRM https://www.pratt-hobbies.com/proddetail.asp?prod=PRM-12 to add an extra 12v boost for clusters,Etc.

Hope this helps
Ed

 

[JeromeK99]

Here is a link to an Estes publication on understanding launch controllers. It will only take you a few minutes to read and you will gain a good handle on how a basic launch controller works.

https://www2.estesrockets.com/pdf/2811_Estes_Model_Rocket_Launch_Systems.pdf


Jerome

 

[adrienwapkaplet]

I made a controller quite similar to sooner.boomers diagram... only modification was to put TWO switches in series, so each of my 'launch crew' had a button to push.

 

[USAFmissileer]

There are a lot of ways to make prepping and launching a rocket easy*. It all comes down to design elements: baffles to make loading the chute easier; screw on engine retainers makes loading/removing engines easier; even reloadable motors are "chimp-easy" now.

*ya still gotta chase the dang thing down after launch, though...

Agreed! Things are way easier than in the 70's when I started on the hobby. Also, I should explain that my "tag line" is from my days on nuclear alert as a Minuteman missile crew commander. Everything was, and still is, checklist based, so the running joke was "read a step, do a step, eat a banana." The other one was we were called mushrooms since we were kept in the dark (90 feet down) and fed crap (or insert a colorful expletive here)

With the ease and advancements comes the chance to do things in rocketry that we only dreamed of decades ago. To the original question, I enjoy my Aerotech Interlock controller and am glad I bought it.


Launching rockets (or missiles in my case) is so easy a chimp could do it. Read a step, do a step, eat a banana.

Sent from my iPad Air using Rocketry Forum.

 

[Area66]

and the schematic (poorly drawn in Paint):

View attachment 183303


..

No one notice it ........ this a very dangerous design, no resistor in series with the LED ? As soon as your toggle the switch the rocket will launch.

this is a sase schematic, all true it should be indicated ± 230 ohms resistor



The RS 276-271 you show in your list has already a resistor, but it's not a LED , it's a LED , Resistor, Holder assembly. The schematic don't reflect the part you use. So if you want to make the schematic safe, remove the word LED and put the RS part number and call it LED and Resistor assembly

 

[Sooner Boomer]

No one notice it ........ this a very dangerous design, no resistor in series with the LED ? As soon as your toggle the switch the rocket will launch.

this is a sase schematic, all true it should be indicated ± 230 ohms resistor

View attachment 183435

The RS 276-271 you show in your list has already a resistor, but it's not a LED , it's a LED , Resistor, Holder assembly. The schematic don't reflect the part you use. So if you want to make the schematic safe, remove the word LED and put the RS part number and call it LED and Resistor assembly

Nope, you're wrong. Period. I've used this controller for more than 15 years. I guess you missed the picture of it I posted. LED has current limiting resistor built into it appropriate for use with 12 volts. And you should check your math; your value for the current limiting resistor is about half what it should be. Regarding what it's called - take that up with Radio Shack - I cut-and-pasted all of the part numbers and descriptions directly from their web page. Look for yourself:
https://www.radioshack.com/product/index.jsp?productId=2062569

 

[lcorinth]

Here is a link to an Estes publication on understanding launch controllers. It will only take you a few minutes to read and you will gain a good handle on how a basic launch controller works.

https://www2.estesrockets.com/pdf/2811_Estes_Model_Rocket_Launch_Systems.pdf

Jerome

Thank you for that! I'm putting it on my Kindle right now.

 

[lcorinth]

Can't get any better than this especially for the price. https://www.pratt-hobbies.com/proddetail.asp?prod=GO-12
I have had one for quite awhile and it has never failed me. Added benefit is you will have more time to build rockets rather than a controller.:wink:
I also have their Pad Relay Module or PRM https://www.pratt-hobbies.com/proddetail.asp?prod=PRM-12 to add an extra 12v boost for clusters,Etc.

Hope this helps
Ed

These are going on my wish list.

 

[lcorinth]

Here's mine I made from Radio Shack parts:

View attachment 183302

and the schematic (poorly drawn in Paint):

View attachment 183303
It's a 12v system that will work off of a car battery or other source. Works great on Estes stuff as well as composite igniters.
Not shown in schematic are battery clips or igniter clips.

Let me go through the RS web site and I'll see if I can get part numbers...

Thanks!

 

[Sooner Boomer]

When you get ready to take it to the next level, I've got plans for a multi-pad controller. Great for clubs and clusters, even clusters of composite motors because the battery is located at the pad. This allows the maximum amount of power to go to the igniter (it's switched by relays at the pad), regardless of how far the main controller is from the pad.

 

[Area66]

Nope, you're wrong. Period.

No I'm right , the schematic you show as no resistor, it's show a LED only. Whatever you say in the text is irrelevant, someone may not read it and go only with the schematic.

I guess you missed the picture of it I posted. LED has current limiting resistor built into it appropriate for use with 12 volts.

Did you know how to read ? ... I clearly say your RS Parts as build in resistor. The problem is that you show a led without a resistor in the schematic. Usually a LED come without resistor.

The RS 276-271 you show in your list has already a resistor, but it's not a LED , it's a LED , Resistor, Holder assembly. The schematic don't reflect the part you use. So if you want to make the schematic safe, remove the word LED and put the RS part number and call it LED and Resistor assembly

 

[Area66]

I revise the schematic I find on Google and do 2 versions, a 6V for low power Estes BP motor and a 12V for Aerotech and CTI ignitor.

 

[Micromeister]

I revise the schematic I find on Google and do 2 versions, a 6V for low power Estes BP motor and a 12V for Aerotech and CTI ignitor.

Area66's simple hand held controller circuits really fit the bill for single motor launching.

However if you are planning on flying Clustered BP motors You absolutely need a 12v system and battery that will deliver at least 2amps pre igniter unless Quest's Q2g2 low current igniters come back??? If using standard Solar or worse the new white tipped Estes igniters your really must use a RELAY ignition system.
Below is a schematic and photos of a fairly inexpensive "RangeBox Relay" invented and have been using for about 3.5 decades now This system moves the igniter power supply to the LAUNCHER SIDE of the circuit with it's own 12V battery to the igniters. It is possible to alter this circuit to use a single 12volt high amp power supply with a controller circuit used to activate the relay coil only with igniter continuity built into the relay circuit Not on the controller side.

Another point that must be illuminated is; "Clip Whips" no matter how well made are only an extension of whatever Launch control system they are attached to. They in themselves are NOT the answer to reliable Cluster motor ignition.

When you decide to get into clustered motor models Please visit www.narhams.org library section under Tech-Tip-006 "Clustering BP Motors". This free downloadable article will answer many of the questions and give a number of ways to reliably fly 2-12 BP motor clustered models.

 

[race 58]

When you get ready to take it to the next level, I've got plans for a multi-pad controller. Great for clubs and clusters, even clusters of composite motors because the battery is located at the pad. This allows the maximum amount of power to go to the igniter (it's switched by relays at the pad), regardless of how far the main controller is from the pad.

Again I would go with Doug Pratt for the multi controller or others like it unless you have soldering and electronics know-how to do it yourself.

https://www.pratt-hobbies.com/proddetail.asp?prod=SIXPK-1

Of course if you just want to stay basic then the GoBox is great.

 

[JJSR]

When you get ready to take it to the next level, I've got plans for a multi-pad controller. Great for clubs and clusters, even clusters of composite motors because the battery is located at the pad. This allows the maximum amount of power to go to the igniter (it's switched by relays at the pad), regardless of how far the main controller is from the pad.

sooner.boomer I'd be interested in a multi pad controller, our clubs controller is getting old and only does 5 rockets at a time. We are looking to up that, could yours be tricked out to launch 10 rockets?

 

[Sooner Boomer]

sooner.boomer I'd be interested in a multi pad controller, our clubs controller is getting old and only does 5 rockets at a time. We are looking to up that, could yours be tricked out to launch 10 rockets?

Yes. It could be built to launch as many as you want. Let me dig up the schematics for you.

 

[RocketT.Coyote]

My personal launch controllers are built with Radio Shack parts and key switches obtained through American Science & Surplus. Picked up a spool of white lamp cord way back when the local Builder's Square closed. I use the 12v 7.5 Amp Hr sealed gel batteries--available through farm supply and outdoorsman stores (also Tower Hobby) as a power supply. One controller features an LED with dropping resistor so I must be mindful of polarity. One must view the LED directly to determine continuity. Your results may vary.

I'm planning yet another controller using a lighted covered toggle switch and a large heavy-duty push-button switch obtained at Harbor Freight Tools to be mounted in an aluminum project box.

 

[JJSR]

Yes. It could be built to launch as many as you want. Let me dig up the schematics for you.

That would be great!!

THANKS boomer

 

[Winston]

Nope, you're wrong. Period. I've used this controller for more than 15 years. I guess you missed the picture of it I posted. LED has current limiting resistor built into it appropriate for use with 12 volts. And you should check your math; your value for the current limiting resistor is about half what it should be. Regarding what it's called - take that up with Radio Shack - I cut-and-pasted all of the part numbers and descriptions directly from their web page. Look for yourself:
https://www.radioshack.com/product/index.jsp?productId=2062569

The fact that he missed the need for a specific LED with a built-in current limiting resistor means that others would likely do so, too. When a specific part is needed, especially in a circuit dealing with pyrotechnics, you need to put something other that just "LED" in your schematic and specifically warn that either the exact part must be used or a series resistor of an appropriate value for 12V must be used. An LED without a current limiting resistor would fail open very quickly at 12V, but before it did, it might pass enough current for long enough to fire the igniter, especially if it was a low current type like a Q2G2.

 

[race 58]

My personal launch controllers are built with Radio Shack parts and key switches obtained through American Science & Surplus. Picked up a spool of white lamp cord way back when the local Builder's Square closed. I use the 12v 7.5 Amp Hr sealed gel batteries--available through farm supply and outdoorsman stores (also Tower Hobby) as a power supply. One controller features an LED with dropping resistor so I must be mindful of polarity. One must view the LED directly to determine continuity. Your results may vary.

I'm planning yet another controller using a lighted covered toggle switch and a large heavy-duty push-button switch obtained at Harbor Freight Tools to be mounted in an aluminum project box.

Happen to have the parts list you used or are going to use... Inquiring minds want to know.


Ed

 

[lcorinth]

Area66's simple hand held controller circuits really fit the bill for single motor launching.

However if you are planning on flying Clustered BP motors You absolutely need a 12v system and battery that will deliver at least 2amps pre igniter unless Quest's Q2g2 low current igniters come back??? If using standard Solar or worse the new white tipped Estes igniters your really must use a RELAY ignition system.
Below is a schematic and photos of a fairly inexpensive "RangeBox Relay" invented and have been using for about 3.5 decades now This system moves the igniter power supply to the LAUNCHER SIDE of the circuit with it's own 12V battery to the igniters. It is possible to alter this circuit to use a single 12volt high amp power supply with a controller circuit used to activate the relay coil only with igniter continuity built into the relay circuit Not on the controller side.

Another point that must be illuminated is; "Clip Whips" no matter how well made are only an extension of whatever Launch control system they are attached to. They in themselves are NOT the answer to reliable Cluster motor ignition.

When you decide to get into clustered motor models Please visit www.narhams.org library section under Tech-Tip-006 "Clustering BP Motors". This free downloadable article will answer many of the questions and give a number of ways to reliably fly 2-12 BP motor clustered models.

Thanks for the link. I'm going to check that out.

The basic (standard engine, 1-engine) launch controller looks pretty simple. I might build a simple one for single-engine launches (there's a really easy one on the NAR website) just to get the hang of it, and better understand how these things work.