Launch controller

[user 35280]

Do you connect that to the PSII through the JST connector? And what amp hours is your battery?

I don’t use a Estes PSII controller, I use the Go Box from Pratt Hobbies.

 

[brockrwood]

If I was going to bother making a controller, it would be lipo powered. And my lipos would laugh at 100amps load. They'll roast your leads long before getting anywhere close to internal thermal overload.

So I'd run a much larger fuse, and/or a relay.

If using a high current battery, like a LiPo, I think the relay type controller is the way to go.

 

[Dane Ronnow]

Just wondering if a 5Ah SLA battery would be sufficient for Aerotech G motor ignition. It would be connected to the PSII controller through a JST connector.

 

[brockrwood]

If I was going to bother making a controller, it would be lipo powered. And my lipos would laugh at 100amps load. They'll roast your leads long before getting anywhere close to internal thermal overload.

So I'd run a much larger fuse, and/or a relay.

Gosh. How much current is needed for composite motors? I have only launched black powder motor, low power rockets. A rule of thumb for a cluster of black powder motors is 2 amps per motor. Even with 4 motors in a cluster that is only a total of 8 amps needed to launch the rocket.

 

[user 35280]

Just wondering if a 5Ah SLA battery would be sufficient for Aerotech G motor ignition. It would be connected to the PSII controller through a JST connector.

Don’t know, but that’s what I have/use. The biggest motor I’ve ignited so far is a AT SU F67. I did get the power pad relay so I can hook up a 12V car battery for the bigger motors.

 

[Scott_650]

Gosh. How much current is needed for composite motors? I have only launched black powder motor, low power rockets. A rule of thumb for a cluster of black powder motors is 2 amps per motor. Even with 4 motors in a cluster that is only a total of 8 amps needed to launch the rocket.

I’ve used my Estes #2240 PSII Launch Controller with NiMH rechargeable C cells or alkaline C cells to launch Aerotech 29mm DMS G motors with no problems - so whatever amount of juice those produce works just fine

 

[tokind]

Actually, a 5 amp fuse might be too low of a value. A LiPo or SLA battery can supply more than 5 amps (for a short period of time). Play with the value of the fuse until it does not blow too quickly. Maybe start with a 10 amp fuse and play with the value. The idea of the fuse is just to protect from a true short circuit. You do not want the fuse to blow when the circuit simply provides the high current, for a short period of time, needed to ignite the rocket motor.

A "slo-blo" fuse might be the solution.

We use a 10a Thermal breaker. It has done the job in the field and in test.

 

[tokind]

I attached a PDF with Schematics, Theory of Operation, and Bill of Materials for a single channel HPR Controller. The BOM does not include battery connectors (EC5 connectors) or the ethernet jacks for you to use cheap ethernet cables for the extension. Your extension needs a four conductor cable. Parts you might exclude to reduce cost are the Arm Siren and the red paddles over the Arm/Safe switches.

I posted a thread to Ground Support about how to use an Automotive Jump-Start (LiPo) battery as a field power source.

 

[brockrwood]

We use a 10a Thermal breaker. It has done the job in the field and in test.

Thanks for the cool idea!

 

[brockrwood]

Don’t know, but that’s what I have/use. The biggest motor I’ve ignited so far is a AT SU F67. I did get the power pad relay so I can hook up a 12V car battery for the bigger motors.

I made a homemade “relay” type launch controller a few years ago. I have only used it a few times. I use it to launch clusters (2 or 3) 18mm black powder motors. It works well. The reason I wanted the relay type controller is so I could stand back, farther away from the launch pad. If the ignition battery has to be connected by a really long set of wires to the launch pad, then you need heavy gauge wire and that is heavy and bulky. The relay controller has a mere 6 feet of heavy gauge wire (lamp cord) between the powerful battery, its relay, and the launch pad. The relay is hooked up to another, lower current battery, by light gauge wire. I can stand about 40 feet away, as the 40 feet of light gauge wire connects the small battery and my “launch button” to the relay. I don’t have to lug 40 feet of heavy gauge wire with me. When I press the launch button, it just energizes the relay (from the small battery) and the relay connects the high current battery to the igniters on the cluster rocket.

 

[tokind]

Gosh. How much current is needed for composite motors? I have only launched black powder motor, low power rockets. A rule of thumb for a cluster of black powder motors is 2 amps per motor. Even with 4 motors in a cluster that is only a total of 8 amps needed to launch the rocket.

HPR ignitors don't really require that much more current to ignite. I agree with statements here about Lipo Batteries. I am attaching a research report by JA Brohm from 2019. It contains a lot of very useful information about simple controllers, and is informative to this discussion.

 

[user 35280]

I made a homemade “relay” type launch controller a few years ago. I have only used it a few times. I use it to launch clusters (2 or 3) 18mm black powder motors. It works well. The reason I wanted the relay type controller is so I could stand back, farther away from the launch pad. If the ignition battery has to be connected by a really long set of wires to the launch pad, then you need heavy gauge wire and that is heavy and bulky. The relay controller has a mere 6 feet of heavy gauge wire (lamp cord) between the powerful battery, it’s relay, and the launch pad. The relay is hooked up to another, lower current battery, by light gauge wire. I can stand about 40 feet away, as the 40 feet of light gauge wire connects the small battery and my “launch button” to the relay. I don’t have to lug 40 feet of heavy gauge wire with me. When I press the launch button, it just energizes the relay (from the small battery) and the relay connects the high current battery to the igniters on the cluster rocket.

I just twist the igniter wires together for clusters on low power launches and use my go box with my little 12v SLA battery. Even single motor mid power launches work great with it. I got the power pad relay for down the road if I decide I want to attempt a launch to get a L1.

 

[brockrwood]

I just twist the igniter wires together for clusters on low power launches and use my go box with my little 12v SLA battery. Even single motor mid power launches work great with it. I got the power pad relay for down the road if I decide I want to attempt a launch to get a L1.

Go Box has 30 feet of fairly heavy wire, right? I will admit that my 12 volt power source is just two 6 volt, alkaline “lantern” batteries wired in series. They are not very popular batteries these days but I had them sitting around so I figured I would use them. I use a relay type homemade controller to connect them to the igniters. They launch a three engine cluster of Estes black powder A8-3’s just fine. When they die I will get an SLA battery. Is there a particular SLA battery you recommend?

 

[user 35280]

Go Box has 30 feet of fairly heavy wire, right? I will admit that my 12 volt power source is just two 6 volt, alkaline “lantern” batteries wired in series. They are not very popular batteries these days but I had them sitting around so I figured I would use them. I use a relay type homemade controller to connect them to the igniters. They launch a three engine cluster of Estes black powder A8-3’s just fine. When they die I will get an SLA battery. Is there a particular SLA battery you recommend?

I’m not sure the gauge of the wire, it looks like small speaker wire. The go box came with a 25 foot cable and I bought an extra 25 foot cable, because I wanted to be further away from the pad for safety. I’d think your two 6v lantern batteries would work just fine. Back as a kid in the mid 70’s to mid 80’s I used one 6v lantern battery with my Estes astron launch controller, worked great. Biggest motors I used back then was the mighty D.
I bought the following battery,
https://www.rocketryworks.com/12-volt-5ah-sla-agm-battery/And they sell a nice battery charger too.
But I think you could get a nice small 12v SLA rechargeable battery at your local battery plus/interstate battery store, etc.

 

[brockrwood]

I’m not sure the gauge of the wire, it looks like small speaker wire. The go box came with a 25 foot cable and I bought an extra 25 foot cable, because I wanted to be further away from the pad for safety. I’d think your two 6v lantern batteries would work just fine. Back as a kid in the mid 70’s to mid 80’s I used one 6v lantern battery with my Estes astron launch controller, worked great. Biggest motors I used back then was the mighty D.
I bought the following battery,
https://www.rocketryworks.com/12-volt-5ah-sla-agm-battery/And they sell a nice battery charger too.
But I think you could get a nice small 12v SLA rechargeable battery at your local battery plus/interstate battery store, etc.

Great info. Thanks!

 

[user 35280]

Go Box has 30 feet of fairly heavy wire, right? I will admit that my 12 volt power source is just two 6 volt, alkaline “lantern” batteries wired in series. They are not very popular batteries these days but I had them sitting around so I figured I would use them. I use a relay type homemade controller to connect them to the igniters. They launch a three engine cluster of Estes black powder A8-3’s just fine. When they die I will get an SLA battery. Is there a particular SLA battery you recommend?

One other thing, if you decide you want to eventually try and get into HPR I believe the minimum distance you have to be away from the launch pad is 100 feet. The distance increases as you get into higher power motors. For that you’re going to have to join and/or launch with a NAR and/or Tripoli club as they’re going to have the equipment and the people to help/mentor you and help you get the certification(s).

 

[brockrwood]

One other thing, if you decide you want to eventually try and get into HPR I believe the minimum distance you have to be away from the launch pad is 100 feet. The distance increases as you get into higher power motors. For that you’re going to have to join and/or launch with a NAR and/or Tripoli club as they’re going to have the equipment and the people to help/mentor you and help you get the certification(s).

I haven’t really seem myself getting into HPR, or even MPR. The cost and time barriers are big. Also, I enjoy the hobby from a math and science standpoint, which can all be done with inexpensive, LPR rockets. I am also enjoying the modeling aspect of the hobby, which works fine with LPR rockets.

I enjoy clustering and staging, which, again, work fine with LPR rockets.

When I say I am a BAR, I mean it literally. I am a kid again, in a grown up’s body, enjoying building and flying the Estes-type rockets that I loved as a kid.

I enjoy helping young people get into the hobby and teaching them math and science along the way. Again, that works fine with LPR.

I enjoy kit bashing - easy to do with LPR.


I still haven’t mastered LPR. I need to bulld my Estes Executioner and my Double D Squared. Once I do that, I will assess whether I want to try MPR. I am having a lot of fun just being a kid again!

 

[neil_w]

There is no requirement, legal or otherwise, that you must progress to MPR and then HPR. Do what you enjoy.

 

[brockrwood]

There is no requirement, legal or otherwise, that you must progress to MPR and then HPR. Do what you enjoy.

Oh, for sure!
I have no problems with folks who are into MPR and HPR. I think that is great! Go for it! I am just still not done with LPR. Having a great time being a kid again!

 

[user 35280]

I haven’t really seem myself getting into HPR, or even MPR. The cost and time barriers are big. Also, I enjoy the hobby from a math and science standpoint, which can all be done with inexpensive, LPR rockets. I am also enjoying the modeling aspect of the hobby, which works fine with LPR rockets.

I enjoy clustering and staging, which, again, work fine with LPR rockets.

When I say I am a BAR, I mean it literally. I am a kid again, in a grown up’s body, enjoying building and flying the Estes-type rockets that I loved as a kid.

I enjoy helping young people get into the hobby and teaching them math and science along the way. Again, that works fine with LPR.

I enjoy kit bashing - easy to do with LPR.


I still haven’t mastered LPR. I need to bulld my Estes Executioner and my Double D Squared. Once I do that, I will assess whether I want to try MPR. I am having a lot of fun just being a kid again!

If your location is indeed Denver there’s three rocket clubs that I know of that’s close, CRASH, COSROCS and SCORE. I believe there’s several more around the State too. Lots of cool rocket launches, low, mid and high power at all those clubs. Go around and enjoy them all, if you can.

 

[brockrwood]

There is no requirement, legal or otherwise, that you must progress to MPR and then HPR. Do what you enjoy.

What exactly is the dividing line between LPR

If your location is indeed Denver there’s three rocket clubs that I know of that’s close, CRASH, COSROCS and SCORE. I believe there’s several more around the State too. Lots of cool rocket launches, low, mid and high power at all those clubs. Go around and enjoy them all, if you can.

Great clubs in Colorado! Hey, no offense intended. Thanks for the info on the HPR distance limits. I just haven’t gotten into MPR or HPR as of yet. I may in the future. I have a lot more to accomplish in LPR before I can consider myself to have mastered LPR. I have no problem with MPR and HPR folks. I think MPR and HPR folks are awesome! As it turns out, my Estes Executioner flies on an E9. That’s technically MPR, yes? Ok, I AM into MPR! ;-)

 

[brockrwood]

What exactly is the dividing line between LPR

Great clubs in Colorado! Hey, no offense intended. Thanks for the info on the HPR distance limits. I just haven’t gotten into MPR or HPR as of yet. I may in the future. I have a lot more to accomplish in LPR before I can consider myself to have mastered LPR. I have no problem with MPR and HPR folks. I think MPR and HPR folks are awesome! As it turns out, my Estes Executioner flies on an E9. That’s technically MPR, yes? Ok, I AM into MPR! ;-)

If your location is indeed Denver there’s three rocket clubs that I know of that’s close, CRASH, COSROCS and SCORE. I believe there’s several more around the State too. Lots of cool rocket launches, low, mid and high power at all those clubs. Go around and enjoy them all, if you can.

What is the dividing line between LPR and MPR?

 

[neil_w]

What is the dividing line between LPR and MPR?

There's no official line.

Generally, D and below are considered LPR, F and G are considered MPR. E could go either way.

 

[user 35280]

What is the dividing line between LPR and MPR?

I think for the BP motors low power currently is 1/8A thru D
BP motors for mid power is E and F
Clustering to many low power and/or mid power motors can put you into high power range.

 

[brockrwood]

I think for the BP motors low power currently is 1/8A thru D
BP motors for mid power is E and F
Clustering to many low power and/or mid power motors can put you into high power range.

I will cluster my black powder E motors to make sure I am fully into the MPR range. Then I can say, with a straight face, "yes, I am into MPR". ;-)

 

[brockrwood]

If your location is indeed Denver there’s three rocket clubs that I know of that’s close, CRASH, COSROCS and SCORE.

Several years ago, I used to launch with the CRASH folks out at the Bear Creek Lake Park in Lakewood, Colorado. They don't launch there anymore. Not sure why. They now have another launch site north and east of Denver. I will have to check it out.

 

[brockrwood]

Just wondering if a 5Ah SLA battery would be sufficient for Aerotech G motor ignition. It would be connected to the PSII controller through a JST connector.

I have never tried to fire an Aerotech G motor, but it seems to me that any battery with enough current to set off the igniter for the engine will get the engine ignited. Per the post by @tokind in this thread, check out the igniter continuity article by J. R. Brohm (2009). Brohm measures the firing current for five different igniters, including the Q2G2 and Copperhead igniters commonly used with composite motors. The Copperhead needs 1.6 amps to fire, so about 2 amps ought to set off the Copperhead very reliably. The Q2G2 takes only about .27 amps to fire, so about 1 amp ought to set it off reliably. If the igniter inserted into your motor is firing reliably, the rocket motor it is inserted into, as long as you have done everything else right, should also ignite reliably. The First Fire Junior igniter required 1.78 amps to set it off.

So, as long as you are igniting only one motor (not a cluster), and as long as you are using the right igniter for the motor, I don't see why the short term current capability of the battery needs to be more than 2 amps. So, a sealed lead acid (SLA) battery with a 2,000 mAh rating ought to be sufficient.

(I am assuming a 12V battery, which should be enough voltage to send a high current pulse through a single igniter.)

NOW, with that said, if you are launching all day, over and over again, rocket after rocket, with no recharge of the battery, and with each launch of a rocket making the battery send at least a 2A current down the wire, you might want a higher amp-hour capacity (say, your 5 Ah battery) for one very good reason: The higher capacity will not go flat as fast and can launch more rockets before needing to be recharged.

Here is a spec sheet for a typical 5Ah SLA battery:

https://batteryguy.com/files/techni...g-1250f1&f2-technical-specification-sheet.pdf
It supposed to be able to sustain a 5 amp output for 30 minutes, ending at a charge of 9.6 volts (flat and needs to be recharged).

That should be plenty of battery capacity for an afternoon of launching from one pad.

 

[Ronz Rocketz]

I know it's based upon the impulse of the motor. To me, it's the altitude. 1000 to 5000 ft is MPR. I say this knowing that at 5000ft, my rockets might land on Midway.

BTW, here's the battery that @BEC uses in his PSII controller. I'm not sure if that's a JST connector or what.

 

[Dane Ronnow]

I'm not sure if that's a JST connector or what.

The connector in an Estes PSII controller is a JST RCY type:
https://www.amazon.com/gp/product/B071XN7C43/

 

[UhClem]

When I do all fire testing I use a 100ms current pulse. (Q2G2 came out as 333mA)

A 2Ah capacity battery is more than enough. Assume that on average the load pulls 10A for 5 seconds. 2Amp-hour * 3600 seconds/hour/50 Amp-seconds = 144 launches.

Capacity is only loosely related to internal resistance. I have a 1 Ohm 25W resistor that is very handy for testing. Connect in place of igniter and measure the voltage across it. A good 12V system should manage 10V or better.

I have a 4.5Ah SLA battery that I use but I am on the lookout for a 4 cell LiFe battery of around 1Ah capacity.