External switch for RRC3+ ?

[timster68]

I want to use two switches with my RRC3+ altimeter. One for the power to the altimeter itself and one just to connect/disconnect the circuit for the e-match.

I am thinking of using these to control the power to the altimeter and having it accessible externally next to the hatch door on the 7.5" T-LOC I am finishing.


I like the idea of being able to power on the altimeter and be able to complete the testing of the e-match circuit after the door to the hatch is closed. There are more than a few screws to remove.

Testing will be done before it is deployed. Does anyone have experience with using these switches?

 

[sharkbait]

I want to use two switches with my RRC3+ altimeter. One for the power to the altimeter itself and one just to connect/disconnect the circuit for the e-match.

I am thinking of using these to control the power to the altimeter and having it accessible externally next to the hatch door on the 7.5" T-LOC I am finishing.

View attachment 615387
I like the idea of being able to power on the altimeter and be able to complete the testing of the e-match circuit after the door to the hatch is closed. There are more than a few screws to remove.

Testing will be done before it is deployed. Does anyone have experience with using these switches?

Looks like a nice switch, but if it’s push button and externally mounted you could have a tube, nose cone, or harness bump it on the way down and shut it off, assuming you are doing DD here

 

[Handeman]

Looks like a nice switch, but if it’s push button and externally mounted you could have a tube, nose cone, or harness bump it on the way down and shut it off, assuming you are doing DD here

I agree with this.

I'm also wondering how you plan to wire it up to do testing? I normally connect all matches and then turn on the altimeter to verify continuity and connection to the matches. Then it gets turned off and the powder added. It doesn't get turned on again until it's on the pad.

Will this altimeter allow you to turn on the altimeter and later connect the ematches? Some need to have the matches connected when doing power up or they don't do flight mode correctly.

 

[ep29030]

Look at the pull pin switches at Lab Rat Rocketry for an alternate approach. They arm when you pull out a long pin inside the rocket.

 

[Titan II]

1. Mount the switch(s) on the electronics board and push on and off through a hole with a small screwdriver, allen wrench, etc.

2. What is the purpose of the e-match switches? You are adding unnecessary failure points.

 

[Steve Shannon]

Here’s what I don’t like about push on/push off buttons:
1. I’ve never seen one that was rated for shock and vibration. Microswitches as used in the LabRat rocketry pull pin switches and the slide switches sold by PML (in the past; I don’t know if LOC still sells the same ones) in the NKK catalog are rated for 50 gees in 6 degrees.
2. I have one land in pieces on one occasion.
3. You cannot tell at a glance whether the switch is on or off. You should be able to tell by listening, but as we get older hearing those beeps gets harder.

I do like several of the screw switches that are out there and I really like solid state switches, like Featherweight or Eggtimer sell.

 

[DaHabes]

I use the Lab Rat pull-pin switches in series with Eggtimer WiFi switches (or Quantums/Protons/Quasar). Pull the pin before you raise the rail (no ladders), arm from a distance. Safety first.

 

[Buckeye]

I use the Lab Rat pull-pin switches in series with Eggtimer WiFi switches (or Quantums/Protons/Quasar). Pull the pin before you raise the rail (no ladders), arm from a distance. Safety first.

What's the purpose of the pull pin switch?

 

[mtnmanak]

What's the purpose of the pull pin switch?

I also put a switch on my Eggtimer computers that have WiFi. I can't speak for anyone else, but my reasoning is to save the battery. Part of it is that the WiFi module can really burn up a battery quickly, but, moreso, I prefer to prep my rockets as much as possible before I get to the field - sometimes days before. That includes prepping the ebay and closing it up. By having a switch, I can prep 90% of the rocket before I show up, finish up the last 10% at the field without opening up the ebay and bring the rocket out to the pad. This is especially important to me at big, multi-day launches where I may bring a lot of rockets.

 

[DaHabes]

I also put a switch on my Eggtimer computers that have WiFi. I can't speak for anyone else, but my reasoning is to save the battery. Part of it is that the WiFi module can really burn up a battery quickly, but, moreso, I prefer to prep my rockets as much as possible before I get to the field - sometimes days before. That includes prepping the ebay and closing it up. By having a switch, I can prep 90% of the rocket before I show up, finish up the last 10% at the field without opening up the ebay and bring the rocket out to the pad. This is especially important to me at big, multi-day launches where I may bring a lot of rockets.

That is the other reason I use the pull-pin switch. Like I said in my post above, you pull the pin to let the juice flow, but don't arm the altimeters via the WiFi switch until you are well away from the launch pad. At the field all I have to do is add the BP to the charge wells, everything else is done - batteries charged, e-matched installed, continuity validated on the bench.

It also completely avoids the confusion from a couple of years ago when there were proposed changes to the Tripoli regs that "required" a hard disconnect - it seemed for a while that WiFi switches alone might not be allowed. I baked that issue into my AV-Bay design and never looked back.

Some will say you are adding more connection points to the design and hence more failure points. There is truth to that, but good components and craftmanship limits the impact. I use terminal connectors that are crimped, lightly soldered and shrink-wrapped for connections made to through the bulkhead screws, crimped and shrink-wrapped ferrules for connections made to terminal blocks, and JST connectors for power connections, then fully bench test everything. Seems to work just fine.

 

[loopy]

I wouldn't mount push button switches externally as it's too easy for things to bump them during recovery and possibly shut them off. I have push buttons internally mounted on a couple of my DD birds, and they switches are very stout to keep them from arming/dis-arming without me pushing them with a screwdriver.
Lately, I've been using the screw switches from Missileworks. I mount them internally, and they work great!