how to break wires?

[Buckeye]

I am planning my first 2-stage HPR build and learning. I want to use a 4-channel Raven in the sustainer payload to control all the events: separation charge, sustainer motor ignition, sustainer drogue, sustainer main. When the sustainer drogue fires, the wires to the separation charge and motor igniter need to give way. How do you enable that to happen?

 

[rharshberger]

could be as simple as a shorted plug on one part and the regular plug on the other, when they pull apart, the conditions are met and the circuit is open. A red JST connector like used on 1 and 2S Lipos would work, modify to make separation easier.

 

[Titan II]

#1 with a small piece of tape folded over it.

 

[rharshberger]

#1 with a small piece of tape folded over it.

View attachment 562679

He's asking for a breakwire not a splice, the breakwire is a type of go/no condition for sustainer ignition, if its broken (open) the sustainer has separated from the booster and can light, if its not (closed circuit) the second stage is inhibited and will not fire. Plugs are easier to "tune" for reliable separation, wire twisting (like #1 splice) can work but its harder to get consistent results with. A JST plug with the male side sanded to be a light resistance pull out is ideal, easy to use. I saw in individual build the two parts of the JST into the joint between the ISC and the sustainer, the shorted male plug was epoxied into the top of the ISC protruding enough to engage the female part epoxied into the rear of the Sustainer.

 

[Titan II]

Plugs are easier to "tune" for reliable separation, wire twisting (like #1 splice) can work but its harder to get consistent results with.

Disagree. It is not at all hard to have 100% conductivity when needed, and 100% separation, when needed. I have done both methods.

 

[tim cubbedge]

#1 with a small piece of tape folded over it.

View attachment 562679

I use (1) for all break wires. Have seen others use (3)

 

[Buckeye]

I am not necessarily looking for go/ no go logic at this point. Just a way to connect two wires that can pull apart easily.

 

[VernK]

I am not necessarily looking for go/ no go logic at this point. Just a way to connect two wires that can pull apart easily.

I suggest Deans Connectors. They make very good (low resistance) electrical connections that can carry a lot of current if necessary for igniters yet they are easy to pull apart. Readily available from Amazon and other places.

 

[JimJarvis50]

I use Deans Plugs too, a different version though. I like them because I can file the prongs to get just the separation force that I want.

Jim

 

[James Duffy]

+1 on the pull-plug idea that others have suggested. An early version of my Little Joe used a similar setup for launch detect.

 

[Egoldee]

This is from someone else but I have use this method successfully at least 4 times:
Pictures of break-wire setup enclosed. Strip about 2½ inches of insulation from each wire. I LIGHTLY apply masking tape lengthwise to each break-wire for insulation—lightly so that the wires will easily separate once the ejection charge fires.

 

[Handeman]

I highly recommend you read the article "The Spectral of Staging" by Fred Taverni. It's in Tripoli High Power Rocketry magazine Volume 33, numbers 1, 2, & 3.

Fred has launched 5 stage HPR rockets and has a great way to separate the wiring when stages deploy. He explains it as Staging Umbilical starting on page 53 of Vol 33, No. 2.

 

[kjhambrick]

I use Deans Plugs too, a different version though. I like them because I can file the prongs to get just the separation force that I want.

Jim

@JimJarvis50 --

I know that you recommend and fly a zipperless coupler, so where do you locate that bundle of plugs axially along the sustainer airframe ?

Thanks !

-- kjh

 

[JimJarvis50]

@JimJarvis50 --

I know that you recommend and fly a zipperless coupler, so where do you locate that bundle of plugs axially along the sustainer airframe ?

Thanks !

-- kjh

I run wires with the plugs on them through the drogue bay with a foot or two of extra wire. There is perhaps a few inches of wire sticking up from the zipperless coupler with fittings that mate those coming down through the drogue bay.

Jim

 

[SolarYellow]

The pullout force on header jumper connectors is generally pretty low, but they should make good connections for low to moderate power requirements.

https://www.amazon.com/Solderless-Multicolored-Electronic-Breadboard-Protoboard/dp/B09FP9M5J9/?th=1
D-sub pins are also available individually. They are available in both sheet stamped versions and machined versions. Pull-apart force is generally a little higher than header jumpers.

https://www.amazon.com/Jienk-200PCS-Female-Crimping-Connector/dp/B09HCBVK6F/
https://www.amazon.com/JRready-Terminal-Connector-205089-1-contacts30/dp/B09BZ789HJ/

 

[kjhambrick]

Thanks Jim !

I recalled seeing a picture or maybe it was a video where you slide your drogue bay up inside the upper airframe and then it is screwed thru the wall via cap screws.

I looked for a picture but have not found it ( yet ).

What matters is there is an open tube located above the zipperless coupler and the bundle of plugged cables are inside that tube where they can do their disconnect magic when the drogue is deployed.

-- kjh

 

[Buckeye]

The pullout force on header jumper connectors is generally pretty low, but they should make good connections for low to moderate power requirements.

https://www.amazon.com/Solderless-Multicolored-Electronic-Breadboard-Protoboard/dp/B09FP9M5J9/?th=1

I threw a pack of these in a recent Amazon order to give them a try. Just lightly pulling the wires with my fingers easily separated these connectors. A little too easy, imo.

I am gonna go with Post #3 Figure #1.