4" to 3" 2 stage to 100k

[Hobie1dog]

Yep. I'm so out of my league here I feel like a kid in Teeball watching a pro baseball game. And yet I'm loving it. Please keep posting!

+1 We are not worthy

 

[FredA]

but then the sustainer ignition wires have to be broken on chute deployment.

Use a wireless link to light the sustainer - no wires to break.
Works great!!!

MARSA GADGETS

 

[Chad]

Use a wireless link to light the sustainer - no wires to break.
Works great!!!

MARSA GADGETS

I've thought about that. Also, my sustainer is ignited from an Atrus Metrum EasyTimer so i've also thought about just sticking it and another small lipo in the motor mount somewhere. That way sustainer ignition lives with the motor while recovery lives in the nosecone. Seems logical to my sporadically logical brain.

 

[ChuckH]

How are you planning to do sustainer ignition? head-end? In my two stage design i have the sustainer electronics mounted in the nosecone but then the sustainer ignition wires have to be broken on chute deployment. I have a deans connector that seems to be ok with being jerked apart by the ejection charge but it's not my favorite part of the design.

FWIW, I've used a 2 pin Molex connector for this purpose for over 15 years with no issues.

 

[FredA]

FWIW, I've used a 2 pin Molex connector for this purpose for over 15 years with no issues.

I hear ya - me too - but since you always are crossing a parachute bay with the wires I sweat them becoming unplugged when you pack the chute or when the chute settles under acceleration.
Since I always turn OFF any pyro-checks on an ignition output, I'm left wondering come launch time.
With the items noted there is one less thing to worry about.
Love these - makes for a tiny package on top of the sustainer motor when used with HEI.

 

[Buddy Michaelson]

We aren't planning on messing with head end just yet. The current plan is to run flat speaker wire to the aft end of the motor for the separation charge and air start. We were originally planning on having some sort of wire disconnect, but didn't really like the idea of it so we switched to doing all of the recovery out of the nosecone.

Can you run your electronics ontop of the forward closure and run your wires upwards instead? I’ve been using pull connectors that split upon deployment, but taped to stay together with high G’s, they’ve worked well everytime, and every rocket has multiple.

 

[anbhtblr]

The internal tube in the original transition was not installed straight enough and resulted in about a .7 degree deflection angle between the stages. We are worried that this may cause undue stress or induce a spin/corkscrew during the portion of the flight that's they stages are connected. Despite only being about 4 seconds of flight, it's better to be safe than sorry.
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We are making a whole new transition and tube. The transition is curing, and the tube will be started shortly.
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Like last time, the shrink tape on the tapered section does not sit nicely and needs to be made of many tiny strips. If anyone knows of a better way to do this, please let me know.

The ebay is also coming along nicely. Some edits need to be made to fit the cameras correctly, but so far there are not any major edits needed.
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It is worth noting that, unlike previous models, the RunCam Split HD requires a BEC stepdown to 5V when running off of a 2s LiPo. It will not turn on otherwise, which I have not found in other models like the Split 3 Micro.

I've found that operational stability of both the Split 3 and Split 4 is voltage sensitive.

 

[Bean74525]

Small update: the motors for the first launch this winter have arrived. L1355 to a K456 is going to go 13k ft and mach 1, so it should be a fun first flight.

 

[Buddy Michaelson]

Small update: the motors for the first launch this winter have arrived. L1355 to a K456 is going to go 13k ft and mach 1, so it should be a fun first flight.

Thats awesome! What’s your plan on separation charge, and time between separation after burnout and ignition?

 

[Bean74525]

Thats awesome! What’s your plan on separation charge, and time between separation after burnout and ignition?

We're probably going to have a sep charge on this flight, but I'm not entirely sure if its necessary. Its going to be coming down from the sustainer ebay, so less wiring would be nice. Right now I've been simming with a 5 second delay assuming an actual 3 second programmed delay with 2 seconds for the motor to come up to pressure. I'm a bit tempted to up this a little after seeing the delay on Kip's flight though.

 

[plugger]

I'm curious to see if a step down in diameter between booster and sustainer would be enough to incur drag sep without requiring a charge. From my limited experience staging to the same diameter does not incur a drag sep and a charge is needed to coast sans booster.

 

[jderimig]

Why would you want to separate the sustainer if it doesn't want to dynamically separate? That would lose altitude.

 

[plugger]

Why would you want to separate the sustainer if it doesn't want to dynamically separate? That would lose altitude.

to not light the sustainer motor with the ISC still attached and to keep the flight low to stay within ceiling.

 

[AlexBruccoleri]

Why would you want to separate the sustainer if it doesn't want to dynamically separate? That would lose altitude.

In the case where the coupler has zero friction, you are correct that *not* dynamically separating means compression. If the joint is tight, for structural purposes, then it could be under tension and still stay together, which would reduce altitude.