Minimum Diameter HED Altimeter + GPS setup

[yvanthesaxophonist]

I'm looking to build a Wildman Mach 2, but before I pull the trigger and get it, I want to think about how it's coming down. Ideally I have dual redundant dual deploy with two altimeters, and a GPS for tracking because this bird is going a couple miles on most motors I'd fly. However, having built in a 2.56" bay before, I don't think it all fits. I have a MW RRC3 and a Blue Raven for deployment, and a Featherweight GPS for tracking, and that didn't all fit in the 2.56", I cheated and put the GPS in the nose cone. The Mach 2, however, is head end dual deploy. This means I can't (easily) put a GPS in the nose.

So, I'm looking for solutions. I have a Quasar that's altimeter + GPS, but it's longer and wider than the RRC3, which barely fits in the 2.56" with the Raven next to it. I have seen some people print bulkheads with a little recess for GPS antennas. I'm sure I could figure it out, but I have no experience doing that, and the fit remains tight. What are my options? I could pick up a smaller altimeter but the RRC3 isn't causing problems, it can take the whole vertical on one side, but stacking Raven and the GPS is problematic.

 

[Buckeye]

Easy solution: one altimeter

Here is my SLCF and FW GPS setup in the Mach2:

https://www.rocketryforum.com/threads/wildman-mach2-hed-recovery-gear.165178/post-2167818

 

[yvanthesaxophonist]

The engineer in me says not having redundant systems is inadvisable. I suppose continuity checks can mitigate risk, but it's just nerve-racking.

 

[mikec]

The engineer in me says not having redundant systems is inadvisable.

I've never flown redundancy in a 54mm MD, FWIW. The RRC3's large size is not doing you any favors, if you really want the redundancy. Find a smaller altimeter?

 

[yvanthesaxophonist]

I've never flown redundancy in a 54mm MD, FWIW. The RRC3's large size is not doing you any favors, if you really want the redundancy. Find a smaller altimeter?

It sure doesn't. Don't really like throwing money at problems to make them go away but you know, it works. I'll definitely keep that in mind, probably need a 4th altimeter anyways for a two stage project I've got planned for after this.

 

[tfish]

I'm looking to build a Wildman Mach 2, but before I pull the trigger and get it, I want to think about how it's coming down. Ideally I have dual redundant dual deploy with two altimeters, and a GPS for tracking because this bird is going a couple miles on most motors I'd fly. However, having built in a 2.56" bay before, I don't think it all fits. I have a MW RRC3 and a Blue Raven for deployment, and a Featherweight GPS for tracking, and that didn't all fit in the 2.56", I cheated and put the GPS in the nose cone. The Mach 2, however, is head end dual deploy. This means I can't (easily) put a GPS in the nose.

So, I'm looking for solutions. I have a Quasar that's altimeter + GPS, but it's longer and wider than the RRC3, which barely fits in the 2.56" with the Raven next to it. I have seen some people print bulkheads with a little recess for GPS antennas. I'm sure I could figure it out, but I have no experience doing that, and the fit remains tight. What are my options? I could pick up a smaller altimeter but the RRC3 isn't causing problems, it can take the whole vertical on one side, but stacking Raven and the GPS is problematic.

Have you considered a 3 sided (triangle) electronics board? I've been using 1/4" Basswood and 2/56 Dubro allen head screws..pretty simple and easy things to work with.

Tony

 

[yvanthesaxophonist]

Have you considered a 3 sided (triangle) electronics board? I've been using 1/4" Basswood and 2/56 Dubro allen head screws..pretty simple and easy things to work with.

Tony

I have not, do you usually pair that with three pieces of all thread? Sounds pretty doable, although I'd want to model that in CAD to make sure I've got the clearances for some of the taller parts of the boards.

 

[tfish]

I have not, do you usually pair that with three pieces of all thread? Sounds pretty doable, although I'd want to model that in CAD to make sure I've got the clearances for some of the taller parts of the boards.

just a single piece of all thread up the center. The 'boards" only have to be wide enough to screw the items down to.

Tony

 

[tfish]

sort of like the second photo.

https://www.rocketryforum.com/threads/telemega-antenna-question.175983/
Tony

 

[yvanthesaxophonist]

sort of like the second photo.

https://www.rocketryforum.com/threads/telemega-antenna-question.175983/
Tony

Every day I find more reasons to own a 3D printer...more money at more problems I guess. But that's very good, the sort of clever solution that let's me have my cake and eat it too!

 

[DarthMuffin]

I fit two eggtimer Quarks with magnetic switches, two 300mah batteries, an Altus TeleGPS and it's 800mah battery in my Mach 2 bay. It wasn't that hard. Wiring everything up for a flight is hard though. There wasn't room for terminals on the bulkheads so I run the wires straight through to the Quarks. Did not use a threaded rod, just ran the kevlar line straight through with a knot on one bulkhead and a tiny clamp on the other.

I used a streamer for a drogue, and probably could have gone drogueless (it's the CF version). Based on that knowledge, maybe you could put the drogue (or a streamer, or nothing) in the nosecone and main down below?

 

[yvanthesaxophonist]

I fit two eggtimer Quarks with magnetic switches, two 300mah batteries, an Altus TeleGPS and it's 800mah battery in my Mach 2 bay. It wasn't that hard. Wiring everything up for a flight is hard though. There wasn't room for terminals on the bulkheads so I run the wires straight through to the Quarks. Did not use a threaded rod, just ran the kevlar line straight through with a knot on one bulkhead and a tiny clamp on the other.

I used a streamer for a drogue, and probably could have gone drogueless (it's the CF version). Based on that knowledge, maybe you could put the drogue (or a streamer, or nothing) in the nosecone and main down below?

The Quark is a tiny board, so I'm sure that helps. I like to have data logging, it's neat, it helps identify problems, and there's a 6DOF that's begging for flights to validate it; the Quark doesn't have any of that. Two Quantums might do it though, since you don't NEED a switch, but I'd have to check with my local club.

 

[watheyak]

The engineer in me says not having redundant systems is inadvisable. I suppose continuity checks can mitigate risk, but it's just nerve-racking.

There's been some spirited and entertaining threads arguing the pros and cons of redundancy here on TRF.

You can make a solid argument that redundant altimeters are inadvisable due to the added complexity and increased points of failure. Especially if you're using two different altimeters and trying to decipher all the beeps. Or, if you use two of the same both could fall prey to the same error.

"The more you overwork the plumbing, the easier it is to stop up the drain, Captain."
-Mr. Scott

There, straight from an engineer. Starfleet, even.

In the interest of transparency, I should mention that I'm just playing devil's advocate here. My current minimum diameter project has two Ravens, but it's 4" diameter. All of my smaller MD projects have had just one altimeter.

 

[yvanthesaxophonist]

There's been some spirited and entertaining threads arguing the pros and cons of redundancy here on TRF.

You can make a solid argument that redundant altimeters are inadvisable due to the added complexity and increased points of failure. Especially if you're using two different altimeters and trying to decipher all the beeps. Or, if you use two of the same both could fall prey to the same error.

"The more you overwork the plumbing, the easier it is to stop up the drain, Captain."
-Mr. Scott

There, straight from an engineer. Starfleet, even.

In the interest of transparency, I should mention that I'm just playing devil's advocate here. My current minimum diameter project has two Ravens, but it's 4" diameter. All of my smaller MD projects have had just one altimeter.

Well, one of them is a Blue Raven, so that'll tell me what's wrong if anything is. Only beeps I have to decipher are the RRC3's. If it works for many people I can definitely try it though.

 

[OverTheTop]

I normally run two Ravens in the middle of the rocket and a TeleMega in the NC. The NC gets blown off at apogee by the TeleMega. The two redundant Ravens blow the main out of the airframe when needed, and if the NC is still attached due to a TeleMega problem they also blow the nose off. So two levels of redundancy in HED.

 

[yvanthesaxophonist]

I normally run two Ravens in the middle of the rocket and a TeleMega in the NC. The NC gets blown off at apogee by the TeleMega. The two redundant Ravens blow the main out of the airframe when needed, and if the NC is still attached due to a TeleMega problem they also blow the nose off. So two levels of redundancy in HED.

How do you put a TeleMega in the NC with HED?

 

[OverTheTop]

How do you put a TeleMega in the NC with HED?

If the Ausrocketry forum was up I could point you to some pictures. Let me dig a little...

 

[cerving]

Putting an antenna in a HED AV bay can be tricky, however you may want to think about having the antenna pointing down into the drogue bay instead of up into the NC bay with the main chute. There's usually a lot more room there. You can use an external antenna screwed onto the lower bulkplate, or you can have the antenna poking out from the lower bulkplate... if you do that, be sure to seal the gap with some RTV or similar sealant.