Help choosing electronics for my 29mm altitude project

[Neutronium95]

After a getting back into rocketry, I got bitten by the altitude bug again, so I decided to revisit my 29mm high altitude two stage rocket. I think that I have most of the design for the new one figured out in broad terms, so I'm going to start working on building a testbed rocket out of more conventional materials to test out the electronics and deployment sequence. This means that I have to settle on the electronics now.

If all goes well, I might put a 38mm stage under the two 29mm stages, which would in theory get me to altitudes well in excess of 30,000 feet. Because of the GPS tracker requirements for setting Tripoli records, that pretty much narrows my tracker down to either the Featherweight tracker, or the Telemetrum. If I use the Featherweight tracker, I can quite easily pair it with a Raven 4, due to their shared footprint. The Telemetrum could be paired with the new Altus Metrum Easytimer, which would give me tilt inhibition of the staging, which feels simpler than relying on speed and altitude lockouts on the Raven. Ultimately, I care most about reliability. Assuming a competent installation and setup, which avionics package do you think would more reliably control flight events and track multiple stages?

 

[OverTheTop]

Does the featherweight do tilt detection? That would be a deal-breaker for me.

I have both systems, Featherweight and Altus Metrum, and have used the TeleMega to 37500' on a two-stage flight. Very happy with the hardware and configurability. I have only used Featherweight for regular single-stage flights so far, so my experience using them for staging is limited.

Make sure that system mass is a prime consideration, given that you are shooting for altitude.

 

[cerving]

I would recommend using separate electronics for tracking and deployment in a project like that, so that should make getting your electronics into a 29mm airframe somewhat easier (although it will take up more length).

 

[manixFan]

The Featherweight tracker can fit into a carefully designed 29mm nosecone, and can go to 30,000' without breaking a sweat. The Raven powered by a small 180mAh Lipo makes for a tiny package. The A/V bay that Adrian sells is perfect for what you want to do, but of course due to an ill-conceived ban on magnetic switches by TRA it would have to be modified for use. The Raven does not have tilt-inhibit, so that is a consideration, but it has extensive programming capabilities so you can configure it to light the upper stage only under a very narrow set of conditions.

I second Chris' recommendation to use separate electronics for deployment and tracking for small projects. If you are comfortable building electronics kits he may have some recommendations for you as well.


Tony

 

[Cameron Anderson]

The Featherweight tracker can fit into a carefully designed 29mm nosecone, and can go to 30,000' without breaking a sweat. The Raven powered by a small 180mAh Lipo makes for a tiny package. The A/V bay that Adrian sells is perfect for what you want to do, but of course due to an ill-conceived ban on magnetic switches by TRA it would have to be modified for use. The Raven does not have tilt-inhibit, so that is a consideration, but it has extensive programming capabilities so you can configure it to light the upper stage only under a very narrow set of conditions.

I second Chris' recommendation to use separate electronics for deployment and tracking for small projects. If you are comfortable building electronics kits he may have some recommendations for you as well.


Tony

The magnet ban isn't a blanket ban as far as I understood it, it just limits what prep you can do at your table versus the pad (when charged and batteries can be hooked up).
The Raven4 with the av bay is a great idea because of the size, and the velocity and altitude lockouts provide a great margin of safety for stating. With that said, I just bought the Easytimer (my first Altus Metrum product) and was shocked how small it is.

 

[cerving]

The magnet ban isn't a blanket ban as far as I understood it, it just limits what prep you can do at your table versus the pad (when charged and batteries can be hooked up).
The Raven4 with the av bay is a great idea because of the size, and the velocity and altitude lockouts provide a great margin of safety for stating. With that said, I just bought the Easytimer (my first Altus Metrum product) and was shocked how small it is.

The recent ruling is that electronic switches must be backed up with a physical switch, until the rocket is on the rail and vertical. There is a minor exemption for remotely operated electronic switches... you may activate them prior to being on the rail, once you are away from the RSO/LCO area.

 

[Neutronium95]

Thanks for the input so far. I'm still leaning towards the Featherweight option, unless I hear a compelling argument for the Altus Metrum package, especially in regards to more reliable tracking.

I actually do have an old Featherweight avbay, but I don't think that I will use it. I need to cram in a tracker and battery, and it would require modification to make a mechanical switch work.

 

[Cameron Anderson]

You ever looked at the Entacore AIM XTRA 2.0?
Tilt staging, active telemetry, 4-event capable, with GPS tracking. I love mine.

 

[Neutronium95]

You ever looked at the Entacore AIM XTRA 2.0?
Tilt staging, active telemetry, 4-event capable, with GPS tracking. I love mine.

That was actually my first choice, unfortunately it can't fit into a 29mm coupler, which is a major design constraint.

 

[Cameron Anderson]

That was actually my first choice, unfortunately it can't fit into a 29mm coupler, which is a major design constraint.

The telemega is wider than the XTRA. If you went Altus Metrum, you'd need the easytimer, easymini, and the teleGPS.
Make your life easier and go Raven 4 and Featherweight GPS.

 

[Neutronium95]

The telemega is wider than the XTRA. If you went Altus Metrum, you'd need the easytimer, easymini, and the teleGPS.
Make your life easier and go Raven 4 and Featherweight GPS.

My planned configuration of Altus Metrum products was a Telemetrum paired with an EasyTimer. I'm not sure if I can fit them into a tube side by side like I can with the Featherweight products.

That said, I have been leaning towards the Featherweight combo, and I haven't seen anything to indicate that it would be less reliable than the Altus Metrum electronics.

 

[Cameron Anderson]

My planned configuration of Altus Metrum products was a Telemetrum paired with an EasyTimer. I'm not sure if I can fit them into a tube side by side like I can with the Featherweight products.

That said, I have been leaning towards the Featherweight combo, and I haven't seen anything to indicate that it would be less reliable than the Altus Metrum electronics.

I haven't used any Altus products but I have flown the Raven4 probably 10 times with no issues. Small, sturdy, dependable, easy to program and download files. I literally got my Featherweight GPS three hours ago in the mail and have been walking around the neighborhood feeling it out and I have no complaints thus far. I'm flying it Saturday on an H to G two-stage that sims to 7,000 so it will be a legit first test.

 

[Not Quite Nominal]

You ever looked at the Entacore AIM XTRA 2.0?
Tilt staging, active telemetry, 4-event capable, with GPS tracking. I love mine.

Does it require a ham license to use in the US?

 

[Cameron Anderson]

Does it require a ham license to use in the US?

Yes it does. But it's worth it.

 

[n27sb]

The telemega is wider than the XTRA. If you went Altus Metrum, you'd need the easytimer, easymini, and the teleGPS.

How wide is the AIM Extra?

 

[Cameron Anderson]

30mm x 100mm, largest antenna adds another 115mm