Stratologger CF

[HJRocketTeam19]

Hi, I am new to model rocketry and have purchased the Stratologger CF. It lists in the manual that for example you can deploy at 700 feet. But is that at 700 feet after apogee? Or is it 700 feet from the ground?

 

[tim cubbedge]

700’ above ground. Can be changed thru the software if you have the required USB adapter.

 

[Jim Hinton]

For what it's worth, I use that altimeter with that same default programming in my PML AMRAAM 4. That programming works great in the AMRAAM.

Jim

 

[HJRocketTeam19]

Thank you so much!

 

[Bat-mite]

Just as a little tutorial, barometric altimeters use atmospheric pressure to calculate altitude, since air thins as it gets farther and farther from the ground. The altimeter samples the pressure and calculates the altitude as the rocket goes up. At apogee, when the rocket is arcing over, the altitude is staying consistent. That tells the altimeter that you have reached apogee and it is time to fire a drogue charge.

On the way down, when the rocket reaches the preset altitude, it knows to fire the main charge. Also, there are safeguards built in to make sure the rocket is ascending before it will fire a charge, so that you don't get an apogee charge while stored on the ground.

 

[manixFan]

Something to keep in mind when setting the deployment altitude is how long it takes your recovery harness and chute to fully deploy. For smaller rockets a lower altitude may be sufficient but for larger rockets you'll want to choose a higher altitude to give everything a chance to unwind. Same on windy vs. calm days - on windy days you may want to set deployment lower to minimize drift.

I generally like to set my main deployment altitude fairly high if I think I will loose sight of it as the higher altitude gives me more time to get a visual on the chute. If you are using a tracker a slightly higher altitude may also give you more time to get a good fix on the tracker under a stable chute.

Over time you'll figure out what works well for you and your setup. Another big thing is to make sure you completely understand how the wiring works and that your setup won't be affected by the stresses it will be subject to under flight conditions.

Good luck,


Tony

 

[Bat-mite]

Something to keep in mind when setting the deployment altitude is how long it takes your recovery harness and chute to fully deploy. For smaller rockets a lower altitude may be sufficient but for larger rockets you'll want to choose a higher altitude to give everything a chance to unwind. Same on windy vs. calm days - on windy days you may want to set deployment lower to minimize drift.

I generally like to set my main deployment altitude fairly high if I think I will loose sight of it as the higher altitude gives me more time to get a visual on the chute. If you are using a tracker a slightly higher altitude may also give you more time to get a good fix on the tracker under a stable chute.

Over time you'll figure out what works well for you and your setup. Another big thing is to make sure you completely understand how the wiring works and that your setup won't be affected by the stresses it will be subject to under flight conditions.

Amen to that! Here is a video of one of my rockets with a 50# descent weight. Main was set for 1000'. Tookk about 400' of free fall to get it fully open. Had I set it for 500', that could have been catastrophic!

 

[manixFan]

Amen to that! Here is a video of one of my rockets with a 50# descent weight. Main was set for 1000'. Tookk about 400' of free fall to get it fully open. Had I set it for 500', that could have been catastrophic!

Wow, great flight and video! Really cool that we can see the whole flight and deployment. It looks like your total shock cord length is at least 50', which also requires a higher main deployment. I did like how softly the chute opened, looked very NASA-ey.

Thanks for posting that, great example overall.


Tony

 

[Bat-mite]

Wow, great flight and video! Really cool that we can see the whole flight and deployment. It looks like your total shock cord length is at least 50', which also requires a higher main deployment. I did like how softly the chute opened, looked very NASA-ey.

Thanks for posting that, great example overall.

A pleasure, and thanks. That's a silk chute with 18 shroud lines, so it gives that nice "jellyfish" effect. Harnesses are 35' and 40', IIRC.

 

[DaveW6DPS]

I like Stratologgers and have used them in many flights. I have rarely seen a reason to change the defaults.

If there are hills in your recovery area that are more than 400 or 500 higher than your launch site it would be prudent to set the main higher.