altusmetrum May 2021

altusmetrum@lists.gag.com

14 participants
7 discussions

Does Telemetrum play well with other altimeters for redundant dual-deploy?

by burnwuffie＠aol.com

In particular, does a Telemetrum transmitting on 70 cm. interfere with a Perfectflite Stratologger SL-100? Anyone have any experience? Also saw a video about a "lightning bug" dual-deploy altimeter (https://www.youtube.com/watch?v=IroVZC5ZbF4&t=10s) that uses a step-up transformer to produce an arc that lights charges without e-matches. Interesting, but I wonder how well that would work with a Telemetrum in the same rocket.

1 year, 10 months

Seeking accelerometer flight data for a rocket similar to a Wildman Mach 2

by David Andreatta

(My apology. This was initially sent in html and "scrubbed". Trying again...) Howdy, all; I'm experimenting with some reinforced 3d printed recessed charge well av-bay end caps for a Wildman Mach 2. I'm trying to understand the actual forces encountered by the av-bay hardware during deployment, i.e. actual v.s. simulated. I typically fly with chute configurations where the rocket is descending under drogue at around 70 fps and is slowed very quickly at main deployment to around 16 - 20 fps. Within simulation, this results in a 25 G deceleration over a very short period of time, i.e. a deceleration "spike". In reality, the main chute takes more than 0 seconds to deploy so that the actual deceleration encountered may be significantly less or, let's say, lower magnitude spread out over a long time. In designing these end caps, finite element analysis shows that they have tolerable deflection and should survive without any problems. However, FEA on a 3d printed object is somewhat misleading as most FEA assumes the material is homogeneous, for example machined from a solid block of PET. When 3d printed, various effects yield a somewhat heterogeneous material due to extrusion imperfections, inclusion of air at the layer interfaces, and less than perfect cohesion between the layers. This reduces the overall strength of the material and can affect just how brittle it is as well, but just "how much" for a given object is unknown. I'm slowly working up some prototypes and have created a rig where static and dynamic "drop" tests with a representative mass can achieve loads similar to deployment on the av-bay internal structure and its end caps. I'll be flying with a TeleMega and have had great success with these in larger rockets with "conventional" av-bay end caps. So, while this is a bit off topic, I'm hoping the community may be willing to share some simulations and flight data for similar rockets. For example, if you have and are willing to share BOTH a simulation model (and simulations) in either Rocksim or OpenRocket AND accelerometer data from a rocket with similar flight characteristics, that could be especially useful to me. I'm hoping to see 1) what deceleration is indicated under simulation for the drogue to main transition and 2) how close is that to what was actually logged by an AltusMetrum product (.eeprom file). Yes, I realize that because the data is sampled, the system and resulting eeprom file may not contain the instant of maximum deceleration actually encountered by the airframe. However, I can learn a lot just by observing the shape and extents of the deceleration curve. That would allow me to get some confidence in whether my drop tests are actually similar to what's experienced in flight, or not, and would drive the design and build to completion (or abandonment). Again, I'm looking for information on rockets / flights with the following characteristics: Total mass around the range of 57 oz (w/ H283ST) to 122 oz (w/ K375NW) Descent under drogue around 70 fps Descent under main around 16 - 20 fps Since this is all about deployment loads, your rocket doesn't have to be as fast or go as high as a Mach 2. In fact, if there are both simulation AND flight data, just about anything close will work as I'm mostly interested in the difference between simulation and reality. I expect both "much larger" and "much smaller" rockets have other factors, like body drag, etc., which will make the comparison less relevant so I'm hoping to find something similar in size / mass to the Mach 2. Anyway, if you're able to help, I'd appreciate it! I don't know how interested the list is in this topic so it's your call as to whether you reply direct or via list. Either way, thank you, all, in advance. Clear Skies, Dave Andreatta TRA #19131 WD0HXN Erie, CO

1 year, 10 months

TeleGPS issues

by Charles L Hakes

A brand new TeleGPS I just got (SN 7445) does not save any data. There is only a single ~3 second “flight" out of some back yard near Colorado Springs. I thought it could have been user error the first time I flew it, but it just went up for the second time with the same results. Also, right after launch it says “GPS lost” and there is no telemetry for several seconds, and then it picks up the flight, but the TeleGPS program reports a new starting altitude so the altitude and apogee on the Status screen are way off. The location and maps work. The most recent files are attached. Any ideas on this one? Some way to configure or fix it locally? Or does it need to be sent in? Charlie

1 year, 10 months

GPS for Launch Site

by Ed Chess

Hi Bdale, I'd like to register our HPR launch site in Illinois: Fox Valley Rocketeers (FVR); 042deg 19 min 42 sec N, 088deg 31min 35 sec W; http://FoxValleyRocketeers.org Thanks! Ed Chess

1 year, 10 months

Build trouble

by Jesse Frey

I'm trying to build AltOs on my pinebook pro (ARM laptop) and running into some difficulties. Seems like AltOs, despite being written in java, has some compiled libraries so I can't use the prebuilt binary release. I keep getting hung up on a step that seems to be making icons: nickle led.5c redoff.png Cannot autoimport from file "cairo.5c", giving up. Cannot autoimport from file "cairo.5c", giving up. import Cairo; import Cairo; :1: non-existant namespace Cairo led.5c:21: syntax error before "cr" led.5c:38: syntax error before "led" :1: non-existant namespace Cairo led.5c:40: syntax error before "::" led.5c:41: syntax error before "::" led.5c:42: syntax error before "::" -> set_source (cr, led); led.5c:43: No visible symbol "set_source" in scope -> set_source (cr, led); led.5c:43: No visible symbol "cr" in scope .... There are a bunch more similar errors but they seem to be similar. My googling on these errors hasn't been super helpful. How can I fix these errors? Thanks, Jesse

1 year, 10 months

Seeking accelerometer flight data for a rocket similar to a Wildman Mach 2

by David Andreatta

1 year, 10 months

Altos Droid updated and now crashes - Any suggestions?

by Andy Barwick

Getting ready for the spring flying season and updated Altos Droid to the latest version. Now the app crashes immediately upon opening? "Unfortunately, Altos Droid has stopped." is the only error i get. Tablet is a Samsung Galaxy Tab A (2016) The Android version is 5.1.1. I tried a factory reset and reinstalled AD but no change. Other than the update I'm not aware of any other changes to the device and Altos Droid used to run flawlessly prior to the update. Anyone have any suggestions? Andy Barwick

1 year, 10 months

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

altusmetrum May 2021