Featherweight Blue Raven Development Thread: Recorded time-series data

[OverTheTop]

If I did the math right that comes to about 22.5Amps max discharge current, how does the published discharge rate of a lipo compare with your internal resistance metric?

That figure for 75C is usually determined for a certain minimum output voltage to keep everything running. Putting a short on the cell it would likely provide waaay over the 22.5A you calculated, limited only by the resistance of the wires, traces and components in the circuit.

If you are clever you can size the wiring in your circuit to limit the current to acceptable values, by making the wires smaller than would normally be used. This approach can be fraught with problems, as if you get it too thin it can heat up and smoke the insulation or even act like a fuse. Some mains appliances use this technique to limit inrush surges to get within regulatory testing requirements.

 

[Adrian A]

I have some 300mAhrs 1s batteries with 75C printed on the label which I think is really stretching it. 75C is good marketing but i'm not sure the batteries i have can actually deliver that discharge rate. If I did the math right that comes to about 22.5Amps max discharge current, how does the published discharge rate of a lipo compare with your internal resistance metric?

The advertised discharge rate is supposed to be what the battery can put out into a normal load continuously without getting damaged or overheating. The short circuit capability is likely to be much higher than that. A 300 mAhr cell with a 15C or 20C rated capability would be more likely to have appropriate internal resistance to avoid the risk of damaging the Blue Raven’s output FET.

But the only real way to know what the battery is capable of is to measure the current while letting the battery short or discharge into a load around an Ohm or less.

Once I add current limiting to the firmware then that battery should be just fine. But in the meantime I wouldn’t use it for an airstart because the chance of a short is 100% after the motor ignites. A ematch would be relatively low risk because it tends to open up right away, but I think when you’re talking about initiating a small explosion, all bets are off about what happens to your wires immediately afterward.

 

[kjhambrick]

All --

I finally got back in town and updated my Android Phone with Blue Raven Android App version 1.92

After running a few Sims, I also upgraded my simple awk scripts that process the new fields in the high_rate and low_rate files and I added version detection and a Version Stamp at EoR for the incoming data files ( I only recognize versions 1.78 -vs- 1.92 -vs- FIP Data so far ).

My usual whining ... All I've got for Version 1.92 is Sim Data but the Sim Data looks GREAT !

1. Being a Linux geek, I REALLY appreciate the simple text .csv files instead of Excel .xlsx files ( other users may feel otherwise )

2. The new Flight_Time Field in both files is VERY nice. I really like the t-minus times before Liftoff Detect.

3. The new low_rate Baro_Altitude_ASL and Baro_Altitude_AGL fields are very much appreciated !

4. The low_rate Velocity_Up values look good now. VERY NICE ! ( I've not tested the Velocity_DR and Velocity_CR values but I imagine they're OK too )

5. The Adrdoid-Side Graphs are looking good.

I am going to run a Ground Test or two with the Blue Raven over the next few days in my Level 2 attempt Rocket ( Nocturnal Missions ).

But first I need to break out the Walston and practice tracking my 3-year old Granddaughter Evie down at the School Yard so I have a better chance of recovery should I land in the Corn Field ( or worse )

Thanks for the Update Adrian !

-- kjh

p.s. As Adrian said above, I had to uninstall version 1.78 and then install the latest version 1.92 to get the Android App to work ( I skipped version 1.90 ).

p.p.s. I've got parts on the way so I can fly the Blue Raven down at the School Yard with the girls in a Low-Power model Rocket in PayLoad-Only Mode.

That should eliminate my incessant whining about not having any real data to mess with

 

[Earache]

Hi Adrian,

***New Info*** Never mind! I just downloaded the new beta combined app. The firmware updated, the simulation ran, the data downloaded, and everything worked perfectly! I'm all set for my test flights on Saturday.

Earache

***Original Post*** I apologize if this is the wrong forum to ask. I finally got time to start testing my Blue Raven SN 0183. I have App version 1.0.3 (206) on an iPhone 13 mini and the Blue Raven reports Firmware 3a510c7 08/09/2023. On startup I get a message to update the firmware and when I click OK nothing happens. I don't get the screen to select the update file. If I go to the three dots under manage after connecting and choose Update Firmware, I get the dialog to choose the update file. I do so and nothing happens. I tried leaving it on for an hour to see if it was just slow starting up but no, nothing happens. I've tried changing a setting in Deploy and Send to device, and all I get is the spinning Loading... wheel. Live Data eventually appears when I tap on the icon. I've tried running a flight simulation under Set up simulation and hitting Start sumulation. The Live Simulation Screen appears, but other that the time updating every 24 seconds or so, nothing else happens. I've tried looking at the USB output in a terminal simulator, and while I get the 5/second data feed, I can't get any useful information beyond that the phone app has updated date and time. I also can't send any commands that seem to have any effect. What am I doing wrong?

-- Earache