The short and tragic life of a TBS Discovery

R

RTRyder

Merlin of Multirotors
Here's 100 + reasons to retire old battery packs...

IMG_2708a_zps87f1cba3.jpg


First time in the field with my TBS Discovery #2, flew superbly right up to the moment this happened. This time I have video of actual event even though the GoPro got tossed from the frame and ejected the memory card, I was recording the pilot cam view at the ground station which was fortunate mainly because it made finding it a lot easier after watching the video to see what and where it happened.

The TBS frame plates are a total loss, of all the open grassy areas at the field it managed to find the 12 foot wide strip of pavement that runs down the middle as it came down tail first. New TBS Disco kit already on order, have to do a post mortem and see what else beside the broken Graupners needs to be replaced.

More later, have to head out the door in a few minutes to attend a memorial service for my wife's grandfather...

Ken
 



kloner

kloner

Aerial DP
RIP



man, I've crashed a fair bit, seen alot of f450 carnage on here, but these discos just come apart when they auger in. Sorry dude


el taco
 


R

RTRyder

Merlin of Multirotors
I've taken a closer look at it and it appears the total damage is the TBS frame plates, 3 Graupner props, the battery, and 1 arm. Considering it fell end battery first onto pavement and then rolled once or twice stopping just short of submerging itself in 8 inches of water it held up OK, my MK quad sustained far more damage earlier this season when it augered in about 150 feet south of where this one landed.

The cause of the crash was 100% me sort of. I was flying an older 4S 5000 pack that I normally use at the end of the day if I have no more "good" batteries charged. I have 4 of these and use them in pairs wired in parallel on a different frame or for shorter flights using just one to get that one last flight in before packing up to head home. What I didn't realize was how fast it dropped voltage as they dip below 14 volts. I had already seen the low voltage alarm I set in the EZOSD appear on the screen but backing off the throttle brought the reading up a bit and the alarm went away. The next time I saw it pop up again the reading was down to 14 volts so I figured I'd do one more loop around the field and land, I made it about 2/3 of the way and down it went. Looking at the video from the pilot cam I see the voltage reading at 13.2 just as it wobbles a bit and falls backwards to the ground.

Clearly a case of "low voltage cutoff", but what surprises me is how fast the pack went from 14.0 volts to 13.2. Unfortunately I was paying more attention to the current reading and how many mA I had used, I figured the last loop was OK because I had used only a bit over 3200 mA out of the battery rating of 5000, it didn't register in my brain how old that pack is and that it probably wasn't even close to being capable of 5000 mA anymore, lesson learned the expensive way!

Before the crash it was flying SOOOOOO good, I have to say I got two of the best FPV flights I've ever done with a TBS Discovery on this one before it died. The good news is that it won't take that much to fix it, I just hope it flys as well afterward. Next thing is to decommission the other 3 old battery packs and order some fresh Turnigy 4s 5000 to replace them..

Ken
 
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kloner

kloner

Aerial DP
watching there internal resistance helps figure this out when you get old packs like this. they hit 5-6mv a cell, there done. I've lost some really nice scale helicopters screwing up with packs so i understand your pain brutha... you can rebuild it faster, stronger, better. Sometimes it's better to know you caused it versus it just acting up.... sometimes
 


R

RTRyder

Merlin of Multirotors
TBS Discovery #2.5 flew for the first time today, a total rebuild of the crashed #2 into new TBS frame plates. That and a set of 4 new Graupner 8 x 5 props and its back up and flying as well, maybe better, than the original version. I really like those iPower motors, 4mm mainshaft with bolt-on prop adaptors, one took a hard enough hit to put some pretty good gouges in the can and it still spins true. They all do after hitting the dirt hard enough to decimate 3 Graupner props, had those been cheaper motors with 3mm shafts it would be sporting a new set of motors now along with the new frame.

Batteries are all charged and all my FPV gear is packed and sitting by the door for an early AM trip to the field for another try at flight testing the newly rebuilt Disco and also trying out the new MultiWii Mega board with GPS that I currently have mounted on an F450 frame. If the RTH works well enough this may become my new gold standard flight controller for FPV quads, flys beautifully in manual and autolevel mode and tuned right is fully aerobatic which the Naza controllers do grudingly if they don't shutoff the motors and fall out of the sky first! Total cost for the board plus GPS unit is less than the cost of just the Naza GPS unit, a substantial savings on the build cost and a lot more tuneable with open source software, what's not to like? OK they take a lot more work to setup and tune but I'm a cheap SOB at heart and willingly spend hours tweaking settings to save a few hundred $$$ ;)

Time to get some flying in before the big wind storm hits, if the weathermen are right we'll only get the edge of it, if they're wrong we could be in the dark for a few days after a direct hit. I'll have to make sure to stock up on gasoline for the generator tomorrow...

Ken
 



S

Silverwood

Member
Ken, good to hear the Ipower stand up to a good bump...I have been looking at them for my next quad, looks like the price is right for the quality... was wondering which motor size you are using on your Disco?
 

R

RTRyder

Merlin of Multirotors
Silverwood said:
Ken, good to hear the Ipower stand up to a good bump...I have been looking at them for my next quad, looks like the price is right for the quality... was wondering which motor size you are using on your Disco?
Click to expand...


The 2217Q, the smallest ones available with 4mm shaft, bolt on prop adaptors, and can handle 4S. I like them enough that I'm going to swap the other Disco over to them with a set of reflashed ESCs. On 8 x 5 Graupners and a 4S 5000 pack it will fly 12 minutes no problem and it has plenty of power, I was seeing 40 mph crusing speeds on the OSD display this past weekend.

Ken
 

Dale UK

Dale UK

Member
TBS 450 is still the best bird out there for reliable FPV and GoPro without gimbal - glad your replacing not looking for alternatives :frog:

Poo happens - stick with it !!
 

Dale UK

Dale UK

Member
kloner said:
watching there internal resistance helps figure this out when you get old packs like this. they hit 5-6mv a cell, there done. I've lost some really nice scale helicopters screwing up with packs so i understand your pain brutha... you can rebuild it faster, stronger, better. Sometimes it's better to know you caused it versus it just acting up.... sometimes
Click to expand...

Kloner

Hear what you say ..... what's the best kit for measuring the internal resistance of LiPo's ??

D
 

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