Binder Design Excel with Dual Deploy (54mm) build

[Buckeye]

I wonder if the rocket was too complicated for a Cert rocket?

There was a lot of electronic "stuff" in the rocket.

Bob

Regardless, he still had motor backup which also failed. Remove all the electronics, and the result is still the same. Probably.

Not sure why you had 4 altimeters in there, but it's your rocket, not mine. What is most important to you - the "L2" stamped on your card or a challenging electronics project? If it is the former, and your 0/2 lament seems to indicate this, then remove all the bling. If it is the latter, then keep on truckin' and have fun.

 

[chuck5395]

I might be wrong here, but it sounds like all that electronic gear was just along for the ride.
The motor ejection was the primary and only form of deployment for this flight.

 

[woferry]

To be clear, none of the electronics were doing deployment, only logging. I'm really into data collection, so that's why they were all there. My long-term intent was to use the SLCF as a primary deployment system and the EasyMini as a backup, but I've been struggling to find an e-match that actually works. I have a box of 80 MJG Firewire Initiators plus 3 additional ones I purchased from a vendor that all just blow-open without ever catching fire, I've mentioned it on other threads here. MJG has acknowledged to me that they had a 'chemical issue' and will be sending me a fresh box around the end of the month, but that hasn't happened yet. I did order a set of Wildman Ejection Ignitors last week once I learned that they carried some, and they were in my mailbox when I got home late Friday night, but I had no time to ground-test that evening, nor time to test at the field as I went from helping the club and vendor setup to first launch/recovery to L2 test straight to motor installation and the L2 flight. Now in hindsight I should have thrown some BP in the charge well and thrown in one of the Wildman ignitors even without any ground testing, it very well may have saved the rocket (and my L2 cert). But since I hadn't done any ground testing, and didn't have any reason to think that the motor eject would totally fail (that's the first I saw that in my 18 flights so far), I didn't throw any e-matches in. I had debated for a few seconds throwing one in just to see if it burned (do my very first 'ground test' in the air), even if I did that I still hadn't planned on pouring BP in with it so it wouldn't have done any good.

So it was pure motor eject and that's why there were no e-matches, I had no proven-working e-matches yet, just 83 known-bad and 20 completely unknown (but assumed bad until proven good given my past experience). The electronics were all fully-armed, I had a checklist with me and everything beeped-out properly for the flight, of course none of the electronics were rigged for deployment anyhow. The delay grain was fully burned, I could see to the top of the forward closure before removing any of the delay parts. The port in the closure was plugged with a solid piece of BP, and about the bottom-half of the closure charge well was also solid BP, the top-half was loose and poured-out when I tilted the motor after removing the white paper cap. I'm not sure if the parts of the BP that were solid happened during the crash-landing or if that had somehow happened in the time between when I added it and flew the motor about 30 minutes later, I'm assuming it was the landing but I still can't explain why it wouldn't have burned then. But when I cleaned the closure the bits were in the expected places (washer, O-ring and insulator) and the rest had burned away (I didn't notice if the spacer was there or burned away, it might have come out as one piece along with the insulator.

When I was analyzing the ground video I took (not posted online yet but two pictures below) there seemed to be something a bit odd towards the end of the motor burn, it seemed to stop (the white smoke stopped and the motor stopped glowing) and then re-started again ~50ms later (1080p/60 video FTW! Did I mention I like data collection? :wink: ) burning for another 300ms for a ~2.2s total burn, but I wouldn't imagine that had anything to do with the lack of ejection(??). Perhaps by some chance could the delay grain have come out if there was a surge in the motor thrust that late in the burn? Or could whatever temporarily put the motor out have put the delay grain out also, and perhaps it dislodged from the closure and was inside the liner when I disassembled the motor? I still have the pieces at the top of my garbage, I'll take another look at what's in the liner.

 

[Binder Design]

Sorry to see the carnage.

 

[AlnessW]

Do I read correctly that this is a 2nd failed attempt at an L2? Crap...very sorry to hear this.
I agree with some of the people here that it seemed a bit complicated for an L2 rocket, but obviously everyone has different goals. I also find it hard to believe that a tracker could cause that much interference with an altimeter... (Although I know they were just ride-alongs in this instance.)

My only thoughts on the BP not lighting would be perhaps some sort of obstruction in the forward closure well? The fully-burned delay grain could suggest this.

 

[woferry]

Do I read correctly that this is a 2nd failed attempt at an L2? Crap...very sorry to hear this.

The first failure was in the test, I was so busy finishing this rocket and preparing for the trip to the launch that I didn't study at all, got very little sleep, skipped breakfast, [insert other excuses here ] and scored 44/50 (one I got wrong purely by not reading the question thoroughly enough, missing the "unlicensed" word in who a commercial manufacturer can sell a motor to). So I didn't do an L2 flight that day (but it was the rocket's first launch on the I280DM which went great, I flew that before taking the test as there was no way the first flight was going to be the J motor, I wanted a DMS so that I wasn't putting a casing in jeopardy on the maiden flight, though I flew with all the electronics since I wasn't about to not get data on that first flight). Second time I studied and passed (though I still misread a question and got one wrong due to that), and then the failed flight. So only one J motor burned, the J350W-∞. :wink:

I agree with some of the people here that it seemed a bit complicated for an L2 rocket, but obviously everyone has different goals. I also find it hard to believe that a tracker could cause that much interference with an altimeter... (Although I know they were just ride-alongs in this instance.)

Yeah, just ride-alongs that flight, so I don't see how any of that complicated the flight, it just added weight (and dollars lost on impact). The SLCF and EM were to be the standard gear in that rocket, and the EF obviously for tracking. They're far apart from each other and absolutely no sign of interference in my testing. The A2/A3 were because I'm transitioning from the former to the latter, and like also having accelerometer data since the main altimeters are baro-only. Eventually the A3 will fully replace the A2. But as I've said before, I'm all about data. I've recorded every gallon of gas put in every vehicle I've owned for as long as I've owned them, so I have all the mileage data, etc. And I have a spreadsheet that tracks every battery-powered device I own and when I replace the batteries in each. So I'm certainly going to err on the side of more data collection rather than less. So far it looks like I *might* be able to recover data from the EasyMini and the A3, so I'm hoping at least one of those two will at least tell me how high it really went, and perhaps how fast it came down.

My only thoughts on the BP not lighting would be perhaps some sort of obstruction in the forward closure well? The fully-burned delay grain could suggest this.

The well was plugged... with solid BP. I assume that was from the impact, is there some other reason why it would turn into a solid ball just a few minutes after pouring it in? I'm positive the Synco lube was clear of the opening, I lightly grease the O-ring and outside of the insulator rather than the well itself and slide the whole thing in as a set with the spacer already sitting flat in the top of the un-greased well, so there should be no way to get grease anywhere near the opening. I did re-inspect the liner and there's no sign of a delay grain inside it, just the nozzle which wound up inside the liner.


Anyway, kit re-ordered this morning, the rocket will be built again. Hopefully in time for Dairy Aire mid-May. This time I will put a bit less epoxy in the fin can assembly, and try to use some bondo rather than the ~3 coats of filler primer (5 cans of rusto) to get the outside smooth, so hopefully I'll be able to shave a few ounces off at least. And my previous configuration was going to be 2 e-matches but one charge well (since it was the e-matches I don't trust, not so much the BP), now it will probably be two independent charge wells since I really don't trust either at this point.

 

[woferry]

The well was plugged... with solid BP. I assume that was from the impact, is there some other reason why it would turn into a solid ball just a few minutes after pouring it in? I'm positive the Synco lube was clear of the opening, I lightly grease the O-ring and outside of the insulator rather than the well itself and slide the whole thing in as a set with the spacer already sitting flat in the top of the un-greased well, so there should be no way to get grease anywhere near the opening.

Actually, re-tracing my steps here a bit, I've mostly dealt with the DMS motors which have a pretty deep charge well, so you pour the BP in and then insert the red 'rubber thimble' to plug the hole. I have built a few AT RMS motors before, but clearly recall with this one that the BP totally filled the well, so it took a bit of finger sweeping to clear the rim of the closure so that the white "sticky" (yeah, barely) disk could make contact with the closure. This sweeping resulted in a bit of a mound of BP in the middle, so I did (gently) tap the entire assembled motor against the table a few times to help the BP mound flatten before applying the disk and capping it. Could this have jammed-up the opening to the well?? I didn't think anything of it at the time (and suspect I've done it before with the other AT RMS motors I've built, but I can't say for sure), but of course I'm questioning everything now since I still don't know just what I did wrong.

This is the first time I've used this particular closure, the other reloads I've flown this year were with an RAS FFC that I use in my 38/360 case, which again is a bit deeper well than the closure that came with my 38/720 case. But the opening was clearly open when I started, and only plugged with a solid ball of BP when I took it apart afterwards.

 

[AlnessW]

Interesting stuff, thanks for the forensics. Was anything salvageable?
My other idea was that maybe you got grease in your forward closure, but that wasn't the case either...

Glad to hear you'll give it another go - I still have to rebuild my Excel! And I think you're on the right track with the "less epoxy in the fin can" idea.

 

[woferry]

The second picture in post 26 basically shows everything I could salvage above the 7" line. That picture is not totally accurate, one of the magnetic switches below that line looks perfect, the other was involved in the battery outgas/fire event, so it's pretty singed and I haven't tested either one to verify that they still work.

The Mobius looked intact, even when I opened it up, but it doesn't function anymore. I think it's battery and lens mechanism are intact, I have two more on order from HobbyKing (supposedly from their US Warehouse, but I got the 3 replacement batteries yesterday and the Mobius's weren't in that shipment, I suspect they're coming from overseas) so I should have some spare parts for the working ones at least.

Other than a cracked display and a torn-off LCD flex connector the A3 PCB looked intact to me, but I sent it back to Jolly Logic and they said the CPU is torn off its pads so it's unrecoverable. It's coming back to me as I may be able to remove the flash and try to extract the data myself. I did that for the EasyMini and Altus Metrum helped me decode the flash contents and I got a full log of the flight (2556', 277mph max velocity, 25.6s, 210mph at impact).

But the chutes, protectors and shock cords are all fine, the motor casing seems fine also. The lower ring came off the A3854 adapter, but it threaded right back on(??). The outer ring part of the A3854 is bent outwards, as was my Aero Pack threaded retainer (separating those two pieces took some work), I guess the motor tried really hard to get out the back of the rocket as it accordioned, and the paper the JB Weld was attached to on the MMT was the first thing that gave. So I'm not sure if the ring to the A3854 will hold motors tight anymore, I'll probably order a second one just to have another one (I have 3 54mm rockets by summer, so it would be good to have more than one anyway). If I can get the JB Weld off I may be able to re-use the retainer also. Most of the metal HW is okay (like all of the PerfectFlite nut/screw sets), one of the quick links and eye bolts was involved in the battery event, so it's pretty charred and I'm not sure I'd trust them at this point, the others were clear of the event and look fine. The Dog House charge wells are fine, my longer screws for it all need to be replaced. The terminal blocks don't look so good, but I'm going to replace them with a second set of charge wells. All my custom wiring from Dog House needs to be replaced. So as far as the Binder re-order went, it was the NC, fins/CRs, airframe/MMT, e-bay couplers/bulkplates, and one eye-bolt set. Basically all the plastic/wood/paper bits, hardly any metal, and no chutes/nylon. I can probably re-use the U-bolt if I can break through the Loc-Tite, and I have extra all-thread to replace that without needing more.

 

[woferry]

The replacement parts showed up Tuesday, for a brief moment I started thinking that I could throw the whole thing together to fly (naked) by Saturday, so I started off gluing the thrust plate to the MMT but then remembered that step #2 was beveling the fins which took some setup with my dremel "router" and a good bit of time, so I abandoned that thought about as quickly as it started. Next launch probably won't be until mid-May, so I have some time and won't be rushing things (though I am hoping to have another rocket built by then as well, that one is hung up on me figuring out how I'm going to bevel and route a groove into it's fins). So maybe Sunday I'll focus on the fins for both rockets.

But it's deja vu all over again with the parts sitting on my work table. Should at least be easier the second time around, or more like the 2.5th time since I also watched my dad build the fin can for his Excel (no DD). I did order the vent band 1" longer this time, the 4" band was a bit shorter than Landru13's Mobius camera shroud, and I decided I liked having it mounted there (watching the lower section separate at ejection looks pretty cool IMO) so having it fit properly would be better. Plus frankly the upper bay was a bit tight with my chute, protector and shock cord packed in, so I'll either put the full extra inch of the vent band towards the upper coupler to leave an extra inch in the upper bay, or split the distance and get an extra 1/2" in both bays but a 4.5" mate on both sides rather than 4" top and 5" bottom (or the default 5"/5").