Complete failure. No clue what happened.

NateLowrie said:

Sorry I am late to the mourning and analysis. I liked that radial flyer too. I have another theory. Did you use shear pins on the drogue bay? If so, were the holes loose or tight when you inserted the shear pin? If the holes got bigger over time, I would bet that what happened was the pin(s) deformed instead of shearing clean off. That can happen when the holes are not tight and the deformation ends up taking a lot more total energy to break. I would bet at least one of the 3 charges fired and it wasn't enough to break the pins.

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Nope. My holes are threaded and I still had to screw them in. Good idea, though.

And thanks to everyone who has expressed sympathy. I know we've all been there.

Bat-mite said:

Nope. My holes are threaded and I still had to screw them in. Good idea, though.

And thanks to everyone who has expressed sympathy. I know we've all been there.

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You have my sympathy too. I think if you fly for any length of time you will lose a rocket or get damage due to unexplained circumstances. I lost one this weekend also, on its second flight when the apogee charge didn't fire. The terminal velocity on most rockets is about 300 mph. The main deployed at 300 ft and opened above the ground. No damage to the chute or on the upper section but I would guess the fin can was doing +150 mph when it hit the ground. The ground won.

I lost this one due to temperature change. The nose cone was appropriately tight at home, but too tight on the field. I hurriedly sanded the nose cone shoulder but not enough, it had been my best paint job to date.





I hope you figure it out.

FWIW, I did the same failure on my Wildman Vindicator. I re-kitted it twice - shattered every glue joint, but all parts were ok. The 2nd time the coupler hung on the apogee charge (definitely fired) and the main was at high speed and tore every shroud line off like you described.

The shear pins broke, but it got torqued to the side and never fully separated. I think I had to snug up the fit with some masking tape so it couldn't wobble to fix the issue.

Bummer about your rocket. FWIW, here's the pdf of an altimeter trace from a dual deployment flight with a stuck coupler. The first pressure spike is the drogue deployment charge. The second is the motor backup...stuck coupler. The final spike is the nose cone and parachute deployment at 170 mph. I rebuilt the core sampled booster only to lose it for good when I flew one of the CTI 38mm motors with the defective forward closure...
Don

View attachment Black Brant failed dual deploy 11-22-14 H225 WT.pdf

Nice parabolic flight. Bummer. Kurt

Wow, that was a great looking rocket, a real bummer to lose it.

Did you prep the rocket at the field in the cold or was already assembled before it sat in the cold? When I first started in HPR (right about 2001) my first kit was a PML kit with Quantum tube. I read how cold could affect it but just blew it off since I am in Texas. Of course we had a launch when the temp was about 40 degrees and I could not get the piston (remember those?) to budge. The coupler would also not fit into the body tube.

Of course I realize that your rocket wasn't plastic Quantum tubing but the only thing that makes sense is a stuck coupler. And the cold temps could definitely have been a factor in that. If you buttoned it all up at the field after it had equalized to ambient temps and it was fine then likely not the case. But if it was put together beforehand it becomes a stronger candidate. We all know that BP residue builds up over time and can cause binding, add extra friction from a contracting body tube and that makes a reasonable explanation. Your prior flight is an independent event and does inform much as to this flight.

No way to know for sure but cold temps have caused a lot of crashes, from bad batteries, to too much friction, and worst of all, o-ring blow by.

Sorry for the loss of your rocket, always hurts to lose a milestone bird.


Tony

John,

I'm sorry to hear about your Radial Flyer. I hope this info. helps. When the initial testing was done with the canvas we took equal lengths of airframe and coupler and put one in the freezer and one in the oven to 180 degrees. We then reversed which piece was heated and which cooled. We also soaked the same pieces in a bucket of water for 24hrs. In all cases the fit between the coupler and airframe were not affected by any noticeable amount. I have included the physical and thermal properties for the Canvas.

Physical and Thermal Properties
Thermal endurance index @ 20,000 hrs 6.0 IEC 216 - 248°F T.I.
Density 7.2 IEC 1183-A All 1 .722 oz/in3
Water Absorption 7.1 IEC 62-1 4 6.9-6 oz/in2
Conditioning: 1: 24h @ 73°F & 50%RH
2: 24h @ 73°F & 50%RH + 1hr in oil at 194°F
3: 96h @ 221°F + 1hr @ 73°F & 20%RH
4: 24h @ 122°F + 24hr in water at 73°F
5: 96h @ 221°F + 1hr in oil at 194°F

Thanks, Mike. How about the wood bulkheads? If the coupler hung up, maybe the wood swelled? I don't know. I'll probably never figure this out.

Oh, BTW, I did check the motor and the motor charge did blow. So we have to coupler with stuck coupler. How and why is probably something I'll just never know.

I keep coming back to the fact the Scorpion with one charge deployed (and at a slightly colder temp, too), whereas the RF with three charges did not. And never had any problems before. Is what it is, I guess.

Heck, maybe somebody glue my coupler in as a joke while I was in the loo. :grin:

I'm not sure what your typical setup is, but My dual deploy rockets usually have shear pins for the booster-to-payload connection, metal screws to hold the payload together with the forward airframe, and shear pins for the nosecone. Is it possible you put screws in the lower portion and nylon in the upper? That would cause the drogue to not deploy.

Normal setup for me


Reversed setup preventing drogue deployment.


I've almost done that before, but caught it right away.

Bat-mite said:

Heck, maybe somebody glue my coupler in as a joke while I was in the loo. :grin:

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I WASN'T THERE! :grin: Seriously, my condolences on the stuck coupler and destroyed rocket.

Mark, no chance. I use plastic rivets to hold the coupler to the payload tube, and they are 1/4" vs. #2 shear pin holes. :wink:

boatgeek said:

I WASN'T THERE! :grin: Seriously, my condolences on the stuck coupler and destroyed rocket.

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Ah, so it was you! Of course you would say you weren't there .... :neener:

Sorry about the rocket. I don't have any advice, just noting that I have my own similar failure analysis to do, though I have more to inspect when I finally get around to it.

My Excel w/DD that was my L2 cert rocket had a minor crash the last time I flew it. Fully-redundant altimeters (one SLCF and one EasyMini), separate batteries, matches and charge wells. Both altimeters fired their apogee charge just fine, neither one fired the main charge. So I saw that it landed drogue-only, when I got to the rocket I found that the upper airframe had partly unraveled at the spiral seams, so I initially concluded that the main charge(s) had ruptured the tube (it had a few hard landings earlier on so I knew the tube was probably weakened, and the main has always been a fairly tight pack). But once I got it home and took it apart there were both main charge wells, still covered with electrical tape. So somehow both altimeters (even though both were beeping as they should on landing) had failed to fire their charges. When I reviewed the video the airframe was clearly intact until it hit the ground, then it tore.

I use MJG Firewire initiators, but I trust this box as it was my replacement box for an initial bad-batch, and every other match in the box (I'm like 2/3 of the way through the box of 80) has fired just fine. So I'd have to have been incredibly unlucky for the first two bad matches out of like 50+ both went into the same deployment side of the same rocket. Yet it would be equally odd that both altimeters/batteries/etc failed at the same time, so this one has me stumped so far. But I haven't done anything with the charge wells since the flight (including removing the BP), so I haven't checked to measure their resistance or see if I could fire them after the fact, etc.

How high was this flight? Igniting BP is a known problem at higher altitudes. Effectively, if you don't pack it in a long tube, then only the bottom bit lights and the rest of the BP gets blown out without igniting and failing to generate the required separation pressure. This problem might be exacerbated by the cold and could possibly explain why all three charges failed to separate the rocket.

The stuck coupler theory makes the most sense. One issue I ran into early on was catching a loop of recovery harness in between the coupler and body tube. As is slid the coupler down I think the Kevlar rolled up and got thicker. It got pretty tight at the end. I didn't think much about it until I had to pull it apart because I did not fly the rocket. As I pulled it apart the now much thicker cord caused the coupler to bind on one side. I had to rotate it back and forth to get it off.

A compounding issue may be your charge sizes. How much margin did you have on your charges? If the charages were a bit light that would add to the theory of a stuck coupler and not enough power to overcome it.


Tony

Ahh, stuck coupler, bummer. It should be a rule your L3 rocket always flies good. If only it was that easy....

how much pressure do you aim for with your ejection charges?

Are you currently working on a replacement for LDRS?

John,
I'm really sorry man.
I hadn't seen this before..
I know that rocket was really important to you..
I know how cold it was on that day, ( that's why I didn't go, lol )..
Was the lower half assembled before you got to the field ??
I'm going with some moister / condensation / humidity in the lower that froze when you got to the field..

You said one of the harnesses was damaged,, that's unusual..
Send me the harness back,,
I'd like to see it.. I'll fix it for you..
Do you have my shipping address ??

Teddy

I think there is enough info here that you know what happened, maybe not exactly how. So where to go from here?

Not trying to throw gas on the fire here John, your a smart guy and I know you tested like crazy, I remember following your entire L3 build. But others can learn from all of our mishaps.

Not saying you do this but I continually see people test Ejection charges here on this forum 1.0 gram then that doesn't work, 1.1 he no
Love, 1.2 - hey that worked so I'll but a little extra 1.3 gram in there. That is pissing in a bathtub. Unless this is a small rocket (2.5" and below) I've been told to work in increments of .5 gram only and your backup needs to be a significant increase from your primary. On my L3 rocket I had to hone both AV connections because it would
Slide in fine but had to work on getting it out. After a significant hone - it felt so smooth and still had a good fit- so I tested at 4.5 and 5 - both separated. However in talking to my TAP and others that had much experience with the same rocket " blow it out or blow it *** jokingly kept coming up. Then a friend said he had a 6 gram charge not separate the payload and his 7 gr backup did the trick - so he now is at 7 primary and 8 backup - with a long harness and 15-20 flights on the rocket. Of course this is FG and non piston long harness setup. I took his advice on my L3 even though I tested at lower charges. That laundry has got to come out in our hobby, too dangerous otherwise.

Big Charges: So I went a little higher on my phenolic and cardboard rocket - not a long enough harness - this stressed the NC bulk head and on my phenolic it split the end of my booster tube. So in conclusion just increasing your charge without planning for it is not the best option based on my experience. So IMO the important factors of using strong charges are; The type of tubing material can withstand, relief holes, smooth connection even if you have to hone and long harness.

There is nothing worse than watching a rocket come down ballistic and knowing everything is armed but obviously will happen to all of us and we hope and pray no one is in the area. "What the freak just happened??!" Aww crap (or other expletives). Heck if I lost my L3 I'd probably walk away for awhile as I know I've got $2600 and 4 months wrapped up in it (of course many on the forum have much more $ and time wrapped up in theirs). CJ might chime in here, when I was crying about my ballistic L1 rocket from a stuck coupler he wrote me a little story about an experience he had at black rock with a very expensive rocket didn't make mine hurt as bad. At LDRS 34 man I saw some big CATOS and thought oh man these guys and gals got to be sick! No matter how expensive they all hurt.

One way to get over it is to enjoy building another monster on the rebound . I look forward to following that build thread.

This definitely has me rethinking my procedures for colder launch days... I am thinking an an extra step at the field to remove the shear pins, back the coupler out halfway and reseat it after it's been in ambient temps for 30+ min. That step will let you know very quickly if there are any issues with fit in the cold.

What was the apogee of both flights? A higher altitude on a cold day means a really cold environment at deployment. 5000 feet can easily be 20 degrees colder. Perhaps a clue in air temp differences? Different contraction rates of materials?
Just another variable to consider

spence said:

What was the apogee of both flights? A higher altitude on a cold day means a really cold environment at deployment. 5000 feet can easily be 20 degrees colder. Perhaps a clue in air temp differences? Different contraction rates of materials?
Just another variable to consider

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That's as likely as anything. Definitely went more than a mile up, although I don't see how wood and canvas phenolic could just suddenly contract for the few seconds it was up that high.

Bat-mite said:

That's as likely as anything. Definitely went more than a mile up, although I don't see how wood and canvas phenolic could just suddenly contract for the few seconds it was up that high.

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I'm not a wood/canvas/phenolic guy, but I doubt this was the issue.

Did you call your altimeters bad names recently? Speak ill of them in their presence? Maybe they just decided to rise up and go on strike?

djs said:

I'm not a wood/canvas/phenolic guy, but I doubt this was the issue.

Did you call your altimeters bad names recently? Speak ill of them in their presence? Maybe they just decided to rise up and go on strike?

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Yes, I am a brute! :grin: But even if I did, I still don't know why the motor charge didn't get it out. Had to be a stuck coupler, but why -- all of a sudden -- unlike any other launch -- it stuck, is the mystery. Three charges, no separation. No data. No answers....

Bat-mite said:

Yes, I am a brute! :grin: But even if I did, I still don't know why the motor charge didn't get it out.

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Motors are members of the Teamsters- sympathy strike. Next it'll be your ignitors, and then the parachutes.

my vote is still for stuck coupler as well. Time to build another one!