Research! Your Help needed. Survey Recovery Failures

I would like to conduct an unscientific survey of recovery related failures. This should be fun and informative for all.

Ground rules:
1. Flights must be YOURS. Do not recount a failure you observed or heard about or was not your flight.
2. Only recount up to your last 3 failures (don't go back too far in time, stick to recent events in your memory).
3. A "Failure" is defined as any recovery event that didn't go as planned even if the recovery was safe and damage free.
4. Do not identify brands, keep equipment descriptions generic.
5. Do not "solve" or suggest solutions in this thread, keep thread pure and just describe and recount the failures.
6. If the cause was known, describe it. If the cause was not know just describe what happened. (Again no speculation on causes).

After a while I will summarize and Pareto the failures.

Have at it and thanks for helping.

Do not use a booster motor in a single stage rocket. Causes 'chute shred, tube zipper, broken shock cord and hard landings.

Mike

Hard to be vague and not include photos, but here we go.
My last three:

1) Reloadable motor ejection charge went off, nosecone failed to leave the BT. NC was loose fitting, 3" tube and maybe 6" of tube to pressurize. I have no idea how or why recovery failed. Result was a lawn dart 500 yards away from the pad.

2) 2.6" 2 foot tall rocket. Nomex burrito jammed on tube mounted paper shock cord mount. Result was a core sample

3) 2.6" 11 ounce Phoenix clone. E motor with a max thrust of approx 19N did not attain an altitude sufficient for the 6 second delay. Rocket weathercocked and lawn darted 200 yards from pad. Ejection charge blew after hitting the ground.

Last three, most recent to least recent.


1. 3" tailcone research rocket on an L motor. Intended to separate at apogee, descend drogueless, then release the main via a pair of redundant cable cutters. The separation went as planned, if a bit too energetic, but the main did not deploy. The burrito had jerked hard enough from the apogee event to rip the cable tie at apogee and rip the buttonhole in the nomex chute protector, which then slid down the shroud lines of the parachute. The causes: the charge was too powerful, and the parachute burrito filled the entire cross-section of the tube, so it jerked out of the rocket too fast. A narrower burrito would have allowed some venting around the sides, and also would have reduced the internal bursting force that ripped the cable tie. Make sure your burrito is bundled to the shock cord so it can't move around too much, and make sure the burrito is somewhat long and skinny. This was my first cable cutter flight with a relatively large and heavy (60") parachute, so I didn't know that these would be problems.

2. My L1 rocket on its 7th or 8th flight. I left the parachute in its bag in the rocket, so after the deployment event, it came down drogueless right next to the chute in its bag. Don't do this; always use a checklist!

3. Disappearing Act, a minimum-diameter minimum mass 38mm rocket on an I1299N, its 3rd flight. The rocket pulled a peak 220 G, so the metal tape BP charge actually got pulled off of the Q2G2 igniter, thus disabling the apogee separation. It lake-staked. Solution: If you have a flight with stupendous acceleration like that one, make sure that every component down to the finest details can withstand the downward "pull" of at least two times the necessary amount. I had prepared against the Q2G2 igniter pulling on the electrical connection, but the failure occurred at a different point than expected.

Last really memorable recovery failure:

3", ~4 lb cardboard tube rocket, 30" parachute - failed to fasten chute protector blanket to the shock cord or quick-link, and the button hole slid up the shroud lines, reefing the chute fully closed. Not terribly proud of that...

Mark
NAR/TRA L2
Central Illinois Aerospace

1. main shock cord broke. [old age]

2. forgot to fasten quick link of apogee cord [yep I'll admit it]

3.shockcord broke at apogee [ once again old age]

Only failures in over 100 last high power flights, I'll take that considering all my fault. Shockcords involved were over 7 yrs old & I was just lazy, pushing my luck. Did force inspection of all rockets & recovery gear.

Flew my "dim sun" with dual deploy a bit over a week ago. Drogue at apogee was perfect. Main came out at 1000' but didn't inflate properly. Rocket sustained minor cosmetic damage where the upper section smashed into the lower section. Otherwise no harm done.


-main chute packed too tight for too long... lesson learnt, don't leave a chute in the rocket for 2 months in ready-to-fly condition!

-parachute too far down shock cord and didn't come out

-very fast propellent failed to ignite the delay grain, thus no ejection took place

1. Not enuff 'ejection powder' in 4" bay-got the cone off but chute hung up; flat spin in. Pride damaged more than rocket
2. Engine not friction fitted tight enuff-came half way out, again cone came off-chute too tite in MD bird-flat spin in. meh-it's fibreglas. Same bird-energetic deploy-stuffed chute into hollow nose cone-frack! Re-rigged chute lower in recovery train and was successful.
3. Sorry but this had to be here. Piston hung up on motor eject and core sampled. No more pistons for me.

Dec 2012, Formula 98 on long burn K. Complete failure to deploy, either event, ballistic. I was able to solder wires where the terminal block had been. Altimeter never detected liftoff (and it was beeping correctly on the pad).
Sept 2012. Graduator on a G. Forgot to arm, ballistic.
June 2012. EZI on J500. Complete electronics failure, ballistic.
Of my crashes in 20 years of using altimeters, these 2 failures are the only ones definitely caused by failure of the electronics. This brand will never fly alone in one of my rockets again.

1) my qmodel Hawkeye, not enough ejection to push out the parachute, it flew spectacular to the ground to take a core sample and destroy it self.
2) my mega der red max, soon after motor burn out the nose cone was ejected along with the parachute, the nose cone hit one of the fins, no damage to the fins but the nose cone has two big cracks in it.
3) my Estes patriot, I put in a 24 mm motor tube and put it up on a Aertech E motor, the parachute shredded and came down like a streamer, I'm glad it did I would not have gotten it back but no damage.

1. low power rocket parawad. relatively rigid plastic parachute at approx 65F, was lightly dusted with talcum powder and packed, but I had other activities at the range before launching and did not repack. tailslide recovery clear of spectators with one fin snapped off and easily repaired.
2. mid power rocket lost parachute. moderate weathercock in strong wind and high-velocity deployment. non-locking snap swivel that I used a lot on low power rockets opened and the parachute escaped. rocket tumbled and loosened one fin on impact. now using quick links and barrel swivels for mid power and higher.
3. mid power rocket separation at deployment. kit design called for a paper bulkhead for payload bay. although covered with wood glue, a moderate velocity deployment with heavy (two eggs) payload caused the kevlar cord to rip through the paper bulkhead. nosecone and payload bay recovered in a flat spin with no damage. rest of rocket slowly returned under parachute. cut out remains of paper bulkhead and replaced with plywood bulkhead.

User Error #1 - Coupler was too tight to the airframe, not allowing the drogue seperation... nosecone was too tight to airframe not allowing the main to deploy... day was extremely humid and the phenolic airframe seemed to swell somewhat.. I flew the rocket anyway (suffering from go fever). Result: power core sample, total loss, all caught on video

User Error #2 - Packed a large chute into a small d-bag and attached too small of a drogue to the d-bag... main could not deploy from the bag. Result: everything recovered, very minor damage to rocket

User Error #3 - I hand tightened an eyebolt to the top bulkhead of a Sky Ripper Systems 38mm motor. Recovery deployed properly. The spin induced on the rocket by the fins on decent caused the eyebolt to spin out of the bulkhead very early after apogee... booster never recovered, main deployed and drifted the payload section many fields over. Result: booster and motor never recovered.

DRAGON64 said:

User Error #3 - I hand tightened an eyebolt to the top bulkhead of a Sky Ripper Systems 38mm motor. Recovery deployed properly. The spin induced on the rocket by the fins on decent caused the eyebolt to spin out of the bulkhead very early after apogee... booster never recovered, main deployed and drifted the payload section many fields over. Result: booster and motor never recovered.

Click to expand...

Exact same thing happened to me with the same motor except I recovered everything. After that Jam Nut and blue loctite all the time.

Last 3 recovery failures.

first reload ever... F40-4w No charge in BP well... Balistic re-entry, AIRFEST 14. (dont fly iwth the bp cannister in your pocket)
second (set of failures).
The alitmeter software puts a decimal point in the integer for alittude in main deploy. The program adds the decimal in the 10ths place if you dont do it. So when you set your main altitude 800', it stores the value as 80.0'.
the first flight i thought something just bound up. the second flight a nicely unfolded (but never inflated chute) was laying between the body and nosecone which was about 1' away. I now realize that the charge was firing 50' off the ground. now I use 500.0 and dont have problems.
Third failure.
(set of failures) altimeter reset at apogee. recovered under main the first time, failed to deploy main second time.
this problem is now fixed.....

all 3 crashes from failed main, was the same rocket.(different altimeters.)

1. Ejection charge burned, but nosecone didn't separate, resulting in lawn dart. Later investigation found a small hole in the motor tube apparently formed over many launches, that vented off the gasses.

2. Ejection charge burned and no separation, resulting in lawn dart. No explanation found, everyting was a nice smooth fit, and I put it down to slightly defficient charge size in that reload. I now add a small amount to supplement.

3. A 44" chute failed to open. I fold the lines into the chute and it normally works very well, but this time I had several inches extending from the folded and rolled chute. I was in a bit of a hurry and lightly wrapped those few inches around the chute. When I recovered the now damaged 4" rocket the single wrap of shroud lines was like a noose around the still folded chute. No chance of it ever opening.

1. April 14, 2013 Streamer ejected, but did not unfurl. One fin cracked on hard landing. Rocket has been repaired.

2. May 4, 2013 Parachute hanging only by one loop when rocket retrieved. I forgot to close the snap swivel after selecting the parachute. Rocket landed hard; one upper fin knocked loose and one lower fin broke in half. Rocket has been repaired.

3. May 25, 2013 I lost the nose from my Sidewinder rocket earlier this year. Cleaning up the basement I found the nose from my original Sidewinder kit from maybe 20 years ago and installed it on the newer rocket. I did not replace the cheap elastic shock cord and the elastic snapped on the very first flight with the replacement nose. I had no problem finding the nose cone.

These aren't by any means my most spectacular recovery failures, just my three most recent ones. Reverse chronological order:

1. Tiny scratch-built pen rocket launched on the appropriate tiny motor. Nominal flight but the shock cord broke at deployment due to insufficient heat protection and a poor choice of material for the cord. The very low mass rocket body tumbled harmlessly back to the ground. The (lightly) weighted nose cone descended safely on the still-attached streamer and both parts were promptly found a short distance from the launch area.

2. Scratch-built Level 1-class HPR launched on a large (G class) mid power reload. The reload was several years old. Delay was shortened per manufact. instructions using correct delay shortening tool, but the amount of delay reduction was simply guesstimated by yours truly at the field. Rocket did not achieve the anticipated altitude and exhibited weathercocking but otherwise had a safe vertical flight in a safe heading and trajectory. It achieved sufficient altitude but the flight was lower than anticipated with an excessively long delay after motor burn-out. Ejection occurred well after apogee. Chute did fully deploy and the rocket achieved a safe landing. The rocket sustained very short zipper damage (~ 1") to the lip of the main airframe tube at the separation point. The high speed deployment also caused the friction-fitted nose cone to separate from the payload section. The large balsa nose cone was subsequently found undamaged a short distance from the spot where the rocket landed.

3. Small lightweight sustainer of a standard multistage sport rocket was launched in an unsuccessful effort to achieve a qualified flight in a low-impulse motor class parachute duration event at a local club contest. The rocket was severely underpowered and it barely cleared the launch rod before falling back to the ground next to the pad. The motor finished thrusting before the rocket hit the ground and the rocket did not move after striking the ground. The deployment charge fired well after the rocket was already back on the ground. The rocket sustained one fin separation and another fin sustained a cracked bond at the root. The motor was not a recommended one for that rocket but had been chosen in order to satisfy the competition event requirements.

1) not really a 'failure' so to speak, but insufficient sealing of an av-bay bulkhead caused pressure spike which faked out a Raven altimeter and deployed main at apogee. I'm sad to say but this happened multiple times as we incorrectly identified the leak. Rocket was misplaced out of sight for unknown reasons before a successful test flight.
2) A rocket I consulted on failed at apogee due to airframe failure; the parts were jointed by a set of shear pins that, predictably in hindsight, sheared, causing the booster (and the included GoPro) to descend ballistic. Well clear of flight line, impressive smear where the gopro used to exist.
3) Parachute inversion on a motor-eject single-deploy sport rocket (Talon 2), cause unknown (but likely inept hurried chute folding by yours truly).


... 3.5, because it's interesting) Scratchbuilt 3'x72' 3FNC Dual Deploy USLI rocket in 2012; after successful ground testing and local flight testing, apogee charge in Alabama was severely underpowered and failed to separate. Fit of all components had been carefully inspected immediately prior to flight, charges fired but without separation, no changes in anything, etc. etc.. Suspected cause: black powder sifting combined with small charges. We carefully through repetitive testing selected the smallest BP charges which reliably separated the rocket and threw the pieces apart enough to let the shock cord go taught but no more. However, our tests, and the test flight, were done using BP from aerotech motors, in the little test tube containers, which we presume are representative samples of the particle distribution for FFFF BP. In alabama we flew with BP poured out of a 1-lb can that had been freshly opened; we suspect that due to considerable sifting and settling in the large can in storage, the powder on the top of the can had a skewed particle size distribution with larger than average grains, hence burned slower/less energetically, and was insufficient to shear the shear pins. Lessons: use a healthy amount of BP, and for very critical projects (like our Min Diameter N), re-mix your powder before pouring!

Apogee charge fired, main didn't. Ematch was intact. Tested afterwards with very high resistance. Altimeter had seen the match at launch, three beeps.

Ground tested main charge fired but failed to deploy chute. Rocket landed in perfect condition in a tree, tube broke when I cut the free down, lol.

Aggressive apogee charge caused inertial deployment of main chute. Failure per design.

1. 4" stubby on a 3 grain motor. Flight and Ejection perfect. Parachute was tangled in some loose thread off the parachute hem, came in flat a little too fast and landed on the road. Broke one of the fins. Root Cause Analysis: trim that loose thread!

2. Fiberglass 2.6 on a F motor. Delay was left way too long, chute popped about 20 feet from the ground. Core sample, paint scratches and the nose cone cracked. A sobering event even though it was far from spectators. Root Cause Analysis: Too small a motor for the weight of the rocket. Double check finished weight for sims.

3. RTF LPR with a 18mm C-5. Delay too long for weight of the RTF rocket. Nosed in. Root Cause: 3 second delay would be better.

1. bonus delay on reloadable motor - ejection charge went off after rocket already in ground - mostly destroyed rocket
2. bonus delay on reloadable motor - ejection charge went off just before rocket hit the ground - two fins broken off - re-epoxied and repaired easily ... same motor reload as #1. If I was going to add a 4th failure, it would be the same story. At first I thought it was me. Now I just am not getting that reload again.
3. 2 stage rocket, booster launched fine, however, rocket had turned horizontal when sustainer lit. Horizontal flight into field

#3: Shroud line on parachute broke. Hard landing cracked 1/8" unreinforced plywood fin. Outcome: rocket repaired, ready for next flight.
#2: Nylon strap shock cord melted through. Booster dropped from altitude, cracked 1/4" unreinforced plywood fin. Remainder recovered w/o incident. Outcome: rocket repaired, ready for next flight.
#1: Suspect weak ejection charge on commercial motor. Nosecone popped, parachute never made it to end of tube. Core Sample. Outcome: rocket is salvageable, however, it's been retired as an excuse (er... REASON) to build a bigger one).



Later!

--Coop

On a windy day, a highly overstable two-stager weathercocked enough that it had enough sideways momentum at apogee to rip 4/6 of the shroud lines from a typical low power plastic chute.

G powered rocket, roughly 2 pounds, chute got tangled in all the kevlar shock cord right at ejection. I must not have packed them carefully. Fell just fast enough to snap a fin.

Streamer not unrolling on a bt5. The tape that holds the streamer to it's mounting string is stiff enough and stays in it's rolled-up shape that it keeps the streamer held shut.

1. Custom BT20 14" body tube, 15" chute cut from a mylar ballon for parachute duration contest. Launched on a cold day, chute failed to open (was a ball of mylar streamer)

2. 36" BT55 with jelly beans as a payload on a D12-3 motor, and a too short kevlar shock cord. Tube zippered on deployment and some of the shroud lines ripped from the plastic chute (ripped plastic chute). Fin broke on landing. Used openrocket later to model the flight, it says chute deployed at 60 MPH.

3. Famous brand name red plastic chute failure on generic 3FNC with B6-4; shroud lines pulled off corners of parachute (chute tore). Broke fin on landing.

Bonus 4th because it's memorable: My 16th rocket launch years ago, was showing off my rocket to a friend's uncle who had launched rockets when he was a kid. I always stored the parachute out of the tube (just like Mr. Stine said to in the model rocket handbook!) but neglected my preflight checklist (in spite of Mr. Stine's recommendation in said manual) and hurriedly prep'd the rocket and launched it with no parachute.

jderimig said:

Exact same thing happened to me with the same motor except I recovered everything. After that Jam Nut and blue loctite all the time.

Click to expand...

I'm glad I was not the only one. I walked and walked and walked, and never found the booster... nobody was watching the full flight, so the seperation was never spotted. My excuse; sun got in the way...but definitely user error to be gin with.

My last failure was with RC controlled chute in my 4" rocket. I was using the "trainer" switch instead of the Channel 5 switch on the radio and the RC charge didn't fire when I tried it after drogue deployment. When I figured out what i was doing and got the RC charge to fire, I think the RC charge and the altimeter charge both when off at the same time. The chute came out of the d-bag, but tangled badly, never opened, and the rocket fell fast. The upper payload tube (LOC tube with two layers of 6 oz glass) was zippered 12".

The previous flight with the RC controlled chute was also a failure. The RC controlled charge went off correctly and the chute deployed (no d-bag on this flight), but the shock cord on the nosecone wrapped across the top of the chute, causing that side to collapse and the chute to spin. I had no RC control of the chute. It still came down much slower then if it had fallen with the drogue only so there was no damage.

Launched a 3" DD rocket on a J350W to 4407 ft. Both e-matches were measured for resistance before the flight. Both were between 0.8 and 1.2 ohms. Neither match fired. Amazingly, the rocket fell flat the whole way down and landed behind a hill and about 100 yds into a field of standing corn. There was no damage. Both matches showed "open" when measured for resistance after the flight and the altimeter was beeping out the altitude just like a nominal flight. Both matches were commercial matches and each was from a different manufacturer that I've used before. I chalk the falling flat and walking right up to it in the standing corn that was hidden behind a hill, to incredibly good luck and the failure of both matches to incredibly bad luck.

Mine are fairly minor but they have a common thread (literally).

1. The glued in shock cord mount designed for elastic undie strap let go dropping my little 3" rocket like a stone. I learned that method doesn't work with no stretch kevlar.

2. Too long of a delay and too small diameter kevlar shock cord rips the crap out of a paper 4" tube.

1. Delay grain was approximately 5 seconds longer than anticipated. Resulted in a torn main chute in post apogee event. Rocket landed fast but no damage.

2. Lawn dart from 1500' apogee. Electronics in nosecone controlling deployment were destroyed - cause of failure unknown. Filament wound airframe and aft fin section undamaged. Was able to rebuild nosecone and fly again.

My last three were all with the same rocket, and all for a similar reason.

performance 1/4 patriot:

Failure one and two were from not enough BP in a stock CTI 38mm reload, nose cone separated, but the chute never made it out of the tube. The rocket core sampled both times; the first time it hit soft earth, the second it hit rocks. Repairs followed.

The most recent failure was after I converted the rocket to dual deploy, I forgot my smaller chute at home, so I reefed a larger one, but it was packed too tightly. The apogee event fired (along with a full delay motor eject backup) but the main charge didn't get the chute out. The rocket flat spun into the ground.