Quantcast

Main reason for failing Cert flights?

The Rocketry Forum

Help Support The Rocketry Forum:

blackbrandt

That Darn College Student
Joined
Mar 18, 2012
Messages
9,281
Reaction score
40
Hey everyone,
Prepping for my L1 and L2 this weekend. I've been reading through threads trying to find the normal reason people fail their cert flights. Currently it looks like deployment is the biggest cause of failure. Any other points to watch out for? I'll have a very detailed checklist for each flight.
 

watermelonman

Well-Known Member
Joined
Sep 22, 2014
Messages
2,597
Reaction score
7
If you are a west coast university student the standard way to fail is to try to save money on hardware, wind up with a DMS H550, and shred your airframe on super thunder awesomeness. I have seen that one at least a dozen times now.

But seriously, definitely deployment. Another popular failure is trying to fly your L1 rocket with an L2 motor and losing it.
 

Ccolvin968

Well-Known Member
Joined
Oct 11, 2016
Messages
314
Reaction score
0
My short time in the HPR world and my L1 cert at the end of October taught me to be sure that you trim your delay appropriately.
It was pretty chilly, and I didn't shave enough out with the DAT because I couldn't feel my hands.
I passed despite the rocket falling 400ft from 846ft and a pretty energetic recovery.
Double and triple check everything.
I was nervous, but it all went well.
Clear skies and fair winds!
 

DavidMcCann

Well-Known Member
Joined
May 15, 2016
Messages
2,656
Reaction score
166
Recovery can be longer on cert flights than on smaller flights you've done

be sure to pack water, a phone, a map of the area, and some 5 minute epoxy ;)
 

djs

Well-Known Member
Joined
Jul 27, 2014
Messages
3,366
Reaction score
247
Saw several L1 fails this weekend- usually due to chute not deploying in some manner.
 

mpitfield

Moderator
Staff member
TRF Lifetime Supporter
Global Mod
Joined
Jul 7, 2013
Messages
4,900
Reaction score
430
Location
Toronto, Ontario
Big fan of doing check out flights, if you have a motor that will work in the rocket. Not doing this for my L1 caused me to have to repeat and had I done it I would have passed first round. When I went for my L2 I openly said I was going to do some "shake down flights". Quite a few people said why risk your rocket, however I would rather fail on a non-cert flight than a cert flight, and in this case the two pre-L2 flights proved to be invaluable. Not only did I have a recovery issue but I also identified a process issue in prepping. Had I not done the flights there is a very good chance I would have done a L1 repeat.
 

Buckeye

Well-Known Member
TRF Supporter
Joined
Sep 6, 2009
Messages
2,516
Reaction score
365
Simulate, ground test, shake down flights.
 

Nytrunner

Pop lugs, not drugs
Joined
Oct 15, 2016
Messages
7,190
Reaction score
2,667
Location
Huntsville AL
Putting as big a motor as is safe in the rocket when its wiser to fly something smaller (Eastern field = surrounded by forests).

Ground testing has been mentioned. And shakedown flights too. When I do my L2, I plan on doing both those.
 

mikec

Well-Known Member
Joined
May 9, 2009
Messages
2,443
Reaction score
348
Maybe overly ambitious cert flights. Lots of people are suggesting ground tests. Of what exactly? You can easily do an L1 and at many sites an L2 with a no-electronics motor ejection flight. If you've packed the chute in the rocket a few times previously on shakedown flights, do you really need a ground test?

In my experience many cert flights fail because of motor assembly errors. More common with AT RMS, but one can manage to mess up the assembly of a CTI or even an AT DMS motor.
 

rharshberger

Well-Known Member
Joined
Oct 13, 2014
Messages
9,708
Reaction score
1,692
Location
Pasco, WA
Maybe overly ambitious cert flights. Lots of people are suggesting ground tests. Of what exactly? You can easily do an L1 and at many sites an L2 with a no-electronics motor ejection flight. If you've packed the chute in the rocket a few times previously on shakedown flights, do you really need a ground test?

In my experience many cert flights fail because of motor assembly errors. More common with AT RMS, but one can manage to mess up the assembly of a CTI or even an AT DMS motor.
The answer to the "do you really need to ground test" is yes, not every airframe is identical and with RMS and CTI motors the provided ejection charge may not be enough. The ground test will determine if you need more or less ejection charge, a 38mm may need a reduced charge whereas a Loc Minni Mag 5.38" airframe may need a bit more. Having witnessed a fair number of Cert flights, recovery issues are more common than motor issues (most of the time), there was that issue at FITS where a bunch of CTI motors with bad forward closures CATO'd, and yes we also get the RMS CATO's but recovery is still the main reason for failure (now I just need to find that darn post where someone quoted the statistics).
 

DavidMcCann

Well-Known Member
Joined
May 15, 2016
Messages
2,656
Reaction score
166
Maybe overly ambitious cert flights. Lots of people are suggesting ground tests. Of what exactly?.
ejection if DD, which knowing BB i suspect.


Its also an inside joke referring to a poorly planned series of events at LDRS. ;)


Shakedown flights may prevent a cert failure.... but theres no penalty for a cert failure.... six or one half dozen to me.

ripped shock cords and bad delays are the biggest reasons for failure i've seen. I'll exclude fins popping, as you should be able keep those on
 

Rex R

LV2
Joined
Apr 21, 2010
Messages
6,101
Reaction score
142
according to the NAR the number one reason for all failures is recovery errors, I would imagine it is the same for Tripoli. I have seen a number of bad flights and cert attempts due to this. everything from delay issues (early and late) causing zippers, to separation problems. tangled chutes are about #3 on the list, motor failures are way down the list. so make sure your recovery harnesses are connected(nothing quite like seeing a nose cone get a very soft landing...). delays correct, and if going DD that you know how to arm the altimeter(s). good luck,
Rex
 

Forever_Metal

JustAnotherBAR
Joined
May 21, 2016
Messages
493
Reaction score
37
Location
Madison, AL
Biggest issue I've seen was not asking questions before showing up and trying to fly...

(as it was explained to me)
Find the local prefect or club, bring your machine and ask someone to check it out. There are plenty of L1/2/3 folks out there who if asked will spend a few moments with you to sanity check what you're doing... In fact, the local club may even have a mentor that will look over what you've done, and provide that extra bit of info or a fix to a particular problem.

IMO, for L1, try not to do much more than the basics... use motor ejection, build it tough, etc... Don't get bogged down in trying to do too much or to fly to the moon... Leave the electronics, dual-deploy, and high-altitude stuff for later. Learn the basic build, then fly, build another adding to the knowledge base, etc...

fm
 

MaxQ

Tripoli 2747
Joined
Jan 18, 2009
Messages
4,415
Reaction score
58
Location
Central Viginia - USA
Your own personal checklist at the field is a good thing.......there will be a lot of things going on and distractions.
I've seen some very (and I mean VERY) experienced flyers forget to hook up their recovery systems (have seen it on either end - amusing to see a nose cone under a big chute go cross country while the airfame comes in rather fast).
Happened last week as a matter of fact.

A solid recovery harness and hardware is a good thing.
Same for motor retention...both under acceleration and on ejection.
Battery tests on the field if you are using altimeters....particularly in cold weather.

Take your time.

Wasn't a cert flight, but I had an entertaining motor failure in a drag race, when I didn't listen for the click of a snap ring in the forward closure while assembling a motor in a bit of a hurry.
 
Last edited:

jeff2space

Well-Known Member
Joined
Nov 26, 2011
Messages
580
Reaction score
6
Location
Waterford, WI
My advice, concentrate on doing things the right way rather than being concerned about how things could go wrong.
 

AHansom

Well-Known Member
Joined
Jan 22, 2009
Messages
783
Reaction score
20
In my experience many cert flights fail because of motor assembly errors. More common with AT RMS,
That was me!!! The instructions are printed quite small and I put the ejection delay in backwards. Popped the nosecone at ignition and flew about 100' off the ground before cartwheeling with flames coming out of both ends.

sumo2.JPG
 

TopRamen

SA-5
Joined
Aug 9, 2013
Messages
9,955
Reaction score
83
Holy Crap! BB isn't L1 yet!

Man, you've been really into this stuff, and I always assumed you were like L2 by now.

I can't answer your question about what makes you fail at something, but I can tell you best of luck, and that I'm pretty sure you will get it right.
You seem like a pretty smart guy. I know you are into math and stuff.
 

TopRamen

SA-5
Joined
Aug 9, 2013
Messages
9,955
Reaction score
83
My advice, concentrate on doing things the right way rather than being concerned about how things could go wrong.
That's good sound advice.
In the Army, we just do it as we train to do it, not as we worry about it possibly happening.
Training, training, training and more training.
Muscle memory.
 

Dave A

Lifetime Supporter
TRF Lifetime Supporter
Joined
Jan 22, 2013
Messages
1,127
Reaction score
100
You can do Level 1 with the Pro38 H and Level 2 with the J. If you need a little more ump to deploy the chute in a larger rocket (& if it's allowed under TAP supervision) you can use a 1/2" slice of BT-20. It fits right in the Pro38 fwd with a little 5 min epoxy. Add a little extra powder and seal with tape. Again only if the Tap allows it.
 

DavidMcCann

Well-Known Member
Joined
May 15, 2016
Messages
2,656
Reaction score
166
we've all missed the obvious....

BB will fail because he sucks ;)
 

mpitfield

Moderator
Staff member
TRF Lifetime Supporter
Global Mod
Joined
Jul 7, 2013
Messages
4,900
Reaction score
430
Location
Toronto, Ontario
Shakedown flights may prevent a cert failure.... but theres no penalty for a cert failure.... six or one half dozen to me.
What are you talking about, you would have to fill out the paperwork twice.
 

boatgeek

Well-Known Member
Joined
Dec 27, 2014
Messages
2,923
Reaction score
1,350
Personally? L1 was a success after a shakedown that identified a weak recovery harness attachment. L2 was a failure--chute got stuck in the tube despite a prior successful flight. I don't think I've seen other failures besides the string of CATOs mentioned above that were due to manufacturer defect.
 

AlphaHybrids

Well-Known Member
Joined
Nov 29, 2009
Messages
1,566
Reaction score
77
I failed my L3 twice because I bent the aluminum fins on the fincan. Rocket landed in a rocky canyon - bad luck. Third time landed in a field, much better. Most disqualifications I've seen are recovery - up is the easy part. Zippers, chute not coming out when it is supposed to, tangled chute, etc.

Also, spend the $2 each and buy real e-matches. I saw a guy fail 4 L2 flights one year because he insisted on using Christmas tree bulbs. That gets expensive when you have to build 4 rockets because you were planting cardboard trees.

I saw on up and down because they forgot to turn on the altimeter. Ooops. Go Fever sets in sometimes.

Edward
 

UPscaler

New Member
Joined
Nov 25, 2009
Messages
4,240
Reaction score
137
I flew H-L before my certifications became an option and it STILL took me three tries to get my L1.

You are correct, deployment is namely the number one cause for a failed cert attempt...my second failure, though, was due to me forgetting to put my noseweight in in the midst of preparing for the flight itself. Did a cool loop and then plopped on the ground. Just stay relaxed and keep your composure, make sure you've got everything done and setup properly. You'll be fine.


Braden
 

fyrwrxz

latest photo
Joined
Jun 6, 2011
Messages
6,575
Reaction score
45
You got this, Matt! Get a good night's sleep and take your time prepping-don't let anybody interrupt you and go by your check list. Straight smoke and good chutes!
 

OverTheTop

Well-Known Member
TRF Supporter
Joined
Jul 10, 2007
Messages
4,375
Reaction score
1,605
Location
Melbourne Australia
As others' have said, deployment. Get someone who knows what they are doing to watch over your parachute packing. You will probably benefit from the experience (if you choose the right person!).
 

SpaceManMat

Space Nut
Joined
Dec 20, 2013
Messages
666
Reaction score
48
If you're doing a scratch make sure you understand the whole stability thing. Seen a guy fail 7 times because he did not have a good grasp on stability. Also seen a number of flights where they put the biggest motor in they could for a fairly soft airframe only to have a major disassembly event, I think QT is often associated with such flights.
 

terryg

Well-Known Member
Joined
Jan 19, 2009
Messages
2,514
Reaction score
51
Location
Tucson, Az
Biggest reason at our site recently has been failure to recover the rocket. A minimum diameter rocket at 5000 ft plus can get lost really quickly.
 
Top