Certing Level 2 tomorrow with a CTI K675 Skidmark!! WOOOOOOOOO!!!!

The Rocketry Forum

Help Support The Rocketry Forum:

OhioFlyer

Well-Known Member
TRF Supporter
Joined
Jun 4, 2021
Messages
48
Reaction score
12
Sorry to hear it. Were you able to recover video from the onboard cam? Any good video from the ground?
 

Mach_Seven

Well-Known Member
TRF Supporter
Joined
Jan 30, 2021
Messages
528
Reaction score
486
Sorry to hear it. Were you able to recover video from the onboard cam? Any good video from the ground?
I just posted the YouTube link here in the thread. The on board didn’t record for some reason. I 100% confirmed the camera was recording before we launch. No files recorded though.
 

OhioFlyer

Well-Known Member
TRF Supporter
Joined
Jun 4, 2021
Messages
48
Reaction score
12
Wow, I know you said it took a hard right but I was not expecting a 90 degree turn. Hurts to see it.
 

Mach_Seven

Well-Known Member
TRF Supporter
Joined
Jan 30, 2021
Messages
528
Reaction score
486
I agree with your conclusion, regardless of the sequence of the events that caused it, the airframe failed. I also failed my first attempt for L2, due to a singed piece of tubular nylon that separated when the main chute deployed.
Each level we attain makes us come to terms with the forces we are dealing with, not only with the motors we fly, but also with mass and momentum during recovery.
I thought I had a pretty good handle on everything when I got my L3, but I later flew a 6" Ultimate Darkstar on an O3400 Imax and got another lesson. Both rail buttons were gone, and the Stickershock decal that I had coated with a generous clear coat had all the leading edges peeled back. o_O
Never quit learning, it will keep you young, even at 70.
Thanks for the input. This one will sting a while, but I'll be back.
 

KenECoyote

Well-Known Member
TRF Supporter
Joined
Mar 19, 2015
Messages
3,148
Reaction score
428
Please don't take this as criticism nor an attempt to kick you when you're down...

When I first read your post, I thought that Mach 1+ on an L2 attempt with a custom modded rocket may be a bit ambitious and I'm one that likes hard challenges. :p

However every mistake we make is valuable in the learnings and experience we gain from them. Do take on the challenge to not let this discourage you and try again! (Maybe with a milder motor. ;) )
Also given the workmanship and coolness of this attempt, I'm sure we'll be seeing more of your rockets here. :)
 
Last edited:

Sooner Boomer

Well-Known Member
Joined
Mar 21, 2011
Messages
3,955
Reaction score
1,810
Really sorry to see the results of the flight. That looked like a beautiful rocket. You got all your hardware back, didn't you?
 

SkyFire

Well-Known Member
Joined
Oct 20, 2020
Messages
2,330
Reaction score
6,689
Location
Tucson, AZ
Cool rocket! Sorry it came apart on you.
The model rocket industry thanks you for re-kitting your rocket in order to provide them more capital.
 

RocketScientistAustralia

Lifetime Supporter
TRF Lifetime Supporter
Joined
Jun 30, 2015
Messages
212
Reaction score
181
Location
Australia
Make your cert flight as simple as possible. Then do the fun stuff. No need to document what went wrong then.
In your design would you place 140 lbs of load on the top of your cardboard tube? The launch thrust spike will be higher. That’s your thrust and it gets transmitted through your tube.
Norm
 
Last edited:

Five

Well-Known Member
Joined
Jun 10, 2020
Messages
431
Reaction score
297
Where the video. I’m always down to watch an on board camera?
 

Sandy H.

Lifetime Supporter
TRF Lifetime Supporter
Joined
Mar 20, 2009
Messages
1,055
Reaction score
469
I live on the east coast, so 'low and slow' is very common to hear around here. Sure, fly the field, but the OP had a good field to fly so 'low and slow' isn't required.

Sure, he built a good rocket, flew it with a hard hitting motor and might have gotten into fin flutter and the particular flight was less successful than originally intended. I've seen plenty of 'seasoned' fliers at their level do similar. If the RSO/LCO were good with the flight (and it did look like a solid build for sure) if the OP wanted to fly that as their L2 flight, I think they should do it every time. 'Low and slow' is 'safe and logical' if there are hard goals to achieve. But if your next flight is going to be a hard hitting motor, IMO there is no difference.

Sorry to hear about your result, but I imagine you attempted a flight profile you wanted to try and whether you flew a 10" diameter on a J350 to get your L2 first vs. flying the flight you wanted to fly, all you did was to get to the outcome without wasting your money on building and storing a 10" rocket and the cost of a J350. . .

I think 'fly the field' is a much better mentality that 'low and slow' for certs. Fly what you want, but always fly the field. If you're worried, ask for help from the more seasoned fliers, of course. I'd say your first L2 flight was somewhat aggressive, so hopefully the RSO/LCO or other members of the club can help for future attempts that are similar for future fliers. But if someone wants to do something similar on a cert attempt, just take the lessons learned and let them fly the flight, if it passes the RCO/LCO table.

I look forward to your rebuild and to learn what you do to address the anomaly that happened.

Sandy.
 

Steve Shannon

Well-Known Member
TRF Supporter
Joined
Jul 23, 2011
Messages
7,221
Reaction score
4,400
Location
Butte, Montana
Did you recover the parachute? Did it rip off and float away (I thought I heard you discussing it on video.)
I’ve seen rockets take a sharp tun like that before when the chute comes out during thrust. Usually it either rips the chute off or blows panels out. That would be like a “flying w” on the rocket, causing zippers, and/or folding the airframe.
Obviously I wasn’t there and can’t say for sure that’s what happened. Was the nosecone shear pinned?
 

Mach_Seven

Well-Known Member
TRF Supporter
Joined
Jan 30, 2021
Messages
528
Reaction score
486
Please don't take this as criticism nor an attempt to kick you when you're down...

When I first read your post, I thought that Mach 1+ on an L2 attempt with a custom modded rocket may be a bit ambitious and I'm one that likes hard challenges. :p

However every mistake we make is valuable in the learnings and experience we gain from them. Do take on the challenge to not let this discourage you and try again! (Maybe with a milder motor. ;) )
Also given the workmanship and coolness of this attempt, I'm sure we'll be seeing more of your rockets here. :)
I wouldn't post in these forums if I didn't have thick skin or couldn't handle some hard truths! lol I truly believed this rocket could handle the impulse. My thinking was, "If I don't intend to fly J motors, why cert with one?" If I fail my Cert attempt, than I am not ready for these big motors yet. My pride hates me for saying that, but the simple truth of the matter is this: ROCKETRY IS HARD!

I still think the Open Rocket sim of 19 G's was off somehow. Looked more like 30. It was doing 600 mph and still accelerating less than three seconds into flight.
 
Last edited:

Mach_Seven

Well-Known Member
TRF Supporter
Joined
Jan 30, 2021
Messages
528
Reaction score
486
I live on the east coast, so 'low and slow' is very common to hear around here. Sure, fly the field, but the OP had a good field to fly so 'low and slow' isn't required.

Sure, he built a good rocket, flew it with a hard hitting motor and might have gotten into fin flutter and the particular flight was less successful than originally intended. I've seen plenty of 'seasoned' fliers at their level do similar. If the RSO/LCO were good with the flight (and it did look like a solid build for sure) if the OP wanted to fly that as their L2 flight, I think they should do it every time. 'Low and slow' is 'safe and logical' if there are hard goals to achieve. But if your next flight is going to be a hard hitting motor, IMO there is no difference.

Sorry to hear about your result, but I imagine you attempted a flight profile you wanted to try and whether you flew a 10" diameter on a J350 to get your L2 first vs. flying the flight you wanted to fly, all you did was to get to the outcome without wasting your money on building and storing a 10" rocket and the cost of a J350. . .

I think 'fly the field' is a much better mentality that 'low and slow' for certs. Fly what you want, but always fly the field. If you're worried, ask for help from the more seasoned fliers, of course. I'd say your first L2 flight was somewhat aggressive, so hopefully the RSO/LCO or other members of the club can help for future attempts that are similar for future fliers. But if someone wants to do something similar on a cert attempt, just take the lessons learned and let them fly the flight, if it passes the RCO/LCO table.

I look forward to your rebuild and to learn what you do to address the anomaly that happened.

Sandy.
Well, gee. Pretty much this. You've nailed exactly what I was thinking. Thanks for saving me the trouble of having to write it out!
 

downhill_D

Well-Known Member
Joined
Jul 7, 2018
Messages
323
Reaction score
103
Oh man. That's a very difficult day, sorry it did not work out. Most of us here know the amount of time spent on one of these is a great dedication of our time. Your next build will be better.

My last J flight lawn darted and I lost everything (electronics, chutes melted from impact/friction etc.) so I hope your electronics survived. As you probably know, the data is very valuable in solving what happened. Was your addition to the booster section (your specs say you added 12") connected with a regular LOC coupler or a "Stiffy" coupler as well? I noticed you had modified the booster section and had heard some "K's" can fold in regular couplers so I now overbuild my connections and foam my fin cans.
 

Mach_Seven

Well-Known Member
TRF Supporter
Joined
Jan 30, 2021
Messages
528
Reaction score
486
Did you recover the parachute? Did it rip off and float away (I thought I heard you discussing it on video.)
I’ve seen rockets take a sharp tun like that before when the chute comes out during thrust. Usually it either rips the chute off or blows panels out. That would be like a “flying w” on the rocket, causing zippers, and/or folding the airframe.
Obviously I wasn’t there and can’t say for sure that’s what happened. Was the nosecone shear pinned?
The parachute separated completely when the 1" nylon strap snapped right in the middle. So I had a 52" chute in full bloom carrying nothing but a piece of shock cord and my JLCR about three counties south. I overheard my friend with the binoculars who was tracking it (for several minutes) say, "Karl's never gonna find that." He was right. "I'm like "Did you see it go behind the tree line?" "No, it went over the horizon."

The nosecone was screwed to the payload and avionics bay, which was still shear-pinned to the lower airframe.
 
Last edited:

Mach_Seven

Well-Known Member
TRF Supporter
Joined
Jan 30, 2021
Messages
528
Reaction score
486
Oh man. That's a very difficult day, sorry it did not work out. Most of us here know the amount of time spent on one of these is a great dedication of our time. Your next build will be better.

My last J flight lawn darted and I lost everything (electronics, chutes melted from impact/friction etc.) so I hope your electronics survived. As you probably know, the data is very valuable in solving what happened. Was your addition to the booster section (your specs say you added 12") connected with a regular LOC coupler or a "Stiffy" coupler as well? I noticed you had modified the booster section and had heard some "K's" can fold in regular couplers so I now overbuild my connections and foam my fin cans.
I think you may have just solved the mystery even further. I know she folded over, but never considered the joint in the airframe being the weak point. Looking at where the kink is (using the decals as a guide), that's right about where the failure occured.
 

Mach_Seven

Well-Known Member
TRF Supporter
Joined
Jan 30, 2021
Messages
528
Reaction score
486
Make your cert flight as simple as possible. Then do the fun stuff. No need to document what went wrong then.
In your design would you place 140 lbs of load on the top of your cardboard tube? The launch thrust spike will be higher. That’s your thrust and it gets transmitted through your tube.
Norm
Oh, my pleasure! I think I'm personally funding the retirement of Jason at LOC Precision...
 

downhill_D

Well-Known Member
Joined
Jul 7, 2018
Messages
323
Reaction score
103
:/ Well shoot. I noticed the change in your specs and saw the decal location of the fold...dang. I don't like to be right about someones mishap. If you go the route of the extra couplers...I bevel the ends of the thicker coupler now and glue to the regular coupler outside of the airframe first! :rolleyes: The "stiffy" couplers are bulky (like .25" thick) inside the airframe and the thicker coupler could potentially catch harness connectors etc. Best of luck on a quick rebuild! If you have enough parts left the rebuild could be cheap too! I cut new fins, motor rings and ordered slotted tubes, couplers and an av bay kit to save money instead of ordering a whole new kit. (hyperloc 835)
 

FredA

Well-Known Member
Joined
Jan 19, 2009
Messages
2,359
Reaction score
511
My guess is the cardboard folded in the direction of that huge camera shroud.
It represents quite a large, asymmetrical load.
 

Mach_Seven

Well-Known Member
TRF Supporter
Joined
Jan 30, 2021
Messages
528
Reaction score
486
My guess is the cardboard folded in the direction of that huge camera shroud.
It represents quite a large, asymmetrical load.
It was, in fact, on that same side. Probably more of an "aggravating factor" than the primary cause of what seems to be an airframe joint failure.
 

SkyFire

Well-Known Member
Joined
Oct 20, 2020
Messages
2,330
Reaction score
6,689
Location
Tucson, AZ
For high power rockets I don't do the cardboard tube variety and only build fiberglass ones.
- Stronger, more durable
- No filling and sanding of spirals
- Less chance of zippers
- Better suited for high impulse motors

But, hey, that's me.
Different strokes for different folks.
 

Banzai88

Lvl 1,Wallet....Destroyed
TRF Supporter
Joined
Jul 15, 2015
Messages
2,859
Reaction score
1,054
For high power rockets I don't do the cardboard tube variety and only build fiberglass ones.
- Stronger, more durable
- No filling and sanding of spirals
- Less chance of zippers
- Better suited for high impulse motors

But, hey, that's me.
Different strokes for different folks.
I wonder how all them folks did all those L2 and L3 certs and flights before all fiberglass rockets became a 'thing'? 🤪
 

Steve Shannon

Well-Known Member
TRF Supporter
Joined
Jul 23, 2011
Messages
7,221
Reaction score
4,400
Location
Butte, Montana
I wonder how all them folks did all those L2 and L3 certs and flights before all fiberglass rockets became a 'thing'? 🤪
Exactly. It's a little like walking uphill both ways to school, but we flew a lot of cardboard rockets. We filled spirals. We added stiffies to couplers. We glassed phenolic airframes.
It's easy to buy a fiberglass kit, put it together and certify without knowing any of the "old school" skills. Should we hold that against those who are learning the hobby today? Is there some skillset that we should require to be used before we certify someone?
I guess it's like comparing people driving from St. Louis, Missouri to Sacramento, California to those who had to know how to drive a team, shoot game to survive, and fix wagons. Some skills simply become obsolete, like setting points in a distributor. So, no, I don't think we should make them go through what we had to do in order to succeed, but it would be nice if those who brag about doing things easier appreciated us old farts.
I appreciate the fact that Mach_Seven tried this using a LOC rocket instead of doing it the easy way. That he glassed the fins and doubled up on some things is great. Yeah, he may have found the speed of cardboard, but he learned a lot.
 
Last edited:

3stoogesrocketry

Well-Known Member
Joined
Feb 26, 2012
Messages
1,569
Reaction score
360
What size vent holes did you use? I shredded a mach 2 attempt because of inadequate ventilation in the main bay .
 

Mach_Seven

Well-Known Member
TRF Supporter
Joined
Jan 30, 2021
Messages
528
Reaction score
486
What size vent holes did you use? I shredded a mach 2 attempt because of inadequate ventilation in the main bay .
There were three 3/16” holes in the booster, one in the switch band, and one in the payload bay. There were also two 1/4” holes in both av bay bulkheads. The failure occurred at 1800 feet. Is that enough of a pressure change to burst the airframe do you think if it wasn’t vented?
 
Top