My L2 Project...

On August 24th, 2002, I launched my L2 rocket... and the Pro38 J failed... damaging the rocket.... Here is the story:


https://www.gardei.com/MegaBlast/MegaBlast.html

Take Care,

Doug

Doug,

Fantastic story!!! Well written and made me WANT to keep on a goin'...sorry to hear about the Cato...I have had a 4 grain Pro38 do the same, so I know the kind of power coming from that case as it passes through the upper BT. I does sound like you were well prepared and it also sounds like repairs are underway, so definitely keep us posted man!!!

Once again, Thanks for a great story, and Welcome to The Rocketry Forum!

Carl

BTW...I remember where Derry NH is...I used to live in Salem, NH...Lotsa BIG trees!

Doug,
My dad did his level two with a highly modified PE Bullpup. The first "flight" was a J350 CATO. Luckily, the forward closure held and the aft blew, pushing the rocket about ten feet. The casing expanded so much in the motor mount that it had to driven out with steel piping and a sledge hammer!!! The rocket had no damage from the CATO, only the landing after the fall. We can definately relate to your experience, but do as we did and rebuild and try again!!! Have fun too!!!

Here is a picture of the second, and successful flight of the Bullpup on a J350.

Doug,

Major bummer man.
I have had my share of PRO38 catos, but Anthony at CTI has always been quick and helpful in resolving the warranty claim. A friend of mine lost his L2 rocket to Pro CATO at NYPower, and again, CTI was a class act.
Good luck to you, and I am sure your next attempt will be a success. I always hate a failed cert attempt, more so when the flyer is 100% not at fault.

Todd

Well, Sept 14th came and went... and I did not launch My MegaBlast.

Robert DeHate did a very good job repairing the damaged from the pro38 cato... he glassed the damaged tube... filled it.. primed it... and painted it. I picked it up last Thursday and added the "LAST" to to the name... You can almost not tell that the tube was damaged. Thanks Robert....

What delayed the launch then? My order to Magnum. I ordered a new altimeter bay, some tubular kevlar (to replace the nylon). I asked magnum to ship the order when he gets my repaired buzzer to save on shipping... Well, he got it back Wednesday... and he shipped my package out 2 Day Air so I can get it Friday... But UPS was late... and I got it Monday... 2 days after the launch

That means that MegaBlast launch date has been moved up to October 26th 2002. Since I have over a month till the new launch date, I went ahead and called Aerotech… and said I wanted to go through the warranty replacement process for the propellant grains for my J350 motors.

It looks like I don’t have to pay for anything… except for the extra parts I asked for... I have 6 grains that Aerotech says will blow up if I try using them for my J350 motor…. However… they will work fine with the smaller motors… So.. when Aerotech sends me the new grains… I will take the six old grains, and the parts I ordered… and I’ll make two I161 reloads out of them. So when October 26th arrives… I will test-launch my altimeter with an I161 powered rocket… the other I161 will be used in my Target rocket, and the J350 will be used with my MegaBlast… and hopefully… I’ll gain my certification

Picture of glassed tube.

Picture of filled tube.

My new LOC 4" altimeter bay is built and ready to go. I did a few things different with this electronics bay than with the one I built during the first attempt. I decided that I did not want the bolts to screw right into the paper. So I used Blind nuts to give the bolts something to screw into. After drilling the three holes, I had to recess the blind nuts so the assembly can fit in my 4" birds, but this was easy. All I did was cut out square windows in the tube coupler, and the blind nuts were hammered in and CA'ed in place.

Like I have done with all my other electronics bays in the past, I used "banana plugs" Binding Posts for the electrical connections. This offers a solid electrical connection to the igniter charges.

One other thing I had to think about was how to attach the arming switch to the LOC 4" payload section? I could use the switch I had before, but I am uncomfotable using a sliding swith... its easy forgeting to turn it on, and it might shift possitions in flight. The stuffer tube was extremly thick, so I thought it would be difficult connecting a phono jack to it. So, I went looking for something that I thought would work...

I found it at radio shack . A rectangular phono jack... Aftering soldering the two wires to their proper posts, I cut a slot in the tube coupler, and epoxied the jack in place.

I now have a usable J350, and my altimeter bay seems to work. All I need to do is attach the recovery harness... and the MegaBlast is ready to fly again :-D

Looks good. Best of luck on your next try

Doug, keep us up to date on your L2 and good luck to you!

Carl

FWIW, stereo jacks are really no better than switches. In fact, if the altimeter is "power jitter prone", you'll be worse off with a jack and a switch.

the little contacts that the jack breaks when you insert a plug, are well known to corrode and also they are very G sensitive. Make sure if you use them that they are mounted at 90 degrees to the thrust vector. At apogee and the deployment phases, you just never know. If the Atlitimer will survive a brief power outage, you'll be ok, but if not... it will reset and you'll be in trouble.

Just my .02

Alan

I have to agree with Alan. I bought some of those stereo plugs, which are a great idea BTW. But after looking at it I found that if you face the plug the wrong way, the G force could force the leads apart which will turn off the altimeter. At least that is what I thought so I went with Type-3 key switches where the key is held firm when the altimeter is off. Turn the key and it turns on the altimeter and the key is released to pull out. Because it is a "rotary" switch, G force and jitter do not play a part. I wish I could find the link. Unfortunately with my web page down I can't get to it. I will check into it and get back with ya.

Carl? Can you send the link?

BTW: Your rocket looks beautiful dude.

I hadn't thought about commenting on the switch, as I never use a phono jack for a power connection. I have used them to break the lines to the charges, where momentary interruptions early in the flight or on an ejection even will not hurt. (Many will advise against this application too, but I'm stubborn )

BTW, my G-Wiz will run a long time on a full battery so there isn't much of an issue with leaving the thing connected while waiting for a pad.

I've heard quite a few people say you shouldn't even use key switches. These people have devised home-brew screw terminals to get a secure contact. I haven't paid enough attention to see what class rockets they were talking about. I suspect the biogger the motor(s) the more chance there is of having a problem.

I have seen alot of people use key swithces on rockets. i never have heard of any problems in using them. The same goes for Phono plugs. The Gates Brothers use them in all their rockets and have never had an electronics failure.

Here's a link for you.
https://server50.hypermart.net/binderdesign/upgrades.html
I purchased some but have yet to use any in flight so I can't comment on usage. I've also seen a few used without issues and in my opinion is a nice finishing detail. I also see others in preparation for an L2 or L3 flight twisting wires together on the pad. Sometimes the simplest method is the safest and most reliable method. It may not look pretty but if it works...

Paul

I have to agree with PAH that the simplest method is sometimes the best. Twisting wires together is about as simple as it comes. I have a L3 friend in NC that has used this method for a long time. He twists his wires together to arm, then tapes them up and shoves them back in the hole they are hanging out of. Another friend and L3 here at home has flown for many years now including some of the LDRS and always twists his wires together, but he just tapes em to the side of the rocket and lets them hang out for the ride.

I have used a method that has even eliminated the wires...with my CPR3000, a jumper is moved and directly placed on the power pins to power up the altimeter, then it is inserted into its bay, the two halves are screwed together and the rocket is placed on the pad. I use Adept Altimeters with motion switches, so they don't arm until the rocket is moving forward, thus allowing me to turn them on this way.

Key switches are also coming more into play these days. I have used the same keyswitch that Phil noted on models including my L3 cert rocket with great success. The Type 3 switches are the ones I like the best so far; they remove only in one position, allowing you to wire them so you HAVE to remove the key(with big arse flag) in order to arm and they "snap" into position. Here is the URL:

https://www.aeroconsystems.com/electronics/switch-key.htm

This place also has a new "Type 2" I want to take a look at...the features are pretty cool with multiple connectors.

Finally, the Phone Jack method is also popular, because of the ease of use and flush mount. This doesn't mean it is good though and it IS prone to vibration; even if the Gates Bros use it(and not trying to take anything away from their efforts as they are great builders), that doesn't make it safer...and they haven't flown them but a few flights each so far, not allowing for them to weather, tarnish or wear, which will happen over time. Something you could do, and being a HAM operator you probably already thought of this Doug, is to use a 1000uf or larger capacitor across the power leads so if the switch momentarily disconnects, power will be drawn from the cap allowing the circuitry to continue to operate. Note that most vibration connection problems are for thousandths of a second and a Capacitor could play a big part in increasing reliability during this time.

Hope this helps,

Carl

We'll I just want to mention that I have been using phono jacks for my electronics for years (mostly launchers... now internal elctronics)... and the only problem I had with them is they seem to ware out. When I went shopping for a good phono hack, I noticed that this designed looked nice and sturdy... and also the metal in the switch looked stronger than other 1/8" jacks I have seen. I personally don't think G-Forces will have much effect on this switch... even though the rocket is 4" dia, it weighs 7 - 8 lbs... its subsonic. If I was expecting mach speed, I would use something different. Just my opinion....

The Doug

Doug, as with many things in life, you have a wide variety of advice. This has been discussed ad-nauseum on r.m.r and the concensus is probably not to use this type switch on power connections. However, this is not a given. It does seem that Carl's idea of adding a cap is cheap insurance.

Carl - I used one of the Aerocon two pole switches on my Upscale Big Brute. It's nice to break both charge lines with one switch

Here r some updated pictures of my MegaBlast:

These are some pictures of the electronics bay. It is a modified LOC 4" electronics bay.

The electronics bay

The inside view of the electronics bay.

Here are some photos showing the recovery profile of the MegaBlast. Both the drouge and main chute sections have the same basic design. Tubular kevlar is used to anchor the shock cord to the rocket. A short piece of bungee cord is used to absorb deployment shock. A longer piece of tubular nylon is used to back up the bungee cord. The Drogue section has a Trans Beep connected to it. The drouge is a 28" x-form chute. The Main chute is a 45" chute ordered from Magnum. The nosecone, is now solid. There is 1 lb of clay in the tip. The shock cord is ancord to the nose via a tubular nylon strap that goes all the way down to the clay in the nose cone, which contains several knots. The void in the nose cone is filled with PML expanding foam.

Now that the photo's are taken... it is time to move the ectronics bay to my EZI... and get it ready for its I161 test flight.

The Megablast showing its recovery profile.

The drogue section.

The main chute section

Looks like you're ready, dude!

Guess what!? I am now in the ranks of L2. The Megablast flew successfully on a J350-14W to about 2500 ft. Both the drouge an the main deployed at apogee... but the rocket landed in the field. Video and pictures coming soon

The Doug

May I be the first one to tell you... CONGRATULATIONS!!!
I know the feeling you get when you certify level 2. Before the flight you feel like you've got a 50 pound weight on your back with all the anticipation, until the flight. Your rocket lifts off, coasts, deployment... The flight was successful, you feel lighter than air as that wieght is now gone( your wallet is now feeling the same way) .

Once again congratulations!Best of luck onthe projects that WILL come!

rocwizard

congrats doug

glad I was there to see it!

Originally posted by n3tjm
Guess what!? I am now in the ranks of L2. The Megablast flew successfully on a J350-14W to about 2500 ft. Both the drouge an the main deployed at apogee... but the rocket landed in the field. Video and pictures coming soon

The Doug

Click to expand...

Doug, not to burst your bubble, but I just went thru this. Technically, if both the main and the drogue opened at apogee, that shouldn't have passed. You may have gotten lucky with whomever witnessed your flight. Unless you loaded up and flew again and the deployment worked as slated.

Now, before I go to deep in this, let me ask. Did you want both to open at apogee? If so, then you passed, but if you expected the drogue to open and then the main at some altitude specified by the altimeter, you didn't (technically).

I should know, I went to a launch at Oburg a month ago and a guy was going for his L2. He flew the first flight on a J360 Pro38, great flight, but the FinCan separated and it came in hot. No damage, but didn't pass, reconfigured, stuffed another J360 in and tried it again, and this time the drogue and main opened at apogee, wouldn't pass him on that one either. Last flight after much debate was with a J350 and this time, all worked as planned and he went home L2.

On my L2 flight, just two weeks ago, again, the L3 and L1 that certifed me asked if I was expecting main at apogee or at altimeter. I said the later, and few the flight, it worked as planned and I as well was certified. But had the main come out at apogee, no joy.

None of the above matters if it stays on the field or not I don't believe, it has to do with configuration and flying the flight you specify and it being successful.

I'm curious of others thoughts on this topic as well, and also curious Doug, of your original flight intent.

Congrats, but I'd say you were lucky if your description was indeed the only flight that you took and if the outcome was as you mentioned and yet you expected main at some lower alt.

my .02. Not trying to be the cert police, I just know how hard people work and what they have to go through

Your thoughts on the topics? Or clarifications?
Alan

Way to go, man! Glad things went well!

My understandings of the rules... if you get the rocket back in a condition that you can refly the rocket by just reloading... you pass. The only damage that is allowed is small zippers. Main deploying at would not DQ you ... just means you go on a longer walk. But litterely... if I had another J... I could fly it again as is...


Prove my point... here is what the HPR form says:

Flight

Model is stable

Click to expand...

(check) - flew straight as an arrow.

Recovery system deployed

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(check) - under two chutes

Safe Recovery

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(check) - Not a scratch

Post Flight

Verify that no major damage is present. Minor impact damage or "zipper" is acceptable.

Click to expand...

(check) - Not a scratch.

Verify motor(s) is (are) present

Click to expand...

(check) I can give Robert his case back.

Ok... so the actual form is general... what about the actual rules in that two page pamphlet you get? Is there anything in there about this issue... lets check:


NAR CERT PROGRAM

The individual will fly his model. The flight must be witnessed by the certification team members. Stability, deployment of the recovery system, and safe recovery should be considered when evaluating safety of the flight. Models experiencing a catastrophic failure of the airframe, rocket motor, and/or recovery system (e.g., shock cord separation) will not be considered as having a safe flight.

The model must be returned to the certification team after flight. and be inspected to verify engine retention and for evidence of flight-induced damage. The certification team will initial the blocks indicating that a safe flight was made and that the post-flight inspection was satisfactory. In general, the guideline for acceptable flight damage is that the model could be flown again without repair. It is left to the judgement of the certification team to differentiate between flight damage and "normal" maintenance to assure reliability (e.g., shock cord replacement to prevent future flight problems). "Zippering" of the body tube is another area of flight damage left to certification team judgement for acceptability.

Click to expand...

Note the line: "In general, the guideline for acceptable flight damage is that the model could be flown again without repair."
Sounds familiar doesn't it?


Now what about : "Models experiencing a catastrophic failure ... recovery system (e.g., shock cord separation) will not be considered as having a safe flight." Well, the recovery system did not fail... it held together and brought all three pieces back together.

As stated, not picking or being the Cert police, I'm as new at this as anyone, only relying upon what I've been told. Course, it could be TRA vs. NAR. I did cert TRA. Maybe NAR is a little more relaxed?

Congrats none the less, don't want to take away from the moment. I know what it feels like!!! Woo hoo..

Alan

Ps. I did a little researching before I posted this. I'm betting it's NAR vs. TRA that is different. See Item D. below from The TRA site.

Certification Level 2
Allows all Certification Level 1 activities and purchase and use of J, K and L solid or up to L hybrid motors for your consumption only, act as RSO and be a Prefect. EXCEPTION: A Level 2 Member may purchase one M, N or O motor for the purpose of Level 3 Certification.
Allows staging and clusters for rockets up to 10240 Newton-second total impulse (M equivalent).

Certification is accomplished as follows.
A. Pass the Certification 2 written rocketry examination prior to the certification launch.
B. Allow detailed inspection of their certification rocket and discuss its construction with a RSO.
C. Successfully launch and recover a J, K or L rocket per the certification criteria.
D. Recovery is defined as full deployment of the recovery system used as designed The rocket need not be returned if the rocket is inaccessible.

A CATO disqualifies because it may have been due to improper construction or improper prepping.
A Shred disqualifies because it occurs due to improper construction of improper motor selection.
An Authorizing Person does not need to sign for whatever reason. (An Authoring persons signature only means that they have observed you conduct a Certification 2 flight successfully and establishes your Level 2 Certification.

Must abide by the Tripoli Rocketry Association (TRA) Bylaws, Safety Code and Operating Rules.

I know that for TRA L3 the rocket must perform AS DESIGNED. I can't check for L1/2 since that part of my form resides with TRA HQ And since its TRA I couldn't find this on their site. .{while typing I missed the previous post...evidently I missed something on the TRA site , my bad}

I looked over the NAR L1/2 paperwork, and see nothing about the recovery system performing as designed...only what Doug recited above. In fact, I got this from the NAR L3 web page:

d) The rocket shall fully deploy its recovery system. An anomalous deployment of the recovery system is not cause for flight rejection if the model descended in a safe manner. It is up to the judgement of the Flight Witnesses whether the model descended in a safe manner.

So, even for a NAR L3, accidental deployment of the main at apogee is not a problem

Learn something everytime. ... Seems to be a distinction between NAR and TRA.

Most all the people that I talked to before I certifed said if I flew dual deployment, it had to work as stated or it would fail. That's why most suggest strongly, that you use the KISS principle and not fly electronics on an L2 cert flight.

But I like Doug, just couldn't resist.... Now, the problem is I'm hooked big time!!! :> May never go back to motor ejection again... well there are those estes kits that I have to build.

Alan - Learning along the way... sorry Doug

Dick is correct in the fact that this is a big difference between NAR and TRA...

TRA is very picky about the rocket working as designed! Alan is right here and I have seen more than one person get turned down as the deployment did not work correctly, even for L2. For L3 your TAP WILL ask you how you expect the recovery system to work.

As far as NAR goes though, being one who has certed many L1 and L2 fliers for NAR, you are correct in the fact that the model needs only to recover in a safe manner and without enough damage to preclude another launch. Doug, you listed it step by step on all those little spots on the NAR cert for I have to fill out and that is how it is...so you get a break here with the NAR.

Now, back to the important stuff...

BIG CONGRATS doug on your L2...patience and persistance have paid off for you bro, glad to hear it. You BETTER get us some pics and movies!

Well Done Doug,

Carl

aadamson -> Being a NAR member... I assumed that you were talking about the NAR program... I forgot about TRA... I guess its been a while since I was a TRA member...

Originally posted by n3tjm
aadamson -> Being a NAR member... I assumed that you were talking about the NAR program... I forgot about TRA... I guess its been a while since I was a TRA member...

Click to expand...

hehe... Congrats again... yeah, I know, only reason I joined TRA was so I could do EX... But as they say "Now prepare your pocket book.... You get to spend big bucks to fly".

BTW, try one of those CTI J330 Pro38's they kick some serious butt!!! One of my favorite motors and now with the Smokey Sams out, they'll be even more fun.

Alan