Minimum diameter level 1 rocket questions

[Liam Steele]

Hello,

I am currently designing and building a 54mm fiberglass level 1 minimum diameter rocket using an AeroTech I65W-PS Single Use DMS motor. I have a couple of questions regarding the design of this rocket:

1. In OpenRocket my current simulation is being designed with a stability caliber of 1. This rocket will have an apogee of around 8000 ft with a max velocity of around mach 0.80. Would I be safe with a stability caliber of 1 or should I aim for something more than 1, and if so, what would be a good number to target?

2. I originally wanted to retain the motor using an AeroPack 54mm minimum diameter retainer, but those two parts are not compatible. I am trying to figure out a good way to retain the motor in the rocket. Any suggestions?

Thank you,
Liam Steele

 

[smstachwick]

Hello,

I am currently designing and building a 54mm fiberglass level 1 minimum diameter rocket using an AeroTech I65W-PS Single Use DMS motor. I have a couple of questions regarding the design of this rocket:

1. In OpenRocket my current simulation is being designed with a stability caliber of 1. This rocket will have an apogee of around 8000 ft with a max velocity of around mach 0.80. Would I be safe with a stability caliber of 1 or should I aim for something more than 1, and if so, what would be a good number to target?

2. I originally wanted to retain the motor using an AeroPack 54mm minimum diameter retainer, but those two parts are not compatible. I am trying to figure out a good way to retain the motor in the rocket. Any suggestions?

Thank you,
Liam Steele

CP tends to move forward due to compression effects at certain Mach numbers. This effect shouldn’t be too pronounced at the subsonic speeds you’re reaching, but it might be worth checking in OpenRocket.

I have no suggestions for the retainer, as I’m not building in that size range just yet.

 

[cls]

Use a few strips of good (brown) 3M masking tape on the motor, to friction fit it in the rocket.

Can also put a wrap around the end of the rocket and the motor thrust ring.

Don't use blue, green, or other masking tape. And don't let duct tape anywhere nearby!!

 

[Sooner Boomer]

I've got a 38mm min. dia. build underway, and a 54mm MD planned for next year. What I'm doing is to use a hex aluminum standoff, embedded in the aft root of each fin. They don't have to hold up to much. I'm using a #4-40 for the 38mm and #6-32 for the 54mm. A machine screw with a washer is used to actually hold the motor in place.

Something like this, except that the standoffs are mounted under the fins...

 

[Steve Shannon]

I've got a 38mm min. dia. build underway, and a 54mm MD planned for next year. What I'm doing is to use a hex aluminum standoff, embedded in the aft root of each fin. They don't have to hold up to much. I'm using a #4-40 for the 38mm and #6-32 for the 54mm. A machine screw with a washer is used to actually hold the motor in place.

Something like this, except that the standoffs are mounted under the fins...

View attachment 648363

Dr. John Story showed me a minimum diameter rocket he built once that had bike spokes embedded in the fillets so the threaded portion stuck out past the motor thrust ring, allowing him to use tiny hooks to hold the rim. It was pretty slick.

 

[charrington]

Labrat rocketry minimum diameter retainer or an aeropack minimum diameter retainer. I typically dont use these and go for a friction fit. I also dont see a point in designing a whole rocket around such a small 54mm motor. Figure out what the largest motor you want to use in it is, and design your stability around that. I recommend not dipping below a stability of 1.75 - 2 cal on supersonic flights. Check with both open rocket and rasaero.

 

[bjphoenix]

I've got a 38mm min. dia. build underway, and a 54mm MD planned for next year. What I'm doing is to use a hex aluminum standoff, embedded in the aft root of each fin. They don't have to hold up to much. I'm using a #4-40 for the 38mm and #6-32 for the 54mm. A machine screw with a washer is used to actually hold the motor in place.

Something like this, except that the standoffs are mounted under the fins...

I built my first LOC kit with 29mm mount using a couple of T-nuts in the rear ring and I made a big aluminum washer that would fit over the engine nozzle and had 3 holes for screws to go into the T-nuts. A few builds later I had the idea that I could make a wire retainer to use with the bolts and T-nuts. That rocket used 2 bolts instead of 3. I screwed the bolts in and wrapped wire around them- around one bolt then around the nozzle then around the other bolt then back, a few times. It worked well. The resulting wire looked like a figure 8 but with 3 openings, the center opening larger than the outer 2 openings. I think this could work for minimum diameter- put inserts or threaded rods in the fin roots and make a wire shape to fit over the motor like I described. My retainers like this were used with Aerotech G through I RMS motors, it would take a little more work to make the wire retainer to fit the Aerotech motors with more complicated nozzles.

 

[Neutronium95]

Hello,

I am currently designing and building a 54mm fiberglass level 1 minimum diameter rocket using an AeroTech I65W-PS Single Use DMS motor. I have a couple of questions regarding the design of this rocket:

1. In OpenRocket my current simulation is being designed with a stability caliber of 1. This rocket will have an apogee of around 8000 ft with a max velocity of around mach 0.80. Would I be safe with a stability caliber of 1 or should I aim for something more than 1, and if so, what would be a good number to target?

2. I originally wanted to retain the motor using an AeroPack 54mm minimum diameter retainer, but those two parts are not compatible. I am trying to figure out a good way to retain the motor in the rocket. Any suggestions?

Thank you,
Liam Steele

You can use a 3/8" NPT tap in the forward closure, and then thread in a 3/8" NPT to 5/16-18 adapter and you'll be able to connect to the retainer.

I generally aim for keeping the CG 10% of the body length above the CP for the entire flight. 1 cal feels pretty low for a minimum diameter rocket.

Do you have experience flying with deployment electronics? This flight will require electronic deployment, and will almost certainly need dual deploy due to the high altitudes it'll reach.

I'll also echo @charrington and say that if you're building a 54mm minimum diameter rocket I'd say to make it long enough to fit longer motors, at least up to a 4 grain motor.

 

[Bob Yanecek]

Make your fin can shorter than the motor such that the forward end of the motor serves as the coupler to the upper airframe. Attach recovery harness to the forward closure of the motor. Take a stab at friction fitting the motor but, if it slips back/out, that will serve the purpose of separating the fin can.

 

[Choco_mint]

Is this a certification flight? If it is, I'd strongly recommend using a different approach, unless you already have experience with Dual Deploy/have a mentor who has successfully pulled off a high-altitude MD flight before. I've learned that some projects need a lot of forethought and lots of test flying to make them work (due in part to wise words from many people on this forum!)

Good luck!

 

[Liam Steele]

Thanks for all of the feedback! Another couple of question: this rocket will use a dual deploy recovery method, but what would be good size or target descent rates for the main and drogue chutes? I am planning on using a TeleMetrum as the primary flight computer, along with a backup flight computer of some kind. Any suggestions on alternate avionics?

 

[bad_idea]

Do you have experience flying with deployment electronics? This flight will require electronic deployment, and will almost certainly need dual deploy due to the high altitudes it'll reach.

Calls for a tracker too, though last weekend I saw a fellow get a minimum diameter 38mm rocket that flew over 10k back without one. (Everyone, including the flier, was surprised.)

 

[Choco_mint]

Without a tracker is actually insane to think about, hats off to the weather gods for keeping the winds low!

 

[Rocketjunkie]

Talk with whoever is going to be the certifying witness. They may not be able to see the whole flight and may want you to go lower. Adapt to a small H for the cert flight and then go with the I65 (or K270).

 

[ksaves2]

Do a larger diameter single deploy rocket that is better suited for a cert flight. When the certification is under your belt, start doing the high flying with DD and hopefully a tracker of some kind to get it back. I've seen that philosophy used on a 16 inch diameter L3 attempt that was single deploy and went to a total
of 1100 feet! No law against that. The booster came back on three monstrous parachutes that were surplus, previously man rated and the NC came down on 3 twelve foot chutes. Was a sight to see.
You don't have to do anything like that but better to keep within sight using weight and size as your friend. When accomplished as mentioned then go high flying MD keeping in mind the off-nominal flight risk and loss rate goes up no matter how well prepared one is. KISS is the way to go to get the cert. Kurt

 

[SolarYellow]

I'm not certified, but working on it. I view it differently. I have zero interest in burning expensive motors to go low and slow. My HPR interest is to go high and fast, so to me, it's logical to work my way up to that and make the cert flight reflect the kind of flying I intend to do after I have the cert. Another advantage is that my L1 build can be flown "low & slow" on MPR and even the top end of LPR motors to watch the deployment happen and make sure it's uber-reliable and works exactly how I want it to work, as well as practice using the GPS tracker. And get my checklist down. I can fly it that way as many times as I like at very low cost per motor and then, when I'm satisfied that everything is groovy, turn up the impulse in steps. An H128 or H135 won't be that much more radical than a G80, and I'll have plenty of experience recovering it from out of sight flights before the cert flight.

 

[kjhambrick]

I'm not certified, but working on it. I view it differently. I have zero interest in burning expensive motors to go low and slow. My HPR interest is to go high and fast, so to me, it's logical to work my way up to that and make the cert flight reflect the kind of flying I intend to do after I have the cert. Another advantage is that my L1 build can be flown "low & slow" on MPR and even the top end of LPR motors to watch the deployment happen and make sure it's uber-reliable and works exactly how I want it to work, as well as practice using the GPS tracker. And get my checklist down. I can fly it that way as many times as I like at very low cost per motor and then, when I'm satisfied that everything is groovy, turn up the impulse in steps. An H128 or H135 won't be that much more radical than a G80, and I'll have plenty of experience recovering it from out of sight flights before the cert flight.

I feel the same way about it.

A cert is just a piece of paper and a pin for your drawer ( or for your young granddaughters )

Why build and fly a rocket to fly low and slow just one time simply to get a certification and then never fly that rocket ever again because you're into speed and altitude ?

If ripping flight is your cup -o- tea then why not certify that way ?

As @SolarYellow said, that same rocket can fly low and slow on a smaller motor until you've developed your techniques ( dual deployment and tracking ).

And if it takes more than one attempt, so be it -- you can buy as many L1 motors as you need until you get certified.

And the same is true when it comes time to certify L2.

Just my $0.02 ...

-- kjh

 

[ksaves2]

I'm not certified, but working on it. I view it differently. I have zero interest in burning expensive motors to go low and slow. My HPR interest is to go high and fast, so to me, it's logical to work my way up to that and make the cert flight reflect the kind of flying I intend to do after I have the cert. Another advantage is that my L1 build can be flown "low & slow" on MPR and even the top end of LPR motors to watch the deployment happen and make sure it's uber-reliable and works exactly how I want it to work, as well as practice using the GPS tracker. And get my checklist down. I can fly it that way as many times as I like at very low cost per motor and then, when I'm satisfied that everything is groovy, turn up the impulse in steps. An H128 or H135 won't be that much more radical than a G80, and I'll have plenty of experience recovering it from out of sight flights before the cert flight.

That in my opinion is the wrong philosophy. It might take forever to get the cert if one is going in that direction due to inflight "anomalies" structural failure, loss of rockets, etc. If one is sticking to manufacturer related kits for motor impulse recommendations then that's o.k. if one has the money.

I was taught and maybe it's because I'm a "flat lander" in Central Illinois with limited large launch sites. After certing, I didn't care about motor cost as I learned to mix my own motors. Yeah, I can't/don't fly'em at NAR sites but since I bought the "fix'ins in bulk my motors are cheaper now as I've done it for a long time. I keep some "cert'ed motors" to go to NAR launches. Fly the lowest powered motor in an approved rocket and get it done! Then go designing on your own! Stupidhead, fly low and slow one time to get the cert and then go crazy with whatever you want!!!

I flew a pile of DD L1 rockets after I certed on a motor deployed SD rocket and screwed up on a DD L2 attempt. Messed up on the apogee ejection charge in a 4" cardboard tubed rocket and blew out the side of the booster! Rocket did a "death dive". Had one of the early keychain cameras on the side and I laughed my head off when I first saw it . When the main blew it was a big zipper time of the upper bay and a failure at certing. Went back to RockSim and designed a single deploy cardboard tubed rocket and had success on a motor deploy venerable J-350. I told the prefect since the sim said I needed a shorter delay, I drilled it a "tiny bit". He didn't mind as he attended the same motor/propellant mixing class as I did. Yes, I used an AT certified J-350 but tweaked the delay grain a "little bit". Flight was excellent and I still have that rocket. At the LSO table they didn't know the difference.

Keep it low and slow. Diameter and weight can be one's friend if certifying cause if one can't bring the rocket back in a flyable state, it's no cert!

Get the cert and then do whatever you want within the impulse range one is certified on. It's a learning process.

Your philosophy is defective.

Kurt

 

[bad_idea]

That in my opinion is the wrong philosophy.
<snip>
Your philosophy is defective.

"Wrong" and "defective" are mighty strong words for something that works just fine for many other people.

Personally I'm not all that reassured that a newly-minted L1 knows what they're doing if their cert flight was the bare minimum giant motor eject rocket, but if the organizations were too concerned, they'd raise the bar. To each their own.

 

[loopy]

I feel the same way about it.

A cert is just a piece of paper and a pin for your drawer ( or for your young granddaughters )

Why build and fly a rocket to fly low and slow just one time simply to get a certification and then never fly that rocket ever again because you're into speed and altitude ?

If ripping flight is your cup -o- tea then why not certify that way ?

As @SolarYellow said, that same rocket can fly low and slow on a smaller motor until you've developed your techniques ( dual deployment and tracking ).

And if it takes more than one attempt, so be it -- you can buy as many L1 motors as you need until you get certified.

And the same is true when it comes time to certify L2.

Just my $0.02 ...

-- kjh

Why would you never fly that rocket again? Personally, I make choices to give myself the best chance of a successful cert flight knowing I can really push the rocket later. Even on L2 - fly it on a small J, then let it rip with an L if you want. Just because the cert flight is low and slow doesn't mean the rocket can't rip later.

 

[Liam Steele]

Hello,

I am currently designing and building a 54mm fiberglass level 1 minimum diameter rocket using an AeroTech I65W-PS Single Use DMS motor. I have a couple of questions regarding the design of this rocket:

1. In OpenRocket my current simulation is being designed with a stability caliber of 1. This rocket will have an apogee of around 8000 ft with a max velocity of around mach 0.80. Would I be safe with a stability caliber of 1 or should I aim for something more than 1, and if so, what would be a good number to target?

2. I originally wanted to retain the motor using an AeroPack 54mm minimum diameter retainer, but those two parts are not compatible. I am trying to figure out a good way to retain the motor in the rocket. Any suggestions?

Thank you,
Liam Steele

I have another couple of questions that I figured I'd ask as I'm trying to learn as much as possible before I start building and flying this rocket:

1. This rocket will use a dual deploy recovery method, but what would be a good size or target descent rate for the main and drogue chutes?

2. I am planning on using a TeleMetrum v4.0 as the primary flight computer, along with a backup flight computer of some kind, and maybe a couple of onboard cameras. Any suggestions on alternate avionics or good backup flight computer choices?

Thanks again,
Liam Steele

 

[ksaves2]

"Wrong" and "defective" are mighty strong words for something that works just fine for many other people.

Personally I'm not all that reassured that a newly-minted L1 knows what they're doing if their cert flight was the bare minimum giant motor eject rocket, but if the organizations were too concerned, they'd raise the bar. To each their own.

If flying a bulletproof "glass" rocket that could stand an excess of a deployment charge fine. Can use a standard "charge" and not worry about it. With the cheaper not reinforced cardboard rocket one could get it to blow out the side and not "up" for recovery/chute deployment. Oh, probably most attempts above L1 are likely 'glass and charge"s" are less an issue at this time. I have to apologize I started in "94 so come from that mindset. Kurt

 

[kjhambrick]

Why would you never fly that rocket again? Personally, I make choices to give myself the best chance of a successful cert flight knowing I can really push the rocket later. Even on L2 - fly it on a small J, then let it rip with an L if you want. Just because the cert flight is low and slow doesn't mean the rocket can't rip later.

I suppose I didn't express myself very well.

What I meant is this:

I've seen a lot of advice to build a fat and heavy rocket and fly a low-end motor just to get certified by flying low and slow.

I know if I followed that advice I would fly that rocket one time for a cert then put it in the attic and never fly it again because what I want to do is to fly as fast and as high as my site and my budget will allow.

To me the cert is all about the journey and not the event of receiving the cert itself.

Having said that, there is something to what @ksaves2 said about reaching L2 because it will allow one to fly experimental motors or to buy RCS propellant grains and fly those but that is L2 and not L1.

-- kjh

 

[SolarYellow]

Your philosophy is defective.

The point of the cert is to denote proficiency in the type of flying that a person will do once certified.

My philosophy is to acquire proficiency in the type of flying that I will do once certified, so that the certification flight itself is just another flight that happens to be demonstrating that proficiency. There is no penalty if something goes wrong that is any different than it would be on any other flight. It's not like I have to pay the prefect a $100 fee every time I say, "This is my cert flight." If I fail to recover the rocket, or it has a non-nominal flight or is damaged otherwise, the penalty in time and treasure is exactly the same as if I was already certified, except that more people will be watching. But with my plan, I will already have flown and recovered the rocket many times, watched the exact deployment hardware and software function at low altitude, etc. So the risk will be very well managed. The point is to be proficient, so that managing the risk is baked into the pie.

The point of the cert isn't the piece of paper, it's getting myself and my program to the point where doing the thing that the piece of paper says I'm qualified to do is not a big deal.

We'll just have to disagree, I guess.

 

[boatgeek]

I've seen these discussions a lot. My take is that going low and slow is definitely safer and more likely to result in a certification. However, if a flyer goes in to minimum diameter with their eyes open on the risk of failing certification, I don't see why to close the door. It would be a good idea to practice dual deployment on a smaller rocket prior to attempting the certification.

Typical descent speeds under drogue are 80-100 FPS, and 20-25 FPS under main. The latter depends heavily on what kind of terrain you're landing on. Sod is far more forgiving than concrete or dry lakebed. Remember that you need to keep the fins on in order to get your certification.

Retention can also be tape over the back of the airframe and the thrust ring on the motor. I have personally had success with electrical tape pulled tight, and I know I've seen people who have had success with aluminized tape for HVAC ducting. Retention via a bolt forward is probably more secure.

 

[ksaves2]

I have another couple of questions that I figured I'd ask as I'm trying to learn as much as possible before I start building and flying this rocket:

1. This rocket will use a dual deploy recovery method, but what would be a good size or target descent rate for the main and drogue chutes?

2. I am planning on using a TeleMetrum v4.0 as the primary flight computer, along with a backup flight computer of some kind, and maybe a couple of onboard cameras. Any suggestions on alternate avionics or good backup flight computer choices?

Thanks again,
Liam Steele

If you're using a fiberglass based rocket with electronics you're in decent shape. Don't use metallic paints as it will shield the Rf from the tracker getting out. I've been there a few times with 400Mhz stuff. Don't use metallic paints on a bay where the antenna projects into. Never got a tracking signal and happy to get the rockets back as they landed withing sight of somebody. Don't repeat my mistakes! If putting a "hardened" APRS tracker on an apogee harness, the antenna might get bent and affect the range of the tracker. Be aware of that.

I went to a nosecone mounted tracker of the APRS or even an NMEA type on the non-licensed required range. AS LONG AS THE NOSECONE IS NOT PAINTED IN A METALLIC PAINT! The back end of the rocket can be a beautiful metallic scheme as long as the nosecone does not have metallic paint on it
with a nosecone tracker!

Even so some folks say metallic paint is not a problem, I don't care. Don't do it as I was burned back in the day before folks realized it was an issue.
Nosecone mounting is a trick as one needs to prepare a "motor mount" bulkhead with a "hole in the middle" and epoxy it securely in the nosecone.
before epoxying it, they need to prepare a solid bulkhead of the same overall diameter as the "hole in the middle bulkhead".
Then use a drill press to drill 6 equal spaced holes around the perimeter in the "motor mount" with a hole. Then temporairly secure the motor mount bulkhead to a solid bulkhead securely for drilling and use the holes to line up and drill holes in the solid bulkhead.
What one ends up with is a bulkhead with a hole in it they can epoxy (I use aircraft grade) inside the nosecone after I put blind nuts on the backside and can then screw in a solid bulkhead with screws to make it removable. The eyebolt is in the middle. I do "pilot" marks with magic marker for alignment after drilling
both ring and bulkhead.

I can mill/cut a clearance on a tracker board for the eyebolt. That way I can pre-prep the tracker board for the tracker I'm going to use for the screw holes/blindnuts and such. Then, I epoxy the tracker board to the bulkhead at 90 degrees with the eyebolt intact. To use a wider tracker board, I use a dremel to mill some groves on the motor mount type bulkhead in the nosecone.

This is tough to understand but basically I use a "plywood or fiberglass" motor mount ring and epoxy it inside a nosecone. EXCEPT, I pre-prep a solid bulkhead to line up to the blind nut screwholes on the ring securely epoxied inside the nosecone. The tracker carrier with clearence is epoxied 90 degrees to the solid bulkhead that carries the screw eye. On a 4 inch rocket, I was able to mill slots on the epoxied nosecone bulkhead to accommodate a wider tracker carrier.

Simply, one has removeable nosecone tracker carrier. It also works for smaller diameter rockets say like a regular "Wildman" but is a tighter fit and have to invest in a smaller tracker to fit. Smaller rockets of course can't accommadate this.
Later on in time when the cheaper "moldable" fiber-optic endoscopes were available, I was able to visually inspect inacessible places in rockets to confirm I had a good bond. Plus!!! on the rockets that I didn't have wire or internal harnesses in and flown for a long time, I could inspect their internal attachment points as kevlar does get worn. Very helpful with older rockets with fiber/kevlar attachments in the booster. I switched to cable/wire internal chute attachments a long time ago as they are more robust if permanently installed. If the rockets survive in that case, can detach the kevlar from the internal metal harness lead and put new kevlar on before it fails.

No, no, no! I likely wasn't the first one to do this as I'm sure many did it when cheap endoscopes became available before me. When I was in medical training I got to look through some probably multi-thousand dollar high-resolution endoscopes and when the cheap mail-order ones came out, they were more than adequate to look inside a body tube to survey damage or inspect shockcord integrity with "glued-in" cords.

Still have one downstairs. Very cool to look inside a well flown "surviving" rocket. Kurt

 

[FredA]

My philosophy is to acquire proficiency in the type of flying that I will do once certified, so that the certification flight itself is just another flight that happens to be demonstrating that proficiency.

OR - to put it another way - USE the cert process and the mentors provided within to gain the proficiency needed for your desired style of flying.
As I've often said - the L3 "gateway to unlimited flying" is also the last [required] chance for education.
But the whole process, if used, can be a great educational experience.
Learn to fly what you want to fly.

IMHO the low-and-slow cert is for "punch my ticket" people.
It represents a small corner-case of rocketry and really only demonstrates risk avoidance.

 

[sharkbait]

The point of the cert is to denote proficiency in the type of flying that a person will do once certified.

My philosophy is to acquire proficiency in the type of flying that I will do once certified, so that the certification flight itself is just another flight that happens to be demonstrating that proficiency. There is no penalty if something goes wrong that is any different than it would be on any other flight. It's not like I have to pay the prefect a $100 fee every time I say, "This is my cert flight." If I fail to recover the rocket, or it has a non-nominal flight or is damaged otherwise, the penalty in time and treasure is exactly the same as if I was already certified, except that more people will be watching. But with my plan, I will already have flown and recovered the rocket many times, watched the exact deployment hardware and software function at low altitude, etc. So the risk will be very well managed. The point is to be proficient, so that managing the risk is baked into the pie.

The point of the cert isn't the piece of paper, it's getting myself and my program to the point where doing the thing that the piece of paper says I'm qualified to do is not a big deal.

We'll just have to disagree, I guess.

+1
I don’t see the sense in say getting your L1 on a 700’ flight with Loc Warlock then planning to do your next flight with min diameter I-1299

Also agree that you should have some MPR similar flights with DD and MD, and if you happen to fail your L1 flight, you hopefully learn why and correct and hone those points for the next attempt

 

[ksaves2]

I've seen these discussions a lot. My take is that going low and slow is definitely safer and more likely to result in a certification. However, if a flyer goes in to minimum diameter with their eyes open on the risk of failing certification, I don't see why to close the door. It would be a good idea to practice dual deployment on a smaller rocket prior to attempting the certification.

Typical descent speeds under drogue are 80-100 FPS, and 20-25 FPS under main. The latter depends heavily on what kind of terrain you're landing on. Sod is far more forgiving than concrete or dry lakebed. Remember that you need to keep the fins on in order to get your certification.

Retention can also be tape over the back of the airframe and the thrust ring on the motor. I have personally had success with electrical tape pulled tight, and I know I've seen people who have had success with aluminized tape for HVAC ducting. Retention via a bolt forward is probably more secure.

The other question I have to ask is, "How much money does one want to spend?" Saw an L-3 cert flight on an "M" motor and the flier had the
facilities to build a large rocket and used the cheapest electronics of the time. It was in the nineties and a full scale Phoenix Missile. Cert flight was nominal. (MWP 3) Later did a flight on I believe a club mixed "N" motor at the local club site and only two of the three chutes opened. Had butt end damage that took a few years to fix. Flight was cool on the upside and still within sight with the smoke but the "downside" wasn't nominal. Not that it was so bad but the flier had to work for a living like the rest of us and took time to go fix it. Still flew other projects too in the interim.

Finally he fixed it up and went to a Tripoli launch to fly on an "O" motor I helped mix once the club learned to mix. The upside was perfect. Downside was a lawndart. Flier used three of the cheapest deployment altimeters available at the time. Flew'em without a tracker before on the "M", "N" and things were fine. Flew the rocket with the tracker installed without adequate ground testing and "0" yes zero deployment events occurred. Says something about flying three versions of the same altimeter. Thing I will say is they were cheap, the manufacturer didn't test them in Rf energy but they were economical for one to get an L2 if they chose to do it with DD.

Biggest ground whmup! I've ever felt though I've have to qualify I've never been out to Western launches.

The 3 watt GPS dog tracker dorked the altimeters he used and he would have known that with an adequate ground test that would have happened. I started ground testing my rockets with trackers with the alitmeter(s) armed with bare e-matches before that with whatever tracker I was going to use. I acquired my Ham radio General license just before the tragic event but the flier didn't inquire to me about radio stuff and I didn't know he was going to do/fly it. If the prefect would have asked me, I would have related my knowledge to him as I just got my Ham license. I didn't know about the particulars until later after the lawn dart.

I had radio interference with deployment on two flights before the "bad event". Took me awhile to realize but it filtered out it was due to "ungrounded" deployment altimeters later on. I only fly those rockets without trackers period.

Flew one rocket with a low powered tracker and the danged thing still "dorked" an E6B altimeter I built and was proud of. THEN I learned of the interference problem! The E6B is OOP now but if one buys one second hand cheap, don't get them close to an Rf tracker PERIOD!!

I've flown them without trackers and they did fine. The neat thing was I built them from a kit and they worked as long as Rf energy wasn't around!

I've got a few rockets left with them, without trackers and have no reservations about flying them. Just use a motor impulse to keep them out of sight for a minimal amount of time "just in case". Kurt

 

[ksaves2]

OR - to put it another way - USE the cert process and the mentors provided within to gain the proficiency needed for your desired style of flying.
As I've often said - the L3 "gateway to unlimited flying" is also the last [required] chance for education.
But the whole process, if used, can be a great educational experience.
Learn to fly what you want to fly.

IMHO the low-and-slow cert is for "punch my ticket" people.
It represents a small corner-case of rocketry and really only demonstrates risk avoidance.

There's nothing wrong with "punch my ticket people" as one needs to progress sequentially. Get the L1 and then progress with higher L1 flights "like" starting to experiment with DD? If they want to go on to L2 and as long as they pay their dues to NAR or TRA what's the problem? If folks want to achieve a level and stop, what's the issue!

Fred, I think you have "LOST SIGHT" of how much it costs to certify with the so-called "commercial" grains. What's an L2 SU motor or reloadable casing cost these days? Not accounting for the grains for a reloadable case situation. It COSTS ALOT and yes you can say other hobbies cost more but which ones?

I think my J-350 I bought previously cost $49.95 back in the day and I forgot what I paid for the casing. How much do they cost now? Am looking online and some are well over $100.00 for the grains alone. How many working people can afford that now?

How can you diss people who go to L1, L2 or even L3 and stop there? It's an achievement they've made, paid money for and had success and stop for whatever reason. Be it work, family or sending a kid through college what have you!

You are being so "freaking" presumptuous beyond belief it's ridiculous. Amateur rocketry is for fun and what one wants to make of it. You're out in left field though I thought you'd be the last one there actually.

Kurt Savegnago