L2 Kit Recommendation

[Art Upton]

Yeah, I tracked one to a great big gravel pit... not getting that one back.

Yes , I had/have a rocket hangin' in a Tree in the middle of a Bog in TN next to the SOD farm used as the launch field. I really did not see that coming. I caught some different air and it went in a direction I had not anticipated.

Lost a nice 440mhz GPS. Had a nice pic Pointing to it on Google Maps saying "My Rocket Is Here". Several folks including a Scout group tried to get to it in the Bog, but found it too much of a challenge.

 

[jqavins]

I agree with that, but there is also this issue if I did not mention it before.

With a GPS or RDF tracker, you can know exactly where your rocket is, but not be able to get to it*

* Treed for example, or Treed in a Bog/Swamp.

One problem at a time; you can't even try to get it out of that tree unless you know what tree it's in first.

 

[Antares JS]

300 feet is what one flyer after another that I've observed uses, successfully time after time. That's the only reason I have for picking it, and I will certainly take all your comments into consideration.

It depends on the size of the parachute. I've used 300 feet on a 42" parachute, the canopy wasn't open until the last second, and a fin ended up sticking in the ground on landing, popping it off the rocket.

If your parachute is bigger than 36" or so, I would bump it up to 500 feet to give it a little more time to open.

Another thing to possibly note, my experience with LOC parachutes hasn't been 100% good. one 30" parachute of mine from a LOC kit has been known to come out of the rocket, unfurl the shroud lines, and not open due to stiffness after being released by my JLCR.

 

[jqavins]

This is the approximate map of my home club's launch field, where 300' is the norm. The grass is sometime knee high. As you can see, one really does not want that rocket drifting.


This is the area of the field at Potter at the same scale, though I don't know where the flight line is.

If the flight line is in that squareish area next to 364 than it's a bunch smaller. I hope the flight line is in that much bigger area at the top. So my choice of altitude to open will depend on the location and the wind. And advice from others on the field on the day.

 

[ksaves2]

That all sounds like good advice. My plan is pretty well set at the moment.

• I will be flying with the lowest impulse motor that gets me good rail exit speed.
• I will be flying a GPS tracker.
• I will be using a JLCR to unfurl the main at 300 ft.

Please report the success of the flight or if the rocket smacks the ground. I vote for the latter if you don't do some serious test-flying to see if the rocket and recovery system will perform at that low of main deployment. Don't test? It's a crap shoot and might have to build a new rocket to start over to certify if you still have the fortitude to certify.
If you test the rocket/recovery system to make sure it works at such a low main deployment consistently then fine, go for it. Big wow factor! Start at a higher main deployment and work your way down. If it works consistently you're good to go.
If blindly flying it for the first time without testing and it fails, too bad for you. If it works, blind luck. I find the successful certifying flights are those who don't do any fancy stuff on recovery and have tested their rockets with lower impulse engines first. Sure on the cert flight it will fly higher, faster and farther (hopefully not too far) because of the next higher impulse motor used. 300 feet is too low a main deployment for an untested system.
If I was going to do that, I would start with higher main deployments and see how long it takes for the harness to extend and the chute to deploy. The JLCR is generally quick. If the JLCR releases while the harness is still extending and not played out, it can lead to tangling. Believe me, I've attended enough flights to witness that. At 300 feet there isn't enough time for extension of a harness WITHOUT testing. This is a case where too long a harness could be a rocket ending smack the ground episode before the main chute has time to open. Again, I've been around long enough to witness that happen.
Had a few harness proclivities with my own JLCR devices that led to heart stopping "just above the Earth" recoveries that lead to intact rockets but I don't like to see that. Most of the time I was by myself and nobody else saw it.

 

[ksaves2]

This is the approximate map of my home club's launch field, where 300' is the norm. The grass is sometime knee high. As you can see, one really does not want that rocket drifting.
This is the area of the field at Potter at the same scale, though I don't know where the flight line is.
If the flight line is in that squareish area next to 364 than it's a bunch smaller. I hope the flight line is in that much bigger area at the top. So my choice of altitude to open will depend on the location and the wind. And advice from others on the field on the day.

Ummm, You said you were using a GPS tracker. That will negate the grass somewhat so don't worry about that as long as the farmers aren't harvesting. Sometimes the rocket can be spotted as the relatively lighter parachute canopy at least in smaller rockets will sit on top of the tall grass for easier sighting.
That helped with my modrocs in recovering them along with a noise maker on the harness. If the rocket is so small one can't fit an Rf tracker, a noisemaker on the harness can be very helpful. The louder the better though I'm aware of size limitations in smaller rockets. Get the loudest smallest thing you can get!

If you've flown the cert rocket before on lower impulse motors and recovered from 300 feet successfully, I stand corrected. Can't argue when a system has been tested. My rant is about planning and blindly flying expecting that all the simulators in the world will be correct. They're close but rarely the model rocket stuff is spot on. Conditions at a field can vary wildly from what is planned.

500 feet is more reasonable for main deployment given harness issues but if you've walked up to 300 feet successfully in testing, go for it. If not then good luck!

 

[jqavins]

There are mixed opinions on testing before a cert flight. If the recovery fails and the rocket is destroyed, it really doesn't matter whether that was on a cert flight or beforehand. There's no penalty for failing. Test flights are more flights, and therefore more chances for random fecal-turbine interactions. No, a bad choice of chute release altitude is not a random thing, but there have been many a random thing that has spoiled many flight, e.g. motor CATOs. A CATO on a cert flight is no more of a bummer than a CATO on a test flight, and a crash from 300' on a cert flight is no worse than a crash on a test flight, so why risk it? That's the argument against test flights that several people have made, and I buy it.

This is not to say "I'm sticking with 300 ft no matter what." I'll consider it, and look for advice (as I stated above) at the field on the day, when I will have the lay of the land and know what the weather is.

Ummm, You said you were using a GPS tracker. That will negate the grass somewhat so don't worry about that as long as the farmers aren't harvesting. Sometimes the rocket can be spotted as the relatively lighter parachute canopy at least in smaller rockets will sit on top of the tall grass for easier sighting.

Belt and suspenders.

The JLCR is generally quick. If the JLCR releases while the harness is still extending and not played out, it can lead to tangling.

If the harness hasn't fully played out while the rocket is descending from 2000 ft or so to 300 ft, wouldn't you say I've got bigger problems? And doesn't releasing 200 ft higher just make the small chance of that ever so slightly greater?

[A] noisemaker on the harness can be very helpful.

That's a good idea, thanks. Belt, suspenders, and... more suspenders?

 

[Art Upton]

This is the approximate map of my home club's launch field, where 300' is the norm. The grass is sometime knee high. As you can see, one really does not want that rocket drifting.
View attachment 645711

This is the area of the field at Potter at the same scale, though I don't know where the flight line is.
View attachment 645712
If the flight line is in that squareish area next to 364 than it's a bunch smaller. I hope the flight line is in that much bigger area at the top. So my choice of altitude to open will depend on the location and the wind. And advice from others on the field on the day.

Based on the Picture, your Club is MARS at the HAG it looks like. That is where I Popped the I-Roc Chute at the Top on the J285 for my NAR L2 re-cert in 2003. Been there many times.

I've last been there in 2018 at NAR NSL where I flew my I-Roc on a JLCR at 500 setting, My AeroTech 1.8" Arreaux on a H135 Pop at the Top, and later the LOC Caliber ISP 3" rocket on the I65 with the JLCR at 500 setting.

What has changed that you don't want a Chute opening until 250-225 feet which is what a 300 setting will generally give you? Is it just the walking issue or are there new hazards?

On the Small side I have flown a 1.6" paper tube Nike Smoke on a composite D motor with Pop at the Top.
Yes I had to walk for it but it was recoverable.

When I was at Potter last in 2012 for an LDRS, and once before that; it seemed larger then Geneseo. In fact larger and higher rockets get flown at Potter then at Geneseo.

But things change over the years so again maybe there are new hazards.

 

[ksaves2]

If the harness hasn't fully played out while the rocket is descending from 2000 ft or so to 300 ft, wouldn't you say I've got bigger problems? And doesn't releasing 200 ft higher just make the small chance of that ever so slightly greater?

That's a good idea, thanks. Belt, suspenders, and... more suspenders?

Yup, you gotta bigger problem then. But at a higher main deployment altitude there is more time for slow harness deployment to sort out and get a good chute before slamming terra firma. I've seen plenty of fliers including myself who've had higher level main deployments 500 feet plus and unplanned harness issues ensue and the chute deploys just before the rocket smashes in. On a cert flight I'd plan for a more conservative flight to get it out of the way and then go for the different awe inspiring stuff.
More suspenders? I hardly think a higher main deployment is that. It's more like "insurance" to get a nominal main chute before the rocket breaks a fin on the landing to negate the cert flight with a too late deployment.
If you're able to test that is wise. Sure you can lose a rocket on a test but then again, you can lose an untested rocket on a certification flight. Learning curve here?

 

[Art Upton]

This is the approximate map of my home club's launch field, where 300' is the norm. The grass is sometime knee high. As you can see, one really does not want that rocket drifting.
View attachment 645711

This is the area of the field at Potter at the same scale, though I don't know where the flight line is.
View attachment 645712
If the flight line is in that squareish area next to 364 than it's a bunch smaller. I hope the flight line is in that much bigger area at the top. So my choice of altitude to open will depend on the location and the wind. And advice from others on the field on the day.

If I recall correctly this part is the flying field. And the flight line would be the area between the brown and green on the left.

Parking in the brown on the left. But that was some time ago in 2012 and before.

I recall one year they got WoodStock like rains for 3 days. People had parked before the rains and left trailers.
I remember rubber tracked CATs pulling stuff out even when it stopped raining.

There is an elevation difference, the flying field is lower then the entrance area.

 

[jqavins]

Based on the Picture, your Club is MARS at the HAG it looks like. That is where I Popped the I-Roc Chute at the Top on the J285 for my NAR L2 re-cert in 2003. Been there many times.

Yup, MARS. At the National Warplane Museum; what's HAG?

What has changed that you don't want a Chute opening until 250-225 feet which is what a 300 setting will generally give you? Is it just the walking issue or are there new hazards?

Drift distance, which is more about losing it than the long walk to pick it up (not that shorter walks aren't good).

More suspenders? I hardly think a higher main deployment is that.

A noise maker is.

On a cert flight I'd plan for a more conservative flight to get it out of the way and then go for the different awe inspiring stuff... Sure you can lose a rocket on a test but then again, you can lose an untested rocket on a certification flight.

And you can lose a tested rocket on a cert flight. Many of your comments seem to be based on the notion that failing a cert flight is worse than failing a test flight before or another flight after. Why? A failure is a failure; and I can always try again for the cert, just like I'd repair or rebuild and fly again in any other circumstance.

I don't plan to do any daredevil low deployments after the cert any more than I would or will on the cert flight. The question is whether or not 300 feet is a daredevil release altitude. You obviously think it's too low, and you seem to be in the majority, and (for the third time) I'm taking that advice into consideration along with my observations and advice I'll gather at the field.

 

[Art Upton]

Yup, MARS. At the National Warplane Museum; what's HAG?


Drift distance, which is more about losing it than the long walk to pick it up (not that shorter walks aren't good).


A noise maker is.
View attachment 645746


And you can lose a tested rocket on a cert flight. Many of your comments seem to be based on the notion that failing a cert flight is worse than failing a test flight before or another flight after. Why? A failure is a failure; and I can always try again for the cert, just like I'd repair or rebuild and fly again in any other circumstance.

It was originally called the "Historical Aircraft Group" the HAG

 

[loopy]

I don't plan to do any daredevil low deployments after the cert any more than I would or will on the cert flight. The question is whether or not 300 feet is a daredevil release altitude. You obviously think it's too low, and you seem to be in the majority, and (for the third time) I'm taking that advice into consideration along with my observations and advice I'll gather at the field.

My personal opinion, and one shared by most I fly with...if you're flying a 4" rocket, you want to give it plenty of time for the larger 'chute to inflate. 300' is very low for that. The lowest I set mine is 400' (same for my pyro dual deploy rockets), and that's for smaller rockets with smaller 'chutes. It takes time for those bigger 'chutes to inflate and slow the rocket down. With JLCR, your shock cords are already at full length, but it's better to have more room for the 'chute to inflate and slow the rocket down. If you have a tracker and you're not worried about a longer walk, it's cheap insurance to deploy your main a couple hundred feet higher. It's not going to drift that much further. And this isn't just for cert flights vs. shakedown flights, this is every flight.

 

[ksaves2]

Yup, MARS. At the National Warplane Museum; what's HAG?


Drift distance, which is more about losing it than the long walk to pick it up (not that shorter walks aren't good).


A noise maker is.
View attachment 645746


And you can lose a tested rocket on a cert flight. Many of your comments seem to be based on the notion that failing a cert flight is worse than failing a test flight before or another flight after. Why? A failure is a failure; and I can always try again for the cert, just like I'd repair or rebuild and fly again in any other circumstance.

I don't plan to do any daredevil low deployments after the cert any more than I would or will on the cert flight. The question is whether or not 300 feet is a daredevil release altitude. You obviously think it's too low, and you seem to be in the majority, and (for the third time) I'm taking that advice into consideration along with my observations and advice I'll gather at the field.

Weeeelllllll if one wants to have a successful cert flight, I'm convinced sequential testing will improve ones chances to have a success. Plus there is knowledge gained by testing. I blew both the L1 and L2 cert flights because of lack of testing and availability of mentors. I tested my L2 rocket after the failure and got it dialed in. The actual cert flight was extremely nominal with DD electronics.

If one "blindly" certs not knowing what they are doing and is successful, they'll be just as ignorant as before. I've witnessed plenty of fliers who certed and on the next flight with the same rocket, an anomaly occurs that causes irreparable damage. I've seen cautious fliers who tested, certed and follow on flights were successful. Yeah, there's a learning curve.

 

[jqavins]

Here's the last thing I'll say about test flights, because I really don't want this to become an argument. For your L2 cert effort, you made at least three flights: a failed cert, at least one test (the post above didn't say how many) and the successful cert. You could have made the same (at least three) flights, calling the first one a test, and got the cert without having a failed attempt. What difference would that have made?

Of course there's a learning curve. The whole hobby is about learning, from others and from one's own mistakes. If I learn from a failed cert or I learn from a failed test, to me it's exactly the same thing.

 

[jqavins]

The kit arrived on Thursday, and today I began building. I will start a build thread, and stop following this one.

 

[Rob Campbell]

The kit arrived on Thursday, and today I began building. I will start a build thread, and stop following this one.

Good luck with the build and cert flight.

 

[ksaves2]

Good luck with the build and cert flight.

Yeah, I built an L2 cert rocket that could take L1 motors AFTER I had an L2 cert failure/destruction. Tested the new rocket on lower impulse motors then had a successful certification flight after testing. A simple single J350 motor deploy. Doing cert flights? KISS it. Keep It Simple Stupid. J350 single motor deploy has I believe gotten more L1's to L2 than anything. Do the "funky" electronic stuff once the cert is in the bag.

Once I got the L2 in the bag I really didn't fly any J's for a couple of years. Did an old Loki "Jeff" 54mm L motor in a longed necked rocket just because I could after L2 certing. It went to 10k/supersonic in a 54mm motored version of a Wildman rocket I stretched it to a longnecked version. I was surprised as I stretched the length of the rocket, didn't change the fin size that Tim sent with the kit and it flew straight and true.
Something to say about getting a rocket to high velocity fast! That rocket is still flyable. Oh first flight the APRS/GPS tracker didn't work. I did a rapid ground test but the rocket was entirely painted in metallic paint. Metallic paint "shields" Rf energy in and out. I didn't know that at the time. Fortunately it landed within sight and the dual deployment worked nominally.

I did buy a new nosecone from Tim a zillion years ago to put the tracker in the nosecone and retire the older nosecone to another project. I found out on that rocket that metallic paints don't allow Rf out from the inside. Man o' man I was glad I was able to figure that out before trying to fly and eventually remedied that by painting rockets with metallic paint BUT painting the nosecone tracker WITH NON-METALLIC PAINT!! PEOPLE don't make the mistake I made in my "early days".

DO NOT, I REPEAT DO NOT paint a tracker bay or where the antenna "will be" with metallic paint! I found out the hard way. I haven't tested it with the 900Mhz stuff but after being dorked so many times I don't want to repeat past failures.

Oh after the L2 cert I actually flew a pile of "I" and under motor impulse motors with electronics, single and dual deploy. Essentially L1 motors. Learned electronics that way. Did a "J" every now and then but did more J and L's once I learned mixing with a group and went to the Research launches of the time.

Shoot, I have a 2 grain 38mm mixed motor for an AT case that kicks butt. Uses a Garolite liner and gets off the pad fast more than a commercial AT H-130.
Much cheaper too as long as one mixes long enough to write off start up costs.

The erosive phenolic nozzles gives one some leeway with firing. The larger motors with graphite nozzles have little leeway as graphite doesn't erode much.
My ground failures occurred with overpressurizations with a too narrow of a graphite nozzle throat.

In my AT stuff/hardware I have to give it to AT they post all the specifics and details on their motors/hardware/nozzles/o rings and such. I can put my mixed propellants in their cases easily using their parameters.

If a case of theirs blows with my propellant in it, it's my problem. Never have complained and simply order new hardware from whatever concern I'm dealing with. Yeah I don't complain even if I've run a case with my propellant and then it blows with an AT load in it. Research mixes can stress stuff to beyond what the commercial mixers make. Though I had AT case failures when I just ran their commercial loads through. I think reloadable cases might last 10 to 15 firings and would like to see more opinions on that.

The so called "amateur" turned casings the prefect I associated with who had a giant metal lathe are thicker and more robust. Shoot he had a couple of lathes for turning metal casings and one he would take outside the shop to turn graphite nozzles. The graphite powder was a PITA to deal with and better to turn outside the shop. Deal was getting a system with liners and casting tubes to fit an Al tubing system.

54mm casing was the worst to machine the prefect said. Scott Kormeier now from Loki said the same thing when he visited our prefecture during a research mix before he took over Loki Rocketry from Dr. Jeff Taylor a long time ago. Worked for Dr. Taylor for a time then bought Loki from him.

Oh, I forgot to mention on my 2 grained 38mm AT mixed motor clone I have to use a nozzle for an AT J-350 and drill it out a "little bit"!
That's what the sim said and I titrated it from there. Beats an H-130 every time.