Requesting L2 rocket advice

[Arsenal78]

Fiberglass can be used for L2 but imo if you've never done a fiberglass rocket, that should be a bridge you cross when a cert isn't up in the air, kinda like doing your L3 and it being your first dual deployment flight. Use a simple rocket with a simple DMS motor and it'll be golden. Fiberglass rockets require a few different techniques to building them and it's something you shouldn't really do if a cert is riding on it.

Also that Apogee Level 2 rocket says the weight is about 8lbs which is the same as the Goblin but with less drag and about $200 more so while the weight is the same, it will go higher.

 

[g.pitts]

I thank all of you for your supportive comments regarding fiberglass. I am taking everything to heart, I assure you.

Two specific questions regarding the Apogee Components L2 rocket, please:

• It does not require dual deployment, does it?
• Apparently it does not have pre-made for the fins, right?

Stanley

Hello Stanley, I was certified on my L1 and L2 using this kit. It’s a tank! Very solid and rugged. My kit came with a slotted body tube for the fins, but the fins were not beveled. The kit can be built for either single or dual deployment. Hope this helps!

 

[mtnmanak]

I thank all of you for your supportive comments regarding fiberglass. I am taking everything to heart, I assure you.

Two specific questions regarding the Apogee Components L2 rocket, please:

• It does not require dual deployment, does it?
• Apparently it does not have pre-made for the fins, right?

Stanley

You don't have to fly it dual deploy. In most "standard" dual deploy scenarios, the nosecone is held on by nylon shear pins (in the case of this rocket, the "shear pin" is nothing more than a 2-56 threaded 1/4" nylon screw - very cheap and easy to get). The easiest way to fly the rocket via motor ejection is to use metal screws instead of nylon screws (this is easier than it sounds and the Apogee build video walks you through how to install the pins) and to not use a flight computer. The main parachute will just deploy normally from the booster tube upon motor ejection.

I do recommend trying dual deploy out, though. Once you do, you will never go back.

As far as the fins go, the tube is preslotted and the fins are not beveled. Easy day - install the fins through the slots and epoxy the snot out of the internal fillets. Do not bevel the fins - you want as much drag as you can get.

Also that Apogee Level 2 rocket says the weight is about 8lbs which is the same as the Goblin but with less drag and about $200 more so while the weight is the same, it will go higher.

I may have built my Level 2 heavy, but the lightest pad weight I have ever had was 10 pounds on an I599. I think the weight they quote on the Apogee site may be without all the components like shock cords, ebay, etc. Epoxy alone will probably add a significant amount of weight. I also built out my nosecone with a bulkhead, U-bolt and removable bay.

As with any rocket, you should always build a new Rocksim file from scratch with the exact parts you get in your kit and all the things you add. Ideally, if you do it right, your dry and loaded weights and CG measurements should be very close to the ones you see in Rocksim. This is the only way to get accurate results from the sim. If I use the generic Level 2 Rocksim file, the rocket sims out to 1100 feet on an I599 and 2400 feet on a J250. The sim from my file and my build shows those motors to fly my bird to 850 feet on an I599 and 1800 feet on a J250, which is almost exactly what I have seen in real world launches.

One thing I would say here is that, honestly, you can build any of the rockets mentioned here and have a great Level 2 cert flight. 90% of your success won't be the rocket you choose, it will be your attention to detail and care in the build process and and your attention to detail during the pre-flight on the day of your launch. If you do all that well, you can shove a J into any rocket that will take one and have a very good chance of success.

Honestly, when I showed up to launch day for my Level 2 cert, I had built 3 rockets capable of flying a J engine comfortably and had 3 J250 motors with me. I ended up flying them all that day, dual deploy and all 3 of them were successful. I brought 3 because I figured at least ONE of them would work

 

[mtnmanak]

Fiberglass can be used for L2 but imo if you've never done a fiberglass rocket, that should be a bridge you cross when a cert isn't up in the air, kinda like doing your L3 and it being your first dual deployment flight. Use a simple rocket with a simple DMS motor and it'll be golden. Fiberglass rockets require a few different techniques to building them and it's something you shouldn't really do if a cert is riding on it.

While I agree with this to a certain extent, I think everyone is jumping to the conclusion that the maiden flight of the rocket will/should be the cert flight. The nice thing about having your Level 1 cert is that you have access to an awesome array of high power motors that will fly many/most level 2 birds with no problem. Build 10 fiberglass rockets and fly them on I motors all day. Build them all dual deploy and fly them on I motors until your money runs out.

If you want a great rocket that will last a long time and take you way beyond your cert, jump in, build an easy FG rocket with dual deploy and fly it on I motors until you get tired of it. Then, when you fly for your cert, you aren't doing anything new - just upping the impulse.

Anyone that builds out a rocket and just goes to the field and flies it for the first time as a cert flight for Level 2 is asking for trouble. Especially since there is no reason to do that. There is no race or competition to Level 2 that I am aware of. Building out a big dual deploy FG rocket is just plain fun! Have fun, take your time, test fly it a lot, and enjoy the whole process.

 

[Dan Griffing]

Apogee Level 2 rocket says the weight is about 8lbs ...

My L2 rocket was an Apogee Zephyr. The kit cost $93.46, excluding shipping, and was complete with all the necessary parts for an L1 launch but the motor retainer.

I built it heavily for my L1 launch, and modified it for my L2 certification by adding dual deployment with a $35 Apogee Electronics Bay kit and a $7 18” upper main parachute bay airframe section, two 25’ Kevlar shock cord harnesses, and main, and drogue parachutes. The E-bay also contained the additional weight of a GPS tracker, dual deployment flight computer, and LiPo batteries.

With all of this weight, and an Aerotech DMS J270W motor, my notes recorded that the launch weight of this dual deployment-modified L2 Apogee Zephyr was only 8.24 lbs.

 

[Dan Griffing]

kinda like doing your L3 and it being your first dual deployment flight.

Against all sage advice, I did this very thing, dual deployment, for my L2 cert.

My reason was that since I was pushing my L2 shortly after getting my L1, I wanted to use the dual deployment to demonstrate that my mastery of advanced techniques made me worthy of advancing so quickly.

I figured that—as a retired engineer who had executed many more difficult technical, critical, and complex projects throughout my career—if I wasn’t ready to use dual deployment in my L2 attempt, then I wasn’t ready for advancing to L2.

You have the “right stuff” when you can hang it all out there, and then bring it back down safely and undamaged.

 

[Five]

What does this even mean? Are you saying that you have a sanctioned group project at work to help you study for a model rocketry exam?

"Work" has apparently taken on a new meaning of which I am not familiar!

SMH

 

[Five]

How many of you follow this forum while at "work"?

Zeke

I do. Especially for the last couple hours of the work day which is overtime...
Im sorry if that offends you. It was never my intention.

 

[ghuber]

In coming back to the "low and slow" and not fiberglass, I would also plug a scratch built tube fin. My L2 was built from 5.38" LOC tubing, 60" tall, plus a coupler and a nose cone. Each 34" of 5.38" tubing is $37.50, so you can buy 3 (2 for body, 1 to cut 6 fins a a bit for the coupler), a coupler is $10, and the nose cone was $65. I cut bulkheads and a thrust ring from 1/4" plywood and used a 60" chute. It simmed to approx. 2K feet on a J250 and I used a JR chute release. Motor tubing was 54mm, but I've also built adapters for 38mm, and if you take off the top half of the rocket you can fly the "stubby" with a bit of added nose weight.

On a subsequent launch in stubby form I had a thrust ring on a DMS motor let go during powered thrust and the motor ejected through the body of the tube, frying the chute. It fell from approx. 600 feet and totaled one of the fins, but we just cut a new fin off the existing top section and replaced the busted one. (cutting out the damaged fin was only hard because epoxy is difficult to cut).

 

[MetricRocketeer]

Hi ghuber,

Thank you for the drawing.

I don't know if I will go that route, but I will try to draw and fly it in RockSim.

Stanley

 

[MetricRocketeer]

Hi ghuber,

Please don't feel obligated to spend time on my next question if you don't want. Whatever I do, I will buy a kit.

However, because I am always trying to improve my skills, I have started to draw your rocket design using RockSim.

I am a bit stymied on what I should do with the fins. I chose Apogee Part No. 15693 "Clipped Delta Plywood" just because I liked the shape. Was that a good choice? Also, what dimensions should I use for the fins? Just using what came up with the dimensions of the two tubes makes the fins seem too small. And should I use three or four fins?

I would appreciate your input, or anyone's input. But it is purely academic, because I will purchase a kit.

Thank you for your consideration.

Stanley

 

[thzero]

Maybe you should build some intermediary rockets and experiment? Why rush to get the level 2?

Kits have all sorts of fin designs... generally you need to have 1 caliber between CG and CP, and CG ahead of CP. 3 fins have less drag, 4 fins have more, but may achieve better stability. More fins have generally mean the CP moves aftwards, but it also depends on where the fins are in the airstream.

Good reading would be Harry G Stines book, and High Power Rocketry.

 

[boatgeek]

An important question--how high is the FAA waiver at the site you plant to fly, and how big is the field? Have you gotten any advice from a local club about how high you can reasonably fly on the field? Experienced club members can probably tell you that you can reasonably safely fly to X feet single deploy and Y feet dual deploy at your field and still get the rocket back. That will give you some guardrails as you choose a design.

If you are lucky enough to fly in wide open spaces with high waivers, here's a couple of rules of thumb for keeping rockets in sight: 4", no more than 5-6,000'. 3", no more than 3,500'. That's for reasonable visibility conditions by someone with reasonable eyesight. Adjust up and down as needed to suit your conditions/eyesight.

 

[ghuber]

I don't use RockSim, but the attached OpenRocket file has the entire design mocked up. OpenRocket has a TubeFin option.

There are some great build guides on this forum for L1, L2, and L3 Tube fins. I fly a lot of low power tube fins also because they are easy to build with kids.

https://apogeerockets.com/education/downloads/Newsletter335.pdf

 

[Dan Griffing]

I'm not trying to pick a fight, but

When you start a reply this way, its difficult to see how you are doing anything else but trying to pick a fight while denying it.

 

[Dan Griffing]

You don't have to fly it dual deploy. In most "standard" dual deploy scenarios, the nosecone is held on by nylon shear pins (in the case of this rocket, the "shear pin" is nothing more than a 2-56 threaded 1/4" nylon screw - very cheap and easy to get). The easiest way to fly the rocket via motor ejection is to use metal screws instead of nylon screws (this is easier than it sounds and the Apogee build video walks you through how to install the pins) and to not use a flight computer. The main parachute will just deploy normally from the booster tube upon motor ejection.

I do recommend trying dual deploy out, though. Once you do, you will never go back.

As far as the fins go, the tube is preslotted and the fins are not beveled. Easy day - install the fins through the slots and epoxy the snot out of the internal fillets. Do not bevel the fins - you want as much drag as you can get.



I may have built my Level 2 heavy, but the lightest pad weight I have ever had was 10 pounds on an I599. I think the weight they quote on the Apogee site may be without all the components like shock cords, ebay, etc. Epoxy alone will probably add a significant amount of weight. I also built out my nosecone with a bulkhead, U-bolt and removable bay.

As with any rocket, you should always build a new Rocksim file from scratch with the exact parts you get in your kit and all the things you add. Ideally, if you do it right, your dry and loaded weights and CG measurements should be very close to the ones you see in Rocksim. This is the only way to get accurate results from the sim. If I use the generic Level 2 Rocksim file, the rocket sims out to 1100 feet on an I599 and 2400 feet on a J250. The sim from my file and my build shows those motors to fly my bird to 850 feet on an I599 and 1800 feet on a J250, which is almost exactly what I have seen in real world launches.

One thing I would say here is that, honestly, you can build any of the rockets mentioned here and have a great Level 2 cert flight. 90% of your success won't be the rocket you choose, it will be your attention to detail and care in the build process and and your attention to detail during the pre-flight on the day of your launch. If you do all that well, you can shove a J into any rocket that will take one and have a very good chance of success.

Honestly, when I showed up to launch day for my Level 2 cert, I had built 3 rockets capable of flying a J engine comfortably and had 3 J250 motors with me. I ended up flying them all that day, dual deploy and all 3 of them were successful. I brought 3 because I figured at least ONE of them would work

What a great post!

Looking at a L2 cert beforehand, it looks like a huge mountain to climb. But in retrospect, the preparations and the journey are more important than the actual destination.

Once I got my L2 it became clear that L2 motors are twice as expensive as L1 motors. Now with my L2 behind me, I can relax while enjoying and learning a lot from less expensive L1 launches.

 

[thzero]

Or even midpower Gs are no slouch depending on what you are launching!

Once I got my L2 it became clear that L2 motors are twice as expensive as L1 motors. Now with my L2 behind me, I can relax while enjoying and learning a lot from less expensive L1 launches.

 

[Arsenal78]

What a great post!

Looking at a L2 cert beforehand, it looks like a huge mountain to climb. But in retrospect, the preparations and the journey are more important than the actual destination.

Once I got my L2 it became clear that L2 motors are twice as expensive as L1 motors. Now with my L2 behind me, I can relax while enjoying and learning a lot from less expensive L1 launches.

I just got my L2 back in November and while I will fly a K at our yearly big launch, I'll have more fun with G-I motors to learn other things on.

 

[rocketman328]

You must not be worried about the written exam I assume. Ill be taking a shot at the L2 cert at springfest and the exam is what kinda scares me. Most of the questions I’m familiar with but I’ve also been studying everyday at work and will continue to study and get paid while doing it....
Wish you Good luck on your level 2

So, are you studying to pass the test or understand the material?

 

[Dan Griffing]

So, are you studying to pass the test or understand the material?

Since the NAR online L2 study guide is the set of questions from which a subset is selected for the test, the overwhelming temptation is to study for the test primarily.

Its the same problem with teachers drilling their students with the questions used in the tests they will be taking. Its an unfortunate consequence of the need to pass tests, or of teachers being graded on how many of their students pass tests.

Hopefully some material will be learned in the process as well.

 

[tomsteve]

i go a little different:
LOC mini magg with 54mmt upgrade, an extra section of BT,coupler, and bulk plate to extend it.
it flies great as a stubby on a J90.

 

[MetricRocketeer]

Hi tomsteve,

But I already have a 38 mm motor-mount tube in it. Is it possible to upgrade to a 54 mm? I know you can go down, but how can you go up?

Stanley

 

[Bowman]

When you start a reply this way, its difficult to see how you are doing anything else but trying to pick a fight while denying it.

Well that is not the case.
I was simply trying to point-out that a persons boss Might not be in-favor of an employee working on personal projects.
If the OP is young or new to the workforce, they may not have considered that.

But statements are all subject to interpretation. Especially in written form.
But I do thank you for calling-out how it appeared to you.
I'll be sure to consider that in future posts.

 

[Hobie1dog]

Stanley: What kit are you going to buy, after 3 pages of people trying to sway you to build the rocket they did?

 

[MetricRocketeer]

Hi everyone,

I spent most of the day attending the virtual NARCON 2021, whose Friday session ended a few minutes ago.

I want to sincerely thank everyone for their tremendous help in making me understand the issues involved in choosing a rocket for an L2-certification flight.

I think that I have decided upon the LOC/Precision 5.5 Goblin.

Stanley

 

[Nytrunner]

I think that I have decided upon the LOC/Precision 5.5 Goblin.

It's a solid rocket by many accounts. I think you'll enjoy it

 

[Dan Griffing]

I was simply trying to point-out that a persons boss Might not be in-favor of an employee working on personal projects.

I worked as an engineer in Silicon Valley for 15 years and for high tech employers for the remainder of my forty-year career.

Most employers don’t mind employees who spend their private time working on company matters — so they shouldn’t mind either when employees spend some time at work on personal matters. Furthermore, so much office time is wasted with inter-office schmoozing, coffee room gossip, and long lunch breaks — that I’m surprised that anyone is acting like a “goody two shoes”, company computer “hall monitor”.

Many employees work from home with the same computer where they have both their work and home accounts, data, and email. When working at home there’s always a blur between private time and company time. Most managers realize that as long as the work gets done, it doesn’t matter if some time gets spent on other things. After all, we aren’t galley slaves chained to our oars with an overseer above us cracking a frigging whip.

Overall, this sanctimonious attitude seems so uncharacteristic of high power rocketeers in general.

 

[Buckeye]

— so they shouldn’t mind either when employees spend some time at work on personal matters.

You are missing the point. Go back and read Mr. Five's posts. He is flaunting his personal time at work, and emphasizing his pay, in some bizarre attempt to impress. Or, he is just trolling.

 

[Dan Griffing]

Oh pulleeze!

You are missing the point. Go back and read Mr. Five's posts. He is flaunting his personal time at work, and emphasizing his pay, in some bizarre attempt to impress. Or, he is just trolling.

Oh pulleeze!

If commenting about the morality of our last president is off limits, let’s focus on building rockets instead of guilt-shaming someone when we don’t really know the relevant details.

In decades past I’ve had the permission to do some things at work with some of my hobbies but didn’t go into those details when I was describing them to others.

The better part of valor is knowing when to mind your own business.

 

[Five]

You are missing the point. Go back and read Mr. Five's posts. He is flaunting his personal time at work, and emphasizing his pay, in some bizarre attempt to impress. Or, he is just trolling.

Im pretty sure this thread was about level 2 advice. With having the same goal I was wondering how confident the creator of the thread felt about the written exam part of the certification.
Wherever i decide to study for the exam is my business. I did not expect people would have problem with where, how, and when i study.
Once again good luck to you metricrocketeer on you cert.