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Requesting L2 rocket advice

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Bowman

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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....
I'm not trying to pick a fight, but unless the L2 somehow fits into your job description, do you think that is ethical?
If it does fit into your job description you are a lucky dog!
My perspective is that of a retired engineering manager used to dealing with tough project deadlines.
 

Donnager

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It looks like both the Goblin and Doorknob include interchangeable motor mounts but the Doorknob also has the adjustable nose weight system. That plus the slightly more complicated paint scheme could account for the difference in skill ratings.
I'm sure the doorknob requires more effort in the nose weight department. That very well may be the case.
 

Five

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I'm not trying to pick a fight, but unless the L2 somehow fits into your job description, do you think that is ethical?
If it does fit into your job description you are a lucky dog!
My perspective is that of a retired engineering manager used to dealing with tough project deadlines.
The job doesn’t have anything to do with the written exam. Fortunately studying while I’m at work will benefit me in more ways than studying on my own.
 

Bowman

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The job doesn’t have anything to do with the written exam. Fortunately studying while I’m at work will benefit me in more ways than studying on my own.
Nice.
Now if they have a decent workshop there you are in great shape.
And has been stated previously, the written exam is nothing to worry about.
It really just solidifies the fundamentals that you need to understand anyways.
 

Buckeye

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Fortunately studying while I’m at work will benefit me in more ways than studying on my own.
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!
 

T-Rex

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My L2 attempt will be flown using a modified LOC Warlock. Similar to the Door Knob but with only 3 fins. Just because you are using a larger kit for a cert flight does not mean it has to be more complicated. I could have built mine stock and it would have been no different from an Estes kit with exception of the size.
Mine was modified was to increase drag to keep it under 2000ft (the top of our waiver), and to make it "mine"
 

Scott_650

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My L2 attempt will be flown using a modified LOC Warlock. Similar to the Door Knob but with only 3 fins. Just because you are using a larger kit for a cert flight does not mean it has to be more complicated. I could have built mine stock and it would have been no different from an Estes kit with exception of the size.
Mine was modified was to increase drag to keep it under 2000ft (the top of our waiver), and to make it "mine"
Curious, what mods did you make to increase drag?
 

T-Rex

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Curious, what mods did you make to increase drag?
I increased the size of the fins. They are also not as rounded as some of my peers think they should be.
Also the parachute that I am using is heavy. While that does not increase drag, it does help to decrease achieved altitude (and helps with CG/CP)
 

thzero

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Square fin edges instead of rounding or airfoil will help increase drag.
 

Dan Griffing

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I reused my L1 cert Apogee Zephyr rocket for my L2 cert with a J270W motor. This saved time and expense for my L2 over building a whole second rocket. I’m not recommending this for everyone because there are considerable benefits to having years of experience and multiple rockets between L1 and L2 certifications.

(Unlike the requirements set out for this thread), I added the Apogee Dual Deployment kit to my Zephyr which made it the approximate equivalent of Apogee’s Peregrine Rocket but with Zephyr fins.

I used Eggtimer GPS electronics for tracking and a 6-channel Eggfinder Proton flight computer for redundant drogue and main ejection charges. The overall loaded weight for my L2 rocket was 8.25 lbs and it reached a modest altitude of 3,200 feet according Jolly Logic’ Altimeter3. The drogue cute I used was Dino Chutes’ 18” X-Form while the main was Fruity Chutes’ 48” toroidal Iris Ultra.

In retrospect, the biggest challenge for using dual deployment was learning how to configure and pack the BP ejection charges and pack the parachutes, flame protection, and Kevlar shock cords.

I used nearly a dozen ground tests for both the drogue and main cutes combined using a stepladder and a “hanging rocket” configuration, and capturing each test with slow motion iPhone video for analysis. Fortunately, the Eggfinder Proton’s Wifi interface to my cell phone made wireless remote testing trivially simple. The benefit of extensive ground testing learning from making the mistakes on the ground instead of at a launch where the cost of a failed deployment would have been the loss of a rocket.

The main benefit of dual deployment was rapidly descending from the 3,200 apogee at 47fps under the drogue, and then opening the main at 800 feet, and gently landing the rocket at 15fps. The rocket landed less than 300 yards from the launch point, so recovery was easy to achieve.

There are significant complexities to successfully using dual deployment. But L2 motors provide the real potential for achieving altitudes where opening the main at apogee could result in the rocket landing miles away and getting lost.
 
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HHaase

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I'm sure the doorknob requires more effort in the nose weight department. That very well may be the case.
The doorknob has both the modular motor mount and modular nose weight system which aren't terribly hard, but do have a learning curve to them.

The Goblin has a standard 54mm motor mount and standard nose cone so it is a more straight forward build.

-Hans
 

Conway Stevens

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Hi cbrarick,

Thank you for your suggestion.

I am reluctant to sand fiberglass, although I know that it is a stronger substance than paper. Perhaps if I am unfortunate enough to crash and destroy my paper-made rocket, I will regret this decision. Nevertheless, as I understand it, sanding fiberglass could be bad for one's health without a very proper ventilation system.

But I do appreciate your input.

Stanley
I'm curious your reluctance to sand fiberglass tube? Actually you won't do much sanding at all quite very minimum and it's not like dealing with what your expecting. I have gotten to where I use 90% glass airframes. They actually require almost no sanding. The finish on them is superb. I only sand where I want my epoxy to bond. Much much stronger at close to the same weight as cardboard. I've got glass rockets that have been flying for 20 years. On big aggressive motors little harder landings. You also might find a 4 inch diameter on the right motor can be plenty low and slow. but they make glass rockets in larger sizes to up to 8 inches and larger.
 

afadeev

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I am reluctant to sand fiberglass, although I know that it is a stronger substance than paper. Perhaps if I am unfortunate enough to crash and destroy my paper-made rocket, I will regret this decision. Nevertheless, as I understand it, sanding fiberglass could be bad for one's health without a very proper ventilation system.
Sanding fiberglass and snorting the dust should definitely be avoided. Same for sanding in bed, or at the dinner table.

Otherwise, I deal with fiberglass dust the same as you deal with primer sanding dust and paint fumes - avoid inhaling all of the above, whenever possible. Wear (any) mask when working indoors, cleanup the residue, work outside (if weather allows), or inside in a well ventilated and "dirty" part of the work shop.

Don't panic, don't over-react, and don't be afraid of fiberglass and CF.
They are great materials that will expand the universe of cool, durable and high-performing rockets that you will be building in the future!

Whatever you choose to build - have fun with it!
You can see a large (4+") diameter airframe upto 3-4K feet with a naked eye, easily. No need to stay under 2K feet.

YMMV,
 
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MetricRocketeer

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I'm curious your reluctance to sand fiberglass tube? Actually you won't do much sanding at all quite very minimum and it's not like dealing with what your expecting. I have gotten to where I use 90% glass airframes. They actually require almost no sanding. The finish on them is superb. I only sand where I want my epoxy to bond. Much much stronger at close to the same weight as cardboard. I've got glass rockets that have been flying for 20 years. On big aggressive motors little harder landings. You also might find a 4 inch diameter on the right motor can be plenty low and slow. but they make glass rockets in larger sizes to up to 8 inches and larger.
Hi Conway,

Thank you for your reply.

Then what would be an easy-to-build fiberglass rocket? I really do want to go "low, slow, and pass" and for my L2 attempt I don't want to do dual-deployment.

Thank you.

Stanley
 

thzero

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Pretty much any of the kits. But really, sounds like maybe you should build some mid-power rockets, some more h and i rockets, get more experience with different materials, sizes and shapes of rockets, then go for the level 2.

Hi Conway,

Thank you for your reply.

Then what would be an easy-to-build fiberglass rocket? I really do want to go "low, slow, and pass" and for my L2 attempt I don't want to do dual-deployment.

Thank you.

Stanley
 

MetricRocketeer

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Hi everyone,

Here is what concerns me about fiberglass. I am quoting a page from the Apogee Components website, where Tim writes about a certain rocket:

"Since it is fiberglass, you need to take health and safety precautions to prevent the fibers of glass from getting into your lungs. A particle mask and disposable gloves are a minimum precaution to take when building the rocket."

Of course, if I didn't have to do any sanding, that would solve the issue of the particles. And not having to worry about zippering my rocket would also be nice.

If I were to go the fiberglass route, I would really want to get a rocket requiring little or no sanding.

I definitely want to go for L2.

Stanley
 

Conway Stevens

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Hi everyone,

Here is what concerns me about fiberglass. I am quoting a page from the Apogee Components website, where Tim writes about a certain rocket:

"Since it is fiberglass, you need to take health and safety precautions to prevent the fibers of glass from getting into your lungs. A particle mask and disposable gloves are a minimum precaution to take when building the rocket."

Of course, if I didn't have to do any sanding, that would solve the issue of the particles. And not having to worry about zippering my rocket would also be nice.

If I were to go the fiberglass route, I would really want to get a rocket requiring little or no sanding.

I definitely want to go for L2.

Stanley
I think the post on Apogee is a little over stated. You should protect yourself from any foreign particles. And compared to other materials you will do so little sanding. Just have common sense.

Look at rockets from Wildman Rocketry. Madcow Rocketry. I would also recommended Mach1 but currently they are changing ownerships and moving so not taking new orders. Hawk mountain is another. But if I had to chose a favorite. Wildman would be it.






These would be great kits for low and slow that are real work horses
 

Wally Ferrer

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The 4" Goblin is what I used for my level 2 on a J425. The 5.5 will definitely fly slower/lower though.

I'd look for almost any 4" fiberglass rocket or a decent sized draggy 4" cardboard rocket.

I don't understand the expert rating on the Doorknob, other than size, but it looks like all the information on that rocket is incomplete (No MMT listed, etc.).
What altitude did you get on that J425? I'm considering using my 4' Goblin for my L2, got my L1 with it...
 

mtnmanak

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Hi everyone,

Here is what concerns me about fiberglass. I am quoting a page from the Apogee Components website, where Tim writes about a certain rocket:

"Since it is fiberglass, you need to take health and safety precautions to prevent the fibers of glass from getting into your lungs. A particle mask and disposable gloves are a minimum precaution to take when building the rocket."

Of course, if I didn't have to do any sanding, that would solve the issue of the particles. And not having to worry about zippering my rocket would also be nice.

If I were to go the fiberglass route, I would really want to get a rocket requiring little or no sanding.

I definitely want to go for L2.

Stanley

I would not worry about the fiberglass so much - I think it is way easier to work with than cardboard.

First thing you need to do is wash all your FG parts - easy to do in a mud sink, outside with a garden hose or (since it is winter), just wash all your parts in the bathtub. For this part, the only PPE you "need" is kitchen rubber gloves (the kind that go up your forearm a bit). Main protection concern is that the edges can be a bit sharp and the rubber gloves do a nice job protecting your arms while you are shoving your hand inside the tube. Nothing special on the soap - plain dishwashing soap works fine. The FG has mold release agents on it (stuff they spray on a mold to keep the FG from sticking to it) and you want to wash that off. It can hinder epoxy adhesion.

It probably is not a bad idea to lightly sand your parts, but you don't need to. As was noted earlier, the only real vital sanding is to rough up any areas you are going to have epoxy adhere to. You don't need to pull out the belt sander here - just some 100 grit on a block or just the sandpaper, rough up the surface a bit. You don't need full HAZMAT gear. Any mask will work fine for light sanding - you should have a bunch around for COVID anyway and wear some nitrile gloves to protect your hands. I sand over some paper towels and then just wrap up any dust and throw the paper towels out. Now that I think about it, the same PPE precautions you take for COVID should work fine for an FG kit.

Later, if you are scratch building and cutting, heavy sanding, CNCing, etc FG or CF, you should take much more stringent precautions, but the parts that come from a kit are 90% ready to go once you wash them, so you shouldn't need to worry about that now. Save that for your Level 3!

Honestly, I think the best kit out there for an L2 cert is the Level 2 from Apogee. It is basically a Madcow Nike Smoke with a payload bay added and an Ogive nosecone subbed in for the Nike Smoke nosecone (you don't want to deal with a Nike Smoke right now, the nosecone that comes with that kit will require you to use standoffs on the rail buttons). The Level 2 rocket from Apogee literally comes with everything you need in the kit except electronics. If you don't want to use Dual Deploy on your cert, just fly it single deploy. However, the nice thing about a rocket like the Level 2 is you can fly the snot out of it on Level 1 motors to test it out and really get comfortable with Dual Deploy. The Level 2 on an I599 only goes to 1000 feet and really blasts it off the pad - great motor to learn your Level 2 on. If you fly it a bunch of times on an I motor with dual deploy, you will get really comfortable with it and, when you finally fly that J, it will just be another launch, not a nail biting event.

After that, the Level 2 scales up nicely. I have built a lot of bigger and heavier rockets, but I still love pulling that Level 2 out sometimes and letting her rip. I flew mine down at MDRA in December on a K690 to 8000 feet at just under Mach 1 and it came back to me in fine fashion.

Frankly, it is probably the easiest 4-fins-and-a-nosecone FG rocket out there. It really is dirt simple to build. And rock solid.

I did a build thread on it here: https://www.rocketryforum.com/threads/apogee-level-2-build.162403/ which includes some videos of the launches.
 
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hobie1dog

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Here is what concerns me about fiberglass. I am quoting a page from the Apogee Components website, where Tim writes about a certain rocket:
"Since it is fiberglass, you need to take health and safety precautions to prevent the fibers of glass from getting into your lungs. A particle mask and disposable gloves are a minimum precaution to take when building the rocket."
Of course, if I didn't have to do any sanding, that would solve the issue of the particles. And not having to worry about zippering my rocket would also be nice.

If I were to go the fiberglass route, I would really want to get a rocket requiring little or no sanding.
Stanley
Stanley: That statement was made concerning building the "Level-2" rocket that they sell specifically for obtaining your Level 2 Certification. Go read the description about all the design features and why they help you achieve your goal. The small amount of sanding is a small fraction of your lifespan. Many people sand fiberglass for years using mask and eye protection, you will be spending maybe 20 minutes total sanding, so there's nothing to be alarmed about. The greatest part of the kit is the assembly video that shows every single step of the build process so you are guaranteed success.

mtnmanak said everything you need to know and has a nice build thread on it. I am building mine now.
 

OverTheTop

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Fiberglass is safe to work with using some precautions and correct PPE. Don't let some warnings put you off too much.

There is a thread here with very good advice on bonding composites:

Fiberglass is not that much harder to work with than the cardboard airframes and gives you a more robust rocket. I have only done fiberglass airframes after I got my L2. YMMV.
 

g.pitts

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Fiberglass is safe to work with using some precautions and correct PPE. Don't let some warnings put you off too much.

There is a thread here with very good advice on bonding composites:

Fiberglass is not that much harder to work with than the cardboard airframes and gives you a more robust rocket. I have only done fiberglass airframes after I got my L2. YMMV.
OTT I very much agree with you. I personally like the robustness of a fiberglass kit... hard landings are less of a concern. Of course the weight of fiberglass is another matter.
 

MetricRocketeer

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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
 

MetricRocketeer

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Hi crossfire,

I obtained my L1 certification on a LOC Minie-Magg. I wanted to use the very same rocket for my L2 attempt. However, I was advised that it would fly way too high on even a J-impulsed motor, and that therefore I should build a bigger and heavier rocket for the L2 flight.

Stanley
 
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