My level 2 cert

Hey everyone,

I would like your input on my level 2 cert design. Here is the ORK File. (https://www.dropbox.com/s/9vsdi414vwggs1u/Level2CertIdea.ork?dl=0)

a couple of things,
1. it is set up for dual deploy, currently I have the main in the upper section and the drogue above the motor
2. the Body Tube is PML Quantum Tubing, my school's rocketry club has some extra Callisto tubes that they want to get rid of
3. Right now, i think i will be using a StratoLogger as my Altimeter (any advice on it or a cheaper alternative is appreciated)

any other questions are appreciated and will be answered to the best of my ability (or more likely how far i have thought the rocket out...)

Hi, Your upper section is way too small to contain the main chute, the Nomex protector and the shock cord. Also your upper launch lug, is way way to high, for a Lev 2 I will seriously considerate rail buttons instead.

Area66 said:

Hi, Your upper section is way too small to contain the main chute, the Nomex protector and the shock cord. Also your upper launch lug, is way way to high, for a Lev 2 I will seriously considerate rail buttons instead.

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He is deploying the drogue from the upper (smaller) section, and the main from the larger section. (in the ork file) - which is the opposite of the info in the original post.

The choice of launch lugs or buttons should depend on the available launch equipment. At most launches I attend, rails are available, but I don't believe I have ever seen anything larger than a 1/4" rod.

The Stratologger and the Missileworks RRC3 are fine altimeters. Both are easy to use, and easy on the wallet

What about tracking? Have you ever flown this high? Dual deploy helps, but does not guarantee the rocket will land within visual range.

scsager said:

He is deploying the drogue from the upper (smaller) section, and the main from the larger section.

The choice of launch lugs or buttons should depend on the available launch equipment. At most launches I attend, rails are available, but I don't believe I have ever seen anything larger than a 1/4" rod.

Click to expand...

The launch I attend has both rails and rods, and the other person was right... I WAS putting my main above the ebay and drogue above the motor...

There are several reasons you shouldn't build this rocket.

The first and foremost reason for not building this is that you are using Quantum tubing. PML states right on it's website that you shouldn't use Quantum tubing for any rocket going over 80% of Mach. That is about 900 ft/s. Two of the three J motors in your simulations have velocities over 1100 ft/s

Another reason is more my personal thought, but with a 38mm MMT, the best you can do is a Pro38 6GXL 1115J530 motor that is only 10% of the thrust levels available in the L2 range. My opinion is if you are going to build a rocket to fly L2 motors, I would recommend at least a 54mm MMT so you can at least fly any size K motor and even some Pro54 or AMW 54mm L motors if you make the MMT long enough.

handeman, while i understand your sentiment, i would like to do this on a very inexpensive budget. and as it stands i will only be paying ~$150 for this entire rocket (80 for a StrattoLogger, $55ish for the motor, ~15 for other supplies/ shipping charges)

I am a college student and as such i do not have a ton of money laying around right now

I can certainly understand that. All I'm saying is, based on what PML states about Quantum tubing, I'm not sure it will hold up to an L2 cert flight. The speed will probably cause it to disintegrate.

i agree that is what they say on the website, but i expect my rocket to be both heavier and not as ideal as OR predicts... plus a friend is launching a Callisto with a Mach Breaking motor soon (TM) and so i will use his rocket to figure out if i need to glass my rocket

No I with you on the biggest bang for your buck . But if a vendor said don't go over this. Then you should spend the extra to glass it . It's cheaper to add 20-30 dollars to a project than lose everything and start all over . And would go 54mm and adapt down .

Chris like I said, i am really constraining my self to what the club has that they dont need, which is a bunch of 2.1 QT and a 54 cant fit into that... and i could glass it for free, i just have to deal with the beuracracy of my school to make sure that a LA can be in the lab with me... becasue after rolling 7 different CF tubes what can fit an N motor, i OBVIOUSLY dont know how to safely handle expoys and Fiberglass/CF

Hi B787 -

If you haven't already purchased the Stratologger, you might also want to consider the Eggtimer @ $40 or the RRC2+ @ $45.

I hear you on wanting to keep costs down. ChrisM and I both did very low cost L2 projects last year at Midwest power.

ChrisM went the "free" route using tubes obtained from rolls of carpeting, while I spent about $ 50 on a 4" nose cone and LOC tubing at Hobbylinc. I think we both got the cert special motor deal from Wildman.

I'm not sure what ChrisM spent in total, for me it was under $150. I flew single deploy with a 6-grain CTI J330. The 4" airframe, and draggy tube-fin design of my rocket kept it under Mach, and under 2800' altitude.

Handeman brought up the biggest concern - that Quantum tube and Mach speeds are not a good combination. Your Cert team or the RSO might not sign off on it.

I'm real interested to see what happens with your friends Mach Busting Callisto.

Cheers!

-Scott

Hey Scott, yes that was fun last year. Well my total cost for that build with out the motor ...... $60 an if some may have forgotten it was a 6.5 times upscale of the Estes hi flyer . Some said it would not fly right and crash . Well it never has done that straight up no spin . But wish the motor mount was bigger 54 or even 75mm . I am now building another one but with a 75mm so I can adapt down .

You can definitely use Quantum Tubing on an L2 Cert project - I did. As others have mentioned though, you have to be very careful about how hard you push the rocket. My project was a 4" diameter, 7ft tall rocket with a 54mm motor mount. Even still, the rocket can only fly J motors - a K of any size would destroy it (and even a full J pushes it right to the structural limit). You just have to ask yourself if you can live with that design knowing you can't really progress into serious L2 motors with it. That said, using only 2.1" QT with even a J350 or similar will likely exceed the limits of the QT. You're basically a step above minimum diameter with a 38mm motor mount, so I would have to think you'll need to at least glass the tube (if not use full composite) to ensure a safe flight. I like free stuff as much as the next guy and can definitely sympathize with wanting to do this on a budget, but some corners just shouldn't be cut and I have to think a load-bearing member such as your body tube is one of them.

Like others have suggested, see if you can buy down other parts of your project by using a cheaper altimeter and/or borrowing a parachute before risking the entire project by using an inadequate body tube, especially when the right one isn't all that expensive to begin with. If you do decide to buy a more substantial tube, I'd strongly suggest stepping up the diameter a bit to accommodate a 54mm motor mount. Hope this helps!

It is my opinion that glassing QT is a waste of time. Epoxy never bonded completely for me and any flexing of the airframe caused the glass to separate from the QT. I converted my L1 & 2 4" Endeavour to phenolic as quickly as I could.
If you can find some cardboard or phenolic tubes use them because epoxy will stick better.
However if your intention is to just get your L2 then build it strong and use the smallest J you can get. After you cert you will have a nice H & I motor flyer for small fields or just for fun.
Plus 1 on the suggestion of the RRC3 or RRC2+.

Sailorbill said:

It is my opinion that glassing QT is a waste of time. Epoxy never bonded completely for me and any flexing of the airframe caused the glass to separate from the QT. I converted my L1 & 2 4" Endeavour to phenolic as quickly as I could.
If you can find some cardboard or phenolic tubes use them because epoxy will stick better.
However if your intention is to just get your L2 then build it strong and use the smallest J you can get. After you cert you will have a nice H & I motor flyer for small fields or just for fun.
Plus 1 on the suggestion of the RRC3 or RRC2+.

Click to expand...

I agree here. If you're looking at just getting your L2 and keeping it cheap, then you can always fly it on H & I motors afterwards. I also agree with everyone else in saying that PML says DO NOT use QT to go over .85 mach, so I wouldn't recommend it. PML also says that QT is not intended to be used for fiberglassing or kevlar.

Good luck on your project.

A couple thoughts come to mind on the issue of speed. The first being that you could add considerable drag to the rocket. The downside is that getting a good aim for deployment timing would be harder. This might be something you can remove later.

Also, have you checked multiple motors to see if it might help? I realize that going cheap can limit the options.


Kirk

For your altimeter, you could get an Adept22 and a DDC22 for redundancy for a combined total of $80. Just a thought.

I don't think I would have space for redundant altimeters