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A4 (V2) for my L3
#1
Well it appears that the wheels are really falling off over at TRF, so I'm transfering my L3 build thread here.  This will take a few days, so bear with me.  I will be copying in people's posts from there, so the conversation makes sense.

Dang shame, I use to really like it there, but as Bob observed...

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#2
Welcome to Rocketry center! Yeah things are not looking pretty for TRF, I've been putting a majority of my posts here instead of there. Well good luck with the build, looking forward to seeing PICTURES of it.

NAR# 98194
Level 1: CTI I-216, 3,043'
Level 2: CTI K-740, 5,999'

Personal altitude record: 12,400' CTI L395
2014 total impulse: 9,018.2 Ns (76% M)
2015 total impulse: 7,171.7 Ns (40% M)
2016 total impulse: 18,664.2 Ns (91% N)
2017 total impulse: 8,281.1 Ns (80% M)
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#3
Well the title pretty much says it. I did not start this project with designs on getting my L3. Instead it started with my desire to make a V2 with some presence, i.e. big. Well, the V2 is pretty stumpy, so to get one even close to the 6' range requires a 7.5" diameter, which requires some weight (15-20 lbs). Which is getting it into the ideal range of my "been drooling since I heard it existed motor, the M650W...10 seconds of White fire and smoke, yes please! So this project became an exercise in designing and building a V2 for that motor, and one that is light enough to also fly on full-J/baby-K range as well, because M motor flights will not be regular occurrences for me. Like I said, the central goal of this project isn't "get my L3" it is Build a V2 to fly the M650W in, the L3 is just a co-requisite.

I have recently gotten the go ahead to start building from my L3CC member, so I'm doing this thread as much to make sure I document the build properly as anything else. I'm going to be trying some new, to me anyway, techniques along the way; vacuum bagging, composite fins (plywood, end grain balsa, carbon fiber), adjustable nose weight, etc.

Anyhow, at the start of my build threads I also try to note a few things up front.

- Do NOT assume that I know what I'm doing. I.e., if you are new here, don't just think my way is THE way. There are many paths to rocketry Zen (I think I stole that from samb). Most of my build techniques I stole from qquake2k, sodmeister, legrandudu, dixonj93060, etc. anyway. In other words, this is all their fault!

- I suck at photography

- I can't spell, and I would have learned by now if it was going to happen.

- I build at a glacial pace, as such I am targeting July-Nov of next year for the flight.

- I know there are commercially available kits that fit the bill, but I like to scratch build.

- I am overly detailed in descriptions, I learned from threads like this, and I'm not charging.

- I am fundamentally opposed to the keeping it low, slow, and simple for a certification. If that is your deal, great, but low, slow and simple just isn't what I enjoy flying most of the time. Certify what you like to fly, if you fail, try again. As long as you do it safely, that is all that maters.
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#4
-everyone has their own build techniques, it's what makes each rocket unique.

-not everyone is good, that's why we leave it to the pros a lot.

-I know a few like that...

-take your time. It's an L3!

-scratch built FTW!!

-a good thing in my book

-low and slow for the lose

NAR# 98194
Level 1: CTI I-216, 3,043'
Level 2: CTI K-740, 5,999'

Personal altitude record: 12,400' CTI L395
2014 total impulse: 9,018.2 Ns (76% M)
2015 total impulse: 7,171.7 Ns (40% M)
2016 total impulse: 18,664.2 Ns (91% N)
2017 total impulse: 8,281.1 Ns (80% M)
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#5
Straight from my L3 submission:

This level 3 certification project consists of a scratch built sport scale V2. The airframe will be made of 7.5” phenol tubing wrapped with at least one layer of fiberglass. The electronics will be housed in an 8” long donut electronics bay with a 4.0” opening. The use of a donut electronics bay will allow for the use of 75 mm motors fitting cases up to the AT 75/6400. This configuration allows for separation at the airframe-tail cone joint at apogee (for drogue deployment) and separation of the nose cone for main deployment (at or around 900’). The nose cone will be a standard LOC 3:1 plastic nose cone with an internal 3.9” ID phenolic coupler to function as the main chute bay. The fore end of the tube will be topped by a ½” plywood ring with a 2.25” center hole to provide access to the fore end of the NC. A bulkplate will attach to this ring, and act as the shock cord attachment point and base of the adjustable nose weight. Lead weights will be cast that allow for up to 9 lbs of weight to be added to this space. Additionally, the space between the internal tube and the NC will be used as a tracker bay, and will be accessible through a 1.25” hole in the aft CR for the NC tube. The tail cone will be constructed from a 5:1 plastic nose cone. The motor mount will be 75 mm phenolic tubing and motor retention will be with an Aeropack flanged retainer. The fins will be constructed with weight savings and strength in mind, using 3/8” high quality plywood edges with end grain balsa center. These will be laminated with at least one layer of carbon fiber. The fins will have 12.5” fin tabs. The overall rocket length will be 64.1” with a dry weight (without electronics, recovery gear, or motor) that is estimated to be around 205 oz.

[Image: 22391080260_4f77423791.jpg]

Note: The fin tabs look wonky, but that is more an artifact of OR and my laziness. They will end at the CR that currently cuts into them.
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#6
"The Bob Stash"

The project began at "The Bob Stash".  This is a large collection of parts, kits, and rockets left to DARS by a deceased member, Bob.  The stash is a much beloved source of far below retail parts for a donation to the club.  Also, I think Jack wants his shed back, which probably helps with the deals.  Fortunately the stash yielded me my high dollar components, 7.5" phenolic tube, 75mm phenolic tube, a 3:1 NC and a 5:1 NC.  A 4:1 would have been more accurate for a V2 boat tail, but I can happily live with the discrepancy for the savings...sport scale, not scale.

[Image: 21957844283_ae6000c34e.jpg]

Interestingly, the 5:1 NC had a line marked around it, which I realized days later turned out to be exactly where the cut should be for the boat tail.  The short piece of 7.5" phenolic that I originally took in case I needed to make a coupler, turned out to be 17.75"...exactly what it should have been.  Apparently, I bought Bob's V2 project.  Our V2 will fly Bob!
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#7
What a stroke of luck having all those parts be exactly what you needed.

Ps. You don't need flikr to post photos here.

NAR# 98194
Level 1: CTI I-216, 3,043'
Level 2: CTI K-740, 5,999'

Personal altitude record: 12,400' CTI L395
2014 total impulse: 9,018.2 Ns (76% M)
2015 total impulse: 7,171.7 Ns (40% M)
2016 total impulse: 18,664.2 Ns (91% N)
2017 total impulse: 8,281.1 Ns (80% M)
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#8
I know I don't need Flikr, but doing it with imbedded Flikr links means I can write it on one forum and copy paste the entire thing from on forum to the other with no additional modification required. I'm not completely ready to pull the plug at TRF, but I'd like to contribute to the content here too in hopes this place can grow.
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#9
Ok. That makes sense. I just never like using a 3rd party service.

NAR# 98194
Level 1: CTI I-216, 3,043'
Level 2: CTI K-740, 5,999'

Personal altitude record: 12,400' CTI L395
2014 total impulse: 9,018.2 Ns (76% M)
2015 total impulse: 7,171.7 Ns (40% M)
2016 total impulse: 18,664.2 Ns (91% N)
2017 total impulse: 8,281.1 Ns (80% M)
Reply
#10
Glassing the bt

As I mentioned, Bob did me a solid and cut the tube for me, so no need to do that. I am going to glass the thing though. I'm not a glass everything guy normally, but this thing is going to be taking a good bit of force, so the additional weight is well worth it.

I used Soller Composites Fiberglass Sleeve, Soller Composites Heat shrink tubing, and US Composites 635 Laminating Resin and Medium Hardener. This sleeve is awesome stuff, any moron can fiberglass well with this stuff, which is why I use it. It is admittedly more pricy than cloth, but there is almost no learning curve.

Soller composites link: http://www.sollercomposites.com/comp...rbonfiberglass

I used a single layer of the 7" light, natural sleeve...this is roughly equivalent to 9.5 oz cloth.

To use the stuff you simply slide it over your tube, and secure it somehow (I like zipties around the pvc pipe I have everything on. There are 2 CRs recessed inside the tube about 4" from each side. Sleeve this size would probably not need secured like this, so all that excess could be avoided. I have used small diameters on 38 and 54 mm projects, and those are really helped by securing with zipties.

One note on fiber glassing if you haven't done much before. PREP EVERYTHING IN ADVANCE and lay out your work area neatly.

[Image: 22553273566_328eeae03e.jpg] [Image: 22392432829_870bba49d4.jpg] [Image: 21958059713_b3f4d7615e.jpg]

Saturate out the cloth, a small roller helped immensely for this part. This tube took a full double batch (8 pumps total). Slide the heat shrink over (cut extra, it shrinks longitudinally also), then work the tubing making sure not to hotspot the tubing it can melt/tear. the tubing will eventually pull down very smoothly, and working from the inside out will push most of the excess epoxy out the end. For something this size you may get a pool inside, you can prick it with a pin to drain the pool with little damage to the end product finish. If you do melt a hole you can just slide an extra piece of tubing over and shrink it as a patch.

[Image: 21956508644_ed0d8e3652.jpg] [Image: 22392429439_3bbda288fb.jpg] [Image: 22553266486_6cb83edf45.jpg]

Once the heat shrink is cutoff I came over the top with a light coat of epoxy and let that cure. This is just to fill any pinholes. After that had cured for two days it was sanding time...what doesn't involve sanding with these builds? In the end I have a strengthened tube, and bonus from the heat shrink the sleeve wraps over the face of the bt giving a smooth surface that should provide extra zipper resistance.

Rough sanded and ready for building, priming:

[Image: 22553265096_aef8364dd3.jpg]

Starting weight: 502 g
Ending weight: 767 g
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