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L3 Certification Build: 8" Upscale Frenzy

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Nathan

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I'm about to start building my level 3 certification rocket. This will be a scratch built 2X upscale of a Madcow Frenzy XL. It will be 8" diameter and 13'6" long. Weight on the pad should be about 71 lb.

Right now I have all the components execpt the av-bay coupler tube, which I expect to get in a few weeks. All the fiberglass except the fins was purchased from Ken Allen at Performance Hobbies. The fins were custom cut by Nat Kinsey at UpscaleCNC. Nat also made the plywood forward centering ring. The forward CR will be 1" plywood because my L3 advisor recommended that the forward CR be screwed to the airframe, which is a lot easier to do with plywood than G10 fiberglass.

The rocket will have a 75mm motor mount. I went with 75mm instead of 98mm because for the size motors that I will be using for this rocket (6000 Ns to 8000 Ns) there is a much better selection in 75mm than 98mm. Yeah I could adapt down to 75mm but I don't foresee ever buying 98mm motor hardware. At least not for this rocket. For my cert flight I plan to fly it on a CTI 5 grain 75mm M1670 Blue Streak, which sims at 4038 ft. With the most powerful 75mm CTI motor (6XL M2245 Imax) it sims at 7644 ft.

I expect to build this through the spring and paint it this summer. I'm already working on a paint design and yes this big rocket will be getting the full high polished paint job treatment, probably in four colors. If all goes as planned I will be doing my L3 cert flight when MDRA moves back to Higgs farm in the fall of 2017.



 

BDB

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Looks intriguing. I'm watching, if for no other reason but to see how you paint and polish something of that size!
 

mpitfield

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I cannot wait to see what you do with the paint job!

I have an 8" "Jumbo Darkstar" that I am slowly putting together, not for my L3 but I am building it along side my L3. I went with a 160mm MMT and had SCP CNC a custom thrust plate to adapt down to 98mm. I have a very cool paint job in mind but the thought of it intimidates me as it would really be stretching my current abilities. To give you a hint the rocket's name is "O" Canada. It is likely a 2019 or 2020 flight as I am hoping to do my L3 in 2018 but more likely 2019, we will see.

Looking forward to see your progress and good luck on the L3 attempt.
 

Handeman

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Hey Nat,

Not exactly how I would do it, but that's what's so great about this hobby. We each can do it the way we want.

One of the suggestions I have, go with the 98mm MMT, even if you never expect to need it, you never know. The other suggestion, do the cert flight at BattlePark! I want to see it!
 

Nathan

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75mm is enough motor for me. About $400 is the upper limit on what I'm willing to spend on a reload and that eliminates just about anything 98mm. At some point you have to say enough is enough.

But I'll definitely be flying it at BattlePark next season.
 

patelldp

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75mm is enough motor for me. About $400 is the upper limit on what I'm willing to spend on a reload and that eliminates just about anything 98mm. At some point you have to say enough is enough.

But I'll definitely be flying it at BattlePark next season.
I completely hear you, but one of my bigger rocketry regrets surrounds this very topic. I was offered a motor by Scott Raumberger back at the first LDRS held in Potter, specifically one of his really awesome sparky motors. The motor was a 98-3G and my 6" rocket only had a 3" MMT. I had to suck it up and fly it on my 76-3500 that I had made instead...
 

jd2cylman

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You can always adapt down. Not so much the other way... But I do hear you on the price of reloads in larger sizes.
I never planned on using a M1939, but when I purchased a 98/10240 case off of ebay (never intending to use it, at least in the near future), I got an email from the case seller wanting to know if I'd like to buy his TWO M1939 reloads. :y: I replied, "well I was just buying the case as a someday sort a thing, and I'm only (at the time) L2, and $1100.00 is a LOT of money...." His reply was "well, how about $600.00 for the pair" :shock: So, I called my buddy Griffin and asked his opinion. He told me in no uncertain terms to get a hold of that dude and make the deal, he'd take one of the reloads. And that is how my L3 (unbuilt rocket at the time) flew on a M1939 for my L3 at 270.00 UNDER list price. Worth every penny. But, I also see your point, and there are a lot of big 75mm motor choices and more if CTI gets back to full production. And the Loki 75mm N might be a choice.
 

Nick@JET

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You can always adapt down. Not so much the other way... But I do hear you on the price of reloads in larger sizes.
I never planned on using a M1939, but when I purchased a 98/10240 case off of ebay (never intending to use it, at least in the near future), I got an email from the case seller wanting to know if I'd like to buy his TWO M1939 reloads. :y: I replied, "well I was just buying the case as a someday sort a thing, and I'm only (at the time) L2, and $1100.00 is a LOT of money...." His reply was "well, how about $600.00 for the pair" :shock: So, I called my buddy Griffin and asked his opinion. He told me in no uncertain terms to get a hold of that dude and make the deal, he'd take one of the reloads. And that is how my L3 (unbuilt rocket at the time) flew on a M1939 for my L3 at 270.00 UNDER list price. Worth every penny. But, I also see your point, and there are a lot of big 75mm motor choices and more if CTI gets back to full production. And the Loki 75mm N might be a choice.
I thought the same thing, I'll never fly a 98, but sure glad I went 98 - since I grossly underestimated my final weight. 72lb 6" even with a M1939 gotta watch the initial thrust. Oh I'll only fly once every couple years...but I've already purchased another M1939 and have a line on an O3400.

But your a smart guy and a great rocket builder. Just give yourself options when building something that big, you may make a trip to Argonia or MWP some day.. hint. Looking forward to following your build.
 

pondman

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Your project is impressive! I cannot say enough about up-sizing the MMT to 98mm even if you think you will never fly anything that big. You may have the opportunity to fly a 98mm Research motor from one of the great motor makers on the east coast. Stranger thing have happened....
 

Nathan

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I already have all the parts for the 75mm MMT, including the Aeropack retainer, so that is a done decision.

And now on with the build . . .
 

fyrfytr310

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I'm in. Even though it is just a 75mm :roll::roll::roll: I kid, I kid.

Have fun with the build! You are wise to take your time.
 

Nathan

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The forward CR is 1" birch plywood, made from two 1/2" plywood CRs glued together with Tite Bond wood glue. I rubbed them together for a minute until glue was coming out all edges, then clamped them and wiped off excess glue.

 

Nathan

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The motor mount will be reinforced with three 1/4" stainless steel allthread rods. Welded eye nuts on the forward ends of the rods will be used as attachment points for the recovery harness (using a really cool 3-point Y harness that Ted Chernok from OneBadHawk made for me). I drilled 9/32" holes through all four centering rings for the rods (one plywood, three G10).

 
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Nathan

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I'm getting ready to start cutting fin slots. Normally I use my little Dremel rotary tool for cutting fin slots but it really bogs down when cutting through fiberglass. I've got a lot of cutting to do here with six big fins and wondering if there is a better tool for the job.

Has anyone ever tried using a Dremel Saw Max for cutting fiberglass fin slots? I'm thinking about getting one. $75 at Amazon, not too bad if it does a good job.

 

AeroAggie

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I'm getting ready to start cutting fin slots. Normally I use my little Dremel rotary tool for cutting fin slots but it really bogs down when cutting through fiberglass. I've got a lot of cutting to do here with six big fins and wondering if there is a better tool for the job.

Has anyone ever tried using a Dremel Ultra Saw for cutting fiberglass fin slots? I'm thinking about getting one. $129 at Amazon, not too bad if it does a good job.
What cutter are you using on your rotary? I've found that this guy cuts through fiberglass like butter.



But if you have a way to keep the ultra saw straight, I bet it'll do a great job.
 

Nathan

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Thanks, I'll try that. I've just been using the standard solid black cutting disks with my Dremel rotary.
 

Nathan

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I bought the cutter for my Dremel rotary tool recommended by AeroAggie and terryg, which is a EZ544 1-1/2" Carbide Cutting Wheel. Wow that made a big difference. Much easier than cutting with a standard cutting disk. This evening I cut all the fin slots. Took me about 30 minutes. Very loud. Yes I wore a dust mask, ear protectors, and safety glasses.

Then I spent another 30 minutes cleaning up the fiberglass dust that was all over my shop. This is the room over my garage. Some day I'm going to remove the carpeting in this room and put in hardwood floor. Easier cleanup.

 

AeroAggie

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Oh yeah, forgot to mention DUST FROM HELL. Glad it worked out for you! :cheers:
 

NateLowrie

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Slots look very nice. Keep up the good work. Did you do your initial documentation packet yet?
 

mccordmw

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Looking great! I look forward to learning from your build as I slowly progress on mine.

+1 On the diamond cutting wheel. It makes amazing work of fiberglass tubes, and the wheel likes to keep going in a straight line, so perfectly aligned slots seem to come out automatically. It also does wonders on 1/8" plywood.
 

kcobbva

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Wow Nathan! This is going to be Awesome! Gotta agree with both of Jeff's points! 98mm and more importantly, launch at Battlepark so we can all watch and cheer!!!!!!!! As someone else said already, I can't wait to see the paint job. As your L3 I bet this thing will be the best you've done yet! Look forward to following your build!
 

Nathan

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Slots look very nice. Keep up the good work. Did you do your initial documentation packet yet?
Yes I did. My NAR L3 advisor is Dave Weber. He gave me some good suggestions for improvements on my initial design.

Looking great! I look forward to learning from your build as I slowly progress on mine.
+1 On the diamond cutting wheel. It makes amazing work of fiberglass tubes, and the wheel likes to keep going in a straight line, so perfectly aligned slots seem to come out automatically. It also does wonders on 1/8" plywood.
Another nice thing about this cutter wheel is that unlike the standard cutter, with this one you can also shape using the side of the wheel. That comes in handy in areas where the slot is not quite wide enough.

Wow Nathan! This is going to be Awesome! Gotta agree with both of Jeff's points! 98mm and more importantly, launch at Battlepark so we can all watch and cheer!!!!!!!! As someone else said already, I can't wait to see the paint job. As your L3 I bet this thing will be the best you've done yet! Look forward to following your build!
Yeah the paint design for this needs to be something special. Still working on it. All I can say for sure so far is that it will be a four color paint job using Restoration Shop metallic lacquers, and lots of polished clearcoat.
 

kcobbva

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Yeah the paint design for this needs to be something special. Still working on it. All I can say for sure so far is that it will be a four color paint job using Restoration Shop metallic lacquers, and lots of polished clearcoat.
Knowing your work, this will probably be the longest part of your L3 build!! :)
 

NateLowrie

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Yes I did. My NAR L3 advisor is Dave Weber. He gave me some good suggestions for improvements on my initial design.
Can you share the packet? Always nice to see other's thought processes.
 

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