LOC/Precision Force Ten L3 kit

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ECayemberg

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It's been a while since I posted a build thread, so let's roll with a new offering coming out of the LOC/PML shop in the near future!

Overview
The largest LOC/Precision production offering from Loc/Precision EVER! This monster towers over 10' in length, 7.67" in diameter, and is designed to handle full M's (perhaps into the N range) for L3 shots, without the need for composite reinforcements. To a degree, what's old is new again! Rewind 20+ years and the majority of L3 shots were huge paper and plywood rockets that majestically rose skyward on the likes of M1419's or M1939's. In the early 2000's, 2010's (is that a thing?), and through today, the migration towards relatively smaller, more dense glass birds has been the trend. I'll admit that my L3 was a 4" airframe, 3" hole convolute glass bird from the early Curtis Turner/Rocketry Online days! I love a variety...I like smaller glass birds, carbon fiber when appropriate, big Cardboard any day of the week, and perhaps my favorite: strategically reinforced cardboard or phenolic for true composite structure builds. This build is all about an "easy" L3 airframe that is affordable, can be constructed without any exotic materials, may be broken down into smaller ~30" sections for easy transport, and can handle full M's and beyond without modification. The best perk for me is that this monster bird is light enough to throw over the shoulder and carry to the pad without an army of support crew members!

Rules for the Build
Rules are self-imposed. Many of you know I like a challenge; and perhaps I like to challenge the status quo at times. These are not your rules, but they may be useful in assembling similar rockets.
1. No glass reinforcements allowed. Not even milled glass.
2. All joints between airframe sections shall be double walled (reinforced with a stiffy).
3. All ends of the tubes shall be sealed with thin CA. My veteran Loc Magnum has floated in Bong ponds twice and Ash Grove flooded field once; still flies great today. Yes it's cardboard, and yes sealing the ends of the tubes is beneficial.
4. Glassine shall be peeled from any external tube service being bonded to. Simple, easy, effective. Epoxy soaks into the virgin paper like a sponge, I like that, I'm not looking for an argument here. :)
5. Use common materials...ie: nothing I can't purchase within a 30-mile radius or local vendors. I'll save "fancy" for elsewhere.
6. Any other rules I've forgotten will be covered later. Who needs rules anyway; this is a hobby!

Why?
There's always a "Why" for my build threads. The common theme is that rocketry is fun and I'm a confirmed rocket addict. I have too many rockets, not enough space, don't really need additional rockets, but darnit I *need* to feed the habit. Other Why's are threefold:

1. I won this rocket at LDRS41 this past summer by flying the lowest Goblin (123' with dual deploy!) Thanks Loc/Precision; and Dennis for running events!
2. James Russell and I were talking about developing an example of Tripoli L3 bare minimum paperwork. I'll be posting on that later in this thread. Note, I'm one TAP, we're all a little different (most rocketry people are); the intent here is create a guide that exemplifies the bare minimum documentation for an L3 Project. One can, and is encouraged to do more, but it serves as a baseline for the administrative side of the L3 project.
3. The Loc boys are great friends. Occasionally I have the opportunity to play with "stuff". This project is a step in the product development of this sweet new offering coming down the pipeline. Bravo to the Rush fans...err Loc boys for tweaking the offering prior to full-on production!

Sneak Peak:
Without further ado, here's a dry fit early in the process!

Hey @troj
 

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I like this.

I'll be honest, my approach would be a little different, but that's what makes this fun and interesting!

Looking forward to seeing how you do this.

-Kevin
 
If you're planning to do an L3 attempt, the first step is to do a bit of research and reach out to appropriate parties BEFORE you start your build.

For Tripoli, visit the Level 3 Certification page on the Tripoli website: Tripoli L3
For NAR, visit the Level 3 Certification page on the NAR website: NAR L3 Site
For examples of others' L3 Project documentation, check out the TRF thread: TRF Sticky L3

Once you've filled your brain with ideas, devise a plan to pursue your Level 3 Certification. Remember... certification attempts are not the flights to reinvent the wheel. In other words, utilize your experience to increase odds of success.

Contact your TAPs or L3CC to approve your project prior to beginning construction.

You will need to present design details to your TAP members and obtain their signatures on the certification form before starting construction. You must provide sufficient information about yourself and your project for your TAP or L3CC to make an informed decision on whether or not you are ready to proceed. If you fly with your TAP's or L3CC's on a regular basis, a verbal conversation may suffice. If your TAPs or L3CCs do not know you, your history, and your intended project well, you will have to further educate them. Many ways to communicate your plan, but the onus is on you to communicate your plan, solicit feedback, and ultimately get the "Go" from TAPs or L3CCs. Understanding that the details will be filled in later, you and your TAPs or L3CCs are agreeing on your plan before you begin construction.

An example of basic info designed to "sell" your project to your team of TAPs or L3CCs is below in blue:

Introduction

Hi, my name is James E. Rocketflyerdude, Tripoli number 50555, Level 2 Certified, currently residing in Trego Hot Springs, NV. Like many other adult rocketeers, I rediscovered rocketry several years ago when a friend of mine invited me to a high-power launch. Following the launch, I joined Tripoli, built a rocket and certified Level 1 two months later. The following year, I achieved my Level 2 certification at LDRS. I have flown twelve Level 2 flights successfully with altimeter-controlled dual deployment and have decided it is time to make an attempt at Level 3!

Rocket Selection

I have chosen to begin with a Loc/Precision Force Ten, a 7.67” diameter by 11’ tall cardboard airframe, wood fin rocket, designed for the Level 3 process. The rocket is comprised of three sections of 30” airframe, topped with a 15” section of airframe and a 4:1 ogive nosecone. The rocket will be assembled with West System 105/205 epoxy thickened with 406 silica filler where necessary, and West System G5 epoxy where a fast cure is preferred. All joints between airframes will utilize a double coupler (Loc “Stiffy” epoxied inside standard coupler). All bonded joints to airframe will have the glassine paper layer removed for better epoxy adhesion. Please see the attached preliminary Rocksim of the Force Ten.

Electronics & Ejection Charges

I have gained experience and trust in Missileworks RRC2+ altimeters. Appreciating their reliability and simplicity, the rocket will employ dual RRC2+ altimeters, each wired completely independently. Altimeters will be armed using screw switches; for true redundancy, the first RRC2+ will be set for High tone, Apogee +0 seconds, 1000’ main event; while the second RRC2+ will be set for Low tone, Apogee +1 seconds, 800’ main event. A total of four Wildman ejection “lighters” will be used; the stock tubes hold up to 6 grams of black powder each. Planned charges will initially be set at: Apogee: 4.5 grams, Apogee +1s: 5.5 grams, 1000’ Main: 4.5 grams, 800’ Main: 5.7 grams. Ground testing will be performed to confirm charge sizing.

Motor Selection & Retention

Tentative motor selection will be an Aerotech M1939W in 98/10240 hardware. The motor will be retained with four sets of steel Z-clips and #10-24 bolts; old school style!

Recovery System


1” tubular nylon will be used throughout for both drogue and main recovery systems; both 35’ in length. Nomex chute and cord protectors will be used to prevent hot gasses from affecting the nylon recovery gear. 5/16” U-bolts, eyebolts, and Quick Links will be used throughout. #4-40 nylon shear pins will be used between the booster and payload to prevent drag separation and from the nosecone to payload joint to prevent premature deployment of the main chute. Parachutes will be Top Flight Crossfire for both drogue and main; final sizing to be determined based upon final mass of constructed rocket.

Launcher Requirements

The rocket will be built with 1515 rail buttons installed with #10-24 hardware, backed with T-nuts embedded in plywood backers shaped to conform to the inside diameter of the airframe. Rocket stability will be verified with an 8’ 1515 rail per the Pre-Flight Data Capture form.


Once you've obtained the signatures of your TAPs or L3CCs on the certification form, please proceed with your L3 Project!
 
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Love it! Can't wait to see this come together. One of my TAPs was talking about this rocket with another friend of mine, and that friend is now eagerly awaiting this kit to be released so he can build it for his L3.
Yes. Yes, he is.
 
Subscribed and following with great interest - it's a truly impressive looking beast, and I like the sleek fin profile! The NC in the pic in post #1 looks longer than the one supplied for, say, the Loc Bruiser or the 7.67" Patriot. Am I right or is it an optical illusion..?
 
My L3 was on a Loc Bruiser EXP 4" motor mount model with a 4" M. But we saw how the N motor worked out in Texas , Problem was the motor file for the sim did not come from CTI, but was the stock Sim file.

After the issue in Texas on the N motor, and I got the real file from Mike at CTI, I was like WOW that is why, HUGE SPIKE on Liftoff was missing on the sim motor file.

@troj was at my Hotel Room party when I was editing that N video and some other antics with some Hybrid motors were going on by others 😂

 
There was some science done on this on this Forum before the crash. I gave the video and the Altimeter data to two scientists here that did CFD data and determined the flat fins were the issue. If they can been tapered , they would not have "flapped" like the flat plate fins did.

They posted CFD animated pics of what happened to the fins in flight based on the video and data.
 
Parachutes will be Top Flight Crossfire for both drogue and main; final sizing to be determined based upon final mass of constructed rocket.
This whole write up is excellent and could (should) be easily posted up top as a sticky template for just about any req for a cert flight!

The only thing I would maybe add is modifying the sentence above slightly to read something like:

Parachutes will be Top Flight Crossfire for both drogue and main; final sizing to be determined based upon final mass of constructed rocket, which, from my simulations, I estimate to be NNg (NN lbs) on the pad and NNg (NN lbs) during recovery.

I think it is good for the TAP to know up front if they are dealing with a 40 pound rocket versus a 100 lbs rocket, for example. That weight guides a significant portion of the mentoring.

Thanks for taking the time to put this together!
 
Subscribed and following with great interest - it's a truly impressive looking beast, and I like the sleek fin profile! The NC in the pic in post #1 looks longer than the one supplied for, say, the Loc Bruiser or the 7.67" Patriot. Am I right or is it an optical illusion..?

Indeed! I used a PML 4:1 cone in place of the Loc plastic cone. I believe this will be an option in the future.
 
...and we're back! Let's build a rocket.

Fins

A few comments on the fins already. They are a sweet shape indeed; a long root chord with steep leading-edge sweep, and a dual taper back to rear of the rocket. Similar to the smaller HyperLOC line or the Air-X line, yet unique enough to make them different. 3/8" thick plywood...I like it!

The first four sets of Force Ten fins receive 15 degree bevels on all exposed edges:

20230716_193852.jpg

20230716_193913.jpg


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Following beveling, the high points get knocked down with a few quick passes of a sanding block equipped with some 60 grit, then ready for assembly!
 
Cone(s)

@Tim51 called me out on it. There is one fiberglass component on this particular build and it is the hand-laid PML 4:1 nosecone. While I enjoy the shorter 3:1 plastic cone on designs such as the Bruiser, V2, Warlok, or the Patriot, the longer length of the Force Ten plus the deeply swept leading edge fin angle screamed at me that a longer cone would be preferable. Good news and bad news there.

Bad news: they are not currently available from PML. Doubly bad news: the supply chain has been exhausted of existing stock. Triply bad news: 7.67" is a standard size for Loc/PML, but non-standard for the glass crowd, so hopes of finding a longer cone from CW, CT, MC, WM, CS, PH, or any other 2 letter acronym are pretty low at this point.

However...

Good news: there are efforts happening right now to bring back the line of PML hand laid cones back to market. Not yet, but SOON. More to come on this in a bit, but don't pester the LOC/PML dudes just yet.

In the meantime, the cone has been selected and test fit on the airframe! ;)

20230929_095216.jpg
 
Upper Payload Section Assembly

The Force Ten's airframe is comprised of three sections of 30" and one 15" section of LOC 7.67" airframe. As mentioned in the opening post, all sections shall be double-couplered... that is one coupler on the outside reinforced with a Stiffy Coupler on the inside. I used West Systems 105/205, filled with 406 Colloidal Silica for thickening to desired consistency for mating the couplers with their respective stiffies. I like to fully coat the ID of the coupler with epoxy AND fill the spirals on the OD of the Stiffy. Necessary... probably not, but it makes me feel better and that's what matters! ;)

Photo: not fully wet out yet, but getting there:
20230930_091748.jpg

In the meantime, a coupler bulkplate is assembled with an eyebolt. I prefer and use forged eyebolts, though the kits are generally supplied with bent eyebolts. Yes I've seen them "open up", as recently as this past weekend at NSL! Some thread locker and 5 minute epoxy are thrown on there, primarily to reduce anxiety.

20230930_110614.jpg

The Stiffy is inserted into the coupler, excess epoxy is pushed towards one end of the coupler. That epoxy is used to secure the bulkplate in place.

20230930_111013.jpg

20230930_112436.jpg

A fillet is added to the forward and aft ends of the bulkplate to lock it into place.
20230930_113247.jpg

Not my prettiest fillets ever, but they're functional!

Side note if you're still reading: This was a garage build. My garage workbench is more of a catch-all for working on chainsaws, mixing propellant, and whatever the wife and kids throw on there. Please excuse the less-than-glamorous ambiance of the build.
 
...and we're back! Let's build a rocket.

Fins

A few comments on the fins already. They are a sweet shape indeed; a long root chord with steep leading-edge sweep, and a dual taper back to rear of the rocket. Similar to the smaller HyperLOC line or the Air-X line, yet unique enough to make them different. 3/8" thick plywood...I like it!

The first four sets of Force Ten fins receive 15 degree bevels on all exposed edges:

View attachment 615316

View attachment 615317


View attachment 615318

View attachment 615319

Following beveling, the high points get knocked down with a few quick passes of a sanding block equipped with some 60 grit, then ready for assembly!

Those fins would look better with a fancy root extension. 😇

A question, will this have the LOC modular motor mount system?
 
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Upper Payload Section Assembly

The Force Ten's airframe is comprised of three sections of 30" and one 15" section of LOC 7.67" airframe. As mentioned in the opening post, all sections shall be double-couplered... that is one coupler on the outside reinforced with a Stiffy Coupler on the inside. I used West Systems 105/205, filled with 406 Colloidal Silica for thickening to desired consistency for mating the couplers with their respective stiffies. I like to fully coat the ID of the coupler with epoxy AND fill the spirals on the OD of the Stiffy. Necessary... probably not, but it makes me feel better and that's what matters! ;)
Interesting choice to reinforce with stiffies. As a reference, I used only the airframe stock for my Magnum on a full M. That being said the 7.67" tubing is flimsier than the 5.5" so this reinforcement is a good idea, especially if you want to fly higher thrust motors.
 
I like to fully coat the ID of the coupler with epoxy AND fill the spirals on the OD of the Stiffy. Necessary... probably not, but it makes me feel better and that's what matters! ;)

I 100% agree with fully coating the bonding surface - I learned this in a Lusty rebuild (remember that cursed rocket?).

I had to replace an upper tube, which meant peeling it off of the coupler. I was amazed at just how little epoxy was actually bonding the coupler to the airframe - I had use the standard "put a solid bead around the inside of the airframe and shove the coupler in" approach. The epoxy squeezes out.

Now, I take the time to use a tongue depressor to put a thin film of epoxy on both the coupler and the airframe. The bond is much better.

-Kevin
 
Interesting choice to reinforce with stiffies. As a reference, I used only the airframe stock for my Magnum on a full M. That being said the 7.67" tubing is flimsier than the 5.5" so this reinforcement is a good idea, especially if you want to fly higher thrust motors.
Clarification...the entire rocket is not double walled. It is only the couplers at the airframe joints that are reinforced with stiffies.
 
The Stiffy is inserted into the coupler, excess epoxy is pushed towards one end of the coupler. That epoxy is used to secure the bulkplate in place.

Which reminds me of the time I foolishly tried doing this with carpenter's yellow glue (Gorilla aliphatic resin) instead of epoxy - only to realise the glue was drying too fast, the tube fibres were swelling and the stiffener - in this case a 5.5" postal tube - had got completely stuck half way. Only solution was to saw off the protruding half, slather the end with glue and push it in from the other side. The two halves butted together in the middle and set hard in no time. It's still flying.
Anyway, apologies, sir, I digress. On with your excellent build.
 
...and we're back! Let's build a rocket.

Fins

A few comments on the fins already. They are a sweet shape indeed; a long root chord with steep leading-edge sweep, and a dual taper back to rear of the rocket. Similar to the smaller HyperLOC line or the Air-X line, yet unique enough to make them different. 3/8" thick plywood...I like it!

The first four sets of Force Ten fins receive 15 degree bevels on all exposed edges:

View attachment 615316

View attachment 615317


View attachment 615318

View attachment 615319

Following beveling, the high points get knocked down with a few quick passes of a sanding block equipped with some 60 grit, then ready for assembly!
What router bit are you using ?
 
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