L3 Cert Project - Experiencing a Significant Gravitas Shortfall (Formula 200)

Now I've completed the Level 2 cert, it's time to move on to my Level 3 cert. At the July launch I picked up a Formula 200 kit from the good folks at AMW. Gloria sealed the deal by throwing in an aeropack 98mm retainer for free. It will make a capable aireframe for the Level 3 attempt. Given the waivers at the Sod Farm and Higgs, I wanted to go with something that would be relatively heavy and big. The Forumla 200 will come in about 50-55 lbs unloaded wihich will allow it to handle a wide range of M and N motors and stay within the waiver.


In case I haven't stated it before, my big 3-5 year goal is send a 1kg payload to over 100,000 ft. and recover it. This project is the next step in that goal. The goals of this project and how they relate to my overall mission:

• First and foremost, obtain my L3 cert. The L3 is required for a flight that high and I can re-acquaint myself with this level of complexity.
• Create a robust airframe that can be used a test bed for the larger 75mm and 98mm experimental motors I will be developing. My plan for the 100,000 ft. flight calls for using experimental motors and this airframe will serve as an eventual flight test bed for the larger motors.
• Gain experience with the ARRD recovery configuration in a larger rocket where the recovery forces likely to be large. I have used the recovery setup on my Level 2 cert. It is the recovery method I would like to use on the sustain for the 100k.
• Machine a custom designed aluminum thrust ring for the rocket. I expect to be make some custom bulkheads for the 100k project and a thrust plate is a nice, easy start on gaining experience in doing that. This shouldn't be much different than the normal CNC work I do.
• Develop the tools, ground support, and processes necessary to support a large complex launch. Off the top of my head I would like to use this project to:
  • Develop a better transport rack setup
  • Develop better work cradles for holding the rocket during assembly and prep.
  • Build a proper case for the LCD recievers for the TRS altimeter.
  • Develop a better prep system in regards to a 2 person team. Need to develop a process of running through the checklist better with double confirmations.

Attached is the Rocksim file and the preliminary project report I sent to my TAPs for approval. If you review the documents, any suggestions, concerns or other feedback would be appreciated.


My goal is to have the project done and ready for launch by the end of October. I am not really doing anything I haven't done before so this shouldn't be a problem. If we have Red Glare in November I will launch then if ready, else it will have to be at LDRS in April unless there is another launch in November within 5 hours of central PA I don't know about.

View attachment Level 3 Certification Project - Experiencing A Significant Gravitas Shortfall.pdf

View attachment Experiencing A Significant Gravitas Shortfall.rkt

Looking good Nate.

I did a custom thrust plate for my L3 flight:


For fabrication details check out here: https://www.ausrocketry.com/forum/viewtopic.php?f=6&t=4612&hilit=nike+smoke&start=28

OverTheTop said:

Looking good Nate.

I did a custom thrust plate for my L3 flight:
View attachment 302490

For fabrication details check out here: https://www.ausrocketry.com/forum/viewtopic.php?f=6&t=4612&hilit=nike+smoke&start=28

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I am really glad you replied. I took a look at your thread and that plate is gorgeous, awesome, and very practical/lightweight. I have some ideas of yours I want to implement in future builds. The sleeve around the motor tube is really nice. You did a mighty fine job on everything.

The plate that I am doing is actually pretty simple in comparison. It's going to be very similar to the SC Precision thrust plates though I am planning to web out the back for some weight reduction. I already have a 98mm aeropack retainer so it just makes sense. On future builds though I am probably going to use a 2 piece plate with the top piece as motor retention and replicate your sleeve system.

Don Reago, who just got his L3 at MDRA with a Formula200 in April, also had an aluminum thrustplate made. His was made by SC Precision, I think.

Worked out the thrust plate. Here's the drawing. Should machine it up this week and get it anodized type II.

Note: I had a hard time finding the aeropack retainer bolt hole pattern. I finally measured it, but for those that are looking for it the screws are #8-32. There are 12 holes equidistance around a circle. The bolt circle is spaced 3/8" from the inner hole. You can see it clearly in the drawing.

View attachment Thrust Plate.PDF

This is why I'm going to win the drag race! The extra weight of your fancy thrust plate will tip the scales my way. BWAH HA HA HA HA HA HA! :dark:

Nice drawing, who is doing the machining? Are you doing it yourself? I never bother with a drawing that polished when I'm doing my own work. You should have seen my L3 wiring diagram... It was a rough hand sketch that got stuck in the binder with the rest of the paperwork. Anyway, looking forward to seeing how your thrust plate, as well as the rest of this project, turns out. Good luck!

Bat-mite said:

This is why I'm going to win the drag race! The extra weight of your fancy thrust plate will tip the scales my way. BWAH HA HA HA HA HA HA! :dark:

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We'll see...:wink: I recall that you're foaming your fin can? I would bet the foam will add more weight than the thrust plate. It's also not that heavy. The comparable 8in to 98mm SC Precision plate is a tad over 21oz and it doesn't have the pockets I put in for weight reduction. I expect mine to come in around 16oz.

This is going to be fun! :w: When am I going to see a build thread for yours?

AdAstraPerAspera said:

Nice drawing, who is doing the machining? Are you doing it yourself? I never bother with a drawing that polished when I'm doing my own work. You should have seen my L3 wiring diagram... It was a rough hand sketch that got stuck in the binder with the rest of the paperwork. Anyway, looking forward to seeing how your thrust plate, as well as the rest of this project, turns out. Good luck!

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I am doing the machining. Just have to fit it into the production schedule on the mill. One of the reasons for the drawing was documentation for others benefit in case they want to follow suite. The other is I am exploring the idea of a production line of various thrust plates. The drawing took literally 5 minutes via Solidworks so it wasn't too bad.

NateLowrie said:

This is going to be fun! :w: When am I going to see a build thread for yours?

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I, um, opted out. :grin: I barely have time to work on mine, and I really don't have time to take pictures and upload them, etc.

Right now, I have just about everything above the switch band done. Need to find time to start on the fin can, rail buttons, MMT, etc. I am really taking it slowly.

This is going to be a little more exhaustive of a build documentation to point out build techniques. I want to make sure it's thoroughly documented.

Put the Av-Bay coupler in the back end of the fin can and use the fin slots to mark 3 lines spaced equidistance around the coupler. These will be used for the drill positions for the button head cap screws holding the av-bay to the fincan and payload tube.


Use a piece of angle iron to extend the lines all the way to the other end of the coupler.


I slid the switch band on the coupler and used a ruler to mark the switch band with 3 lines for the vent holes.


Using a ruler, I put tick marks at 8in an 10in from the end to mark where the switch band goes.
I put the coupler in the fin can airframe and used the end of the tube to mark a perfect circle where the marks were.
Next, I needed to mark the center point in between the 2 lines so we can position the switch band vent hole in the middle. I do this by taking a piece of paper. I align the edge on one line and mark the paper where the second line is.
I then fold the end of the paper to the marked spot which results in a piece that is half size of the circumference part between the marked. I can then put it back on the tube and make a tick mark on the tub where the paper is folded up, resulting in a spot that is centered between the 2 lines.
The switch band is then aligned to that mark.

The following is my epoxy adhesion preparation procedure. I will only be detailing this once:

1. Glove up. You will not touch any parts with oily skin until the epoxy is set. If your gloves touch any skin you will stop and change out the gloves.
2. Use denatured alcohol with a lint free cloth to wipe any mold release oils and other dirt from the part. If you don't do this you will sand the mold release into the part with will result in a suboptimal bond.
3. Sand both parts to be joined. Use 200 grit paper which is an aerospace standard. Sand in all directions. Do not sand into the fiberglass fibers.
4. Wipe parts using denatured alcohol with a lint free cloth.
5. Test for water break. If no break, go back to step 3.
6. Mix epoxy by weight according to directions. ALWAYS mix by weight an never rely on pumps. Stir for at least 1 minute.
7. Mix any fillers or additives in. Stir for at least 1 minute.
8. Apply epoxy in an even layer to both parts if possible. If doing a tube to coupler or similar bond where only 1 surface can be applied that is ok.
9. Join parts. Clamp if possible.
10. Start timer for cure or wait overnight.

Sanded the inside of the switch band and the outside of the coupler where the band will go with 200 grit sandpaper.
Weighed the epoxy. This is the last pic of epoxy on the scale I will be showing...
Coupler is bonded in place waiting for full cure. Note for tubes we only apply epoxy to the inner coupler tube.

I haven't stopped working on this. Life got in the way. We had our 2nd son on 10/17 and my availability to work on rocket projects has been somewhat limited.

I managed to get the thrust plate done. It is anodized Type II hardcoat and fits the Formula 200 tube perfectly. The weight came in at 1.6lbs which is about where I expected it. That's still much lighter than if I would have foamed the fin can. It comes in lighter than the SC Precision plate which does not have the ribbing on the back. The Aeropack retainer fit perfectly.




The plate is designed to be bolted onto the back centering ring using 10-32 bolts. I printed the drawing of the mount holes and taped that to the centering ring. I then used the template as a drill guide. Once the holes were drilled I installed the PEM Nuts. To do this, I took some socket screws and used the screw to press the nut into the hole. Once the nuts were installed I did an epoxy fillet around them to ensure they stay put (for some reason I don't have a picture of this, but will make sure to snap one before I glue it in place).



I made a production run of 10 plates. If you would like one, they are $85 which includes shipping to the continental US, (4) 10/32 socket flat head screws, (4) 10-32 PEM nuts and a printed drill template for the nuts. PM me if interested.

Got to work on the internal mounts for the Mobius camera setup and I had a few questions I was hoping someone could answer:

• One of the mounts has the camera facing downward. The lens module will be held in the shroud while the rest of the camera is internal.
• I want the camera to capture the bottom portion of the rocket in no more than 1/3 of the screen.
• I realize camera position on the rocket matters but I don't know how much. I am planning on placing the camera either 8' or 3' from the bottom.
• I can experiment to find the best setup, but I was wondering if anyone has good numbers for tilt angle of the lens and how far it should stick into the shroud?
• Also, does anyone have a good starting point for shroud size?

The goal is to create some 3D printed mounts to mount the bulk of the mobius cameras internally. I realize I can mount them externally on a shroud but I would like to develop a minimal profile setup I can use on high altitude flights in the future.

Lots of work done, I just need to get the pictures and documentation up here. At this point, all I have left is finishing up the ebay, ground testing, and painting. We are on track for an LDRS launch(es). I'll try to get all of the completed work up in the next few days.



Marked between the fin slots a line for the 3 1515 rail buttons that are going on the rocket. In order to make the mark I took a piece of paper, put the end up to one fin slot, then marked it where it met the adjacent fin slot. Then, I folded the paper so the end of the paper met the mark. Now the crease is halfway in between. I laid it back down, marked 2 guide marks and finished the line using a clamped angle iron as a straight edge. Then I marked the locations for the 3 rail guides. Theyare spaced at 4in, 16in, and 26in from the end of the body tube.



I then drilled the hols for the 2 aft most holes. These need to be installed before we insert the motor mount because afterwards we can't get to it.

To back the rail buttons I am using a 10-32 PEM nut. The nut was installed using the screw from the rail button to press it into the hole. I applied some ultra thin CA to the nut/hole intersection to intersection of the nut and fiberglass to 1) stiffen it up the hole and 2) hold the nut in place on the bottom side. After the CA was cured, I prepped the nut and airframe for epoxy and epoxied around them to secure in place.

Here is a shot of both rail buttons and their relationship to the fin slots. As you can see, if I didn't do this now, access later would be difficult at best.
Finally, I drilled the holes for the epoxy injection. I used 4 holes equally spaced on each side of the fin slot. The holes were centered .25in from the edge.

Next up is the fin can.

First thing was installing the forward 2 centering rings. I used a clamped on collar to keep the centering rings straight while the epoxy dried. The middle centering ring has partial fillets on the inside to leave room for the fins.

I had a minor problem inserting the motor mount into the tube. From about 4 inches in front of the fin slots to the rear of the tube the tube was slightly out of round. My motor mount tube with the top 2 centering rings just dropped down into the top of the outer tube till about 4in from where it needed to be. Then I had to tap it down with a mallet to get it seated properly. Before I tapped it all the way down I spread epoxy on the tube above the middle ring and injected some in the the middle of the 2 rings through a drilled hole. I then tapped it the rest of the way and check fit of the motor tube to make sure it didn't displace the thrust plate. The last thing that I did was hand fit the back centering ring on the motor tube to keep it centered. The fitting of that ring forced the out of square tube square.



Next up was gluing the fins down by the root. I used the fin alignment jig I had made to get the fins centered. I used a bungie to apply downward pressure and a clamp to hold the fin to the jig. Each fin was glued and let to dry for 8 hours before moving on the the next fin. After the fins were done, I removed the back plate to inspect the work. Then, I put glued the back thrust ring into place with epoxy. I made sure to put enough on the MMT, inside of the outer airframe, and the back edge of the fins to get a good solid fillet on each when I pushed it flush.

I'm a long way from Level 3, so I have nothing useful to add other than "Nice Rocket!"

But I do really appreciate the name. I've been considering building a series of rockets using the same inspiration - my minimum diameter Mongoose is going to be "Transient Atmospheric Phenomenon", I'm designing a sci-fi looking "Liveware Problem", and at some point I'll get around to making a small rocket with a huge engine for the name "Mistake Not..."

(for those confused, these are all ship names from the Iain Banks "Culture" series of sci-fi novels)

Oberon said:

I'm a long way from Level 3, so I have nothing useful to add other than "Nice Rocket!"

But I do really appreciate the name. I've been considering building a series of rockets using the same inspiration - my minimum diameter Mongoose is going to be "Transient Atmospheric Phenomenon", I'm designing a sci-fi looking "Liveware Problem", and at some point I'll get around to making a small rocket with a huge engine for the name "Mistake Not..."

(for those confused, these are all ship names from the Iain Banks "Culture" series of sci-fi novels)

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Yes! You are definitely one of the few that got the references. Banks is relatively obscure but one of my favorite Sci-Fi writers. My level 2 was "Nervous Energy" and my level 1 was "Only Slightly Bent".

There are a lot of really good rocket names that could could from Culture ship names... My next projects are a 8in AGM-33 Pike that shall be named "What are the civilian applications?" and a huge 12in dia 20' rocket that I am considering calling "So Much For Subtlety", "Zero Credibility", "Poke It With A Stick", or "Big Sexy Beast". At some point I think you have to use "Ablation" for either a mach buster or something stupidly slow like a saucer. I compiled a list of names throughout all the books, if you want it I'll post it for reference.

Also, I am saving "Clear Air Trubulence" and "Bora Horza Gobuchul" for some special future builds.

Also a fan of "Death and Gravity", "Ultimate Ship the Second", "Frank Exchange of Views", "Lightly Seared on the Reality Grill", "Refreshingly Unconcerned With the Exigencies of Veracity", and "Just the Washing Instruction Chip in Life's Rich Tapestry".

NateLowrie said:

My next projects are a 8in AGM-33 Pike that shall be named "What are the civilian applications?"

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I've looked at the 8" Pike as possible L3 fodder, but I think they just raised the price by a couple hundred. These big rocket kits get expensive.

Nytrunner said:

I've looked at the 8" Pike as possible L3 fodder, but I think they just raised the price by a couple hundred. These big rocket kits get expensive.

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That's for darn sure! Wait for a sale. You might get 10 - 20% off.

Bat-mite said:

That's for darn sure! Wait for a sale. You might get 10 - 20% off.

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I just got an un-built kit from Kevin on the yard sale for $600.:wink: Too tempting to pass up.

Regarding the camera:

Brian (Ravenex) was kind enough to rush a custom request through of his knew through wall camera shrouds (see https://www.liquidfyre-rocketry.com/Cat-Mobius-ActionCam-Shrouds). He's going to provide a sled sized for a 8in airframe and a standard 4in shroud. I am going to cut the wings off the shroud and epoxy it into place. I may still run a fiberglass cloth over it, but 1/2in epoxy fillets should be enough.

I got 2 ActionCams from Amazon. One will be downward facing using the shroud. The shroud will be mounted on the fincan, since I am not using the top part of the can for recovery. The other will face outward and be situated in the nosecone.

Brian told me he will provide a template that includes the mounting screw holes, like cutout for the camera, and 2 holes for powering on verifying the recording light is blinking. I expect it soon. I am going to setup the camera to record when it is powered on so I only need to poke the power button with a small rod.

NateLowrie said:

I just got an un-built kit from Kevin on the yard sale for $600.:wink: Too tempting to pass up.

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I would've bought a few of Kevin's items if I hadn't just bought a boat and that was on my radar, glad it found a good home. Hope you do a build thread on it.

Oberon said:

Also a fan of "Death and Gravity", "Ultimate Ship the Second", "Frank Exchange of Views", "Lightly Seared on the Reality Grill", "Refreshingly Unconcerned With the Exigencies of Veracity", and "Just the Washing Instruction Chip in Life's Rich Tapestry".

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If I were an LSV I would be "Epitome of Ennui".

dhbarr said:

If I were an LSV I would be "Epitome of Ennui".

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Hmm, I actually don't have that one in my list. For those that are fans, I've attached my compiled list of ship names.

Nick@JET said:

I would've bought a few of Kevin's items if I hadn't just bought a boat and that was on my radar, glad it found a good home. Hope you do a build thread on it.

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I didn't really need another one considering the stupidly large backlog I have but I have enjoyed the Formula 200 so much I wanted another RW style kit. For sure I will do a build thread.

View attachment names.xlsx

It's not from the series, just a pair of words I mangled aloud having read but never heard them.

Back to the construction:
Next up was filleting the back of the rear centering ring. In the left part of the pic you'll notice the T-Nut. When I glued the plate in initially, I had to re-position the back centering ring when I first put it on and being an idiot I tried to turn it via screws I had in the PEM nut. Well, one of the nuts broke off. I didn't have much time before the epoxy set so I pulled it off and removed that nut and put the plate back on. I used a T-Nut instead but needed to epoxy it to the exposed side so that's why it's there. Should be fine. There are some anchoring screws in the epoxy to keep it from pulling out.

Next up was drilling the Av-Bay lids for the allthread. I am using 4 pieces of 1/4-20 allthread to hold the bay together. I did not feel like putting them on the CNC. I printed 2 templates from the CAD drawings and used them to drill the holes. The last pic has the 2 plates stacked on top of each other. The holes are aligned to within a 1/64, which is good enough.

Is the center hole in those av-bay lids for an eye bolt? Are your recovery harnesses going to be attached to just a single eye bolt? Or are you planning to put eye nuts on the ends of the allthread rods?

Nathan said:

Is the center hole in those av-bay lids for an eye bolt? Are your recovery harnesses going to be attached to just a single eye bolt? Or are you planning to put eye nuts on the ends of the allthread rods?

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Those center holes were there when I got the 2 bulkheads. You are correct on one side of the Av-Bay. On the side down toward the fin can it's going to be an antenna mounting hole for TRS external antenna. The main has a 10' tubular kevlar recovery harness connected to a 3/8in SS welded eyebolt through a 5/16 SS D-Link. The allthreads will have hex nuts torqued to the proper torque rating. The drogue is in the same compartment as the main. The drogue harness is 35' long and connects to an ARRD with a 2000lb rated connection that will be mounted in between 2 of the allthread holes.

The ARRD takes the initial shock load of the drogue deployment. When the main deploys, the ARRD releases the pin and the main drogue pulls the main out and the deployment bag off the main. The deployment bag sequence is a easy stage deployment that controls the inflation of the chute over a larger amount of time.

This setup I've used a few times in smaller rockets (with smaller hardware) and my TAP Fred uses frequently in larger birds. If I was doing normal dual deployment I would definitely use U-Bolts and a longer harness as the system would need to take more of a load. The numbers should be in the document if anyone wants to double check.

More pics.
Third rail button was installed. It's a PEM nut like the other 2 and secured well with an epoxy fillet. It's the white glob in the pic above. It's not ripping off unless the tube shears or the screw shears. Pardon the crappy top ring fillet job. It's functional but looks like hell.

So, I cleaned up the fillet ends and sanded smooth some areas on the fillets. It took about 30 minutes per fin to get this done for the ends mainly because I did not plan carefully enough when I did the initial fillets. You can see the front and back. Got them to taper appropriately. It good for a hand job but I need to figure out and maybe make a mold to form the set on the next rocket.

Only thing left for the fin can is one of Ravenex's camera shrouds. I was going to place it on the fin can about 10 inches above the fins in between 2 of them. I ran some preliminary numbers and asked a few people and don't think that placement will be an issue given how small the shroud it.

If any of you have any experience with placing a camera and shroud this far down I would love to hear how it went.