L1 Cert choices

If you’re opening up to the idea of flying Gs single deploy (which I think will be much simpler and less stress)...

Build the dinghy first.

The Optima is an Estes rocket from the mid 90's.

SARG has the bigger rail pad, and at least one longer rail for the smaller pads. They don't usually use them at Gibson Ranch, though.

One benefit of a JLCR is t so much avoiding using BP, but being able to do DD out of a single break in the airframe.

A cert rocket just needs to go up on an H and land intact.

I wanted to mention that I think JLCR is one of the greatest innovations for model rocketry in recent times.

The Nike Smoke caught my eye and may be in the long-term lineup.

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A funny thing happened this Saturday. Curious, as a funny thing happened last Saturday and turned out great. Today was even more random.

I suppose only a few of you know the next SARG launch is 24 March, while most of you know today is 17 March. I didn't. I drove up to an empty Gibson Ranch where the gal at the gate told me there were no rockets today. I realized what I did and decided to go to R/C Country Hobbies. We're lucky to have such a good LHS nearby! I've known the owners 25 years or so, and for some reason Terri was near the front door. She said Hi to me and asked what I was in for today. "Do you have any big rockets?" She knows me and had a good idea of what I'd want, and walked me to the rocket section. "Here's our largest diameter" - pointing at the Estes Nike Smoke.

I checked at the counter. They had four G40-7 motors. A quick trip home, found the Rocksim file, and a G40-7 looks great. Apogee is 1050', off the rod at 52.4 FPS, optimum delay 5.78 seconds... the rocket is light for its Cd so it doesn't speed up much over the top; the 7 second delay results in 35 FPS at deployment. And... tada... an H55W-6 hits 2100', off the rod at 54.3 FPS, deploys (1 sec early) at 35 FPS.

I bought the Estes Nike Smoke and two G40-7's. I can fly the L1 cert flight with this rocket.

I can have it built by next Saturday and fly at SARG rather than just watching. It doesn't need a rail.

I'll be getting a JLCR as a matter of course now. No problem finding it from 2100' with a CR.

I got a missile.

What an odd way for this to turn out! It's also great in its own way. I can research the more expensive rockets, decide what I want, build the next one well, and don't need to spend the whole wallet at one time. Go figure.

Well, not technically a missile... It's a research rocket that was later adapted into missiles (or the other way around? not sure.)

Either way, I've heard pretty good things about that rocket... It's a common L1 rocket (at least around here- I know of one person at my relatively small club who used it). However, finding an H55W may be a different story- they seem to be out of production, and I'm not sure whether you could use them for a cert- I'm notsure whether they're still certified.

If you're going to be flying HPR more than occasionally, you'll probably want to get into reloads anyway. The CTI H54 White Longburn is pretty similar to the H55 and only sets you back $50 for the full 1-3 grain hardware set. Aerotech doesn't have too many slow offerings, but if you build solidly that rocket should be able to take an H128W just fine, and most Aerotech loads are HAZMAT free.

Well your sim numbers look real good. There's way worse kits to cert with. Many people have tried the L-1 with Estes on a small H. It's a valid method when the kit is built better than just for LPR/MPR motors. Snarkl had a thread on converting an Estes kit. You may want to beef up the epoxy application or choices or add a bulkhead depending on how it feels. Some have converted the Estes Patriots on YouTube. The Nike is a classic forum favorite.

When I flew an HPR motor they made us have 1010 rail buttons for the launch rail guides. But as long as SARG has a rod that has ground clearances meet safety code then it's all good. Usually the HPR launches have 200ft or more of standoff distance. Funny how life turns out. I think you will be successful. The larger diameter has more drag force and slowed your kit down which is less stress on airframe. You'll easily have visual the entire flight. You made a good choice I think.

You'll do fine with a Smoke on a baby H (H128/H165 reload, H115 SU) at Snow Ranch w/o a JLCR. There's PLENTY of room to hike. When I did my L1 there with a Leviathan I ended up walking a ways up on the ridge because I wanted a "safe" landing/recovery and put a 28" chute deployed at apogee. Didn't mind the walk, not a scratch on the rocket. You'll do fine...

LithosphereRocketry said:

The CTI H54 White Longburn is pretty similar to the H55 and only sets you back $50 for the full 1-3 grain hardware set. Aerotech doesn't have too many slow offerings, but if you build solidly that rocket should be able to take an H128W just fine, and most Aerotech loads are HAZMAT free.

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Loki has H-I 38mm loads no hazmat by the way they pack the fuel grains into smaller pellets but not CA legal. When you hit Aerotech 38mm-480 loads they all have hazmat. If SARG ever has a motor vendor you can dodge hazmats. CTI generally always has hazmats due to the way the pellets are preloaded. You may assemble Aerotech hardware and reloads ahead of cert date. The RMS reloads allow you to inspect everything for cracks or defects and this may save your rocket but many complain of under a dozen pieces you basically insert into a casing by a instruction manual. It's not hard. If you go with Aerotech hardware get a bottle of Superlube for the o rings from hardware store it'll go a long ways. You add the deploy charge to the motor eject on AT over the delay grain then 3m compress tape over the charge well. On CTI it's in a black cylinder with 1.2G and you may have to reduce charge to not blow apart a tiny rocket. The SARG Guys will sort you out on deploy charges the day you fly if you need help. I had a local flyer tell me the white disks in a AT reload that go over the ejection charge well were "worthless" and 3m blue tape pressed by finger around the top but not touching casing sidewalls worked better.

the CTI 24mm and 29mm hardware has metal rear closures. I prefer any casings with metal rear closures over plastic. The CTI 38 had plastic so I bought AT 38 hardware. The AT hardware has thicker casing walls. Either brand will fail when the phenolic liner has a defect by thermal failures. Metal elastically deforms predictably in engineering terms.

Andrew_ASC said:

Loki has H-I 38mm loads no hazmat by the way they pack the fuel grains into smaller pellets but not CA legal. When you hit Aerotech 38mm-480 loads they all have hazmat. If SARG ever has a motor vendor you can dodge hazmats. CTI generally always has hazmats due to the way the pellets are preloaded. You may assemble Aerotech hardware and reloads ahead of cert date. The RMS reloads allow you to inspect everything for cracks or defects and this may save your rocket but many complain of under a dozen pieces you basically insert into a casing by a instruction manual. It's not hard. If you go with Aerotech hardware get a bottle of Superlube for the o rings from hardware store it'll go a long ways. You add the deploy charge to the motor eject on AT over the delay grain then 3m compress tape over the charge well. On CTI it's in a black cylinder with 1.2G and you may have to reduce charge to not blow apart a tiny rocket. The SARG Guys will sort you out on deploy charges the day you fly if you need help. I had a local flyer tell me the white disks in a AT reload that go over the ejection charge well were "worthless" and 3m blue tape pressed by finger around the top but not touching casing sidewalls worked better.

the CTI 24mm and 29mm hardware has metal rear closures. I prefer any casings with metal rear closures over plastic. The CTI 38 had plastic so I bought AT 38 hardware. The AT hardware has thicker casing walls. Either brand will fail when the phenolic liner has a defect by thermal failures. Metal elastically deforms predictably in engineering terms.

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I'm a big fan of Loki too, but the Estes PSII Nike Smoke is 29mm...

Rockethound said:

I bought the Estes Nike Smoke and two G40-7's. I can fly the L1 cert flight with this rocket.

I can have it built by next Saturday and fly at SARG rather than just watching. It doesn't need a rail.

I'll be getting a JLCR as a matter of course now. No problem finding it from 2100' with a CR.

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FWIW, I did a very similar thing for my L1: Mammoth, JLCR, H97. I taped over the leading edges of the clamshell fins, but that's probably just paranoia.

Good luck! I built mine entirely in my popup at Airfest, so I know you have plenty of breathing room

LithosphereRocketry said:

I'm a big fan of Loki too, but the Estes PSII Nike Smoke is 29mm...

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I kicked the TRF hornet nest on the 29mm H Loki topic. Whether Loki wants to is a whole other thing.

Loki does not not apply to the OP. He is in California.

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This is an EXCELLENT choice.

Lots of 29mm options for L1. Built stock, that kit will fly on any 29mm L1 motor you can put hands on. There's a few things you should likely change, and that advice will come fast and furious from those that have built them.

CTI- H133BS AT- H238T either would be a nice ride

DavidMcCann said:

This is an EXCELLENT choice.

Lots of 29mm options for L1. Built stock, that kit will fly on any 29mm L1 motor you can put hands on. There's a few things you should likely change, and that advice will come fast and furious from those that have built them.

CTI- H133BS AT- H238T either would be a nice ride

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You sure about *any* 29mm L1 motor? I bet an H399 White Thunder might give it some trouble... It would be quite the show though!

I suppose that building it for L1 cert makes it a research rocket. Such as using an H55... and thus I learned that OR's motor list isn't up to date. I wonder what else is gone, and what new replaces it? CTI is looking like my preferred reload option right now, and since Mike at BAR will be at LUNAR I can get them from him.

I prefer to use rail buttons. I'll order them and come up with a standoff for the NC bulge. But that means swatcat will have to drag the rail out to Gibson Ranch - is that reasonable?

I also plan to get Kevlar cord for harness and shock cord. "Elastic is for underpants" and can make the NC snap into the fin can. Probably will get a coupler to help mount the harness and reinforce the BT. Fill the fins with Bob Smith 20 minute and micro-balloons to make them strong and resilient. The fins bow so that when you compress the middle, the edges are in first contact. It can all get nice and flush with a spring clamp and wood. I need to make sure the fins don't react to denatured alcohol, as that's how I clean damp epoxy from FG and plastic.

The slotted CR that mounts the fins is too large to square up on the motor tube. I'll have to tack it into place in the BT using the other two CRs to align it, then pull it out and fillet it properly. So I'll build the fins first, then they can brace the slotted CR into its best position when it's tacked down.

The nosecone hard point seems flimsy. I'll probably put an eyebolt in it, especially with Kevlar.

Eric - before I started this post, I was thinking that the cert flight should be DM or Skidmark. It merits the fireworks. I saw you made the same choice. Right on! Do you think a H123-SK-9 is a good choice? Sim says 1738', 75 FPS off rail, 35 FPS deploy. Seems perfect!

This is an EXCELLENT choice.

Lots of 29mm options for L1. Built stock, that kit will fly on any 29mm L1 motor you can put hands on. There's a few things you should likely change, and that advice will come fast and furious from those that have built them.

CTI- H133BS AT- H238T either would be a nice ride

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Hey, thanks David! Funny how I was led into it by circumstance. And you offered another CTI recommendation. I'll see what's at BAR and learn the ropes. SK or BS? That is a question.

I bet an H399 White Thunder might give it some trouble... It would be quite the show though!

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Apogee 2317' max vel 826 FPS. Delay timing at 9 sec is spot-on perfect.

Only 52G, no problem at all.

You can check the thrustcurve.org and edit preferences drop those files in a .zip then select directory and go! A bunch of Aerotech DMS loads are missing which are single use carbon fiber type casings where you don't buy the hardware so it's cheaper to cert on.

75 fps off rail is decent on skid mark. In general anything excess of 45fps off launch rail at 1.5-2.0 Stability cal is great. Then it's up to matching delays. If you're a second off don't fret.

Rockethound said:

Only 52G, no problem at all.

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I was only able to track a FCC grade TeleGPS to 60.6 G's. That wasn't in a book anywhere. I know you aren't using GPS yet but someday when you do there are limits. The first HPR launch I tried had 168G's and battery disconnected. Just rambling a tad to give you insight to how electronics can fail. The ublox chipsets on GPS were rated to 4-7 G's officially but unofficially I found I could track higher than rates G's. And an Aim Xtra brags of 105 G's.

Rockethound said:

SK or BS? That is a question.

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Skid any day, at least for me... The only issue is the 1-3G starter kit won't help you much- the 3 grain skid is a G. The H123 would be a nice L1 motor though... If you're REALLY confident in your building, you could consider this one:
https://www.thrustcurve.org/motorsearch.jsp?id=712

6XL skidmarks- can't get much better than that (or louder)...

I've heard in certain skid mark loads AT and CTI one failure mode is if the igniter isn't at top of fuel grain it'll just burn on the pad. What was explained to happen is the igniter can catch on the fuel grain spacings if not fully inserted then it burns like a road flare unable to generate enough pressure to leave pad. They generate a lot of sparks for visual effects. Perhaps a classic CL is more dull. My USRC team CATO'd a H123 Skid last year but I'm not blaming CTI.

I've heard in certain skid mark loads AT and CTI one failure mode is if the igniter isn't at top of fuel grain it'll just burn on the pad.

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Road flare. Read about it. Talked to Mr G about it. It's on the checklist for any motor - "is the igniter all the way up?" Bend and tape it at the bottom, loop the wire on something fixed.

6XL skidmarks- can't get much better than that (or louder)...

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People here do push the envelope at times! I am probably Tripoli at heart. But really, LR, is it reasonable to expect an Estes cardboard BT to endure 32G's ? It sounds like a disassembly waiting to happen. I can fillet fins, make the bottom end real strong, but the BT?

I wouldn't put a 6XL in an Estes. It's pushing it to use a H motor! Of course I was the "nut" to drop a AT 38-480 i1299N-P into a first scratch two stage predicting 20k ft with half a tube wall sanded off, it made 2,500ft a slight echoing boom M1.5 plus and disassembled at 2,500ft interstage piece between two rockets had failed. Nobody had a thread on 1299 multistages. Vanishing act was one on here that never recovered by G load. I saw it matched a K class thrust curve. I basically wanked to other comp teams and was like don't use that WarP 9 Orbital Pegasus fincan fuel it wrecks sh*t here's are broken pieces from Utah. They Lol'd at the pad you want more burn time buddy not thrust! I had zero clue that first launch. Designed some pieces in cad too thin. Only had a 0.3s burn but 1500N. Eats rockets under 2 pounds I swear. Then somebody said they loft twenty pound birds on a H699 and I really blushed. What I'm getting at... There is something as too much thrust. You can get higher Alts with longer burns on a second stage or a milder booster for stages.

You are really smart to ask. I didn't ask that first time then was like holy cow little aluminum can has hella thrust! My nosecone design was thin wall but it survived had a real low Cd. The tube sheared. Madcow never had a tube diameter so we rolled with prelim numbers and well. It's bad when you disassemble CF on a L-1 motor.

Fill the BT with epoxy coated couplers. Or glass it internally.

I mean, no.... that’s a dumb idea don’t do it loo

You might be able to fill the nosecone with epoxy. I can tell you a 30mm nose at M1.7 had 40 newtons of drag but at uni I had access to people that could CFD. Shoulder cracked so we made it thicker next flight. So the drag force depends a lot on velocity squared, cross section area, drag coefficient, and fluid density divided all by two. We like you didn't know when what G or force was too much as engineer students. Cd value is hard to predict in theory. Need wind tunnel at Mach of it predicts in sim or ask about CFD of cad of rocket. That's way too theory crap for this L-1. Took a prof three weeks when I had a solidworks computer model of entire airframe to get one number for one drag force equation.


Basically Open rocket gives you a Cd value it's sorta wrong because it isn't "advanced fluids dynamics accurate" but it's less wrong than you guessing a cd value. So maybe it's 10% off. I don't know if a cardboard could take the force it encounters from drag in flight but I assume it's CD value is high and the actual force at lower Mach is low. So if you knew the air density at max Mach alt, area of tube diameter assumed as circle, max velocity of model you could get a force on that that cone using the OR cd value. I think OR will excel output a drag force too in excel. For your intent and purpose it's right because that other uni design route is too much of a pain in butt.

Then you could try to crush the cone with a mass*gravity equal to the predicted drag force. The problem is it's a distributed pressure over the surface not a point load. Ughhhh. Normally computer models FEA. Or the practical route is reinforce or cloth/resin wrap the bt with your fiberglass skills. A lot of people try to overbuild stuff here or ask when crap fails practically because even the theory routes don't always work in reality. Sorry for a long winded rant. I don't know practically if a bt survives because I never tried cardboard bt on an H the other guy said his worked. It's harder to solve that in theory with math. And I lack common sense much. It's hard to know without flight test.

heres more stupid ramblings... If you had the nose in a jello like substance you could apply the force and it would transmit that force to the entire surface area of the cone as if it was a distributed load. Which is completely useless for an L-1 rocket kit. I would say water but water ruins cardboard.

Open Rocket, RocSim, and RAS Aero and RAS AeroII are all most rocketeers will ever need, including most of the college teams building stuff with hobby component parts. CFD analysis, FEA while nice to have access to does the average rocketeer little good. Generally if good info is put into the hobbyist accessible programs its very easy to get inside of 10% accuracy on the sim, which combined with air pressure, wind, temperature, motor variance, and other factors is usually about as accurate as we need to be, while dead on is nice motor to motor variance alone can cause a 10% sim variance.

By now everyone is aware Andrew of just what your college team has done, and how it did it, your beating a dead horse ( I expect DizWolf will be along shortly with the proper graphic for the beating a dead horse)

I'm going to be honest on an engineering team some of the data felt useless to us as senior students. We had stuff fail in ways we did not predict. Sim says whatever reality kicked us hard. Nose shoulders not profile. Somebody asked if a cardboard nose fails. I think OR is accurate enough for a drag force and an actual test of the cone in some kinda of fluid/gelatin with a simple mass using gravity equal to a drag force is adequate to test crush it on ground by an rocketeer in an experimental way before flight. Which is nonsense but may answer if a cardboard cone would survive X drag force at Y Mach number at Z alt. Most people will say it crushes and it's safe to assume they are correct.

When somebody asks structural questions the general answer is overbuild it but how do we even verify we built it strong enough??? Wouldn't it be nice to Toss the CFD\FEA aside and actually test it for a certain drag force before it meets that force? Compressible flow happens over Mach 0.3 in theory land and I doubt the force would translate as well. You could test a force in one direction but in actually it has many forces and components. And I'll just shut up. Sick of nosecones and crap breaking in rockets dude.... Even when you have a FEA it ain't magic.

Andrew - it's just an Estes model rocket. It's rated by Estes on the packaging for a G80, which gives 12G at its stock weight (G's will be going down as weight increases in my strengthened build). So I'll limit the cert flight H motor selections to 10-12G and find a long burn. It's a cheap kit, no lives depend on it, and maybe one day I'll overstress it. Doesn't matter.

• AT G40: 1050', 7.7G's, off rail at 52.4 FPS
• AT G80: 1260', 12G's, off rail at 67.4 FPS
• CTI H54: 1765', 10G's, off rail at 62.4 FPS

Honestly, you can't sim thermal lift or downdrafts the way they'll be on the day of the launch. OR gives me a comparison tool; its absolute accuracy is +/-10% based on posted results. That's good enough. It kept me out of a 6XL. I thought about CA'ing 4x 2mm CF rods down the sides of the BT from base of NC to the MM. Very light weight but adds a lot of strength.

I finished one fin last night. Weight without glue: 28.2g. Weight after stuffing its innards with epoxy/microbubbes: 43.2g. Increase in weight is 15g per fin. Increase in strength is 20x. These fins won't flutter. I took pix and will probably start Yet Another Nike Smoke Thread. Oh... after making the fin description proper in the OR file and setting the weight to 48g/fin, then adding an eyebolt on the NC, the figures are safe'n'sane.

• AT G40: 942', 6.3G's, off rail at 48 FPS
• AT G80: 1217', 9.7G's, off rail at 61 FPS
• CTI H54: 1756', 7.1G's, off rail at 54 FPS (1756 is not a mistake, almost the same as above)

Gents, how do I get an RKE motor file from thrustcurve.org into OR?

You need either a .eng or .rse file, simply go to Edit>Preferences>General (first tab, should be open)>click Add>browse to file location, click on file name and accept. Next time you open OR the thrust curve will be available.

If it hasn't been mentioned already make sure the leading edges of the Estes PSII Nike Smoke fins are sealed, otherwise they can open up under flight pressures and shred, some people have used clear packing tape to seal the leading edge after painting.

Oh, RSE... right. Thanks for the instructions.

I made a couple jigs to hold the edges together. Slotted some thin wood on the sliding compound miter saw.



The Bob Smith 15-min epoxy/microbubbles compound got squeezed out of all the edges so I know they'll bond. Push the halves together, wipe off epoxy, repeat until epoxy starts to cure. Clean it all with denatured alcohol... then start clamping the ends and squeezing the jigs. Remove it all, clean with DA, repeat until the heat is reducing. The polish the whole surface with DA so it looks like it did NIB. This edge won't come apart. By using DA along the way, there's no sanding required.



I'll have more photos in the YANST (Yet Another Nike Smoke Thread...)

That will work great for an L1. Stick an H115DM in there and be done with it. In almost done with my PS-II Smoke build as well, just working on paint. I assembled with 15 minute BSI and did beef up recovery attatchment. Put a nice epoxy fillet on the fins. I wouldn't hesitate putting a smaller H in it. My CA built Argent handled an H115DM and H195NT.

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What JLCR failures I am aware of were due to pilot error, not the unit. It’s a very simple and robust unit that works very well. I genuinely enjoy using it but then again it fits my simple seeking mind.

Sorry I apologize for getting off topic. I think you make the right move to lower the G limit. Even if you shredded it, there's no major loss just your time and effort. Have fun with your cert and build.