i had a Loc aura this past season. unfortunately it drifted into never never land when i put it up on a G80. this next season, im going to try something crazy, assuming i can make the AURA tough enough. since im attending a launch in NY with a really high waiver, i want to reinforce the AURA and make it slimlined as much as possible, and send her up on an H238. some call me nuts, i say, i know what i like, and an AURA on an H is what i like. i may also add a payload section for an altimeter. and i'll use the stock streamer cut 1/3rd the way down. since it should be durable enough for a rough landing. anybody got any suggestions? also, anyone with rocsim(im running a linux system) can you please sim this out for me? im not going for altitude, im going for speed, and i want to break 1000mph. also, i'd like to know if fiberglass will do or if CF is a necessity. i was thinking of cutting out the fins and then filling them with foam, and THEN laying some glass or CF on them, im not sure though. also, since its a surface mount rocket, i will be doing custom fins with the same pattern, just deeper, so they can reach a reinforced MMT. i think it would be really awesome if i can shoot that bird off and recover it. tell me your thoughts guys.
Loc Aura
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lalligood
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Build Aura *completely stock* using only Titebond yellow wood glue and be sure to sand airframe tube with 220 grit sandpaper so that the glue has plenty of bite for the fins. Load H238T-M. Push launch button. Sims to max velocity of 1100mph.
Lighter does equal faster. Really.
Lighter does equal faster. Really.
well, thats a possibility. once it reaches a certain velocity the fins rip off, this all occuring once the rocket is inherantly stable. lol. like a bullet. I357 would be nice, but i'd rather go 29mm. 38mm is i think how big the ID of the tube is, and i want some TTW fins on this bird. I300 would be pretty cool too. but that would also be quite unstable in my estimation.
i want this aura to max out around 1000mph, TTW fins are a must, however, i think i'll just do the foam thing, and epoxy fillets to the MMT the inside of the BT and the outside of the BT. heavy, but effective. going to need some airfoil action on those ply fins. yes ryan, it is a 29mm rocket, but there is room without the mount for a 38mm motor, it looks like anyway. i think i tried it once and there was a little drip of epoxy blocking my 38mm case from going in. even still, there'd be no room for TTW fins. i was thinking maybe of just doing this without a payload section. my original aura came out to 8oz, and that had tubs of epoxy on it. i'd say an H238 on a stock aura would push it close to the 1000mph mark.
lalligood
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I guess it would depend on where the fins rip off. With yellow wood glue, you can pretty much guarantee that there will not be separation at the fin-BT joint. And if the fins rip off in the middle during flight, there's NO adhesive that's going to help with that, now is there? That's the fault of the wood, not the glue or adhesive...
So don't dismiss yellow wood glue so quickly. Aside from the testing done over at www.rocketmaterials.com, there are plenty other woodworking websites (google for 'em) that have plenty of proof that the strongest method of joining wood-wood & wood-paper is with aliphatic resin (yellow wood glue), Titebond II in particular. And for your application/goal of reaching 1000mph with a LOC Aura on a H238, weight matters. Yellow wood glue is significantly lighter than epoxy. And just because it's less expensive & may not make as pretty fillets as epoxy deter you from trying it. Is epoxy strong enough for your application? Sure, but there are drawbacks (namely weight penalty) with using it too. Just some food for thought because I was offering you a way to easily reach that goal.
HTH,
i've had really bad experiences with yellow wood glue seperating from the BT before. one of my more treasured rockets ended up in the trash can because it smacked a tree going quite an alarming rate of speed. but hey, the fin was still in-tact. i've had NO problems other than ONE seperation upon a hard landing of epoxy. but we shall see. maybe i'll build a rocket and test it out with some yellow glue. we shall see. i dont want to risk a 50 dollar casing and 30 dollar rocket and lord knows how many hours of work on some glue that i dont trust. you know?
Don't forget to sand the tubing to get rid of all the glassine before applying *any* glue... wood or epoxy. Gets the stuff to actually stick. And yes, I agree with lalligood, the BEST glue for wood joints is wood glue.
Playing around with Rocksim a bit, there's no way to get an Aura to 1000 miles per hour with an H238T. Period. Even with an I200W you're looking at ~950 MPH, which probably won't happen either -- though it's a pretty good sim program, I've found Rocksim to be a little optimistic on velocities around transonic because of the unpredictable wave drag that happens at those velocities. You'd really need more power, like an I357T or an I300T to get you to that high of a velocity.
Also, don't disregard surface mount fins instantly. I have several rockets with surface mount fins that have held up through Mach fine, including my paper Laser/LOC 2.1. All it takes is very careful work and a little fiberglass, if that makes you more comfortable. I have a friend who has flown an Aura with an H165R (for his L1 cert flight, no less) with the stock fins held on with good epoxy fillets and a little bit of fiberglass to keep them from breaking off on landing.
You gotta bump it up to 38mm if you want to get close to that mark.
Playing around with Rocksim a bit, there's no way to get an Aura to 1000 miles per hour with an H238T. Period. Even with an I200W you're looking at ~950 MPH, which probably won't happen either -- though it's a pretty good sim program, I've found Rocksim to be a little optimistic on velocities around transonic because of the unpredictable wave drag that happens at those velocities. You'd really need more power, like an I357T or an I300T to get you to that high of a velocity.
Also, don't disregard surface mount fins instantly. I have several rockets with surface mount fins that have held up through Mach fine, including my paper Laser/LOC 2.1. All it takes is very careful work and a little fiberglass, if that makes you more comfortable. I have a friend who has flown an Aura with an H165R (for his L1 cert flight, no less) with the stock fins held on with good epoxy fillets and a little bit of fiberglass to keep them from breaking off on landing.
You gotta bump it up to 38mm if you want to get close to that mark.
oh man, thats not heartening. surface mount at 1000mph...im not optimistic about that either. especially with a 38mm casing, a 38/480 no-less being inside. now i must formulate a plot. extend the body by say twice as much, stock nose cone, no MMT, because the ID is 38mm i think. lol. only thing is, there'll be no motor retention except friction fitting. hmm. snaquin, did you use a regular tube coupler from LOC for your payload section? no reinforcement?
yeah, that stinks. i really wanted to get her goin on a cheap motor. like an H238. but since thats out of the question. i guess im going to have to go with 38mm. i have casings, i just would hate to lose a 38/480. you know? lol. the only thing im worrying about is, if i use that coupler, will it be strong enough to withstand the force laterally of a rocket cruising at 1000mph. i mean, if it hits turbulance or something. i dont want the thing to crinkle and then have a shock cord sever my entire rocket. my motor busting out and landing in someones yard 3 miles away. lol.
Then don't lose the rocket
Put a tracker in it, or fly it somewhere you can keep an eye on it the whole way... if you're flying high and fast, it's a requirement.It'll be fine. LOC couplers in 1.5" diameter are plenty strong. If you were really worried, put a wrap or two of glass on the inside and use the balloon trick to make it all nice and pretty. But the coupler is long enough that it won't cock in the airframe, which is what will shred your rocket. Make the fit nice and tight and it'll be fine.
BTW -- here's the sims reposted as .jpg since you can't read GIFs.
thanks man, looks like i'll have to go with the I357. i wouldnt want to risk the 38/480 case, and im not going for altitude, just speed, so i'd rather put it 1,000 feet less than the I300 would. I357 it is. im going to have to lengthen the BT anyway. but i'd still like to flirt around that same speed, so im going to try to keep the weight low. streamer recovery, this should be a hoot. im going to get started in probably 2 weeks. i'll keep you guys posted.
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