# Which fiberglass?

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#### Neil

##### Well-Known Member
OK, dont try to talk my out of this, you have already tried that. I have a 6" diameter (down from 8" sono-tubes) 10' tall rocket that I am planning on building, and I am wondering what you guys would reccomend for fiberglass. My choices are: 3/4 OZ (no way. Way too light if you ask me) 2OZ (I use this on most of my smaller rockets, including my MB1), and 9OZ. that is all my local hobby shop has in stock, but I might be able to get different weights over the internet, you tell me. The rocket will not be breaking the sound barrier on any motor, unless I decide to soup it up a bit when I am in my 20s, if I dont decide to retire it before then. But for now it is not flying on Ms, and an L1060GG in a few years is the absolute MOST I am going to fly in it for 6-10 years, if at all. Mostly I-K for this puppy. I know you dont think I am mature enough for these motors, but I can fly it on I357Ts to prove I built it right, and just take it up one step at a time, maybe a J350 or J370GG after the I, and then a K570GG or K550W in a year or two. I wasnt going to dive in with the biggest motor possible with my first design, but the way I worded it it kinda sounded like I wanted an L for the first flight. Big screwup there. I really planned on flying it on a J570 or less first, and then work it up. Just worded it funny. Also, how do I seal the fins so they dont come apart during flight? is there a special resin, or should I put some fiberglass on all the edges or what? Or maybe Carbon Fiber scraps from a boat-builder. Living right here on the coast with all these rivers, lakes and oceans there are hundreds of stores that would have scraps for cheaper than normal. I could proabably scrounge up enough pieces to cover the exposed edges of the fins. There is a lot of plywood left over from my parents bed (which they took apart and are planning to throw away. They got a smaller one). It is 4 or 5 ply 3/4" plywood. I am wondering if this will do for bulkheads if I cut out several circles and glued them together with some fiberglass in the middle. I am thinking maybe 4 or 5 pieces thick for the bulkhead right above the motor mount, and 2 or 3 for the rest. Since there is so much wood there (A full kingsize bedframe of it) I can take my time and if I screw up I make another one. There also has to be enough room for a good u-bolt or whatever you call those big things that screw into bulkheads to attatch shockcords to. There was one on CTulanko's L3 project, I was reading the review for it on EMRR a day or two ago. and should I make it so I can slide the fin unit out of the tube after I glue the fins onto the motor mount so I can put good filets on? Or should I do it with normal slots like LOC/presision does and just put some PML Expanding Foam in there? How does that foam work? Can I hot-wire it or use a Dremmel tool (my mom's X-mas present that i get to borrow) or a hacksaw or what? is it very hard to use? Should I glass the motor mount? what about the surface of the fins, should I glass that too? and should I put a wrap or two of glass around the edges of the bulkheads as well just to make them stronger? I need to know everything on how to do this. I know I cant do this on my own. I will have Stephen Boy helping, as well as my dad, and hopefully a lot of you giving advice. I will ask you not to tell me that I am not mature enough to do this. If I am not, at least I have two people who are at my side helping. I think I know how to make a nosecone out of foam, but it wont kill to ask how to do that too, just to see how all of you do it. What kind of glass should I use on that? And is it possible to drill or hot-wire out the part of the center of the cone for nose-weight and still have it be strong enough? What should I use for nose weight? I have som BBs, and I could get a diving weight from a diveshop. What do you use for weights? Thanks for the advice. -Neil

#### PGerringer

##### Ruler of Heck
Oooo, you are going to hate my suggestions...

First, I go to uscomposites.com and use either 2 wraps of 3oz for smaller rockets or 2 wraps of 6 oz for 6" and above rockets. It adds alot of weight but is also structurely sound.

Course if you wrap it twice with 6 oz you will have a hard time launching it on an I. 10' x 6" sounds more like an L rocket. My suggestion, if you are positive on the I and J loads, is to build 2 rockets. There is a substantial jump from I to L and a rocket made for an I would absolutely shred on an L. Unless you are talking clustered I. (if you are, sorry I missed it in the reading) Anyway, make sure you sim it out good.

Pictures, pictures, pictures...

#### DPatell

Neil - I am still not liking the idea of this, no matter who you have helping you out. a 6"x10' rocket with fiberglass WILL NOT fly on an I357T safetly, plain and simple. Maybe a J800-K1100, but definately not that I357. Use a Loc Bruiser for example. Unglassed, it will weigh about 9-10# loaded with motor. An I357 may lift it 500' at the most. Now, a 6" rocket, nearly twice the length, fully glassed, will come out to about 25-30#, believe me, I am working on one. Then you figure in the weight of adapters alone, and you have another half pound. Also, you will find that the price of an L at your age is highly unlikly. I know as well as you do that $180 is a lot for a motor, especially when thats at least 10-15 H motors! I have never flown an L, and I doubt I will be doing so for a LONG time, unless someone is kind enough to make one for me (Thanks TH) I have flown maybe 5 K's in three years of HPR, and you are in your first year AT THE MOST of flying HPR, and you only have one or two H flights under your belt. You have a lot, and I mean a lot, of research and practice to do. Can you load an H motor without needing to look at the instructions? Can you tell me the total impulse of a full I motor? What switch on your RRC2 switches from Redundant Apogee Charges to Normal Dual Deployment? These should all be off the top of your head, and if they aren't, then you have a lot of learning to do. I have said it before, I did not learn all of this overnight, I learned it over several years. Lots of practice, and I can attribute the fact that I have crashed a small amount of rockets to my knowledge and research of how my own rocket works. Ask anyone here, they all know their complex rockets inside and out. With all of that said, I suggest that you put this project on hold. The rocket is not just "I will go buy some cheapo tubes, and build a rocket." Lots of development goes into it. I highly suggest, and if I were your dad, I would require that you build a rocket with commercial tubing and nosecones and the like to build a midsized rocket, 3 or 4" diameter. 6" for someone who has never even flown an I motor is way over your head. You also have some research to do about the max liftoff weights of some motors. That way we won't have any land sharks. Spend more money, buy a nice kit, and build that. Fly a ton of G-I motors, then get your dad's L2, fly some J's and K's, then build this rocket because if you build it now, you will be ashamed when it weighs in at around 30# and you will have to get your L2 just to fly it. I have flown probably 10 J motors, 5 K motors. There are other people in this forum that have flown multiple M motors. When someone tries to talk you out of it, it's not because of your age. It's because of your experience. You have next to none in terms of High Power, and it gets dangerous when you jump in with all four limbs on your body. Take these guys advice, if you build it now, and WHEN it crashes, they will be the first ones to say "I had reccommended against it..." #### Ryan S. ##### Well-Known Member go with 9oz. I use 6oz but 2oz will not be strong enough. 2oz really doesnt add much strength and is usually used as a veil over heavier glasses so they are easier to finish. I highly doubt you will be able to fly this rocket on I motors, if it is a 6" rocket that is 10ft tall. I have a 6" rocket that is 10ft tall and it needs at least a K, and you must take into account mine will be lighter because it is made from phenolic which is: a. lighter in the first place and b. will absorb less epoxy 3/4 inch plywood is more than enough for a bulkhead. You can just put the Ubolt on the forward centering ring these rings will also make your rocket extremely heavy if you glue some together The fins wont come apart in flight. you can put some glass on them but what you really need to worry about is them coming off. The motors you have mentioned (except for the Ks) wont have enough umph to tear the fins off (unless it is landsharking, a good possibility) I urge you to rethink what you are doing here's why: a. You dont know what a U-Bolt is b. "I357 and "6 inch rocket" should never be used in the same sentence c. The statment "I wasnt going to dive in with the biggest motor possible with my first design" is a great idea in theory, however you seem to be using the biggest motor you can possibly get d. the amount of vague areas you are entering here has surpassed the limit which should be one to 2 (eg you have never used electronics before so you put them in a flight tested rocket so you only have one thing you arent sure about......time and time again people write "dont use electronics in your L2, get the cert then experiment). I could go on but I dont know if my advice will be taken here is the problem I have with this whole thing; People dont think kids can fly rockets. Why? because most thing they are immature, impacient, and stupid. I am afriad you are proving these people right. To prove them wrong you need to take you time and learn tehniques so you can do things right. When a rocket that a kid builds flies right people give them respect and realize maybe they can do it. I have seen kids tell adults what to do, and have seen them have better flights than some adult who, have been flying rockets for a long time, but these kids also took their time flying Hs, and Is (legally), and listened to people who knew more, before flying larger motors. When kids get ahead of themselves and the rocket falls to peices people think they are just stupid and out of their league it is a known fact that teenagers think they know everything hence the phrase "higher a teenager while they know everything" but you need to resist this and do what people who know more tell you, like the adults who are L1, L2, and L3 certified On another note, I have decided to build a bombproof bunker in my backyard, 15feet underground with 4ft thick concrete walls it should take a direct hit. Anyone want to come over? Should be a party #### Neil ##### Well-Known Member I asked you not to try to talk me out of this, and what do you do... Not only that but half of the stuff you said is entirely untrue. I HAVE used electronics before. And instead of finding the fact that I forget what a u bolt is a weak spot, why dont you just tell me what it is so I can make this thing that much better?? and, for the record, I am using the SMALLEST motor I can possibly have it safely fly on, not the biggest. So instead of telling me I dont know enough, tell me what it is i need to know so the rocket turns out better? That sure would be nice... Pgerringer, I will take pictures. I would take a whole lot MORE if my mom bought a digital camera.... Film will have to do untill we pay off some depts, though. Unless we get some leftovers from the sale of our current house. Then we could get a decent camera... Pictures pitures everywhere. This will most likely be my most-photographed rocket. I may have screwd up on the simulations, an I357T might not work. We will just have to see how much all the parts weigh. I will be able to do much better with Rocsim 7. Ill post a Rocsim file late tommorrow. I should have it installed by then. I believ that can do it more accurately, and then we will see. Just to make sure, you CAN fiberglass paper tubes, right? I am pretty sure you can, I saw some websites telling you how to glass a LOC paper tube. What about carbon fiber? I know of some places that would have scraps, would it be practical to use those? Thanks for the advice, Pgerringer. By the way, does anyone have a chart with the max liftoff weights for everything I-L? That would come in handy. #### Neil ##### Well-Known Member Oh, and the rocket (according to Spacecad. Not sure if I trust that program too much.) will weigh about 14#. it will NOT fly on an I357T, but an I435T would work (according to spacecad), if they are still producing them. #### PGerringer ##### Ruler of Heck LOL - We try to talk you out of it.... hehehehe A chart with max weight is a bit tough. Weight is only a portion of the flight characteristics. Length, width, shape, etc. What rocket manufacturers usually do is to sim their rockets with all the different motors so you will know the largest load for that particular rocket. Doing it backwards can be a bit inaccurate. #### Neil ##### Well-Known Member Yeah, but it gives you a ballpark idea. this rocket is your everyday 4fnc rocket, which normally would be pretty boring for me, but the size makes it better in my eye than a coplex saturn V or something. Though it would be more accurate in the max weight than anything else would be. Just thought I would ask. always worth a shot. #### Ryan S. ##### Well-Known Member dude the rocket is going to weigh more than 14 lbs you will be lucky to be able to fly this on a J motor #### Neil ##### Well-Known Member How much more, would you say? as I said, I cant really trust SpaceCAD. I had already added about 6-8 pounds to what it origionnaly said, but I guess that is not enough. How much do you think it will weigh? #### DPatell ##### Well-Known Member 25-30# My dad's 4" Bull Pup, with no glass, is 11# on the pad. My Magnum, with no glass, is 14# on the pad. My 7.5" that I am working on, the bottom section, about 36" tube glassed with 4oz., is about 8#. My Der V3, using 6" quicktube, without nosecone is about 6#. With motor, electronics, chutes, glass and everything, expect anywhere from 20-30#. You're in the full J (at the very least) to small L territory. Remember also, the reason that I am trying to talk you out of it is this: You represent young rocketeers as much as any other young rocketeer does. DaveyFire, RocWizard, Ryan S., Blue Ninja, and any others from the forum are represented by you. I don't want to see this thing fly due to lack of experience and have something go catastrophically wrong. It would in turn reflect on us. We try our hardest to give young rocketeers a good name, please don't do something that may endanger that. #### Neil ##### Well-Known Member I am going to be flying this in what is most likely the least-advertiesed club in the world, if something goes wrong there practically no one hears about it. Heck, if somethin goes right no one hears about it. There are about 12 people at the launch, only two of which (me included) are members of TRF, the other has only had 6 posts, and I doubt he would go trupeting it even if it DID crash, which it will not, if I build it right, and with the SUPPORT of people here, and the continued support of other people who know me. I am not trying to kill rocketry, dont worry. I have to run now (wish I didnt, but my parents are making me). Ill argu... er... debate later. #### PGerringer ##### Ruler of Heck Originally posted by Neil and I doubt he would go trupeting it even if it DID crash LOL, now dont be hasty. We want to see pics good or bad. Course we would prefer good, but we will laugh with you if it is bad. And, of course, it is good to laugh... hehehehe #### daveyfire ##### Piled Higher and Deeper TRF Lifetime Supporter I've got a 6" x 10 ft rocket that is 42 lbs loaded with an M1419W... that puts it at 30 lbs unloaded. You'll be lucky to get this in the air with a K1100T. Recovery systems (especially tubular nylon), epoxy, and fiberglass add a whole lot of weight. Is SpaceCad including the weight of your chutes and TN? If not, a fully loaded 34" piece of 6" glassed phenolic with 100 ft of TN, a Rocketman R7C ProEX, and a Rocketman R14C weighs 6.3 lbs. Add that in, plus about 2-3 lbs per tube for glass. Don't forget epoxy and other miscellaneous assorted items. On this 6" cardboard rocket, I'd suggest 2 wraps of 6 oz. cloth with or without a sanding veil. You'll need some strength for this airframe because SonoTube is pretty weak. You could try carbon, but at that point you'd be better off buying 6" fiberglass tubing price wise Hope that helps some. And remember, K1100T... K1100T... K1100T... #### Neil ##### Well-Known Member This keeps getting heavier.... Maybe I will ask the tube company if they have a slightly smaller size... Maybe 5" or 5.5" that would make it just a little lighter. It would be going just a LITTLE faster on the bigger motors, though. Not like I dont have plent of time to plan this... OOOO, maybe this new email I got is from the other tube company.... Nope. another virus. they dont do anything, but I swear, they account for half of my mail. It is all this WormEKlez bug. Anyone else having problems with this worm? It has a lot of emails called "have a happy chritmas" and other random things it picks from a list. Very annoying. #### Neil ##### Well-Known Member Here is a Rocsim file of the scaled-down rocket. About 5.25" in diameter, I think. #### DPatell ##### Well-Known Member I can't seem to open the file. It gives me the "There is an offending part, it has been ignored" window, and then it bombs out on me. Anyone else having this problem? #### Neil ##### Well-Known Member Thats strange.... are you using a mac or PC? #### rocwizard ##### Well-Known Member I notice that every motor you simmed tis on is either a K or an L, with the K getting it to barely 2000 feet. Rocksim rarely also gets the weight right, rockets will ALWAYS end up heavier when they are finished then what Rocksim shows. As it was, it showed it being 25 pounds. #### Rocketman248 ##### Well-Known Member I took a look at the rocket. It looks pretty cool. Can I offer a suggestion? Make the fins a little smaller. The root cord length is quite long. On my L3 rocket, the length was 30 inches and it was just too unweildy. Also, big fins are heavy. #### Neil ##### Well-Known Member I ALWAYS make the fins in my simulations too big. Funny litte quirk. Here is a sim with smaller fins. just a little less stable. I found a paper tube company that stocks 36"long 4" diameter tubes for$1.30 each. I may consider buying a full pack of them (15 tubes) and make a lot of smaller designs with 54MM mounts. Ill post some sims. The fins are proabably too big.

BTW, I added 5 or 10 pounds to what Rocsim said. I may or may not go with that design. a lot of smaller 4" diameter birds is looking like a mighty good idea to me now that I see I cant fly this thing on anything less than a K.... I just want to hear back from the company that makes them... Edited in: I mean the company that makes the tubes, not the motors.

#### Neil

##### Well-Known Member
BTW, suggestions are greatly apreciated. Especially if you have built rockets in this manner before. Thanks. Here is a 4" diameter sport bird I whipped up. It has TTW mounting, you just cant see it because of the centering rings are in the way.

#### Neil

##### Well-Known Member
Anyone know of a way to post multible .RKTs in one post? that sure would simplify things...

This design is the same as the last one, only it has a 36" payload bay so I can use altimeters, and I might have put in a bigger motor mount, I forget.

How much do you think a 5" diameter rocket would weigh if I built it like in the simulations?

#### Neil

##### Well-Known Member
Heres one with smaller fins. well, thats the 4" one with smaller fins, I already showed you the big one.

#### havoc821

##### Well-Known Member
I'm glad you backed away from that 6" design. Sounded like a cool rocket but NO J motor will get that rocket in the air by the way you want to design it. 4 inch rockets are cool, so build one then go from there. As for me, I am building a 4 inch rocket, 9 ft tall and it will probably weigh 10 pounds in the end and I built it as light as possible. It is 8 pounds now and that is without foam on the inside and fiberglassing the fins. I have run into the same problem as you. You have to PROVE to people that you are capable of doing this. Here is an example that someone gave me:
It doesn't matter how old you are, if you are some new guy at a launch that no one really knows and are wanting to fly a big motor they are most likely going to say NO. Within your club, fly an H or I flight and prove you are serious about HPR and photograph and document construction techniques and get someone who is certified to vouch for you to say that yes this rocket was built good and can handle a J motor or whatever. That is what I am doing with my HPR rocket. I will fly and H at the next launch and try to get some support for this project and I will make a folder with pictures of how the rocket was built and get a friend in high places (for me it is Chuck Andrus) to explain to everybody else that I am capable of doing this. I am getting a lot of help by Chuck with this project and probably couldn't have done this without him and I will be doing a lot of firsts with this rocket, example: electronics, big motor, HUGE rocket, fiberglassing, etc, but the only rason why I feel confident that I can do this is because I had HELP!!! You have to get help by others. Anyways, I hope this helped and good luck with the project.

#### Neil

##### Well-Known Member
I am lucky in that sense. I have a VERY smart L3 guy helping me along the way, and if he tells someone it was built right, most likely they will let me fly it. And I am not building 1 4" rocket, I am building 10 or so. Not all at once, but one after the other after the other. I plan to have a 4 29MM cluster (I want to fly it on dual G64s, and have another pair of mounts in case something happens to the other pair), single 38MM, single 54MM and single 54MM with 18" payload bay by the time I am through with this. Proabably two of each. a boiler-plate and a final version. That way I have a backup. If an ejection charge fails or something or a fin breaks, I can just fly the boiler plate version. I am also going to make a couple half-scale models just for the heck of it. Not like these tubes cost more than a buck thirty each or anything!!!

I am comfortably sitting in our brand new house right now. Our cats have been here a good 36 hours and are pretty well settled in. The rest of my rocket stuff is being moved in as we speak. I am VERY exited. I have to go help now, so bye.