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marshall1031

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Hello all, I'm just getting back into rocketry after about 5 years. I have never been into high power rocketry, but just recently I have become very interested in it.

I just ordered a custom 4" Armageddon kit from DGA that has a 75mm motor mount instead of a 54mm. The question is, do I need to fiberglass this rocket because of the oversize motor, or will it hold up ok? I have never used fiberglass, so I don't really know when and when not to use it, but I am definately ready to learn how it's done. Does anyone have any recommendations as far as choosing a type of paint for my project? Like I said this is my first high power project, so I'm in the dark a little, and any help is greatly appreciated. :D
 

BlueNinja

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Whoa, 75mm for a first project? I dunno, but what I do know is you have to certify high power before becoming able to use H-> motors. it goes : Level 1 for H and I, L2 for J-L, and L3 for M-O. I don't think that you could certify L1 (which you have to do in order to get L2) with this rocket. I think 75mm is too large for H or I.

Now watch somebody come in here and correct me:p.
 

marshall1031

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I wanted to get a 75mm mount so that I can use adaptors for smaller motors, then go bigger when I can. Could I use the same rocket for more than one certification?
 

swimmer

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Marshall,

Look at EMRR motor recommendations for the 4" Armageddon. Then, look at the EMRR reviews and pick out someone who has built an Armageddon. Email them and ask them a lot of questions before you start. Also, look at the flight logs for this rocket. Lots of good info.

If you are using the Armageddon for TRA L3 check out the L3 filing instructions before you start construction. Doing what is required may put you over the weight limits for H-J motors. The Armageddon is 4-6 pounds, according to DG&A specs, and yours will probably weigh more when finished.

Do you have a LEUP? L1, 2, or 3 certified? You will have to be to fly HPR at a TRA sanctioned launch. Do you have a LEUP or LUP from the BATFE?

The Armageddon is a great rocket and one of my favorites. The Armageddon is ambitious, however, after you being out for 5 years and never flying HPR. Go slow, do a lot of research before you start.
 

mshaner

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I'd have to agree with the cautions mentioned above. Regardless of whether you are certified L1 or L2 this type motor mount is going to get you into altitudes that you don't want to touch with a single deployment method. Dual deployment is whole set of issues within itself so I leave the topic here.

As for the weight of 4-6 lbs - I can tell you from experience that you're rocket will be considerably heavier when it's all said and done. This is especially true IF you still decide to go with the 75mm deal. Lots of extra measures.

As for the glass - my opinion is this. You CAN fly an M on in a phenolic PML tube, BUT how long? Secondly, and only in my opinion, glassing is not so much used for structural issues but for the sake of rebuilding should deployment or other things fail. I guess longevity is a larger concern. Before I get bashed - structural integrity does play a role too - engineer-type :D


Soooo, in conclusion - it's very good that you're thinking long term and versitility, but at this point it would be like taking on Everest just because you have $75,000 to throw away. There's alot of cool peaks in between the grand poopah of mountains/rockets. (mountaineer too) Augh! Too many hobbies and not enough time:(

Shane
 

marshall1031

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I don't even have my level 1 certified. But I want to build this kit, should I go for it? What is the maximun weight to get my level 1 certified? I am going to use dual recovery, but is this kit too large to get my level 1 certified, even with the 54mm mount? I will do whatever I need to work my way up to level 3, I just want to get there with the least amount of money as possible, hence building less rockets. Thanks guys.
 

eugenefl

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Greetings Marshall! Welcome to The Rocketry Forum!

I just wanted to add that none of these gentleman are trying to discourage you nor flame you. (None of that ever goes on around here.) Actually, I can appreciate that you are being ambitious in your approach to rocketry, but to reiterate what has already been said, take a step back and look at your approach a little bit more logically. It's kinda like going to a buffet and scoping out everything offered before committing to piling on the plate. Sometimes early in the meal your eyes are bigger than your stomach and later you find out you're too full to enjoy the good stuff. My analogy has its similarities to rocketry, but in careful observations of the previous replies made, I can see that these fellas are just looking out for you. Mistakes in the upper spectrum of this hobby can be very costly and more importantly, dangerous. Does these mean pack up the kit and send it to me, of course! :D j/k Really though, ask a few questions and then attack it with a jar of tartar sauce. Best of luck in your quest for extreme rocketry.

Once again, welcome aboard. We're glad you're here!
 

marshall1031

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Thanks, that's a good analogy. Did I choose the wrong kit to start with however, or can I use it to get my level 1? Do you have to use a different rocket for different levels of certification? You see what I really wanted to do is build a rocket that would work for levels 1 and 2, then build a 5.5" Armageddon to get my level 3. Do rockets need to be checked out while being built, or when finished for certification? Sorry I'm so confused everyone.
 

eugenefl

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Originally posted by marshall1031
Thanks, that's a good analogy. Did I choose the wrong kit to start with however, or can I use it to get my level 1? Do you have to use a different rocket for different levels of certification? You see what I really wanted to do is build a rocket that would work for levels 1 and 2, then build a 5.5" Armageddon to get my level 3. Do rockets need to be checked out while being built, or when finished for certification? Sorry I'm so confused everyone.
Ah, no worries about the questions or confusion. I had a hard time learning that "tying the shoes" thing back in the day. ;) This isn't all that more difficult. It's just a lot of information all at once. I can see you are eager, so digest it a bit a time.

At any rate, I'm uncertain as to the specs of the Armageddon, but the rules of certifying L1 are pretty straightforward. For the in-depth "rules" regarding L1 certification, check out the NAR <a href="http://nar.org/hpcert/NARhpdetails.html">HPR Certification</a> guide. The short version is this (taken from the NAR website) - "The modeler must demonstrate his ability to build and fly a rocket containing at least one H or I impulse class motor." The rest of the rules outline who must be present to witness your flight and sign you off, the particular "form" you must fill out (which looks just like a basic 1-page application), and other misc. details. Not too bad at all.

When built properly, most Level 1 rockets are Level 2 capable. Level 2 isn't much different but it also adds a new element - a written test. (I have heard of people certifying both L1 and L2 in the same day.)

Level 3 is the more difficult to obtain. I'd like to say "cross that bridge when you get there," but since you've asked I will refer you to the NAR website once again.

SUMMARY:

Join the <a href="http://www.nar.org/">National Association of Rocketry (NAR)</a> or <a href="http://www.tripoli.org/">Tripoli Rocketry Association (TRA)</a>.

LEUP - Look into applying for a BATFE (Bureau of Alcohol Tobacco Firearms and Explosives) LEUP (Low Explosives User Permit.)

While under supervision:
L1 - Fly and recover an H or I powered rocket safely
L2 - Take and pass a written test on the principles of rocket design. Fly and recover a J or higher impulse powered rocket safely.
L3 - "A whole 'nother can of worms" LOL...this isn't my specialty since I haven't researched it.

Not sure if you've been to this site, but you might want to check out http://www.flyrockets.com

Hopes this helps you some.
 

Rocketman248

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I say, fiberglass the heck out of it. Build it like a rock. Then get something smaller for your level one. I'd recommend a PML Tethys. Fly the Tethys on an H to get your level one, then fly the Armageddon on a K or something.
 

marshall1031

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Alright, thanks a lot for that info guys. I'm gonna go ahead with the Armageddon w/ the 75mm mount and see what I can do. Now, as far as the Armegeddon being to big, what if I used a motor adaptor so that I could fly it first on an I motor, would that be a good idea for level 1?
 

mshaner

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I along with the others certainly do NOT intend to deny you the building of the proposed beast. So build on...we do, however, want to see big grins when you see this puppy come down softly as others stand around and congratulate you. So sorry if my previous post came off harsh.

Now about launching an I in this rocket. Let's say that your rocket comes out to weigh around 8 lbs by the time your finished (including the motor & adapter). You can use a ballpark 5:1 ratio figure to see if your going to be safe.

Here's how it works and I've attached a table for reference for all the other AT motors out there.

Take your Avg Thrust in lbs and divide that by five - for example let's say you used an I161 with an average thrust of 37.1 lbs of thrust and divided that by 5. You can THEORETICALLY launch a rocket within a range of 7.4 lbs. Even with that very crude calculation I would employ some common sense and run a simulation with Rocksim to see what kind of speed I had off the rail. You'll usually want at least 45 ft/s for a safe flight. The way some of us build around here it doesn't take much to bring the weight up significantly. I think your adapter alone will have the potential to add a pound +/-.

Hey keep up the aggressive attitude, but back it up with lots of questions. You won't get any better "shop talk" than right here!!

Shane
 

marshall1031

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Alright, being that it is winter and I don't have much to do, I'm going to build the Armageddon. After that, or while I'm working on that, I will build a cheap kit just to get my level 1. Now comes the hard part...where do I begin when it comes to fiberglassing? I know nothing about applying it.
 

Zippy

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mshaner,

Do you have that engine data in something other than .xls format? I don't have Excel.

Thanks,
Zippy
 

Ryan S.

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lay a couple layers of Fiberglass on there, Stick an M1315 in there and sit back and enjoy the ride. Dont expect to get it back though:eek:
 

daveyfire

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mshaner

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LONG

1.) Get a gallon of epoxy resin and a quart of hardener. Pick you poison on this one 'cause you'll hear a hundred opinions about West Systems vs. the others. Personally, I dislike the pumps which is typically the selling point for West. I use Everstar epoxy www.evercoat.com. Just make sure you get a 4:1 system.

2.) Purchase yourself a package of bondo squeegees (looks funny is that right?) from you local Autozone. You can go to Wally World, but I prefer the others. Purchase plastic mixing cups, popsicle sticks, lots of papertowels and then go to Hobby Lobby or something like that and get a 1" cheapo white pine, white bristled paint brush or a handfull.

3.) Ready your tubes by sanding them down real well with some 100 grit or so. Then wipe them off and mark a straight line down the tube.

4.)Make up some couplers that will fit in the end of your tubes and wrap a layer of wax paper around them (hold the wax paper in place with clear tape - the kind your wrap gifts with). Then slide these in the end your tubes leaving a couple of inches sticking out. The wax paper needs to be up in the tube as well so you can get the coupler back out.

5.)Then set up your work area with the tube hanging on a rod between two ladders or one clamped to the bench - again, choose your weapon.

6.)I use 6 oz for 6" tubes and up with two layers. For smaller tubes I use 3.75 oz cloth from www.aircraftspruce.com This is a really nice cloth for a smooth finish later. Find a nice clean area, roll your cloth out and measure off a section of cloth that is an inch or two longer than your tube on BOTH ends. Then cut enough off to wrap the tube twice with an 1" or so extra. Carefully fold the cloth and place it next to your working area.

7.) Now comes the fun. Mix up your epoxy in a 4:1 manner (4 parts resin to 1 part hardener). No need to be in a big rush here but work steadily and lay up a couple of cheaper tubes first just for practice and getting a feel for how much you need. Bash an Estes.

8.) Apply liberally to the entire tube a layer of epoxy. It will be a nice glossy look. Now here is where I separate myself from most - I DO NOT slop it on so that it is dripping off the tube. I just gloss it up real nicely so that it will almost run like a crappy paint job.

9.) Take your cloth and line it up with the line on the tube an gently lay it acoss the tube being careful not to pull and tug on it. If you must adjust it, do it with the brush and NOT by lifting an pulling. You'll see why after a tube or two. Take the brush and gently roll the tube while working the cloth down carefully trying to avoid bubbles. If you get one and you will just work it out with the brush. DON'T PANIC and grab it with your hands. As you get toward the ends of the tube let the cloth bond to some expoxy that has been brushed onto the wax paper. It will help keep the ends down. Here's the trick - as you work it outward take your brush and roll your wrist outward toward the end. Basically, you should only use your hands to roll the tube. Be the brush...:D

10.) You will notice the cloth is "wetting out" giving it a transparent look. A lot of people will have quite bit coming through at this point justifying it by saying that it will be soaked up on the subsequent layer. Some is OK, but less is better. Your ultimate goal is to keep the ratio of cloth to epoxy at a 50/50 ratio. Now as you roll the tube around and the second layer is being placed you will use the brush to work it down kind of pulling it around and smoothing as you go. This action forces the expoxy UP and through the next layer without minimal excess.

11.) After you've smoothed it out you may notice a few white looking spots and this is OK. Simply DABB and ROLL a light layer of epoxy on these areas to wet them out.

12.) At this point you may or may not see really shiny areas along parts of the tube. Grab your squeegee (I've got to be spelling that wrong, but for now who cares!), start at your line and pull the squeegee around toward you skimming the excess off into an empty cup after each swipe. The cool part starts here!! Your glassed tube should go to a semi-gloss look and you will be able to see the glass pattern very easily. Keep working this around and around until you've skimmed the entire tube. Use the squeegee to pull in excess to other area if you need to. It almost appears to be drying. This is good.

13.) Now the only thing you'll have to watch is to make sure that the ends don't buckle up a bit in places. You'll have to watch it for 30 minutes or so. No big deal if get a raised spot - very gently use your finger to push it back down. Again, the wax paper and some epoxy on that will mostly eliminate this pain.

OH YEAH - WEAR NYTRILE GLOVES. Latex will do in a pinch, but epoxy will eventually wear it down. I also use a respirator. Anal? Yes.

FINALLLY, after it has cured over night (don't give into the temptation to pull it off the rod early...I know it looks really cool, but don't...you can do this in the morning after a cup of coffee. Take the tube off the rod and pull out the couplers (may be tough, but you can knock them inward a bit and they'll pop loose. Then remove the wax paper if you want. I then take a very sharp hobby knife and run it along the end of the tube cutting off the excess cloth. You should have a crappy looking ring when that is done but a very nice looking tube.

I guess the best thing to remember is to do this when you have plenty of time so you don't rush. It's fun, but it takes practice and patience.

Good Night and Good Luck!


Shane
 

mshaner

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Zippy,

I'll have to scan it in and save it as a JPG. I've tinkered with a bit tonight, but sleep is calling my name. I'll play with it more tomorrow.

Shane
 

daveyfire

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BTW, one of the best investments I made in my composites career was the Shadow Composites curing oven. Layups are now done in 1.5 hrs, not overnight! I can get several things done, even a project finished (with glass) in one day. Heck, it took me only two days to do my Binder Jaguar, aircraft epoxy throughout! :) Highly recommended.
 

marshall1031

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Thanks for that fiberglassing post, I'm going to use it all the way. I think I'm going to buy the vacuum bag kit from West systems for the fins, or is there a better technique to use? My last question is, when I mount the fins, should any other reinforcement at the joints be used, or just the standard epoxy? Oh yeah, would buying a jig be my best bet to mount the fins correctly?
 

Rocketman248

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I would extend the slots all the way to the bottom of the body tube. That way you can tack the fins on with five minute epoxy, then pull the whole motor mount/fin assembly out. Then take strips of fiberglass and lay them over the motor tube/fin joint. I used that technique on my level three project and the fins survived a fall from 6000' on drouge only, as well as a very early ejection.

Pics can be seen here.

Hope that helps:)
 

mshaner

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I have not used vacuum bagging to this point. I know it's a good thing, it looks cool and makes a lot of sense. However, I haven't put the time into it and my method leaves minimal epoxy in place which offsets some of the need for vacuuming in the first place. Ovens are probably a good idea too, but again I haven't put forth the effort as I don't need to finish a rocket in 2 days. It's a hobby and other life issues come into play.

As for the fins structuring. I always glass my fins to the MMT sometimes I even run the glass all the way across the fin. In other instances, I just glass the joint - depends on your flight speed and the rigidity of the fin configuration, swept fins, etc.
Contrary to glassing my tubes I put a very minimal amount of epoxy on my fins as I'm laying them up and wet them out with the brush. I rarely have to skim off any excess epoxy.

As for the jig - I made my own. Here's a nice picture of how I made mine. I've modified it a bit, but you'll get the idea -

http://www.yellowjacketsystems.com/jimball/construction/fin-jig/default.htm

Yes, make yourself a very nice jig, draw lines down you MMT and make sure your angle is a perfect 90 deg off the surface. Doing the setup up front will save you a cussing session or two when you have to rip a kanted fin off to re-glue it.

Rocketman has a good point with his method. Basically the MMT has the fins attached before assembly and is slid into the BT with the slots pre-cut. Here is a link to such a process:

http://photos.yahoo.com/bc/mshaner_climb/lst?.dir=/Cluster+Struck&.src=ph&.view=

You're on the right track.

Shane
 

marshall1031

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Can anyone recommend a type of epoxy to use for the joints? I've heard that JB Weld is a good choice. Thanks.
 

mshaner

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I use the same epoxy that I use for glassing only in smaller portions and thickened with micro-balloons. You can also cheat with some baking soda.

Some also use 5 min....

Shane
 

havoc821

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marshall,

Welcome to the forum! I am doing the same thing as you. Getting a big rocket, 75mm MMT so you can always size down and going BIG!! I am not even old enough to get certified but you can read my story a few threads below to "my first high power rocket. Good luck with your rocket! BTW JB Weld is great! I am afraid to go back to using epoxy except for fin fillets. It is so much stronger than epoxy. I took some extra epoxy and extra JB Weld that I didn't use and layed it down on my garage floor, took a hammer and hit each 5 times with the same strength and the epoxy shattered on the 2nd swing and the JB Weld only suffered a few small crachs and it got a little flattened. Anyways, hopw this helps and good luck!:D
 

marshall1031

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That sounds like a pretty good test. I think I'll go with the JB weld. Thanks. :D
 

havoc821

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No problem. Can't wait to hear more about your rocket and I'll try to keep updated with mine. I have pictures but they are too big. :(
 

daveyfire

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Originally posted by havoc821
BTW JB Weld is great! I am afraid to go back to using epoxy except for fin fillets. It is so much stronger than epoxy. I took some extra epoxy and extra JB Weld that I didn't use and layed it down on my garage floor, took a hammer and hit each 5 times with the same strength and the epoxy shattered on the 2nd swing and the JB Weld only suffered a few small crachs and it got a little flattened.
Ummm... JB Weld IS epoxy, with some fillers and additives to improve its temperature and strucutral properties. Epoxy without anything in it is relatively weak, and is very brittle by nature. That's why the epoxy shattered, but the JB Weld didn't. That's also why JB Weld is so much thicker -- it's got filler in the hardener (also makes it a 1:1 mix ratio vs the 4:1 or 5:1 of unthickened epoxies). You can get similar physical properties from epoxy by simply adding a filler such as Cab-O-Sil, West 404/406, Microballoons, or as mshaner suggested, even baking soda will work. This will significantly improve the strength of epoxies. JB is great for tacking fins in place, though I don't like it for high volume applications (e.g. fillets) because of its high cost. A gallon of Aeropoxy and hardener is $50. 10 tubes of JB Weld is $50. I like saving money ;)

I've had rockets fall on drogue only from 10K with epoxy/filler fillets onto a packed dry lakebed with no cracks or problems. I have also seen rockets with just epoxy/filler fillets and a little glass on minimum diameter rockets go past Mach 2 with no problems. Now my rockets, on the other hand, seem to have stability issues around there, so I couldn't tell ya :D

My 2 cents :)
 

daveyfire

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Fillets are radiused epoxy joints that go between the fin and the tube you're gluing the fin to. They lower drag (less surface area) and make the joint much stronger. Also, when laying composites, fillets help the fabric to blend from surface to surface. By avoiding sharp corners, the fabric is more likely to lay down flat without bubbles.

They also make the rocket pretty :D

Do a search for "fillet" in the forum and you'll get a lot of info!
 
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