Rocket building tips

Hello everyone!
I am getting back into model rocketry after a few years absence. I had participated in rocketry every year in 4-H and had a great deal of fun
doing it. Now, as I reaquint myself with the hobby and looking at my expirences as a kid, I see there were a few things I have to improve on and a few questions to go with. So, please forgive me if I'm asking you to go over topics already discussed. Thanks.
For now I'm interested in building rockets on the level of those offered by Estes and Quest.
1. What sort of glue do you recommend for various components beyond white Elmer's glue and how do you recommend applying them to specific joints?
2. What's a good method of getting a good, clean leading edge on fins?
3. Another fin question, how do you get your's smooth? What do you apply to your fins and how many times do you repeat the sand-apply cycle? I know, a pretty basic question, but this one always drove me nuts as a kid.
4. How do you rid your rockets of that spiraled trench on the body tube? Use the same stuff as the fins and sandpaper I suppose?
5. Could someone tell me about these Kevlar shock cords I have read about and the various methods to use them?
6. Please recommend a good rocket building book with tips like these.
Thanks for taking your time to answer my questions. I can't wait to get some of the kits I bought today built and off the ground. I'm planning on going to Tripoli Southern Minnesota's launch on July 25th so perhaps I'll see some of you there!
Daniel Bergquist Rev. 2:10
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snipped-for-privacy@cune.org wrote:

For Estes/Quest models (referred to by many as Questes rockets <G>), use the yellow "'carpenter's glue" rather than plain white glue. Strongest joint is made by applying glue, pressing the surfaces together, remove them, wait one minute or so until it becomes slightly 'tacky', put the surfaces back together, then wait until they dry and apply glue fillets (note this is for fins, not for putting an engine block in a tube -- for that, put it in quickly, and cleanly).

Sandpaper. I use 400 or 600 grit, as needed depending on the fin material/thickness.

I use either balsa fillercoat or sanding sealer, available at any good hobby shop. You'll need 2-3 coats. Apply, wait until it dries thoroughly, sand, then repeat until satisfied. Don't breath the crap you're sanding, use ventilation and/or a face mask.

Yes, or thinned Elmer's Fill'N'Finish.

Quest tends to use the Kevlar shock cords. I am tending to put a Kevlar cord attached to the body tube these days, but still attach elastic from the end of the Kevlar to the nose cone. Or, use a longer piece of Kevlar.

There's probably more you'll find on the internet than in books. Look here:
http://www.info-central.org/infocentral.shtml
David Erbas-White

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On Thu, 23 Jun 2005 22:55:41 -0700, David Erbas-White

What David said except & use 220 grit paper and don' fill spirals. The spirals are a 'design feature.'
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David Erbas-White wrote:

That sounded almost apologetic. Don't be, those kits are still a boatload of fun for me and I'm planning toward my level 2 and all the extra psycho things that can let me do.

Although it's overkill for model rockets, epoxy. However if you're planning on eventually going to bigger and better things you'll need to start using the stuff. Here at the start 5-minute epoxy is perfect. It sets fast and the redundant strength will allow for leeway if you get the mix not quite right. And better to have the learning curve eat a small kit, rather than a larger more expensive one down the line. Word of caution, wear gloves when working with the stuff, don't get it on your skin if it can be avoided as it can be a nasty irritant.

And of course a sanding block. That should be obvious but since this is entry level 101 type questions I wanted to make sure that wasn't forgotten.

On some of my larger rockets, where weight is less a concern, I've also used finishing epoxy and wet sanding for both the above. One slight disadvantage is that it seems to foul up the paint's adhesion. Least that happened with my one rocket, the paint cracked and peeled off the nosecone while in flight.

Kevlar always seemed a bit redundant in model rockets to me, but the heat resistance _does_ solve the rather annoying problem of 'chute separation. I agree that adding some elastic for extra shock absorbtion is a good thing. In kits that come with elastic cords the advice I got at my return was to pitch the stock cord and replace it with one that's 2-3 times longer. In general there's no such things as too much shock cord, if there's still room in the rocket yours is too short.

That's what we're here for. To talk incessantly about our hobby and give helpful hints in the process :-)
Chuck
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That wasn't ment to sound apologetic. More of the indication of types of rockets I will be working with and an indicator for the types of answers I'm looking for. Just about my favorite rocket that I have built was an Estes Mean Machine. On the third launch the nose cone didn't eject, probably since I prepped the rocket far too long in advance, and the thing did a nice rainbow before it made it's mark on the Earth. :-( Heh, since I was probably in jr. high or so and when I realised what happened I started spouting tears as the thing came down. I guess I'll have to hit eBay or something of the like to find a new one since it seems Estes doesn't currently offer the kit.
Daniel Bergquist Rev. 2:10
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snipped-for-privacy@cune.org wrote:

Daniel,
Do a google on the Mean Machine as I bought a second one a month ago from either hobbylinc or commonwealth hobbies. Red Arrow hobbies would be another online place to try.
Kurt Savegnago
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On Fri, 24 Jun 2005 10:40:28 -0400, Zathras of the Great Machine

Yeah, that was the suggestion given to me by Steve at Commonwealth. I've started replacing the one that comes in the kits with longer cord. On all the RTF birds I get, I immediately cut the supplied shock cord and install a longer one. Since I've been doing that, I don't think I've had one separate yet(70+ launches). I can see some damage on the cord for my Big Daddy. So I need to replace it, but at least it didn't break in flight.
Eldred
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My personal rule of thumb for all rockets is to make the recovery harness (shock cord) at least 4x the overall length of the rocket. Longer is better. Allows air pressure to slow the ejected parts a bit some before they come up short at the end of the harness. I've tested to lengths of 7x the rocket length without problems.
Kevin O
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A rule of thumb that doesn't always make sense. Compare the shock cord needs of a Fat Boy and a Mean Machine...
    Bob Kaplow    NAR # 18L    TRA # "Impeach the TRA BoD"         >>> To reply, remove the TRABoD! <<< Kaplow Klips & Baffle:    http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org
This is a country which stands tallest in troubled times, a country that clings to fundamental principles, cherishes its constitutional heritage, and rejects simple solutions that compromise the values that lie at the roots of our democratic system. -- Supreme Court Justice Thurgood Marshall, 1972
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On 24-Jun-2005, kaplow snipped-for-privacy@encompasserve.org.TRABoD (Bob Kaplow) wrote:

Indeed. Durn those extremes. Especially with me all thumbs.
KO

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On Fri, 24 Jun 2005 17:57:43 GMT, "Kevin OClassen"

I normally do 3x to 3.5x the length, maybe more for heavier nosecones. 7x? Phew... :-)
Eldred
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Daniel,
Welcome back to the hobby. Much has changed, as you are sure to discover. Since you mention your interest is in Quest/Estes size/skill rockets, I would like to invite you to visit FlisKits at http://fliskits.com/ We are a 3 year old company with a lot to offer.
To see what our customers say, you can read their reviews of our products on a site called EMRR (Essence's Model Rocketry Reviews) at: http://www.rocketreviews.com/cgi-bin/search/searchall.cgi?fliskits
To answer your questions, see below:
snipped-for-privacy@cune.org wrote:

Yellow glue is great stuff. Much stronger bond. For quick tacking of the fin in place, I would recommend a super glue (Cyanoacrylate or CA glue). This can also be used with an "Accelerator" to really speed things up. You would still want to use the yellow glue for fillets (a film of glue spread into the joint between the fin and the tube, for strength). Use yellow or (more recommended) white glue for installing the engine block or engine mount.

Take your time. What I do is lay (or glue) a sheet of sand paper to the edge of a flat surface. I then hold my fin with my fingers putting pressure on once side as I press the leading edge onto the sand paper with steady back and forth motion across the sandpaper. I stop often to check progress and progress to finer and finer papers as I get close to the shape I want. A curved leading edge is (for me) the easiest to do and helps in painting (paint doesn't like a hard corner or edge)

I have been a fan of Sanding Sealer (4-5 coats sanding between each coat) for years. Lately I have switched to using Elmers Fill-n-Finish. You can thin it with water or apply it right from the can. It is inexpensive, oderless and water cleanup. It dries well and is easily sandable. Takes practise but works very well. You can find this in any home improvement store.

Yep, same stuff for the spiral. I can't speak for other companies, but FlisKits tubes have been praised for a very small spiral.

Kevlar is great stuff. Very strong for its size, flame/heat resistant and fairly easy to get (these days). The biggest problems with Kevlar are 1) it doesn't stretch and, 2) You may be prone to "zipper" your body if the nose cone deploys at too great a speed (zipper: The kevlar will slice down the length of the body tube as the cone pulls back in a high speed ejection) As others have mentioned, I use a mix of kevlar and elastic so that there is *some* shock absorbancy in the system.

G. H. Stine's Handbook of Model Rocketry. This will become your favorite resouce :)

You are most welcome!
jim
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discover.
Ha ha, well, I don't think it's chaged that much for me. I guess I forgot to mention my involvement in this hobby waned in high school. I'll currently 22. :-)
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snipped-for-privacy@cune.org writes:

I like a thick cyanoacrylate (superglue). Permatex makes one that I use for almost everything.

A sanding block.

Elmer's makes a lightweight water-based wood putty whose name is escaping me at the moment (Fill 'n' Finish, maybe?).

Yep.
I can't give a better recommendation than to just look at how Quest does it (for small rockets).
--
Joseph J. Pfeiffer, Jr., Ph.D. Phone -- (505) 646-1605
Department of Computer Science FAX -- (505) 646-1002
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writes:

Almost all sanding should be done with a sanding block, be it model rocket, carpentry, or whatever.

One of the few exceptions to the rule above. Wrap the sandpaper around the tube and stroke rapidly :-)
    Bob Kaplow    NAR # 18L    TRA # "Impeach the TRA BoD"         >>> To reply, remove the TRABoD! <<< Kaplow Klips & Baffle:    http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org
This is a country which stands tallest in troubled times, a country that clings to fundamental principles, cherishes its constitutional heritage, and rejects simple solutions that compromise the values that lie at the roots of our democratic system. -- Supreme Court Justice Thurgood Marshall, 1972
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Would you recommend using the glues previously mentioned when mounting fins onto plastic tail pieces such as those found on Estes Canadian Arrow?
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snipped-for-privacy@cune.org writes:

(please include enough context so we can be sure what you're responding to!)
CA -- yes. white or yellow glue won't hold to plastic at all.
--
Joseph J. Pfeiffer, Jr., Ph.D. Phone -- (505) 646-1605
Department of Computer Science FAX -- (505) 646-1002
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snipped-for-privacy@cune.org wrote:

You can try plastic cement but I am taking a liking to a Devcon plastic epoxy. It is two part and cures pretty quickly.
On painting, a fellow posted here awhile back that after priming and sanding a model one should shoot a final light coat of primer and NOT sand it for better adhesion. It will feel kind of grainy and after I've done three models that way, he is right. Have had no problem with paint adhesion. Will also "sand" a body tube with 220 grit to roughen the tube up for better primer adhesion. I of course use the fill 'n finish to fill the spirals if I want the seamless look.
I wish I could give you a pointer to the thread but the subject did not give any direct idea as to what was in the body of the message and I lost it.
Kurt Savegnago
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snipped-for-privacy@cune.org wrote:

many of the new Estes kits seem to be made of plastic that is not reliably glued by the usual Testors tube cement. instead use some liquid plastic cement. It's nasty stuff, has MEK in it, but works well.
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Cliff Sojourner wrote:

The "usual Testors tube cement"...is in no way "usual". The one group of people who probably avoid it more than any other group...is serious plastic modelers...lol. Most serious plastic scale modelers find it useless.
Testors LIQUID Cement is about the best thing ever invented. Bonds/welds excellently, with plenty of working time....and with none of the harsh nastiness of MEK-ish substances.
--

Greg Heilers
Registered Linux user #328317 - Slackware 10.1 (2.6.10)
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