Wood Glue strength for L2 flight?

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AfterBurners

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I was always told or should I say that I learn this on here that using wood on materials of card board and wood that the joint adhesion itself is stronger than the actual materials being used. So it makes when joining wood and card board to use wood glue.

Then why is it so many of us use epoxy or some form of it to join these like materials? Epoxy is best suited when using unlike materials such as wood and plastic, plastic and fiberglass, carbon fiber, fiber glass etc.

I'll be starting my L2 project soon and I plan on purchasing the MADCOW Patriot 4" kit and using wood glue throughout the build. The only time I plan on using epoxy is to join the motor mount to the airframe and also the tube coupler because I know how easily wood glue likes to "lock up" when gluing these types of parts.. This rocket in turn will be a lot lighter and performance will be increased because of it's lighter weight. Also I won't have to spend a lot of time shaping fillets. Of course I will upgrade the recovery harness and I plan on using a 3rd ring to lock in the fin tabs.

I'm keeping it simple using engine deploy and will be flying it on a 38mm J500 for the cert flight. My reasoning as most have mentioned here is stick with something you know and get the certification. I figure once I get certified for L2 then I will focus on becoming proficient with DD, air starts, staging and clustering, electronics and wiring. It just makes sense to me to do it this way, because taking the time to learn these aspects of the hobby will better prepare myself for my L3 when I'm ready to achieve it. Who knows when that may be? I want to set goals and each project / build do something unique and different that I never tried before and whether I succeed or fail take something from it.

I love this hobby so much and not sure why myself and everyone can be so consumed by it? There's so many aspects about this hobby to enjoy and I just can't pick one I can pick a few and this is why I (we) love it so much.

I want to thank you guys for all your insight and advice. You made be a better builder, painter and an addict to this hobby :)

I hope everyone has a great week!!
 
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Dan-Rock(et) On! I recently built a Minnie-Magg with only wood glue to keep it light. Due to rocket fever I also cratered the same at a little over 500 mph. It hit so hard I broke the CF filament wound DMS motor case! I got a little wiggle at the transonic approach and I was waiting for the shred. Didn't happen. Thought I could salvage the fins-also didn't happen. Those suckers are on for good! Sounds like you have a good plan and can't wait to see you fly it. Enjoy the build!
 
Not at all, as long as you are using wood and paper/cardboard the wood glue is definitely as strong as the epoxy, in other words the fact that the epoxy is stronger than the wood glue wont matter, since both are stronger than the base materials. Titebond II is my preferred wood glue as it is stronger than Titebond, and slightly stronger than TBIII. I prefer TBII because I have worked with it for years doing wood working and have even tried the glue joint failure test on several woods and every time the wood failed not the glue. Somebody around here even built a L3 rocket with wood glue iirc. The only place I might consider epoxy is the external fin fillets, just for the single pass fillet, not building it up like wood glue or TMTG (Titebond Molding and Trim Glue).
 
I have heard of rocketeers using wood glue on L3 rockets with great success. Believe Ari (iter) used wood glue on his 3" Blue Fin Tuba and it went up on an M. First tube fin rocket I'm aware of that went mach without failure.
 
I use II and III as the situation demands. Both have their strengths...
 
I think you'll be fine. I used a J500G for my L2 as well. Sweet motor :)
 
one problem with wood glue is that, it doesn't fill gaps in the joints worth a darn. that said, you shouldn't have that problem w/ the Mad cow kit. I would suggest applying ca (and sand smooth)to the payload bay coupler(after it is epoxied in place), this will make life easier. nice kit, did my L1 with one.
Rex
 
one problem with wood glue is that, it doesn't fill gaps in the joints worth a darn. that said, you shouldn't have that problem w/ the Mad cow kit. I would suggest applying ca (and sand smooth)to the payload bay coupler(after it is epoxied in place), this will make life easier. nice kit, did my L1 with one.
Rex

For the coupler and motor mount assembly I'm going to use 30 minute epoxy to build and install them. but for the fins and fillets I'm going to use Titebond II and as you mentioned about the gaps that the wood glue leaves I'm going to go back over them with Titebond Molding and Trim. At least I think that's what they still call it, but you know what I'm talking about. I mean I have no issues with epoxy, but using wood glue you really don't have to wait long to complete the process and it cleans up so much easier and you don't have to spend a lot of time shaping and sanding. We've all done that before, but sometimes I just don't feel like doing it. Even when using wood glue for fillets I still mask them off with blue tape to keep them uniform.
 
I used Titebond II and the Molding and Trim glue to build my Warlock. I used JB weld for the motor retainer and the rail guides, but the rest was wood glue. I haven't flown it yet, so let's hope it holds together!

For this rocket, the thrust loads do not seem to be born by the adhesives very much. The thrust ring pushes on the motor retainer, which is seated right against the aft CR. The CR is in direct contact with the fin tabs. The fin tabs are in contact with the forward ends of the slots. It seems to me that the thrust is being transferred to the airframe through the interlocking structural components, not the glue joints between the motor tube and CR, or CR and BT.

I prefer working with wood glue mostly because I'm not great with handling epoxy. I seem to get it on stuff where it does not belong.
 
I used Titebond II and the Molding and Trim glue to build my Warlock. I used JB weld for the motor retainer and the rail guides, but the rest was wood glue. I haven't flown it yet, so let's hope it holds together!

For this rocket, the thrust loads do not seem to be born by the adhesives very much. The thrust ring pushes on the motor retainer, which is seated right against the aft CR. The CR is in direct contact with the fin tabs. The fin tabs are in contact with the forward ends of the slots. It seems to me that the thrust is being transferred to the airframe through the interlocking structural components, not the glue joints between the motor tube and CR, or CR and BT.

I prefer working with wood glue mostly because I'm not great with handling epoxy. I seem to get it on stuff where it does not belong.

Like I said I could go either way with it, but I would like to just build a rocket using wood glue and keeping it reasonably light. I believe epoxy serves a purpose and has application for like fiber glass and other different materials. I try to build my rockets according to usage and not like a tank. The lighter it is the higher it will go and its safer.
 
Like I said I could go either way with it, but I would like to just build a rocket using wood glue and keeping it reasonably light. I believe epoxy serves a purpose and has application for like fiber glass and other different materials. I try to build my rockets according to usage and not like a tank. The lighter it is the higher it will go and its safer.

Totally agree. I think you could easily build it with wood glue, keep it nice and light, and have no problems at all with the strength of the rocket.
 
Either glue will work fine. I normally use epoxy on HP rockets the reason "it's what I like using". On larger rockets it is easier to make fillets at joint using filler and epoxy. If you are doing any type of reinforcing with FG or CF than of course epoxy is the only way to go. I have used wood glue and have never had an issue gluing wood to wood, paper to paper or wood to paper. A well cut clean joint is the only requirement. I have used various versions of Titebond depending what was available on my shelf.
 
So far the best built model in my fleet was build with wood glue for everything but the tiny little fillets. I only used epoxy there because I knew what I was going to be getting since it's non-shrink. It's also extremely light which is nice because it opens up a world of motor possibilities. Wood glue it so underrated in out hobby.
 
I used wood glue almost exclusively on my L2 rocket. I did use some polyurethane glue for the motor mount and gluing the stiffy in the coupler for the av bay. Internal fillets were done using wood glue and square dowels, with the standard epoxy and micro balloons for the external fillets. Frankly, I could have just done my normal wood filler and CA for the external fillets. The fins were plenty strong structurally with the dowel reinforcements.

No problems with the L2 flight. Afterwards, Go Fever lead to a less than optimal flight. The fin can survived the lawn dart. The rocket has been rebuilt and is just waiting on decent weather to finish the paint job.
 
I have a 4" x 54 MM built with epoxy and a 3" x 38 MM built with Titebond 3 & Trim with the exception of the CA used to retain the T-nuts for the motor retainer. I will use one or the other for my Level 2 cert depending on the field, weather conditions, motor availability and finances.
 
Internal fillets were done using wood glue and square dowels

Do you by any chance have pictures of this? Curious how the dowels help, does it just result in a wider fillet? I guess the wood is lighter than the wood glue would be?

I guess a general question about using wood glue for something like internal fillets. I'm used to using wood glue in places where there's a tight fit and/or pressure, which seems to help the glue cure. But do you really just pour glue in the valley between the fin root and MMT and just wait for it to dry, or is there some other technique to use here (like the dowel suggestion, but do you then clamp the dowel to either the fin root or the MMT)?

I'm re-building my Excel w/DD and am using more wood glue this time around, but I'm at the internal fillets and trying to decide how to proceed from here.
 
I'll see if I have any pictures at home.

Adding the dowel gives a much larger surface area for the loads. I didn't clamp the dowels down, just relied on the grab when I pressed them in. I did use a long screwdriver to press along the length. This was a 4" tube with 54mm motor. On the 1/4" fins (over sized, but it was an upscale), I think I used 1/8"x1/8" basswood dowels.
 
I'll see if I have any pictures at home.

Adding the dowel gives a much larger surface area for the loads. I didn't clamp the dowels down, just relied on the grab when I pressed them in. I did use a long screwdriver to press along the length. This was a 4" tube with 54mm motor. On the 1/4" fins (over sized, but it was an upscale), I think I used 1/8"x1/8" basswood dowels.

So you used a standard woodworking technique to reinforce the joint between the MMT and the Fin by glueing a dowel down the length of the fin root, in woodworking we typically reinforce joints with a triangular blocks glue into 90 degree corners.
 
yep. On my Lil Nke (surface mount fins) I sanded the square dowels into triangles since they're external fillets and used glue rivets. That I can definitely get a picture of since I haven't painted it yet.

On the L2 4" rocket, I did this on the fin/MMT joint and the internal fin/BT joint.
 
From someone who has built A LOT of wood glue only rockets you'll be fine. I would even trust it to go past mach so long as you use good build techniques such as good fin alignment, sanding surfaces that are being bonded and so on. About the only thing I use epoxy for is to bond dissimilar and non wood materials or to coat bulkheads that have ejection charges blowing up nearby. The phenolic tubing I get from Red Arrow Hobbies seems to really like Titebond II.

As others have said a lot of people have done L3 projects with wood glue with great success and someday when I do my L3 that's the route I plan on going.
 
Turns out I don't have any pictures of my internal fillet dowel reinforcement L2. I'll do one this weekend on a 3" w/38mm MMT and get pics. The Lil Nuke has too much wood filler now to show the reinforcements.

Here's some pictures. I smeared the fillet joint with glue prior to starting to do a semi double glue joint.
Tools - long screwdriver and popsicle sticks
Tools.jpg

Glued dowel
Glued dowel.jpg

Press into place (the glue on the popsicle sticks help hold the dowel until you press it into the joint)
Place.jpg

Press firmly with screwdriver to seat
Press.jpg

Done
Done.jpg

Since these are for the upper set of a split fin rocket, they're not the best. If you want, I can get picks of the lower set too.
 
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