Building paper and wood MPR without epoxy (mostly)

[neil_w]

I'm thinking about building an MPR this year, would be my first. Haven't decided if I want to go with one of the discounted PSII kits (because they're cheap) or get what I really want, which is one of the NCR kits (Lance Delta or SA14 Archer). We'll see.

Either of these would be pretty much all wood and paper (other than the NC, which isn't glued anyway). And therefore I wonder whether it would be reasonable to build primarily with wood glues. I might have reasons (never mind what they are) to minimize my use of epoxy, though I'm OK with small applications here and there.

I know John Boren has said (if I remember correctly) that he builds his PSII models without epoxy, and Matt Steele at NCR told me that although he prefers epoxy, his models should work fine with wood glue as well. So it certainly seems possible, but I'm trying to figure out what pitfalls to look out for.

Given that that wood glue bonds (Titebond II is my go-to) are allegedly stronger than the wood and paper themselves, where in such a build would forgoing epoxy put me at a disadvantage? There are three possible areas I can think of:

1) Gluing motor mount into airframe: same consideration as with LPR, epoxy won't seize=
2) Any attachments to the motor mount where high heat tolerance is needed. I'm not really sure how much of an issue this is, or if something like Titebond II would be insufficient in any way.
3) Exterior fillets. I love my Titebond No Run No Drip, but I've never tried to use it to create the sort of monstrous fillets that are typically employed on larger rockets. Is it even practical to do so? Would I use the same technique as for epoxy fillets (mask, pour, draw, unmask)? Or would I just have to live with smaller fillets, at the cost of aerodynamics/strength/appearance?

I'm not committed to this idea yet, just feeling things out. Input appreciated.

 

[samb]

My LOC Doorknob was built with Titebond II, Gorilla polyurethane for the motor mount, and JB Weld for the retainer. I've reached the point in life that some here have mentioned where epoxy gives me the heeby jeebies. Not a full blown allergic reaction but definitely something. This rocket flew on a J460T for my level 2 cert. I think glue is a personal choice, depending on materials being glued




courtesy of Chris Bender:
https://darsrocketrypics.shutterfly.com/pictures/2018#2006

 

[dixontj93060]

You can build HPR with wood glue like my Binder Stealth and fly K's and L's so you should be fine with any MPR build. One thing I found I don't like to do is fillets with any form of wood glue as the shrinkage requires multiple applications even if you use a "special" wood glue like Titebond Molding and Trim.

 

[neil_w]

Great thread, I am encouraged (and I frickin' love the black-on-black lettering).

I would certainly expect to need at least two applications of TM&T (really TNRND these days), but even then not 100% sure how big a fillet I can achieve with it. Did you try masking the fillets, or just went freehand?

 

[Rex R]

main consideration for using white/yellow glue is; are the joints tight? neither of those glues does well at filling gaps. heat shouldn't be an issue. save the epoxy for the motor retainer and couplers.
Rex

 

[ThirstyBarbarian]

The Titebond glues will work great for any wood and paper rockets. Like samb above, I built my Warlock rocket using wood glue. That rocket has flown on an I540, and I plan to use it for my L2 later this year.

I always use wood glue when I can. The only exceptions are places like you mentioned where the bond might grab (couplers mostly) and bonding dissimilar materials. I use the Gorilla polyurethane on couplers because it does not grab. Just remember, it expands a bit, so use less than you think you need. I haven't had motor mounts grab, so I still use wood glue for that. I use JB Weld to glue on metal or plastic motor retainers and conformal rail guides.

I don't really do much with large fillets anymore. The no run no drip glue works, but it takes a few applications. On LPR rockets, I've used wood filler for cosmetic fillets.

Good luck with MPR! You can't beat the price on the Estes PSII kits right now, so if money is a concern, that's the clear winner. But if you can afford to get what you really want, do that, especially if you like to do a lot of finishing work and painting.

 

[neil_w]

main consideration for using white/yellow glue is; are the joints tight?

Yes, I'm trying to focus a bit more on that after being a wee bit careless in my first few builds.

I haven't had motor mounts grab, so I still use wood glue for that.

I'm starting to think that the motor mount grabbing problem is mostly when using the thick cardboard rings such as these. They have a lot of surface area and they do grab hard (encountered this in a small but non-fatal way on my Cyclone build). I guess those rings sort of behave like couplers in that respect. When working with flat cardboard or plywood rings I haven't had a problem (yet).

Good luck with MPR! You can't beat the price on the Estes PSII kits right now, so if money is a concern, that's the clear winner. But if you can afford to get what you really want, do that, especially if you like to do a lot of finishing work and painting.

Actually, one thing I like about those particular NCR kits (other than the design) is the fact that they're all white paint. One painting session and finished (other than priming)! Me likey. Don't mind doing the decals/stickers/whatever, that's fun.

Thanks for all the replies, I feel very good about this now.

 

[Banzai88]

Just a note on parts fit Estes PSII vs. NCR if you're into that sort of thing.

I've built from both vendors since last spring. I started with a Leviathan. Parts fit, as with most every Estes PSII kit, is amazingly good, with very little sand to fit.

Then I fell in love with the NCR Archer. I like the design, but coming from the Estes kits, parts fit would charitably be called "Loose" and uncharitably called "Hand full of BBs in a box car at high speed loose". Consequently, wood glue with the Estes was fine, but for gap filling, I decided that with the NCR kit epoxy was the only way to go.

YMMV.

 

[watermelonman]

I used wood glue exclusively on my Leviathan, except for JB Weld on the retainer, and it can handle an H no problem.

 

[neil_w]

Then I fell in love with the NCR Archer. I like the design, but coming from the Estes kits, parts fit would charitably be called "Loose" and uncharitably called "Hand full of BBs in a box car at high speed loose". Consequently, wood glue with the Estes was fine, but for gap filling, I decided that with the NCR kit epoxy was the only way to go.

Good to know, thanks.

 

[dixontj93060]

Great thread, I am encouraged (and I frickin' love the black-on-black lettering).

I would certainly expect to need at least two applications of TM&T (really TNRND these days), but even then not 100% sure how big a fillet I can achieve with it. Did you try masking the fillets, or just went freehand?

I believe I masked them, but can't remember exactly--I tend to be semi-random on that type of thing.

Yes, I loved the black-on-black Stealth. It was recently sold to a fellow TRF member.

 

[jd2cylman]

I built my NCR Big Brute with all wood glue (TB II). I used Titebond Molding and Trim for the fillets. One pass only for the fillets (one huge fillet pass). Shrank (is that a word??) a little, but the key is a huge fillet to start. I think they took two days to dry completely.
View attachment 279918
I don't know if you can zoom up enough to tell, but I think they turned out OK.
Flying weight W/O motors or cases is 2lbs 5 oz.

Adrian

 

[dixontj93060]

I built my NCR Big Brute with all wood glue (TB II). I used Titebond Molding and Trim for the fillets. One pass only for the fillets. Didn't shrink at all.
View attachment 279918
I don't know if you can zoom up enough to tell, but I think they turned out OK.
Flying weight W/O motors or cases is 2lbs 5 oz.

Adrian

Hey! There are some built rockets in that workshop?!??! I thought there would just be a big pile-o-parts?!

Poor Pershing II . Probably won't get built until 2025...

 

[jd2cylman]

Hey! There are some built rockets in that workshop?!??! I thought there would just be a big pile-o-parts?!

Poor Pershing II . Probably won't get built until 2025...

The longer I wait, the more collectible it gets, right?
Did you see the PML 1/2 Patriot cone and upper body tube in the back left? Yeah, that'll take a little longer to get done (started )
Hmm, maybe a Titebond II PML Patriot? I bought it from an old rocketry auction site in the early 2000's (don't remember who or where). It never came with the 54mm motor mount tube, so I figured that was a good excuse to build it with a 98mm hole

Adrian

 

[dixontj93060]

The longer I wait, the more collectible it gets, right?
Did you see the PML 1/2 Patriot cone and upper body tube in the back left? Yeah, that'll take a little longer to get done (started )
Hmm, maybe a Titebond II PML Patriot? I bought it from an old rocketry auction site in the early 2000's (don't remember who or where). It never came with the 54mm motor mount tube, so I figured that was a good excuse to build it with a 98mm hole

Adrian

Phenolic tubing + 98mm = Epoxy

 

[kcobbva]

My LOC Doorknob was built with Titebond II, Gorilla polyurethane for the motor mount, and JB Weld for the retainer. I've reached the point in life that some here have mentioned where epoxy gives me the heeby jeebies. Not a full blown allergic reaction but definitely something. This rocket flew on a J460T for my level 2 cert. I think glue is a personal choice, depending on materials being glued

View attachment 279821

courtesy of Chris Bender:
https://darsrocketrypics.shutterfly.com/pictures/2018#2006

Oh darn. Haven't seen that one before. Sweet! May have to consider that as a future build. Guilty of "big envy" here.

 

[jd2cylman]

Phenolic tubing + 98mm = Epoxy

Yeah, I know... It will also need to be glassed. Which is another reason why it hasn't been started yet :blush:
Plus, I think it'll need thicker fins than originally supplied. The FG fins are only .093" thick. Can you say flutter...

Adrian

 

[Tonimus]

My Estes Ventris is built with all wood glue except for the motor retainer. Even has the Estes teabag shock cord anchor. I've beaten the hell out of it and the glue joints are SOLID. The tubes on the other hand, are starting to show wear from the aerotech ejection charges.

 

[watermelonman]

My Estes Ventris is built with all wood glue except for the motor retainer. Even has the Estes teabag shock cord anchor. I've beaten the hell out of it and the glue joints are SOLID. The tubes on the other hand, are starting to show wear from the aerotech ejection charges.

Hah yes, my Leviathan was originally dual deploy and then I figured out that two charges per flight was going to lead to a short lifespan.

 

[samb]

Oh darn. Haven't seen that one before. Sweet! May have to consider that as a future build. Guilty of "big envy" here.

[I'll risk a little more topic creep here since I think the responses have convinced neil_w that wood glue is not a limiting factor as you move up the impulse ladder.]

LOC Precision (https://shop.locprecision.com/main.sc) is one of the older high power vendors around. The Doorknob satisfied my desire for a big "model" (wood/paper/plastic) rocket that I could fly without electronics initially. This forum has a few threads on it and its little brother, the Warlock. They are available from many of our fine vendors; Mr. Bob at Countyline (https://www.countylinehobbies.com/) hooked me up.

 

[neil_w]

[I'll risk a little more topic creep here since I think the responses have convinced neil_w that wood glue is not a limiting factor as you move up the impulse ladder.]

Creep away, as you say the original question is well-answered. In advance of actually starting on one of these kits, I think I'm actually going to make myself a little fillet test-fixture (a balsa wood "X"), and practice making large fillets with Titebond NRND, so I should have a clue what I'm doing before I mess up a nice kit. I'll post back here if I get any interesting results.

LOC Precision (https://shop.locprecision.com/main.sc) is one of the older high power vendors around. The Doorknob satisfied my desire for a big "model" (wood/paper/plastic) rocket that I could fly without electronics initially.

That kit is a huge win just for the name. How much does it weigh without engine, and what do you fly it on?

 

[samb]

...


That kit is a huge win just for the name. How much does it weigh without engine, and what do you fly it on?

I think they borrowed the name from Sandia Labs : https://www.astronautix.com/fam/doorknob.htm

It goes about 10.sumpin pounds. 54mm J's and K's and I got a 38mm adapter but I haven't flown it yet. I didn't have an alt for the cert flight on the J460T but it stayed in sight the whole way and recovered about a half mile or so downrange. Fits my flying style as I'm not an altitude junkie.

 

[MikeyDSlagle]

I have had issues with wood glue "shrinking" the body tube where the centering rings were glued, leaving visible depressions on the finished rocket. I think it only happened on my Partizon and maybe my Big Daddy. Maybe it only occurs on larger diameters.

Mike

 

[neil_w]

That is a legitimate argument in favor of epoxy for motor mount installation. I haven't encountered this phenomenon, though, so I don't have a feel for how bad it looks.

 

[dixontj93060]

I have had issues with wood glue "shrinking" the body tube where the centering rings were glued, leaving visible depressions on the finished rocket. I think it only happened on my Partizon and maybe my Big Daddy. Maybe it only occurs on larger diameters.

Mike

That will only happen with thin wall Estes-type tubes. It won't happen with thicker tubes for HPR builds like those from LOC or Binder.

 

[ep29030]

It is true--aliphatic glues (wood glue like Titebond) shrink as they cure, and draw glued parts together as they shrink. I have rockets with a ring where the centering ring was glued to the airframe. For that reason, I would not recommend Titebond for centering rings. On the other side, that is EXACTLY what you want the fins to do--get pulled tighter to the airframe. So Titebond is perfect for fins. Because Titebond shrinks, it doesn't make a pretty fin fillet. It does make a strong one, though. My approach: use Titebond for the first 1-2 layers of fillet glue, then switch to white glue to finish it.

White glue is chemically different than yellow glue--it does not shrink while drying. It is great for the top surface of fillets. It works fine for small rockets, but I would not recommend it for mid-power. For mid-power centering rings, polyurethane or epoxy are the better choices. Or, you could get radical and use medium CA, which would work great as well.

Personally, I am a fan of the wood glues for most construction, except centering rings. Stronger than the wood, lighter weight, and it doesn't cause chemical sensitivities.

 

[MikeyDSlagle]

That will only happen with thin wall Estes-type tubes. It won't happen with thicker tubes for HPR builds like those from LOC or Binder.

Ahh good to know and. On my Cowabunga I used Titebond 2 everywhere except CR to BT connection which got epoxy. Just didnt want the shrinkage rings and it didn't add significant weight.

 

[Banzai88]

As an extra measure of assurance, might want to sand throug the glassine layer. I do that regardless of glue used. I haven't had a glue joint fail or any of the dreaded paper peel.

 

[ThirstyBarbarian]

As an extra measure of assurance, might want to sand throug the glassine layer. I do that regardless of glue used. I haven't had a glue joint fail or any of the dreaded paper peel.

That's a good tip!

 

[T-Rex]

All of my builds in the last 3 years or so, LPR, MPR or HPR, have been wood, paper and Titebond. Even my centering rings I do with Titebond. I have never had one stuck, nor have I ever had a notable ring in a tube. I generally lay a thick bead for my rings. I know it prevents the sticking problem, not sure how I get by without the shrink rings.

As Banzai mentioned, remove the glassine where you want a bond. For motor tubes, I generally just strip it from the whole tube as it is easier/quicker. (just make sure you strip the tube BEFORE you fit your centering ring ID or they will be loose...)

YMMV