Could I use Liquid Nails and not epoxy - Northern Colorado Rocketry

This topic has 15 replies, 9 voices, and was last updated 15 years, 2 months ago by Steve Jensen.

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November 23, 2009 at 3:21 pm #40849
MarkC
I wanted to know if liquid nails could be used in level one and two rocket construction. Liquid nails in very very stong and is great for bonding wood. It is flammable though. Or is epoxy still the best way to go.
November 23, 2009 at 9:09 pm #51723
mule
Participant
Statement removed due to foot in mouth condition, or is it brain fell out before hands typed…. DOOOOOH
November 23, 2009 at 10:41 pm #51724
Steve Jensen
Participant
I’ve had some success using PL Premium polyurethane glue. I built a rocket fin can as described by Edward: See the Forum “Construction Help” Thread titled “Fin Options”.

The construction technique described by Edward seems to work, but I’ve only tried it through I Motors.

I’ve a rocket ready to launch with some big J motors that I built using his technique. My variation is that I foamed the fin can with a urethane foam, which should readily bond to the polyurethane glue.

Th PL Premium polyurethane glue (I got mine at Home Despot) is really easy to use when setting up a fin can.

Now let’s see if the fins come off my new build (a PML Tethys). Hopefully the weather for December will let me after the November incident…
November 24, 2009 at 2:00 am #51725
mule
Participant
Interesting. You learn something new every day. Is the PL the same poly base as LN?
November 24, 2009 at 2:43 am #51726
MikeS
Moderator
Here is the MSDS on PL Premium.

http://www.stickwithpl.com/pdf/PL%20Premium%20msds.pdf

All the temperature ratings seem to be before curing..??
They are pretty low. Flash point is 250 Deg.

I have two tubes that are going to be used on my next
8″ rocket.

I used it on a bulkhead and coupler of My Mad Dog. Sets
real hard. Nice working with something a little less runny.

Ed has used it on some pretty heat intensive projects. I
am sure it is what You could call ‘Ed Tested’
November 24, 2009 at 4:37 am #51727
edward
Moderator
I love PL Premium for fincans. Makes construction a snap. I had constructed Bunny Thumper that way (5.5″ rocket, 1/16″ G10 fins). It worked great until I spacked it at Hartsel. The fins pulled off from the paper tube, but the PL is still firmly bonded to the G10. I found the weak component. My other rocket I used PL Premium for the fillets, then went over it with 2″ strips of glass that I then used epoxy on. Those have not come off yet.

Remembering from my materials science classes we used Liquid Nails and PL Premium as well as a few other subfloor adhesives and did pull tests. The PL Premium was 4x as strong as the next competitor. The 3/4″ OSB would always delaminate in the middle of the sheet with the glue staying firmly attached to the floor joist. When the floor joists were TJI’s either the 3/4 OSB would delaminate or the top flange of the TJI would delaminate.

I was also very impressed when I used PL Premium to glue 2L soda bottles (PET plastic) together for water rockets. The bottles would delaminate before the glue gave up the ghost.

For bulkheads, centering rings and couplers it works very well. Doesn’t run, easy to apply and sets up nicely. I don’t think you’ll get better adhesion being that it is paper to wood.

Motors are required not to exceed 200C (392F) during and after the burn. I know my hybrids go to 81C (178F). Some get warmer, some are cooler. I’m not worried about it giving up during boost – the motor temps generally haven’t transmitted through the motor mount yet. I’ll have to go back and ask my professor if I can do some tests of adhesives at elevated temps.

Edward
November 24, 2009 at 1:39 pm #51728
SCOTT EVANS
I wanted to know if liquid nails could be used in level one and two rocket construction. Liquid nails in very very stong and is great for bonding wood. It is flammable though. Or is epoxy still the best way to go.

Just try it so we will all know! 😉
November 24, 2009 at 1:58 pm #51729
Adrian
Participant
Thanks for the useful info, Ed.

-Adrian
November 24, 2009 at 6:09 pm #51730
mule
Participant
I second that.
My apologies for jumping the gun a bit. 😳
November 25, 2009 at 1:25 am #51731
John A. Wilke
Participant
Edward, I had once heard the 200F limit on motor temps. I assume that is the surface temp (duh) and it is taken several places around the circumference of business end?

I ask because I’ve always worried about moonburners getting so hot nearest the area along the offset core. The way I see it, if a motor burns for 8-10 seconds and the core is close to one edge, then the area nearest that offset core will be subject to astoundingly high temps — while the opposite side will stay very cool. I can’t see the surface temp on the side nearest the core staying that low. If one AVERAGED the temps around the circumference, maybe — but not near the core.

Am I missing something? does the liner soak up that much heat energy?

As I usually fly minimum diameter, I always orient the core between fins and I like to use carbon airframes on moonburner shots, as I know carbon is a better insulator than glass.

Thoughts?
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