Quantcast

Why CA is Not Real Good for HPR MMTS

The Rocketry Forum

Help Support The Rocketry Forum:

Hospital_Rocket

Well-Known Member
Joined
Dec 25, 2003
Messages
3,990
Reaction score
1
1. Take a 38mm LOC Cyclotron

2. Assemble the 38-29mm reducer using CA

3. Insert G80 Blue Thunder

4. Push Launch Button.

5. Presto - Roman Candle....


OUCH!
 

gerbs4me

Well-Known Member
Joined
Sep 21, 2009
Messages
3,102
Reaction score
3
Location
Iowa
definate ouch
too bad, is the inside of the BT charred bad?
 

powderburner

Well-Known Member
Joined
Jan 18, 2009
Messages
7,356
Reaction score
4
I have come to really like CA as an agent for reinforcing cardboard and other fibrous materials. Soak that stuff into a wimpy piece of paper and you get instant beef-up.

However, CA is a relatively brittle material. As the sole adhesive between two structural parts, you are gambling with your rocket in any power class.

Does anyone have any experience trying to use CA together with some chopped glass fibers? (I mean the kind of fibers some guys use to reinforce epoxy)
 

Hospital_Rocket

Well-Known Member
Joined
Dec 25, 2003
Messages
3,990
Reaction score
1
Originally posted by gerbs4me
definate ouch
too bad, is the inside of the BT charred bad?
Stangely enough, not really. I think the motor went through so fast that the damage was minimized. The only thing I could find was a 1" zipper where the chute tried to pull the BT off the pad.
 

Stymye

Well-Known Member
Joined
Jan 21, 2009
Messages
7,568
Reaction score
4
I like it for hardening and tacking things but, like you said >>>cya is not a structural adhesive<<<, especially on a high power motor mount. ........ :confused:
 

Ray Dunakin

Well-Known Member
Joined
Jan 9, 2003
Messages
1,018
Reaction score
0
What kind of CA did you use to construct your motor adapter? The thick (aka "slow") kind is the stuff you need.

I use nothing but CA to build all my high power rockets. I've also used it to assemble motor adapters. Currently I have several 2.6" diameter rockets with 38mm adapters in 54mm motor tubes.

Here's how I assemble a motor adapter:

I position the centering rings on the motor tube, then dribble a little thin CA on the joint to tack the rings in place. Then I add a fillet of thick CA on inner side of each ring. Next I put the larger tube over the centering rings, and tack it in place with thin CA, followed by a fillet of the thick stuff on the outer sides of the rings.

This has worked fine for me so far.

When assembling the rocket itself, I always mount the fins to the motor mount tube. Not only is this create a tough, durable fin assembly, but it also means that the centering rings don't have to take the full load of thrust.
 

Hospital_Rocket

Well-Known Member
Joined
Dec 25, 2003
Messages
3,990
Reaction score
1
I used thin CA for the adapter. what I did was put a light coat where the external thrust ring would go ans then after it was in place flood the exposed ends to soak the material. My only theory is that the CA did not adhere well to the glassine surface of the tube.

A
 

r1dermon

Well-Known Member
Joined
Mar 1, 2009
Messages
2,297
Reaction score
2
man, i only use epoxy. CA is too iffy. i've glued fins on with that zap stuff and lost them on B motors. crazy stuff. epoxy is the way to go. tac with 5 min, fillet with 30min epoxy, thats going to be one strong joint. plus, its cheaper(i think) the stuff i buy is anyway.
 

GL-P

Well-Known Member
Joined
Jul 15, 2004
Messages
1,617
Reaction score
0
I find the fumes for CA too intoxicating for heavy use. West System Epoxy has very little smell.

Why use CA? It seems too brittle for my tastes. I also hate getting my fingers glued to stuff. Epoxy is a lot more forgiving.
 

Lugnut

Well-Known Member
Joined
Sep 23, 2004
Messages
412
Reaction score
0
I'll use it on things like plastic nose cones, where it holds great, but otherwise, I prefer 'normal' glues (Weld Bond) or epoxy for tough stuff. I will keep it in my field box for emergency repairs if I think the joint can deal with a CA bond (if only temporarily).

That IS a cool picture though ;) Who was it here who said, by means of explaining model rocketry to a significant other, "either it goes real high and makes a lot of noise, or it blows up. Either way I win".

Lug
 

r1dermon

Well-Known Member
Joined
Mar 1, 2009
Messages
2,297
Reaction score
2
i notice the motor is still thrusting in the picture...what became of that?
 

lalligood

Well-Known Member
Joined
Jan 21, 2009
Messages
1,975
Reaction score
0
Regardless of the size of the rocket, you can't beat yellow wood glue (aliphatic resin) when the parts being joined are cardboard and/or wood. No smell & cleans up with water too! :cool:

And I'm not fond of CA either except when used *very* sparingly & in small amounts...like it was intended!
 

r1dermon

Well-Known Member
Joined
Mar 1, 2009
Messages
2,297
Reaction score
2
not for rocketry anyway. i use it on my traxxas 4-tec gas RC, that stuff holds like crazy on those rubber tires. but in rocketry, with the forces that some motors produce, im going for the strongest stuff available.
 

Hospital_Rocket

Well-Known Member
Joined
Dec 25, 2003
Messages
3,990
Reaction score
1
Originally posted by r1dermon
i notice the motor is still thrusting in the picture...what became of that?
What you see is right about at apogee. It landed about 25 feet away and did the "loose motor dance of death" with the patented "ejection charge encore."


At this point, Would anybody buy the line that this was really a test of a new guaranteed to deploy ejection system?
 

Stymye

Well-Known Member
Joined
Jan 21, 2009
Messages
7,568
Reaction score
4
lol, I like that ......." loose motor dance of death"
well atleast your upbeat about it.

looks pretty tore up tho can it be repaired?
 

Hospital_Rocket

Well-Known Member
Joined
Dec 25, 2003
Messages
3,990
Reaction score
1
Actually all I have to do is fix the 29mm adapter, and repair a 1" zipper. Then we shall try this again. The Ring Thing will fly!

Actually I wanted to fly it on a Loki H144, I was just afraid of losing the casing in the wind. Had I used it We would not have had the great picture.
 
Top