Grain Bonding an M1550R

[davidshewitt]

I have an AeroTech M1550R that I plan to fly in my full-scale Arcas at BALLS. There is no insert with grain bonding instructions. This is unlike the other 75mm motors I've flown (M650W and L2200G), each of which had different grain bonding instructions requiring different glue.

* Do I need to grain bond?
* What adhesive and method should I use if so?
* What does grain bonding do for the motor?

 

[rharshberger]

I have an AeroTech M1550R that I plan to fly in my full-scale Arcas at BALLS. There is no insert with grain bonding instructions. This is unlike the other 75mm motors I've flown (M650W and L2200G), each of which had different grain bonding instructions requiring different glue.

* Do I need to grain bond?
* What adhesive and method should I use if so?
* What does grain bonding do for the motor?

I previously asked this same question, and the answer was, its not necessary to bond the grains to the liner in the M1550R but it also doesn't hurt anything. Grain bonding helps the motor resist the acceleration forces and keeps the partially burned grains from collapsing under that acceleration.

 

[cerving]

I'd bond it anyway, it can't hurt. Elmer's Glue All Max is the glue of choice for AT motor grain-liner bonding. What it does is to keep the grains from moving in the liner as they burn... which would be bad for a motor that size.

 

[davidshewitt]

I'm going to go ahead and bond it. I have some Glue-All MAX that I had ordered for AT motors.

 

[eggplant]

Just to make sure things end up well, follow the instructions from the L2200G, NOT the M650. The M650 is a moonburner grain that has to ship in multiple pieces for regulatory reasons. The instructions have you bond the grains to the liner and the faces to each other to effectively return it to the single large grain it is supposed to be. The M1550R is a BATES motor that relies on the grain faces being exposed like the L2200G. Even if AT doesn't say to bond the M1550R, it can't hurt, and makes for a cleaner burn with a significantly lower chance of spitting a casting tube.

Probably already clear from the other responses, but I wanted to make sure!

 

[StreuB1]

FWIW, I find the Loki method of grain bonding to be a lot easier, less messy, and eliminates the chance of rolling up an o-ring or the o-ring shifting inwards. Just need a roll of cellophane tape is all. Very easy procedure and it works every time.

 

[prfesser]

FWIW, I find the Loki method of grain bonding to be a lot easier, less messy, and eliminates the chance of rolling up an o-ring or the o-ring shifting inwards. Just need a roll of cellophane tape is all. Very easy procedure and it works every time.

Link to .docx file

At first I thought you were saying that epoxy wasn't required, only cellophane tape. Had to find the instructions and read them. I Am Not A Smart Man...

 

[StreuB1]

Link to .docx file

At first I thought you were saying that epoxy wasn't required, only cellophane tape. Had to find the instructions and read them. I Am Not A Smart Man...

I should have been more explicit to be honest! LOL Rereading that, it does sound like all one needs is some cello tape! Gosh, I wish!

 

[krislhull]

I asked this same question about the M1550R prior to my L3 cert attempt with the motor a few weeks ago. One of my TAPs agreed that it isn’t a bad idea, but definitely not required. I did not bond them, and had no issues at all.

 

[Wayco]

I've done it both ways, and had good results every time. Did get some chunky sounds once when it wasn't glued.....

Link to .docx file

At first I thought you were saying that epoxy wasn't required, only cellophane tape. Had to find the instructions and read them. I Am Not A Smart Man...

Not sure about that last statement, but you are definitely self-deprecating.

 

[davidshewitt]

Link to .docx file

At first I thought you were saying that epoxy wasn't required, only cellophane tape. Had to find the instructions and read them. I Am Not A Smart Man...

I might try the Loki method (but with Glue-All MAX since it's an AT motor). The past times I've done grain bonding, the glue is almost set by the time I'm done and I almost wrecked the motor.

 

[davidshewitt]

One more question, should the grain spacer o-rings be greased? The AT instructions have been ambiguous on that.

 

[krislhull]

One more question, should the grain spacer o-rings be greased? The AT instructions have been ambiguous on that.

No, do not grease the grain spacer o rings. The directions specifically state to not grease them.

 

[jbr]

I used a M1550R, had to peal the outer paper and just put the grains in, no bonding needed

 

[JackC]

Yeah, I've flown that motor many times and never used grain bonding. I wouldn't bother doing it because that motor doesn't run hot like the other motors that require grain bonding.

 

[firemanup]

I’ve flown several M1550Rs one of my favorite reds for my Deadpool rockets, I’ve never bonded and never had an issue.

 

[davidshewitt]

I grain bonded and flew this motor in my Composite Warehouse Arcas to 11,000' at BALLS. No issues with the motor, and recovery deployed perfectly.

 

[ZEDL1]

Link to .docx file

At first I thought you were saying that epoxy wasn't required, only cellophane tape. Had to find the instructions and read them. I Am Not A Smart Man...

You definitely are... I, and many, pay attention the man, you, behind the curtain...

 

[ZEDL1]

You definitely are... I, and many, pay attention the man, you, behind the curtain...

Please add the word "to". It's late and I'm' tired, Sorry Terry.

 

[Steve Shannon]

Please add the word "to". It's late and I'm' tired, Sorry Terry.

For a period of time you can go back and edit your posts, you know. At the bottom of the post is a spot to click.