M1675 bonding

[watermelonman]

I got myself an M1675 and am looking forward to flying it.

The instructions say bond it, and I certainly will, but that tidbit sticks out as interesting to me. The M1670 blue, M1810 red, neither require bonding. Is the combination more volatile than either uniform motor? Would the blues overpressure the red? Or is it simply thrown in to the supplemental instructions so they can emphasize the order of the grains?

 

[markkoelsch]

Which case do each go in? The longer the motor the more likely grain bonding is needed.

 

[RocketFeller]

I found out that the L1590T needs to be glued into the liner on the morning of our launch. Luckily our vendor had an L850W reload (both are for the 75/3820 case) which does not require bonding.

 

[jimzcatz]

Gary just decided /recommended grain bonding for the L1590. You would have been fine.

 

[RocketFeller]

Gary just decided /recommended grain bonding for the L1590. You would have been fine.

That explains some things. Nobody else at the launch could recall that it was required (including some people with lots of experience) so it was a bit of a surprise to everyone. The grain bonding instructions came on a separate color-printed bright yellow sheet with "these instructions must be followed" written across the top. As I am new to 75mm motors in general I didn't want to mess things up...

 

[jimzcatz]

You did the right thing. I didn't know how new your load was. Seeing as the instructions had the addendum, failure to do so would have most likely worked ok, but would probably have voided any warranty in case of failure.

 

[RocketFeller]

You did the right thing. I didn't know how new your load was. Seeing as the instructions had the addendum, failure to do so would have most likely worked ok, but would probably have voided any warranty in case of failure.

It wasn't so bad in the end, the L850W made for a nice majestic liftoff. It was on the low end of sufficient thrust, but the rocket is very stable. I had already opened the L1590T, so now I have a reload ready for the next launch - and I know to glue it the day before!

 

[jimzcatz]

Why wait? And performance issues with doing it early. I have cases loaded for a very long time. Not specifically recommending it, but might be an option.

 

[Dave A]

I've had loads in the case since April, burned fine on Sunday. Hey, Jim , those were an AT -M1297 in an ex 4800n case, hub cap no spacer. Then my 9" Patriot with an AT-M1850 6-grain, in a Loki 8000n case, hub cap and CTI spacer with 3/4" cut off. All worked great.

 

[jimzcatz]

Dave, I recently flew L900 in a 6000 case cut down to 4800. Perfect flight, just not impressed with the L900. Maybe the L1040 will be nastier.

 

[Dave A]

That M1297 is an awesome 4 grain, big white/yellow flame

 

[Dave A]

Those 4 grains fit perfectly in a 6000n case with 1 CTI spacer, too.

 

[Dave A]

Yeah, I see, the L900 is just over 3800n the M1297 is over 5400, more bang for the buck.

 

[watermelonman]

For the record on the original question, a friend has informed me that the bonding is for safety in the face of the possibility that the heterogenous grains burn out at a different time.