The G71R was a little before my time so I am not sure what the exact issue was but I think there was a delay issue so we stopped making them. Maybe other TRF members can recollect better than I can but it was something like that. That is why a new red load for the 29/40-120 is such a highly requested load. We are developing new loads for the hobby line now and a red to replace the G71R is on the list.
The G71R was a little before my time so I am not sure what the exact issue was but I think there was a delay issue so we stopped making them. Maybe other TRF members can recollect better than I can but it was something like that. That is why a new red load for the 29/40-120 is such a highly requested load. We are developing new loads for the hobby line now and a red to replace the G71R is on the list.
I think the problem with the G71R was some chemical in the propellant grain was contaminating the delay grain. The problem got worse as the reload aged. The suggested work around was to use new delay grains packaged separately from the propellant grain.
I believe you are correct, Karl said something in an email about a similar problem I had with an older (10 year or so) I218R that had a "very fast" delay (ejection charge about 2-3 seconds after motor burn out). One of the chemicals could migrate over time from the propellant to the delay grain, accelerating the delay grains burn rate iirc.
This post is definitely not to trash AT. I simply want to know if anyone has any input as to why this may have happened. I know the 29mm G71R-7 is an old motor, but I've launched three of them prior to today and never had a problem. Bad delay grain, ignitor not installed all the way, or maybe even grease on the delay grain? I have no idea. If anyone can share some input, I'd appreciate it. Thanks! https://youtu.be/qKD2t6Jl3mQ
Anyone know the powder weight included for ejection charge in 38, and 54mm DMS motors? Is it 1.5 grams for 38mm and 2 grams for 54mm?
Hi Charlie;
Just built my first 98 AT motor for my L3 this weekend and I wanted to point out 2 very small things on my 98 /10249 assembly of an M1939.
In the instructions - Fig 6. Don't say anything or show in the diagram the thin propellant grain O-rings. I watched the video and knew about them - but noted the instructions didn't say anything about it.
View attachment 304381
Also the smoke grain insulator was oversized by about 0.007" and wouldn't fit into the forward closure which required sanding.
Also in reading the Aerotech Grain Bonding document - it appears the loads needing bonding are the blue. And super thunders - however the N2000W is also on that list which is a load I may plan on flying. Question is - why not just grain bond all the loads in this size? Noticed in the instructions that a load may have slop in the grain length allowing them to move in the motor and that is OK, so grain bonding - Is it a matter of fit and thrust?
Thanks - looking forward to the power of the M1939!
PS the motor went together fine and the video made it a breeze.
75 & 98mm RMS Reload Kit Grain Bonding Advisory
....
Therefore, we are advising all our customers to bond the grains of the following reload kits into
their liners with Elmers Glue-All Max. This is a polyurethane glue with minimal foaming and
expansion to prevent the liner from cracking during cure, and has a long working time. The
bonding process itself takes only a few minutes after which the glue should be allowed to cure
overnight before use.
...
View attachment 303926
I am having a hard time finding Elmer’s Glue-All Max™ locally. I don't have time to order it before this weekend. Can I use 30 minute epoxy instead? Or an alternate glue?
I am having a hard time finding Elmers Glue-All Max locally. I don't have time to order it before this weekend. Can I use 30 minute epoxy instead? Or an alternate glue?
I am having a hard time finding Elmers Glue-All Max locally. I don't have time to order it before this weekend. Can I use 30 minute epoxy instead? Or an alternate glue?
This complaint is 100% accurate. We are working on a matrix right now but that is a small step in my opinion. A larger concern of mine are the websites. It is a large project to be sure but one that we, as an industry leader, need to correct. In fact, here is the list of my current priorities:
-catalog
-website(s)
-hardware
If I had to prioritize them they would be 1a, 1b and 1c. Excellent point. I would say to expect the improved websites by mid-late June.
Is the N dark matter going to be available soon? Trying to convince my dad out would be a good choice to do an L3
I have sent a MESS report on the failure of an Aerotech DMS J250W-14A at Midwest Power this past Sun. 11/06/2016. I am sending a warranty request to Aerotech.
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