My first RMS case....WTH?!?!?!

[MarkII]

I have always found the assembly instructions for RMS reloads to be simple and fairly straightforward. I have never had a problem putting one together and I have assembled reloads in all of the Hobby Line cases and in some 29mm and 38mm high power motors. The most important thing to do is to review and positively identify all of the parts on the parts list before you start. Once you know what part is what, the assembly is a breeze. I always follow the instruction sheet step by step, even with reloads that I have assembled several times. I typically put each one together at the field immediately prior to the flight (including for my level 1 cert flight last year) and have never had any difficulty doing so.

 

[Rocketbuilder]

Yeah, it keeps the ignitor from going in past the grain and floating in the grain spacer.

Wait, hold on. So there's space between the propellant grain and the delay element? Then what lights the delay?

 

[cwbullet]

I am sure the flames reach the delay when the grains ignite.

 

[MarkII]

Honest question not intended to start a debate... What is the attraction of the AT reloads (particularly 24 & 29mm) when they are apparently so time consuming to load? I only fly SU from AT and use CTI for everything else. I can load any CTI in less than 15 seconds without instructions but see people fumbling and spending a lot of time to get the AT motors (particularly small ones) ready to go. Since CTI doesn't have an 18mm line, I have considered getting the RT/AT 18mm cases but when I see a lot of threads like this and folks fumbling around at launches it makes me think twice.

1. They are not time-consuming to assemble, at least not in my experience.
2. Fumbling? Not here, and I'm a notorious klutz.
3. Availability.
4. Availability.
5. Availability.
6. Did I mention availability?
7. No Hazmat shipping charges for the ones that I have used. There aren't any on-site vendors at the launches that I attend, so I must obtain my reloads via online vendors and have them shipped to me.
8. Low cost of the reloads. That's a big one for me, with my meager budget. The motors are more expensive compared to CTI's, but you only buy the motor once. You buy the reloads over and over again. With CTI, you pay less up front for the motor, but you pay more (in the smaller reload sizes) each time you buy a reload. RMS: higher one-time cost, lower recurring cost compared to CTI. (This mainly applies to the smaller reloads.)

Don't get me wrong, though; I love CTI's motors. It's simply a matter of each brand having its own relative strengths. I like each brand for its unique qualities.

 

[rstaff3]

I take it one step further. No doubt, the regular clips need some supplemental tape to ensure the reload case is retained. But I like to add a couple wraps of tape for friction fitting as well. One of the guys I fly with, who mentored my L2, showed me that trick.

I don't do quite as thorough a job as when using only friction fit, but I take a little extra time and try to get the case snugly in the motor tube. That way, if the motor retention (clip) should fail, I don't lose my 30|40|60|100|xxx dollar case.

It's cheap insurance.

Doug

.

That's a great, simple insurance. I'll add this to my bag of tricks.

 

[cwbullet]

I like both AT and CTI. It all has to do with what you are used to using and your comfort level.

 

[MarkII]

I am sure the flames reach the delay when the grains ignite.

Right. The entire length of the grain ignites at once, and as soon as that happens, there is a wild, violent conflagration inside the motor case. (It's not any place you'd want to be.) As a result, even with the gap, the end of the delay grain is ignited instantly.

 

[rstaff3]

That is supposed to be masking tape, I can play with the color a little... from step 9 of these instructions:

"Fig-4: Place a small piece of masking tape over the slot on one
end of the propellant grain. (“E” reload only). NOTE: The tape
allows the proper positioning of the igniter when it is installed.
Insert the propellant grain into the liner tube with the masking
tape facing the grain adapter tube."

Thanks Rex...here is an updated exploded view then...

Glad I did this exercise...I did not realize all the details involved assembling these beasties! And I wasn't aware that 18 mm, 24 mm, and 29 mm are that different.

Good job!

 

[MarkII]

That's a great, simple insurance. I'll add this to my bag of tricks.

Two words: zip ties.

Holds the hook against the motor and prevents it from being sprung out by the recoil from the ejection charge.

 

[Barracuda]

Also as a side note I put the tape on the grain first then push it up into the liner that way the tape edges are inside the liner and won't get pushed up or out by the igniter

 

[MarkII]

That's what I generally do also.. I bought a package of 3" X 4" ziplock bags at either Walmart or Michaels. 100 bags for a couple of bucks.

I write what motor it is on the bag with a Sharpie and then repackage the pack of reloads into 3 separate ziplocks. I usually then put the 3 packages into a larger ziplock with the instructions but I have left the bigger bag unzipped and have found a loose motor in the bottom of my range box.

Having what motor it is written on the bag sure helps.

It also helps with cleanup. After flying, I remove both closures and push the expended motor, by the nozzle, into the ziplock I just used. Then after giving the case a quick cleanup with a baby wipe, I put the baby wipe into the bag and zip it up. I then have a trash packet that is not going mess up my range box until I can find a trash can.

Great tip, Bob. I'm adding it to my routine.

 

[cwbullet]

Also as a side note I put the tape on the grain first then push it up into the liner that way the tape edges are inside the liner and won't get pushed up or out by the igniter

Good idea.

 

[NAR29996]

Two words: zip ties.

Holds the hook against the motor and prevents it from being sprung out by the recoil from the ejection charge.

+1 on the zip ties!

 

[cwbullet]

+1 on the zip ties!

+2. Zip ties and masking tape are the 2 most useful items in your rocket box.

 

[jimzcatz]

Heres one for you oldtimers. I remember when the 40/120 was first introduced the instructions had the propellant grain in the forward end of the liner tube. Of course doing it this way you pretty much had to build the ignitor into the motor( which I do anyway cuz its easier). I guess after numerous complaints on how hard it was to find the slot with the ignitor Gary changed the instructions. Anyone else remember this?

 

[cwbullet]

Heres one for you oldtimers. I remember when the 40/120 was first introduced the instructions had the propellant grain in the forward end of the liner tube. Of course doing it this way you pretty much had to build the ignitor into the motor( which I do anyway cuz its easier). I guess after numerous complaints on how hard it was to find the slot with the ignitor Gary changed the instructions. Anyone else remember this?

I do not, but I would have to say I am glad he changed it.

 

[luke strawwalker]

Right. The entire length of the grain ignites at once, and as soon as that happens, there is a wild, violent conflagration inside the motor case. (It's not any place you'd want to be.) As a result, even with the gap, the end of the delay grain is ignited instantly.

Unless you get grease on it....

Later! OL JR

 

[cwbullet]

Unless you get grease on it....

Later! OL JR

I believe it warns against that in the instructions.

 

[luke strawwalker]

I believe it warns against that in the instructions.

Yep, doesn't mean it doesn't happen though... OL JR

 

[Pem Tech]

Same here....
My first MPR launch was with an AT 29mm 40-120, which I built by myself without adult supervision, and have had no issues other than tight delay grains, since then. Now I did have an issue with a 24mm RMS, all the components were tight and I didn't screw the fore closure on as far as I should have. Needless to say, blow by, whoosh, poof, flames and fiery death.

Now I find myself using CTI motors more often because of the ease of cleanup but the complexity of AT reloads is not an issue for me.

I have always found the assembly instructions for RMS reloads to be simple and fairly straightforward. I have never had a problem putting one together and I have assembled reloads in all of the Hobby Line cases and in some 29mm and 38mm high power motors. The most important thing to do is to review and positively identify all of the parts on the parts list before you start. Once you know what part is what, the assembly is a breeze. I always follow the instruction sheet step by step, even with reloads that I have assembled several times. I typically put each one together at the field immediately prior to the flight (including for my level 1 cert flight last year) and have never had any difficulty doing so.

 

[cwbullet]

Yep, doesn't mean it doesn't happen though... OL JR

Yep. I have seen a lot of things happen that are made because someone left out a part or step in the instructions.

3 Favorites:

1) Wrong size case (too large)
2) Left out a spacer or o-ring
3) Complete left out the case (CTI)

Usually this results in flames.

 

[jimzcatz]

Something to remember with ALL Aerotech RMS loads, be it hobby or High Power. Always, I repeat ALWAYS make sure the forward closure is on all the way. If the rear does not go all the way thats not a big issue, as long as you seat it as far as it will go. This comes from Gary R personally several years ago. I have found that if I tighten the forward first, and then the rear they will usually seat properly. I have no blow-by issues...ever.

 

[rocketguy101]

I played with the SolidWorks exploded view animation...I think I have this in the right sequence according to the instructions...

[video]https://www.flickr.com/photos/75773285@N07/7586292328/[/video]

 

[Eric1]

I played with the SolidWorks exploded view animation...I think I have this in the right sequence according to the instructions...

[video]https://www.flickr.com/photos/75773285@N07/7586292328/[/video]

Looks right to me. More crap in that little case than stuffed in a christmas turkey!

 

[cwbullet]

Pretty cool. Looks right to me.

 

[MarkII]

"So I say to you: Ask and it will be given to you; seek and you will find; knock and the door will be opened to you." (Luke 11:9)

I downloaded these two documents from the AeroTech website a couple of years ago. Dig around in the Resources tab at the AeroTech site, and you'll likely strike gold. These were in the Catalogs, Flyers, Data Sheets & Thrust Curves subsection. I have attached the Hobby Line guide, but the High Power guide is too large to include as an attachment. You can obtain it from the link provided below:

Model Rocket RMS O-Ring, Spacer & Insulator Guide
High Power RMS O-Ring, Spacer & Insulator Guide

 

[Rocketbuilder]

I played with the SolidWorks exploded view animation...I think I have this in the right sequence according to the instructions...

[video]https://www.flickr.com/photos/75773285@N07/7586292328/[/video]

Awesome! Thanks! I sure hope it's right, since I'll be referencing it for my first reload...
If it's wrong, somebody speak up!

 

[rocketguy101]

Awesome! Thanks! I sure hope it's right, since I'll be referencing it for my first reload...
If it's wrong, somebody speak up!

i did not show the igniter in this version. the igniter goes in before you insert the nozzle. this is stated in the instructions, so read them along with following this animation. I did a better job w/ the 29/40 "G" model, and will revise the 24mm (that is why I have "draft" in the descriptions )

 

[Rocketbuilder]

Oh true. I would almost certainly have caught that, comparing it to the directions that come with the motor, though.
Keep up the great work!

 

[rocketguy101]

He should make one for each series of motors (some will be the same), make a new post, and have the mods sticky it. (I'm good at volunteering work from other people )

OK, I have the 18/20; 24/40; and 29/40-120 modeled up. How do you make a sticky post?