# 18 mm & 24 mm RMS - How practical?

### Help Support The Rocketry Forum:

#### bcdlr

##### Well-Known Member
I searched but couldn't find much information.
I'm a relatively new BAR and RMS is new to me.
Are the 18 mm & 24 mm RMS very practical? How long does it take to reload that kind of thing...
How does it compare price-wise?
How does it compare power-wise?
I've tried reading the documentation but didn't get much from it.
Am I just better off sticking with 'regular' motors unless I need a lot more power for something?
Sorry if this has been answered before or somewhere else...

#### Justin Horne

##### Well-Known Member
Just so you know, I've never used either (I use 29's) but:

I was wondering the same thing, so I asked someone at my club a few launches ago who does use them. He said they are great because some of the Estes kits are 'horrendously underpowered' and the aerotech composites really give them a great kick. He said he likes the use and good price. About the use: They assemble just like their bigger brothers, and the 29'd I use are easy. One thing he did comment on was that cleaning can be a tad difficult without a Q-tip.
From what it sounds like, go for it!

#### Stymye

##### Well-Known Member
I use both and have had good success with them,,they are just a smaller version of the bigger ones...great for the "tad too heavy" mod rocs!

#### n3tjm

##### Papa Elf
The 18mm and 24mm reload casing are my most used RMS motors. D9, D13, and D24 motors are great in Estes rockets like the Blue Ninja and Elimnator. The D13 is an AWESOME motor... the motor for choice in the Fat Boy (D24 does so nicely in that rocket too). I also enjoy putting D13's in Estes Snitch's.

#### cls

##### Well-Known Member
yeah, D13s are a lot of fun. try D13-7 in an Estes Patriot, or something long and skinny like a Custom Redline.

#### bcdlr

##### Well-Known Member
Originally posted by Justin Horne
One thing he did comment on was that cleaning can be a tad difficult without a Q-tip.
So, can you clean them and reuse them in the field?
How hard is it?
I'm supposing if you don't clean them bad things happen...or you can't get them back together...

#### bcdlr

##### Well-Known Member
Originally posted by n3tjm
The 18mm and 24mm reload casing are my most used RMS motors. D9, D13, and D24 motors are great in Estes rockets like the Blue Ninja and Elimnator. The D13 is an AWESOME motor... the motor for choice in the Fat Boy (D24 does so nicely in that rocket too). I also enjoy putting D13's in Estes Snitch's.
So, I'm guessing that all the motor reloads are 'hotter' than 'stock' SU 18 mm or 24 mm motors...
(BTW, thanks for the comments / help - keep it coming!)

#### Justin Horne

##### Well-Known Member
Yes, you can clean them in the field, I fly 29's all day long... The thing to cleaning a 29 is taking a wet wipe on your finger, and running it through to get all the residue off... For an 18, take a pencil or something, and put the wet wipe on it... Then run it through. Use the q-tip for the threads or any built up areas.

If you don't clean them, the case will be heavily corroded, and bad things will happen VERY soon.. Always clean with in one day, preferably ASAP post-flight. The longer you wait, the harder it is.
yes, they are a hotter motor, as they are composite, not BP.

#### n3tjm

##### Papa Elf
The RMS 18/20 is the easist reloadable motor to load. The RMS 24/40 is the hardest of all the reloadable motors by Aerotech to load. It has to do with the fine threads the 24 motor uses. If you tighten the forward closure all the way, there is to much tention to engage the aft closure. Trick is screw the forward closure on half way, and when ready, the aft closure half way to. Then screw on the fwd closure the rest of the way, followed by the aft closure. Another common problem with the 24 is a lot of times the liner does not fit. This is easily solved by removing a layer of paper off of the liner tube.

If you don't clean them, you will have trouble loading them (residue gets real hard, preventing the liner from entering the tube), possible seal problems, ejection carge reliability issues... and also... HCL eats aluminum... and a major byproduct of the fuel is HCL... and the casing is aluminum....

#### Stymye

##### Well-Known Member
yes ,some of them pack a serious kick

I put a D24 in my estes bomarc clone and it power-pranged 50 yards away and about 4 inches into the ground
..nobody saw the flight
it just "vaporised" from the pad. only a few seconds later we heard the thump...I won't try that again !

It helps to have a clean stable surface out of the wind to assemble them and to pour the ejection charge in.. plus it's easy to loose a small part if it fell onto the ground.

It takes some practice to memorise how to put one together so It helps to keep the instructions handy

If for some reason, you don't clean out the casing for even a day or two you can soak it in some 50/50 vinegar water for a couple hours or overnight even, and any leftover crust will usually dissolve.

#### Stones

##### Well-Known Member
Baby wipes are convenient, cheap, and real handy in the field. Initial cleaning with the baby wipe , then paper towel to dry off.

#### SpartaChris

##### Well-Known Member
I have a 24mm RMS and will be buying an 18mm RMS. There is something beautiful about putting an 18mm D-24 in a kit that would ordinarily get a C-6.

Plus you get a lot more power from the RMS kits. I have the Estes Saturn V and Phoenix kits which are seriously underpowered with D-12's. The 24mm RMS will allow me to put in a wider range of motors up to an F-39, all of which are the same size as an Estes D-12.

-Chris

#### rbeckey

##### Well-Known Member
You can get a pack of 24 mm E18 reloads for about the price of three E9 BP motors. Put one in a Big Daddy, Mean Machine or other 24mm mount bird and watch it soar out of sight! Also great in 6 & 9 inch saucers.

#### gerbs4me

##### Well-Known Member
I have the 24/40 casing, I love it, especially in the V-2. with a D12 its way underpowered, put in a E28, alot cooler flight

#### bcdlr

##### Well-Known Member
Originally posted by stymye
It helps to have a clean stable surface out of the wind to assemble them and to pour the ejection charge in..
So, the propellent is in powder form?
I just assumed it would be a solid 'chunk' you stuck in there. I wish I could see one better. I looked at the instructions but I didn't get much out of it. I will try and look again (or someone point me to the "right" instructions).
You guys almost have me talked into it. But will have to wait till I make a little more 'mad' money...
Where's a good place (read that cheap) to buy? $$And can you get the reloads on line without paying hazmat fees? How much for reloads?$$
Thanks for all the info - it's helping me to understand. I'm going to save all this off as a file even...

#### n3tjm

##### Papa Elf
No... The propellant and the delay grain are solid. the only thing powdered is the ejection charge. What he meant was the wind has a habbit of blowing parts off of your table into the grass.

There is a video on my website of me trying to load a H210R in strong wind... funny.

With the hobby RMS motors, you do not have to pour the ejection charge into the well. Just hold the ejection charge cap opened end up (so you don't have to defy gravity), hold the motor ejection well down, and press the cap onto the motor. Shake the motor (Thumb holding the cap down just in case) to settle the charge into the well. Forget to do this, and there is a good chance that the charge will not function.

Sometimes the ejection cap is too loose and wants to fall off. If this is the problem, remove the cap, set it in a safe place (so you don't loose your powder), and take a piece of masking tape, wrap it around the nipple of the ejection well. Make it as tight as possible. I usually use my finger nail to press the tape into the recess on the nipple. Then carefully pour rhe powder into the well, being careful not to get to muich powder on the tape. Tap the side of the case to settle the powder. Then pinch then ends of the tape together to deal it in.

TRF Supporter

#### SpartaChris

##### Well-Known Member
Originally posted by bcdlr
Where's a good place (read that cheap) to buy? $$And can you get the reloads on line without paying hazmat fees? How much for reloads?$$
Thanks for all the info - it's helping me to understand. I'm going to save all this off as a file even...
Magnum is about as inexpensive as they come and Ross is excellent at sending orders out that same day. He'll even call you with a tracking number. I recommend avoiding Discount Hobby Center though. There is a thread here about how crappy their service is. I also have a friend who delt with them so I have first hand experience by proxy..

As for prices, I bought my casing for $35. I bought a pack of F-12 and F-39 reloads for approximately$20 a piece. There are 3 to a pack. You can find these reloads for around $14 on line, but factor in shipping and my cost is roughly the same. There is no haz mat charge for 24mm reloads as they don't weight enough to warrant it. Hope this helps. -Chris #### powderburner ##### Well-Known Member I have wondered about these little RMS toys and you guys make 'em sound pretty good. What do you use for ignition? Taking a wild guess here, I'll bet you don't use the little Estes solar igniters. Do you make your own? What is the nozzle throat diameter (and what is the max size of the igniters)? #### SpartaChris ##### Well-Known Member Originally posted by powderburner I have wondered about these little RMS toys and you guys make 'em sound pretty good. What do you use for ignition? Taking a wild guess here, I'll bet you don't use the little Estes solar igniters. Do you make your own? What is the nozzle throat diameter (and what is the max size of the igniters)? The reloads come with copperhead ignitors, or you can use first fire jr's, though they are over priced. I currently make my own using two strands of network cable wire. They fit through the 24mm nozzle just fine, though I dunno about the 18mm yet. -Chris #### DynaSoar ##### Well-Known Member Originally posted by bcdlr So, I'm guessing that all the motor reloads are 'hotter' than 'stock' SU 18 mm or 24 mm motors... (BTW, thanks for the comments / help - keep it coming!) They're hotter than stock Quest/Estes style black powder motors beacuse they're APCP fueled. To see the difference for yourself, pick up an 18mm S/U AT D21-4, and put it in something you'd normally fly on a C6. Pick something strong because the D21 gives a hard, fast kick. For a 24mm S/U check out an Apogee E6. They have a 7.8 sec burn time, a slow looooong kick. They're only as big as an Estes C11 or D. When I saw what a composite S/U could do, I bought a complete 18/24/29mm RMS motor kit and a second 24mm. They're a little more work and S/U but the cost savings is worth it if you fly often enough. The cost will also serve to teach you the importance of making sure you're not overpowering, because they get very expensive to replace. I always flight test with a S/U first. #### n3tjm ##### Papa Elf Originally posted by OKTurbo Here's a link to some pictures of my RMS 24/40 loaded up with a F12-5J load. https://photos.yahoo.com/[email protected] ...go to the album titled "RMS 24/4.." Cool. You got some extra goodies with that reload kit. Notice the three grain spacers (short white tubes approx .5 - .75" long)? Well, The 24mm F motors do not use those. Those are for the E reloads (The D loads have a longer spacer tube). I hope some inexperienced person does not buy a E11/18/28 with a missing grain spacer. That would be bad news. (It probabily be fine with the 24mm load because the liner seats the nozzle, but fatal with the 29mm load... however... I would't try it...). Here are some good notes about reloadable motors. Sometime soon I will add more to this. https://n3tjm.crosswinds.net/Motors/Reloadable/RMS.html #### n3tjm ##### Papa Elf Originally posted by powderburner What do you use for ignition? Taking a wild guess here, I'll bet you don't use the little Estes solar igniters. Do you make your own? What is the nozzle throat diameter (and what is the max size of the igniters)? I don't like the copperhead igniters, so for the E18, E28, F24, and F39, I use Magnelite ML-12 wires, no fold, single dip. Works great all the time. For D9, D13, D15, D24, E11, and F12 loads, I make my own wires using some 32 guage twisted pair wire. I cut one srand so it is about half inch shorter then the other. Then I strip about a quarter inch of the insualtion of each strand. Using some needle nose pylers, I make a small tight loop on the lower strand. then I take a piece of nichrome, fold a hook in it, stick it in the loop against the angle in the L, and wrap it around the loop. I use a liberal amount of solder to hold it on (SOLDERING IS A MUST. It makes it more reliable, and does take less current to fire the igniter), then I wrap the nichrom around the strands, working my way up and over the top striped wire. Then I solder the nichrome to that. Trim off the excess nichrome. After it has cooled, and solder flux cleaned off, I dip it in Magnelite pyrogen. Works all the time, and works great for cluistering too. If you can find them, Firefox 32 gauge wires also work. Many people recommend Firefly igniters... I have used them... but the Magnelite igniters I never had a misfire (unless the motor is VERY VERY Old, or using a hard to light propellants like Redline, Red Rhino, or Green Gorilla). I had quite a few misfires with Fireflys. Also, I found they don't have a long shelf life after opening the pack. They don't work anymore . I have the same problem with quickburst igniters. Magnelites don't have this problem. #### aksarben10 ##### Well-Known Member Just a small tip - Make sure you use better motor retention then the Estes/Quest clip. The ejection charge on these reloads seem to pack a bit more punch then that of the BP motors. I have had the motors kick out the back and have had to upgrade the retention on all the models that I use the RMS systems with. For cleaning I use a dowel that is just smaller in diameter then the tube. First I use the dowel to push out the burnt leftovers then I put a baby wipe around the dowel and push that through a couple of times after that you clean the threads and its ready to go again only takes a minute or two. Scott #### Stymye ##### Well-Known Member good point, it's a good idea to tape ( I use ty-wraps) around the motor hook, a weak engine hook can have trouble holding the casing in place during ejection. #### OKTurbo ##### Well-Known Member TRF Supporter Tape or a tie-wrap on the Estes hook is a good idea, but you don't have to use all the black powder in the little red cap for the ejection charge either. If the ejection charge is a little too "lively" for a particular rocket....just use less ejection charge next time. BTW...I get most of my mail order reloads from Tim at Wildman...good prices...excellent service... www.wildmanrocketry.com John #### loopy ##### Well-Known Member ...for my 24mm casing. It's great for things like the Phoenix, Executioner, and Big Daddy. I've launched my Phoenix and Executioner on E-18's and they've been awesome flights! I also have a Prowler that I bashed for 24mm reloads, and that's got a composite 24mm reload D with it's name on it in the near future. As for price - 24m D reloads are really cheap - under$8 for a 3 pack in some cases, depending on where you get them. Great Lakes Hobbies has really good prices, and decent stock as well.

As for retention - I usually put a wrap or two of floral wire around the motor tube/hook once I install the motor, then twist the wire ends together until it's nice and tight - that motor ain't goin' nowhere!

Loopy

#### stevecarr

##### Well-Known Member
Cleaning is the easy part its the puttin it together that can take time. I put an E18-7 in an Estes Desert Storm Patriot I slightly modified. Talk about SPANK! They are a lot of fun to.

#### jcsalem

##### Well-Known Member
I'm bucking the trend here but the small RMS motors aren't worth it for me.

For underpowered rockets, I tend to enlarge the MM when building. Thus, my Big Bertha has a 24mm MMT, my Blue Ninja has an E-engine mount, and if I was building it again, I'd probably put a 29mm mount in my Executioner. So I don't need RMS to get enough oomph to power those rockets.

Looking at the cost of the motors, I tend pay around $3 for each D12, and$4 for each E9. This is cheaper than their closest RMS equivalent. Even when looking at replacing motors like the F20 or F21, the cost isn't much different when you consider the cost of the casing (how many fllights will you get in before losing it) and cost of your time to prep the casing.

Since I live in New England, good weather flying days on large open spaces are a rarity. On those days, I'd much rather be flying than prepping motors. I typically prep my HPR reloads the evening/morning before. During the launches, my kids need some level of supervision (they're 6 & 8) and prepping more than a couple RMS loads during the day is a pain. I'd rather get in two D12 flights rather than a single D13.

So that leaves as the main 18/24mm RMS rationale as having access to a greater variety of motors. It's also kinda fun to assemble your own motor. While these are definitely attractions, I haven't wanted to spend much of my rocketry $there. Obviously, HPR pretty much requires using a reloadable system. I also think the payback on a 29/40-120 casing is pretty good ($10 vs. \$14+ for a G launch).

If you're dying to try RMS and like to fly mid power and above, I'd definitely start with the 29mm casing.

-- Jim

Party Pooper