I don't know which RMS to get. The ones I am cosidering are the 18/20 (in an adaptor usually), 24/40, 29/120, and 29/40-120. From what I have heard, the 18/20 has cheap reloads but no variety of reloads, the 24/40 has serious reliability issues (bottom of page). The 29/120 has a real "kick in the pants G" but no variety. However, I can use the closures on the 29/60, 29/ 100, and 29 mm. high-power reloads (I won't quickly outgrow the closures. I probably cert on this thing if I get it on a great (I've heard) motor: the H128. The 29/40-120 has plenty of motor choices and is very reliable but is a bit more bulky than a 24/40 and you cant cert on it either. Another thing I need to consider is kits: LHS only carries 13 mm, 18 mm, and 24 mm. However, has anyone heard of using Quest T-30 as MMT for 29 mm. rocket (I use Quest T-25 for BP D's.

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Always look on the bright side of life.

What goes up must come down (at least to the treetops)
Death awaits you all with big nasty pointy teeth. "

First off, regarding the RMS 24/40: it's interesting that you focus exclusively on the the three negative comments at the bottom of the "Guest's Opinion" section, while ignoring the four positive ones above them. Are you just a pessimist who will only believe the worst about everything, or are you someone who selectively screens out information that doesn't conform to his predetermined conclusion? I sincerely hope it is neither, but those are the impressions I got from the beginning of your post. Perhaps it was just a poor choice of words. I hope so, and I would like to give you the benefit of the doubt. I would prefer to think that you are a new flier who was just scared off by the appearance of those negative reviews. Please reassure me about that.

The fact is that the RMS 24/40 is a very popular motor, and that is precisely because it is so reliable and easy to use. I have participated on YORF and TRF for the better part of three years, and I have been a member of the oldrockets Yahoo! group for much longer than that, and I cannot remember ever reading any posts that alleged or even suggested that there was anything unreliable about the RMS 24/40 motor. That motor has a whole lot of fans in the rocketry community. Believe them. The three negative comments at the end of the EMRR review are not representative of most user's experiences with this motor.

My friendly advice would be to buy all three of the "hobby line" RMS motors: the 18/20, the 24/40 and the 29/40-120. You can often get them as a set, which will save you a few bucks. You can find great deals on them at Aerotech's Valuerockets.com website, or from any vendor who sells the Rouse-Tech versions of these motors. (Rouse-Tech is a licensee of Aerotech, and its motors are identical to AT's, but are priced lower. R-T's motors come with very durable anodizing, and they are hugely popular.) Many people who can only afford to buy one at a time, or who want to test the water a little before jumping in head first, start with the 24/40 case, as a matter of fact. But once you try one case, you will want the others. The 29/40-120 case is extremely versatile, but it requires larger rockets and larger fields. I have heard that the E reloads for it are not especially popular though, because of the weight penalty. The 18/20 case is considered to be very easy to load, and it is quite useful for larger or very draggy rockets that have 18mm mounts (such as the OOP Estes Outlander).

The three smallest "high power-style" 29mm RMS motors are optimized, as you noticed, for very specific reloads. Welcome to the world of high-power motors. With a few exceptions, that is going to be true for the rest of the RMS line (and similar products from other manufacturers) right up through the 98mm sizes. You will eventually be building (and possibly designing) rockets that also will be optimized for specific motors (just like the pros do!), at which time these cases will become useful to you.

Hope this helps, and sorry for coming down so hard on you at the beginning of this post.

One more thing: I have found that Semroc Astronautic's Series 115 (LT-115) tubing is perfect for use in 29mm motor mounts. Semroc also sells centering rings that adapt this tubing to most popular body tube sizes.

MarkII

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SAM # 0011

Another "one more thing": what makes an RMS motor cost-effective is not how many different reloads are available for it. What makes it cost-effective is how often you use it with the reloads that are designed for it. The RMS 18/20 motor, for instance, is still a good deal even though there are "only two" reloads for it (but see below). There are many kits that have 18mm mounts that could really benefit, or at least would be truly impressive, if they were flown on D motors. The 18/20 case gives you that option. If you only load it with D13 reloads, for instance, it becomes very economical if you have several rockets that you like to fly on that motor.

Also remember that we are accustomed to thinking of, say, Estes D12-3's, D12-5's and D12-7's as separate motors. Well, the same thing is true of reloads, too. For the RMS 18/20 case, there aren't just two different reloads - there are actually six! They are the D13-4, D13-7, D13-10, D24-4, D24-7 and D24-10. The RMS 18/20 motor is more versatile than you may think!

MarkII

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SAM # 0011

The D13 is a wonderful reload. I usually only get to fly it for competition, but I picked some more up recently.
As far as the 24mm/40 casing, I really like the E18 reload.
As for the 18mm/20 case, Gary recently asked out opinion about bringing back B and C reloads in addition to other D reloads. Just a matter of time and money.

Chas

Don't forget to buy one or more of the NEW(ish) 24mm casings:


24/60

http://www.valuerockets.com/product...id=12&itemid=32

Same outside diameter to fit 24mm tubes, but longer to match the Estes E9 motor. Different and thicker casing wall and different threads - and therefore different forward and aft closures. Able to withstand much higher operating pressures. They have promised that there will be additional loads for this casing in the not-so-distant-future.

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-Fred Shecter NAR 20117 (L2)
Southern California Rocket Association, NAR Section 430

I did get all three and would make the same recommendation. I have made about 20 to 30 flights with the above AeroTech hardware and have had no motor disasters to date. Here is where I got mine:

http://www.redarrowhobbies.com/weekly_specials.htm

My biggest fear is forgetting to install the BP ejection charge. For this reason I put all the motor parts into the box and after building I shouldn't have any left over.

Actually, the one I use the least is the 18/20. Be sure to test fit the assembled motor hardware inside the rocket before you get to the field. I had interference on my Estes Mercury Redstone at the end of the motor mount where the hardware tried to get through the thrust ring. Things in the rocket might need slight alterations to accommodate the hardware.

The 29/40-120 hardware has many performance options. From mild to the G76G with 33+ lbs of peak thrust. The F40 and G64 are classics for the 29/40-120.

My recommendation is to find someone that is familiar with reloads and have them assist you. After you do your first couple of motor builds as a student, then do your solo build. Just a thought. Regardless, just go slow when you build and have fun.

Typically, Blue Thunder propellant is the easiest to ignite, and ignition can be a pain with composites.

Your first composite rocket launch will be a rush, with almost the same excitement as your first rocket launch (at least mine was). Fire, noise, smoke, and speed.

Greg

There are FOUR hobby line casings.

http://fourlights.ytmnd.com/

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-Fred Shecter NAR 20117 (L2)
Southern California Rocket Association, NAR Section 430

I think the 24/40 and 29/40-120 are good investments. They each offer a wide range of impulses and propellant types. I find the 29/40-120 much more flexible than the 29/120.

With the reduced costs of the 18/20 on the valuerockets.com site, I have recently added that to my collection as well.

I have heard of folks flying 29mm SU motors in T-30 based rockets - ie, in minimum diameter configurations. A couple wraps of tape help to seal around the motor. Back when Quest kits were very inexpensively available at Hobby Lobby, a popular setup was to get a 30mm based kit and over power it with a 29mm SU motor - sort of a fire and forget flight. I can't remember the preferred kit, but it was an E2X/RTF sort of thing.

That said, I wouldn't use the T-30 as a motor tube in rocket. IMO, you're better off using 29mm motor tube. Its wall is a bit thicker, and there are standard rings available for it.

HTH.

Doug

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YORF member #11

Still, although some people have had great experiences on this motor, on EMRR, I calculated an approximately 30% failure rate of people who posted their flight experiences. This is an outrageously high value. Also, I want to fly "the big stuff". Although the 29 mm. kits are more expensive, it may pay off since I won't have to get the kits again if they crash beyond repair. Also, I am going to get the valuerocket starter set and it does its best stuff on a G (duh). Also, to get the tube fore HPR it is only $25 instead of a $90 complete casing. I'll also get the 29/60, and 29/100 tube too.

__________________
Always look on the bright side of life.

What goes up must come down (at least to the treetops)
Death awaits you all with big nasty pointy teeth. "

If you want the greatest variety of loads for a given case, get the 29/40-120.
Second only to that case is the 24-40.
I have had a 24-40 cases for oven 10 years and have had exactly ONE problem with it resulting in a faliure to deploy. That ONE failure was MY fault by getting grease on the delay element.
It is my staunch belief that most failures of the 24/40 are caused by USER ERROR as this is the most common case for beginners to RMS as this will fit in any Estes "D" mount.
I bought a large stash of 24mm reloads that are over 10 years old from a defunct hobby shop and those loads have had ZERO problems.
DO NOT FEAR the 24/40; I have found it to be my most versatile case and I have all of them through the 29/240. I fly the 24/40 more than anything as well.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, TURMOIL, FIASCOS, and HAVOC !