Single use vs. reloadable

Ever since I got into mid power I have always used single use and recently LMS motors. I was thinking about buying an AT RMS system 29/120 or 38/120 but I would like some feedback before I do. The thing that has always kept me from buying one so far was their weight and cost. I want to know if anyone feels that the added weight takes away from their performance. Also, could someone speak to maintance issues/costs with such a system (forward and rear closures, o-rings etc.) do you really save money and keep the performance or is it just more flexable a system for delays etc. and the cool factor? Last but not least if you could recommend one system for L1 and L2 cert what would it be?
thanks
jer
ps. I tried the new G80 motor yesterday and really liked it!

I have attached a picture to show why it may be time to buy a RMS!
Sometimes I buy motors before I check my wallet!
jer

Jeremy:
I don't use any! SU Motors I Like the RMS MUCH! better, It WILL! be Cheaper in the Long run as the loads are cheaper but you do have to buy the Motor 1st so it will take a while to start the savings, By "Motor" I mean The Case forward & aft closures and in your care a Seal Disc as well, As for power Most Re-loads are more powerful than their SU counter parts Not To Mention once you go past an H you have like 1 maybe! 2 SU H, I & J's to choose from. For a LV1 & 2! you can go with the AT 38/720 Motor as you can use the I600R for Lv1 and a J350W, J500G or J420R for LV2. The 38mm Fwd & aft Closure's will fit ALL the 38mm Cases so you only need the one set to start, But take my word on it you WILL!!!! Buy more cases For cleaning It take 5 Minutes I use Distilled White Vinegar Its Cheap and works Great! and has NO! adverse affects to the Aluminum. Hope this Helps. -G-

I'd go straight ahead with RMS. The pro's are that:
- it's cheaper, it'll save you big bucks if you're a heavy MPR flier.
- it has more choices of reloads and it gives a larger variety (only if you fly the 29/40-120 - the Easy Access stuff doesn't have many choices per case).
- it can be enjoyable to build the motor and clean the case.


The con's are that:
- it has a high base price.
- it is expensive to lose a case - something that can be easily done.
- more complicated.

Those are some of the basic qualities of RMS.

No Question about it. Get a 24mm and a 29 Hobby line reload cases and your choice of motors will be excellent and you will save major bucks. It doesn't take long to pay for the cases. I'm really looking forward to the G76G when becomes available.

Many of us have the same problem. My cover story is that I like to be well prepared. There are others on this forum who have collections of 300+ motors.

I think the best value in reloadables is the Aerotech 29mm RMS 40-120 system. The E, F and G reloads can be had for 7-10$ each at JoePilot.com or Hobbylinc.com. The engine case is expensive, but will pay for itself after 10-12 launches. I don't use them if the rocket will pop the chute at 2000+ ft, and always use positive engine retention.

I bought 4 of these cases last year and have burned 40+ reloads in them. With luck I will get years of use from them.

I recommend you go for one cert and one engine at a time. Got my L1 last year using a Cesaroni Pro 2 grain 38mm engine system. Cesaronis are the easiest to use by far and very reliable, at a very slight price premium.

This year I will be going for my L2 using the Cesaroni Pro 2 grain 54mm engine. Bigger rocket with dual deployment.

Having certs is great, having fun, learning new techniques and building experience is even better.

Good Luck.

RMS is much better. You don't have to rely on a plastic casing to hold together and you can Quality control the parts. I have in the past called Aerotech to replace grains that were defective. With a Single use, you will only find out when you ignite the motor.

RMS is the only way to go. It is a PITA to reload ( takes more time away from flying). The best part is the great selection of reloads and delays.I would guess 3-4 flights to break even. I still love to buy HP single use motors when I can. Getting harder and harder to find.

Just looking at that pile of motors, you could sell just 3-4 of them at your next launch and have 45-55 dollars needed to buy a 29mm 120 hobby case. Cost to get in 00.00

You will find that one case will let you choose from e, f and g re-loads, ranging in price from. 7.00 -12.00 a flight. That's white lightning, blue thunder, smokies, redline and just introduced mojave green. Very versatile case me thinks! You will be able to loft anything up to approximately 3.5lbs depending on diam. much more economical than single use. And in your case, where it looks like you fly quite a bit, a definite plus and savings.

Ok I'm ready to buy. But first, what is the difference between the 29/40-120 and the 29/120? Can the former take G71 reloads or just the later? What one is more flexible? Also, who is better a Rouse tech or Dr. Rocket?
Last thing on ebay right now I can get a 3 set kit for $149 kit but I don't know if it is the 29-120 or 29/40-120 or what the big difference is.
thanks
jer

The 29 40/120 is a Hobby Line case and can take many, many reloads. Very versatile, it can use reloads with every propellant Aerotech offers except for Warp 9. The 29/120 is an Easy Access case and can take only two or three reloads, although you can still buy more cases, without closures, for 15-30 bucks depending one which one you buy.

Can the 29/40-120 use G power reloads and E, F stuff? How does this work is there a space or something you use when when switching between F and G reloads?

Looking at Aerotech's web site I see the "High Power Style" reload section where they mention the 29/120 and 38/120 casses. However, the only difference I see ifrom the hobby line is that these reloads come with s,m,l delays? Also, acording to their site the 38/120 with the G69P does not require a LEUP or cert to buy or use. Is this true. It does not really matter because the G69P with its 137n/s seems the same as the new G80 anyway in terms of max thrust. I am guessing the G69 may burn longer though.

I hope that I am not stearing you in the wrong direction but here is a site that sells the hobby line of motors for the reloads.
https://www.a2zhobbies.com/Aerotech/RMS_Motor_Reloads
every thing listed as a 29mm reload is for the 29/40-120 case, from E-G.
when loading a E reload in the 29/40-120 case there will be a space with out any grain in it because it is a single grain eliment and when using a G reload it is a 2 grain unit so the case is full. These reloads are able to be shiped with out hasmat and no LEUP. As far as the 38/120 case there is a few reloads for it the G67 is a good motor and then you have the G339 which is a warp 9 motor that needs another sorce for the ejection charge because it does not have one.
Myself I am getting into the hobbyline of reloads by getting 4 of the 29/40-120 cases and clustering them together and also using them singualy also.
I have a few rockets that are built to take the 29mm motors. I also have 4 rockets that are built for the 38mm ones also thoses are mostly 3" dia and one 4" dia rocket, and one 2.1" dia rocket.
I did my L1 on a 3" dia rocket using the Cesroni pro38 2 grain on a H motor, I have the 1 grain case and a 5 grain case for the J motor and I am going to put a adapter tube in it to be able to use a I motor also which is a 4 grain motor.
I did my L2 with a AT J350 in the 38/750 case and also got the 120 case for the one grain motors as well so I can use it in my 2.1 amd 3" rockets.

The AT- 40, through 120 indivual cases will only take the reload that is for that case where the hobby line 29/40-120 will take all the reloads that is made for that case.
As far as a motor that is good for all around use I would go with the 29/40-120 hobby line motor for MPR and in the 38 size well that is to ones prefreance on what you want to use. I dont think there is much diferance between Rouse tech and Dr. rocket just differnt color and price.
Just rember that larger reloads will require hasmat to ship and a LEUP to buy and store unless you have the convieance of haveing some one in the club that has a LEUP or a vender that frequents your launches which my club has neither :cry:

I hope this helps.

Jeremy Lundy said:

Looking at Aerotech's web site I see the "High Power Style" reload section where they mention the 29/120 and 38/120 casses. However, the only difference I see ifrom the hobby line is that these reloads come with s,m,l delays? Also, acording to their site the 38/120 with the G69P does not require a LEUP or cert to buy or use. Is this true. It does not really matter because the G69P with its 137n/s seems the same as the new G80 anyway in terms of max thrust. I am guessing the G69 may burn longer though.

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high power casing is slightly different from the hobby casing so the reloads must be used with the correct casing of they will not fit and the o-rings will not seal. That is "bad" since it will destroy the casing or end closures as it fails in a flaming death.

Used correctly they are great. The fantastic instructions on the Aerotech website show you with words and pictures how they are loaded and you can see that the hobby line motors with lower total impulse simply have spacers to fill the empty space.

See the very first sticky thread in the top forum for the simple document that explains about Model Rocket vs. High Power Rocket motors. That will clarify your question about that.

Best advice I can give as a long time MPR flyer, somewhat new L1 flyer - get the 29/40-120 casing. E-G power under $15 per load, carries the G71R and the just announced (but yet to be certed, I believe) G76 green.

Beyond that - if you're looking for L1/L2 capability, go to 38mm RMS. The 33/240 gets you some nice H loads, and the 360, 480, and 600 cases carry some amazing I loads. The 720 casing gets you into L2 territory with the J350W and the J420R. The best part about RMS cases like these is that you really only need one set of closures, as the closures are compatible across all cases of that diameter, including the 38/120 (which I also love). Buy the full 38/240 motor, then just by the rest of the cases and you're set (although, above the 480 casing, you'll also need a seal disc, but that's just one more thing). This is not true of 29/40-120...those closures are unique to that case, but all the HPR style RMS casings are compatible closures in the same diameter.

I fly alot of 29mm HPR motors in my 29/180 and 240 cases. These include the H165R and H180W loads. The H180 is just an absolutely rippin' motor for it's size - the pic I attached is an H180 in my LOC Norad Pro Maxx. The closures from these cases can also be used on my 29/120 (but NOT the 29/40-120). Once you buy the first motor with the closures, buying the rest of the cases is fairly cheap in the 29mm size, so have fun!

One other point about the 38mm. If you buy the smaller motors then move up above about the 480 case you need the end closuse with the biggeer hole. Or do they all come with the bigger opening closure now?

pyrovette20 said:

One other point about the 38mm. If you buy the smaller motors then move up above about the 480 case you need the end closuse with the biggeer hole. Or do they all come with the bigger opening closure now?

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I believe they all come with the bigger opening closure now.

Personally I would like RMS, but in Bulgaria there are no RMSs, so I use single use

P.S. Is there a way to scratchbuild an RMS from a single-use motor and other materials?

In my opinion a CTI motor is a safer bet for cert flights. Then once you are certified you can fly aerotech if you want, the reloads for AT's are much cheaper but you cant beat the CTI motors for ease of use and reliability. Just my $.02.

something nobody every points out about differences.

the hobbyline case (29/40-120) uses "c-slot" core grains. these tend to burn longer at lower thrust.

the 29/120 "high power" style case reloads use "bates" grains, these tend to produce more thrust, but shorter burn times.

my suggestion, buy them both, even though there is only 2 (so far) reloads for the high power case, its worth having. I personally have 2 of each.

I came across this thread via a Google search. I too am looking at the RMS cases and wonder why I would need one. I am all for saving money but when I can get the Aerotech Economax and Econojet single use motors why bother with a RMS case other than variety of motors offered?

Rocket2Russia said:

I too am looking at the RMS cases and wonder why I would need one. I am all for saving money but when I can get the Aerotech Economax and Econojet single use motors why bother with a RMS case other than variety of motors offered?

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As far as I can tell, unless you're launching A LOT, which amortizes the cost, then additional variety is really the only reason.

Rocket2Russia said:

I came across this thread via a Google search. I too am looking at the RMS cases and wonder why I would need one. I am all for saving money but when I can get the Aerotech Economax and Econojet single use motors why bother with a RMS case other than variety of motors offered?

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Honestly I would stick to SU motors now in 29 and probably 38 with all the DMS variety. the savings per load on reloads arn't that great. If you plan on launching a dozen HP 29-38's a year thats when I would start looking into reloads. also 54mm and above there are WAY more options in reloads and you make back your initial costs quicker.

Kallahan11 said:

Honestly I would stick to SU motors now in 29 and probably 38 with all the DMS variety. the savings per load on reloads arn't that great. If you plan on launching a dozen HP 29-38's a year thats when I would start looking into reloads. also 54mm and above there are WAY more options in reloads and you make back your initial costs quicker.

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Actually the 29 mm Hobbyline case is the best deal of any. You can start saving after only 4 uses because the G (and E, haha) non-HP reloads are non-Hazmat, if you compare discount order to buying onsite that works out to the 4 I think, or even better compared to the actual Haz fee. The 24 mm is rather fiddly though and takes longer to come out ahead. The other great deal in cases incl. 29 mm is the CTI certification specials, if still avail. and you're certifying don't miss it.

Another great thing is if you need non-standard delay times or ejection charges, it makes it all adjustable and availability less a problem, though DMS gets most of that too.

bill_s said:

Actually the 29 mm Hobbyline case is the best deal of any. You can start saving after only 4 uses because the G (and E, haha) non-HP reloads are non-Hazmat, if you compare discount order to buying onsite that works out to the 4 I think, or even better compared to the actual Haz fee. The 24 mm is rather fiddly though and takes longer to come out ahead. The other great deal in cases incl. 29 mm is the CTI certification specials, if still avail. and you're certifying don't miss it.

Another great thing is if you need non-standard delay times or ejection charges, it makes it all adjustable and availability less a problem, though DMS gets most of that too.

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+1, the 29/40-120 is super awesome. You can practice the whole midpower range and work on your reload skills w/ no special tooling required.

I should have quantified my response by adding that it's my opinion for LPR.

Versatility, and where do you want to go from here? If you are happy launching the same three rockets with the same three SU motors, and you can cover the cost, why change?

But if you plan to expand into high power and build more versatile rockets, you will need a variety of motors. More thrust for windy days, more impulse for higher waivers, more thrust and more impulse for that Mach attempt.

Besides that, I think most people start to get bored doing the same thing over and over again, and like new challenges. Building motors is fun once you get used to it. And then it start to open up avenues into research motors, etc.

I have one word of advice, however. Since you are in DC, if you ever think you might join MDRA and go high power, then consider CTI instead of AT. Our field vendor exclusively sells CTI motors, and you can buy them on-site with no shipping and no HAZMAT fees.

John - Is CTI producing 29mm motors yet? I bought a Pro29 case last summer before realizing the predicament they were in and haven't been able to use it because I'm limited to less than L1 G motors.