LMS Vs. Econojet

Is there really any advantage of one over the other? Aside from a couple of motor choices where the LMS does not require a hazmat fee, the LMS beats the Econojet price by about $3 for the same motor. I checked Thrust curve to see if they differentiated between the two and it appears as though they treat them the same. I am leaning toward the LMS simply because it seems to be a gateway into RMS motors and I can save a few bucks.

The LMS motors you assemble yourself compared to the Econojets which come already assembled.

The LMS assembly is not hard. The only thing you need is some 5 minute epoxy for gluing in the forward bulkhead. Once the motor has been fired, you just throw it in the trash just like any other SU motor.

If you do go with LMS be SURE to let the epoxy cure for 24hrs before flight.
Even if you use 5 minute.
Epoxy MUST be cured to handle pressure.

Go LMS. Same exact motors as the EconoJets, you're just proving the assembly labor, thus saving you that cost and gaining experience.

With LMS you have more options too. They aren't only limited to the low total impulse EconoJet F's, they also offer a few beefy Gs!

And yes, assembly is comparable to an RMS. Once you do an LMS those will come easy.

blackjack2564 said:

If you do go with LMS be SURE to let the epoxy cure for 24hrs before flight.
Even if you use 5 minute.
Epoxy MUST be cured to handle pressure.

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I remember when the LMS motors were first announced, they said the motor could be flown as soon as the epoxy solidifies but I would definitely wait much longer than that. 24 hours is definitely a safe bet.

The only thing that might concern me is what might happen if the epoxy failed to set up properly either due to a non-through mix or improper mix ratio.

In other words, if you are buying on site to fly that day, go with the standard. If you are buying to fly at a later date, or having them shipped, go with the LMS, save a few bucks plus hazmat fees.

The answer is that both are wrong answers. Just kidding.

Seriously, I wrestled with the same choice as you very recently. Just go RMS. It is much cheaper in the long run. I regret every SU and LMS motor I purchased F and up.

Not sure if the price points changed, but the Economax were a great deal when they first came out. The older E20 2-packs are nice, the Newer F44 2-packs are too. Check if the G74 2-pack require hazmat (or buy from a local vendor).

I think the LMS F20, F23, F27 and F42 became unnecessary with regulation changes.... To my knowledge the econojet will ship hazmat free.

The LMS only makes sense now in the G series of motors. (G77, G78, G79, Etc)

IIRC, the LMS was released so users could assemble the motors themselves and save a few bucks. The only issue I see might be how a warranty claim would be dealt with should a CATO occur. Usually when a RMS motor CATO's, user error is the first thing that comes to mind.

Of course with the G motors, going the LMS route waives the HAZMAT fee.

Both versions of the EconoJet's, either already built and 'ready to go' or LMS's which require assembly, are identical in terms of performance and they both ship without a HAZMAT fee via USPS if desired. The pricing differential is due to labor and a tiny quantity of material (epoxy). So, you can save a few bucks if you go the LMS route but as others have said, they require a small amount of assembly and epoxy setup. They are very easy to assemble but if you don't want to worry about it then just buy the 'ready to go' versions for a few bucks more and you're good to go.

Where LMS really shines is in the G impulse range - they are single use and can ship HAZMAT free via USPS if desired. Their 'ready to fly' counterparts must ship HAZMAT; no exceptions.

The relatively new EconoMax 24mm F44's are a great value and can ship HAZMAT free via USPS if desired. Their bigger brother, the G74's must ship HAZMAT; no exceptions. These are both awesome motors by the way and at great price points.

The F20 sucks in either form! None of the rockets in my 29mm fleet have a good flight with that motor, so I no longer consider it.

I wasn't aware of the adhesive requirement, good to know for planning!

Thanks for the confirmation everyone. Yes, a reload case is in the future but not in the cards right now due to funds and my available launch site. I have a local field that is just big enough to launch our new Argent dut I am going to have to keep it to no more than 1k. Even then, I just barely have minimum room and the winds have to agree with the long axis somewhat. With that in mind, I'm an nine on SU until we have a more suitable site to launch from.

The other nice thing about the LMS motors is that their delay grains are the same as the RMS motors, so you can drill them with the delay tool. Nice option when the available "stock" delay isn't quite right for your rocket.

Oberon said:

The other nice thing about the LMS motors is that their delay grains are the same as the RMS motors, so you can drill them with the delay tool. Nice option when the available "stock" delay isn't quite right for your rocket.

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Yes, great point.

WLViking said:

The answer is that both are wrong answers. Just kidding.

Seriously, I wrestled with the same choice as you very recently. Just go RMS. It is much cheaper in the long run. I regret every SU and LMS motor I purchased F and up.

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At some point I feel the curve shifts. For example the M1350 is awesome, and I am not about to fly enough M motors per year to justify another $350 on hardware. Heck the reload version is only $80 less than the single use, and you cut out all worries about losing or breaking the hardware. I have to imagine this holds true for the bigger 54mm motors as well.

Buckeye said:

The F20 sucks in either form! None of the rockets in my 29mm fleet have a good flight with that motor, so I no longer consider it.

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I used to fly my Leviathan on it at LPR launches with a 1,000 foot ceiling, and it worked great. Any 29mm rocket lighter than a Leviathan should do just fine.

Screaminhelo said:

I wasn't aware of the adhesive requirement, good to know for planning!

Thanks for the confirmation everyone. Yes, a reload case is in the future but not in the cards right now due to funds and my available launch site. I have a local field that is just big enough to launch our new Argent dut I am going to have to keep it to no more than 1k. Even then, I just barely have minimum room and the winds have to agree with the long axis somewhat. With that in mind, I'm an nine on SU until we have a more suitable site to launch from.

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I used the Econojet motors to fly my Leviathan on our club's low power field, which has a 1,000 foot ceiling. I used the 4-second delays, and it was great. You might want to do some sims first or at a least compare the weight of an Argent vs Leviathan to see if they would work for you, but I'm pretty sure they will. I was attracted by ease of use, variety of propellants, low cost, and no need for hazmat shipping.

Buckeye said:

The F20 sucks in either form! None of the rockets in my 29mm fleet have a good flight with that motor, so I no longer consider it.

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My Fat Boy flew a treat on these motors!

A little plug for RMS.... I just bought an AT 29/40-120 casing on eBay for $45.34 shipped. I also got 10 G76-7G reloads from Wildman at a total of $118.40 shipped. That's a total of $163.74 for ten motors, which comes to $16.38 per motor. The closest SU motor is $18.19 before shipping. And after I buy ten more reloads next year, I'll be at $14.11 per motor shipped. And down it goes from there....

A case is in my future, just not right now. Until I can be sure that I have a launch site that has a little more room, reloads could become very expensive. I am going to check out a spot this weekend that may be just big enough for 1k flights, then I have to get permission to launch from the owner. Until then, I figure that I'll just play it safe.

Screaminhelo said:

A case is in my future, just not right now. Until I can be sure that I have a launch site that has a little more room, reloads could become very expensive. I am going to check out a spot this weekend that may be just big enough for 1k flights, then I have to get permission to launch from the owner. Until then, I figure that I'll just play it safe.

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Sorry, I'm not following you. What do launch site dimensions have to do with whether you use SU or RMS? Total impulse is total impulse....

The RELOADS do not become more expensive since they remain the same price, but the MOTOR becomes more expensive if you lose the MOTOR CASING (with end closures) because you launched a Reloadable Motor System in a rocket that got lost because it was flown on a field that was too small. Perhaps I should have said "flown "off" a field...."??

Bat-mite said:

Sorry, I'm not following you. What do launch site dimensions have to do with whether you use SU or RMS? Total impulse is total impulse....

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Smaller site=easier to loose the rocket and attached components. This is my first foray into MPR. Our regular launch site works well for LPR but I try to keep launches somewhere around 500 feet due to some limitations of the field. Since the site that I am looking into may only have one axis that is actually big enough, I choose to hedge my bets and learn the ropes without risking a $50 case. I see the math and agree with it, RMS is cheaper to fly in the long run but my choice is to eat the additional cost and do a few launches with SU motors first to get my feet wet.

Sounds like a Jolly Logic Chute Release might be in your future as well!:wink: If your flights are limited to between 500-1k altitude, and, you want to move up to mid power, you should be considering rockets with high drag. Something along the lines of saucers, and, short, fat rockets, like the AT Sumo, or even the G Force, all low altitude performers on G motors.

I'll find a better MPR site before too long but I do like the idea of the Chute Release. With one of those, I could fly any number of pastures very close to the house. The Argent purchase wasn't thought out too well but I had to get one at that price, then I made it a Christmas gift to my boy. We'll fly it within our limitations for a bit but I do hope to get to a local club launch in April and send it to 1k plus.

One other thing to consider is not just the size of the field, but also what surrounds the field or is actually on the field. There's the risk of a rocket drifting out of the field, but also a risk of a rocket crashing outside the field or coming down ballistic on the field. It's one thing if an Estes LPR weighing a couple ounces drifts away on the wind. It's another thing altogether if an Argent weighing a full pound lawn darts into a neighborhood, or on the head of a soccer player. I could probably pick a motor that would keep my Mega Der Red Max within my local schoolyard playground, assuming a nominal flight, but I'd still never fly it there for fear of what would happen if it were to crash --- too many houses, cars and people nearby.

The field is an unused pasture. I was able to drive by and check it out today. There are a couple of houses in the area but far enough away and sited so that they can be avoided pretty easily. It looks a lot better in person than it does in satellite view, there were some shadows that made it look much smaller. I think that it is still a good field for a weather bird though. Now I just have to give them a call and see what happens.

I am in a somewhat rural area so getting clear of people is easy but wide open space is a little tougher.