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Now that I am Level 1 Cert should I switch to reloadable motors instead of DMS?

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cerving

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Some of the 29mm DMS's aren't much more money than the reloads, and they ARE really easy to use. Then again, so are CTI reloads... you basically stick the reload in the case and screw on the closure. Easy peasy.
 

Off Grid Gecko

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In my opinion, to answer your question bluntly... NO. You SHOULDN'T do anything at all. I don't think anyone here or otherwise would tell you that you should switch. It's all up to you. There's no requirement for reloads. From what I've seen the cost "savings" may make some sense but not many dollars. At the end of the day, do what you like.
That's like asking "I just got my L1, should I go for my L2?" NO, not really. If you want to though, then do it! Launch it on an L if you like.
I blasted a Cesaroni 3G reload kit with my L1, but for the moment I'll probably be sticking to single-use for the near future while I get my DD stuff up to speed on smaller rockets. So I'm going the other direction, for the moment.
One saving grace on the hardware, if you are launching your L2 on a motor size that you plan on using a lot, it might pay to see if you can get a Cesaroni special with your motor purchase. You buy the reload and get the case free. Few vendors still do it, but Off We Go Rocketry honors the special.
There's still the HazMat fee, of course. I'm hoping to save a few C-notes and get several HP motors on my next shipment, as that will save far more than worrying about the price point of each reload. The smaller ones that can be shipped non-hazmat would be super cheap, I imagine, compared to the single-use motors, so in that range the money makes sense.
In the end, do what you like.
 

Arsenal78

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If high power is only once or twice a year, I'd stick with DMS unless there's a motor in particular you want. I stay far away from CTI (too many cato issues with their stuff). Loki motors are NOT hazmat from G through I impulse with the exception of the I110 moonburner and one other but that's it. The I405 is a ridiculous motor. Loki also has the lowest rate of catos between all high power manufacturers and their reloads aren't hard to build, just gotta clean the nozzle well after each firing.
 

Mikeyk

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Do you want to save money and enjoy assembling things? - RMS
Do you like spending more and want instant gratification? - DMS

:p :D
i would like to see someone respond to my post. I want to see my rocket fly without certification. Got 1 pro series 2 to almost 5000 feet. Light weight and a good design. I want to see what 4 launched simultaneously can do.
 

Mikeyk

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If high power is only once or twice a year, I'd stick with DMS unless there's a motor in particular you want. I stay far away from CTI (too many cato issues with their stuff). Loki motors are NOT hazmat from G through I impulse with the exception of the I110 moonburner and one other but that's it. The I405 is a ridiculous motor. Loki also has the lowest rate of catos between all high power manufacturers and their reloads aren't hard to build, just gotta clean the nozzle well after each firing.
Who doesn't like a Cato? I love spending time building my stuff to watch it blow up. Is part of the fun. Can you look at my question and give me a thought or two? Thanks
 

Mikeyk

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As
i would like to see someone respond to my post. I want to see my rocket fly without certification. Got 1 pro series 2 to almost 5000 feet. Light weight and a good design. I want to see what 4 launched simultaneously can do.
In 4 G pro series in the rocket. My question is, what are the chances of getting them all to ignite simultaneously?
 

Mikeyk

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Has anyone out there even tried this?
I have a good idea what what will happen if they don't all go at once. Landshark....cartwheel... skywriting. Is why I'm asking advice. I'll launch it anyway so that maybe I can answer the question if no one else can. And yes...I am crazy enough to do it just to find out. I live in the middle of nowhere. Nothing to lose, except 130$ of motors. Lol
 

PatD

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With the CTI motors and their pellet ignition system I would expect reasonably simo ignition. Test your initiators and match their impedance. Make your whip a bit long for variance in fire time. Probably the easiest brand to cluster.
Edit: And make sure your electrical lead lengths fairly well match.
 

OZRoc

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I have never had a problem. I have flown 54, 75 and 98mm motors.
I'm a big fan of CTI but I will have to admit here that I did have a K660 cato on me in 2015. Quite spectacular it was!
Situation was resolved with a replacement casing and a reload from CTI!

To resolve your question the answer is reloads from now on unless you intend to fly less than say 5 - 10 times a year (current C-19 restrictions exempted)
Cheers,
Mark
 

SecondRow

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i would like to see someone respond to my post. I want to see my rocket fly without certification. Got 1 pro series 2 to almost 5000 feet. Light weight and a good design. I want to see what 4 launched simultaneously can do.
As In 4 G pro series in the rocket. My question is, what are the chances of getting them all to ignite simultaneously?
4 G motors in one rocket, whether launched in a cluster or staged, is high power and requires certification.
 

Antares JS

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Who doesn't like a Cato? I love spending time building my stuff to watch it blow up. Is part of the fun. Can you look at my question and give me a thought or two? Thanks
I don't like Catos, and would wager most of the others here don't either. I would go as far as to say if you want to blow stuff up, this is not the hobby for you and you should quit rocketry and join a pyrotechnics guild.

On topic:

For high power, I fly Aerotech RMS exclusively. There are many more RMS reload choices than DMS motors, and I enjoy the process of assembling motors. Whether you switch to RMS or stick to DMS is entirely up to you and your preferences. There is no wrong answer.
 

neil_w

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I have a good idea what what will happen if they don't all go at once. Landshark....cartwheel... skywriting. Is why I'm asking advice. I'll launch it anyway so that maybe I can answer the question if no one else can. And yes...I am crazy enough to do it just to find out. I live in the middle of nowhere. Nothing to lose, except 130$ of motors. Lol
Perhaps a better idea than bombing this thread with your off-topic question would be to post it to a new thread in the appropriate forum.
 

Forever_Metal

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I've stayed with the single-use (AT), though i have reload hardware for both AT and CTI. A little more expensive (sometimes), but have had good luck with them.

It's still up to you though. Both are still decent options..

fm
 

heada

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Its really easy to bang out a spreadsheet to compare DMS to RMS to CTI to Loki assuming all things being equal. They never are equal and so you have to give weight to other items as well.

In 38mm and 54mm cost per flight, CTI break-even is nearly always first when comparing similar motors in the 6 to 10 flights range. RMS break-even is in the 8 to 22 flights range. Loki is 10 to 25 flights range. If you look at how much is costs per N-s per launch, CTI break even is 3 to 10 flights, RMS is 4 to 20 flights and Loki is 10 to 15 flights. (selected DMS H123W, RMS H100W, P38 H144W, Loki H144W; DMS J270W, RMS J350W, P38 J290W, Loki J528W; DMS J450DM (no white in that range), RMS J415W, P54 J760W and Loki J525W)

Most important thing is how easily you can get your motors. If you have an on-site vendor, support them and fly whatever they sell. If not, then you have to consider either shipping or doing a bulk buy at a regional launch and bring it home with you. Second is how often most rockets are unrecoverable at your sites. Talk to other flyers and see how often they lose cases. If its less than the break-even point, keep going with DMS but if losing a case is rare, it's better to invest in cases and go with reloadables because the long-term cost is lower and you have a much greater selection. Lastly, what other activities are you going to do with motors. If you want to stage or cluster, CTI is the absolute best with the pressed pellet in the top grain. If you want to get into research, the Loki snap rings are ideal. If all you want to do is 'whoosh....pop!" then you can't beat DMS for ease and quick turn around (but CTI is really close to those as well) If you want higher Length to Diameter ratio (the L to D I used showed up as a smiley) motors, no one can touch Loki, they have 38mm Ks and 54mm M motors. If you're in California, getting Loki motors involves jumping through some serious hoops so that may not even be an option.

Rocket science isn't just designing the rocket to be stable in flight, its also analyzing what motor to use and why. It's when to use electronics and which ones. There are lots of things in this hobby that involve work and research, motor vendor and type selection is just one and its different for every flyer.
 
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Mikeyk

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Its really easy to bang out a spreadsheet to compare DMS to RMS to CTI to Loki assuming all things being equal. They never are equal and so you have to give weight to other items as well.

In 38mm and 54mm cost per flight, CTI break-even is nearly always first when comparing similar motors in the 6 to 10 flights range. RMS break-even is in the 8 to 22 flights range. Loki is 10 to 25 flights range. If you look at how much is costs per N-s per launch, CTI break even is 3 to 10 flights, RMS is 4 to 20 flights and Loki is 10 to 15 flights. (selected DMS H123W, RMS H100W, P38 H144W, Loki H144W; DMS J270W, RMS J350W, P38 J290W, Loki J528W; DMS J450DM (no white in that range), RMS J415W, P54 J760W and Loki J525W)

Most important thing is how easily you can get your motors. If you have an on-site vendor, support them and fly whatever they sell. If not, then you have to consider either shipping or doing a bulk buy at a regional launch and bring it home with you. Second is how often most rockets are unrecoverable at your sites. Talk to other flyers and see how often they lose cases. If its less than the break-even point, keep going with DMS but if losing a case is rare, it's better to invest in cases and go with reloadables because the long-term cost is lower and you have a much greater selection. Lastly, what other activities are you going to do with motors. If you want to stage or cluster, CTI is the absolute best with the pressed pellet in the top grain. If you want to get into research, the Loki snap rings are ideal. If all you want to do is 'whoosh....pop!" then you can't beat DMS for ease and quick turn around (but CTI is really close to those as well) If you want higher Length to Diameter ratio (the L to D I used showed up as a smiley) motors, no one can touch Loki, they have 38mm Ks and 54mm M motors. If you're in California, getting Loki motors involves jumping through some serious hoops so that may not even be an option.

Rocket science isn't just designing the rocket to be stable in flight, its also analyzing what motor to use and why. It's when to use electronics and which ones. There are lots of things in this hobby that involve work and research, motor vendor and type selection is just one and its different for every flyer.
Great advice, I'll take it under advisement. I build my rockets at very low cost, with **** I usually find in a recycling bin. Build my find from beer coasters you get at a bar. Light weight and if you sandwich 2 together....they are just as strong as balsa wood,.....and free, with the purchase of a beer:). I can buy Estes G's. Going to cluster 4 on this big, heavy tube that was shipped to my workplace. Will be about 3lbs fully loaded. Shouldn't go that high if my math is accurate. I've never tried 4 motors at once. Hence my questions.
 

heada

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Great advice, I'll take it under advisement. I build my rockets at very low cost, with **** I usually find in a recycling bin. Build my find from beer coasters you get at a bar. Light weight and if you sandwich 2 together....they are just as strong as balsa wood,.....and free, with the purchase of a beer:). I can buy Estes G's. Going to cluster 4 on this big, heavy tube that was shipped to my workplace. Will be about 3lbs fully loaded. Shouldn't go that high if my math is accurate. I've never tried 4 motors at once. Hence my questions.
4 G motors (Estes rebranded Aerotech) is over the propellant weight limit for class 1(4.4 ounces) and so you'd have to fly as class 2 requiring an FAA waiver and HPR certification.
 

NateB

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I would go as far as to say if you want to blow stuff up, this is not the hobby for you and you should quit rocketry and join a pyrotechnics guild.
Yes and no. While a good CATO gets a fun reaction from your buddies ...


... most of us who enjoy pyrotechnics also prefer to see what we make function as intended rather than CATO. If I spend 40 or 50 hours on a complex shell, I'd be really disappointed if it was a flower pot, or worse left a crater in the ground.
 

bobbyg23

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In my opinion, to answer your question bluntly... NO. You SHOULDN'T do anything at all. I don't think anyone here or otherwise would tell you that you should switch. It's all up to you. There's no requirement for reloads. From what I've seen the cost "savings" may make some sense but not many dollars. At the end of the day, do what you like.
That's like asking "I just got my L1, should I go for my L2?" NO, not really. If you want to though, then do it! Launch it on an L if you like.
I blasted a Cesaroni 3G reload kit with my L1, but for the moment I'll probably be sticking to single-use for the near future while I get my DD stuff up to speed on smaller rockets. So I'm going the other direction, for the moment.
One saving grace on the hardware, if you are launching your L2 on a motor size that you plan on using a lot, it might pay to see if you can get a Cesaroni special with your motor purchase. You buy the reload and get the case free. Few vendors still do it, but Off We Go Rocketry honors the special.
There's still the HazMat fee, of course. I'm hoping to save a few C-notes and get several HP motors on my next shipment, as that will save far more than worrying about the price point of each reload. The smaller ones that can be shipped non-hazmat would be super cheap, I imagine, compared to the single-use motors, so in that range the money makes sense.
In the end, do what you like.
I used cti for my L1 and Gary from off-we-go-rocketry.com was a vendor at my launch so I got the free case and no shipping. Great deal and the cti reloads are stupid easy. Most people use cti at our club. I think I will go for my L2 and use 38mm reloads for that one.
 

Mike Haberer

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Nothing wrong with flying either RMS or DMS motors, and your decision should NOT be based on the L2 flight timing.

As you start planning ahead, you will figure out what are the most likely motors sizes and diameters that you will be building and flying (e.g.: 29mm G's & H's, or 38mm H's & I's, or 54mm J's & K's). Then collect the reload prices for both, and you will figure out that you will be financially better off buying a RMS case to go for the types of motors you will be flying more than 2-3 times.
Even then, you may prefer the simplicity, and lower risk of financial hit when flying out-of-sight-high with DMS motors, and there is nothing wrong with that.



There is something very wrong with these graphs - RMS vs. DMS cost break-even is usually around 2-3 flights, not 10-25 !
I agree. I took them at face value before but am working up my own graphs based on the motors in the graphs. Break-evens vary from 3 to 6 flights. I'll post if I ever get them finished....
 

Walter Longburn

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The DMS H550 costs $1 more than the RMS H550. So if you want to save money with the RMS H550 your going to have to fly a lot of them.
 

Buckeye

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There is something very wrong with these graphs - RMS vs. DMS cost break-even is usually around 2-3 flights, not 10-25 !
Break-evens vary from 3 to 6 flights.
Please show your math and tell us where you shop for AT reloads and AT hardware. We would love to know where you get these screaming deals.

A number of us in this thread already disproved your assertions of "2-3" flights to break even.
 

afadeev

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Please show your math and tell us where you shop for AT reloads and AT hardware. We would love to know where you get these screaming deals.

A number of us in this thread already disproved your assertions of "2-3" flights to break even.

I have an XLS of all rocket motors and reloads I've bought, or considered buying, over the years.
I place the bulk of my reload orders annually, during BF / holiday sales.
If anyone wants a copy, PM me.
 

Buckeye

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Retail price is the only fair comparison. AT Hardware, RMS, and DMS all go on sale at various times, at various rates, from various vendors.

Here are the updated calculations to the chart above. Retail prices taken from Balsa Machining website.

Capture.PNG
 

mo2872

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I'm with Theory.........reloads because it adds another dimension.

Plus, who doesn't like having more hobby stuff.....errr.....equipment!
 

Alan15578

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A fellow forum member JLebow worked out this graph.

View attachment 427251
I would never get that many flights in before casing loss. It is also an issue with MR, and not just contest rockets. For the record, I lost two Camrocs and only got one picture to show for it. I bought 3-4 Cinerocs and I only have the last one, another rocketeer has the only film that I recovered, from a recovery in the Mississippi River (an old story told too often). In theory, rockets are recoverable, in practice, not so much, and the motor casings are along for the ride. YMMV
 
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