Reloadable Motor System

[Steve Shannon]

Correct me please if I'm wrong, but can't you then easily also make your own snap ring cases and graphite nozzles? I do own a lathe and have regular access to mills,surface grinders, cnc stuff, etc. Being both NAR and TRA L2 I should know this but have yet to delve into that rabbit hole...

Your self manufactured cases and case parts may be used at Tripoli Research Launches but not at launches limited to certified motors.

 

[Wallace]

Thanks Steve for clearing that up. I was 99 percent certain, am now 100. Not complaining about hardware pricing in any way other than I personally have a hard time coming up with the dough to buy it. I fully realize what goes into sourcing usable tubing, machining it to spec and anodizing. Not being anything other than a hobby level machinist for most of my life does not mean I'm not well versed in the area. I have several friends that either own shops or work for others so I get to hear it all. That doesn't even include the cert process so realistically it's a deal. I do support vendors as much as possible and would never knock 'em unless they're blatantly gouging. But...If I can "find" quality tube, cut a few snap ring grooves in it, then either make or buy re-usable graphite nozzles then it becomes somewhat more attainable. Simply a trade off between time and money.

 

[jqavins]

Resale value is irrelevent unless you plan to resell. If you plan to use cases until you die or they do then there's no point in even bringing it up.

 

[Wallace]

Tough point to argue in that sense, Everything and everyone dies eventually. Do you have family? They may care, How far you care to take a non argument is entirely up to you.

 

[gldknght]

No one in their correct frame of mind truly enjoys cleaning cases. But if you look at it from the other perspective, even if your used "stuff" sells for asking price you're still out that 5% plus what, if any you spent on shipping. I did preface my original with the fact that I do actually love reloadables, just bothers me that "I" personally cannot justify(or usually) afford them..

I must not be in my right mind. I actually enjoy cleaning my cases, just as I enjoy cleaning my rifles after a shoot, part of the hobby.
I just soak my cases in the hottest (Dawn) soapy water and scrub them with a small stiff vegetable brush, usually takes me less than 5 minutes per case.

But more on topic, I've never actually purchased a single use motor other than Estes Bp. It has always been way cheaper in the long run to use the rms setups. In my 25+ years of flying mid and high power, I've only lost one reloadable case when my rocket was eaten by the rocket guds. The rocket went up and no one saw it come down.

 

[jbr]

I only lost one AT casing, friend borrowed my J350 case and rocket was never found
I almost lost one myself, it came loose from the rocket and I said I have the rocket, a friend said I have the casing, we found both in 3 foot tall wheat

 

[crossfire]

Wallace, I agree with you on some points regarding the economics of RMS vs SU. What I don't see mentioned is the convenience and ease of SU motors: no assembly and no residue cleanup. Prep it, fly it, chuck it.
On the other hand some of us actually enjoy assembling and cleanup of our casings and motors.....
OK nobody enjoys cleaning up. But some enjoy assembling.
And this will be a necessary skill when moving up to the larger motors.
Whether or not SU or RMS is more economical depends on your personal situation, as previously detailed.
Also, consider this: if the resale value of used casings is 95% of retail, what is the real cost to you?
You cannot resell a used SU motor.

Unless it's a hard to get motor case your lucky to get 40% of retail cost for a used case.

 

[Wallace]

You guy's are lucky, and or weird...I'm jealous

 

[prfesser]

Thank you, JLebow and jbr, for providing actual numbers; I wouldn't have guessed that the payoff for reloadables took that long. In my case (no pun intended) payoff never occurs, as I lose motor cases far too often.

jbr, those 29 mm cases are shameful! They are supposed to be polished. Send them to me, I promise to return them. Eventually.

Wallace, do NOT go down the rabbit hole of Research. As my good friend Jim Mitchell (old farts will remember Thunderflame classes, and Jim's 'Yellow Jacket' propellant), it's a bug that bites deep and doesn't let go.

Best -- Terry

 

[Wallace]

Thank you, JLebow and jbr, for providing actual numbers; I wouldn't have guessed that the payoff for reloadables took that long. In my case (no pun intended) payoff never occurs, as I lose motor cases far too often.

jbr, those 29 mm cases are shameful! They are supposed to be polished. Send them to me, I promise to return them. Eventually.

Wallace, do NOT go down the rabbit hole of Research. As my good friend Jim Mitchell (old farts will remember Thunderflame classes, and Jim's 'Yellow Jacket' propellant), it's a bug that bites deep and doesn't let go.

Best -- Terry

Thanks for talking me down off that ledge. I've been pondering it for quite a while, while fully aware that If I live to be somewhere around 220ish? I "may" be able to complete some of the things I'm currently obsessed with.

 

[Wallace]

And you may want to check the Yard Sale section occasionally before selling any of your "stuff". Not at all uncommon to see asking prices (not saying that's what they actually sell for) for used parts in excess of new. Ok, not new as in retail pricing, but new as in internet prices from some of our well known and loved vendors..

 

[jbr]

Thank you, JLebow and jbr, for providing actual numbers; I wouldn't have guessed that the payoff for reloadables took that long. In my case (no pun intended) payoff never occurs, as I lose motor cases far too often.

jbr, those 29 mm cases are shameful! They are supposed to be polished. Send them to me, I promise to return them. Eventually.

Wallace, do NOT go down the rabbit hole of Research. As my good friend Jim Mitchell (old farts will remember Thunderflame classes, and Jim's 'Yellow Jacket' propellant), it's a bug that bites deep and doesn't let go.

Best -- Terry

after making so many casings, I just get lazy

 

[Wallace]

Would probably be very viable to make a tool for cutting snap ring grooves for making your own custom cases, similar to what is used for o-ringing engine blocks. Simply rides in the bore and with the correct carbide insert, requires nothing more than a hand crank...

 

[jbr]

I hand ground on a grinder all the groove tools needed

an example of the 38mm tools, internal and external

 

[Wallace]

Well done, I often find my tools making more/different tools,. My thought is that once you make a "hand" tool you no longer need a lathe/mill or even power source. You could theoretically make cases in the field...Or borrow it to friends. For research/Ex only of course. Thinking this may be pushing forum limits even though it's currently a discussion about tools?

 

[jbr]

I doubt a hand tool would give the precision needed to make accurate grooves for snap rings with the right width and depth
6061 is harder to cut than you think

 

[Wallace]

I respect your answer and at the same time disagree. Try cutting grooves in a compacted graphite diesel block. With the proper tooling it's not that difficult. Granted aluminum is a world apart...

 

[Wallace]

You've inspired me to "think" more about making said. Thank you Sir.

 

[Wallace]

Years ago I ordered a custom set of ductile iron jugs for a race bike that had huge bores, therefore never ending head gasket sealing problems. They arrived with an O-ring groove and 1/16"? viton o-rings in lieu of head gaskets. They were cut absolutely perfectly, just barely missing everything vital. I immediately called the manufacturer to ask wtf? He explained that they were done with a hand held cutter of their design and regularly survived on top fuel engines. Turned out he was correct. After dozens of head gasket failures prior, never had to worry again. As a bonus they were actually re-usable..Pretty far off base from our discussion but just an example..

 

[jbr]

ok, had to google some stuff, much better craftsman than me to do that hand held
https://www.competitiveproduction.com/articles/why-compacted-graphite-iron/

my lathe is manual is about as close as I get to hand tools

some woodworkers cut mortise and tenon, and also finger joints by hand, I prefer cnc router with hand cleanup afterwards (router does round corners unless you do dog bones)

 

[Nytrunner]

Thinking this may be pushing forum limits even though it's currently a discussion about tools?

This is just machinist shop talk. Nothing restricted yet

 

[tim cubbedge]

Exactly. Until you start talking about formulas, nothing restrictive here.

 

[Wallace]

All is good then. Thanks for the interesting conversation. In my mind that's what truly makes forums great.

 

[Wallace]

" The nodularity and tensile strength of the material also increases as wall-section decreases" . That's a quote, but certainly not mine. Even tough not allowed for our purposes it is a rather Impressive material eh?

 

[yorn]

The graphs of the break even point for different motors are helpful, but there was an additional consideration with the break even point for me. I bought an Aerotech 29/180 case for my L1 certification flight. The reason I did it is simple.

1) I want to gain experience with reloadable motors.
2) I can only order one H impulse motor for my L1 certification flight. The 29mm DMS type motors require me to pay a Hazmat fee of $35. If I ever fly another disposable 29mm High Power motor, I will again have to pay the $35 Hazmat fee, which brings me up to $70 in Hazmat fees. I figured I could just invest that $70 into a case and gain some experience with reloadable motors instead of throwing it away on Hazmat fees. Sure, I paid more than $70 for the case and closures, but it wasn't that much more, and I think it is worth it for the experience I can gain. Hopefully I can hang onto the case for a while. I could also use 29/120 and 29/100 G impulse motors in the 29/180 case with the Aerotech RAS.

 

[Wallace]

I agree, reloads are cool. I "think" I have 7 or 8 cases/closures/seal discs, etc. and they are great but if there's an su. alternative for 2 bucks more I'll go that way every time. It takes alot of stress out of the flight since I don't have to worry about damage or loss. I totally get your point about the Haz shipping, absolutely cannot bring myself to pay more for shipping than for the item itself. Haz Mat has never been a problem for me because we have our friend Wildman on site at every launch and if he can't make it Jackie's usually happy to bring whatever you call ahead for. That kinda thing really makes you appreciate vendors..

 

[readytorock556]

What rms is everybody using now? I have been away from the hobby for quite awhile and I'm trying to get caught up on things now.

I was out for a while also, haven’t launched in 7 years. I would definitely go with reloads! I use 18, 24 and 29mm reloads. Just launched motors that were over 8 years old and they all lit fine and way cheaper than single use with exception of the 18mm but they are awesome in Estes rockets! I only buy singles if I can get them on sale. Welcome back to the hobby!

 

[Wallace]

Aye..

 

[ascastil]

I have AT casings in 24 to 38mm. I use them because I enjoy putting together the motor.

 

[jd2cylman]

I have AT casings in 24 to 38mm. I use them because I enjoy putting together the motor.

Yep. I believe I have every AT compatible case from 18mm to 98mm so far... Unless AT finally releases the 75/10240 and the 98/25600...