REALLY need help understanding AeroTech nomenclature...

[noffie79]

The floating forward closure is with the adapter system. Since the reload that you build is shorter than the case it's in, the floating forward closure is needed for the ejection charge, if there is one.

 

[CzTeacherMan]

The floating forward closure is with the adapter system. Since the reload that you build is shorter than the case it's in, the floating forward closure is needed for the ejection charge, if there is one.

Yeah, basically it's AT version of the CTI spacers. Also known as the RAS... Basically the only reason I started buying AT HPR Hardware

 

[noffie79]

Yeah, basically it's AT version of the CTI spacers. Also known as the RAS... Basically the only reason I started buying AT HPR Hardware

I'm right there with ya

 

[soopirV]

I'm going to try to put my biology training to good use and try come up with a phylogenetic tree showing the family...maybe seeing it graphically will help those of us who want to join but are wary...stay tuned! Maybe.

Ok...I think maybe I've got it. At least based on the '09/10 catalog I found online. Not included are Single Use, LMS and DMS...this is only RMS. I can't guarantee the accuracy or the usability, but if others like it, I'm happy to fix any errors.

Yellow are incompatible families, Green are potentially exclusive cases, pink are odd-ball offspring (don't fit in with rest of model), purple are major families, blue are closure options, orange are requirements for certain configurations, not optional. Red dashed lines are connectors- branches share a feature, like similar closures.

 

[soopirV]

Only point made here is that planning and simplicity seem to be forefront with CTI.

 

[CzTeacherMan]

Only point made here is that planning and simplicity seem to be forefront with CTI. View attachment 300490

Precisely

 

[soopirV]

Precisely

I really appreciate how you were able to categorize information in your table, and I like that you seem to feel similarly to my more graphical representation. What exhausts me on these forums are the endless "fan-boy" battles between the families. Do you, CzTeacherMan, as a reasonable and sound individual (in my opinion, your friends/spouse may disagree), have any advice for AeroTech that would help them?

here is my short list- if others contribute, maybe we post this over on the AT Open Thread so it gets to Gary or whoever is in charge now.
1) "have a strategy. Stop creating single-point solutions (like FSD- make it work on all, or design so it's not required on any)".
2) "Commit to your design. Every design needs o-rings, we get it- it costs less if we install them than it does if you install them (price dif between CTI and AT); be consistent. Use the same type in the same spot every time."
3) "Future proof yourself. This is hard, but if you know you've engineered a solution to a specific and unique situation, take a step back, and ask how this can either improve every other configuration, or be evolved out by design change."
4) "Documentation is your friend. And your enemy. Right now guys on this thread are admitting to carrying around pages and therefore pounds (ok, ounces) of paper to make sure they follow the right process when they launch a potentially lethal missile into the air. One mistake kills a cub scout, as someone thankfully (and regretfully!) shared! These aren't 1oz cardboard tubes...if you design a system that can be assembled incorrectly, and yet still expect the consumer to be at fault when that design is assembled incorrectly and causes bodily or property damage, you need a better lawyer...whoever is on your legal team and said this was a defensible strategy is off his or her rocker.
5) "Nothing is cheaper than a repeat consumer." I'm abso-LUTE-ly THRILLED that this thread has generated such constructive dialog- I almost abandoned it several times because I've seen how sour discussions can go when the question is, "Which one is better? CTI or AT?". Do your job well, do it with integrity and quality, and we will continue to be partners. AeroTech does a fantastic job with innovation, with quality, and with diversity, but by focusing on being "cheaper" than their competition (the wind-chime ad comes to mind), they're doing a huge disservice to themselves. McDonalds saved hundreds of thousands of dollars (the exact figure is very hard to find- if someone can, please post!) by off-loading the drink-filling operation to the consumer, instead of making the cashier fill the cup. "but now I can drink 10 gallons of coke, and surely that costs money!" you argue. Sure, you can but you don't. That 15-20 second task repeated hundreds of times a day adds up to real savings. That's why CTI reloads cost more than AT...however, the sensitive bits that seem to catch people up (myself, specifically) are already performed by CTI, so I don't have to worry about it.

This is borne out in numbers, and as a notorious cheapskate, I'm perhaps hyper vigilant. My wife and I have fixed contributions to our hobby-accounts, which are held separately from our combined checking and saving. We are doing fine, but we recognized early on that fiscal exuberance is tough to stomach, so if a purchase that seems wildly extravagant to the other party (read: 98mm carbon fiber tomach for me, or...whatever...I don't know, eyelash transplants for her?) it can be executed without guilt or explanation. This means I need to make every penny count. I recently deduced that using my existing CTI hardware at 29mm (the most sensitive price point for CTI, since it is more expensive per Newton than AT at the smaller diameter), which includes a 3g tube, a 6g tube and two spacers (with an aft closure),I would need to fly 40 times to break even given a reasonably expensive source (generally above MSRP, but great service, and we all know which site I'm talking about). Although I'd LOVE to fly 40 times in a year, I am happy to shoot 3-5 times...so for me, I'll stick with CTI.

 

[eggplant]

Ok...I think maybe I've got it. At least based on the '09/10 catalog I found online. Not included are Single Use, LMS and DMS...this is only RMS. I can't guarantee the accuracy or the usability, but if others like it, I'm happy to fix any errors.View attachment 300489

Yellow are incompatible families, Green are potentially exclusive cases, pink are odd-ball offspring (don't fit in with rest of model), purple are major families, blue are closure options, orange are requirements for certain configurations, not optional. Red dashed lines are connectors- branches share a feature, like similar closures.

There's absolutely no difference between the "high power style model rocket RMS" and "high power RMS" categories. Those casings just happen to be small enough to have mid power motors in them. You can simplify the chart by removing that whole branch as it is redundant.

 

[eggplant]

Only point made here is that planning and simplicity seem to be forefront with CTI. View attachment 300490

Before anyone calls me a "fan-boy": I fly three brands of motors, including the two discussed in this thread.

What about tapered aft closures, spacers, XL spacers, threaded forward closures, retaining rings, or the two separate generations of 75/98mm hardware? I don't think this chart is at the same level of detail as the AT one.

I don't find Aerotech's product line particularly difficult to understand. The process is very similar to what you do with CTI. Weigh your rocket, decide what class of motor you want, and find it in OpenRocket. When you are trying to find a motor on the field, the total impulse is printed right on the package just like CTI, along with the burn time, a thrustcurve, pre- and postburn weights. I agree that AT has many pieces of hardware available, but most of them are only important for a very specific style of flight that the average user wouldn't care about, similar to the tapered/threaded closures from CTI. Basically, if you have the motor hardware listed on the reload package, you are set. The other source of confusion that I see is AT's RMS-EZ experiment. I see this as roughly equivalent to the two generations of 75mm/98mm CTI hardware. A company changing something about their product line is bound to cause confusion among the users of the product, but that doesn't mean that either brand is not "committed to [their] design". In fact, I would argue that AT is more committed to their design as every diameter of case looks and functions almost exactly the same, while with CTI you have 24mm/29mm that are nearly identical with the aft closure threading into the case, 38mm where the aft closure is part of the reload, 54mm with a closure that threads on the outside of the case, and 75mm/98mm which now use AT-style closures but previously featured an entirely different system of retaining rings and floating closures.

I used an AT motor for my L1 and a CTI motor for my L2. I have never had to carry about "pounds" of paper for any brand of motor. Follow the instructions that are included with the motor and try to not crossthread the closure (Pro38) or miss an O-ring (AT/big CTI). Never assume that following the instructions will automatically lead to a successful flight (see the Pro38 FC issues, VMax delays, and AT "sponge grains"), but instead pay attention to every stage of rocket construction, prep, and flight to make this hobby as safe as possible.

 

[Buckeye]

......but I am a successful L2........

I see that the AT F39 (24/40) and the AT F40 (29/40-120) are REALLY close on average impulse, ..........

The problem here is many people continue to confuse impulse and thrust. 39 and 40 are average force values, not impulse. Big difference. The L2 exam covers this.