This would be old stock.Are you making VMax propellant again or is this old stock? I like the F240s.
This would be old stock.Are you making VMax propellant again or is this old stock? I like the F240s.
What are the chances that VMax will eventually return?Haven't made them for Pro X in 5 years, no plans to make them in the near future.
We do however still have Pro24 and Pro29 VMax available, as well as AMW 54 3 and 4G
I'm glad you mentioned that the L395 can be used with the AMW case and the hub cap. I have that combination in the works for an upcoming flight, but won't have any fallback if this were not to be feasible. Relieved to see that this works.
By the way, I hope no one is using the forward closure as a push point. Seems like a bang just waiting to happen.
Jim
I'm hoping it fits right into the 5 grain case.Any 75mm load should be compatible with equivalent AMW hardware. And if your case is too long, up to two spacers can be used.
There are currently no plans for making VMaxWhat are the chances that VMax will eventually return?
Likely won't be many new propellants in the near future, but we are planning on certifying some more existing propellants, the Pro29 IM and more mellow are on the list.
So a thrust ring that contacts only the case front (a la Estes) would be OK then?I understand what you're saying. When the motor is under pressure there is enough force on the forward closure to withstand the push from the motor. From my point of view (not saying it's the right point of view ), since the forward closure isn't fixed to the case mechanically I wouldn't use it to push on.
I beleive on AT cases the forward closure screws onto the case, those I wouldn't have an issue with.
That would be fineSo a thrust ring that contacts only the case front (a la Estes) would be OK then?
What sort of motor burning would result in the forces not being applied in the appropriate directions and keeping the forward closure in place? I can't think of any.The physics are fine as long as the motor is burning normally. Are there any conditions or motor types where this would not be the case? I'd be curious to hear from CTI on this as well.
I would point out that the motor isn't designed to perform this function and that the method brings other factors into play. Just some things that occur to me are what length of threaded rod will this work for - if the rod is 3/8 or 5/16 for example. Can I push on a 3-foot length of all thread? If the thrust is transferred to a bulkplate at the top of the coupler, then that bulkhead would take all of the force. You wouldn't design a motor mount with all of the force transferred to a glue joint on one centering ring? Is the bulkhead itself strong enough? Are the treads on the closure and the point where thrust is applied up to the task?
I was reviewing a college project earlier this year where, as best as I could tell, they were proposing this technique. I asked about it but things got derailed before they answered. But the above were a few things I was asking about for their project.
Jim
Almost all AT motors are indeed certified in CTI Hardware. They will have a crossload sticker on them and very few do not now days.I use 75 and 98 CTI motors in AT cases regularly. Most CTI loads are certified in AT hardware. The reverse is not true. There are a few AT loads certified in CTI hardware but not many.
Three threads or 50, strength is the same. Three is magic number. An aircraft engineer told me that once, I don't know the mechanical engineering or physics behind it.Here's a pic of the Gen2 Boat Tail. I'm sure it has been tested by CTI, so I'm not saying that it hasn't. I plan on screwing this on to the end of a 5800 for a Mach 3 attempt. There are only three threads holding this on. How much force can three threads take? Not only the thrust but the weight of the rocket pushing against those three threads. I don't know all the numbers here, but I do know that I will be giving the Gen 2 Boat Tail a helping hand on this flight by sharing some of the load with the front of the casing. What do you think?
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Three threads or 50, strength is the same. Three is magic number. An aircraft engineer told me that once, I don't know the mechanical engineering or physics behind it.
Three threads or 50, strength is the same. Three is magic number. An aircraft engineer told me that once, I don't know the mechanical engineering or physics behind it.
Three threads engagement is a rule of thumb which works in most situations most of the time. When you get to situations where the threads are significantly loaded or there are some other relevant factors (for example, perhaps you want reduced engagament for some reason) it is wise to do the proper calculations. These days it would likely be FEA on CAD-based designs.CTI must have known this! I most certainly did not. If three is magic number, why would you ever use more than three on anything with threads?
Perfectly phrased. There will always be situations where that rule of thumb is marginal like for applications that are constrained to non standard fine threads (maybe due to wall thinness), but for standard threads, it should hold pretty well.Three threads engagement is a rule of thumb which works in most situations most of the time
An N5800 will generate shear stresses of about 1,500psi in those threads. The shear strength of 6061-T6 is 30,000psi.Here's a pic of the Gen2 Boat Tail. I'm sure it has been tested by CTI, so I'm not saying that it hasn't. I plan on screwing this on to the end of a 5800 for a Mach 3 attempt. There are only three threads holding this on. How much force can three threads take? Not only the thrust but the weight of the rocket pushing against those three threads. I don't know all the numbers here, but I do know that I will be giving the Gen 2 Boat Tail a helping hand on this flight by sharing some of the load with the front of the casing. What do you think?
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It may stop the parts unscrewing, but it won't do anything to reduce shear loadings on the threads.Three may be the magic number, but non-permanent thread locker is the magic salve.....
Almost all AT motors are indeed certified in CTI Hardware. They will have a crossload sticker on them and very few do not now days.
According to the AT Crossload chart it shows all 75mm combos but stops at the 4g reloads.
I know for a fact the M1850 and seal disk will not fit in the CTI 6g case. I tried it. Closure will not engage enough threads to make it reliable. I'm guessing the same goes for the AT 5g loads since it's not on the chart either.
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