As I’m building my kit from North Coast Rocketry, there is no engine block or retaining hook...does one just friction fit the SU in place or does one apply epoxy to the little cardboard ring that comes with the motor and use that with the retaining ring?
As others have stated, many rocket models are sold with-OUT positive motor retention assemblies, and it is up to the building to do something about it.
That is definitely the case with many NCR, LOC, and virtually all fiber-glass HP kits.
Positive motor retention, with simple thrust rings made out of masking tape, or similar (when none are present on a motor), are the easiest and the most reliable way to go.
I just went and checked, all of mine have thrust rings. Post a pic of yours.
Understood with the motors you are talking about. They are the older Econojets, and do not have a thrust ring. You could epoxy the ring on or just use masking tape for a thrust ring.
I have very few single-use AT motors, and had surprised myself to discover that a couple of those are of the old EconoJet variety.
The one pictured below, a visibly rustic F20, does not come with a thrust ring. I will have to improvise one with a few layers of masking tape on the aft end, before flying. Similar to those pictured above on Estes motors.
The ring that comes with the Econojet motors should fit over the motor, not inside the motor mount tube. Epoxy it on the nozzle end of the motor for a thrust ring.
The ring above is the same diameter as the motor. Thus, I presume, it's meant to be used as a spacer. Similar to those that Estes uses to make D12 motors fit in a MMT that had an engine block glued in for an E12-sized motors.
It will definitely NOT fit over the motor, nor should it be epoxied to it.
I am throwing mine away, as I never EVER use Estes-style motor blocks.
Instead, I rely on masking tape thrust rings, and positive motor retention. Way more reliable, more flexible (can fly motors of any length), cleaner, and more elegant.
CoachSteve said:
Friction fit (tape wrapped around the motor case until a tight fit in the motor tube) - has beed used since the beginning of rocketry and is regularly used well above D power motors.
And people like me, who don't take enough care when friction fitting an I motor, end up losing a motor case and destroying a rocket.
That's very true.
I've found, and occasionally returned (when I could find the owner) about a half dozen motors that were friction fit by other people.
I am yet to pay for a CTI motor/case, yet now have 3 in my inventory, due to the unintentional and involuntary donations by the friction fit aficionados.
If you fly in NJ/NY area and have lost a friction-fitted motor, PM me something unique about the case that you've abandoned. If I have it, I will be happy to return it to you.
Otherwise, thanks in advance to yo'all who are continuing to friction fitting your motors!
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