New to rocketry, jumping right in - have many questions

[kuririn]

I notice with this kit that it doesn't come with any sort of motor retainer, or a thrust ring. If I want to keep using the Estes single-use motors, what do you guys recommend I use for retention??

It's a 29mm motor mount, and they came come in a variety of lengths, so Madcow left the engine block and hook out, unlike the cardboard version that uses 24mm engines. Composite motors have a rear flange that acts as a thrust ring/motor block. Estes black powder motors do not have a rear flange, so you need to fashion one by wrapping thin masking tape, about 1/4" wide, several times around the rear of the motor. And to retain the motor at ejection you can wrap tape around the rear of the motor tube and the motor. Or you can install a plastic or metal screw on motor retainer.

 

[Nytrunner]

I notice with this kit that it doesn't come with any sort of motor retainer, or a thrust ring. If I want to keep using the Estes single-use motors, what do you guys recommend I use for retention??

Time to learn some new tricks! Estes pro series retaineres (24mm and 29mm) are plastic screw on retainers that are nice.

For the straight motors without a thrust ring, make a tape trust ring at the back of the motor. I do a wrap of 1/4" masking tape, with a wrap of 1/2" over that. Also, with the motor sticking out 1/4", a wrap or two of masking tape over the back of the motor and the mount can retain also (folks do this with high power motors in minimum diameter rockets

 

[Scott_650]

The rocket did well! Had two successful launches, and then on the third launch I lost the nose cone. The rocket landed safely, but once I picked it up I noticed the cone was gone. The knot in the kevlar cord still looked intact, so I'm guessing the plastic "loop" of the nosecone broke. I spent a while looking for the cone but wasn't able to recover it.

For my next build I'm thinking of going fiberglass - just for a stronger rocket and to learn the material.

https://www.madcowrocketry.com/1-6-fiberglass-mini-cowabunga/

I notice with this kit that it doesn't come with any sort of motor retainer, or a thrust ring. If I want to keep using the Estes single-use motors, what do you guys recommend I use for retention??

Believe it or not - masking tape, both to retain the motor and to make a thrust ring around the aft end of the motor. Works just fine, especially on Estes 24 & 29 mm BP motors. Take a look at composite type motors - both single use and reloadable style - and you’ll see what a MPR/HPR thrust ring looks like. (I typically build all my 24mm and up rockets without engine blocks so I can easily use any length/type motor.) You’ll make yours with wraps of common masking tape. Motor retention is just as simple, masking tape around the aft end of the motor overlapping the engine tube.

As far as nose cones go I don’t use the built in loop for shock cords, just parachutes. Drill a hole in the base of the cone a reasonable distance from the center hole, then either tie the shock cord directly through the two holes or put a short loop of cord - what I call 550 cord, but it’s just HD thick nylon string - and tie off the shock cord to that.

 

[PoweredBySoy]

I'll look into the masking tape idea. I have read about it before, but didn't think it would be advisable with an E motor. I did read a guy that said he's done it up to G's but that it wasn't advisable haha.

My original plan was to use reusable motors, but I can't really find what I'd need. For 29mm E motors it looks like I'd want to get the Aerotech 29/40-120, but I can't find the casing for it anywhere. It's either sold out or 'not available online'. Estes BP E's are pretty easy to find though.

As far as nose cones go I don’t use the built in loop for shock cords, just parachutes.

I didn't realize that. Lesson learned. After I had left the launch one of the other guys had found my cone in the field, so I'll get it back. I'm interested to see what it looks like.

 

[kuririn]

Instead of hooking up my parachute to the plastic loop on the nose cone, I attach it to the shock cord, about a third of the way down from the nose. This has two benefits: Less weight pulling down on the plastic loop, less stress. And less chance of the nose cone weaving in and out of the shroud lines and getting tangled up. And I attach the lines to a snap swivel, less tangling too.

 

[PoweredBySoy]

Instead of hooking up my parachute to the plastic loop on the nose cone, I attach it to the shock cord, about a third of the way down from the nose. This has two benefits: Less weight pulling down on the plastic loop, less stress. And less chance of the nose cone weaving in and out of the shroud lines and getting tangled up. And I attach the lines to a snap swivel, less tangling too.

Correct. That’s how I did it on both my builds - a swivel about 5 inches down the shock cord.

 

[beeblebrox]

I'll look into the masking tape idea. I have read about it before, but didn't think it would be advisable with an E motor. I did read a guy that said he's done it up to G's but that it wasn't advisable haha.

I have flown K-Motors with a masking tape thrust ring, use 1 1/2" tape for
2-1/8" dia. motors... That's what we did 30 years ago...Tape is cheap! 2 wraps to prevent ejection over the seam...re-use the tape after the flight and wrap another motor.

Tape sizes:
18 - 24mm 1/2" tape or 29mm with less than 80nt ave thrust
29 - 38mm 3/4" tape
54mm - 1" tape (note works fine for J700's and less)

Just don't use on super high thrust butt-kickers, then you can epoxy on a 1" piece of motor mount tube...

 

[PoweredBySoy]

then you can epoxy on a 1" piece of motor mount tube...

Oh, I really like that idea!

Once I get the motor mount tube built I'll play around with these ideas. I know I want to avoid seating the motor too far aft and running into CG issues again - like my last rocket.

 

[beeblebrox]

Oh, I really like that idea!

Once I get the motor mount tube built I'll play around with these ideas. I know I want to avoid seating the motor too far aft and running into CG issues again - like my last rocket.

You can still use a motor hook, or two, instead of putting the forward end of the hook thru the motor tube, bend it outward a bit so the top hook is touching the side of the tube. (forward of the centering ring below it) put a nice blob of epoxy there. Have the aft end of the motor tube recessed in the back a little less than the width of the tape so the end of the motor just sticks out a little bit, thus no CG/CP issues. I would use two Estes E12 size motor hooks 180 deg. apart. run one wrap of tape around them if you want. This is a crude wordless workshop as I don't have any active projects in this stage...There is no way the hook pulls out and no motor length issues. This is an E12 hook held against a 29mm tube. Mix a little balsa dust with the epoxy, it will be strong and light and will stay put while curing.