Mean Machine Twist Lock Coupler

[MALBAR 70]

I'm in the process of building a Mean Machine (1295) with the twist lock coupler. I was considering replacing the coupler with a bulkhead and making the upper half a payload bay, like I've done with other long rockets I've built.
I was curious what the consensus was on the twist lock coupler.

 

[user 35280]

I’ve seen two different launches at my local club and both times those rockets separated at the twist lock and the BT’s ended up being damaged by the hard landing. I have a mean machine kit but I’m going to kit bash it into something else.

 

[Scott_650]

My MM with a twist lock coupler has worked fine for roughly a dozen launches - I put my payload bay in the upper section and kept the twist lock since it simplifies transport and storage. I modded my Custom Rockets Equinox to separate in the middle and that works well too. You probably can go either way and not see much difference in performance.

 

[katinthebox]

Really? I just finished painting mine this afternoon (and was right about to post a pic) and I'm really impressed with how sturdy it feels + how strong that part of the whole assembly seems.
Any recommendations? I'm really happy with how this one turned out, I'd hate to have it tear itself apart if I can avoid it!

 

[Scott_650]

Really? I just finished painting mine this afternoon (and was right about to post a pic) and I'm really impressed with how sturdy it feels + how strong that part of the whole assembly seems.
Any recommendations? I'm really happy with how this one turned out, I'd hate to have it tear itself apart if I can avoid it!

I’ve never had a problem with mine but you could put a quick wrap of electrical tape around the coupler just in case it tries to disengage.

 

[mo2872]

I nixed the twist lock. I used a coupler and added a bulkhead and pop it at the middle instead of the nose cone.

 

[katinthebox]

I’ve never had a problem with mine but you could put a quick wrap of electrical tape around the coupler just in case it tries to disengage.

Honestly, my first thought reading this was the tube on either side of the coupler would be the weak point(s)... like if it landed wrong, the inner end of the plastic would put too much force on the cardboard and split it.

 

[bjphoenix]

A bulkhead in the middle sounds like a good idea. I would be concerned about the volume of the entire airframe that has to be pressurized by the ejection charge. Cutting that volume in half should help.

 

[neil_w]

A bulkhead in the middle sounds like a good idea. I would be concerned about the volume of the entire airframe that has to be pressurized by the ejection charge. Cutting that volume in half should help.

Loooong shock cord to ensure that the two halves of the rocket won't be banging into each other on the way down.

 

[bjphoenix]

Loooong shock cord to ensure that the two halves of the rocket won't be banging into each other on the way down.

I use 10' kevlar in LPR. If I was building a MM to full length maybe it would need a longer cord. (I am building one but not full length and it will look like something else when finished.)

 

[teepot]

My MM with the twist lock has never come apart in flight. It has a bunch of flights. It was one of the big rockets I did several years ago. It has always flown well.

 

[charles.garnes]

I'm in the process of building a Mean Machine (1295) with the twist lock coupler. I was considering replacing the coupler with a bulkhead and making the upper half a payload bay, like I've done with other long rockets I've built.
I was curious what the consensus was on the twist lock coupler.

I messed up installing the twist coupler by using CA glue so I ended up using 3 plastic rivets in a longer cardboard coupler. Works great!

 

[Back_at_it]

I too have seen two flights where the twist lock coupler came apart in flight. One under thrust and the other at ejection.
But then again I have also seen about five or six where they flew just fine. I personally didn't want to take the chance.

When I built mine I replaced the lower coupler with a 4in. section and replaced the twist lock with a 4in coupler. The upper tube is a payload bay and is held in place with a 5in coupler. 2in is glued in the upper tube while 3in. extends down into the tube for better support during thrust.

 

[neil_w]

Are they actually untwisting in flight? If so, can they simply be made a bit tighter with some strategic use of blue tape?

 

[MidOH]

Weird that people actually build these.

Estes might not know it, but we used to buy these to repair a dozen other BT60 rockets, and have one nice new normal sized one. Same with the Commanche 3. In the 80's the builders kit was kinda pricey, and LHS's rarely carried just tubes. Two of Estes's most popular kits were for parting out. Lolz.

 

[Back_at_it]

Are they actually untwisting in flight? If so, can they simply be made a bit tighter with some strategic use of blue tape?

Of the two I saw come apart. The coupler broke in half under thrust about 200ft off the pad. It was flying on an E20 or E30. I can't remember which. The other one untwisted. Don't recall what motor but the rocket was only up a maybe 400 ft.

 

[Back_at_it]

Weird that people actually build these.

Estes might not know it, but we used to buy these to repair a dozen other BT60 rockets, and have one nice new normal sized one. Same with the Commanche 3. In the 80's the builders kit was kinda pricey, and LHS's rarely carried just tubes. Two of Estes's most popular kits were for parting out. Lolz.

Agreed but today you can get tubes cheap from pretty much anywhere. I did buy a bunch of Big Daddy's when HL had the for $9.99 strictly for the nose cones.

 

[jmasterj]

My son and I built his to separate at the middle with a bulkhead in the upper half. We put a baffle in the lower half and used ~20 feet of Kevlar. 18" chute was still probably too much; it floated the farthest at our last launch despite not achieving even close to the highest altitude.

 

[dhbarr]

Are they actually untwisting in flight? If so, can they simply be made a bit tighter with some strategic use of blue tape?

My L1 Mammoth was held together with blue tape so that I could take it in half to put in my fairly small car. Worked great!

 

[bjphoenix]

Weird that people actually build these.
Estes might not know it, but we used to buy these to repair a dozen other BT60 rockets, and have one nice new normal sized one. Same with the Commanche 3.

I understand this and I've had the same thought.
I bought one to kit bash into something else because it was cheap at HL and because it had the nose cone profile that I wanted. Maybe I can figure out something interesting to do with the extra tubes. But back to the subject- this was the first MM I've handled closely and I noticed that the twist coupler in my kit has a relatively tight fit. I did not think it would come apart in flight. I suppose if someone was really concerned they could put a wrap of masking tape on it right at that joint.

 

[MALBAR 70]

Mine is still in the build stage and I was just wondering what most have done and if the twist lock was decent or a gimmick.
It seems to be 50/50. I like the idea of splitting it in the middle, I did my two Custom Rockets Equinox's that way.

 

[teepot]

My twist lock works fine. MM has had lots of flights.

 

[GlenP]

Have these observed coupler failures occurred with Estes recommended black powder D12 and E12 motors, or perhaps under higher kick thrust off the pad and maybe hotter composite power beyond what the kit was designed for? Flies nearly out of sight on an E12:


Or maybe did the plastic to cardboard glue joint fail due to the wrong kind of glue? (Ie non-toxic plastic cement, more like non-adhesive plastic cement)

PS - I made my own twist lock coupler/partial baffle on this recycle bin rocket (an Excalibur upscale to 24mm power, not quite as big as a MM) and I run the Kevlar line up from the engine mount and fish it through the coupler to the nose cone and chute, just in case...but it has worked great with no problems.

 

[heada]

For those having issues with the locking coupler coming undone, when you twist the sections together, are you getting a positive locking click?

Mine is 10-ish years old, maybe 7 or 8 flights and never an issue.

 

[Adam3836]

My MM has done well several flights with the twist locking coupler
Defiantly easier to transport having the twist lock

She loves flying on D12s

 

[RocketRev]

Have these observed coupler failures occurred with Estes recommended black powder D12 and E12 motors, or perhaps under higher kick thrust off the pad and maybe hotter composite power beyond what the kit was designed for? Flies nearly out of sight on an E12:


Or maybe did the plastic to cardboard glue joint fail due to the wrong kind of glue? (Ie non-toxic plastic cement, more like non-adhesive plastic cement)

PS - I made my own twist lock coupler/partial baffle on this recycle bin rocket (an Excalibur upscale to 24mm power, not quite as big as a MM) and I run the Kevlar line up from the engine mount and fish it through the coupler to the nose cone and chute, just in case...but it has worked great with no problems.View attachment 505056

Hello GlenP,

I like the looks of this upscale, but it doesn't much look like an Estes Excalibur. Is it an upscale of a different Excalibur?

Brad

 

[RocketRev]

DOH! I just realized that its an upscale of a Centuri Excalibur. Not the Estes variety.

How embarrassing to have forgotten! Sigh! it must be that old-timers again.

Brad

 

[GlenP]