beantownJPL
Up up and away... Wait! Come back!
I've got a (mostly) stock built Mean Machine that I've got probably 10 flights on D12 and E12. I like this model a lot and it's a great flyer. The modifications I made to the original build were to use the longer Apogee tube couplers (3" instead of 1.5"), an Apogee ejection baffle and rail guides as well as lugs (which I upgraded to 1/4").
While it's a great flyer, it is just a bit delicate. After 4 or 5 flights on its first day, it was taking a beating. I had to re-glue fins, and on the last landing, it lightly kinked the lower-most body tube. I repaired the tube by cutting at the kink, and adding a coupler. Flew it again this last weekend, and it snapped off a fin on landing again, but no other damage.
It's a big long lever, and 6' of BT-60 hitting the ground tail first is a fair bit of energy. The kink occurred just where you'd expect a 6' stick to break if you hit it on the ground. I could use a bigger 'chute, but that just means longer walks, and a greater chance of decorating a tree.
Long story short, Estes has warrantied me a new one because (unrelated to any overall design issue), I had a "shotgun ejection" that tore out the motor hook and ejected the motor. So, I'm going to build this one a little different.
I plan to discard the plastic coupler and add an Apogee coupler in the middle with a bulkhead and screw eye, to which I will attach one 15" 'chute. The lower half receives an ejection baffle at the lower coupler location, also with a screw-eye to which I'll attach a second 15" 'chute. On deploy, the two sections completely separate, and come down independently.
My only concern is ensuring both 'chutes deploy. While I'm fairly sure the ejection charge will be sufficient to blow out the laundry, not having the nose cone pulling the lower 'chute out is a lost redundancy.
Options I've considered:
My posts on this build for those who wish to follow along:
While it's a great flyer, it is just a bit delicate. After 4 or 5 flights on its first day, it was taking a beating. I had to re-glue fins, and on the last landing, it lightly kinked the lower-most body tube. I repaired the tube by cutting at the kink, and adding a coupler. Flew it again this last weekend, and it snapped off a fin on landing again, but no other damage.
It's a big long lever, and 6' of BT-60 hitting the ground tail first is a fair bit of energy. The kink occurred just where you'd expect a 6' stick to break if you hit it on the ground. I could use a bigger 'chute, but that just means longer walks, and a greater chance of decorating a tree.
Long story short, Estes has warrantied me a new one because (unrelated to any overall design issue), I had a "shotgun ejection" that tore out the motor hook and ejected the motor. So, I'm going to build this one a little different.
I plan to discard the plastic coupler and add an Apogee coupler in the middle with a bulkhead and screw eye, to which I will attach one 15" 'chute. The lower half receives an ejection baffle at the lower coupler location, also with a screw-eye to which I'll attach a second 15" 'chute. On deploy, the two sections completely separate, and come down independently.
My only concern is ensuring both 'chutes deploy. While I'm fairly sure the ejection charge will be sufficient to blow out the laundry, not having the nose cone pulling the lower 'chute out is a lost redundancy.
Options I've considered:
- Attach a bit of thread to the peak of the lower parachute, and tape it to the inside of the upper section of the airframe.
- Add velcro to the tops of both 'chutes and stick 'em together as I load the bundle into the airframe.
- Decided --> Piston ejection. I have the parts ... might be fun. The ejection baffle should keep most of the gunk in the lower part of the rocket, so the "piston tube" should stay relatively clean. Decision made on post #8.
- Umm ... something better? -> Interesting option for future build: "Semi-drogue" described by @georgegassaway in post #16 & #23
My posts on this build for those who wish to follow along:
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