SHOWTIME: Level 2 Re-Attempt After Epic Fail. MAC Performance Firestick XL With Redundant Dual-Deploy. Project Hurricane is Go For Launch.

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GAP

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One other note; OpenRocket does NOT account for spill holes. So real decent rates will be a little faster when the chute has a spill hole.
This is not necessarily true. On the right chute (and in fact most chutes) spill holes can actually increase the Cd.

On another note I'll mention I land my Punisher 3 at 28 fps all the time. Albeit, on soft grass and it is a fiberglass kit.
 

StreuB1

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My 9.5lb LOC Minie Magg that is stretched for dual deploy comes down on a 72" cruciform chute. A 50" chute for a 9.5lb rocket is really really small. Add a spill hole and its even worse.
 

FlyBy01

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dr wogz

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If I recall, this is Mike's [MAC Performance] canvas airframe tubes / Kit. Have you spoken to Mike to see if maybe a bad batch of tubes, if maybe there was something extra needed in the prep? Or at least to tell Mike of the failure?
 

Mach_Seven

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If I recall, this is Mike's [MAC Performance] canvas airframe tubes / Kit. Have you spoken to Mike to see if maybe a bad batch of tubes, if maybe there was something extra needed in the prep? Or at least to tell Mike of the failure?
Mike has been in touch with me through the whole build. It seems to be a combination of undersized chute, poor bonding on the forward centering ring, and impact with unforgiving pavement. It was a hard landing. Just look at what it did to the aluminum retainer:
9BCFF8E4-1EFA-4B06-8709-807C1FB6EE22.jpeg

I received a lot of good input on how to repair her. It ain’t rocket surgery! Oh, wait. I guess it is. She’ll fly again soon. With a new 72” Rocketman chute onboard.
 

dr wogz

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Super, just wanted to state the obvious!

As one particular other said: put it a side, and think about the repair. Don't jump into it.. think about how you want to proceed
 

Mach_Seven

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Super, just wanted to state the obvious!

As one particular other said: put it a side, and think about the repair. Don't jump into it.. think about how you want to proceed
This is great advice and exactly what I'm doing. Another rocket junkie just texted me asking how the repair was going. I'm like, "Are you kidding? I'm too scared of %$#*ing it up to even touch it right now!"
 

dr wogz

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yeah, it's like when you get some surgery.. you don't immediately look at the wound! or try to flex the area too much!
 

Steve Shannon

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Is it likely that you prepared the tube similarly when you epoxied the other centering rings? Might their glue joints also pop? If so, you might want to simply start over with a new tube.
 

Zbench

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Scott Bryce has an excellent resource located at: http://scottbryce.com/parachute/spherical_parachute.html

I routinely use the calculator to estimate the size of the parachute and then generate patterns and stich up my own. It has never let me down, except of course in the range that was intended!

Guessing your rocket will be around 8 pounds once the propellent has burned out. That would indicate an 86" diameter chute for 15 fps decent rate. It's worth mentioning that the parachutes that come with LOC kits are flat sheets and don't have nearly the drag that a properly stitched multigore spherical cute does. I size my chutes with a 6-12" spill hole (larger spill hole for a larger chute) using a 25% sphere. As for number of gores, I just play with it so it will mostly fit on a portrait sized 8.5 X 11" piece of paper. It will print out on multiple sheets, cut and tape together. I cut out a pattern on luan plywood which makes it very easy to cut the gores.

On the chutes I make, I use a quality serger with a 3 thread narrow seam stitch. It has worked very well for me. Either way, the calculator makes a great resource to size a parachute.
 

Swany

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I would agree that 24 fps is too high especially on pavement.
When thinking about "proper" descent rates, I like to think in terms of an equivalent drop height to get a more intuitive feel. For example, 24 fps is roughly equivalent to getting up on a ladder and dropping the rocket from a height of 9 feet. On relatively soft grass, that's probably OK (although still higher than I would be comfortable with). But on asphalt, probably not - especially with a phenolic airframe.
 
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Mach_Seven

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bobbyg23

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From Spherachutes.com.
 

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Homer_S

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Here's a model rocket someone made of Showtime 100...


View attachment 493022
Grew up in Tampa, FL. Used to see these in this livery screaming off the runway at MacDill.

iu


Occasionally in this one.

iu


Homer
 
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