LOC Goblin under the 36-inch 'chute?

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JonathanOtt

JonathanOtt

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Just curious how everyone's Gobby's are recovering under the LOC 36-inch 'chutes? Or, anyones 3-4 lb. rockets for that matter...

This probably belongs in the Recovery Forum, but I already typed a lot, and this phone the Gov't gave me has been castrated and lobotomized (can't copy and paste), so I can't move it without retyping the whole thing.

So....

I was thinking about having our extremely talented with a sewing machine cousin sew me up a 'chute or three from one of the patterns available on the interwebs.

I like the way the Scott Bryce (scottbryce.com) patterns generate a hemispherical 'chute with any number of gores; and Chuck H. had a post in the recovery forum abouts the Vatsaas Bros Parachute Template that has a neat shape to it and would look good in two colors.

So, getting around to the point, if I commissioned a hemispherical 'chute using Scott Bryce's pattern, what size should I do, and what about a spill hole? It'll have one, just not sure what size.

His calculator says 53" for a 48 oz. payload, with a 15 fps descent rate. If I go larger, say to 60" or 65", what size spill hole to get me into the 12-15 fps descent rate? His calculator doesn't change numbers if you put a specific spill hole diameter in.

On the other hand, the Vatsaas pattern calculator comes up with a 48" (I think)...but it is a unique shape.

Thanks for your help. (I'm a TLAR guy, (that looks about right) and do not have a math background, or I'd probably be able to figure it out.

Jon
 
Last edited:
I don’t have a LOC goblin. I do have a loaded 3.34 pound Wildman RB-05A sport that I’ve recovered successfully with a high lift high drag coefficient fruity chute IRIS 24” drogue at a standard descent rate of 25 FPS.

Typically what you can do is put the rocket measured design geometry and many masses into open rocket. Then simulate for different sized chutes. Or go the old school route and bust open Apogee rockets techie articles like sizing your rocket parachute and they walk you through using units and doing algebra by hand. I prefer both methods.

What’s really at play here is mass of rocket to recover, area of chute, shape of chute, and drag coefficient of chute.

https://apogeerockets.com/education/downloads/Newsletter149.pdf

This article was sufficient for L1 multistage rocket scratchbuild design recovery parachute sizing for university work. Perhaps other Loc goblin owners will chime in or more experienced rocketeers.

Top flight chutes pack really nice and compact by the way but are not as draggy.
 
Mine weighed 3lbs on the dot without motors. I used the standard LOC chute. Next will be the new Top Flight 36" with spill hole pictured in the thread referenced above. But if your weight goes up and you're landing on hard surfaces, I can see wanting to use a bigger chute. Still, Top Flight would be a great suggestion. His thin mill chutes are super easy to fold and pack. And more than durable for a Goblin.
 
JonathanOtt said:
Just curious how everyone's Gobby's are recovering under the LOC 36-inch 'chutes? Or, anyones 3-4 lb. rockets for that matter...

This probably belongs in the Recovery Forum, but I already typed a lot, and this phone the Gov't gave me has been castrated and lobotomized (can't copy and paste), so I can't move it without retyping the whole thing.

So....

I was thinking about having our extremely talented with a sewing machine cousin sew me up a 'chute or three from one of the patterns available on the interwebs.

I like the way the Scott Bryce (scottbryce.com) patterns generate a hemispherical 'chute with any number of gores; and Chuck H. had a post in the recovery forum abouts the Vatsaas Bros Parachute Template that has a neat shape to it and would look good in two colors.

So, getting around to the point, if I commissioned a hemispherical 'chute using Scott Bryce's pattern, what size should I do, and what about a spill hole? It'll have one, just not sure what size.

His calculator says 53" for a 48 oz. payload, with a 15 fps descent rate. If I go larger, say to 60" or 65", what size spill hole to get me into the 12-15 fps descent rate? His calculator doesn't change numbers if you put a specific spill hole diameter in.

On the other hand, the Vatsaas pattern calculator comes up with a 48" (I think)...but it is a unique shape.

Thanks for your help. (I'm a TLAR guy, (that looks about right) and do not have a math background, or I'd probably be able to figure it out.

Jon
Click to expand...
 
A 36 inch chute should be adequate...maybe 42 ... for that rocket at three to four pounds. You should have open rocket or Rocsim software to model decent rates if you are asking questions of this detail. Several excellent vendors out there... Spherachutes, Top Flite, Skyangle, others.
 
7 flights on mine so far. Used the stock supplied Loc 36" chute for the first 6 flights and the Top Flight 8 panel 36" for the most recent. Both excellent choices; no damage from any landings....even on frozen ground, and a descent rate that looks about right.

Have used the Jolly Logic Chute Release to minimize drift for the higher flights.
 
ECayemberg said:
7 flights on mine so far. Used the stock supplied Loc 36" chute for the first 6 flights and the Top Flight 8 panel 36" for the most recent. Both excellent choices; no damage from any landings....even on frozen ground, and a descent rate that looks about right.

Have used the Jolly Logic Chute Release to minimize drift for the higher flights.
Click to expand...
The Jolly Rodger works!!! Although I don't have the proper grasp yet! =}
 

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