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Arsenal78

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Needing a chute for my 5.5 LOC Goblin and I noticed on Top Flight’s webpage, they claim a 50” chute will work for a 7-9lb rocket at 17-22ft/s. I’m assuming the 17ft/s is for the 7lb. Can anyone confirm these numbers? I’ve always been told a 6ft chute for 7-9lbs with a 17ft/s descent rate.
 

timbucktoo

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Does your wight include the empty motor case? I have a Frenzy that weights 7.4 lbs and use a 50" TFR chute and it comes in about 20-25 fps.
 

ThirstyBarbarian

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My feeling is it should be a bit bigger than that. My Warlock was in that weight range and came with a 58” flat chute that was almost identical to a Top Flight chute, and I kept getting fin damage. I think the descent rate was OK, but it tended to swing a lot. If you go with a brand with a spill hole, it will reduce the swinging. Spherachutes are pretty nice and tend to come down nice and stable. They do cost more, but not ridiculously expensive.
 

timbucktoo

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This chute calculator pretty much agrees with my actual flight data.
I have found that many advertised descent rates to be a little optimistic.
 

crossfire

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This chute calculator pretty much agrees with my actual flight data.
I have found that many advertised descent rates to be a little optimistic.
I believe many of chute calculator just want to cover their butts and over chute size rates.
 

Arsenal78

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My feeling is it should be a bit bigger than that. My Warlock was in that weight range and came with a 58” flat chute that was almost identical to a Top Flight chute, and I kept getting fin damage. I think the descent rate was OK, but it tended to swing a lot. If you go with a brand with a spill hole, it will reduce the swinging. Spherachutes are pretty nice and tend to come down nice and stable. They do cost more, but not ridiculously expensive.
I had planned on getting a BAMA chute but he's been having a lot of personal stuff the past few months. I might just get a 70" Top Flight and hope it works.
 

GalantVR41062

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I used a 70" TFR standard chute in my L2 rocket. Decent weight was 6.5lbs, decent rate was 11-12fps. I have switched it to a TFR 50" standard and am seeing 17-18fps now. The rocket descends at 45-48fps under drouge.

~John
 

crossfire

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I had planned on getting a BAMA chute but he's been having a lot of personal stuff the past few months. I might just get a 70" Top Flight and hope it works.
I had TOP Flight put spill holes in 2 Par30s. So I would guess they would do it on a Par70. A lot depends on your landing surface when choosing a chute.
 

Arsenal78

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I could split the difference and go with the 58” chute. I’m flying in a farm field so the land will be a bit soft
 

ThirstyBarbarian

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I think the 58” is fine in terms of descent rate, but if they can put a spill hole in it for stability, it would be even better.
 

teepot

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Try TFR's X-Form chutes. There is no swinging during decent. I use parachute size calculator to pick the right chute. Its suggested decent rate agrees with my altimeter 3.
 

Bat-mite

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What surface are you landing on? Goblin's have slightly downswept fins, so you want to protect those corners. Soft grass and mud will afford you a smaller chute than hardtack or a parking lot.
 

Arsenal78

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What surface are you landing on? Goblin's have slightly downswept fins, so you want to protect those corners. Soft grass and mud will afford you a smaller chute than hardtack or a parking lot.
The area will be farm land at Bama Blastoff.
 

Arsenal78

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I won’t be able to get a spill hole in the chute as I’ll be picking it up from a vendor at the field. I’ll stick with a 58” and add a swivel.
 

Arsenal78

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Anyone happen to know the CD of the chutes? I'm assuming since it's a flat panel chute, it will be about 0.75-0.8.
 

Arsenal78

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So 15ft/s descent on a 58” for a roughly 7.5-8lb rocket? Didn’t know flat panel chutes had that high drag.
 

Tobor

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I've flown my LOC Goblin once at Bong. I used a 48" chute. Lost track of it at apogee. Found it about 40 minutes later and discovered the Goblin came in under a tangled chute. Only damage from the landing was some chipped paint on the bottom, outside corners on two fins.
 

Banzai88

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Generally speaking:
X Type=.5
Flat=.8 (Top Flite or others that essentially 'lay flat' or are a single piece of fabric)
Cupped Parabolic=.97 (Rocketman, recon, sky angel, etc)
Annular=.99 (shaped like a ring)
Elliptical=1.5 (Fruity, etc)
Torroidal=2.2 (Fruity Iris, etc)

This all matches my personal flight data from OR as well.
 

Arsenal78

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Generally speaking:
X Type=.5
Flat=.8 (Top Flite or others that essentially 'lay flat' or are a single piece of fabric)
Cupped Parabolic=.97 (Rocketman, recon, sky angel, etc)
Annular=.99 (shaped like a ring)
Elliptical=1.5 (Fruity, etc)
Torroidal=2.2 (Fruity Iris, etc)

This all matches my personal flight data from OR as well.
That sounds more realistic. 0.8 would be a 70" chute which makes more sense to me.
 

crossfire

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A lot of the numbers never mention the priostory of the fabric. Some ripstop nylon will let some air through it. Other ripstop with a heavy coating let no air through.
 

crossfire

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I truly believe the TFR numbers as the chutes were all tested in the Space Shuttle assembly building many years ago.
 

Arsenal78

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Alright I'll trust Top Flight's numbers this time and go with a 58" chute.
 

Arsenal78

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Certed over the weekend with the Goblin. Used a 58” Top Flight chute and it was definitely too small. I’ll need a 70” next time.
 
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