Fiberglass 2.6" Single-Deploy Parachute Size Question

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asomr1

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I'm working on my level one cert vehicle which is a 2.6" fiberglass Madcow Super DX3. Once all the misc hardware is installed, it will weigh about 5 lbs. Everything I can find online suggests that I should aim for a ground impact speed of 17-22ft/s but according to OpenRocket, that suggests I'll need a 45"-50" parachute (50"=19.6ft/s ground impact velocity). Given that it's a 2.6" airframe, I'm concerned a parachute of that size won't fit wrapped in a Nomex blanket and if it does, I imagine just barely. How tight of a fit should it be? If it doesn't fit, what are my recovery options? Currently looking at the PAR-50 from Top Flight Recovery but it doesn't appear that they list packed diameters, unfortunately. Many thanks. -JT
 
I fly my Wildman Competitor 2.6" that weighs 5 lbs on a 30" Top Flight parachute. No problem fitting it and a 12" nomex protector in the airframe. I'd rather get it down a little quicker, it's an FG rocket so I'm not too worried about the landing speed. My Eggtimer Quantum says landing speed was about 30-35 ft/s on the last couple of flights.

The Top Flight chutes pack really small. I'm sure a 50" could fit in there if that's what you wanted.

cheers - mark
 
Most parachute manufacturers post descent rates. These will vary based on design. After you get your L1 under your belt you may want to have more than one size chute for different wind conditions, altitude, etc.
Also, the type of surface should be taken into account. I live in the desert where the ground is very hard. I shoot for 15-20 fps descent rates.
 
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Consider one of the Top Flight Crossfire chutes. They are higher drag than a regular chute. At 80 ounces the calculator I use suggests a 70 inch regular chute for a 15fps descent. A crossfire 36" is good up to 6lbs.
 
I'm working on my level one cert vehicle which is a 2.6" fiberglass Madcow Super DX3. Once all the misc hardware is installed, it will weigh about 5 lbs. Everything I can find online suggests that I should aim for a ground impact speed of 17-22ft/s but according to OpenRocket, that suggests I'll need a 45"-50" parachute (50"=19.6ft/s ground impact velocity). Given that it's a 2.6" airframe, I'm concerned a parachute of that size won't fit wrapped in a Nomex blanket and if it does, I imagine just barely. How tight of a fit should it be? If it doesn't fit, what are my recovery options? Currently looking at the PAR-50 from Top Flight Recovery but it doesn't appear that they list packed diameters, unfortunately. Many thanks. -JT

OpenRocket makes generic assumptions about the parachute CdA. The manufacturer's tables should be more reliable.

Topflight Thin-Mil and Apogee's lightweight nylon chutes pack very small. I like Apogee's chutes, as they are silky soft and economical, though made in China.
 
I have an Apogee parachute that I use with my Madcow 2.6" Hawk.
Very affordable chute and works well. Attached with a swivel and use a Jolly Logic Chute Release.
Apogee parachute.jpg
 
You should have no problem getting a 45" or 50" into a 2.6" tube on a DX3.
My 3" Starship Vega uses a 70" standard (not the thin mil) Top Flight chute. It is tight but it just means I have to pay attention more when packing it.
 
You should have no problem getting a 45" or 50" into a 2.6" tube on a DX3.
My 3" Starship Vega uses a 70" standard (not the thin mil) Top Flight chute. It is tight but it just means I have to pay attention more when packing it.
Thank you!
 
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