Fiberglass 2.6" Single-Deploy Parachute Size Question

The Rocketry Forum

Help Support The Rocketry Forum:

asomr1

New Member
Joined
Feb 15, 2021
Messages
3
Reaction score
0
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
 

markg

Well-Known Member
Joined
Jun 18, 2014
Messages
388
Reaction score
142
Location
Windsor, Ontario
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
 

SkyFire

Well-Known Member
Joined
Oct 20, 2020
Messages
840
Reaction score
2,016
Location
Tucson, AZ
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.
 
Last edited:

teepot

Well-Known Member
TRF Supporter
Joined
Dec 8, 2019
Messages
889
Reaction score
542
Location
Pahrump, Nevada
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.
 

Buckeye

Well-Known Member
TRF Supporter
Joined
Sep 6, 2009
Messages
2,676
Reaction score
503
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.
 

SkyFire

Well-Known Member
Joined
Oct 20, 2020
Messages
840
Reaction score
2,016
Location
Tucson, AZ
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
 

T-Rex

Ordinary Average Guy
TRF Supporter
Joined
Jul 22, 2011
Messages
3,006
Reaction score
57
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.
 

asomr1

New Member
Joined
Feb 15, 2021
Messages
3
Reaction score
0
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!
 
Top