Parachute Sizing

[Doug GerrardParticipant]

I went back to the altimeter data from my “Just Do It” flight.

The descent rate under the RRQS70 main was right at 20fps for a rocket that would have weighed 38 lbs 6ounces after propellant burnout.

Ed, that matches my data. On Freeze Frame using a RRSQ130 it’s descent rate was 25 fps with a weight of only about 60 pounds. BDCR’s flights showed the same results on the RRQS70. That’s why I use the rule of thumb to use double the size you need to get the 20 to 25 fps. I always try to rely on empirical data rather than

eyeball guesstimation

Doug

[Chris LaPanse]

I went back to the altimeter data from my “Just Do It” flight.

The descent rate under the RRQS70 main was right at 20fps for a rocket that would have weighed 38 lbs 6ounces after propellant burnout.

Ed, that matches my data. On Freeze Frame using a RRSQ130 it’s descent rate was 25 fps with a weight of only about 60 pounds. BDCR’s flights showed the same results on the RRQS70. That’s why I use the rule of thumb to use double the size you need to get the 20 to 25 fps. I always try to rely on empirical data rather than

eyeball guesstimation

Doug

I love out of context quotes 🙂

As I said, I am ignoring the data from the RRQS15 because that’s all that it is based on. I have actual data however from a RRQS50 with 29lbs of weight (after burnout), and it shows 9-15fps. I can post that data if you like – it was taken with my R-DAS, and is quite clear.

[MikeSModerator]

I broke down and ordered a 70″ Top Flite. Should do the job.

Thanks for all the help.

[Doug GerrardParticipant]

Mike, I saw the picture of your rocket posted elsewhere. Good luck! Please post the descent rate here after you fly it. Maybe we should start a pool to guess the descent rate? Again, Good luck on your level 2!

Doug

[MikeSModerator]

The white paper says.

12lb to 18 lb = 17 to 22 Ft. Per Sec. Using a 70″ standard flat chute.

I ‘should’ be less than 17 at around 10lbs loaded. I’m OK with drift.
I just want a soft landing. Plus future birds will be heavier.

I would need some help calculating the descent rate on site.
I never have.

Thanks

[Author]

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