Normalizing drop test reefed drag area for suspension line length with data from Wolf allows best match of test results with Knacke reefing ratio curve. Various sizes and porosities of quarter spherical ribbon parachutes were tested. All appear to fit the published reefing ratio curve-quarter spherical parachutes match

McFadden, Peter G.

Schmidt, Jason R.

NASA Technical Reports Server

Page 1May 6, 2009
Reefing of Quarter Spherical Ribbon Parachutes used 
in the Ares I First Stage Deceleration Subsystem
Jason Schmidt
United Space Alliance, LLC
Cape Canaveral, FL 32920
May 6, 2009
20th AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar
https://ntrs.nasa.gov/search.jsp?R=20090023552 2019-08-30T07:15:48+00:00Z
Page 2May 6, 2009
Agenda
• Introduction
• Ares I Parachutes
• Reefing Ratio Development
• Conclusion
• Acknowledgments
Objectives
• Introduce the Ares I First Stage parachutes
• Discuss reefing quarter spherical parachutes compared to literature
• Identify superior suspension line length drag area normalization curve
Page 3May 6, 2009
Ares I Program
• NASA Constellation Program
– Ares I man-rated rocket
• First stage is a reusable solid rocket booster (Space Shuttle 
variant)
• Second stage is an expendable liquid rocket (Apollo variant)
– Ares V unmanned, heavy-lift rocket
• Uses 2 solid rocket boosters, similar to Ares I first stage
• Currently developing parachutes to recover the first stage of the Ares I 
Rocket
– Similar to Space Shuttle Solid Rocket Booster (SRB) recovery 
system
– Pilot parachute, drogue parachute with reefed stages, 3 main 
parachute cluster with reefed stages
• Baseline: quarter spherical ribbon parachutes
Page 4May 6, 2009
Ares I Parachutes - Pilot
Pilot Parachute Properties: 
• Nominal diameter of 11.5 ft
• Geometric porosity of 19.5%
• Kevlar structural members, nylon ribbons
• Vent hoop construction
Currently Planned Ares I Flight Configuration: 
• Permanently reefed to near full open for Ares I
Successfully Completed Drop Tests: 
• Pilot Parachute Drop Test (PDT)-1
• PDT-2
• PDT-3R
• Drogue Parachute Drop Test (DDT)-1
• DDT-2 (two; separate programmer and pilot)
Page 5May 6, 2009
Ares I Parachutes - Drogue
Drogue Parachute Properties: 
• Nominal diameter of 68 ft
• Geometric porosity of 19.5%
• Kevlar structural members, nylon ribbons
• Double vent hoop construction
Currently Planned Ares I Flight Configuration: 
• First stage reefed to near 40% drag area
• Second stage reefed to near 60% drag area
• Third stage reefed to near 80% drag area
Successfully Completed Drop Tests: 
• DDT-1
• DDT-2, additional fullness added to vent region
Page 6May 6, 2009
Ares I Parachutes - Main
Main Parachute Properties: 
• Nominal diameter of 150 ft
• Geometric porosity of 11.5%
• Kevlar structural members, nylon ribbons
• Double vent hoop construction
Currently Planned Ares I Flight Configuration: 
• First stage reefed to near 20% drag area
• Second stage reefed to near 40% drag area
Successfully Completed Drop Tests: 
• Main Parachute Drop Test (MDT) -1 (tub)
• MDT-2 (tub)
• DDT-1
• DDT-2, porosity changed to 15.0%
Page 7May 6, 2009
Ares I Parachute Drop Test Summary
Measured Reefed Drag Areas (not normalized to Le/D)
Page 8May 6, 2009
Reefing Ribbon Parachutes
• Information on quarter spherical parachutes difficult to obtain
• Knacke published reefing line curves for flat circular and conical 
ribbon parachutes
• Required to normalize parachute data to compare to literature
– Knacke published normalization curves for ribbon parachutes
• Initially, Space Shuttle Solid Rocket Booster (SRB) and Ares I First 
Stage Parachutes did not lie on this line
• Normalizations of every kind investigated
– Primary normalization is to suspension line length
– Wolf provided additional suspension line normalization curve
Page 9May 6, 2009
Effective Reefing Line Length
• This correction is specific to Ares I parachute 
design
• CANO is used to help predict suspension line 
angles
Page 10May 6, 2009
Nominal Diameter
• Nominal diameter used in
– Reefing ratio definition
– Suspension line length normalization
• In general, actual nominal diameter is not an important parameter to 
identify
• Larger effect possible in SRB parachutes when drag areas were 
investigated after years of flight.  
– Frequent washing and drying may shrink parachutes – full open 
drag area is reduced
– New reefing lines each flight maintain reefed stage drag area
Page 11May 6, 2009
Effective Suspension Line Length
• The closer to parallel the suspension 
lines are, the lower the inboard force 
on the canopy skirt
• A reduction of inboard force at the 
canopy allows the parachute to 
inflate to a greater diameter
• Suspension lines may not converge 
to a point
• These suspension lines appear to 
the skirt of the canopy to be longer
• This effective length, Le, is obtained
Page 12May 6, 2009
Effective Suspension Line Length
Wolf and Croll, “Wind Tunnel Measurements of Dynamic Reefing Line Force 
in Ribbon Parachutes” J. Aircraft, Vol. 18, No. 1, 1981.
• Curves exist for determining the 
additional drag produced by 
longer suspension lines 
• The Parachute Recovery 
Systems Design Manual 
(Knacke) provides a 
normalization
• Wolf and Croll provide a similar 
curve, but for ribbon parachutes 
of different porosities
• These two curves disagree
• When Ares I and SRB data are 
normalized with the Wolf curve, 
the reefing ratios match the 
drag areas predicted in the 
Parachute Recovery Systems 
Design Manual
Page 13May 6, 2009
Ares I Drop Test Results – Normalized to Le/D = 1
PDT-3R
PDT-2
PDT-1
MDT-2
MDT-1
DDT-1
Page 14May 6, 2009
Conclusions
• Normalizing drop test reefed drag area for suspension line length with 
data from Wolf allows best match of test results with Knacke reefing 
ratio curve
• Various sizes and porosities of quarter spherical ribbon parachutes 
were tested
• All appear to fit the published reefing ratio curve – quarter spherical 
parachutes match 
Page 15May 6, 2009
Acknowledgments
• Peter McFadden – my mentor over the past 3 years, co-author on paper
• Dr. Dean Wolf – wealth of information, provided team guidance through 
development and testing of Ares I parachutes
• Ares I Deceleration Subsystem Team
– MSFC NASA, ATK, USA, Pioneer, L3 Coleman, YPG


Reefing of Quarter Spherical Ribbon Parachutes used in the Ares I First Stage Deceleration Subsystem

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server