Introduction to Parachute Systems

Components of a Parachute System Canopy: the major drag producing member of the parachute Vent: very upper region of the canopy, open to airflow Suspension Lines: load bearing members extending from the canopy to the payload Radials: load bearing member running from the suspension lines at the skirt to the vent lines Gore: section of a parachute canopy between two radials Behr, V. and Potvin, J., “Parachute Definitions, Nomenclature and Types,” H.G. Heinrich Parachute Systems Short Course, 15-19 May 2006. Space Systems Engineering

Components of a Parachute System Pilot Parachute: a small parachute which is attached to a deployment bag or the vent of a larger parachute and is used to provide the force required to deploy a larger parachute. Mars Pathfinder Drop Test Drogue Parachute: a parachute which is attached to the payload and is used to provide stabilization or initial deceleration or both. Usually implies a larger parachute will be deployed later in the event sequence. Frequently used as the pilot parachute for the main parachute. canopy suspension lines riser backshell Riser: a line connecting a parachute to its payload. May utilize a single or multi-point attachment scheme. bridle Bridle: a means of providing a multi-point connection to a deployment bag or a vehicle from a parachute or riser. MPF lander Witkowski, A., “Mars Pathfinder Parachute System Performance,” AIAA 99-1701. Space Systems Engineering

Components of a Parachute System Behr, V. and Potvin, J., “Parachute Definitions, Nomenclature and Types,” H.G. Heinrich Parachute Systems Short Course, 15-19 May 2006. Cruz, J.R., “Parachutes for Planetary Entry Systems,” AE8803 / Planetary Entry, Georgia Institute of Technology, Spring 2007. Deployment Bag: a textile container for a parachute from which the parachute deploys. It’s main purpose is to effect an organized deployment Space Systems Engineering

Components of a Parachute System Mortar: a deployment device used to eject a packed parachute from the payload as one mass to begin the deployment process. Mortars are the most common method of parachute deployment for spacecraft planetary entry. Example: Mortar Assembly for the Apollo Drogue Chute Knacke, T.W., Parachute Recovery Systems Design Manual, Para Publishing, 1992. Space Systems Engineering

Typical Parachute Deployment Sequence Example from Mars Pathfinder Cruz, J.R., “Parachutes for Planetary Entry Systems,” AE8803 / Planetary Entry, Georgia Institute of Technology, Spring 2007. Knacke, T.W., Parachute Recovery Systems Design Manual, Para Publishing, 1992. Space Systems Engineering

Common Type of Parachutes & Their Uses Disk-Gap-Band (DGB) Ringsail Ribbon Example spacecraft uses: Viking Landers Mars Pathfinder Mars Exploration Rovers Mars Phoenix Huygens Example spacecraft uses: Mercury main chutes Gemini main chutes Apollo CM main chutes Example spacecraft uses: Pioneer Venus Galileo Mercury drogue chutes Gemini drogue chutes Apollo CM drogue chutes Space Shuttle SRB chutes Image from Mercury program Image from MER wind tunnel test Image from Galileo wind tunnel test Cruz, J.R., “Parachutes for Planetary Entry Systems,” AE8803 / Planetary Entry, Georgia Institute of Technology, Spring 2007. http:// history.nasa.gov/SP-4001/images/fig18.jpg http://solarsystem.nasa.gov/multimedia/gallery/ Galileo_WindTest.jpg Space Systems Engineering

Successful Parachute Deployment Here are two videos that demonstrate successful parachute in a spacecraft related context: Successful drop test from NASA Supersonic Planetary Entry Decelerator Program, SPED-1 (we’ll see some unsuccessful tests from this program a little later) (LV-2007-00059) Space Shuttle Solid Rocket Booster (SRB) parachute deployment Space Systems Engineering

Potential Failures (a partial list) There are many things that can lead to a parachute system failure. To help you gain a feel for the types of failure that may occur, let’s look at the following potential failure modes: Mortar doesn’t fire Aerodynamic loads exceed design Suspension lines become twisted or tangled Recontact with reentry and/or parachute hardware “Dumping” the canopy Asynchronous inflation of parachute clusters Squidding Wake recontact And many more… Example: Genesis Earth entry Space Systems Engineering

Space Systems Engineering Genesis Failure When the Genesis spacecraft returned to Earth on September 8, 2004, the parachutes failed to deploy. The spacecraft plunged into the Utah desert at 200 mph and broke apart. The redundant sets of switches controlling parachute deployment failed to respond to reentry deceleration because both sets were installed backwards as specified in the Lockheed-Martin design. http://www.youtube.com/watch?v=e875O0hSces Text and images from the Design Fundamentals Lecture by L. Guerra Space Systems Engineering

Potential Failures (a partial list) There are many things that can lead to a parachute system failure. To help you gain a feel for the types of failure that may occur, let’s look at the following potential failure modes: Mortar doesn’t fire Aerodynamic loads exceed design Suspension lines become twisted or tangled Recontact with reentry and/or parachute hardware “Dumping” the canopy Asynchronous inflation of parachute clusters Squidding Wake recontact And many more… Example: Drop test. After 1.07 seconds of operation, a large tear appeared in the cloth near the canopy apex. This tear was followed by two additional tears shortly thereafter. As a result of the damage to the disk area of the canopy, the parachute performance was significantly reduced; however, the parachute remained operationally intact throughout the flight test and the instrumented payload was recovered undamaged. (LV-2007-00064) Space Systems Engineering

Potential Failures (a partial list) There are many things that can lead to a parachute system failure. To help you gain a feel for the types of failure that may occur, let’s look at the following potential failure modes: Mortar doesn’t fire Aerodynamic loads exceed design Suspension lines become twisted or tangled Recontact with reentry and/or parachute hardware “Dumping” the canopy Asynchronous inflation of parachute clusters Squidding Wake recontact And many more… Example: Drop test. Parachute suspension lines get twisted because the partially inflated canopy could not restrict the twisting to the attachment bridle and risers. (LV-2007-00052) Space Systems Engineering

Potential Failures (a partial list) There are many things that can lead to a parachute system failure. To help you gain a feel for the types of failure that may occur, let’s look at the following potential failure modes: Mortar doesn’t fire Aerodynamic loads exceed design Suspension lines become twisted or tangled Recontact with reentry and/or parachute hardware “Dumping” the canopy Asynchronous inflation of parachute clusters Squidding Wake recontact And many more… Example: a. Drop test. One gore of the test parachute was damaged when the deployment bag with mortar lid passed through it from behind approximately 2 seconds after deployment was initiated. (LV-2007-00061) b. Apollo 15 Space Systems Engineering

Apollo 15 Main Parachute System Failure All three main parachutes deployed without incident at an altitude of 10,000 ft One of the three parachutes deflated while the Apollo 15 capsule was obscured by clouds between 7,000 ft and 6,000 ft According to the “Apollo 15 Main Parachute Failure Anomaly Report No. 1” (NASA-TM-X-6835): “The most probably cause of the anomaly was the burning of raw fuel (monomethyl hydrazine) being expelled during the latter portion of the depletion firing and this resulted in exceeding the parachute-riser and suspension-line temperature limits.” http://www.hq.nasa.gov/office/pao/History/alsj/a15/ap15-S71-42217HR.jpg Space Systems Engineering

Potential Failures (a partial list) There are many things that can lead to a parachute system failure. To help you gain a feel for the types of failure that may occur, let’s look at the following potential failure modes: Mortar doesn’t fire Aerodynamic loads exceed design Suspension lines become twisted or tangled Recontact with reentry and/or parachute hardware “Dumping” the canopy Asynchronous inflation of parachute clusters Squidding Wake recontact And many more… Space Systems Engineering

Example of Wake Recontact Behr, V. and Potvin, J., “Parachute Definitions, Nomenclature and Types,” H.G. Heinrich Parachute Systems Short Course, 15-19 May 2006. Space Systems Engineering