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WooHoo

Apollo Landings back to earth

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I was watching a documentary about he Apollo space programme and their journey to orbit, then subsequently land on the moon.

I was interested to find out more about their parachute system, as a skydiver I am very familiar with the implications of two-out situation, or a reserve main entanglement. The film showed the Apollo capsule under thre large round parachutes, I am just curious how these are deployed to avoid an entanglement.

Are they staggered? Just curious. Plus the packing, How much would a packer get for doing all three? .....:o)

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In 1993 the PIA Parachute Symposium included a tour of the space shuttle solid rocket booster parachute recovery facility and Kennedy Space Center. When they recoved at sea the solid rocket boosters the paracutes, also 3 per booster IIRC, are wound onto large spools and kept wet during transport to the facility. The parachtues are unwound and hung onto a large overhead 'meat hook' type trolley system. This is all done under water spray to again keep them from drying while soaked in sea water. This over head system allows the parachutes to be moved into a washing machine. A long narrow fiberglass or similar material room. It's sealed and the parachute is washed and rinsed. Then it is moved, again all on the over head system to a drying 'room'. The canopys are ribbon canopies and require over a hundred repairs after each use. Mainly holes from burning slag from the boosters. They are essentially packed like any other round. They have pyrotechnic cutters that effect staging of the opening. A large pilot chute extracts an even larger drogue (20, 30, 40' diameter) when then acts as PC for the mains. Seems like over a 100' diameter. These are packed using a hydrolic ram into a three bay compartment. Seems like the entire parachute assembly packed was maybe 5' high and 5' wide and cone shaped. Lots of d bags tied shut.

I have photos of most of this and a flyer explaining a lot of it somewhere at home. All of the above was from my failing memory.

Hmmm had some sizes wrong.

"The recovery sequence begins with the operation of the high-altitude baroswitch, which triggers the pyrotechnic nose cap thrusters. This ejects the nose cap, which deploys the pilot parachute. Nose cap separation occurs at a nominal altitude of 15,704 feet (4,787 m) about 218 seconds after SRB separation. The 11.5-foot (3.5 m) diameter conical ribbon pilot parachute provides the force to pull lanyards attached to cut knives, which cut the loop securing the drogue retention straps. This allows the pilot chute to pull the drogue pack from the SRB, causing the drogue suspension lines to deploy from their stored position. At full extension of the twelve 105-foot (32 m) suspension lines, the drogue deployment bag is stripped away from the canopy, and the 54-foot (16 m) diameter conical ribbon drogue parachute inflates to its initial reefed condition. The drogue disreefs twice after specified time delays (using redundant 7 and 12-second reefing line cutters), and it reorients/stabilizes the SRB for main chute deployment. The drogue parachute has a design load of approximately 315,000 pounds (143,000 kg) and weighs approximately 1,200 pounds (544 kg).

After the drogue chute has stabilized the SRB in a tail-first attitude, the frustum is separated from the forward skirt by a pyrotechnic charge triggered by the low-altitude baroswitch at a nominal altitude of 5,500 feet (1,676 m) about 243 seconds after SRB separation. The frustum is then pulled away from the SRB by the drogue chute. The main chute suspension lines are pulled out from deployment bags that remain in the frustum. At full extension of the lines, which are 203 feet (62 m) long, the three main chutes are pulled from their deployment bags and inflate to their first reefed condition. The frustum and drogue parachute continue on a separate trajectory to splashdown. After specified time delays (using redundant 10 and 17-second reefing line cutters), the main chute reefing lines are cut and the chutes inflate to their second reefed and full open configurations. The main chute cluster decelerates the SRB to terminal conditions. Each of the 136-foot (41 m) diameter, 20-degree conical ribbon parachutes have a design load of approximately 195,000 pounds (88,500 kg) and each weighs approximately 2,180 pounds (989 kg). These chutes are the largest that have ever been used--both in deployed size and load weight. The RSRM nozzle extension is severed by a pyrotechnic charge about 20 seconds after frustum separation."
I'm old for my age.
Terry Urban
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Two-out is refered with 2 square canopy. You may deploy a cluster of round canopies.....

I had some round jumps. There was no cut-away in EP.


Actually, there commonly was a cutaway involved after the mid-70's. And having two out wasn't as desirable as having a single canopy, because you couldn't control the direction and forward speed (negligible though they may be) as well.

Clusters are most commonly used when the canopies are identically sized and not steerable, as is the case for the Apollo capsule (and all of the Russian ones, I'm sure). Smaller canopies deploy more easily than a single big gigantic canopy, and a malfunction isn't necessarily quite as harmful.

And, well, no one cares if the space capsule stomps the disk. "Accuracy" is landing within a few miles of where you wanted to.

Wendy W.
There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

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>The film showed the Apollo capsule under thre large round parachutes,
>I am just curious how these are deployed to avoid an entanglement.

As far as I know they all deploy at once. Rounds are unlike squares in that they WANT to separate a bit, but then stay above the payload. Has to do with the air spilling from beneath them; that creates a higher pressure around the skirt. That's why the parachutes don't seem to be touching as the CM descends.

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Apollo 15 even had a malfunciton.

[The state of the three chutes is well shown in S71-41999, an excellent photograph of the returning spacecraft.]

[From the Apollo 15 Postflight Mission Report - "One of the three main parachutes was deflated to approximately one fifth of its full diameter at about 6,000 feet [about 1,800 meters] altitude. The Command Module descended in this configuration to landing. All three parachutes were disconnected and one good main parachute was recovered. Photographs of the descending spacecraft indicate that two or three of the six riser legs on the failed parachute were missing.

Three areas that were considered as possible causes are:

a. The forward heat shield, which was in close proximity to the spacecraft flight path.

b. A broken riser/suspension line connector link which was found on the recovered parachute.

c. The Command Module Reaction Control System propellant firing and fuel dump.

Onboard and photographic data indicate that the forward heat shield - was about 720 feet (220 metres) below the spacecraft at the time of the failure. The failed link on the recovered parachute implies the possibility of a similar occurrence on the failed parachute. Based on parachute tow tests, however, more than one link would have had to fail to duplicate the flight problem. The two possible causes have been identified as hydrogen embrittlement or stress corrosion."]

["The Command Module Reaction Control System depletion firing was considered as a possible candidate because of the known susceptibility of the parachute material (nylon) to damage from the oxidizer. Also because the oxidizer depletion occurred about 3 seconds prior to the anomaly, and fuel was being expelled at the time the anomaly occurred. Further, the orientation of the main parachutes over the command module placed the failed parachute in close proximity to the Reaction Control System roll engines. Testing of a Command Module Reaction Control System engine simulating the fuel (monomethyl hydrazine) dump mode through a hot engine resulted in the fuel burning profusely; therefore, the fuel dump is considered to be the most likely cause of the anomaly."]

["In order to eliminate critical processing operations from manufacture of the connector links, the material was changed from 4130 to Inconel 718."]

["Based on the low probability of contact and the minimum damage anticipated should contact occur, no corrective action will be implemented for the forward heat shield. Corrective actions for the Reaction Control System include landing with the propellants onboard for a normal landing, and biasing the propellant load to provide a slight excess of oxidizer. Thus, for low altitude abort land landing case, burning the propellants while on the parachutes will subject the parachutes to some acceptable oxidizer damage but, will eliminate the dangerous fuel burning condition. In addition, the time delay which inhibits the rapid propellant dump may be changed from 42 to 61 seconds. This could provide more assurance that the propellant will not have to be burned through the Reaction Control System engines in the event of a land landing. A detailed discussion of all analyses and tests is contained in a separate anomaly report."]

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7740 pounds of canopies, at $10000 a pound to launch it,... $77,400,000.00 per booster?

over 150 million dollars just to launch the canopies? :o that has to be wrong. [unsure]

"Hang on a sec, the young'uns are throwin' beer cans at a golf cart."
MB4252 TDS699
killing threads since 2001

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7740 pounds of canopies, at $10000 a pound to launch it,... $77,400,000.00 per booster?

over 150 million dollars just to launch the canopies? :o that has to be wrong. [unsure]



That figure for $/lb to launch is all the way to orbit. The boosters and the canopies don't make it to orbit will be much lower. Still a mind boggling figure but not the $150 million.
Scars remind us that the past is real

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7740 pounds of canopies, at $10000 a pound to launch it,... $77,400,000.00 per booster?

over 150 million dollars just to launch the canopies? :o that has to be wrong. [unsure]



That figure for $/lb to launch is all the way to orbit. The boosters and the canopies don't make it to orbit will be much lower. Still a mind boggling figure but not the $150 million.


Whatdaya mean...it's taxpayer money...so it's FREE! :ph34r:










~ If you choke a Smurf, what color does it turn? ~

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7740 pounds of canopies, at $10000 a pound to launch it,... $77,400,000.00 per booster?

over 150 million dollars just to launch the canopies? :o that has to be wrong. [unsure]



if you are on the ground then it seems like too much, if you are in the capsule it is worth every penny :)
Give one city to the thugs so they can all live together. I vote for Chicago where they have strict gun laws.

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Maybe they should have just invented a 4,000Sq foot Ram Air canopy



Already done..how about a 7500ft^2 parafoil...http://kjeldvandruten.3sc.nl/x38.html

x38 results and info on large parafoil applications...http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070026249_2007023714.pdf


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councilman24.......the space shuttle solid rocket booster parachute recovery



srb video, canopy deployment @ 02:43 http://www.youtube.com/watch?v=LhnU3KB_fi0&feature=related


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Apollo 15 even had a malfunciton.



I believe they only needed two canopies, but used three for this reason.....
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Three areas that were considered as possible causes are:

a. The forward heat shield, which was in close proximity to the spacecraft flight path



They also used a mortar system to deploy two drogues, due to possible contact with the heat shield, and for the same reasons some people put 2 MA1s in a rig

Details can be found here, page five discusses recovery....http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730062665_1973062665.pdf

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