Apollo Capsule Boost Protect Shield?

I was just looking at the Apogee website, at the Apollo capsule kit (here), and saw that they referred to it as also being known as the "boost protect shield." I had never heard of this, so I looked it up.
This search led me to this early illustration:

So, my question is, was there really a cone-shaped shield that went over the entire CM and was jettisoned it orbit along with the LES? Or was this just a concept drawing that was never used on the spacecraft?
It would certainly explain why all the pictures of Saturn Vs sitting on the pad show the CM being white, and all the pictures of the spacecraft orbiting the moon show the CM being silver...

Thanks!

Rocketbuilder said:

I was just looking at the Apogee website, at the Apollo capsule kit (here), and saw that they referred to it as also being known as the "boost protect shield." I had never heard of this, so I looked it up.
This search led me to this early illustration:
View attachment 89296
So, my question is, was there really a cone-shaped shield that went over the entire CM and was jettisoned it orbit along with the LES? Or was this just a concept drawing that was never used on the spacecraft?
It would certainly explain why all the pictures of Saturn Vs sitting on the pad show the CM being white, and all the pictures of the spacecraft orbiting the moon show the CM being silver...

Thanks!

Click to expand...

Yes this is quite true... The BPC (Boost Protection Cover) was designed for two reasons. First, the CM was covered with highly reflective mylar (mirrored/chrome looking) to reflect solar heat in space to assist with temperature control (on the lunar versions anyway-- the later Skylab long-duration Low Earth Orbit (LEO) versions were half white (on one side) and half mylar (on the other) due to the different thermal environment in LEO (from having a huge honkin' infrared (heat) radiating planet below). This mylar could be damaged by the force of the slipstream of air tearing past the rocket as it ascended through Earth's atmosphere. The second purpose was that the LES motor (Launch Escape System) when fired produced a significant blast of gases and heat and the BPC helped protect the capsule from this searing heat, blast, and debris. The final reason was to provide thermal protection on ascent for the CM and its coating and systems near the nosecone, like the docking system and parachute canisters. The BPC was covered with insulating cork to provide heat protection from aerodynamic heating from air friction drag on the rocket during ascent. The space shuttle ET got up to 400 degrees or so on its nose area and in the area of the shock wave impingement on the tank walls on either side of and slightly below the SRB nose cones and under the orbiter nosecap from aerodynamic heating in flight... the Apollo would have gotten similarly hot (though I don't recall the exact temperatures). These high temps would have been very hard on the mylar coating and the exposed systems on the front area of the capsule, naturally.

Also, the BPC was attached to the legs of the LES tower, which held up the LES motor(s) (which consisted of two main solid rocket motors-- the actual LES abort motor, and an LES tower jettison motor of much less power, which fired through two scarfed (flush tapered) nozzles about halfway up the tower rocket cylinder-- the abort motor was MUCH bigger and fired through the 4 canted nozzles at the base of the tower motor cylinder. There were also some steering motors (IIRC) and some fold-out canards which would deploy in an actual abort). The LES tower would NOT be carried all the way to orbit... it was a HUGE weight and thus subtracted from the rocket's payload capacity... to minimize this deleterious impact, the LES tower was jettisoned as soon in the flight profile as was possible. This occurred shortly after second stage ignition, at which point the separation bolts holding the LES tower, rocket motor cylinders, and BPC to the top of the CM would fire, and the jettison motor would ignite, pulling the motors, tower legs, and BPC away from the top of the CM. The LES tower was necessary to provide an abort capability on the launching pad, and during liftoff and ascent through the lower "sensable" atmosphere where the CSM SPS propulsion engine simply did not have enough power to lift the heavy SM and CM off the stack on the pad or early in the flight in the Earth's atmosphere. By the time of second stage ignition, the rocket was well above 99% of Earth's atmosphere (most of which lies below an altitude of 20 miles) and going at such a speed that were an abort necessary, the SPS had enough thrust to safely push the entire CSM away from the rocket stack, at which point the SM would be jettisoned and the capsule reoriented for reentry and then splashdown across the Atlantic...

Hope this clarifies it for you...
Later! OL JR

OK, a short transcript of the Apollo 11 flight goes like this,

At 3 minutes into the flight 12 seconds after second stage ignition,

All 2nd stage engines running at full thrust,
Downrange 70 miles,
Altitude 35 miles,
Velocity 9,300 fps (just under mach 9)

Jettison Tower,

Words of Neil Armstrong, "Houston, be advised visual is go today.
Yea, they finally gave me a window to look at."

The BPC covered the window.:wink:

Thanks guys. That helps a lot. This must be a little known fact, because I have never heard it mentioned anywhere else before... Or maybe I just didn't notice it.
Oh, and that makes one more thing MIB3 got wrong about Apollo. :bangpan:

View attachment 89321

Back in the archive, member Gus and I did the two pad Abort projects. Gus did Pad Abort 1 and I did Pad Abort 2.

We did a lot of research on the Apollo Capsules.

https://www.rocketryforumarchive.com/showthread.php?t=25121&highlight=Apollo

Pad Abort 1 had no BPC but Pad Abort 2 did.

The BPC is 1" thick.

Here's Gus's video.

https://www.youtube.com/watch?v=WZCSuwO_muU

This is a test of the system that was a little too real.

https://youtu.be/AqeJzItldSQ

OL JR covered it pretty well.

But, just in case you would like a little more info ... https://www.apollosaturn.com/asnr/escape.htm

Greg