Quote from: Jim on 01/25/2018 03:38 pmQuote from: Rocket Science on 01/25/2018 03:25 pmIIRC the rain bird sound suppression system was mainly for potential acoustic damage the the Shuttle's tiles and during Apollo water was mainly for cooling...For Shuttle, it was the payloadsYou are both wrong in that you are both only one-third right. The substantial beefing-up of the sound suppression system after STS-1 was due to:1. Reported damage to the orbiter and anomalies (body flap structural deflection, airframe cracks, tiles [16 lost, 148 damaged], forward RCS strut buckling) from SRB ignition over-pressure.2. Concern for the payloads (courtesy of data coming from the DFI payload)3. Reported damage to the mobile launcher (9.1 meter long crack in upper deck due to shuttle drift over the platform with insufficient shielding from SRB accoustics).All this information is readily available from NASA and other public source.
Quote from: Rocket Science on 01/25/2018 03:25 pmIIRC the rain bird sound suppression system was mainly for potential acoustic damage the the Shuttle's tiles and during Apollo water was mainly for cooling...For Shuttle, it was the payloads
IIRC the rain bird sound suppression system was mainly for potential acoustic damage the the Shuttle's tiles and during Apollo water was mainly for cooling...
Quote from: Shanuson on 01/26/2018 06:46 amQuote from: Lars-J on 01/26/2018 06:11 amNot the torque issue again... Please watch the last 40 or so F9 flights and see what kind of torque induced rotation you see when the hold-downs release. (hint: none)I thought its about spin up of the turbo pumps, which is done while the rocket is still hold down (to abort if something goes wrong during this spin up / engine startup). This torque is absorbed by the hold-downs and short lived (lot less than 1sec). So at the moment of release of the hold-downs (>2s after startup) there is not torque anymore to rotate the rocket and you see like you said nothing.I recall that the first F9 launch exhibited a great deal of rotation directly off the pad. To what cause was this attributed?
Quote from: Lars-J on 01/26/2018 06:11 amNot the torque issue again... Please watch the last 40 or so F9 flights and see what kind of torque induced rotation you see when the hold-downs release. (hint: none)I thought its about spin up of the turbo pumps, which is done while the rocket is still hold down (to abort if something goes wrong during this spin up / engine startup). This torque is absorbed by the hold-downs and short lived (lot less than 1sec). So at the moment of release of the hold-downs (>2s after startup) there is not torque anymore to rotate the rocket and you see like you said nothing.
Not the torque issue again... Please watch the last 40 or so F9 flights and see what kind of torque induced rotation you see when the hold-downs release. (hint: none)
AFAIK it was rotational torque from engine startup, exactly as described. they fixed it by pre-canting the engines to counter the torque on the next flight (or, more likely correcting the angle from the predicted roll to the measured roll).
Quote from: starsilk on 01/26/2018 03:14 pmAFAIK it was rotational torque from engine startup, exactly as described. they fixed it by pre-canting the engines to counter the torque on the next flight (or, more likely correcting the angle from the predicted roll to the measured roll).Do you have a source for this - it seems extraordinarily unlikely that anything other than an INS issue could cause an uncommanded and uncorrected roll and not result in loss of mission.
Quote from: Lars-J on 01/26/2018 06:11 amNot the torque issue again... Please watch the last 40 or so F9 flights and see what kind of torque induced rotation you see when the hold-downs release. (hint: none) I'm pretty sure the rocket wouldn't be released until the engines were going. The whole issue is with startup you know.
My reaction is more to the "OMG SpaceX might have completely forgotten about startup torque for FH!!!" type of posts. Please - can we at least assume that SpaceX has some degree of competency here?
Quote from: woods170 on 01/26/2018 06:38 amQuote from: Jim on 01/25/2018 03:38 pmQuote from: Rocket Science on 01/25/2018 03:25 pmIIRC the rain bird sound suppression system was mainly for potential acoustic damage the the Shuttle's tiles and during Apollo water was mainly for cooling...For Shuttle, it was the payloadsYou are both wrong in that you are both only one-third right. The substantial beefing-up of the sound suppression system after STS-1 was due to:1. Reported damage to the orbiter and anomalies (body flap structural deflection, airframe cracks, tiles [16 lost, 148 damaged], forward RCS strut buckling) from SRB ignition over-pressure.2. Concern for the payloads (courtesy of data coming from the DFI payload)3. Reported damage to the mobile launcher (9.1 meter long crack in upper deck due to shuttle drift over the platform with insufficient shielding from SRB accoustics).All this information is readily available from NASA and other public source.The primary purpose that sound suppression existed in the first place (before the first launch) was to protect the payloads. The 6 rainbirds were installed on the deck of the MLP to blanket the deck with a layer of water. This was to prevent reflection of sound from the large deck when the vehicle was a few seconds off the pad. The side mounting location of the orbiter and the payload bay put the payloads in a more vulnerable position to this reflected sound. Water bags and additional nozzles in the flame ducts for SRB ignition overpressure were added after the first flight.
Launch date, per the current plan:NET Feb 6th with backup on the 7th.Launch window each day is 13:30-16:30 EST.