SpaceX F9 : Transporter-4 Rideshare : CCSFS SLC-40 : 1 April 2022 (16:24 UTC)

[OneSpeed]

Here is a comparison between the webcast telemetry from the Transporter 1 and 4 missions.

Some of the differences are:

1. The T-4 throttle bucket occurred some 6 seconds earlier, with a flat bottom rather than a vee shape.

2. Although from the plot it looks like the T-4 second stage took longer to ignite, this is just an artefact caused by the delay in S2 data appearing on screen.

3. The T-4 S2 throttled back considerably from around the 385s mark, on it's way to a much higher injection altitude of 649km vs the 226km of T-1.

4. The "Starlink Mission Control Audio" video has unfortunately been marked private, but there is still enough coverage of the ground track in the mission webcast to judge the orbital inclination from the pass over Antarctica. The furthest south latitude reached over the Ross Ice Shelf is about 81.5° S, corresponding to a retrograde inclination of about 98.5°.

[alugobi]

Booster topped out about 100 km higher than on a typical Starlink launch.

[Rondaz]

CelesTrak now has post-deployment SupTLEs for 20 objects from the #Transporter-4 launch based on updated state vectors from
@SpaceX:

https://twitter.com/TSKelso/status/1509996047036129280

[RocketLover0119]

NSF stream grabs of launch. Went from ground into the clouds in about 25 seconds.

[Comga]

CelesTrak now has post-deployment SupTLEs for 20 objects from the #Transporter-4 launch based on updated state vectors from @SpaceX:

https://twitter.com/TSKelso/status/1509996047036129280

So Transporter 4 direct injected into a nearly circular orbit of 492 by 510 km, then used two burns to raise the orbit by ~100 km and do a slight plane change.

[LouScheffer]

Here is a comparison between the webcast telemetry from the Transporter 1 and 4 missions.

Some of the differences are:

1. The T-4 throttle bucket occurred some 6 seconds earlier, with a flat bottom rather than a vee shape.

2. Although from the plot it looks like the T-4 second stage took longer to ignite, this is just an artefact caused by the delay in S2 data appearing on screen.

The trajectory looks much more lofted than the previous mission.  You can tell from the (negative) acceleration during staging.  We know this is -1G from physics, but the amount of this we see ranges from -1G (if the rocket went straight up) to 0G, if it's on the horizon. So this rocket was at a higher angle from the launch pad at MECO.  This more lofted trajectory also explains why the Max-Q throttle bucket is earlier.

[scr00chy]

So Transporter 4 direct injected into a nearly circular orbit of 492 by 510 km, then used two burns to raise the orbit by ~100 km and do a slight plane change.

The opposite. The first three satellite were deployed at around 650 km x 640 km x 97.95° and then the two burns changed the orbit to approx. 510 km x 500 km x 97.39°.

[gongora]

Booster topped out about 100 km higher than on a typical Starlink launch.

More like 350km higher than a typical Starlink launch.

[OneSpeed]

The trajectory looks much more lofted than the previous mission.  You can tell from the (negative) acceleration during staging.  We know this is -1G from physics, but the amount of this we see ranges from -1G (if the rocket went straight up) to 0G, if it's on the horizon. So this rocket was at a higher angle from the launch pad at MECO.  This more lofted trajectory also explains why the Max-Q throttle bucket is earlier.

Yes, T-4 clearly has more loft, but the altitudes and velocities don't meaningfully diverge until around T+02:00, well after Max-Q.

T-1 throttled back at 263m/s and 5.3km altitude, and reached full throttle again at 323m/s and 8.1km, just supersonic.
T-4 throttled back at 220m/s and 4.0km altitude, and reached full throttle again at 288m/s and 7.2km, well below supersonic.

I can't see how these variations are related to differences in loft, which is much the same up to this point. Perhaps the cloud layers were a factor?

[Chinakpradhan]

https://mobile.twitter.com/tobyliiiiiiiiii/status/1509928631811731457 really new intro

[alugobi]

Stage 1 reached 233km and then descended to land. Most Starlink boosters top out at about 130-some.

[LouScheffer]

The trajectory looks much more lofted than the previous mission.  You can tell from the (negative) acceleration during staging.  We know this is -1G from physics, but the amount of this we see ranges from -1G (if the rocket went straight up) to 0G, if it's on the horizon. So this rocket was at a higher angle from the launch pad at MECO.  This more lofted trajectory also explains why the Max-Q throttle bucket is earlier.

Yes, T-4 clearly has more loft, but the altitudes and velocities don't meaningfully diverge until around T+02:00, well after Max-Q.

T-1 throttled back at 263m/s and 5.3km altitude, and reached full throttle again at 323m/s and 8.1km, just supersonic.
T-4 throttled back at 220m/s and 4.0km altitude, and reached full throttle again at 288m/s and 7.2km, well below supersonic.

I can't see how these variations are related to differences in loft, which is much the same up to this point. Perhaps the cloud layers were a factor?

A super-crude approximation says max-q is earlier for higher loft.  Consider a rocket with acceleration a, launched at angle theta to the horizon, in an atmosphere with density scale 8500 m.  What's the q (proportional to density and v^2) at height h?

The distance traveled, s = h/sin(theta).  Since v=sqrt(2*a*s) , v^2 = 2*a*h/sin(theta).  So now q ~ e^(-h/8500) * 2*a*h/sin(theta).

We differentiate this with respect to h, and set to 0.  The acceleration and theta are just constants and drop out, and the max will be when the derivative of h*exp(-h/8500) = 0.  This always happens at height 8500m.

So to very, very first order, the rocket always reaches max q at the same altitude. But the time to reach this altitude will be less when the loft is greater, since the rocket has less distance to travel.

Now this is a super-simple model, neglecting gravity losses, increasing acceleration as fuel is used, etc.  But I'd be surprised if the basics did not hold - max-q is at a similar altitude, and more lofted launches reach max-q faster.

[Rondaz]

JRTI droneship has already departed the Transporter-4 LZ and is en-route to Port Canaveral.

Bob is also alongside but might breakaway and arrive sooner. ETAs later today.

https://twitter.com/SpaceOffshore/status/1510263955385683970

[Bean Kenobi]

Missing satellite, undisclosed, is Tiger 3, see right picture.

https://twitter.com/NanoAvionics/status/1509926753829019652?ref_src=twsrc%5Etfw%7Ctwcamp%5Etweetembed%7Ctwterm%5E1509926753829019652%7Ctwgr%5E%7Ctwcon%5Es1_&ref_url=https%3A%2F%2Fforum.nasaspaceflight.com%2Findex.php%3Ftopic%3D54106.100

[gongora]

Missing satellite, undisclosed, is Tiger 3

Tiger 3 is a payload on a shared satellite

[Bean Kenobi]

You're right, the 40th one is the 3rd Nanoavionics cubesat for "undisclosed customer" (on the left picture).

[Rondaz]

Bob and the Transporter-4 fairing halves should arrive around 7am ET on Sunday.

JRTI and the booster should return Sunday evening or Monday morning.

https://twitter.com/SpaceOffshore/status/1510405529197334531

[Chinakpradhan]

https://idrw.org/spacexs-transporter-4-launches-td-2-made-by-indian-start-up-pixxel/

[scr00chy]

Both fairing halves were successfully recovered by Bob

https://twitter.com/astrogeo/status/1510653473842515973

[Rondaz]

Bob closing in on the port. @SpaceOffshore If you zoom in, you can see Maverick hanging off the side!

https://twitter.com/JerryPikePhoto/status/1510641692369723397