Author Topic: SpaceX Falcon 9 FT - ORBCOMM-2 - Dec. 21, 2015 (Return To Flight) DISCUSSION (Read 1360602 times)

MikeAtkinson · « **Reply #1540 on:** 12/22/2015 07:34 am »

Quote from: Steven Pietrobon on 12/22/2015 07:31 am

Four cores under assembly.

I think that was old footage.

Steven Pietrobon · « **Reply #1541 on:** 12/22/2015 07:37 am »

Engine assembly area behind mission control. First flown Dragon in centre.

Dragon 2 performing Mars re-entry.

Barge area compared to LZ-1. Length is about 1 km.

Of Course I Still Love You barge.

Steven Pietrobon · « **Reply #1542 on:** 12/22/2015 07:39 am »

Strongback retract.

Closeup of strongback retraction.

MaxQ

First view of rocketcam.

Steven Pietrobon · « **Reply #1543 on:** 12/22/2015 07:42 am »

First stage cutoff.

Merlin vac engine before first stage separation.

First stage separation.

First stage is small bright area to left of nozzle reflecting light source.

Steven Pietrobon · « **Reply #1544 on:** 12/22/2015 07:49 am »

Finally get a full picture of the nozzle. You can see the light source clearly reflecting off the first stage. Can't see pusher due to angle.

Start of ignition with green tinge from ignition fluid. The first stage is still pretty close.

Full ignition. The first stage is getting a good toasting.

Separation of nozzle strengthening rings at base of nozzle. They are a lot wider than the previous rings used.

Steven Pietrobon · « **Reply #1545 on:** 12/22/2015 07:53 am »

Fairing separation.

Second stage LOX tank. Can see three Helium tanks. Not sure what the white thing is to the right. The LOX appears less blue than in previous flights, maybe because of the subcooled temperature.

Steven Pietrobon · « **Reply #1546 on:** 12/22/2015 07:55 am »

Pencil rocket Liftoff!

Stage separation.

Flip manoeuvre.

Entry burn.

Landing.

Steven Pietrobon · « **Reply #1547 on:** 12/22/2015 07:57 am »

First stage coming into land.

Above the pad.

Performing landing.

Landed!

Steven Pietrobon · « **Reply #1548 on:** 12/22/2015 08:01 am »

Closeup of stage. Fire at base.

Fire going out.

Still burning.

Top of stage.

Base. The fire looks to be out.

Antilope7724 · « **Reply #1549 on:** 12/22/2015 08:03 am »

This mission reminds me of the "all-up" flight of Apollo 4. There had been plans to test the Saturn V progressively. A mission with only stage 1 live, then a couple of live stages, working up to a fully functional test. Then they decided to go for it and use all live stages on the first mission.

This flight was kind of like that. A new stretched rev of the Falcon 9, super cryo introduced, return to flight and a 1st stage landing attempt, moved onto land instead of the barge, along with a multiple satellite launch. Wow and everything worked.

Steven Pietrobon · « **Reply #1550 on:** 12/22/2015 08:05 am »

From afar. Spotlight is on left.

First view of second stage after landing. Engine is out and stage is in orbit at 620 km and 7219 m/s.

Close view of first stage base. Can see small fire at the base of the stage to the right.

High fives all around at Hawthorn mission control (enhanced).

SpaceX workers behind mission control celebrating successful landing (enhanced).

Lars-J · « **Reply #1551 on:** 12/22/2015 08:11 am »

Quote from: Steven Pietrobon on 12/22/2015 08:05 am

Close view of first stage base. Can see small fire at the base of the stage to the right.

I don't think that is a fire... It seems too controlled. It almost looks like a vent burning off excess propellant/consumables as a part of the safing process.

Steven Pietrobon · « **Reply #1552 on:** 12/22/2015 08:15 am »

The satellites were in three rows. The top row had four satellites, the middle row three satellites and the bottom row four satellites. Each satellite weighed 172 kg and with the dummy weight in the middle row gives a payload mass of 172x12 = 2064 kg. Each satellite is about 1x1x1.5 m in size.

Deployment of first pair of satellites from top row. The other satellite can't be seen due to the viewing angle.

Deployment of second pair of satellites from top row.

Deployment of third pair of satellites from bottom row.

Deployment of fourth pair of satellites from bottom row.

Deployment of fifth pair of satellites from middle row.

Deployment of last satellite from middle row.

Successful mission! All satellites deployed.

Steven Pietrobon · « **Reply #1553 on:** 12/22/2015 08:18 am »

Another view of the second stage engine seen during the middle of satellite deployment.

Enhanced image of first stage. There seems to be smoke or vapour coming from the base.

Final view of first stage seen in broadcast (enhanced).

Kaputnik · « **Reply #1554 on:** 12/22/2015 08:30 am »

I wonder if HRissan of this forum can offer us his analysis of the landing, like he has done for the Grasshopper flights?

Aussie_Space_Nut · « **Reply #1555 on:** 12/22/2015 08:35 am »

Thanks for all the pics Steven! Much appreciated :-)

Steven Pietrobon · « **Reply #1556 on:** 12/22/2015 08:38 am »

From

http://www.spacex.com/news/2015/12/21/background-tonights-launch

"In the case of the Falcon 9 rocket, the boost stage is able to accelerate a payload mass of 125 metric tons to 8000 km/h and land on an ocean platform or to 5000 km/h and land back at the launch site."

"For a sea platform landing, the Falcon 9 figure of merit is therefore roughly 300 gigajoules (GJ) of kinetic energy and for a return to launch site landing, the number is about 120 GJ."

v1 = 8000 km/h = 2.22 km/s
v2 = 5000 km/h = 1.39 km/s
m = 125 t
Kinetic energy = ½mv²
E1 = 0.5*m*v1² = 0.5*125*2.22² = 308.0 GJ (close to Elon's value of 300 GJ)
E2 = 0.5*m*v2² = 0.5*125*1.39² = 120.8 GJ (close to Elon's value of 120 GJ)

"This solved the control problem and we were able to do two successful soft landings in the water. Max altitude of the rocket stage was 210 km, which doesn't matter a lot, and max transfer kinetic energy was 200 GJ"

For 125 t payload mass, 200 GJ translates to a speed of 1.79 km/s. From video, speed at separation was 1.65 km/s at 78.9 km altitude.

cartman · « **Reply #1557 on:** 12/22/2015 08:50 am »

So if the booster gave around 170GJ of energy to the payload (0.5*125*1.65²)then how did it manage to come back to the launch site? Is the 120GJ an understatement or was the payload significantly lighter than 125 tonnes?

ppb · « **Reply #1558 on:** 12/22/2015 08:52 am »

Can't remember what the ASDS attempts were like, but those legs sure deployed at the last possible moment. Reminded me of the landing gear deploy of STS-3 at White Sands.

francesco nicoli · « **Reply #1559 on:** 12/22/2015 08:56 am »

Quote from: cartman on 12/22/2015 08:50 am

So if the booster gave around 170GJ of energy to the payload (0.5*125*1.65²)then how did it manage to come back to the launch site? Is the 120GJ an understatement or was the payload significantly lighter than 125 tonnes?

of course the payload is significantly lighter than 125 tonnes. more likely, lighter of even 12.5!