SpaceX Successfully Tests Nine-Engine Cluster

the_other_chewey writes "At their test facility in Texas, SpaceX, the privately funded space-flight company, have successfully tested their nine-engine cluster which is planned to provide the heavy lifting capability for their Falcon 9 and Falcon 9 Heavy rockets. The firing lasted three minutes (a full 'mission duty cycle,' i.e. a simulated launch) under full power, delivering 3.8MN (or 855,000 lbs.) of thrust. SpaceX have made a video of the test available. The Waco Tribune has a short report about it, with comments by locals."

Re:FP

[v1]

Awesome, simply awesome. Glad to see they passed the test, or at least didn't blow up. Hope they got some good test data. Ideally they were giving it some control feedback to make sure the gimbals etc that aim the rocket were all responding correctly, performing their orbital roll etc. Getting the most bang for the buck (without the bang!) since I'm sure this test cost a not-so-small fortune considering the fuel used.

As for the "why didn't it take off" question, it was pretty firmly fitted to the ground. Despite it's size and total impulse capacity, that's over a 3 minute span. It's not designed to lift more than itself and its payload, at a marginal acceleration. The thrust output is variable also, and can't be allowed to crush the payload with G-forces. Despite its massive size, it wasn't going to be going anywhere.

I'd be interested to know the power curve on the rocket. Most of the fuel is actually spent lifting the FUEL. From one viewpoint, the engine could be constant-thrust, and would accelerate slowly at first, and increase its acceleration as it consumed fuel and became lighter with the same thrust. Or it could back off the thrust as it got lighter, to prevent the g-forces from acceleration from becoming too great for the vehicle or its payload. I'm sure the power-to-weight-ratio could get really high as it nears the end of its firing if it were left at maximum thrust. Anyone happen to know the power curve or acceleration curve on ascent? I thought I read somewhere they try to keep the g-forces under 8g, and not for too long of a period of time, at least for crew.

Re:FP

[hcdejong]

Does anyone know how tall that test stand is.

The Falcon 9 first stage on top of the stand is about 25 m high (I've assumed it's half the total height of the Falcon 9). The stand appears a bit over 2x as high as that first stage, so 60 m/180 ft would be my initial guess.

Re:Fear in the comments sad

[Anonymous Coward]

Actually, there is someone there saying 'this is what happens when you elect Obama.'

Re:Congrats SpaceX

[ComputerInsultant]

Unless NASA releases money for COTS-D very soon, we will still have a manned launch gap. The Falcon 9 and Dragon are man rated, but to launch people into using the Falcon 9 and Dragon, you need much more. You need a Launch Escape System and a Emergency Egress System. Neither of these is currently in development at SpaceX and both have a long lead time to develop.

Without the additional COTS-D money to start development on these systems, SpaceX will not carry people until they find the money from other sources to fund these development efforts.

Re:FP

[CrimsonAvenger]

The Falcon 9 first stage on top of the stand is about 25 m high (I've assumed it's half the total height of the Falcon 9).

The Falcon 9 is 54.9 meters tall. The first stage is a bit more than half that height, so call it 30 meters.

Re:Congrats SpaceX

[Nyeerrmm]

This test was the last major step before shipping it to the cape, so it seems the schedule on the website with delivery scheduled by Q408 is accurate. As far as when it launches... my WAG is by summer. From what I can tell getting it to the cape is largely a move to show the new administration "hey, remember us and COTS", so there may be a bit more work that has to be done on it.

Here's hoping the lessons from F1 carry over and there aren't new issues to discover.

Re:FP

[Nyeerrmm]

The website says the top of the BFTS ("Big Falcon Test Stand") is 235 feet high. Presumably this includes the blue "Stairway to Heaven" running up the side of the first stage, so I'd say the concrete stand is probably about 150 feet... having been up to the top I must say it's impressive, and a little scary. Fortunately theres an elevator up to the concrete platform, but only too steep stairs up to the top from there.

Also, while I love the company, I woudl say that they did just buy the site, including the test stand from another company that I can't remember the name of off the top of my head.

Re:FP

[bazookazuz]

I work for the TX facility. The concrete tripod is 120' tall and the legs are 10' in diameter. The stage is 85' tall and 12' in diameter. You can see it 25 miles away when you are driving to work. It is pretty awesome (-;

Re:FP

[rabidkumquat]

850,000lbf (lbf = pounds force) is a relatively small load. It is easy to forget exactly how strong steel is in tension: using standard 50ksi steel (typical structural steel), only about 18 sq-in would be required to hold the rocket down (albeit with no factor of safety).

For comparison, the main cables in the George Washington suspension bridge in New York each carry ~260,000,000lbf [jhu.edu], and are designed to resist almost 3 times that load. While the amount of thrust developed by the Falcon 9 is seriously impressive for a lift vehicle, it is trivial from a ground-based engineering standpoint.

There is a reason structural engineers work in kips not pounds (1 kip = 1000lb), and yes IAASE.

Re:FP

[evanbd]

There are nine engines in a cluster. Burn time for the cluster is 178 seconds. All engines run at full throttle. At t+160s, they shut down a pair of engines to reduce the g loading slightly, but otherwise it's constant thrust. Remember, though, that liftoff acceleration is very mild -- about 1.2g, iirc. For a given engine thrust, you usually improve payload mass by adding tankage until it can just barely leave the pad.

Re:Rail Gun...

[holmstar]

You would need one HECK of a heat shield to withstand flying at escape velocity so deep in the atmosphere. I'm sure it could be done, but it would look like a meteor flying up instead of down.

Video from farther away

[the_other_chewey]

I came across an additional amateur video from farther away after submitting the story:
http://uk.youtube.com/watch?v=i9n6rYoSGNQ [youtube.com]

SpaceX' video unfortunately lacks the proper amount of bass
to really give a sense of the sheer power shown.

Comment removed

[account_deleted]

Comment removed based on user account deletion

Re:How long before the tree huggers complain

[osu-neko]

You realize most of the Hiroshima survivors weren't even inside refrigerators, right? Just curious why that scene seems so unbelievable to so many people. There are people around today who were close enough to the blast that it destroyed the building they were in. They had to be dug out of the rubble of the building that collapsed around them. But they're still alive and kicking in 2008. Unless you're literally at ground zero, surviving a nuclear blast, particular the old A-bombs, really was pretty much as simple as ducking and finding cover. There are over 50,000 alive today who didn't even do that in Hiroshima and are still around...

Re:How long before the tree huggers complain

[nasor]

Nuclear weapons are not nearly as "unsurvivable" as many people apparently believe. You might be interested to know that about 7% of the people at Hiroshima who were within 1000 feet of the blast site survived. I'm sure Indy has beaten worse odds before :)