Author Topic: SpaceX Merlin 1C Engine (Read 99875 times)

Comga · « **Reply #140 on:** 03/19/2008 07:46 pm »

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Big Al - 19/3/2008 12:22 PM
Found my source for the F9 delay, Orlando Sentinel.com, dated 2/28/08

Please post a link or quote.
That's a lot more of a delay than has been reported elsewhere.

Big Al · « **Reply #141 on:** 03/19/2008 09:16 pm »

Sorry, I can't come up with the link. I saw the orginal story over at Space Fellowship.com, but I can't even find that now. I also can't get the Orlando Sentinel archives to work for me. I'll keep at it.

Nate_Trost · « **Reply #142 on:** 03/19/2008 10:27 pm »

I suspect that refers to an 18-month slip from when SpaceX originally thought they'd fly the F9 (late 2007) when it was announced in 9/2005.

iamlucky13 · « **Reply #143 on:** 03/19/2008 10:56 pm »

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meiza - 19/3/2008 12:10 PM

Ha! So their chamber pressure is actually 800 psi = 55 bars. Haven't seen that officially mentioned in the spec sheets.

As it's from a 2+ year old update, I wouldn't take that as an official spec. That's pre-Merlin 1C and no precision given.

But I am innocently curious why the number excites you?

Big Al · « **Reply #144 on:** 03/19/2008 11:26 pm »

Bingo! http://blogs.orlandosentinel.com/news_space_thewritestuff/2008/02/bad-news-florid.html

Big Al · « **Reply #145 on:** 03/20/2008 12:17 am »

A second reading of the Orlando Sentinal article says a delay of the F9 flight from this summer until the 1st quarter of next year. Spacex was saying the first launch was to be the 4th quarter of this year, so I guess my 18 month delay was wrong. The Sentinal article was info from a Musk interview in Flight International.

meiza · « **Reply #146 on:** 03/20/2008 12:46 pm »

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iamlucky13 - 20/3/2008 12:56 AM

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meiza - 19/3/2008 12:10 PM

Ha! So their chamber pressure is actually 800 psi = 55 bars. Haven't seen that officially mentioned in the spec sheets.

As it's from a 2+ year old update, I wouldn't take that as an official spec. That's pre-Merlin 1C and no precision given.

But I am innocently curious why the number excites you?

Well afaik it's the last missing piece of spec, there has been some speculation about the performance of Merlin and the Falcons. Now it would be easier to figure for example what the ISP is for the big nozzle on Falcon 9's second stage.
I don't know *that* much about rocket engine design, but I hunch that usually chamber pressure is hard to increase much if you want to keep your expensive-to-develop turbines and pumps the same. The spin rate could be increased I guess.

Basically, chamber pressure determines ISP. With nozzle expansion rate and back pressure of course, but these tend to be pretty trivial: first stage nozzle is pretty close to small sea level optimized (exit pressure = back pressure = 1 bar), slightly bigger. And the vacuum big nozzle closes asymptotically in on infinite nozzle ideal ISP.

And flow rate with ISP determines thrust.

(This is just a simplified view of things...)

iamlucky13 · « **Reply #147 on:** 03/20/2008 03:47 pm »

Ah...I see.

Well, 800 psi is a hint then, but we can only assume one digit of precision meaning +/- 50 psi, further assuming that the number isn't significantly different for the Merlin 1C. So I'm guessing that only puts you within +/- about 20 seconds of the actual ISP.

josh_simonson · « **Reply #148 on:** 03/20/2008 05:26 pm »

I'd think the F9 second stage would be very similar to that of the first stage of the F1, which is already developed.

Crispy · « **Reply #149 on:** 03/20/2008 06:01 pm »

As far as I understand, the F9 2nd stage is designed to be very similar to the F9 1st stage, just with one engine and fewer tank sections. The aim is to maintain maximum comonality. The only common factor with Falcon 1 is probably the avionics.

rsnellenberger · « **Reply #150 on:** 03/20/2008 07:18 pm »

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Big Al - 19/3/2008 8:17 PM

A second reading of the Orlando Sentinal article says a delay of the F9 flight from this summer until the 1st quarter of next year. Spacex was saying the first launch was to be the 4th quarter of this year, so I guess my 18 month delay was wrong. The Sentinal article was info from a Musk interview in Flight International.

I haven't seen it mentioned here yet, but I just today noticed the following text at the bottom of SpaceX's manifest page:

*Target dates are for hardware arrival at the launch site.

Unless they've retconned the manifest by adding this recently, they only have to ship the F9 to the Cape by the end of the year to meet their target...

dmc6960 · « **Reply #151 on:** 03/20/2008 07:29 pm »

Its been the way for a few weeks now, since they've publicly stated that they will not launch F9 in 2008, but remain confident they can deliver the first F9 to Florida this year yet.

edkyle99 · « **Reply #152 on:** 03/20/2008 08:53 pm »

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dmc6960 - 20/3/2008 3:29 PM

Its been the way for a few weeks now, since they've publicly stated that they will not launch F9 in 2008, but remain confident they can deliver the first F9 to Florida this year yet.

The sliding scale manifest!

- Ed Kyle

meiza · « **Reply #153 on:** 03/21/2008 12:47 am »

Hehe, who believed their schedule originally anyway? Maybe they should be like the games business nowadays: Release date: "when it's done".

Chris-A · « **Reply #154 on:** 03/21/2008 12:51 am »

It would be nice to known what is the progress with the not-existent, or imaginary upper stage is going

rsnellenberger · « **Reply #155 on:** 03/21/2008 01:53 am »

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Chris-A - 20/3/2008 8:51 PM

It would be nice to known what is the progress with the not-existent, or imaginary upper stage is going

"It's like totally identical to the first stage, but we only use the center engine!" :cool:

Comga · « **Reply #156 on:** 03/21/2008 02:47 am »

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Crispy - 20/3/2008 1:01 PM
The only common factor (of the F9 second stage) with Falcon 1 is probably the avionics.

And using the turbopump exhaust for roll control
I have not seen confirmation that each F9 engine has two axis control.
It looks like the Saturn 1B used single axis steering on each of its eight engines. Can anyone confirm or refute this?

aero313 · « **Reply #157 on:** 03/21/2008 02:39 pm »

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Comga - 20/3/2008 11:47 PM

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Crispy - 20/3/2008 1:01 PM
The only common factor (of the F9 second stage) with Falcon 1 is probably the avionics.
And using the turbopump exhaust for roll control
I have not seen confirmation that each F9 engine has two axis control.
It looks like the Saturn 1B used single axis steering on each of its eight engines. Can anyone confirm or refute this?

You only need single axis steering. So long as the hinge axis is on a radial line from the center of the stage, four single-axis gimbals provide both attitude and roll control. This is how the Minuteman first stage works. The problem is that without two-axis gimbals on all the engines, I don't thing you have true engine-out capability for all failure modes.

daver · « **Reply #158 on:** 03/21/2008 03:06 pm »

Elon Musk and Richard Branson to save the world....or get rich trying.
http://www.iht.com/articles/2008/03/20/business/deal.php

AntiKev · « **Reply #159 on:** 03/21/2008 03:16 pm »

To be honest, Musk does not look happy to be there in that photo. I don't know if it was just the pose they put him in or his actual reaction.