Author Topic: Falcon I Flight 3 failure - A separate OPINION thread  (Read 78766 times)

Offline zaitcev

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Re: Falcon I Flight 3 failure - A separate OPINION thread
« Reply #220 on: 08/11/2008 12:13 am »
With the BDB notion comes the concept that you can realistically design a ground-launched (read: lifts off at sea level) LV using pressure-fed liquid engines.  Practically speaking, you can't.
This reminds me about the company with an unfortunate name "Rocket Propulsion", who tried to build a Falcon 1 class rocket with pressure fed engines all around. The name was unfortunate because it's impossible to do a web search for it. I don't remember who they were and how far the project went. They presented proposed cuaways, and even did some test fires of a small engine (or did they?). Another feature of their design was tankage of several diameters. I wonder if I imagined all that or they really existed, and if the later, what has happened.

Offline pippin

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Re: Falcon I Flight 3 failure - A separate OPINION thread
« Reply #221 on: 08/11/2008 12:19 am »
The name was unfortunate because it's impossible to do a web search for it.
You talk about this one?
http://www.rocketprop.com/
Learn Google, took me less than 2 min.!
« Last Edit: 08/11/2008 12:26 am by pippin »

Offline just-nick

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Re: Falcon I Flight 3 failure - A separate OPINION thread
« Reply #222 on: 08/11/2008 02:00 am »
I wrote up the rough Falcon 5/9 timeline in the following page.   
http://www.geocities.com/launchreport/falcon9.html
Thanks -- very interesting.  I hadn't realized quite how many design-redesign cycles they've been through.  It also makes me happy to see documented proof that they really did talk about a Merlin/RL-10 combo at least once.  I remembered reading about it in AvWeek a few years ago and nary a peep since then -- and was starting to question my sanity.  I guess Elon didn't want to get co-opted by the man from outsourcing engines!

  --Nick

Online Comga

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Re: Falcon I Flight 3 failure - A separate OPINION thread
« Reply #223 on: 08/11/2008 04:28 am »
The change came just after he was pictured with some gentleman from NASA signing an early cooperative agreement.
Gee, I signed a cooperative agreement with NASA earlier this year and never got my picture taken...  :D  :D  :D

The photo was in the February 2005 update.  The caption was "Signing the Space Act Agreement with Beak Howell, Director of NASA JSC".

If you want your photo published, perhaps you have to own the website. :D

But the stated connection may be wrong.  In the next update 6/50-9/05.  Musk said:

The History of Falcon 9

About eighteen months ago, a customer approached SpaceX with launch mass and fairing volume needs that exceeded the Falcon 5. We iterated on several different solutions, including upgrading the Merlin engine thrust and adding liquid or solid strap on boosters. All the options held significant drawbacks in cost, schedule or reliability, except one – a nine engine first stage.

At the time the two customers listed for the Falcon 9 were "US Government" and Bigelow.

From this one could draw inferences, but there is no hard evidence.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline just-nick

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Re: Falcon I Flight 3 failure - A separate OPINION thread
« Reply #224 on: 08/11/2008 04:57 am »
Alright, this is a little tangential, but since we're talking about the Falcon 5/9 history...

What is the staging/throttling profile for the Falcon 9 Heavy?  Both of the EELV "heavies" throttle the central stage so it gets >1 minute burn time after the peripheral boosters jettison.  Any similar plans for the 3-core Falcon 9 Heavy?  I'm not aware that Merlin can throttle, so do they just burn all three full bore?

Offline Patchouli

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Re: Falcon I Flight 3 failure - A separate OPINION thread
« Reply #225 on: 08/11/2008 06:17 am »
After seeing the full video I think they can fix the problem very easily and I'm glad it wasn't as bad a failure as I first thought it was.

I wonder if the first stage off a Falcon 1 could be used for other purposes then as the first stage of an orbital launch vehicle such as a reusable sounding rocket or lofting sub orbital vehicles?

As for switching to Falcon 9 from Falcon 5 I think it was a wise choice as it gives them a means to do EELV class payloads and lift a larger capsule with a lot more delta V and habital volume then their first concept.

The change got them from flying an equivalent to Gemini or stripped down Soyuz think Zond to flying a vehicle comparable to Orion or at least many of the old OSP concepts as far as LEO operations are concerned.

On using an RL10 based upper stage on Falcon 5 wouldn't that defeat the purpose of Falcon being a cheap vehicle with simple ground infrastructure needs since they would have to handle liquid hydrogen which would complicate ground operations?

It might be best to just demonstrate fast response low cost launches and reusability before adding the complexity of liquid hydrogen.

Offline Damon Hill

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Re: Falcon I Flight 3 failure - A separate OPINION thread
« Reply #226 on: 08/11/2008 07:06 am »
Alright, this is a little tangential, but since we're talking about the Falcon 5/9 history...

What is the staging/throttling profile for the Falcon 9 Heavy?  Both of the EELV "heavies" throttle the central stage so it gets >1 minute burn time after the peripheral boosters jettison.  Any similar plans for the 3-core Falcon 9 Heavy?  I'm not aware that Merlin can throttle, so do they just burn all three full bore?

The only "throttling" I can see with the Merlin engine is to turn it off; given nine engines there appear to be several possible "throttle settings", keeping vehicle controllability in mind.

The Merlin thrust upgrade to 125K lbs suggest a five-engine core might achieve about the same goal and save some money.

Offline kkattula

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Re: Falcon I Flight 3 failure - A separate OPINION thread
« Reply #227 on: 08/11/2008 07:59 am »
What are the critical points of the BDB concept?
...
With the BDB notion comes the concept that you can realistically design a ground-launched (read: lifts off at sea level) LV using pressure-fed liquid engines.  Practically speaking, you can't.
...

Armadillo have demonstrated VTVL with around 2000 m/s dv with pressure fed LOX/Ethanol.  This suggests a straight up and down pressure fed, low ER, first stage is practical (perhaps with higher energy fuel).

A second stage, (or second & third stages), designed to operate only in vaccuum, could be high MR with relatively low pressure tanks.

Admittedly this type of LV would be vulnerable to high G/P issues, but a modular design & rigorous sub-scale test program should be able to adapt. Unlike traditional "test-all-in-one" programs.

Offline JesseD

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Re: Falcon I Flight 3 failure - A separate OPINION thread
« Reply #228 on: 08/11/2008 07:52 pm »
One thing I have wondered about.  How much of a problem does fuel separation cause during staging? Does the simple cessation of first stage thrust (and subsequent acceleration reversal to -9.8m/s2) cause fuel slosh? or do surface tension and low levels of aerodynamic interaction let the stage and its fuel stay relatively together?  What are the effects of separation actuators? (springs, etc).  I imagine that the initial thrust would cause significant settling, but there's a gap between separation thrust and second stage ignition; what happens then? 

My suspicion is that the fuel would tend to stay stationary, when separation happens out of the atmosphere; but I may be forgetting something.

I'm sure there're knowledgable people on here, to whom this may seem a silly question; but still, anyone want to explicate?

Offline antonioe

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Re: Falcon I Flight 3 failure - A separate OPINION thread
« Reply #229 on: 08/17/2008 12:32 am »
In the next update 6/50-9/05.  Musk said:

The History of Falcon 9

About eighteen months ago, a customer approached SpaceX with launch mass and fairing volume needs that exceeded the Falcon 5. We iterated on several different solutions, including upgrading the Merlin engine thrust and adding liquid or solid strap on boosters. All the options held significant drawbacks in cost, schedule or reliability, except one – a nine engine first stage.

At the time the two customers listed for the Falcon 9 were "US Government" and Bigelow.

From this one could draw inferences, but there is no hard evidence.

(click!)

Thanks.
ARS LONGA, VITA BREVIS...

Offline mjfin

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Re: Falcon I Flight 3 failure - A separate OPINION thread
« Reply #230 on: 08/18/2008 08:39 am »
With the BDB notion comes the concept that you can realistically design a ground-launched (read: lifts off at sea level) LV using pressure-fed liquid engines.  Practically speaking, you can't.
This reminds me about the company with an unfortunate name "Rocket Propulsion", who tried to build a Falcon 1 class rocket with pressure fed engines all around. The name was unfortunate because it's impossible to do a web search for it. I don't remember who they were and how far the project went. They presented proposed cuaways, and even did some test fires of a small engine (or did they?). Another feature of their design was tankage of several diameters. I wonder if I imagined all that or they really existed, and if the later, what has happened.
Actually that would be me (rocketprop.com). We didn't actually try to build a Falcon 1 class vehicle, but we did extensive proof of concept studies with multiple model trajectory runs on a "notional" two stage pressure fed lox kerosene vehicle (with second by second isp adjustment of engine performance) at the request of the Air Force. It worked quite well. Works better with a small third stage. We found that lift off isp needed to exceed about 230 seconds to make it work. Our pressure-fed test engine -4500 lbf at Pc = 300 psia - routinely exceeded that significantly. The rest is attention to weight, and our structure was modern but not extraordinary: welded aluminum lox tank (heat treated in whole) and filiament wrapped kevlar fuel tank worked OK. Our engine (patented) is very light and very cheap. We have never had any shortage of hits on our (unfortunately named) web site . . .

Offline JWag

Re: Falcon I Flight 3 failure - A separate OPINION thread
« Reply #231 on: 08/18/2008 03:16 pm »
Welcome to the site, mjfin.  One of the best features of this site is the presence of actual people involved in spaceflight industry (as opposed to guys like me!)

Offline wannamoonbase

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Re: Falcon I Flight 3 failure - A separate OPINION thread
« Reply #232 on: 08/19/2008 02:01 pm »
Good question above about the Falcon 9 HLV core throttling.  Would it help in anyway to just install 7 or 8 engines instead of the standard 9? 

Save the engine weight and leave some fuel for burning longer after the staging event.
Wildly optimistic prediction, Superheavy recovery on IFT-4 or IFT-5

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