Author Topic: SpaceX: Elon Musk Interview, Part I  (Read 37845 times)

Offline Avron

  • Canadian Member
  • Senior Member
  • *****
  • Posts: 4930
  • Liked: 156
  • Likes Given: 160
Re: SpaceX: Elon Musk Interview, Part I
« Reply #20 on: 08/17/2006 06:00 pm »
Would you fly on version 1.0 or 2.0 ... I like the 1. or 2. something versions

Offline BarryKirk

  • Member
  • Full Member
  • **
  • Posts: 280
  • York, PA
  • Liked: 7
  • Likes Given: 16
Re: SpaceX: Elon Musk Interview, Part I
« Reply #21 on: 08/17/2006 06:54 pm »
Well.... You've got a point there...

But, The first few launches of a X.00 rev should be unmanned.

The minor rev numbers could be used for critical improvements required before the next major rev level.

Offline josh_simonson

  • Veteran
  • Full Member
  • ****
  • Posts: 504
  • Liked: 2
  • Likes Given: 0
Re: SpaceX: Elon Musk Interview, Part I
« Reply #22 on: 08/18/2006 01:19 am »
Minor issues come up all the time that need addressing, I'd rather have folks monitoring that and responding to it than plugging their ears and singing "lalalalala..."

Offline selden

  • Member
  • Member
  • Posts: 45
  • Liked: 2
  • Likes Given: 0
Re: SpaceX: Elon Musk Interview, Part I
« Reply #23 on: 08/18/2006 12:19 pm »
Except, of course, that at some point you have to say "enough". and launch.
It's a truism that "perfection is the enemy of good enough."

That's one of the problems that senior management had to cope with for the Saturns.
Engineering changes were required to be approved at the very highest level in order to keep the continuous, minor, unnecessary changes from disrupting the entire schedule.
Selden

Offline antonioe

  • PONTIFEX MAXIMVS
  • Full Member
  • ****
  • Posts: 1077
  • Virginia is for (space) lovers
  • Liked: 43
  • Likes Given: 0
Re: SpaceX: Elon Musk Interview, Part I
« Reply #24 on: 08/18/2006 04:46 pm »
As the designer of Pegasus, I'm appalled by Elan Musk's incorrect statements.  His characterization of Pegasus as a "five stage rocket" is at best uninformed, at worse misleading.  The airplane is just that: an airplane, not a rocket stage.  A Lockheed 1011 works as well as a B-52.  I'd rather characterize it as a mobile launch platform that has allowed me to launch Pegasus from WTR, ETR, Wallops, the Canary Islands (where there was NO range at all) and Kwaj.  We have not spent a dime on infrastructure where he has stated in public that he spent $20M on facilities between Kwaj and Vandenberg.  And no, we don't have "dedicated pilots", we hire Bill Weaver, the legendary SR-71 test pilot, and his friends on a per-flight basis (they are free-lancers that work for other customers in between).

The optional HAPS is not an "apogee stage".  If it were, the majority of Pegasus flights (which don't use HAPS) would never make it to orbit.  It is used in a few flights to change the orbit, for example between deployment of two satellites that want different orbital altitude and inclination.  Can his "simpler" rocket do that?

As for other complexity, given that his avionics are probably similar to mine, I am willing to bet that one of his liquid stages - nay, one of his liquid motors! - has more moving parts, valves, actuators, pressurant tanks, plumbing, sensors, actuators and aluminum nuts that the entire Pegasus!

As for Pegasus requiring a "man-rated range", well, I was the launch panel operator on the B-52 during the first launch.  I wrote the launch countdown procedures (Don Thoma did the range interface).  Compared with a typical Vandenberg launch, it was a lot simpler, because the rocket never flies closer than 50 miles from terra firma; the only "man-rating" elements were of the "wear hard hats and steel-toed boots while handling big loads" kind!

Finally, the first rocket stage is not "a complete hypersonic airplane" as he states.  I designed it over a period of a few weeks, and I agree, as he's quick to point out, that I'm not "the smartest person on earth".  Burt Rutan builds the wing (based on a hand sketch for the planform that I gave him) and that's the end of it.

What I can't figure out is whether he's deliberately misinforming people or simply doesn't know squat about rockets (actually, I think he does...)  Perhaps his strategy is this: a) Make people believe he can sell rockets for $6M a pop b) drive Orbital out of the business and c) start charging all the market can bear, most likely a lot more than $20M - it's the only way to recover the over $100M he's put into it.  We only spent $50M on the supposedly more complex five-stage, man-rated Pegasus...
ARS LONGA, VITA BREVIS...

Offline braddock

  • NSF Private Space Flight Editor
  • Full Member
  • ****
  • Posts: 991
  • Liked: 16
  • Likes Given: 8
Re: SpaceX: Elon Musk Interview, Part I
« Reply #25 on: 08/18/2006 05:19 pm »
A privilege to have you with us, Dr. Elias!

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 37440
  • Cape Canaveral Spaceport
  • Liked: 21450
  • Likes Given: 428
Re: SpaceX: Elon Musk Interview, Part I
« Reply #26 on: 08/18/2006 05:28 pm »
Dr. Elias,

I was at your first concept briefings to Space Division at LAAFB.  Your briefing explained that you scaled up the F-15 launched ASAT.  As a lowly captain, I was intrigued by the concept and was hoping my organization would be involved.  Unfortunately, they weren't and but I had other interesting work.  Our paths sort of crossed again when I was at EAFB for a shuttle landing and the first or mockup Pegasus was rolled out.   Now I work for the Pegasus's main customer.  

I agree with you completely wrt Spacex.  Anybody can build a rocket, the hard part is to keep flying them successfully  and make a profit

You have another friend (aero313) on this site who is a former OSC empl0yee

Offline antonioe

  • PONTIFEX MAXIMVS
  • Full Member
  • ****
  • Posts: 1077
  • Virginia is for (space) lovers
  • Liked: 43
  • Likes Given: 0
Re: SpaceX: Elon Musk Interview, Part I
« Reply #27 on: 08/18/2006 10:47 pm »
So... you found me up, in spite of my cleverly disguised screenname!...  Next guy that calls me "Dr." gets to take two aspirins and call me in the morning, I'm late for my round of golf.

*SIGH*... people forget that, unlike microelectronics, where we still have a few rounds of "Moore's law" to go before quantum physics hits us in the head, we reached the PHYSICAL LIMITS of the two fundamental parameters of rocketry: specific impulse and mass fraction, in the mid-60's and the late 50's, respectively!!!  The specific impulse of LOX-LH2 engines, around 450s, represents the limits impsoed by INTRAmolecular bonds in this here known universe; the BEST mass fraction ever acheived on a launch vehicle stage was the Atlas, and unless somebody comes up with rocket-sized nanotube structures, mass fractions have reached the limits of INTRAmolecular bonds in the abovementioned universe.

So there is NO WAY OF REDUCING THE COST OF LAUNCH BY TECHNOLGY.  What else can we do?  Oh, yes, automate the manufaturing of the rocket.  I bet you I can build 100,000 Pegasi (Pegasuses?) for about $1M each... can you sell them?  Well, we could reuse them... problem is, NASA calculated in 1970 that a reusable (multistage, not SSTO!) launch vehicle becomes cheaper than an expendable around 50-60 flights a year... no problem!  Shuttle will fly *100* times a year!!! (cough, cough...)  Around 2000, NASA paid six companies (Orbital amongst them) several millions of $$$ to research "Seconf Generations RLV's" and they found out that RLV's become cheaper than ELV's at the rate of... are you ready?... 50-60 flights/year!  Why?  Isp amd mass fraction are the same today as they were in 1970.

Hmm.. what else can we do?  Oh, yes!  Have somebody else pay for the development, and don't pay them back!  That helps... What else?  Oh, yeah, if you can't reduce the number of hours it takes to build a rocket, how about reducing how much you pay per hour? (look behind you PC and tell me wher it's built... El Segundo?  Try again.)

If you KNEW you were going to sell 15-20 flights a year, you could go hybrid (no, I don't mean solid/liquid, I mean one stage reusable, one expendable) cheaper than expendables... perhaps if you combine the free, or semi-free development and the partially reusable... oh my aching back!  I must be really getting old, as somebody on a different forum put it (we're "old space", you know... no, wait!  Better yet!  Lockheed-Martin and Orbital are "two behemoths of the aeropace industry!"... we are the world's smallest giant!!!!)
ARS LONGA, VITA BREVIS...

Offline BarryKirk

  • Member
  • Full Member
  • **
  • Posts: 280
  • York, PA
  • Liked: 7
  • Likes Given: 16
Re: SpaceX: Elon Musk Interview, Part I
« Reply #28 on: 08/18/2006 11:50 pm »
Well, Thank you for your input.

Got a question....

By using a "jet" as a first stage you are reducing the delta V required for the "rocket" portion of the launcher.  Also, the "rocket" portion of the launcher operates at a higher ISP because most of your boost occurs with thin to no atmosphere.

How much of a savings in delta V do you get by airlaunch?

Online Chris Bergin

Re: SpaceX: Elon Musk Interview, Part I
« Reply #29 on: 08/19/2006 12:41 am »
Quote
antonioe - 18/8/2006  11:34 PM

So... you found me up, in spite of my cleverly disguised screenname!...  Next guy that calls me "Dr." gets to take two aspirins and call me in the morning, I'm late for my round of golf.


Heh. Trick is to call yourself "Bob" as all the NASA types on here have started to do.

Welcome to the site, and rest assured, your comments will likely be read by the very person that came up with the opposing view. For the purpose of objectivity, we'll be happy to air such counter-claims, should there be a wish.
Support NSF via L2 -- Help improve NSF -- Site Rules/Feedback/Updates
**Not a L2 member? Whitelist this forum in your adblocker to support the site and ensure full functionality.**

Offline antonioe

  • PONTIFEX MAXIMVS
  • Full Member
  • ****
  • Posts: 1077
  • Virginia is for (space) lovers
  • Liked: 43
  • Likes Given: 0
Re: SpaceX: Elon Musk Interview, Part I
« Reply #30 on: 08/19/2006 04:32 am »
No, I should have used "Dave" - at Orbital, the preferred name is "Dave": my boss is Dave Thompson, Dave Steffy and David Low work with me, Dave Anhalt and Dave Aderhold work for Dave Steffy, Dave Hastman runs manufacturing, and so on...

On BarryKirk's question: Well, the aircraft's groundspeed for most launches is 770 feet per second... winds change a bit (usually help for low inclination launches, not so much for high inclination...) but that translates to a 1 for 1 savings in DV.     Other savings come from  1) The lower air pressure, which helps in two ways: first, less exhaust losses to begin with, but also, a higher optimal expansion ratio than if you began life at S/L, both good probably for 1,000 fps 2) gravity losses, which are proportional to sin(flight path angle), and Pegasus never gets much above 30 degrees... this one's a big one... probably 1,000 fps savings or so... 3) Turning losses, again, the flight path is quite flat - this one is not a big deal, maybe 100-200 fps (warning: the losses are NOT additive!!!)

On the minus side, you have to add about 1,000 lbs of wing, and the lift-induced and wave drag of the wing (note, however, that the wing is absolutely necessary to be able to take advantage of the aircraft's groudspeed and the altitude - those that throw the rocket off the aft end of an aircraft and fire it vertically loose a lot, probably half, of the DV advantages of air launch)

I once ran two POST runs, one with a regular Pegasus traj, then another with a vertical, ground launched "Pegasus" sans wing and fins, but with the same stage 1 expansion ratio as the first one... can't remember what the ideal DV difference was... I seem to remember about 2,000-2,500 feet per second, but I *DO* remember a change of payload from about 200 Kg to over 340 Kg (that was the original Pegasus, not the XL, and I can't remember the orbit, it probably was sun-synch).  2,500 feet per second of DV may not seem a lot compared with the 30,000 fps of IDEAL (or "delivered") DV that you need to get there; but due to the non-linearity of the rocket equation, it means a lot, perhaps as much as a 40% increase in "throw mass" (total mass in orbit).  For a small rocket like Pegasus, where the avionics and other "fixed" systems mass tax on the last stage (the THIRD one, Elon, the THIRD one...) is relatively high (say, 50%), the 40% increase in final throw mass can increase your payload 80%!!!  For larger rocket with a low throw mass overhead, it decreases back towards the raw throw mass increase.  Of course, air launch "maxes out" around Pegasus size unless you build a heck of a special aircraft...
ARS LONGA, VITA BREVIS...

Offline antonioe

  • PONTIFEX MAXIMVS
  • Full Member
  • ****
  • Posts: 1077
  • Virginia is for (space) lovers
  • Liked: 43
  • Likes Given: 0
Re: SpaceX: Elon Musk Interview, Part I
« Reply #31 on: 08/19/2006 12:29 pm »
Oops.. I made a mistake in my post #58259... when I pontificated that specific impulse and mass fraction have reached the 97% asymptote of the laws of physics... specific impulse of chemical rockets is limited by the energy contained in INTRAmolecular bonds (e.g., between the H and O atoms of water), while structural mass fraction is limited by INTERmolecular bonds (between molecules of, say, carbon graphite).  I type INTRA on both...
ARS LONGA, VITA BREVIS...

Offline braddock

  • NSF Private Space Flight Editor
  • Full Member
  • ****
  • Posts: 991
  • Liked: 16
  • Likes Given: 8
Re: SpaceX: Elon Musk Interview, Part I
« Reply #32 on: 08/19/2006 01:22 pm »

Offline edkyle99

  • Expert
  • Senior Member
  • *****
  • Posts: 15391
    • Space Launch Report
  • Liked: 8565
  • Likes Given: 1356
RE: SpaceX: Elon Musk Interview, Part I
« Reply #33 on: 08/19/2006 03:30 pm »
Quote
Cretan126 - 30/7/2006  8:24 PM

SpaceX has been very coy about mentioning the mighty fireball that occurred when the vehicle hit the reef.


Interesting, isn't it, that we have, available on the Internet, images of the might CRATER dug by the crashed Russo-Ukrainian Dnepr last month, along with closeups of bits and pieces of rocket (an operational Russian ICBM, mind you) and satellites, but we still have not seen photo-one of the Falcon crash site.  

 - Ed Kyle

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 37440
  • Cape Canaveral Spaceport
  • Liked: 21450
  • Likes Given: 428
Re: SpaceX: Elon Musk Interview, Part I
« Reply #34 on: 08/19/2006 06:03 pm »
Not anybody can to get to Kwaj.  Not a tourist destination.

Offline astrobrian

  • NSF Photographer
  • Senior Member
  • *****
  • Posts: 2922
  • Austin Texas
  • Liked: 23
  • Likes Given: 112
Re: SpaceX: Elon Musk Interview, Part I
« Reply #35 on: 08/19/2006 07:20 pm »
Maybe not a tourist destination, but one would think that since the investigation of the crash is over that a few pictures could be obtained from SpaceX

Offline yinzer

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1509
  • Liked: 3
  • Likes Given: 0
Re: SpaceX: Elon Musk Interview, Part I
« Reply #36 on: 08/19/2006 07:41 pm »
Didn't it crash into the lagoon?  Hard to make a crater in those...

Not to mention that the Dnepr crash caused a middling international incident and also called into question the effectiveness of a large part of the Russian ICBM force, both of which are more newsworthy than the SpaceX crash.
California 2008 - taking rights from people and giving rights to chickens.

Offline aero313

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 516
  • Liked: 6
  • Likes Given: 0
Re: SpaceX: Elon Musk Interview, Part I
« Reply #37 on: 08/19/2006 11:46 pm »
Quote
yinzer - 19/8/2006  3:28 PM

Didn't it crash into the lagoon?  Hard to make a crater in those...

No, you do make a crater.  It just fills in really fast....  (BADDA BING)

Quote
Not to mention that the Dnepr crash caused a middling international incident and also called into question the effectiveness of a large part of the Russian ICBM force, both of which are more newsworthy than the SpaceX crash.


Keep in mind that Dnepr is also hypergolic and about the size of a Titan II, so the bang was probably a little bigger.

Offline RandomVector

  • Member
  • Posts: 2
  • Liked: 0
  • Likes Given: 0
Re: SpaceX: Elon Musk Interview, Part I
« Reply #38 on: 08/20/2006 07:44 am »
Astronautix (http://www.astronautix.com/lvs/pegasus.htm) says Pegasus is a 5 stage rocket....

Model: Pegasus/HAPS. Family: Air-Launched. Country: USA.
5 stage version consisting of 1 x NB-52 + 1 x Orion 50S + 1 x Orion 50 + 1 x Orion 38 + 1 x HAPS
LEO Payload: 250 kg (550 lb). Apogee: 4,000 km (2,400 mi). Liftoff Thrust: 580.000 kN (130,380 lbf). Total Mass: 18,500 kg (40,700 lb). Core Diameter: 1.28 m (4.19 ft). Total Length: 15.50 m (50.80 ft).

Offline RandomVector

  • Member
  • Posts: 2
  • Liked: 0
  • Likes Given: 0
Re: SpaceX: Elon Musk Interview, Part I
« Reply #39 on: 08/20/2006 07:46 am »
... (with HAPS)

Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
0