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« on: 08/19/2006 01:19 PM » |
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braddock
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« Reply #1 on: 08/19/2006 01:49 PM » |
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Antonio,
In the other thread you mentioned "there is NO WAY OF REDUCING THE COST OF LAUNCH BY TECHNOLGY", and that automated manufacturing or reusability doesn't give cost gains until the market volume goes up, and that the only other option was to pay people less.
Clearly Orbital is at or near the lower cost bound for a small payload US launcher.
Do you also think the larger EELV-class launch vehicles are already at the lower bound of profitable price as well? Or is there more room for innovation in process, overhead, and construction for the larger payload market?
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Spiff
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« Reply #2 on: 08/19/2006 01:56 PM » |
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Antonio, I noticed this remark you made in the other thread: 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
This approach is the way that t-space intends to go in their air launches. Any idea why they chose this approach if it loses them half their air launch advantage? Thanks in advance! Spiff P.S. I know this question is not specific to Pegasus, I'm just wondering because it seems like a strange approach.
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SimonShuttle
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« Reply #3 on: 08/19/2006 02:05 PM » |
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Antonio.
What do you think of the ESAS/VSE vehicles, especially the "5 seg Stick" which is going through major problems in the design cycles. Many engineers think the CLV is a bad design, but what do you think and do you have a prefered configuration?
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Chris Bergin
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« Reply #4 on: 08/19/2006 07:12 PM » |
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Allow me to place this higher up the forum (I can move it back into this section when completed). I want to give it more exposure.
I would urge people to aim to keep their questions on the Pegasus, as opposed to going too far off topic.
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Jim
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« Reply #5 on: 08/19/2006 07:19 PM » |
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Great idea. Also concur wrt limiting questions but do have a suggestion that the topic includes all of OSC's LV's and or products.
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Zond
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« Reply #6 on: 08/19/2006 07:43 PM » |
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Antonio, if i understand it correctly, you will be in charge of the Kistler K-1 program, so congratulations on getting a COTS space act agreement. This also leads me to my first question. In the other thread you said: 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.
You seem sceptical of RLV's, so why did you accept to manage what may become the first orbital RLV: the Kistler K-1? Orbital has a lot of success in producing small GEO comsats. The K-1 could be used as a launch platform for these sats, was this one of the reasons Orbital decided to invest in Kistler? I once read a comment that said that the payload that is gained by the lift provided by the wings of the Pegasus is cancelled out by the weight of the wings. So a wingless Pegasus would put up the same payload as winged Pegasus. Do you believe this to be true? If yes, why did you put (and keep) the wings on the Pegasus? The major customers for the Pegasus are the DOD and NASA. The only commercial launches of the Pegasus were bought by Orbital. Do you think there will be other commercial payloads on the Pegasus in the future? And do you think there is (or will be) commercial demand for launchers in the Pegasus payload class? Thanks in advance! (And i hope you will return in the future to answer questions concering the K-1)
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antonioe
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« Reply #7 on: 08/19/2006 08:18 PM » |
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Whoa... whoa... one at a time...! (... what did I get myself into... Bergin, I'll get you for this!...)
Seriously: I'll try my best to answer each and every question, please be patient with me. I'll also try to be as objective as I can, but please forgive me in advance, 'cause, like Zaphod Beeblebrox's great-grandfather, I tend to pontificate a lot.
"What can be done to EELV's" - Not much, I'm afraid. Let me start by stating that both Atlas V and the Delta IV families are fine rockets. Their track record is impressive: as of April/May 2006, the Atlast V is 8 for 8 and the Delta IV is 6 for 6, although one launch was a little rocky. When Doug Stanley was directing Orbital's Space Transportation Architecture Studies (STAS) and started advocating the use of EELV's for human LEO transportation, we looked closely at the two rockets. [Historical note: we thought it would be "cute" to put up some posters of Doug's work - including a picture of the BLB3 vehicle on top of a Delta IV heavy - on display inside the L-1011 on occasion of the X-34 rollout at Dryden, which Dan Goldin attended. When Dan saw the picture, he hit the ceiling and chewed poor Doug really bad, proclaiming that "this country will NEVER again send an astronaut on an expendable vehicle..."] From a purely engineering standpoint I like the Atlas V a little more.
The problem of EELV cost has, IMHO, two major elements:
1.- The existing EELV infrastructure has the capacity to produce, test and launch probably 12 to 18 vehicles a year. Given that there are two different manufacturers and two different launch ranges, I don't hink you could come up with anything less. But the 14 launches from August 2002 to May 2006 average about 3.5 launches/year! The government has come to grips with the reality that this town ain't big enough for two EELV;s and, since they cannot in all fairness select one company vs. the other, they have told them to merge, like NASA did on Shuttle operations. United Launch Alliance will ameliorate, but not totally eliminate this problem.
2.- The so-called “bureaucratic overhead” (some of which is honest procedural thoroughness and rigor) is inevitable: launch is but a fraction of the cost of a commercial or military space project; if you have a $75M satellite riding on a $16M Pegasus (as NASA does very frequently), and Orbital comes to you and sez “I can save you $2M if you don’t ask me to prepare all those pedigree and launch readiness reviews you ask me for – and don’t worry, they don’t really add anything to the launch reliability” – what would you do? What is the impact of saving $2M on a program that spends $75+$16M+probably $20M more for science and flight operations? What if YOUR launch were to fail? You would say “thanks, but no, thanks”.
That’s what’s maddening: given the boundary conditions they have to operate within, THEY ARE MAKING RATIONAL DECISIONS! SO, you must either ask them to behave irrationally, or change the boundary conditions.
I’ll be back after making myself a cappuccino.
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antonioe
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« Reply #8 on: 08/19/2006 08:34 PM » |
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“Any idea why t/Space intends to drop their rocket from an aircraft so it lights vertically even if it reduces the DV advantage of air-launch?”
Well, to begin with, it would be presumptuous of me to speculate on why t/Space, or anybody else, chooses a specific design or another. I can speculate on why *I* would choose that approach, instead of the one I chose on Pegasus.
Near-vertical launch loses the forward velocity and gravity losses of wing-assisted horizontal drop, but retains almost all of the pressure advantages of the altitude start. In particular, it would allow me to use a pressure-fed first stage, whereas a pressure-fed first stage at sea level would be the kiss of death.
Also, I could use relatively unmodified military cargo aircraft using a rear-ramp extraction method; if I had to launch 6 air-dropped rockets within 10 minutes, 6 C-17's would do the trick.
There is also the issue of the Orbital Pegasus patent, which covers the wing, although I’m sure Orbital would be glad to license it at a very reasonable rate to anyone foolish enough to think there’s a market there for another Pegasus-class vehicle… we barely make a living out of it…
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antonioe
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« Reply #9 on: 08/19/2006 08:40 PM » |
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"What do you think of the ESAS/VSE vehicles".
I haven't paid much attention to them, except through the work we did on the Launch Abort System (LAS) for the Crew Exploration vehicle (CEV) so I can't comment. Only a thought on the use of solids for a crew-carrying vehicle: hard to get out of their way with their large thrust levels and difficulty of thrust termination.
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antonioe
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« Reply #10 on: 08/19/2006 09:11 PM » |
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“You seem sceptical of RLV's, so why did you accept to manage what may become the first orbital RLV: the Kistler K-1?”
First, Orbital is NOT going to manage the K-1 effort: we will supply RpK with systems engineering and several other high-skill resources (which, admittedly will include management, such as G. David). But RpK will be clearly in control.
I’m not “skeptical”: I only point out that you need a lot of traffic (50-60/year) for RLV’s to compete with ELV’s. Unless, of course, you only have to pay back half of the investment, which is the situation with Kistler.
Finally, of ALL the RLV configurations I’ve seen, George Mueller’s K-1 seems to me the most likely to succeed, specifically because of its configuration is such that the necessary high mass fractions may be achievable, especially on the critical upper stage (“Orbital Vehicle”).
It remains to be seen if the NASA COTS funding survives future budget battles, Shuttle/ISS/Constellation overruns, gulf coast hurricanes and changes in administration…
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yinzer
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« Reply #11 on: 08/19/2006 09:35 PM » |
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I would like to say that I'm impressed with what Orbital has accomplished. They were the first people to make commercial space work.
Three questions:
Surely the Pegasus wing patent has expired by now?
As someone with experience in the business side of launch operations, can you comment on just how much flight rate affects ELV pricing? Would we come out ahead if we doubled/tripled the EELV flight rate by moving all Delta II size payloads onto it and ditching Delta II entirely?
Do you feel that the laws preventing the use of surplus ICBM hardware for space launch are wise in retrospect? With 50 Peacekeepers left over, it seems like the payload side of the low-cost space problem could get a big boost from those being made available.
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aero313
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« Reply #12 on: 08/19/2006 11:39 PM » |
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antonioe - 19/8/2006 4:21 PM
“Any idea why t/Space intends to drop their rocket from an aircraft so it lights vertically even if it reduces the DV advantage of air-launch?”
Near-vertical launch loses the forward velocity and gravity losses of wing-assisted horizontal drop, but retains almost all of the pressure advantages of the altitude start. In particular, it would allow me to use a pressure-fed first stage, whereas a pressure-fed first stage at sea level would be the kiss of death. Actually, not much of the forward velocity is lost. Keep in mind that the AirLaunch LLC (not t/Space) system does not use the parachutes and pallet the way SRALT/LRALT do. Ignition takes place when the rocket has pitched up to nearly vertical, but there is still significant forward velocity. Of course, the low thrust to weight of a liquid results in the vehicle continuing to fall for several seconds and the 90 deg AOA is not a normal launch vehicle design case. Also, I could use relatively unmodified military cargo aircraft using a rear-ramp extraction method; if I had to launch 6 air-dropped rockets within 10 minutes, 6 C-17's would do the trick. Actually, the DARPA surge requirement was 16 in 24 hours, or something like that. Additionally, AirLaunch only pays for the marginal cost of flight hours - for some reason they don't want to own a dedicated aircraft... Also, since DARPA/Falcon is a DoD system, stealth is a consideration. To an observer it looks just like any other C-17 taking off. There is also the issue of the Orbital Pegasus patent, which covers the wing, although I’m sure Orbital would be glad to license it at a very reasonable rate to anyone foolish enough to think there’s a market there for another Pegasus-class vehicle… we barely make a living out of it… Actually, the wing wouldn't fit very well inside the C-17. Also, with the low thrust/weight of a liquid, the carrier aircraft gets further away faster with the near vertical initial ascent than with a belly-mount horizontal drop. By the way, congrats on COTS.
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antonioe
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« Reply #13 on: 08/20/2006 01:41 AM » |
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“I once read a comment that said that the payload that is gained by the lift provided by the wings of the Pegasus is cancelled out by the weight of the wings. So a wingless Pegasus would put up the same payload as winged Pegasus. Do you believe this to be true? If yes, why did you put (and keep) the wings on the Pegasus?”
Answer , Page I (having trouble fitting the entire answer into one submission):
Rather than argue about it, why don’t we calculate it? Open an Excel window and paste the following spreadsheet table to it:
S1 S2/BF S2/AF S3
Payload, Kg 5,729 3,657 1,299 341
Inert, Kg 2,241 169 455 180
Final, Kg 7,970 3,826 1,754 521
Propellant, Kg 15,180 1,903 1,903 777
Initial, Kg 23,150 5,729 3,657 1,299
Isp, sec 290.21 289.40 289.40 287.25
Delivered DV, m/s 3,035 1,146 2,085 2,571
Total Delivered DV, m/s 8,837
Vcirc @ 875 Km, m/s 7,413
DV Losses, m/s 1,424
Now, turn the “Final” and “Initial” mass cells into formulas (“Final” = “Payload + Inert” for each stage, “Initial” = “Final + Propellant”)
Next, turn the “Delivered DV” cells into formulas with the rocket equation in them: DV =9.8 * Isp * LN(Initial/Final)
Don’t forget also to replace the Total DV cell with the sum of each stage’s DV (“S2/BF” = stage 2 burn before fairing sep, “S2/AF” = after staging sep. I arbitrarily assumed the fairing is kicked off halfway into the S2 burn).
You will know you have the correct formulas when your numbers match mine.
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antonioe
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« Reply #14 on: 08/20/2006 01:49 AM » |
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Answer, Part II:
Now do this: reduce the S1 inert by 454 Kg (1,000 lb), and lower the payload to 249 Kg. You should get a delivered DV of 9,414 m/s, which is 1,270 f/s more than the baseline Pegasus flight (770 from the aircraft groundspeed which you don't get if you fire vertically, about 500 from conservatively estimated increased gravity losses):
S1 S2/BF S2/AF S3
Payload, Kg 5,637 3,565 1,207 249
Inert, Kg 1,787 169 455 180
Final, Kg 7,424 3,734 1,662 430
Propellant, Kg 15,180 1,903 1,903 777
Initial, Kg 22,604 5,637 3,565 1,207
Isp, sec 290.21 289.40 289.40 287.25
Delivered DV, m/s 3,169 1,169 2,166 2,911
Total Delivered DV, m/s 9,414
Vcirc @ 875 Km, m/s 7,413
DV Losses, m/s 2,001
This is what a wingless, air-launched Pegasus would do. So, getting rid of the wing saves 1,000 lbs of S1 mass, but the net result is a reduction in payload from 341 Kg to 211 Kg. Gets worse if you ground-launch it (pressure losses; try reducing the payload further to achieve an additional 1,000 fps or so;)
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