Q&A: Pegasus Designer Dr. Antonio Elias

• #60 by hop on 02 Sep, 2006 22:13
• They don't look that similar to me. If you are building a custom airlaunch vehicle it makes sense to suspend the payload in the middle, which dictates some kind of outriggers for the landing gear.
  
  Another take on the idea: http://www.buran.ru/htm/mol-1000.htm
• #61 by meiza on 03 Sep, 2006 12:31
• And then there's http://www.luft46.com/db/dbbombc.html. Look at the wing shape from the front.
• #62 by sbt on 03 Sep, 2006 15:25
• 
  Yes, these illustrations had me thinking of the M-1000 as well.
  
  BTW, the reason Marshalls had the skills to modify Tristars is that one of the last operators is the Royal Air Force (In the Transport and Air Tanker roles) and Marshalls do their mods and, IIRC, deep maintenance.
  
  http://www.raf.mod.uk/equipment/tristar.html
  
  Rick
• #63 by antonioe on 04 Sep, 2006 01:35
• Quote

  aero313 - 2/9/2006  8:53 AM
  
  

  Quote

  antonioe - 31/8/2006  12:46 PM
  
  

  I answered "120,000 lb" - hence the name "Castor 120", later renamed to "GT-120".  (Frankly, perhaps the Lockheed people also told him 120,000 lb - great minds think alike.)

  
  Sorry, Antonio, but the sizing of the Castor 120 was a function of using the existing production facilities that Thiokol already had in place (and that had been paid for by the Air Force) for the PK first stage.  The 120 uses the existing casting pit, case winding machine, and handling tooling as the PK motor.  Anything much larger than the current 120 would have required a significant additional investment on the part of Thiokol (who admittedly invested over $30M in the development of the 120 as it is).

  
  Well, the diameter was quite set, but the length (therefore the gross mass) could be moused up or down by quite a bit.  I just remember the phone call (can't remember WHO it was that called, thought.  Thiokol was a competitor to Hercules at the time.)
• #64 by David AF on 04 Sep, 2006 19:36
• Really enjoying the stories.
  
  On the Pegasus, I noticed during the coverage on here of ST5 that the vehicle appears to have a very good RCS system, orinating several times for each of the three deployments. Is this system adopted from another other vehicle?
• #65 by antonioe on 04 Sep, 2006 20:08
• Quote

  David AF - 4/9/2006  2:23 PM
  
  Really enjoying the stories.
  
  On the Pegasus, I noticed during the coverage on here of ST5 that the vehicle appears to have a very good RCS system, orinating several times for each of the three deployments. Is this system adopted from another other vehicle?

  
  No, it's just a bunch of little solenoid-controlled cold gas jets.  I can't remember if the valves had any ancestry (I'll ask around if anybody remebers and report back).  Other than cleverly being able to adapt to large longitudinal changes in CG location, (i.e., software) I don't think the Pegasus RCS system is particularly noteworthy.
  
  On Flight 2, we reoriented seven times, one for each of the 25- kg DARPA Miscrosats (not to be confused with the 43-kg ORBCOMM MicroStars, the way www.astronautix, unfortunately, did).
• #66 by Terry Rocket on 23 Sep, 2006 22:34
• In the film Under Siege 2 with Steve Segal, the guys at the Pentagon needed to "shoot down" a rouge satellite that had come under the control of the usual madman type in the film. They mentioned that they could air launch a Pegasus to take it out.
  
  Now you don't really get to see it, but it looks a bit like the right size, although it seems to be launches by a Stealth Bomber, but could Pegasus be used that way?!?
  
  I know it's Hollywood, but worth asking, and they certainly said Pegasus!
• #67 by Carl G on 25 Sep, 2006 00:04
• I can't think of a need to take out a satellite.
• #68 by antonioe on 25 Sep, 2006 00:15
• Didn't see the movie... did they really call it a "Pegasus"?  I know Dale Brown ("Flight of the Intruder") wrote a book with a fictional "hero" somwhat between David W. Thompson and Elan Musk (by the way, years before the latter entered the space entrepreneurial arena - I guess Dale is a clairvoyant) and featuring an airline-dropped launch vehicle... can't quite remember the title of the book.
  
  As for "why would anybody want to take out a satellite", I certainly don't see a need for *US* taking out an enemy satellite (although the idea for Pegasus was indeed seeded by the U.S. ASAT test)... I would rather worry about *OTHERS* taking out *OUR* satellites... *WE* are more dependent on our sats that any adversary could be on theirs - well, actuallky I think many of our current adversaries could very well be dependent on *OUR* (or friendly nation's) sats for nav and com!!!
  
  I've been a bit busy these days with CEV and the like... I will resume the "brief history of Pegasus" as soon as I can.  At some point. I'd like to post a list I put together around 1993 or so listing the design elements of Pegasus that did and did not make it into the final design...it's, as Mr. Spock would say, "fascinating"...
• #69 by Chris Bergin on 25 Sep, 2006 00:29
• Quote

  antonioe - 25/9/2006  12:58 AM
  
  Didn't see the movie... did they really call it a "Pegasus"?

  
  
  I've seen this film and they certainly do call it a Pegasus. Looked more like an oversized AGM-129 Advanced Cruise Missile (thanks Google) off a B-2 Stealth. From memory it didn't seem to be big enough to represent a real Pegasus, but it was a while ago since I've seen that film. Usual Hollywood goings on with the fireball in space and the *boom* noise
  
  

  Quote

  I've been a bit busy these days with CEV and the like... I will resume the "brief history of Pegasus" as soon as I can.  At some point. I'd like to post a list I put together around 1993 or so listing the design elements of Pegasus that did and did not make it into the final design...it's, as Mr. Spock would say, "fascinating"...

  
  Excellent. Had a lot of PMs asking where the good Dr has been with his next installment!
• #70 by Terry Rocket on 25 Sep, 2006 13:38
• Sure was the Pegasus by name!
• #71 by TyMoore on 25 Sep, 2006 14:45
• I would imagine that any vehicle capable of lofting a payload to the same height as a satellite could be used to deliver a hit-to-kill device. Pegasus obviously is capable of delivering a significant payload to orbit--so a suborbital kinetic kill vehicle is not out of the question. I would imagine that it is primarily a sensor, trajectory prediction, attitude correction problem--not insurmountable, just difficult. The range rate is the tricky thing--getting the launch aircraft into the correct launch window (which is very, very narrow!) is the really hard part. That, and creating a smart interceptor that has the required tracking telescope/radar device, RCS thrusters and propellant quantity, and an onboard computer and command and control telemetry that can integrate all the data together in real time--its a tall order, but I'd bet there are some SDI prototypes on a shelf somewhere that could do the job. And they're certainly small enough to be lofted by Pegasus.
  
  By the way, Pegasus is a nifty bit of rocket engineering. Kudos to you, Dr. Elias!
  
• #72 by Jim on 25 Sep, 2006 14:59
• This has already been done with the air launched ASAT that flew on an F-15, which the Pegasus was derived from
• #73 by antonioe on 26 Sep, 2006 03:20

• Well, perhaps to say that Pegasus was derived from the LTV ASAT is carrying the analogy a bit too far (the two vehicles are vastly different in size, number of stages, delivered DV, avionics, RCS, etc.)    It is true, though, that the idea of an air-launched orbital rocket came to me after reminiscing of the ASAT test.  Interestingly, there is an LTV ASAT and a Pegasus next to each other at the Smithsonian Udvar-Hazy museum - I wonder how many visitors realize the connection; also, the hotel where the Pegasus-genearating "booring meeting" took place is ACROSS THE STREET from the Udvar-Hazy!!!)

  That said, Pegasus - or, for a matter of fact, any orbital launch vehicle - is a vast overkill as a weapon against a LOW ORBITING satellite.  Air-launch does simplify the intercept problem a bit, since you can reduce, by smartly flying the carrier aircraft, the cross range that the ASAT missile might to cover to kill a satellite on a given pass.

  Killing a high-altitude satellite (a GEO, for example) is a different matter.  Here. merely climbing to the orbital altitude and essentially "getting hit" by the satellite (à la 1985 test) won't work.  You have to enter a Hohmanesque transfer and hit the satellite with the difference between the sat's circular velocity and the interceptor's (lower) apogee velocity.  In other words, the interceptor has itself to be a satellite with several hour's (as opposed to minutes) operating life, and you need a launch vehicle to launch the interceptor...

• #74 by meiza on 26 Sep, 2006 11:39
• One stranger question.
  
  Did you ever think about making the Pegasus first stage reusable? It already has wings, but how does the first stage actually behave now after staging?
  Reusability would have probably meant liquid pressure-fed first stage and launch from a specific site so you can land / ditch it in an appropriate place. But it'd be cheap to operate, just reloading the propellants.
• #75 by Pete at Edwards on 28 Sep, 2006 03:08
• How does Pegasus/Orbital stack up against Falcon/SpaceX on cost per lb right now? I am taking into account that SpaceX is unproven as of yet.
• #76 by antonioe on 03 Oct, 2006 23:30
• Alas!  Space launch is not a commodity yet - so, like buying a car, you must be very careful to call out what "accessories" are (or are not) included.  Do you want Range Safety with that launch?  How about telemetry all the way to spacecraft separation? (that can add quite a few $$$s...)  Will you take care of FAA launch permits, or shall we do it for you?  Is it the same orbit you flew to last month, or do you want us to calculate a new launch trajectory (inclusive of stage drop points, range safety lines, etc.)  Do you want a coupled modes analysis with your spacecraft, or will you take your chances?  Do you need any mods to the fairing, like access doors, RF transparent windows, or special "bumps" into the dynamic envelope?  Venting for you solid hydrogen cooler? How about data passthroughs from the spacecraft to your ground support equipment while waiting for launch? Collision avoidance maneuver?  Would you like a specific sun-relative spin at release (that depends on the exact time of launch, by the way...) And so on and so forth...  each little thingy costs a few hundred K$'s but it soon adds up.  Makes real launch vehicles look more expensive than paper ones.

   

  Like cars, you can buy a basic model, or you can buy a "loaded" one.  Current real customers simply don't buy stripped-down launches.  Apparently, when they spend $50M for a satellite bus, $50M for scientific instruments, and another $50M for the science mission, it simply does not seem balanced to skimp too much on the launch.  Same logic applies to commercial comm sats (when it comes to mission assurance and the like, SES/Americom makes JPL look like a bunch of Vegas gamblers).

   

  Are there any Yugo customers?  I don't think so.  So before you compare dollars per pound, make sure you are including the same elements on both sides of the ledger.  And you can't just say "well, the customer does not need all that useless stuff".  They do.  They want it.  The customer is always right.  If you don't offer them those "thingies", they will not buy a launch from you.  At least not the customers with money.  I've been there.

   

• #77 by vt_hokie on 04 Oct, 2006 00:00
• A very interesting explanation once again!  A few hundred thousand here and there, and soon you're talking about real money!  
• #78 by NASA_Twix_JSC on 04 Oct, 2006 00:04
• Quote

  antonioe - 3/10/2006  6:13 PM
  
  Alas!  Space launch is not a commodity yet - so, like buying a car, you must be very careful to call out what "accessories" are (or are not) included.  Do you want Range Safety with that launch?  How about telemetry all the way to spacecraft separation? (that can add quite a few $$$s...)  Will you take care of FAA launch permits, or shall we do it for you?  Is it the same orbit you flew to last month, or do you want us to calculate a new launch trajectory (inclusive of stage drop points, range safety lines, etc.)  Do you want a coupled modes analysis with your spacecraft, or will you take your chances?  Do you need any mods to the fairing, like access doors, RF transparent windows, or special "bumps" into the dynamic envelope?  Venting for you solid hydrogen cooler? How about data passthroughs from the spacecraft to your ground support equipment while waiting for launch? Collision avoidance maneuver?  Would you like a specific sun-relative spin at release (that depends on the exact time of launch, by the way...) And so on and so forth...  each little thingy costs a few hundred K$'s but it soon adds up.  Makes real launch vehicles look more expensive than paper ones.

  Like cars, you can buy a basic model, or you can buy a "loaded" one.  Current real customers simply don't buy stripped-down launches.  Apparently, when they spend $50M for a satellite bus, $50M for scientific instruments, and another $50M for the science mission, it simply does not seem balanced to skimp too much on the launch.  Same logic applies to commercial comm sats (when it comes to mission assurance and the like, SES/Americom makes JPL look like a bunch of Vegas gamblers).

  Are there any Yugo customers?  I don't think so.  So before you compare dollars per pound, make sure you are including the same elements on both sides of the ledger.  And you can't just say "well, the customer does not need all that useless stuff".  They do.  They want it.  The customer is always right.  If you don't offer them those "thingies", they will not buy a launch from you.  At least not the customers with money.  I've been there.

  
  That's a brilliant explanation.
• #79 by braddock on 05 Oct, 2006 18:38
• I must say, I was rather hoping for an equally sophisticated answer from Musk when I asked him about some of these "extra" costs in one of the interviews.
  He insisted that the Falcon quoted prices were "all inclusive"...mostly.  The range fees had been higher than expected; they had developed some "non-trivial" small satellite analysis capability; but he only seemed to talk about what they had encountered so far.
  
  Musk: "But if someone has sort of a normal satellite, and it doesn't have any special requirements, and isn't gonna put a mission assurance process burden on the launch, then it's an all inclusive price."
  
  http://www.nasaspaceflight.com/content/?cid=4705