From: egruf_usenet@cox.net   
      
   On 26 Jun 2004 13:41:23 GMT, in sci.space.tech Andrew Gray   
    wrote:   
      
   >On 2004-06-21, Hephaestus  wrote:   
   >>   
   >>>     Assuming a dry mass of 3500kg for SpaceShipTwo, it will have a wet mass   
   >>> of about 26000 kg.  The X-15 weighed around 23,000 kg, so a Black Knight   
   >>> capable of carrying a SpaceShipTwo is certainly not unreasonable to   
   imagine.   
   >   
   >(X-15a was 30kkg, of which 20kkg was propellant, FWIW)   
   >   
   >> But it is the size of a B-52 or larger.  You're either going to have to   
   >> modify something off the shelf of similar size, or build one.  B-52s cost   
   >> ~$75 million, and that's when you buy in bulk.  That's a lot of money just   
   >> for the carrier plane!   
   >   
   >B-52s, being large nuclear-capable bombers, may be slightly   
   >overengineered for a carrier plane role in general... ;-)   
   >   
   >One of the reasons the B-52 was used as a carrier plane, I suspect, was   
   >that it was there and available, rather than that it was needed; if you   
   >can scam a plane off the Air Force for the cost of operations, why   
   >design and build a new one?   
   >   
   >The weapons load for a B-52 seems to be about 31,500kg, handily the mass   
   >of an X-15, but a laden B-52 could also be hauling some 105,000kg of   
   >fuel... and an operational range of Moscow & back is arguably overkill   
   >for a carrier plane.   
   >   
   >Anyway, I had a point here somewhere. Hrm. Whilst building a plane to   
   >carry something the size of an X-15 is a nontrivial task, and it will   
   >end up being large, I don't think the B-52 is an accurate demonstration   
   >of the scale of the problem - a dedicated carrier plane would almost   
   >certainly be significantly more efficient in the role.   
      
   The NASA B-52B has a wing modification done to it to carry the X-15 and   
   pod.  The aircraft will be taken out of service after the Hyper-X Mach 10   
   test flight as it has reached the end of it's service life. Recent   
   estimates of the cost of similar mods to the newer H model ranged from   
   $20-100M, IIRC.   
   ________________________________________________________   
   Ed Ruf    Lifetime AMA# 344007 (Usenet@EdwardG.Ruf.com)   
   http://EdwardGRuf.com   
      
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