What are current rates like for the air transport of cargo? I'm wondering about ways for the Stratolaunch carrier to make money when not being used for launch, a little like how the Zero-G aircraft gets used for cargo flights.
Would it be impossible to attach wings and landing gear + some airbus or boeing jet engines to Falcon 9 (or Falcon 4/5) first stage? You would get reusable Falcon rocket that Elon desires and air lauch at the same time. If that's possible I'd like to see Paul Allen investing his money to that rather than Stratolaunch.
I have a question: is this Stratolaunch carrier craft sized for future growth of the rocket diameter-wise? It seems to me as if it is.
Quote from: Robotbeat on 12/16/2011 07:22 pmI have a question: is this Stratolaunch carrier craft sized for future growth of the rocket diameter-wise? It seems to me as if it is.Doubt it. I'd expect the baseline booster to pretty much max out the payload of the aircraft. That's certainly the impression I got from the press conference. No need for a significantly bigger diameter booster unless they switch to LH2, which seems unlikely.From the renderings, I don't really get the impression it's oversized, there's plenty of width but in the ground clearance looks fairly tight (though perhaps the attachment point on the wing could be more svelt.) In any case, it's probably not safe to assume the renderings reflect the actual design in great detail.
Quote from: baddux on 12/16/2011 07:48 pmWould it be impossible to attach wings and landing gear + some airbus or boeing jet engines to Falcon 9 (or Falcon 4/5) first stage? You would get reusable Falcon rocket that Elon desires and air lauch at the same time. If that's possible I'd like to see Paul Allen investing his money to that rather than Stratolaunch.See link here:http://forum.nasaspaceflight.com/index.php?topic=27477.0
Methane would be about 20% more volume than RP-1? I wonder if that could be enough difference to be a clue WRT the rendering length. We know dragon and trunk dimensions pretty well. We know the likely diameter...
Well you "kinda" answered your own question Norm38, as the "zoom" (pitch-up) IS required in one form or another to get the rocket to the proper gamma for release.
Quote from: Lee Jay on 12/16/2011 01:27 pmQuote from: RanulfC on 12/16/2011 01:19 pmSince you need to have a thrust to weight ratior of over 1.0 when performing the pitch-up manuver (to avoid stalling)...No you don't. You carry energy in the form of inertia. This is why even gliders can do vertical maneuvers.True, I just didn't want to get into that much detail Vertical maneuvers bleed energy at a VERY fast rate that's why you don't see gliders performing "zoom-climb" manuevers Without a form of thrust capable of equaling the force of gravity you can't maintain the required angle for more than a few seconds before your wings stall. This is "worse" for a heavily loaded aircraft, especially at high altitude.
Quote from: RanulfC on 12/16/2011 01:19 pmSince you need to have a thrust to weight ratior of over 1.0 when performing the pitch-up manuver (to avoid stalling)...No you don't. You carry energy in the form of inertia. This is why even gliders can do vertical maneuvers.
Since you need to have a thrust to weight ratior of over 1.0 when performing the pitch-up manuver (to avoid stalling)...
Ugh, now that I think of it the problem gets worse once you release the rocket! If you were using the rockets motors to both check them out and to provide the needed thrust for the "zoom" you lose that as soon as you release AND what lift you have it now pushing you to a HIGHER Angle-of-Attack!
So, when you release the rocket, things get way, way better because you keep the same thrust and lose half your mass.
Quote from: Lee Jay on 12/16/2011 10:26 pm So, when you release the rocket, things get way, way better because you keep the same thrust and lose half your mass.I actually think that phase is really hairy, because when you release the rocket, you have the same lift, and loose half your mass. Think about that for a few minutes...The airframe is going to see significant Gs in that period, and you don't easily change the lift that the aircraft is generating very quickly- particularly since the carrier aircraft will also be taking evasive actions to get out of the thrust centerline of the now-launched rocket.
I seriously doubt the idea of using the main rockets while attached to the plane. So, when you release the rocket, things get way, way better because you keep the same thrust and lose half your mass.
In 2005 we flew belly drops from the 747, using the NASA 747 simulator at Ames. We were dropping 209K lbm, or about the same payload to gross mass ratio of the system under debate. The maneuver went extraordinarily smoothly, and could be flown even by low-time pilots. Like me – I had six hours at the time. We also determined that clearing turns were not really required for air-launching, if you do it right. There's a bunch of t/LAD papers out there that explain what "right" is.