Excellent. I'm slowly but surely learning about gravity losses and suborbital manoeuvers because I'm a staunch believer in suborbital refueling as a "4th way" of solving the RLV / SSTO / TSTO conundrum (the other three being : VentureStar, X-30 Orient Express, and Skylon - respectively: all rocket, scramjet, and siphon-out-some-atmospheric-air)
...and now for something completely different... Mind you, I have a little feud with LAR the moderator and for a brief instant I mistook your pseudo for him, which led to some serious head scratching on my side. I tend to mistook you two, LAR and LAR-S-J, don't ask me why.
As for hydrogen peroxide at airports... I can understand the FAA blow a fuse about it. The rocketplanes push back from the gate like ordinary airliners, loaded only with kerosene. They taxi to the end of the runway or a remote, secured area. There - and only there - the oxidizer tank is filled with H2O2 thanks to a pair of trucks stationned there. A pair of 43 mt trucks with H2O2 trailers. could that work from a safety regulation point of view ?
A couple of papers I wrote and hope to get published.
Thrust is a vector quantity, and the direction of the thrust has a large impact on the size of gravity losses. For instance, gravity drag on a rocket of mass m would reduce a 3mg thrust directed upward to an acceleration of 2g. However, the same 3mg thrust could be directed at such an angle that it had a 1mg upward component, completely canceled by gravity, and a horizontal component of mg× 3 2 − 1 2 {\displaystyle {\sqrt {3^{2}-1^{2}}}} {\displaystyle {\sqrt {3^{2}-1^{2}}}} = 2.8mg (by Pythagoras' theorem), achieving a 2.8g horizontal acceleration.As orbital speeds are approached, vertical thrust can be reduced as centrifugal force (in the rotating frame of reference around the center of the Earth) counteracts a large proportion of the gravitation force on the rocket, and more of the thrust can be used to accelerate.
(Zubrin - The hypersonic skyhook - Analog, 1993 and JBIS, 1995) "Only suborbital flight up to Mach 15 would be needed. (...) The TAV would match speeds with the Skyhook bottom, which is hanging at an altitude outside the tangible atmosphere. It would use vertical thrusters to negate gravity during the period of rendezvous. The TAV would hover below the tether tip, open its cargo bay and allow its payload to be hooked by a cable car mechanism. Assuming that 30 seconds of thrust-negated gravity are required for the hooking operation, and that hydrolox thruster with a specific impulse of 450 seconds are used, an amount of propellant whose mass is about 3.3 % of the TAV vehicle will have to be expanded during rendezvous.“
Ok You hit the nail on its head. gravity losses is the trickier part. I'm documenting on that. Case 1 10 m/s lost. In this case we agree that 120 seconds of refueling (2 minutes) would be a penalty of 1200 m/s. ....I need feedback about the above point because, indeed, it is key to the concept.
The attached file features a detailed weight breakdown of the Shuttle orbiter, and also of a derived LH2, air launched SSTO. Also attached are Black Horse, Black colt, and Skylon weight breakdowns.
