HI Folks,
E G David Andrews, Bristol Aircraft Company. 1960
(1) An equatorial trajectory makes it easier to place satellites into orbit in the plane of the ecliptic; and the easterly launch makes it possible to launch "stationary" GSO satellites efficiently.
(2) An equatorial launch provides the maximum initial velocity (1,500ft/sec) for a vehicle launched in an easterly direction.
(3) The low atmospheric pressure at 17,000ft causes the specific impulse of the rocket engine to be increased at launch by about six per cent.
(4) The improvement in specific impulse enables an increased launch weight to be used without corresponding increase in engine weight, hence increasing the mass ratio of the vehicle by nearly the same amount.
(5) The low density of the atmosphere results in lower aerodynamic drag during the initial phases of the launch. "Compared with an equatorial sea level site, the gain could be worth about l,5OOft/sec. Although this does not sound very high it corresponds to an increase in payload of between 20 and 30 per cent, depending on the conditions.
(For the launch of a manned expedition to the Moon this could be worth £5m per shot. The only known technical disadvantage is that the launch trajectory passes through the deepest section of the Van Allen belt.")
Open to correction,
Change from polar to equatorial oribit ( x 1.3 gain) and high altitude (x 1.3 gain ) launch assuming David was correct about the above and the Black Arrow developments took place..
1. CRYOGENIC UPRATED BLACK ARROW 360 n.mile Polar circular orbit A.U.W. 49,210LB PAYLOAD 893 LB ( 1.3 x 1.3 = 1,500lb ) (1,000lb plus to GSO note Black Arrow was to test ion drive vehicle)
2. Standard Black Arrow 300 n.mile Polar circular orbit A.U.W. 40,000LB Payload 232LB. (1.3 x 1.3 = 390lb )
3. UPRATED BLACK ARROW 300 n.mile Polar circular orbit A.U.W. 48,710LB PAYLOAD 375LB (1.3 x 1.3 = 633lb )
4. CRYOGENIC BLACK ARROW 300 n.mile Polar circular orbit A.U.W. 40,000LB PAYLOAD 645 LB ( 1.3 x 1.3 = 1,090lb )
