"Ballistic phase" and "runway in the sky" -- I dunno about that. "Runway in the sky" sounds like public relations aimed at passengers.
A ballistic projectile is an object initially projected upward in a gravitational field which cannot develop enough lift to significantly depart from a parabolic trajectory. A Medieval catapult throws stones into a ballistic trajectory.
"Transiently developing insufficient lift" might be a more accurately describe a Harrier's state shortly after departing the ramp. All right, if you insist, we can could call that a "ballistic phase."
One's Harrier needs to take off with as much kinetic energy as possible. Climbing the ramp makes the airplane lose some kinetic energy, compared to a Harrier takeoff roll for a distance equal to same ski jump approach deck run plus ramp length lowered to horizontal.
A Medieval catapult throws stones into a ballistic trajectory by transferring kinetic energy to the stones. A ramp for Harrier takeoffs is not a catapult. The Harrier loses some k.e. as the Harrier climbs the ramp.
Pitching the aircraft up roughly ten degrees relative to any wind over deck also increases form drag and skin drag slightly. Also, the airplane's momentum increases weight on wheels and therefore rolling resistance during the climb up the ramp.
If the goal is only to have as much kinetic energy as possible just after weight is no longer on wheels, one is better off taking off from a horizontal deck with no ramp, assuming the deck is high enough above the sea to allow recovery from an almost stalled condition.
One might also say that the ski jump or ramp trades kinetic energy for potential energy. However, I don't see the point in merely trading p.e. for k.e during Harrier takeoff, if no other benefit is achieved. Following this logic, an improved Invincible class should have had the entire aviation deck raised to the height of the top of the ramp, so as to gain potential energy without sacrificing kinetic energy for a Harrier's ballistic leap onto that runway in the sky.
As far as being higher above the water giving one more time to eject, I'm not sure that that there'd be significant difference in time until water impact, if one has traded (ramp length)*sin( 10 deg) of p.e. for (ramp length )*(cos 10 deg) of k.e., assuming the aircraft is developing some lift in both cases.
Remember, a stalled aircraft does not actually drop like a stone.
Sorry, but I think the ramp helps by pitching up the Harrier's wing to a higher angle of attack and therefore a bigger lift coefficient; a higher aoa than the airplane could achieve without the ramp during takeoff rotation. This rotation to higher aoa compensates for the shorter deck roll allowed by an Invincible-class, even though the ramp takeoff trades away some kinetic energy.
//////////////////
The aircraft isn't actually 'flying' on it's wings until it reaches for example 130+ knots, but that would require a flight deck in excess of 1500 ft in length for some types.
What types are those?
How do AV-8B's operate off 844 foot long WASP-class ships? My supposition is that AV-8B's depart the deck with their wings at a lower angle of attack and therefore with a smaller lift coefficient just after departing the ramp, compared to the aoa of a Harrier II taking off from an Invincible-class. However, the AV-8B is compensated by departing a Wasp's deck after a longer roll and therefore with more kinetic energy for that "ballistic phase" and "runway in the sky."
The ski jump cleverly and smartly compensates for a shorter deck roll.
Last edited by Modern Elmo; 25th Jul 2011 at 04:35.