Do We Need Aerial Tankers?

Do we really need carrier based, aerial tankers?  Your immediate reaction is, of course we do!  However, let’s hold off before we make that our final answer and take a moment to look just a bit closer at the tanker question.
 
Let’s start by answering the most basic question:  why do we have tankers, currently?  This is not a trick question.  There are two general answers:
 

• Overhead Tanking provides tanking for overhead aircraft who need a just a bit of extra fuel to get back aboard the carrier.  Perhaps the pilot had to execute one too many wave offs and go-arounds and has run just a bit low on fuel or maybe the aircraft came back from the mission low on fuel due to any number of possible reasons.  Those aircraft need fuel.
• Mission Tanking extends the reach of a mission.  WWII aircraft were limited to a range of whatever their onboard fuel tank allowed them.  Tanking is a means of extending the range of an aircraft by refueling during the mission.

 
Understanding those two basic requirements, let’s look a bit deeper and bit further into the future of tanking.
 
 
Mission Tanking
 
Let’s start with the mission extension requirement.
 
Here’s a question you may not have previously considered:  what determines the maximum range of a mission?
 
Simplistically, the range is determined by the aircraft’s unrefueled range plus any aerial refueling provided as part of the mission … but is that the whole story?  Since we’re doing a post on this, you can assume it’s not!
 
If fuel were the only determinant of range, we could, in theory, have carrier aircraft fly global missions.  The carriers could stay in port, launch aircraft, and those aircraft could strike/fight on the other side of the world;  after all, it’s just a matter of sufficient refueling events, right?  However, a moment’s thought suggests that the pilot of a single seat aircraft can’t remain awake, alert, and combat effective beyond a certain number of hours in the cockpit.  Anyone who’s driven long hours in a car understands the debilitating effect of cramped quarters even with occasional pit stops for relief, food, rest, and just to stretch one’s legs.  How much worse must it be for a pilot who, literally, is strapped in and can’t move or stretch, and struggles even to relieve himself.  At some point, the pilot becomes combat ineffective.  It’s analogous to the infantryman who quickly becomes ineffective in a landing craft due to seasickness after a brief period.
 
What is the time period beyond which a pilot becomes combat ineffective?  I don’t know – and it will vary somewhat from person to person – but a reasonable estimate is around three hours.  Beyond that point, the pilot begins to lose effectiveness.  Sure, there’s nothing like the adrenalin surge of combat to wake one up but there’s no escaping the underlying decrease in alertness, reflexes, and mental agility (which declines precipitously with fatigue).  A less than completely optimal pilot is another way to describe a dead pilot.  This is not to say that a mission longer than three hours can’t be accomplished but you’re dipping into diminishing returns at that point.  Diminishing returns is another way to describe a dead pilot and failed mission.  Modern combat requires 100% efficiency in order to have a hope of survival and success.  This, by the way, is the main reason why modular ships are inherent failures – they’re not 100% optimized.  But, I digress …
 
Let’s set aside range limitations and consider enemy threats.  Submarines, cruise and ballistic missiles, supersonic aircraft, very long range SAMs, and the like have resulted in being forced to doctrinally move our carriers further and further back from the target.  We’re now talking about having to operate many hundreds of miles away or even out to a thousand miles or more.  What does that do to the mission time frame?  Using subsonic aircraft with, say, a cruise speed of 550 mph, it would take 3.6 hours to fly a thousand mile, straight, out and back mission.  Now, throw in realistic time delays for departure assembly at the carrier, tanking, non-linear routes, in-flight refueling, actual mission execution time (air to air combat or loitering), landing pattern time, etc. and that bare minimum of 3.6 hours becomes something on the order of five hours.  Wait … what did we say about cockpit time beyond which a pilot’s performance begins to degrade?  Yeah, something on the order of three hours.  Uh, oh …
 
Returning now to the tanker issue, we can see that simply adding tankers to provide longer and longer ranges is not a correct or viable approach.  Tanking is beneficial only until it extends the mission time beyond the magic three hour limit.  After that, it becomes counterproductive.  Thus, even if we had a tanker that could deliver infinite fuel at infinite range, it would be useful only within fairly narrow constraints. 
 
The pilot’s combat effectiveness is the limiting factor, not fuel !
 
Thus, bigger, better, longer ranged tankers are not the answer beyond a certain point.
 
Note:  An almost semantic variation of the range extending, mission tanking is station time extension where we want to keep an aircraft on station for an extended time at a shorter range.  For example, an aircraft flying cap at, say, 300 miles, might need refueling to enable it to loiter on station for a couple hours even though it has sufficient onboard fuel for the 600 mile round trip.
 
 
Overhead Tanking
 
Not much to say about this.  Overhead/recovery tanking is a mandatory aspect of carrier operations.  There’s no getting around the need.
 
 
Conclusion
 
Single seat aircraft are constrained by the physical and mental fatigue limits of the pilot.  As we noted, a thousand mile mission is about the limit of a pilot’s combat effectiveness.  Thus, our attempts to design and build aircraft with combat radii greater than a thousand miles and/or to provide tankers that can extend missions beyond a thousand miles are pointless.
 
Of course, if our aircraft have only an inherent combat radius of, say, 200 miles then, yes, we need to provide tanking to accomplish a thousand mile mission.  However, we have, in the past, built aircraft with unrefueled, thousand mile radii, or nearly so, so that should be our design goal.  An aircraft with a thousand mile unrefueled radius pretty much eliminates the need for mission tanking except in the extreme of, say, maximum range, air-to-air combat which requires full power/afterburner once arriving on station.
 
The conclusion is that, yes, we most definitely need tanker aircraft but we need to be careful to recognize that we’re bumping up against pilot limitations, not fuel limitations.  This recognition should impact our tanker needs (number, size, capacity, etc.) and design.
 
 
 
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Note:  I selected a value of three hours as the point beyond which a pilot becomes ineffective.  It could be two hours, or four, or 3.187.  The exact value doesn’t change the premise and there is no exact value, anyway, since it would vary from pilot to pilot and would depend, in part, on the circumstances of the mission.  Therefore, I’m not going to entertain debates about the exact value.  Fair warning!