2009/03/31

"UAVs can sustain higher G loads than pilots". Really?

.
One of the arguments for UAVs (unmanned aerial vehicles - and no, I won't convert to UAS!) is that they aren't limited by the human body' ability to withstand high accelerations (being pressed into one direction when turning rapidly).
Untrained humans can sustain an acceleration of up to about 6g till black-out (1g = the strength of gravity).
Trained pilots with normal G suits can sustain 9g and fighters have been designed to exploit this since the early 70's.

One trick to ease high g load turns is to have the body horizontal instead of vertical - the prone position helps a lot. The practical consequence of this discovery is still visible in the sloped seats of the F-16, for example.

Unmanned airframes could be built to fly 12g turns. Even higher accelerations would likely also be possible, but the demands rise extremely, especially with long wingspans. Missiles with minimal wingspans cane fly more than 40g turns.

A fighter UAV that substitutes for a real fighter would probably be limited to 12-15g.

That's where I'd like to throw the Swiss-German development "Libelle" (dragonfly) into the arena: A revolutionary G suit that enables 11-12 g turns instead of 9g turns for manned fighters.
It works with water, unlike normal, pneumatic G suits.


The human body can sustain much higher g loads if surrounded by water (which cannot be compressed much and is the same as most of our body). A cockpit full of water was always impractical, and a full water suit as well - the Libelle suit limits the water to the minimum to achieve a great effect. The limit of pilots with a custom-made Libelle suit is more like 11-12g than 9g. Normal breathing is possible till 10g. Actions that usually become impossible long before the limit of 9g are possible at much higher accelerations (like up to 10g instead of up to 7g) in that suit. That's certainly the main advantage of the suit in today's fighters.

A normal fighter turned into a drone cannot turn at 9g due to structural limits, manned and unmanned aircraft of new design can be flown at up to 11-12g - the drones only rule beyond 12g, not beyond 9g as many people assert.

The utility of maneuvers beyond 12g is questionable, though. High acceleration turns were historically and still are primarily defensive maneuvers (unlike the Top Gun movie nonsense tells us). 12g might be more than enough to dodge modern missiles - which need to withstand even more extreme accelerations than their target does to hit.

Sven Ortmann
.

3 comments:

  1. Gravity aside, UAVs are cheap. I don't know what it is now, but in the late 1990s about 2/3s of the cost and 1/3 of the weight was devoted to pilot sustainability. The other important factor for UAVs is because of a lack of gravity your average geek can defeat a manned aircraft in air to air combat while eating Doritos and a snickers bar.

    ReplyDelete
  2. Not really. A rule of thumb was that 60% of the costs were avionics costs - mostly all those limited edition black boxes and the radar.

    An ejection seat weights less than 150 kg, breathing equipment maybe 50 kg, pressurized cabin and glass a lot more, but overall pilot sustainment weight should be much less than a ton (in a fighter).

    I don't buy into the "air combat is too complex for computers" slogan of the air forces.

    Today's air combat requires pilots who develop tactics, even within hours. They need to understand their and the opposing hardware as well as a lot of physics stuff.

    It takes a lot of training to think in 3D.
    Most players who use fighter simulations on computers merely use medium range missiles and in close combat they turn, turn, turn. 3D maneuvering is much more complex.

    ReplyDelete
  3. OK, sounds like humans will be able to handle a lot more g with continuous development of suits, so it's questionable that UAVs can become numerous equivalent fighter aircrafts. But I would count on having a double, single and no seat configuration of future fighter aircrafts. A few no-seat fighters, UAVs, allow for much improved capabilities through human (pilot aces) reinforcements during a dangerous engagement. The problem is that the connection can be hacked or jammed and especially hacking can turn this system very dangerous. One precaution against such hacking can be no direct information transfer to the UAV, but short range buddy to buddy data transfer using if possible different codes and more than one buddy for the transfer. I'm not sure, but the US spy plane crash in China could in theory have been due to such an unmanned fighter.
    Another possibility derived from the UAV can be to back up each man in a plane by a team instead of the lone weapon systems officer in the back seat of old. Such a team could in theory include a much better pilot, so the pilot on board not necessarily navigates his aircraft in combat, but solves other tasks and is the manned back-up against any successful hacking. That would be for sure a very strange thing from today's pilot's perspective.
    But just imagine a case like WWII Japan. If they could have kept their diminishing number of trained military pilots in safety for directing combat from far away, less trained pilots could have operated the aircrafts until meeting an engagement that exceeded their skills. Under these circumstances the trained military pilots take over control. This can be seen as an improved way of armouring the pilots seat, as the Americans did that helped them to build up a trained force.

    But why always presume that a useful fighter UAV needs all the ecpensive avionics? Can't it be a small wingman if it uses imitation and very high g maneuvers to guide enemy missiles away from the manned aircraft (like helicopters protected ships during the Falkland War). Now give it some own missile capability to help the pilot in the manned aircraft win any dogfight by ordering his personally programmed wingman to outmaneuver and shoot the enemy based on data mostly transmitted from the manned aircraft with the much more expensive avionics suit.

    ReplyDelete

Use a nickname and stick to it! I may block anonymous comments. Offensive comments may also be blocked, in part due to the duties of a blogger in Germany.