The downing of Trudy's Samson

[AC130StandingBy]

I've noticed something odd about the destruction of Trudy's Samson. As you know, modern helicopters that have tail rotors can be taken down by damaging the tail rotor of the aircraft because the reactive torque of spinning the rotor causes the aircraft to spiral out of control (lucky shots to the tail rotor caused the shootdowns of two MH-60L Blackhawk helicopters in Somalia in 1993). However, the tilt-rotors of the helicopters in Avatar are coaxial, so that if one of the tilt-rotor fans is destroyed, the helicopter should be able to controllable, provided that the power of the other fan is reduced, and the control surfaces are rearranged to compensate for the asymmetric lift. In the movie, I noticed that when the Dragon’s gatling guns destroyed one of Trudy’s engines, the helicopter began flat-spinning out of control. Since the fan spools coaxial rotors, the helicopter shouldn’t be flat spinning, but rather rolling along its length.

Any physics experts want to take a crack at this? (I will be taking AP Physics starting in fall of 2010, so I haven’t mastered the subject yet)

[Pandora Warrior]

I agree but some of the stuff that happens in movies happen the way they do to add dramatic effect more so than to be realistic.
Trudy, sexiest female on Pandora thats under 10' tall.......

[ScottWashburn]

I seriously doubt that a helicopter designed like that can maintain control with only one set of rotors in action. The side without the working rotors would be pulled downward and the other rotors can't be tilted far enough to achieve a stable orientation (even assuming they could produce sufficient thrust to keep the copter airborne on their own). However, I do agree that the result wouldn't be a spin, it would be a roll as the working rotors pushed the copter over on its side.

Actually, re-reading your post, are you talking about just one of the counter-rotating props going out of action? Each of the copters has four sets of rotors, two on each side. But I'm assuming that each pair is being driven by a single motor so if that motor is damaged, both rotors on that side would lose power.

[StratoNa'vi]

The Samson has at least 2 Turboshafts, you can see the Samson has 2 air intakes and jet exhausts, which definitely means there are two gas turbines on the Samson. Something else to add on, Trudy should be able to manoeuver the Samson out of the line of fire with the single set of rotors.

[electrosphere11]

I've noticed something odd about the destruction of Trudy's Samson. As you know, modern helicopters that have tail rotors can be taken down by damaging the tail rotor of the aircraft because the reactive torque of spinning the rotor causes the aircraft to spiral out of control (lucky shots to the tail rotor caused the shootdowns of two MH-60L Blackhawk helicopters in Somalia in 1993). However, the tilt-rotors of the helicopters in Avatar are coaxial, so that if one of the tilt-rotor fans is destroyed, the helicopter should be able to controllable, provided that the power of the other fan is reduced, and the control surfaces are rearranged to compensate for the asymmetric lift. In the movie, I noticed that when the Dragon’s gatling guns destroyed one of Trudy’s engines, the helicopter began flat-spinning out of control. Since the fan spools coaxial rotors, the helicopter shouldn’t be flat spinning, but rather rolling along its length.

Any physics experts want to take a crack at this? (I will be taking AP Physics starting in fall of 2010, so I haven’t mastered the subject yet)

I would agree with you as well. It would be rolling along its longitudinal axis rather than spinning.

[Eternal Enigma]

The turning mechanisms for this aircraft are the tilt rotors themselves. Applying or reducing power to the rotors is what causes the aircraft to tilt on its horizontal axis. (as an airplane does as it turns) Besides turning the tilt rotors also provide lift, forward momentum, and breaking (with additional fine YAW affects included with tail input... which, in theory makes it very maneuverable) I can only assume the second set of rotors on each side (for the purpose of this movie) would also aid in the stable flight of such a craft. In the event you lost one of your rotary engines you would in no way be able to continue flying this aircraft. Removal of one of the two (complete) tilt rotors (or turbo-shaft) should result in the aircraft destabilizing in an almost barrel roll like fashion. Due to the sudden loss in thrust the result would be immediate flight imbalance off to one side. The craft would turn upside down and nose right into the ground. (vertical axis down “up” with continued horizontal “vertical” thrust would cause the craft to spiral out of control pointing downward as it rapidly descended) Like a plane with one wing.

Depending on the situation or if at a higher altitude the only way to regain any sort of “control” what-so-ever would have to rely on advanced computer controlling and flight stabilization systems. An advanced computer system applying power in varying amounts along with constant axis adjustments would keep you “aloft” in a simi-stable fashion as you went down. In this case the aircraft should go down following an altitude dependant flight path, which is reduced to a circle spiral. User input during this process would most likely result in the craft plummeting from the sky as the stabilization system fought whatever input the pilot made while trying to “save it.” In addition, the twin turbines (jet engines) for this aircraft are most likely used as a “turbo-shaft” so they have no factor in direction as they’re most likely only used for power instead of thrust.

While realism is preferable we really aren’t able to understand how an aircraft like that would really fly especially on a planet with unknown atmospheric conditions like Pandora. Our closest operational version of such a craft (that I’m aware of) is the V-22, best known as the Osprey, which is still not perfected though flight stabilization is much better than when we first saw the Osprey twenty years ago. This half helicopter half airplane hybrid has only become useful in recent years. Due to design flaws and lack of proper flight control stabilization software; in the past this aircraft was famous for its crashes and for killing its crews more than it’s flying ability. I remember the first time I ever saw an Osprey flight demonstration… it was in a news report of the crash.

As for the Samson… In the real world, I doubt it would ever get off the ground. With four sets of blades two on each side rotating in opposing directions... just picturing the wind chop disturbance in my mind makes it seem like it would never work because the blades would cancel each-other out. My guess is it would be a very loud yard ornament.

[Shatnerpossum]

As for the Samson… In the real world, I doubt it would ever get off the ground. With four sets of blades two on each side rotating in opposing directions... just picturing the wind chop disturbance in my mind makes it seem like it would never work because the blades would cancel each-other out. My guess is it would be a very loud yard ornament.

Its nothing but a pair of counter-rotating blades on each side. If counter-rotating was your concern about functionality, then take a look at a lot of Russian helicopters, especially Kamov.

And to the OP: excellent point there. Since the counter rotation is on both sides, there shouldn't be the spin seen with the failure of one side. If there had been only one blade on each side, then it might have been a possibility.

[Eternal Enigma]

Its nothing but a pair of counter-rotating blades on each side. If counter-rotating was your concern about functionality, then take a look at a lot of Russian helicopters, especially Kamov.

And to the OP: excellent point there. Since the counter rotation is on both sides, there shouldn't be the spin seen with the failure of one side. If there had been only one blade on each side, then it might have been a possibility.


I completely forgot about that helicopter. Not to mention the home built feather-light helicopters and smaller remote controlled helicopters like the ones by Air-Hogs. For some reason in my mind opposing blades didn’t seem like they’d work because it seemed like they would end up cancelling each other out by causing too much air disturbance. Obviously I didn’t think about it long enough or I would have remembered these other types of aircraft. Perhaps we’ll see aircraft like the Samson one day after all. So I retract my statement of it only being useful as a loud yard ornament. I still believe I came up with an accurate scenario for how it would operate in the event of engine failure though. Being that the blades aren’t in the center axis a spin would be unlikely even with just one blade. When a twin engine prop plane loses one of its engines it doesn’t suddenly start spinning out of control.

[SnowRider]

If memory serves correctly, James Cameron said they built a scale-model version of the Samson and flew it around the studio parking lot just to see if it would actually fly.

Evidently, it did.

[Shatnerpossum]

I completely forgot about that helicopter. Not to mention the home built feather-light helicopters and smaller remote controlled helicopters like the ones by Air-Hogs. For some reason in my mind opposing blades didn’t seem like they’d work because it seemed like they would end up cancelling each other out by causing too much air disturbance. Obviously I didn’t think about it long enough or I would have remembered these other types of aircraft. Perhaps we’ll see aircraft like the Samson one day after all. So I retract my statement of it only being useful as a loud yard ornament. I still believe I came up with an accurate scenario for how it would operate in the event of engine failure though. Being that the blades aren’t in the center axis a spin would be unlikely even with just one blade. When a twin engine prop plane loses one of its engines it doesn’t suddenly start spinning out of control.

The beauty of a counter-rotating design is that it doesn't transfer torque to the airframe, thats why conventional helicopters have tail rotors. But that rotor is a huge liability, so much as a bump to it on landing will ruin your day real quick.

You did come up with an accurate evaluation of the engine failure though. But the exact term would only apply if it uses two engines. Otherwise it couldn't be considered an engine failure if one rotor quits.

[Scharnvirk]

I am quite sure that the rotor itself was fine, and it was just the engine which was destroyed. The remaining engine could power both rotors... to some extent.