2011/6/18 syd adams <adams....@gmail.com>: > My more simple understanding was the actionpoint was the point where > thrust was applied relative to the engine mass , like the > documentation states. > > an <actionpt> subelement > to place the action point of the thrust at a different > position than the mass of the engine. >
Sorry but your interpretation is incorrect. I have extracted below the relevant code that shows that actionpt should be taken relative to the aircraft global origin not relative to the engine position (it actually overwrites the default position which is set at the engine position). src/FDM/YASim/FGFDM.cpp 413: } else if(eq(name, "actionpt")) { 414: v[0] = attrf(a, "x"); 415: v[1] = attrf(a, "y"); 416: v[2] = attrf(a, "z"); 417: ((Thruster*)_currObj)->setPosition(v); src/FDM/YASim/Thruster.cpp 20: void Thruster::getPosition(float* out) 21: { 22: int i; 23: for(i=0; i<3; i++) out[i] = _pos[i]; 24: } 25: 26: void Thruster::setPosition(float* pos) 27: { 28: int i; 29: for(i=0; i<3; i++) _pos[i] = pos[i]; 30: } src/FDM/YASim/Model.cpp 382: for(i=0; i<_thrusters.size(); i++) { 383: Thruster* t = (Thruster*)_thrusters.get(i); 384: float thrust[3], pos[3]; 385: t->getThrust(thrust); 386: t->getPosition(pos); 387: _body.addForce(pos, thrust); 388: } src/FDM/YASim/RigidBody.cpp 139: void RigidBody::addForce(float* pos, float* force) 140: { 141: addForce(force); 142: 143: // For a force F at position X, the torque about the c.g C is: 144: // torque = F cross (C - X) 145: float v[3], t[3]; 146: Math::sub3(_cg, pos, v); 147: Math::cross3(force, v, t); 148: addTorque(t); 149: } Bertrand. ------------------------------------------------------------------------------ EditLive Enterprise is the world's most technically advanced content authoring tool. Experience the power of Track Changes, Inline Image Editing and ensure content is compliant with Accessibility Checking. http://p.sf.net/sfu/ephox-dev2dev _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel