Re: [Flightgear-devel] Latest stupid helicopter trick
Maik Justus wrote: Thie is in the fdm (adv. in the bo105.xml file) (with the real angles for the bo) - adv. + resp. Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Latest stupid helicopter trick
Hi Jim Jim Wilson said: The term crab as defined in the webster dictionary is: the angular difference between an aircraft's course and the heading necessary to make that course in the presence of a crosswind. The way I used it refers to the action crab which is flying on that angle (with the nose pointing in a slightly different direction than the one you are traveling). In the case of helicopters it is not only the crosswind effect, but also the anti-torque thrust, correct? I think you are correct. And the vertical stab is not of the original size and the horizontal stab is missing as well as the fuselage. Oh... I hadn't thought about that. How are you maintaining stability on that axis? Very simply: ther is nothing which gives instability on that axis. You mentioned last week that you had ground effect done. Is it worth submitting a patch for that? I am interested to see how it affects take off and landing. Currently it takes almost full collective to break the skids off the ground for take off, and it is almost impossible to get a gentle landing. Of course the landing is probably just my lack of skill, but I suspect the ground effect would do something to assist. I am sorry, but up to now I didn't find the time to test this. I wrote this on my portable in a train, where I had no joystick to test it. Thanks, Jim Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
[Flightgear-devel] shadow
Hi, is it planned to add shadow to the world, at least the shadow of the aircraft? All the best, Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] shadow
Hi, looks good. Maybe someone could add this to the bo105? (Melchior?) Thanks, Maik Curtis L. Olson schrieb: Maik Justus writes: Hi, is it planned to add shadow to the world, at least the shadow of the aircraft? You can actually add a shadow layer to the model directly and keep it at ground level via various model animation directives: http://www.flightgear.org/images/an225-departing-KSFO.jpg It's not a perfect shadow, but it's quick and easy. Curt. -- Curtis Olson HumanFIRST Program FlightGear Project Twin Citiescurt 'at' me.umn.edu curt 'at' flightgear.org Minnesota http://www.flightgear.org/~curt http://www.flightgear.org ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Latest stupid helicopter trick
Hi, the Westland Lynx has nearly the same rotor than the bo (they both were developed in the same project at boelkow). Maik Matthew Law wrote: On 07:50 Thu 27 Nov , Martin Spott wrote: The first is correct, the latter is not (see above). Pilots love this helicopter because of his outstanding manouverability. It's even capable of doing serious aerobatic - up to inverted flying (AFAIR with a modified gear box lubrication), Check out the Westland Lynx. I've seen these at a couple of airshows this year and the pilots did manage quite a bit of inverted flight during their routines. These too have a rigid rotor head with elastomeric bearings and the blades are intentionally made more rigid to prevent tail strikes during high-G and sharp stop maneuvers. Impressive engineering in all modern helos I think you'll agree :-) All the best, Matt. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Latest stupid helicopter trick
Hi, one think/thing added: Maik Justus schrieb: Hi, I try to explain my confusion: Lets think the heli is in forward flying and the rotor is spinning counter clock wise (seen from top, like the bo 105). Relative to air the rotor blades at the left side are slower and on the right side are faster. So they produce more force at the right side and less on the left side. Because of the gyroscopic effect the result is 90° shifted, so the blade will be up in front and down in back (flapping). The heli will rise the nose if you don't correct the cyclic input. (Up to this point I think I understood it.) m is the mass of one pointlike blade r is the radius to this mass (which vary with flapping and teetering) r0 the radius without flapping and teetering w (omega) the rotational speed of the blade a flapping angle The angular momentum ( m r w) is conservated. If the blade flapps up, r will be changed (r=r0 cos a, if we assume the hinge in the rotor center), so w has to be increased (that is what we know as teetering). If we assume a positive cone angle of the rotor (and this is the normal case) than the rotorblade will be faster in front position than in back position. And will produce more force in front position than in back position. And with thy gyro we have a roll moment, but to the right and not to the left as our helicopter has in real. It is very easy to run into more confusion. Lets think of a rotor system like the Jet Ranger has. The rotor can flap free around the center, so the only force to the mast is the centripetal force. The centripetal force is m r w w. Without teetering this force is m r0 w w cos a. If the rotor is tilted to the front and has a positive cone angle the blade will produce higher centripetal force in front position than in back position. A effective force to the rotormast pointing forward results. The CG is lower than the rotor head, so this result in a forward roll moment. ok. But what is the result of the teetering? If m r w is constant, than w must be w0/(cos a) (remember: r=r0*cos a). And the centripetal force is then m r0 w0 w0/(cos a), which means, that a forward tiltet rotor will produce an effective force pointing backward, which is obviously nonsense. In this calculation I forgot to split the centripetal force into a component along the blade (the only direction a force can attac) (which is F *(cos a) ) and at the flapping hinge this force has to be splitted into a component along the mast (the lift) and one perpendicular to it (which makes a rotational moment). the one perpendicular has a (cos a) factor, the parallel one a (sin a) factor. This results: r0 w0 w0 (cos a) for the component perpendicular to the mast and r0 w0 w0 (sin a) parallel to the mast. So teetering has no effect to the forces (in first order). Somehow I lost one (cos a) term in my older calculations which rides me into confusion, but now it seems to be clear to me. But the translational roll moment has still the wrong sign... Does someon know, if the Bell 206 (or the r 22) has this roll moment and how large is it? My only idea to solve this: The teetering hinge at every real heli is not in the rotor center. It is out of center. Every teetering angle produces a force to the blade which wants to reduce the teetering angle, so the change of w will be smaller (the missing angular momentum goes to the rotor mast). But if you look in detail into this, you find, that this is a osscillator, which is nearly in resonance. One solution is to think of a big damping constant, but the teeter hinge at model helicopters needs no damping. Maybe the damping can be explained aerodynamically? I don't know. Or is there a big error in this calculations? Confused, Maik a little bit eased, Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Latest stupid helicopter trick
Hi Andy, Andy Ross wrote: What is the rationale behind the decision to make them rigid on the BO105? The only advantage I can see is that you save a few axles and bearings, which are moving parts that can wear out. But you pay for it in extra stress cycles on the blade, so I can't see how this is a win. The articulation joints really aren't very complicated, especially compared with the cyclic control system which you have to have anyway... Andy It's the flight behavior. This rotor system works in a range from -5 to +5 g (maybe more on the positive side) (i.e. the bell jet ranger rotor works only at positive g ) and has a extremely fast reaction on control input. You can do acrobatics with the bo105 and it is much easier to fly than many other helicopters. Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Latest stupid helicopter trick
Hi David David Megginson wrote: Even as slow as 10 kt, the bo105 barely needs any input from the anti-torque pedals. How realistic is this? It certainly makes flying easy. All the best, David It is very unrealistic. But you can change this very easiely. Just remove the notorque=true tags in the bo105.xml file (or write notorque=false). You should also change the min- and maxcollective of the tail rotor to be unsymmetric (I don't have the original values, I can just guess, maybe -10..+20?) Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Latest stupid helicopter trick
Hello Jim Jim Wilson wrote: One big gap right now is the lack of autorotation. The ground effect needs to be modeled to do that correctly, doesn't it? It's not only the ground effect. The main thing is the power consumption of the rotor, which is up to now very simplified. By the way: I had some time the last days to work on the model. I have changed the calculation of the translational lift and added the ground effect. I have to check this some time and will mail the changes soon. Also the rolling tendency in translational lift is missing. That is a very complicate thing. Allways if I think about I run into confusion. Best, Jim Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: Latest stupid helicopter trick
Hi, Melchior FRANZ wrote: ... and I hope that we'll see Maik again on the list ... with a few patches. ;-) m. Yesterday I found some time (while traveling in a train)... Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Latest stupid helicopter trick
Hi David, David Megginson wrote: Yes, it is a bit more work flying with those changes. Do you mind if I check them in? All the best, David For me it's ok, but remember, that you than need pedals (or another analog controller for this axis) to fly helo. By the way: With this changes the heli is not anylonger parallel to ground (while hovering). It is tiltet to the left to compensate the tail rotor force. Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Latest stupid helicopter trick
Hi Andy, Andy Ross schrieb: Maik Justus wrote: By the way: With this changes the heli is not anylonger parallel to ground (while hovering). It is tiltet to the left to compensate the tail rotor force. That sounds wrong to me. The *rotor* should be tilted, but the airframe is experiencing no net force and should be hanging straight down from the shaft. I might believe, because the side force from the tail acts a little lower than the opposing force from the rotor, that the airframe would experience a small torque away from exactly vertical. But I'd be surprised if this was a large effect -- Yes, this effect is larger if the tail rotor is lower mounted (i.e. Jet Ranger). But as far as I know this effect is stil large for a tail rotor above cg. At the bo the tail rotor is nearly at the same height as the rotor centre. But the forces of the (bo 105) rotor act not in the center of the rotor, but at the position of the (virtual) flapping hinges, which are far outside the center. If you sum they, you find, that they produce a much higher moment to the mast which result in a tilted heli. certainly real helicopters don't appear to be leaning while hovering. :) But you never have looked for this phenomena? Look at a calm day to a hoovering helo and you can see it! Maybe I've misunderstood? Andy Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Latest stupid helicopter trick
Hi, I try to explain my confusion: Lets think the heli is in forward flying and the rotor is spinning counter clock wise (seen from top, like the bo 105). Relative to air the rotor blades at the left side are slower and on the right side are faster. So they produce more force at the right side and less on the left side. Because of the gyroscopic effect the result is 90° shifted, so the blade will be up in front and down in back (flapping). The heli will rise the nose if you don't correct the cyclic input. (Up to this point I think I understood it.) m is the mass of one pointlike blade r is the radius to this mass (which vary with flapping and teetering) r0 the radius without flapping and teetering w (omega) the rotational speed of the blade a flapping angle The angular momentum ( m r w) is conservated. If the blade flapps up, r will be changed (r=r0 cos a, if we assume the hinge in the rotor center), so w has to be increased (that is what we know as teetering). If we assume a positive cone angle of the rotor (and this is the normal case) than the rotorblade will be faster in front position than in back position. And will produce more force in front position than in back position. And with thy gyro we have a roll moment, but to the right and not to the left as our helicopter has in real. It is very easy to run into more confusion. Lets think of a rotor system like the Jet Ranger has. The rotor can flap free around the center, so the only force to the mast is the centripetal force. The centripetal force is m r w w. Without teetering this force is m r0 w w cos a. If the rotor is tilted to the front and has a positive cone angle the blade will produce higher centripetal force in front position than in back position. A effective force to the rotormast pointing forward results. The CG is lower than the rotor head, so this result in a forward roll moment. ok. But what is the result of the teetering? If m r w is constant, than w must be w0/(cos a) (remember: r=r0*cos a). And the centripetal force is then m r0 w0 w0/(cos a), which means, that a forward tiltet rotor will produce an effective force pointing backward, which is obviously nonsense. My only idea to solve this: The teetering hinge at every real heli is not in the rotor center. It is out of center. Every teetering angle produces a force to the blade which wants to reduce the teetering angle, so the change of w will be smaller (the missing angular momentum goes to the rotor mast). But if you look in detail into this, you find, that this is a osscillator, which is nearly in resonance. One solution is to think of a big damping constant, but the teeter hinge at model helicopters needs no damping. Maybe the damping can be explained aerodynamically? I don't know. Or is there a big error in this calculations? Confused, Maik Andy Ross wrote: David Megginson wrote: Maik Justus wrote: Also the rolling tendency in translational lift is missing. That is a very complicate thing. Allways if I think about I run into confusion. Is it just a gyroscopic effect? If I'm not misunderstanding the terminology, this is the rolling moment due to airspeed along the plane of the rotor. One side is moving faster than the other, and produces more force. But like everything with the rotor, it does involve gyro effects. Outside of plain aerodynamic forces, none of the forces or moments on a helicopter act on the rigid body of the airframe. They all cause the rotors to tilt or flap (or even bend, if you really are into modelling this stuff), which *then* causes (and feels) a force/moment on the body. And since the rotor is spinning, it produces all sorts of non-intuitive behavior like the 90° precession phase shift (try to roll it left, it tilts forward, etc...). It's ugly. :) Andy ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: I am new here/ helicopter flight model
Hi Melchior, very good. What do you think about the Long Ranger? Bell build this helo with two different rotor systems (So we would get two new helos in one step). Maik Melchior FRANZ schrieb: On Mon, Oct 13, 2003 at 07:50:50PM +0200, Maik Justus wrote: In the next days I will try to optimize the settings for the bo105 and to write a file similar to the Jet Ranger (not the 3D, just the flight model), I'll start a Jet Ranger 3D model as soon as the bo105 is acceptable. I'm not back at my machine yet, but I'll be early next week. :-) m. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASim helicopter code review
Hi Andy,
I have a problem with my pc, so that I have to send it away for getting
repaired. This is also, why I was not able to answer earlier. (and now I
have to use a mail client without spell check) :-(
I've added remarks in the cited part:
Andy Ross wrote:
OK, I finally had time over the weekend to update my tree, rebuild,
and start investigating the new Helicopter code in YASim. What
follows are the notes that occurred to me on first reading, in roughly
order of importance (most important first). Obviously some of this
criticism may be due to misunderstanding on my part.
Immediately fixable stuff and/or potential bugs
---
Adding a dt parameter to Model::initIteration() looks wrong to me.
This is *initializing* an iteration, not computing one, and shouldn't
be dependent on integration parameters. This method was intended to
compute values that will be static across multiple invocations of the
calcForces() routine during the integration; basically for performance
reasons. You probably want to do your integration work inside the
setState() method instead, using the semi-static _dt stored in the
Model object. The integration timestep won't (can't) change inside of
a single iteration.
I will change this
Wrapping almost the entire body of Airplane::solve() with a giant if()
is, well, bad form; especially, heh, since you didn't indent the
wrapped code to make it clear what was going on :). Wrap the *call*
to the function instead, and/or break it out into solveHelicopter()
and solveAirplane() methods that get selected appropriately. That
function was quite confusing enough as originally written.
I will change this
What exactly is the difference between a Rotorblade and a Rotorpart?
Both of them seem to be analogs of the Surface objects that a Wing is
broken up into. Are they both needed? This is more a documentation
issue than anything else.
I' ve written two different helicopter simulations. One more analytical
(Rotorpart) and one more numerical (Rotorblade). The numerical one is
just for testing the analytical one. You can switch between his two
models by an undocumented switch inside the Rotor statement. Up to now
the numerical model runs often in oszillations and is not working 100%.
I am not sure, if I will delete this form the code in the furture
The difference between Airplane and Helicopter seems to be
implicit, and predicated in code on the existence of a wing and tail
object. I'd rather see this be an explicit relationship, ideally
enforced by the C++ type system but at least by something that reads
clearly and sanely to a human being. That is, if(_isHelicopter)
makes more sense and is easier to maintain than
if((_wing)(_tail)).
Not sure. I.E. the Osprey is a mixture between Airplane and Helicopter.
Some of the new code seems to be cribbed from similar stuff in the
original, which is fine. But it could probably use some
uniquification. Variable names didn't change, so you see loops where
a Rotor variable (originally a Wing) is named w, and gets broken
down into Rotorpart (née Surface) objects named sf. Also, some of
the original comments got pasted into a few places
(Airplane::compileRotor(), for example) where they are clearly
innapropriate.
This will all be changed.
Even better would be finding a way to abstract out the reasons for the
cut-n-paste and merge the two implementations. Most of the
Rotor/Rotor{part|blade} implementation is very similar to the existing
Wing/Surface relationship. Maybe they could share superclasses?
I have to think about this.
Future/Design stuff
---
Adding a new type to the Model() object's getX()/setX() methods every
time a new type of aircraft subpart thingy is invented will get
cumbersome. We should consider using a single object type to
encapsulate the idea of a sub-part at a given position which computes
forces.
Sounds good
Similarly, it would be nice to create a superclass of the Airplane
class (Aircraft, I guess), with subclasses Airplane (including the
solver) and Helicopter (with the rotor stuff). It might get messy,
but this will eliminate most of the existing if(_tail||_wing)
predicates that are peppered around.
Osprey?
I may be wrong, but it seems like the Rotor class is handling its own
engine/throttle/power computations. This should really be unified
with the existing YASim (or even better yet, JSBSim too) engine code,
since all these devices are simply producing torque on a shaft based
on property input. This is complicated by the fact that YASim doesn't
really represent an engine as separate from a propeller right now,
of course. The helicopter code is now (I think) the fourth
architecture for engine modelling in the FlightGear code base. Maybe
now is the time to sit down and come up with a single architecture
into which they can all be plugged. The benefit would be
Re: [Flightgear-devel] Helicopter: First Impressions
Hi Andy, Andy Ross wrote: Since the helicopter mechanism doesn't use the solver, you'll need to fudge a factor that makes sense. The actual number is going to depend in sensitive ways on the size and shape of the aircraft and will probably be impossible to guess in practice (this, after all, was the whole point behind writing the solver in the first place). But you'll probably get into the ballpark by picking coefficients that result from an airplane of a similar size. I am using this code instead the solver: applyDragFactor(Math::pow(15.7/1000, 1/SOLVE_TWEAK)); applyLiftRatio(Math::pow(104, 1/SOLVE_TWEAK)); setupState(0,0, _cruiseState); _model.setState(_cruiseState); _controls.reset(); _model.getBody()-reset(); I took the values from the c172. But maybe the stabs are not working because I use them in different conditions than in an airplane. I use them as a damper with nearly no airspeed, where the local wind is nearly parallel to the surface-normal (or with other words: 90 degree incidence). Maybe you can tell me, if they would produce forces in this circumstances. All the best, Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Helicopter: First Impressions
Hi Jim first: thanks to everyone who helped to put this code into the flightgear codebase. Jim Wilson schrieb: What I have noticed is that overspeed effects don't seem to show up (negative speed on the blades coming back should cause a stall) and if you get it up to far enough over 200 it seems as though it'll hold speed and altitude forever even with the collective all the way down. Best, Jim This is due to the not realistic simulated translational lift. I am searching for a more realistic formula for it. The exact simulation of this is very complicate (and at least I am not able to program this). The helicopter simulation is not finished yet. I will describe later, which functions/ effects are totally missing or simplified. @jim,curt: Maybe you can add also the bell206like.xml, ch47like.xml an as350like.xml to the cvs? I think it is interesting, how different they are. All the best, Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Helicopter: First Impressions
Hello David, I will try to get the oscillations. Maybe I am able to change the bo105.xml to avoid them. Maik David Megginson schrieb: David Luff writes: FWIW, I got sudden yaw oscilations as you describe for no apparent reason as well. I've no idea how to fly a heli though!!! Nor do I, but I'd expect any strange oscillations to happen at very low or very high airspeed, not at a medium cruise speed. I just rebuilt everything from scratch, and it's still happening. Usually, I can stop it with only a tiny change in control position (often pitch), but then it will start again a while later. All the best, David ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] YASim Heli bug ?
Hi, thanks. @curt, jim: Can you fix this in the cvs? On the other hand, this is not critical, because the formula where _c2 is a divisor is already exchanged by a formula where _c2 is a factor (the definition of _c2 has also changed). Thanks, Maik Frederic Bouvier schrieb: Hello, MSVC found the problem below at compile time. Anyway, good work Maik. Cheers, -Fred D:\FlightGear\cvs\FlightGear\src\FDM\YASimcvs diff -u Rotorpart.cpp Index: Rotorpart.cpp === RCS file: /var/cvs/FlightGear-0.9/FlightGear/src/FDM/YASim/Rotorpart.cpp,v retrieving revision 1.1 diff -u -r1.1 Rotorpart.cpp --- Rotorpart.cpp 16 Oct 2003 14:40:13 - 1.1 +++ Rotorpart.cpp 17 Oct 2003 06:29:56 - @@ -347,7 +347,7 @@ float fcw; if(_c2==0) - fcw==0; + fcw=0; else //fcw=vz/_c2*_maxpitchforce*_omega/_omegan; fcw=vz*(_c2-1)*_maxpitchforce*_omega/(_omegan*_omegan*_len*_maxpitch); ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Helicopter: First Impressions
Hi Maik Justus wrote: The helicopter simulation is not finished yet. I will describe later, which functions/ effects are totally missing or simplified. Here it is: Missing: -Downwash -Effect on stabs -Effect on rotor itself -Effect on ground (ground effect) -Engine (The needed power is calculated, but very simplified (i.e. a autorotation is not possible now) , but the rotor now accelerates in 5 sec and hold than the revolution for every circumstances) -Fuel consumption -Garbage collection to the source -Comments in the source Unrealistic: -Translational lift -Teetering (I am not sure, which effect the teetering has. If I try to calculate it, I get some discrepancies) -Lift and drag from the Rotor blades is very simplified. To use realistic values of a realistic airfoil should be not very complicate (and then the needed power would be realistic and autorotation should be possible) -The rotor is simulated at only 4 points. To use many points along the rotor blades is much better. And maybe much more, which I forgot to mention here ;-) The bo105.xml contain only more or less realistic rotors. The fuselage and the stabs are still missing. (the same for bell206like.xml, ch47like.xml and as350like.xml). (I am not sure if the stabs are working correct without the solver. I tried to use fixed values if you specify no wing and hstab, but maybe there is a bug. In the ch47like.xml the vstab seems to have no effect at all) All the best, Maik P.S.: I would be very thankful if someone would correct my english in the README.yasim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: [Flightgear-cvslogs] CVS:
Hi Curtis L. Olson wrote: It also loops quite easily ... not saying that was the first thing I tried. How do you run the collective? How about yaw control? The rudder seemed to act more like an aerodynamic rudder ... not that I know anything about how a helo is supposed to fly ... Curt. The bo really can loop and act quite different to many other helos. (Just try the bell206like.xml, and the heli acts as you supposed (I suppose)) All the best, Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: [Flightgear-cvslogs] CVS: source/src/FDM/YASim Rotor.cpp, NONE,
Hi, Oh, _that_ one is really nice. Although the heli is really very well thanks behaved (even with mouse any keyboard control I find it pretty easy to fly _and_land_)... The bo is a little bit different to most other helicopters. I don't say that this simulation is totally realistic, but it should be really quite similar to the original (as far as I can evaluate that). What still is missing is the aerodynamic of the fuselage and the effect of the downwash to the horizontal stab (which is also missing). Both make it a little bit more difficult. I have builded a file bell206like.xml, use this and see how difficult it is to fly a helicopter. (@curt, jim: could you please add these files to the cvs?) (or change (at the main rotor) relenflaphinge=0.0, delta=.4 weightperblade=55 to get al Jet Ranger like rotor (ok, it has still 4 blades, but its behavior is quite similar to the Jet Ranger)) Or at least remove the 'notorque=true ' statements in the bo105.xml. Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: [Flightgear-cvslogs] CVS:
Hi Innis, Innis Cunningham wrote: Hi Jim While mapping the collective to the throttle would work. It is a bit like mapping a variable pitch prop to a throttle.In most helo's I worked on the throttle was opened wide and then the collective was pulled on. On most modern helos the engine is controlled fully automatically, so that you control only the pitch. But in some future I (or someone else?) will add realistic engine simulation to the rotor, than you can control it by hand... It is very interesting to see the look on the passengers faces when the pilot has not applied full power and the helo gets out of ground effect.As the rotor starts to take the full weight of the A/C the rotor speed drops and the helo settles gently back to earth. As the helo has no control surfaces the direction has to be determined by differential lift on the main rotor blades. To go forward the rear going rotor blade has to provide more lift then the forward going rotor blade.And to go left the right going blade supplies more lift then the left going blade.So to work the Cyclic would require a cross calculation of the position of the aileron prop and the elevator prop at any given time. It is simulated exactly like this. The tail rotor could be tied to the rudder but it should give equal rotation around its axis regardless of the forward speed or lack of it of the helo. Hm. I hink this is only correct for acrobatic (3D) model-helos with a (so called) heading lock gyro, but not for real helicopters (maybe the eurocopter tiger acts like this, not sure) (correct me, if I am wrong). Hope this helps and makes sence Cheers Innis The mad Aussi All the best, Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: I am new here/ helicopter flight model
Hi, now I understand my problem. 1.) the rotations specified in the bo105.xml are done bottom to top (not a big problem, but surprising) 2.) if you rotate more than one object in rotation, than these objects seem to be grouped, so that if you want to rotate a single object of this group in another rotation all objects are rotated. I wanted to do the rotation for the incidence first and then the one for the flapping angle, both for every blade separately. In a last step I wanted to rotate the head and the 4 blades with one single rotation around the rotor mast. This last rotation is now separated in 5 single rotations and everything works :-) Maik Melchior FRANZ schrieb: On Tue, Oct 07, 2003 at 07:21:45PM +0200, Erik Hofman wrote: Since Melchior is away for some time [...] Yeah. Military exercises out in the woods ... I'll be back ... in about a week. :-) I did look at the animation file and it looks like he didn't add animation for separate blades yet. Yes, rotor is just the rotor head, and each blade is a separate object. I thought about animating the blade twist, but this can be changed at any time. Just don't tweak the ac model too much, because the master file is in Blender format! Animation of the whole rotor disc can and will be done. I'd also like to have the blades bended down if they stand still and building a disc at higher rotational speeds, similar to the Wright Flyer wings. But I need glass and at least rudimentary interior first, so that the Bo isn't transparent from inside. m. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: I am new here/ helicopter flight model
Hello, I've mailed the source and the files needed for using this with Melchiors Bo105 to Erik, Curt, David and Jim. It should be easily included to the actual source files. It is fully compatible to the old yasim. The simulation parameters are not optimized, but the flight behavior should be similar to the real one. In the next days I will try to optimize the settings for the bo105 and to write a file similar to the Jet Ranger (not the 3D, just the flight model), and a file for a chinook like helicopter (both not optimized (missing data), just to demonstrate how to). And I will start to clean the code, and to comment it. The flight model is not finished yet, but works quite nice. All the best Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: I am new here/ helicopter flight model
Hello Erik, I tried to add animation for separate blades, but I failed. (The animation file seemed to me that it is possible, but...). The helicopter model is working, but I am still debugging. I use two different approaches, one more analytical and one more numerical, and my aim is, that both result in (nearly) the same flight behavior. Up to now, they differ in some details, more than I can understand. And I don't know which approach is wrong, maybe both. And some garbage collection on the source and some documentation is missing... Some other details are missing, but they are not necessary for the first version. Maik Erik Hofman schrieb: Maik Justus wrote: Hi Melchior, meanwhile I am using your bo to fly with fg, but I have a problem. My flight model puts out the flapping angle and the incidence angle for every blade, so I wanted to animate the 4 blades separately. But if i rotate a blade separately (blatt1 blatt4), I see no rotating in the 3D view. If I rotate rotor, the complete rotor (incl. blades) is rotated. I supposed the blatt1...blatt4 to be the blades and rotor to be the rotor head, but it seems, that rotor is the complete rotor; but what are blatt1...blatt4? Maik, Since Melchior is away for some time, but he sent me the model of the Bölkow to include in the base package in case you got the helicopter model ready before he gets back. I did look at the animation file and it looks like he didn't add animation for separate blades yet. In case you are creating your own modifications to the animation file, you have to animate every blade by itself because they don't share a single rotation axis ... Erik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: I am new here/ helicopter flight model
Hi Carsten, oh, I am not so good in writing lines, which explain how to fly a heli. And in detail, I only know how to fly a model helicopter. But you can find a very detailed explanation written by a real helicopter pilot at http://www.cybercom.net/~copters/ Maik [EMAIL PROTECTED] schrieb: Hi Maik, I know it's a little early for my question, but I am writing a FG Flying Tutorial and want to add a chapter about heli flying. Would you mind sending me a couple of lines describing how to handle a heli? The only information I got, is the FLY II manual and I do not know, how good it is. TIA, Carsten Maik Justus schrieb: Hello Erik, I tried to add animation for separate blades, but I failed. (The animation file seemed to me that it is possible, but...). The helicopter model is working, but I am still debugging. I use two different approaches, one more analytical and one more numerical, and my aim is, that both result in (nearly) the same flight behavior. Up to now, they differ in some details, more than I can understand. And I don't know which approach is wrong, maybe both. And some garbage collection on the source and some documentation is missing... Some other details are missing, but they are not necessary for the first version. Maik Erik Hofman schrieb: Maik Justus wrote: Hi Melchior, meanwhile I am using your bo to fly with fg, but I have a problem. My flight model puts out the flapping angle and the incidence angle for every blade, so I wanted to animate the 4 blades separately. But if i rotate a blade separately (blatt1 blatt4), I see no rotating in the 3D view. If I rotate rotor, the complete rotor (incl. blades) is rotated. I supposed the blatt1...blatt4 to be the blades and rotor to be the rotor head, but it seems, that rotor is the complete rotor; but what are blatt1...blatt4? Maik, Since Melchior is away for some time, but he sent me the model of the Bölkow to include in the base package in case you got the helicopter model ready before he gets back. I did look at the animation file and it looks like he didn't add animation for separate blades yet. In case you are creating your own modifications to the animation file, you have to animate every blade by itself because they don't share a single rotation axis ... Erik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: I am new here/ helicopter flight model
Hi Melchior, meanwhile I am using your bo to fly with fg, but I have a problem. My flight model puts out the flapping angle and the incidence angle for every blade, so I wanted to animate the 4 blades separately. But if i rotate a blade separately (blatt1 blatt4), I see no rotating in the 3D view. If I rotate rotor, the complete rotor (incl. blades) is rotated. I supposed the blatt1...blatt4 to be the blades and rotor to be the rotor head, but it seems, that rotor is the complete rotor; but what are blatt1...blatt4? Maik P.S.: is there a switch, to put on shadow of the Aircraft on the ground? Melchior FRANZ wrote: * Melchior FRANZ -- Wednesday 01 October 2003 16:34: I start with a BO105. But as this will be my first (non-building) 3D model, I guarantee for nothing. And I'll be away the next two weeks, so if someone impatiently starts his own attempt, I won't be sad. :-) No, wait. I =will= be sad ... because I've already done the difficult parts in Blender): http://www.unet.univie.ac.at/~a8603365/bo105.jpeg (20kB) I've hacked a fgfs package together that you can unpack in the Aircraft directory. It allows to fly the helicopter with a modified j3cub 'aero': fgfs --aircraft=bo105 http://www.unet.univie.ac.at/~a8603365/bo105.tar.gz (27kB) There's still a lot to do: many details, glass windows, interior, texture, better animation, ... as it is now, you can see the landscape through the window holes. :-/ m. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: I am new here/ helicopter flight model
Hi Franz, very nice! I will use this to test my flight model. Maik Melchior FRANZ wrote: * Melchior FRANZ -- Wednesday 01 October 2003 16:34: I start with a BO105. But as this will be my first (non-building) 3D model, I guarantee for nothing. And I'll be away the next two weeks, so if someone impatiently starts his own attempt, I won't be sad. :-) No, wait. I =will= be sad ... because I've already done the difficult parts in Blender): http://www.unet.univie.ac.at/~a8603365/bo105.jpeg (20kB) I've hacked a fgfs package together that you can unpack in the Aircraft directory. It allows to fly the helicopter with a modified j3cub 'aero': fgfs --aircraft=bo105 http://www.unet.univie.ac.at/~a8603365/bo105.tar.gz (27kB) There's still a lot to do: many details, glass windows, interior, texture, better animation, ... as it is now, you can see the landscape through the window holes. :-/ m. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] I am new here/ helicopter flight model
David Megginson writes: Maik Justus writes: ... The changes are based on the 0.9.2 Version (I hope, that there are not so many differences to the development Version). In that case, we're probably better off with your diffs against 0.9.2 than with the full files. I have only changed/added files in the yasim directory. Meanwhile I have checked the cvs for changes in this directory and there were only minor differences, which I have added to my files. Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] I am new here/ helicopter flight model
Hi Jim, Jim Wilson writes: Maik Justus [EMAIL PROTECTED] said: So there is still some work, but if someone want to have this (alpha-)source just let me know where to mail it (but let me first search for bugs a few days...). The changes are based on the 0.9.2 Version (I hope, that there are not so many differences to the development Version). What I could need is a helicopter (the 3D-Model), the c172 looks a little bit strange when flying like an helicopter. It would be helpful, if the angle of the Rotor blades (to the mast) would be visible. The flight model puts out this angle for 4 positions (front, right, back, left). Maik Very cool! If you want to send the source, I'll try and figure out if it can be merged with the current cvs. Probably it can fairly easily. I will mail the code soon. Will you be available to do further work on the model depending on feedback? At least in the next future, yes. Best, Jim Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
[Flightgear-devel] I am new here/ helicopter flight model
Hello, I am new here in this mailing list and want to introduce myself. My name is Maik Justus, I am living in Bielefeld (Germany) and one of my hobbys is rc-model flying, especially helicopters. I am an physicist and have now some time after Ph.D. and before first job... About 10 years ago I've programmed most parts of Das Hexagon Kartell, a helicopter flight simulator, but only sold in Germany. (I did the flight model, most parts of the graphics engine, video compression, 3D tools, etc.) In normal flying it is quite realistic, but you can drive it into strange behavior. I developed the flight model on a 386 completely with integers to speed up the code. To get faster code some simplifications of the physic and mathematics were necessary, which results in the partly unrealistic behavior. It only can simulate jointless rotors (as on the Bo105, BK117), but with some cheats other rotors systems worked not so bad. A short time ago I found flightgear in the net, but without helicopter flight model. I looked in the code, if it is complicate to put in a heli flight model for myself. I decided to extend the yasim flight model. I added a rotor statement, so that you can add one or more rotor(s). The wing and hstab are now optional (if they are missing the solver is not invoked and fixed values (from the 172) are taken. I added a mstab statement, for mirrored stab, so exactly the same as wing but not effected by the solver. It should be possible to simulate every helicopter with fixed rotor mast (sorry to the ospray (or is it named osprey?) fans). The model feels quite realistic, but I can not really judge or optimize the settings because I am only a rc-model helicopter pilot. Some simplifications are made in the model, but I hope that they have no effect to the realism. I have some detailed information's about the BO105, so I tried to simulate its rotor head. Simultaneously I try a Bell206 like rotor (which is much harder to fly with), but I have not enough data for this helicopter now. Some details are still missing (i.e. rho of the air is ignored, and the rotor is not producing any torque), but this will be added soon (the torque will be switch able). Also missing is the engine, the rotor-RPMs are fixed up to now. Probably there are some bugs, maybe a sign somewhere or a knot in my brain developing the formulas (the mix between metric and English units was also not very helpful). By the way, the documentation is mostly drawn on paper... So there is still some work, but if someone want to have this (alpha-)source just let me know where to mail it (but let me first search for bugs a few days...). The changes are based on the 0.9.2 Version (I hope, that there are not so many differences to the development Version). What I could need is a helicopter (the 3D-Model), the c172 looks a little bit strange when flying like an helicopter. It would be helpful, if the angle of the Rotor blades (to the mast) would be visible. The flight model puts out this angle for 4 positions (front, right, back, left). Maik ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
