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antigoon78
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Oct 27 2013, 5:46 PM (365 w, 1 d)

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May 10 2016

antigoon78 added a comment to T74047: Blackfoot helicopter roll axis placement.

I'm afraid the vids don't convince me. I actually see exactly my point, although it seems to pivot around a lower point, at the moment that the rotor is tilted the lifting force also provides horizontal motion, so it seems to move around a lower point. Again, as much as it is applicable to my perception it is to yours. Your quote: 'Human perception and intuition, on the other hand, are faulty,' And what you see in a video is the same as I do, but with different interpretation. At this moment wel could both be right or wrong.

Just as a reminder, a helicopter is actually suspended instead of lifted. All forces that induce motion originate at the point of suspension. So I say it's still not just CoG / CoM. Look at this little picture.

http://www.cfidarren.com/hlesson5.htm

May 10 2016, 6:57 AM · Arma 3
antigoon78 added a comment to T74047: Blackfoot helicopter roll axis placement.

By the way, this phenomenon is not as irritating in other models, mainly in the Blackfoot/Comanche.

May 10 2016, 6:57 AM · Arma 3
antigoon78 added a comment to T74047: Blackfoot helicopter roll axis placement.

I've looked around, couldn't find my books on helicopters. I also, like Fri13 seemed to remember that there is that play between CoG, CoM and the place where all driving forces originate (being the rotor head). I just wish i had the books to prove my memory right.

May 10 2016, 6:57 AM · Arma 3
antigoon78 added a comment to T74047: Blackfoot helicopter roll axis placement.

True, but nog JUST CoG, that's my only point here. And my original observation about the axis placement still persists. I don't want to make this an elaboration about physics, I just want an acceptable flight model. Not perfect, it's not a flight sim, just somewhat more believable.

May 10 2016, 6:57 AM · Arma 3
antigoon78 added a comment to T74047: Blackfoot helicopter roll axis placement.

Right. So i will adjust that. By the way ( I had to do some digging in my head, i once was educated for 4 years as an aircraft maintenance engineer and helo's were extensively taught) there is actually a play between the center of force (ie the rotor head/swash plate) and the CoG. So it's actually not JUST CoG. Helo's are a strange beast of dynamics. But i'd have to try and find my helicopter books to really see what that exactly was.

May 10 2016, 6:57 AM · Arma 3
antigoon78 added a comment to T74047: Blackfoot helicopter roll axis placement.

You are absolutely correct about that CoG comment. The only thing is that (wiki quote:) For helicopters in hover, the center of mass is always directly below the rotorhead. In forward flight, the center of mass will move aft to balance the negative pitch torque produced by applying cyclic control to propel the helicopter forward; consequently a cruising helicopter flies "nose-down" in level flight. (end quote)

But still, in the blackfoot the roll axis is not placed somewhere in the middle of the aircraft where it should be, but on the bottom of its fuselage. I play massive amounts of FSX and have played some DCS, and the way these helicopters turn is completely different to the blackfoot. I've read most of the comments you've posted in the other thread, and i cant argue with you reasoning. But that doesn't mean that the roll axis on the Blackfoot is correctly placed.

May 10 2016, 6:57 AM · Arma 3
antigoon78 edited Steps To Reproduce on T74047: Blackfoot helicopter roll axis placement.
May 10 2016, 6:57 AM · Arma 3