Flight model issues - aerodynamics.

1st Official Post

    Hi, I am new to Aerofly. I bought it today to help a friend decide on the best sim for flying multicopters.

    Overall, there are many things to like about it, great graphics, a polished interface and it works readily with the Taranis connected via USB.

    To give you a little background, I have been in this hobby for 36 years, a full size flying instructor for 27 years and also professionally reviewed the flight models of numerous PC based flight simulators in the late 90's / 2000.

    I give the quad copter models a thumbs up but the aircraft aerodynamics are lacking as they fail to simulate accelerated stalls.

    The way the aircraft responds during normal flight is fluid and realistic but they do not respond correctly to excessive elevator input as you can basically hold full elevator and continue to fly without stalling and land. This is very unrealistic as most RC aircraft cannot do this.

    As this is a training tool designed to teach newcomers how to fly, I think this oversight is detrimental as the user will not be learning how to avoid stalling during phases like the base turn and final, or aerobatics.

    I am not posting these videos to bash Aerofly but simply to provide constructive feedback to the developers so they can implement better aerodynamics in future upgrades which will improve its value as a training tool.

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    The second video.

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    Hello Rob

    Thanks a lot for making this point. I couldn't have explained it with your words.

    My experience was, in simple words, that Aerofly (and it's predecessors) give you the illusion of being far more capable than you are (and I always switch the options to "most realistic/expert").

    Once you turn to "real life" the shock for "newbies" hits hard. It hit me in a way that I destroyed my first Extra 300 model (1m span)
    I would have never dared to try it, had the sim been more realistic !!

    Thanks a lot
    Mike-DE

    • Official Post

    Hello everyone,

    beeing a free developer for aeroflyRC7, aerofly5 and aeroflyFS aircraft and a glider pilot for about 6 years, I have to correct you there a little bit.
    First of all: The aerofly does simulate stalls with wing drops and also wing rocks ("falling leave") in a full stall.
    Danny and I made a modification of the Katana, "Unlimited" and "Classic", which are part of the stock simulator content.
    That unlimited modification has larger surface deflections, is a lot more tail heavy and it does simulate such
    a large 3D aircraft quite well. We had to compromise a lot but eventually we got the aircraft to do
    knife-edge-spins, flat spins, snap rolls, walls pretty accuratly.
    So please try out the Katana Unlimited and maybe try my modification of the pitts 2b, which is available as a free download here in this forum.

    Most of the aircraft in the Rc7 are too nose heavy to be able to stall.
    Even with full up elevator not every airplane (not even real ones) will stall right away...
    And not every aircraft in the real world will do
    That beeing said... why are most of the aerofly RC7 aircraft set up like that? I don't know.
    But what I'm trying to say is that the aerofly does simulate stalls actually not to bad. Its ok and will get you trained enough to be able to recover from a stall if you choose the right aircrafts.

    We had a similar discussion some years ago. For us the aerofly's stall simulation wasn't accurate enough either. And I would love to see a better stall simulation aswell, especially for the aeroflyFS. Currently the aeroflyFS (1.2) and the aerofly5 simulate stalls without taking the side slip angle to account. The aeroflyRC7 now responds to full rudder and full elevator with a wing drop. So you can actually keep the aircraft in a full stall with rudder only. Some aircaft will do a "falling leave" at that point aswell.
    That's as it should be and like I've experienced it in my dozens of forced stalls in a glider and initiated wing drops.

    But still something isn't quite accurate in the simulation of the stall. I guess its because of an inconsistency in the calculation of the induced drag, which is correctly calculated (when the lift coefficient drops in the stall then the induced drag should reduce aswell) but it just doesn't feel realistic. Thats somewhat the same category as the adverse yaw which is also a bit to large for some aircrafts, like the extra 300 in the aeroflyFS. And there is no parameter for the adverse yaw yet because it does simulate everything correctly!

    Here is how it should look like :D

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    ... my youtube playlist for more videos about aerodynamics: https://www.youtube.com/watch?v=ZOPsQn2Mksg&list=PLTJT1u0RlrTee8ARcmtLwybYv8gpf0L9L&index=19

    Cheers,
    Jan

    Regards,

    Jan

    Rob2160: Rob, thank you for your feedback and your videos regarding aerofly RC 7. We would like to comment on your posting.

    First of all, we have to distinguish here between a model setup (e.g. adjust the various flight parameters ) and the actual flight physics. People tend to mix this up.

    We adjusted most models, such that the stall characteristics are not too pronounced. Most novice and intermediate pilots simply can deal with this a lot better. If we would set up all models to be a lot more sensitive with respect to the stall behaviour we would simply ask too much for most users. So this as an explanation why the models are setup the way they are.

    That being said, it is possible to adjust the models the way you describe, but it does require some real good knowledge on what parameter of the aerofly flight model effects the stall behaviour which can be tricky.

    Thanks for the comments and I understand the logic behind making the aircraft a little "easier" to fly however as Mike mentioned in post #2, this gives the student a false sense of confidence as the real RC aircraft will be far less forgiving (and more costly in a crash)

    Wouldn't it make sense to have an easy selection button for "simple" or "realistic" flight model which gives you the best of both worlds and will allow newcomers to appreciate how much more difficult a real RC aircraft will be.

    Is there a Manual that explains how I could adjust the parameters to try the more accurate stall modelling?

    Regards,

    Rob.

    Edited once, last by IPACS Support (December 2, 2014 at 9:02 AM).

    Hi Jan, thanks for your detailed comments. You are right, if the aircraft are too nose heavy they won't stall if there is insufficient elevator travel.

    I briefly tried the Katana and agree that does have more realistic responses to the stall and I was able to make it do a falling leaf.

    Going back to the Bobcat I used in the video, I can see that the physics model will allow wing drops and even control reversal of the aileron in a stall. I used the following settings.

    CG 0.475
    Airfoilroot
    Attached range - 10
    Stall Range - 12

    Airfoiltip
    Attached range - 6
    Stall range 8

    With these settings I was able to cause the plane to demonstrate strong aileron reversal in a tight turning stall.

    This is very promising as I now know the models can be tuned for better accuracy. I see that the basic set up for most models is too stable and forgiving but can be adjusted for more realism.

    I'll spend a bit of time on some of the models and come back here with settings that I feel cause them to fly more realistically.

    That video of the falling leaf is exactly how the Robin 2160 aircraft does them and it spins beautifully also.

    Thanks again Jan, and also to IPACS support for the comments above.

    As I said earlier, there is a lot to like about this simulator, the graphics are beautiful and I am getting 125 FPS with everything at maximum.

    Edited once, last by IPACS Support (December 2, 2014 at 9:01 AM).

    This is a problem with every simulator I've tried. Aerofly is actually quite a bit better than anything else in this regard.

    The thing with computer simulations is they can't simulate wind well either (again not a knock on aerofly, since imo they are the best at wind too) It's just not real, like at the field. Also the effects of AOA (not during stalls, but just routine flying). In real life when you are flying knife edge for example, the plane or heli will want to lose altitude quickly, especially if you don't have a lot of speed. But in all computer sims I've flown, the aircraft seem to float. Aircraft will just stay airborne forever. At the field, real models are just dying to hit the ground.

    That's my take, in real flying, rc models WANT to crash. When you fly the ground is always beckoning. One false move at low altitude and it's all over. But in sims, this is simply not the case. It's actually hard to crash. I can't really say why this is. It just is. It almost seems like the acceleration of gravity is cut in half in rc sims. All of them are like this. This is especially true with helicopters in sims. And they just can autorotate for years in a sim too. lol

    Of course the biggest problem going from sim to reality is nerves. When flying the sim, you aren't stressing about a mistake, or a failure of some kind, because the model resets in a few seconds. In real life, there could be a lot of money, and certainly a lot of time involved with repairs in the event of an unscheduled landing. So there's no way to model that fear. Especially if it's a several thousand dollar model that you've spent several months building and setting up. So when you're even just a little nervous at the field, your fingers are just a fraction slower, and maybe your reactions are just a little off. I find that tiny amount to have a huge effect on me. After you've flown a model for awhile that goes away of course, but your model has to survive long enough to get you to that point. That's hard on beginners I think. It was on me for sure. I still get very nervous on maiden flights.

    hello,
    a rc simulator allows apprehend the steering and acquire the reflexes.
    Under AeroFly, it's possible to improve the feeling of weightlessness by increasing the weight the model.
    There no effect exists for the stress, yourself must simulate ...