I love how this video is long, but I want it to be longer lol! This are so helpful to get started with the program. I wish you could have like a long series explaining the nook and cranny of the program. I also want to learn how to read those graphs and data and make sense of it. This video had been really helpful to understand some of the graph, but I want to know how to read them completely.
SUPER helpful, I was looking all over about control surfaces and how to make rudders and ailerons and elevators and this was the only place I could find it. THANK YOU
this is the best vid i have found on vsp aero !!! thankyou.. i am trying to push into the field if dynamic soaring and this appers to be a great tool .. as for the wake simulation lines , being able to see wake vorticies is good in my mind because minimising them with geometry adjusmtnets will lead to a more efficient design
Do you have a tutorial on how to change the 0 on the axes to a darker color in the source code, I don't know how to code and this would be very helpful.
It's okay that they are long. It's interesting. I had no idea you were delving this deep into aerodynamics. The graphical wind tunnel is way cool. Now I know why your maiden flights seem to go so well. 😁
Birds fly pretty darn good without a rudder (h. stab.). V tail seems an easily implementable approximation. Hmmm? edit: Also, interesting vid. on wing design. ruclips.net/video/Hr0I6wBFGpY/видео.html another here. www.newscientist.com/article/mg23631472-600-drone-engineers-accidentally-explain-the-colour-of-albatross-wings/
I wasn't trying to finish a design here, just showing the basics of how the analysis stuff works. Birds can dynamically change their center of mass, wing dihedral, sweep, twist, span, angle of attack, and do this separately for each side, and then all of that for the tail as well, plus the angle between tail and wing too. They're too much of a different construction to really compare to a rigid body plane, although that doesn't stop me from thinking about it fairly often :)
Interesting. However, in your calculation of coefficients, the reference area is set to the default of 100 which is different from your model. This means your magnitudes are higher than the actual.
26:05 why don't you angle the tail so that 0 pitch moment is at the angle of attack where the maximum L/D is? how does OpenVSP handle size of the plane? what are the units for lenght?
Yes, there are plenty of things to tweak if you're making a real design and not a demo video :) When it comes to transferring the design into real-world construction it's usually easier if I can just keep the tailplane and wings 'flat' relative to each other. Pitch moment can be tweaked by CG position too, so I don't fuss over making the untrimmed configuration give me the maximum L/D. Just anywhere along the higher part of the curve is fine, preferably a little off to the left side of the maximum so that pitching nose up will increase L/D slightly. Regarding size/units, I didn't know if VSPAero simulates in that much detail so I did a little check just now. Increasing the size of my plane by a factor of 10 gave a L/D increase of about 20%, so it looks like the scale is actually taken into account. I just consider the units to be centimeters and set the sizes I want accordingly. From there, tweaking to improve the L/D etc at that scale, would automatically improve it at any other scale so the absolute scale doesn't really matter. The real-world L/D measurements are usually nowhere close to the theoretical ones anyway, empirically measured glide ratio is typically about 40% of the value VSPAero shows.
@@iforce2d thanks a lot :) i was doing an efficiency comparison between reflex and a bird tail for flying wings i wish there was something similar to vspaero in fusion360 where i can tell it to sweep any parameter in any range i want and it gives me the best for l/d and graphs for what happens during the sweeps i can dream lol
Ok, I have made a glider. It generates lift, but it flies unstable according to the analysis. I have tried different location for the wing, without any luck. The stabilisator is fairly huge, so I hope it helps. It's wingspan should fit nicely in the trunk of a car. I haven't made any cad files or STL files for laser cut balsa, or a hot wire cutter. If a hot wire cutter is going to be used, I am considering using Jackofoam ( extruded polystyrene foam, used in building construction ). Any tips on fixing the issue? File for OpenVSP: www.dropbox.com/s/iq39j853c6jy9il/myglider.vsp3?dl=0
You have the CG near the trailing edge of the wing, when it needs to be about 25-30% of the wing chord away from the leading edge. Just set the Xref value of the 'moment reference position' to about 4 and it seems ok. In reality to get the CG there might be difficult though, without adding a lot of nose weight - might be better to slide the wing back along the fuselage a bit, or extend the nose longer. You'll also need to angle the elevator (XForm tab, Yrot) at about -5 degrees, so that the neutral-moment angle of attack has positive lift. This is quite a lot of angle, but seems to be necessary because the main wing chord is so large. With that aspect ratio it won't be much of a glider, it's more like a warbird :) I think the stabilizer would be better off at a higher aspect ratio too. I got some decent results with these changes: - CG at 3 - elevator Yrot at -3 - change main wing chord to 10
@@iforce2d I mainly meant for your consideration of static pitch stability. For example, the negative CM vs. alpha slope you reference -- what really matters is the slope dCM/dCL -- which is actually the negative of the static margin. Likewise, the point where the curve crosses zero CM is the trim point -- in CL or alpha. CL will tell you the speed for trim (given density and wing loading). If you generate curves for different elevator deflection, you will see how the trim point moves. Drag is important for performance - but not for static stability. The total drag prediction in VSPAERO is not great. The induced side is OK, the parasite component is weak, and there is no separation drag at all. So, those L/D's will be optimistic. But, from a performance standpoint, we usually look at CL vs. CD -- not CD vs. alpha. Alpha is just a reference angle to a line painted down the side of the airplane. Humans care about it -- airplanes don't. Thanks for putting these videos out there -- I think they will help a lot of users.
@@rmcdo1 I see. I was only looking at alpha in order to match up the results between the alpha vs CMy graph and the alpha vs L/D graph, but now that you mention it I can just graph CMy vs L/D and I only need to look at one graph, would be much simpler.
In my experience that is usually related to the cross section types used. I seem to recall that 'rounded rectangle' is simply not supported and will always crash. I use super-ellipses instead which can be made pretty similar to a rounded rectangle. Circe and regular ellipse are ok too, I would tread carefully with anything else.
@@iforce2d I appreciate the reply! Your videos on VSP have really helped me design these 3d printed wings I've been making. Using what you showed on VSP I've had perfect maiden flights on the last two builds. I've come to the same conclusion regarding the rounded rectangle cross section. I think what I'll do is just design the fuselage and then change the cross section to circle to run VSP aero. Then I'll change it back to rounded rectangle before I export to Fusion.
Try super-ellipse and increase the value of M and N, you can basically get a rounded rectangle, except better because the corners can be rounded separately, and you don't need to keep changing the cross-section to run vspaero etc. www.iforce2d.net/tmp/Selection_658.png
Sorry, I don't know anything about that, other than the basic wing loading shown at 11:59. Like I said at the beginning, everything I know is covered in this video and that's it.
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I love how this video is long, but I want it to be longer lol! This are so helpful to get started with the program. I wish you could have like a long series explaining the nook and cranny of the program. I also want to learn how to read those graphs and data and make sense of it. This video had been really helpful to understand some of the graph, but I want to know how to read them completely.
Ive started using vsp for a college project...the vids are incredibly helpful
This is great my friend, cheers and have a Great weekend.
SUPER helpful, I was looking all over about control surfaces and how to make rudders and ailerons and elevators and this was the only place I could find it. THANK YOU
Always pushing your subs to think, love it
this is the best vid i have found on vsp aero !!! thankyou..
i am trying to push into the field if dynamic soaring and this appers to be a great tool .. as for the wake simulation lines , being able to see wake vorticies is good in my mind because minimising them with geometry adjusmtnets will lead to a more efficient design
Do you have a tutorial on how to change the 0 on the axes to a darker color in the source code, I don't know how to code and this would be very helpful.
It's okay that they are long. It's interesting. I had no idea you were delving this deep into aerodynamics. The graphical wind tunnel is way cool. Now I know why your maiden flights seem to go so well. 😁
I don't know how much call you gotten for it but I'd really like to see how you take this and turn it into an airplane
Same here!
Excellent presentation. Thank you!
Birds fly pretty darn good without a rudder (h. stab.). V tail seems an easily implementable approximation. Hmmm?
edit: Also, interesting vid. on wing design. ruclips.net/video/Hr0I6wBFGpY/видео.html
another here. www.newscientist.com/article/mg23631472-600-drone-engineers-accidentally-explain-the-colour-of-albatross-wings/
I wasn't trying to finish a design here, just showing the basics of how the analysis stuff works.
Birds can dynamically change their center of mass, wing dihedral, sweep, twist, span, angle of attack, and do this separately for each side, and then all of that for the tail as well, plus the angle between tail and wing too. They're too much of a different construction to really compare to a rigid body plane, although that doesn't stop me from thinking about it fairly often :)
Interesting. However, in your calculation of coefficients, the reference area is set to the default of 100 which is different from your model. This means your magnitudes are higher than the actual.
👍👍
very helpful! thank you :)
Great video, thanks
26:05 why don't you angle the tail so that 0 pitch moment is at the angle of attack where the maximum L/D is?
how does OpenVSP handle size of the plane? what are the units for lenght?
Yes, there are plenty of things to tweak if you're making a real design and not a demo video :) When it comes to transferring the design into real-world construction it's usually easier if I can just keep the tailplane and wings 'flat' relative to each other. Pitch moment can be tweaked by CG position too, so I don't fuss over making the untrimmed configuration give me the maximum L/D. Just anywhere along the higher part of the curve is fine, preferably a little off to the left side of the maximum so that pitching nose up will increase L/D slightly.
Regarding size/units, I didn't know if VSPAero simulates in that much detail so I did a little check just now. Increasing the size of my plane by a factor of 10 gave a L/D increase of about 20%, so it looks like the scale is actually taken into account. I just consider the units to be centimeters and set the sizes I want accordingly. From there, tweaking to improve the L/D etc at that scale, would automatically improve it at any other scale so the absolute scale doesn't really matter. The real-world L/D measurements are usually nowhere close to the theoretical ones anyway, empirically measured glide ratio is typically about 40% of the value VSPAero shows.
@@iforce2d thanks a lot :)
i was doing an efficiency comparison between reflex and a bird tail for flying wings
i wish there was something similar to vspaero in fusion360
where i can tell it to sweep any parameter in any range i want and it gives me the best for l/d and graphs for what happens during the sweeps
i can dream lol
I wish it was possible to enter a airspeed range, say 8 to 20 meters/second or 20 to 60 kilometres per hour.
Are you discover, how to launch panel method ?
Ok, I have made a glider.
It generates lift, but it flies unstable according to the analysis. I have tried different location for the wing, without any luck. The stabilisator is fairly huge, so I hope it helps. It's wingspan should fit nicely in the trunk of a car. I haven't made any cad files or STL files for laser cut balsa, or a hot wire cutter. If a hot wire cutter is going to be used, I am considering using Jackofoam ( extruded polystyrene foam, used in building construction ).
Any tips on fixing the issue?
File for OpenVSP:
www.dropbox.com/s/iq39j853c6jy9il/myglider.vsp3?dl=0
You have the CG near the trailing edge of the wing, when it needs to be about 25-30% of the wing chord away from the leading edge. Just set the Xref value of the 'moment reference position' to about 4 and it seems ok. In reality to get the CG there might be difficult though, without adding a lot of nose weight - might be better to slide the wing back along the fuselage a bit, or extend the nose longer.
You'll also need to angle the elevator (XForm tab, Yrot) at about -5 degrees, so that the neutral-moment angle of attack has positive lift. This is quite a lot of angle, but seems to be necessary because the main wing chord is so large. With that aspect ratio it won't be much of a glider, it's more like a warbird :) I think the stabilizer would be better off at a higher aspect ratio too.
I got some decent results with these changes:
- CG at 3
- elevator Yrot at -3
- change main wing chord to 10
What are the units in this program??
Whatever you like. I usually think of them as centimeters.
How do you make the X and Y axis darker like yours??? It would be EXTREMELY helpful if you could share how to do this! Thanks in advance!
16:32 as mentioned in the video, I modified the program and compiled it myself.
github.com/OpenVSP/OpenVSP/compare/main...iforce2d:master
Could you share your version of OpenVSP?
I liked those changes you made in your source code
www.iforce2d.net/tmp/OpenVSP-3.17.1-Linux64.zip
Whether it will run on your system is another question though...
Instead of CMy vs. alpha, you might consider working mainly in terms of CMy vs. CL -- the airplane doesn't really care about alpha.
Surely drag needs to be part of the consideration though?
@@iforce2d I mainly meant for your consideration of static pitch stability. For example, the negative CM vs. alpha slope you reference -- what really matters is the slope dCM/dCL -- which is actually the negative of the static margin. Likewise, the point where the curve crosses zero CM is the trim point -- in CL or alpha. CL will tell you the speed for trim (given density and wing loading). If you generate curves for different elevator deflection, you will see how the trim point moves.
Drag is important for performance - but not for static stability. The total drag prediction in VSPAERO is not great. The induced side is OK, the parasite component is weak, and there is no separation drag at all. So, those L/D's will be optimistic.
But, from a performance standpoint, we usually look at CL vs. CD -- not CD vs. alpha. Alpha is just a reference angle to a line painted down the side of the airplane. Humans care about it -- airplanes don't.
Thanks for putting these videos out there -- I think they will help a lot of users.
@@rmcdo1 I see. I was only looking at alpha in order to match up the results between the alpha vs CMy graph and the alpha vs L/D graph, but now that you mention it I can just graph CMy vs L/D and I only need to look at one graph, would be much simpler.
bascailly alpha v.s Cmy is the lift moment that leads to the stability of the wing right?
Pitching moment, yes.
Thank you for great video.
I really need this info. Now I have a good start. I hope to figure out how to simulate props and share this info with you.
The 'disks' that I talked about at 28:14 are for simulating props
@@iforce2d Yeah, I mean I will try to figure out how to make it to push the plane, not to simulate aerobrake:)
First!
hi, does anyone know if it is possible to find the hinge moment on openvsp?
Whenever I open up VSPaero, the "Launch Solver" button is grayed out and I can't click on it. Any ideas why?
I got it to work, you have to move all the vsp aero executable files to the desktop
vspaero.exe is a separate program, I think it needs to be in the same place as vsp.exe.
I'm having problems running VSPAero simulations with a fuselage. Is there something that will make it work?
In my experience that is usually related to the cross section types used. I seem to recall that 'rounded rectangle' is simply not supported and will always crash. I use super-ellipses instead which can be made pretty similar to a rounded rectangle. Circe and regular ellipse are ok too, I would tread carefully with anything else.
@@iforce2d I appreciate the reply! Your videos on VSP have really helped me design these 3d printed wings I've been making. Using what you showed on VSP I've had perfect maiden flights on the last two builds. I've come to the same conclusion regarding the rounded rectangle cross section. I think what I'll do is just design the fuselage and then change the cross section to circle to run VSP aero. Then I'll change it back to rounded rectangle before I export to Fusion.
Try super-ellipse and increase the value of M and N, you can basically get a rounded rectangle, except better because the corners can be rounded separately, and you don't need to keep changing the cross-section to run vspaero etc. www.iforce2d.net/tmp/Selection_658.png
@@iforce2d Thanks I'll try it.
Please do a video on calculation aerodynamic loads.
Sorry, I don't know anything about that, other than the basic wing loading shown at 11:59. Like I said at the beginning, everything I know is covered in this video and that's it.
@@iforce2d Thank you.
What is that software?
Its called open vsp.. available for free...
Microsoft Word
Lmao....owned.
iforce2d are you stupid or what?
@@javieruriel what
Not long at all! Explained very nicely, been using this program last year to design a drone, and now I am starting to understand it