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  #16  
Old 11-30-2017, 05:47 PM
tridge tridge is offline
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Quote:
Originally Posted by flexible2g View Post
This screen shot shows the problem. The motors are not set up for movement in RF.
That is the Cat Tailsitter, which is a non-vectored aircraft. I assumed you were talking about the CUAV_TVBS model (which is what I started this topic to discuss). The CUAV_TVBS is vectored.
The Cat tailsitter is not supposed to tilt its motors. The moveable pod at 90 degrees is needed to make the motors appear with the right orientation, but there is no servo attached.
This is based on a real aircraft, and it flies well. It also flies well in RealFlight. Yaw for this aircraft comes not from tilting the motors, but from the huge elevons.
Note that the "manual" CatTailsitter that I uploaded to the swap pages is a variant of the one that is normally used with ArduPilot control.
Here it is under ArduPilot control in RealFlight8:
https://www.youtube.com/watch?v=yOp-3Uy1DLE
Sorry for the confusion.

Last edited by tridge; 11-30-2017 at 05:47 PM. Reason: fixed typos
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  #17  
Old 11-30-2017, 09:00 PM
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Jeremy Sebens Jeremy Sebens is offline
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Originally Posted by tridge View Post
Jeremy, can you explain a bit about what the Prop Wash Factor does? The docs in the vehicle physics editor help text don't give any hints as to why this would produce a yawing effect like we observe.
The prop wash factor sets the strength of downstream effects of the prop, both axial and helical. In this case, that would include wash effects on the fuselage booms and the fins.

I'd be curious to know if the Caipirinha misbehaves if it's prop wash factor is increased. Prop wash interacts with the fins/rudders, which would be "blown" in the CUAV, but not in the Caipirinha.

Last edited by Jeremy Sebens; 12-01-2017 at 12:13 PM.
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  #18  
Old 12-01-2017, 12:03 AM
tridge tridge is offline
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Originally Posted by Jeremy Sebens View Post
I'd be curious to know if the Caipirinha misbehaves if it's prop wash factor is increased. prop wash interacts with the fins/rudders, which would be "blown" in the CUAV, but not in the Caipirinha.
yes, it happens the same on the Caipirinha. If you set prop wash factor to 50 its fine. If you set it to 60 it gets a noticeable yaw problem.
Does anything different happen in the maths with values above 50?
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  #19  
Old 12-01-2017, 12:10 AM
tridge tridge is offline
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btw, while testing this I also happened to notice that the "NavGuides" current reading is only reading for 1 motor in the Caipirinha. It also doesn't seem consistent with what is sent over the LINK protocol.
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  #20  
Old 12-01-2017, 08:54 PM
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Jeremy Sebens Jeremy Sebens is offline
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Originally Posted by tridge View Post
yes, it happens the same on the Caipirinha. If you set prop wash factor to 50 its fine. If you set it to 60 it gets a noticeable yaw problem.
Does anything different happen in the maths with values above 50?
OK, I'm adding a case to our issue-tracking system.

To my knowledge, there is no discontinuity at 50%. I'll verify as soon as I can.
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  #21  
Old 12-01-2017, 08:58 PM
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Jeremy Sebens Jeremy Sebens is offline
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Quote:
Originally Posted by tridge View Post
btw, while testing this I also happened to notice that the "NavGuides" current reading is only reading for 1 motor in the Caipirinha. It also doesn't seem consistent with what is sent over the LINK protocol.
This is a known issue with our NavGuides. The RPM and energy consumption figures only correspond to one motor. I'll have to look into what value is reported in the FlightAxis Link state vector.
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  #22  
Old 12-01-2017, 09:31 PM
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flexible2g flexible2g is offline
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better

I deleted the rudder. Added symmetrical rudders, at 45%, centered under C/L of motors thrust. Increased power to 140%. Flew ok, but I noticed that when slowly adding for lift off, it moved to the right. You had the props turning backwards, that realty messed up the prop wash big time.
You imported the FBX with the model up side down to spawn, so manual flying is harder at lift off. I am sure, if you would map it completely, and post the TGA here, one of the very good artiest here would create a killer CS for you. Having defferant schemes for top and bottom, is a must for flying.
Note: I don't think there is any gain for the weight of the winglets, I would ditch them, unless you wanted to change them so the model could rest on them, so the rudders would clear the ground before lifoff. If the rudders are not under the motors, you will not get the prop warsh over them for controll.
Attached Files
File Type: rfx CatTailsitter Manual_AV.RFX (48.3 KB, 1 views)
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  #23  
Old 12-01-2017, 11:12 PM
tridge tridge is offline
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Quote:
Originally Posted by flexible2g View Post
I deleted the rudder. Added symmetrical rudders, at 45%, centered under C/L of motors thrust. Increased power to 140%. Flew ok, but I noticed that when slowly adding for lift off, it moved to the right. You had the props turning backwards, that realty messed up the prop wash big time.
Do you realize that the max files and FBX for the model are available for you to modify? I know that isn't the norm on these forums, but for the ArduPilot models we're making them available and you are very welcome to modify them so you can match the graphics to the changes in the physics models.
The files are here:
https://github.com/ArduPilot/SITL_Mo...ailSitters/Cat
The changes you've made result in quite a different aircraft. The orginal design is a model of a real aircraft, and was built so we could test and improve ArduPilot control of that aircraft.
I think the reason you wanted those changes is that RealFlight doesn't have a builtin tailsitter controller. If the multicopter controller in RealFlight could be adapted to support tailsitters then I think you'd find this model very easy to fly without any physics changes.
Cheers, Tridge
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  #24  
Old 12-02-2017, 10:58 AM
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flexible2g flexible2g is offline
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vectored

The key word is vectored! The RF model you posed is not vectored!
Please post a link to a real world model, fully controlled in a 15 mph wind, without any form of vectoring, and no controllable rudder, using only elavon's to control yaw in the wind. Elavon's move air flow the wrong direction, to be good yaw controllers.
I am thinking about how to speed this process.
So lets start in the beginning. For me, when I am getting ready to start a new desighn project, I set some proramiters. Not the least of whitch, is the real world goal! So what is the real world goal of the tailsetter? Why the tailsetter, versis some other desighn?
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  #25  
Old 12-03-2017, 02:20 AM
tridge tridge is offline
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Originally Posted by flexible2g View Post
The key word is vectored! The RF model you posed is not vectored!
Indeed, the Cat is not vectored. Non-vectored tailsitters fly fine. They aren't as agile as vectored, but they are much more common. Please do a google search for dual motor tailsitters, or see the links I gave in the download for the Cat, or lookup the wingtra, which is a commercial aircraft of this type. Thousands of people fly them, and lots and lots of people have done PhDs and masters on how they fly.
Flying them without a flight controller is hard but not impossible. Flying them with a flight controller is easy.
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  #26  
Old 12-03-2017, 10:53 AM
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real world no vectored

Please provide link to real world model, none vectored, none ruddered model, to show that what you wish to do in the worlds best model simulator, which does a very good job of emulating real world aircraft.
Prove me wrong. Take thrust vectoring, giros, and rudder off a model, you DO NOT HAVE YAW CONTROL!
Flaparons,do not controll yaw. Under the best of condishions, whitch is not realistick in the real world. The only thing flaparons can do is twist the air frame untill the wing is vertical, and then you still have no yaw controll for landing.
NO FUN!
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  #27  
Old 12-03-2017, 11:42 AM
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Quote:
Originally Posted by flexible2g View Post
Please provide link to real world model, none vectored, none ruddered model, to show that what you wish to do in the worlds best model simulator, which does a very good job of emulating real world aircraft.
Prove me wrong. Take thrust vectoring, giros, and rudder off a model, you DO NOT HAVE YAW CONTROL!
Flaparons,do not controll yaw. Under the best of condishions, whitch is not realistick in the real world. The only thing flaparons can do is twist the air frame untill the wing is vertical, and then you still have no yaw controll for landing.
NO FUN!
I believe that the model that they are talking about has hardware in the loop connected to realflight with the Flightaxis Link. It is basically a computer controlled RC aircraft. Realflight 8 now allows this type of connection to actual flight hardware to control the sim.

I have a quad that I built with a Pixhawk which runs a version of ardupilot for quads. It is capable of fully autonomous flight without any control inputs. I myself am very green when it comes to this technology myself but it's very interesting to learn about these new capabilities in what can be done with actual RC hardware.

Last edited by csgill75; 12-03-2017 at 11:49 AM.
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  #28  
Old 12-03-2017, 11:54 AM
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This is what I found on one of the models being developed in/for RealFlight

https://pixhawk.org/platforms/vtol/tbs_caipirinha_vtol
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  #29  
Old 12-03-2017, 01:07 PM
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no yaw control

I am all in for what they are trying to accomplish. I can find nothing, like this hovering without vectoring. Elevons can not control yaw.
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  #30  
Old 12-03-2017, 02:52 PM
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Originally Posted by flexible2g View Post
I am all in for what they are trying to accomplish. I can find nothing, like this hovering without vectoring. Elevons can not control yaw.
https://youtu.be/o_95BNzNWnM

In that video is that aircraft I posted about holding a hover with only elevons. It seems to work. It may be using variable thrust as well but I am not sure. The op may have more information on how exactly it works.

It might be worth noting that a human pilot is not in direct control of that aircraft. It's holding its position by GPS lock and is computer controlled. It's probably able to do this because it can react much faster than a human pilot. I harken this to the fly by wire setups in modern fighter jets and commercial aircraft.

Last edited by csgill75; 12-03-2017 at 02:57 PM.
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