CARBON FIBER DISCUSSION

[Zoom Master]

Okay 👍. I realized that it doesn’t work well if free too….

Yeah....

 

[Zoom Master]

Yeah it wont even let me view any simulations now which is crazy. There is a limit of one simulations per week......

 

[telnar1236]

Pretty good for now im learning about airfoils and drag and stuff like that but I have also learnt that almost any software that does anything remotely useful is paid and isn't free so yeah.......

Before kicking off any simulations, it's important to understand aerodynamics at least decently and have a good sense of how everything should behave so that you know if your simulation is giving plausible results. Most of the time I'd advise against using simulations as a tool for rc planes at all unless you want to do them for their own sake, but designing a 300+ mph plane is a situation where simulations are an appropriate tool. That said, if you don't know how to set up the model, you'll get nonsense results - as the saying goes, garbage in, garbage out.

For more basic analysis, xflr5 is great and it's free. You need some understanding of aerodynamic principles to use it, but it's fairly user friendly as far as CFD goes. XFoil and AVL (Athena Vortex Lattice) are also free and have lower system requirements, but are substantially more difficult to use and don't offer all that much more than xflr5 unless you're getting into the weeds of airfoil design or control theory. Probably more difficult than using the software is knowing what the results mean. Below is a picture of results from an xflr5 simulation.

For more complicated simulations, Simflow has a free version which allows meshes up to 200,000 nodes. You're not going to get perfect results, but it's still very capable and significantly more than what you need for RC purposes. It is a couple of orders of magnitude more difficult than xflr5 and you need to have a pretty strong understanding of aerodynamics and some basic knowledge of CFD in order to get anything resembling an accurate result out of it. You also need some decent processing power and memory. That said, it's also hugely more capable and powerful than xflr5. Below is an example of some simulation results from Simflow using Paraview to process them showing a wing apex flap creating a vortex on an F-106 I designed. Simflow doesn't output data as nicely and neatly as xflr5 so a lot of the time you need to create your own graphs in google docs or excel too, although you can get Paraview to do it.

 

[Zoom Master]

Before kicking off any simulations, it's important to understand aerodynamics at least decently and have a good sense of how everything should behave so that you know if your simulation is giving plausible results. Most of the time I'd advise against using simulations as a tool for rc planes at all unless you want to do them for their own sake, but designing a 300+ mph plane is a situation where simulations are an appropriate tool. That said, if you don't know how to set up the model, you'll get nonsense results - as the saying goes, garbage in, garbage out.

For more basic analysis, xflr5 is great and it's free. You need some understanding of aerodynamic principles to use it, but it's fairly user friendly as far as CFD goes. XFoil and AVL (Athena Vortex Lattice) are also free and have lower system requirements, but are substantially more difficult to use and don't offer all that much more than xflr5 unless you're getting into the weeds of airfoil design or control theory. Probably more difficult than using the software is knowing what the results mean. Below is a picture of results from an xflr5 simulation.
View attachment 252127
View attachment 252128
For more complicated simulations, Simflow has a free version which allows meshes up to 200,000 nodes. You're not going to get perfect results, but it's still very capable and significantly more than what you need for RC purposes. It is a couple of orders of magnitude more difficult than xflr5 and you need to have a pretty strong understanding of aerodynamics and some basic knowledge of CFD in order to get anything resembling an accurate result out of it. You also need some decent processing power and memory. That said, it's also hugely more capable and powerful than xflr5. Below is an example of some simulation results from Simflow using Paraview to process them showing a wing apex flap creating a vortex on an F-106 I designed. Simflow doesn't output data as nicely and neatly as xflr5 so a lot of the time you need to create your own graphs in google docs or excel too, although you can get Paraview to do it.
View attachment 252129

U are 100% correct it is sort of useless to do any time of simulations if u have zero understanding of aerodynamics. I am slowly learning about drag, air pressure and aerodynamics.......I'll go and try out some of those simulation softwares.....but u are right about not needing simulations for rc planes but when ur designing a plane that is going 300 mph plus I would beg to differ.

 

[Piotrsko]

Free: you do get what you paid for. Don't forget TANSTAAFL, motto of the moon colony per Asimov

Before computers, one could design such an aircraft, many did. Was iterative more expensive and time comsuming. It wasnt until ten years ago Benjamin Delmar discovered the high speed stall aspects of the Granville Brothers series in turns. Safe doing that at 5,000 ft sucks when on the deck.

 

[Zoom Master]

Free: you do get what you paid for. Don't forget TANSTAAFL, motto of the moon colony per Asimov

Before computers, one could design such an aircraft, many did. Was iterative more expensive and time comsuming. It wasnt until ten years ago Benjamin Delmar discovered the high speed stall aspects of the Granville Brothers series in turns. Safe doing that at 5,000 ft sucks when on the deck.

The Granville Brothers series ? Never heard of that....and thankfully it is way easier for one to design high speed airplanes than it was say 10 years ago or even 20 years ago nowadays anybody with a computer can design an aircraft...I myself am a prime example of this....

 

[Zoom Master]

And to be perfectly honest im not doing any testing right now im way to inexperienced and do now have enough knowledge to even know what all those graphs mean...I have been doing research recently learning what drag is, what air pressure is and how it will affect my plane.

 

[Zoom Master]

And that carbon airplane im planning on building ? Yeah im building one out of foamboard first then out of carbon as I wanna see what issues there are with the airframe and what speeds I can reach with foambaord !

 

[Zoom Master]

Also saw someone using water to cool their electronics on a drone that goes 340 mph that is pretty smart according to the guy who made the drone he used water cooling because using air would augment the drag of the whole drone...would it be a smart for me to cool my electronics with water as well or should I just stick to using air ?

 

[Mr NCT]

The Granville Brothers series ?

Granville Brothers Aircraft - Wikipedia

en.wikipedia.org

 

[Zoom Master]

Granville Brothers Aircraft - Wikipedia

en.wikipedia.org

Ohh ok makes sense.

 

[Piotrsko]

Not on for a couple of hours because I need to eat and sleep, miss.a.lot. yuppa the GB series. They believed if it wasn't increasing flight speed, it shouldn't be on the plane, sometimes to the failure of the plane. Hardcore.

 

[Zoom Master]

Not on for a couple of hours because I need to eat and sleep, miss.a.lot. yuppa the GB series. They believed if it wasn't increasing flight speed, it shouldn't be on the plane, sometimes to the failure of the plane. Hardcore.

Well that is crazy but hey there were able to reach 300 mph which was the fastest airplane of its time (in 1932)

 

[Zoom Master]

Not on for a couple of hours because I need to eat and sleep, miss.a.lot. yuppa the GB series. They believed if it wasn't increasing flight speed, it shouldn't be on the plane, sometimes to the failure of the plane. Hardcore.

And btw whats a good place to start learning about aerodynamics and airplane design ?

 

[Zoom Master]

And btw whats a good place to start learning about aerodynamics and airplane design ?

I've got the basics down from watching different YouTube videos and reading some books.

 

[telnar1236]

And btw whats a good place to start learning about aerodynamics and airplane design ?

Depends on what your end goal is. If you want to develop an intuitive understanding of how everything fits together, building a few foam board planes is a good idea. You'll quickly get more of a sense of what does and doesn't work. In the world of rc planes, this is how a lot of good designers seem to work - by rules of thumb and experience and even if you know the science well, it's not really a substitute for experience.

If you just want to run simulations, watching a bunch of tutorials on the software you're using is your best bet. Especially with XFLR5, the documentation and tutorials are quite good and do a good job explaining what everything means from a fairly basic level. Here are some good one for XFLR5.

xflr5 tutorial

My first attempt at a video tutorial for xflr5. Feel free to leave your comments, I'll try to improve these videos based on your feedback The project file us...

www.youtube.com

If you want a good understanding of the science behind a lot of it, unfortunately you need a ton of math - most of fluid dynamics operates in the realm of calculus and differential equations, many of which do not have closed form solutions and must be solved numerically, hence the common use of simulation software.

In order to design a working plane, you absolutely do not need to know the math though. The rules of thumb and a sense of what goes where are much more important to develop first as well as a commonsense idea of what your answers should roughly be and what will contribute to them. You can never capture every factor contributing to the loads in your models or calculations so the most important thing to know is what will contribute significantly and what you can ignore a lot of the time.

 

[Zoom Master]

Depends on what your end goal is. If you want to develop an intuitive understanding of how everything fits together, building a few foam board planes is a good idea. You'll quickly get more of a sense of what does and doesn't work. In the world of rc planes, this is how a lot of good designers seem to work - by rules of thumb and experience and even if you know the science well, it's not really a substitute for experience.

If you just want to run simulations, watching a bunch of tutorials on the software you're using is your best bet. Especially with XFLR5, the documentation and tutorials are quite good and do a good job explaining what everything means from a fairly basic level. Here are some good one for XFLR5.

xflr5 tutorial

My first attempt at a video tutorial for xflr5. Feel free to leave your comments, I'll try to improve these videos based on your feedback The project file us...

www.youtube.com

If you want a good understanding of the science behind a lot of it, unfortunately you need a ton of math - most of fluid dynamics operates in the realm of calculus and differential equations, many of which do not have closed form solutions and must be solved numerically, hence the common use of simulation software.

In order to design a working plane, you absolutely do not need to know the math though. The rules of thumb and a sense of what goes where are much more important to develop first as well as a commonsense idea of what your answers should roughly be and what will contribute to them. You can never capture every factor contributing to the loads in your models or calculations so the most important thing to know is what will contribute significantly and what you can ignore a lot of the time.

I want to understand what makes an RC plane fly and what factors make an RC plane—or anything in general—go faster. And also what is drag ? And how it affects a planes ability to go faster - stuff like that. I dont want to learn all the science behind it, as im aware that there is gonna be a lot of maths involved so for now thats all I wanna learn. Which now that I think about it shouldn't be to difficult.

 

[telnar1236]

This is a good source from NASA.

Beginners Guide to Aeronautics | Glenn Research Center | NASA

Do you ever wonder how airplanes fly? How does a pilot control the movement of the airplane? How did the Wright Brothers invent the airplane? Why are the

www1.grc.nasa.gov

And this is a good place to start - it summarizes the balance of forces on a plane and what each one does.

Four Forces on an Airplane | Glenn Research Center | NASA

A force may be thought of as a push or pull in a specific direction. A force is a vector quantity so a force has both a magnitude and a direction.

www1.grc.nasa.gov

Unfortunately, there is a pretty steep jump between basic concepts and simple scaling rules like Drag = dynamic pressure * reference area * coefficient of drag and anything that will allow you to predict the performance of a new design. In a very real sense, the vast majority of aerodynamics is the math. This is NASA's intro to aerodynamic forces from the same website.

Aerodynamic Forces | Glenn Research Center | NASA

When two solid objects interact in a mechanical process, forces are transmitted, or applied, at the point of contact. But when a solid object interacts

www1.grc.nasa.gov

Your best bet without wanting to deal with math (or even if you decide to do a ton of it) is to experiment and slowly increase the speed of the planes you build until you're hitting your target. It will be very difficult to go from not having designed much to hitting 100 mph much less 300 mph.

To be clear, I'm not trying to discourage you from a 300 mph plane - it's a cool project and would be interesting to see. I'm just suggesting that it's a big challenge and it will be necessary to take it in steps in order to gain the practical knowledge and experience to build such an insane plane.

 

[Zoom Master]

This is a good source from NASA.

Beginners Guide to Aeronautics | Glenn Research Center | NASA

Do you ever wonder how airplanes fly? How does a pilot control the movement of the airplane? How did the Wright Brothers invent the airplane? Why are the

www1.grc.nasa.gov

And this is a good place to start - it summarizes the balance of forces on a plane and what each one does.

Four Forces on an Airplane | Glenn Research Center | NASA

A force may be thought of as a push or pull in a specific direction. A force is a vector quantity so a force has both a magnitude and a direction.

www1.grc.nasa.gov

Unfortunately, there is a pretty steep jump between basic concepts and simple scaling rules like Drag = dynamic pressure * reference area * coefficient of drag and anything that will allow you to predict the performance of a new design. In a very real sense, the vast majority of aerodynamics is the math. This is NASA's intro to aerodynamic forces from the same website.

Aerodynamic Forces | Glenn Research Center | NASA

When two solid objects interact in a mechanical process, forces are transmitted, or applied, at the point of contact. But when a solid object interacts

www1.grc.nasa.gov

Your best bet without wanting to deal with math (or even if you decide to do a ton of it) is to experiment and slowly increase the speed of the planes you build until you're hitting your target. It will be very difficult to go from not having designed much to hitting 100 mph much less 300 mph.

To be clear, I'm not trying to discourage you from a 300 mph plane - it's a cool project and would be interesting to see. I'm just suggesting that it's a big challenge and it will be necessary to take it in steps in order to gain the practical knowledge and experience to build such an insane plane.

Well to be honest I have no issue doing maths to predict the performance of an aircraft and im willing to do a lot of it if needed. And I have already broken 100 mph it isn't that hard to do almost any plane with a powerful enough motor can reach 100 mph. My first major milestone is 200 mph and then I will level it up to 300 mph.

 

[L Edge]

Well to be honest I have no issue doing maths to predict the performance of an aircraft and im willing to do a lot of it if needed. And I have already broken 100 mph it isn't that hard to do almost any plane with a powerful enough motor can reach 100 mph. My first major milestone is 200 mph and then I will level it up to 300 mph.

Could you talk about your flying background and explain how you are going to train yourself to be ready to do 200mph and the goal of 300mph?