MachUp5 Units, aerofoil selections and ultimate loads.

[freezatron]

Hi Team MachUp,

I've had a quick play with MachUp 5 and it's not clear to me what the model making units are and I can't find a way of selecting them.

There seems to be a lot of variation of units used across the program, would be nice if one could set everything to metric or imperial with one button, I am new to this tool so perhaps I have missed something obvious, apologies if so :)  

Also regarding aerofoil selection in the model making section it says "for visual purposes only" or something to that effect,  does that mean I need to manual input the various coefficients for a given Reynolds number at each iteration of angle of attack ? 

Lastly, can MachUp be used to calculate the loads on the control surfaces ?

If it helps the project I am working on is a foot launched man carrying aerobatic glider and it is my hope this tool might help me get in the right ball park for the aerodynamics and component loads so I have a reasonable enough basis to start my structural calculations and the iterations there in with the aim of building and flying it.

Naturally I will be testing the design with quarter scale RC models first.

But before I build anything I would like to play around with the idea and fill in the gaps in my knowledge, I'm a pilot with a dream, can you tell ? :)  

Cheers.

Paul.

[Cory]

Hi Paul

Under the "Condition" tab, you can select the units. I believe this also sets the units for your geometry.

Yes, you are correct about manually inputting your airfoil coefficients for each Reynolds number. You shouldn't need to do that at each angle of attack though. I highly recommend that you switch to using MachUpX if you are planning to do Reynolds-dependent analysis and large alpha/Reynolds sweeps. MachUpX can be scripted in Python which means you can automate the whole process. MachUpX can also accept nonlinear databases of airfoil coefficients, rather than just a simple linear model. If you're not familiar with Python, it's really easy to pick up and well worth the effort for the time it will save you in the long run.

Calculating control surface loads is not currently a feature of MachUp. As far as I know, this is also beyond the scope of numerical lifting-line theory. What would be required is a knowledge of the control surface force per unit span as a function of angle of attack for each airfoil section used. And then some kind of integration scheme would have to be written in. Adding this would be far from trivial.

Sounds like a cool project! Again, if you're wanting to iterate with structural calculations, running MachUpX in Python will be your friend.

Thanks

Cory