A tool for JSBsim Airfoil Modelling

[123apple]

Not too sure, really. Maybe it needs an initial value?

[IAHM-COL]

that works. The init value is Centigrades or Farenheit or doesnt matter?

[bomber]

It's in degrees F

Fuel Temperature:
Fuel temperature is calculated using the following assumptions:

Fuel temperature will only be calculated for tanks which have an initial fuel
temperature specified in the configuration file.
The surface area of the tank is estimated from the capacity in pounds. It
is assumed that the tank is a wing tank with dimensions h by 4h by 10h. The
volume of the tank is then 40(h)(h)(h). The area of the upper or lower
surface is then 40(h)(h). The volume is also equal to the capacity divided
by 49.368 lbs/cu-ft, for jet fuel. The surface area of one side can then be
derived from the tank's capacity.
The heat capacity of jet fuel is assumed to be 900 Joules/lbm/K, and the
heat transfer factor of the tank is 1.115 Watts/sq-ft/K.
Fuel temperature is currently not written to the property tree.

This last sentence might be important I'm thinking

[123apple]

I can assure you it is... I use that property.

[bomber]

wiki needs updating then.

http://wiki.flightgear.org/index.php?ti ... ile_Format

[bomber]

Would some of these differences raise an immediate flag for you, or is more like test on perfomance and see?

On the Ask13 it changed the Lift2Drag from 27.5:1 to 25:1.... adjusting the front fuselage drag down from 0.15 to 0.095 brought it back to 27.5:1

[IAHM-COL]

were you able to execute the airfoil code?

[IAHM-COL]

I can assure you it is... I use that property.

@123apple

Thanks for the pointers.
I tried using that property, and it works to set up the temperature of fuel, but it has some problems I couldn t figure out how to work around, and were prohibitive for my intentions.

Firstly, the initial value. JSBsim only accepted a numeric value, and not, per example a property.
The problem? well, can someone explain me how the fuel temperature begins at 50F if the plane is parked on Siberia in Christmass?
I tried setting the environment temperature property for initial parameter. JSBsim laughed at me.

Secondly, the property generated there by JSBsim is completely internal. ie, I can't modify the value obtained dynamically on execution. Clearly, not only I can't set my environment temperature after initialization, but even more critical, it forbade my trying what I really want to do with the fuel temperature, and that is implementing a FCOC for my fuel's systems. In such system, the oil temperature heats the fuel simmultaneous as thermo diffusion chills the fuel through environment transfer on the tanks. At the same time, off course, thermotransfers are bilateral, which lead to oil cooling via the fuel transition throught the coils.

To do so, I needed to be able to implement changes on fuel temperature. A property that JSBsim completely hog wasn't going to help me


I thus, implemented functions of heat transfer given

Code: Select all

deltaQ/delta-t = -KA deltaT / delta distance

and tried estimating values that give me logical temperature balance at the begining. I'll need to test how it behaves as temperatures change (like cold high alt and stuff).


Anyhow, thanks for your input and help,

Best,
Ih-COL

[bomber]

were you able to execute the airfoil code?

Not at present, I'm trying to not get too distracted from what I'm doing right now..

I started this thread in 2007 which Thorsten trashed in his own unique way. Nothings been done in FG in the 12 years since (even tho people understood Thorstens method) and I'm just finishing off my code to resolve it as it's needed for the Spitfire to perform correctly.

https://forum.flightgear.org/viewtopic. ... h&start=30

Once I've nailed this I'll get back to this tool and use it to look at any differences in my original method with regards the Spitfire wings.

regards

Simon

[IAHM-COL]

Not at present, I'm trying to not get too distracted from what I'm doing right now..

copy that.

Anyhow, Thorsten?! He should get back to the clouds!! (hahah)