"Four forces" software - opinions sought

[CBLong]

Having read several threads on this fine board about the famous 'four forces' and all the surrounding topics, I thought it would be useful to have some software to allow investigation and visualisation of the 'four forces' under various flight conditions. I couldn't find any such software on the net, so I've started rolling my own... I'd be very interested in hearing opinions from flying instructors as to whether this idea is worth pursuing as a teaching aid (or any other purpose). I think it could be useful (when sufficiently developed) for demonstrating that (eg) lift is less than weight in the climb, etc.

If you'd like to have a play, the program is available for download here: http://www.oview.co.uk/fourforces/fourforces.exe . It'll run on any recent Windows (Win95/98/2k/ME/XP etc) and doesn't require any fancy graphics hardware or anything. It's about 80K to download. (Standard disclaimers apply - I've got no reason to suspect that the file carries a virus or has any potential to do any damage, but you download at your own risk etc.)

There's no installation - just download it and then double-click on the fourforces.exe file from Windows Explorer.

Select "Help | About" for some instructions, but basically you can control the pitch angle of the aircraft by pressing the 'A' and 'Z' keys, and the engine power using the '<' and '>' keys (unshifted).

The three black lines represent lift, drag and weight, the green line is thrust, the red line is the resultant force, and the blue line is the velocity... (this should make sense as and when you run the program!).

This is very rough and ready at the moment - I don't want to waste too much time on it if it's not going to be useful - so any feedback would be much appreciated. Reply here, or mail [email protected] if you prefer.

Thanks!

cbl.

ps I should probably point out - it's not my intention for this to be a commercial product - this and any later versions will remain free downloads. I just enjoy the programming, and hopefully it'll be useful in some way...

[EightsOnPylons]

Very nice programming there CBL! Very Cool!

Just some comments:

I took the plane into a stall and then I couldn''t recover. I tried this several times. Maybe I am doing something wrong. I get a descent 18000 feet per min. Since I have a european keybord I dont think I can adjust the power?

great work!

[CBLong]

Hi Eights,

Thanks for the feedback! You should be able to recover it from the stall simply by pitching down (ie pressing and holding the 'A' key) - it won't pitch down by itself because the program currently holds the aircraft at a constant pitch attitude all the time (unless you adjust it manually by pressing 'A' or 'Z'). These screenshots show how it works for me:

(1) Just stalled (pitch attitude is about 7 degrees or so nose-up, the simulation has a max Cl at 12 degrees AoA):

http://www.oview.co.uk/fourforces/ff_stall.gif

(2) Recovering (press and hold 'A' until you get 45 degrees(!) nose-down):

http://www.oview.co.uk/fourforces/ff_recover.gif

(3) Once you're flying again, pitch up (press 'Z') to get back to straight and level:

http://www.oview.co.uk/fourforces/ff_level.gif
I plan to add properly-simulated pitch-axis rotation in the future - but this 'pitch-hold' version is quite fun to play with too!

Cheers,

cbl.

I forgot to add - to control the power, press the ',' (comma) key to decrease power, and '.' (full stop, or period) to increase power. On a UK keyboard, these keys correspond to the '<' and '>' keys, although you shouldn't press Shift... (it seemed intuitive at the time :)

cbl.

[EightsOnPylons]

Thank you very much for your explanation! Now it works well! I was thinking: is it possible to add a quick explanation in the one corner. something like

red=drag
blue=

and so on.. maybe it will be easier to get a fast overwiev of how it works and what it displays?

I think you have done a great program! Keep up the good work CBL!

[Aussie Andy]

CBLong - Excellent... I think what it needs most is a power indicator, whether from 0% to 100% or from 0 to 2600rpm or whatever... as it is, you can't select a power level back to a known starting point.

I reckon its a useful training aid... I'm not an instructor though.

[EightsOnPylons]

That sounds like a great idea! Looking forward to seeing it implemented if possible.

[Flyin'Dutch']

Hi CBlong

That is good fun interesting to do stalls the AoA only really changes at the very last moment and the fact that it is well above the 15 degrees for quite a well than most may think.

FD