EM Diagrams

[Tilt]

from the topic below I would like to find a range of EM diagrams but suspect they only exist for "certain" AC within AH.

I guess by filming standard manouvers and rechecking the  data this could be calculated...

except how do I determine a 400 ft turning circle............ any one got a terrain with rings painted on the ground?

any one derived standard tests?

any one got EM diagrams for the La7,La5FN and Yaks?

Tilt

[dtango]

Some of that information can't be emperically figured out via experiments but needs to be calculated- e.g. how do you figure out corner speed if this is only an instantaneous turn capability etc.  Another example- you can calculate turn radius in high loading  based on this formula:

TR = n (g-loading)/ velocity  
(I think that is the right formula)

I suspect that Badboy from the article mentioned has a method to grab the raw input for the AH aircraft and then cranks them through his formulas etc.

I've wondered about ways to build EM diagrams myself and have been referring back to the appendix in Shaw's Fighter Combat to try and figure it out.  The aerospace engineering is still just a little beyond me though to do much good with the stuff that he has.

I checked with Badboy about other EM charts.  He did say that sometime in the fall he had agreed to do EM charts for AH aircraft.  I've hunted high and low for EM charts for AH aircraft but haven't found any besides the ones mentioned in the article you are referring to.

[Tilt]

Originally posted by dtango:

TR = n (g-loading)/ velocity  
(I think that is the right formula)

Sorry I must be a bit dim..if g is expressed in newtons or kgM/sec^2 and we measure v in m/sec how does that derive an expression in m (metres). looks to me that the expression returns a figure in kg/sec. Unless the velocity was expressed as an angular velocity (degrees/sec) then we get a figure returned in kgM/degree sec.

It does seem we can measure linear velocity, G and (by filming and playback) time.

From the linear velocity (if constant) and time (to complete a circle or 10 circles)we can calculate a circumference and hence a radius. This seems pretty simple maths for sustained  TR tests at various velocities and g's. (choose a velocity, find the highest g at which you can sustain it in turn and measure the time per circuit... 10 circuits at 10m/sec in 1000 secs is a circumference of 1000 m and a radius of approx 160 metres)

having done that how would I determine the relationship between V, G, and TR (rate and radius) for instantanious conditions?

any ideas? is there a  relation ship between sustained and instantanious figures?

Tilt

[dtango]

Tilt:

That's a good point.  I was having trouble with it too!  The equation comes from Shaw though he mentions that it is a simplified mathmatical expression to demonstrate the proportionalities.  The equation in question is found in the appendix under the instantaneous turn performance section.

I'm out of ideas.  I hope someone else will answer.  I wouldn't mind working on EM charts with you if we could figure out how to do that!  There are some other resources that we should probably look at to help us.  I gotta go for the minute so I'll post some of that later.

[Badboy]

Originally posted by dtango:

I checked with Badboy about other EM charts.  He did say that sometime in the fall he had agreed to do EM charts for AH aircraft.  I've hunted high and low for EM charts for AH aircraft but haven't found any besides the ones mentioned in the article you are referring to.

Hiya,

Yep, I'm currently working with Andy Bush on a book sized project that should be complete by the end of September. Once that's out of the way, I will produce EM diagrams for all of the AH aircraft. I've already promised to do it, it's just a matter of time, and I'm looking forward to it.  

Badboy

[dtango]

I'm looking forward to those EM plots Badboy :-).

Tilt- meanwhile, here's some info that I've dug up that i think is useful.  There's others but I'll start with these two.

(1)web link to some good aerodynamics concepts:
 http://142.26.194.131/aerodynamics1/

(2)post contributed by Zigrat on AC aerodynamic computations: http://www.hitechcreations.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=9&t=001879

Email me at dytong@earthlink.net.  I would like to bounce some other thoughts off of you around the above.

[ 06-14-2001: Message edited by: dtango ]

[Badboy]

Originally posted by dtango:
I'm looking forward to those EM plots Badboy :-).

Me too  

Your first link doesn't work for me, is it broken?

Badboy

[dtango]

Badboy:

Keep trying it.  I have the same problem with it.  Sometimes it will hit.  Sometimes it won't.

[Badboy]

Originally posted by dtango:
Badboy:

Keep trying it.  I have the same problem with it.  Sometimes it will hit.  Sometimes it won't.

Thanks, it works now  

Badboy