Beginner's Guide to Aerodynamics

[funked]

Your tax dollars at work!
 http://www.grc.nasa.gov/WWW/K-12/airplane/short.html

Lots of good info in there about topics that I hear quite a few questions about.

It's designed for grades K-12 but that seems appropriate for you guys.
<G,D,R>
 

[GRUNHERZ]

Tho some are certainly closer to the K than the 12.  

[Jekyll]

Quick question for the aerodynamicists:

Fw190 was known to fly about 5 degrees nose low in level flight.  Now was this due to the lifting properties of the wing used, or was the 190 wing set at about a 5 degree angle of incidence to the fuselage datum line?

[funked]

Probably both Jekyll.

[juzz]

It's more like the cowling has a 5º slope, really.

[Jekyll]

 

Originally posted by funked:
Probably both Jekyll.

So funked, any idea why all 190s in AH ride about 5 degrees nose UP for level flight at any altitude above 10k in AH?

I mean, if HTC has correctly modelled the wing incidences of the 190s, that means that in level flight the AH 190 wing is ALREADY at about a 15 degree AOA.

[funked]

I don't have adequate tools for measuring the pitch angles of the 190 in flight in AH, I don't have an adequate historical reference on what the pitch angles were, and I don't have enough data on the plane to calculate them.

FYI the lift coefficient of the aircraft is a linear function of the pitch angle in level flight (i.e. angle of attack).  So pitch angle will vary inversely with the square of IAS in level flight.  A figure "5 degrees" is meaningless without an airspeed.

PS Remember the wing is not the only thing giving lift.  The horizontal tail, fuselage, and propeller all make contributions.

[This message has been edited by funked (edited 05-07-2001).]

[R4M]

 

Originally posted by juzz:
It's more like the cowling has a 5º slope, really.

nope, the Fw190A had a noticeable "nose down" attitude in flight.

I think that in AH this is modelled in the lfying ( you can notice it in the external view), but not from the cockpit.

I think that this is also the reason because the D9 doenst hit squat with its wing cannons. the D9 flew with a "straight" attitude,and so does in AH. but I think that the cannon elevation in the wing has NOT changed its elevation to compensate, and so the cannons fire too low. At least that is my perception.

[funked]

I really doubt the thing actually flew with the thrust line (propeller axis) inclined downward.  That would mean that the wings would have to create extra lift (and drag) to counteract the downward thrust component.  If it were true it would be a very significant performance-robbing design mistake.

[Nashwan]

 

I think that this is also the reason because the D9 doenst hit squat with its wing cannons

It's maintaining a 1.5 to 1 k/d ratio using only 2 MGs? PERK IT  

[Jekyll]

 

I really doubt the thing actually flew with the thrust line (propeller axis) inclined downward. That would mean that the wings would have to create extra lift (and drag) to counteract the downward thrust component. If it were true it would be a very significant performance-robbing design mistake.

Of course, that's assuming that the thrust line is exactly parallet to the fuselage datum line.  If however the thrust line were inclined upwards at 5 degrees to the fuselage datum line, with a wing incidence of + 5 degrees, would not the aircraft fly straight and level with a 5 degree nose low attitude?  (all other things being equal of course)  

Anyone got any thrust line/wing incidence data on the 190 series?  It's an interesting question as to why KT designed a fighter that flew like that.

[Flitze]

The wings of planes are often attached in a way that the fuselage has the minimum amount of drag at the most common speed and load. And most times, that's at cruise speed to maximize range, not at top speed. Look at the wings of the bombers or, similar, the missile mount on the wingtip of the F18, which is attached in an slightly negative angle to minimize drag at cruise speed.

[Bodhi]

Well considering that our FW-190F8 has a fairly neutral incidence, I find it hard to believe that they flew 5 degrees down in a level flight attitude.  My personal opinion on it, is that the flight attitude is being misread owing to the cowling.