Aerodynamics questions.

[Urchin]

Well, sort of a question.  Is there a good book I can pick up that will give me an idea of why planes perform like they do?  

I mean, explain stuff like this-

Spitfire out-turns the 109.  Everybody knows that.  But WHY could it out-turn it?  I mean, I guess I could give the answer I always hear, which is the Spitfire had a much better wing for turning than the 109, but are there more (or maybe better reasons?  Like, more in depth, explaining WHY the spitfires wing was better for turning and such.

Also, stuff like climb rate and acceleration and things- why do some planes climb really well and other planes climb really slow?  

Does weight effect turning?  

Would a really early 109 (like a 109E4) be able to out turn a late war Spitfire?  Or would the Spitfires wing still make it turn better?

Are there neat little formulas you can use to determine which plane will climb,turn, whatever better than another plane?

Just stuff I've always wondered, and more sense I started playing Aces High.  I've wondered it even more since the 109E4 got introduced- I thought the E4 would probably be a pretty good turner, especially against the comparitively late war N1K and the ever-present Spit IX.  But it can't out-turn them, so it is rather totally overmatched.  Could someone tell me why the N1K2 and Spit IX can out-turn the 109E?  I know the 109E was out-turned by the Spit I... but the Spit IX is heavier than the Spit I (which brings me back to, how much does weight effect turning?).  

Don't turn this into a "Luftwhiner" flamefest.. I'm just curious about why the good turning planes turn like they do.

[cajun]

I know a little about Aerodynamics. There is no one answer to why some planes turn better then others. It all depends on the design.  I don't know how much you know about aerodynamics but the basic concept of aerodynamics is air pushing against the plane or in most case plane pushing against the air. It is the same concept as ship.  The water causes drag and when you turn your rudder one way then it pushs against the rudder producing more drag on one side of the ship than the other causing it to turn.

If a plane has a bigger wing it will have more lift of course but because the wing is bigger more air will be pushing against it as it goes causing more drag and making it slower.

But because it has more lift it will be able to turn better (because turning is basically the same thing as climbing only sideways). Also weight is a factor with speed.  The heavier a plane is the better it will dive because of gravity, which is why the A6m is so slow.  But its light weight helps it climb very well.

The position of the wings also determine how well it climbs.  For example, if the wings are in front near the engine the plane will have more lift because its lifting up the heaviest part of the plane (the weight of the engine).  If it is further back, it will have less lift  but is faster because the front of the plane is heavier and gravity pulls it down more causing it to go faster.

I don't know how well I've explained it but maybe this will help give you an idea of how it works.  Most of what I know about aerodynamics I've learned on my own so its kind of hard to explain.

[Karnak]

A quick gestimate of an aircraft's turning capabilities can be gained by calculating its wing loading.

Find the sq.ft. area of the wing and then divide the aircraft's weight by that number.  The result is the pounds per sq.ft.  The higher the number, the worse the aircraft generally turns.

Climbing and turning are not the same thing.  Look at the Bf109G-10, Spitfire Mk XIV and A6M2.  The 109 and Spit will easily outclimb the A6M2, yet the A6M2 will easily out turn the 109 and Spit.  Power loading has a much greater effect on climb rate than it does on turn radius.

Another thing to not is the difference between turn radius and turn rate.  You can have one aircraft that takes longer to turn 360 degrees, but does it in a tighter circle, than another plane.  Each type of turn can be used to your advantage.

[Urchin]

No, I understand the basic concepts, like above.  Most of that is common sense, I think.  

I answered some of my own questions by grabbing a calculater and a bunch of my books.  

Some wingloading numbers:  (The formula I found was simply weight / wing area)

109E4:  Weight= 5,875 Lb
             Wing area= 174.05 Sq Ft
             Wingloading= 33.75 Lb/Sq Ft

Spit I:  (This is out of Spitfire: The History, which kind of confused me by listing the wingloading for the 1a as being 36 Lb/Sq Ft)
              Weight= 6,200 (3 Blade prop)
              Wing Area= 242 Sq Ft
              Wing Loading= 25.62 Lb/Sq Ft (which seems more normal)

Spit F IX : (see above)
              Weight= 7,295.5 Lb
              Wing Area= 242 Sq Ft
              Wingloading= 30.15 Lb/Sq Ft (which could explain why the Spit IX still out turns the 109E4)

A6M5:  (This is from Zero: Combat and Development etc. ad nauseum)
              Weight= 5,920 Lb
              Wing Area= 229.59 Sq Ft
              Wingloading= 25.8 Lb/Sq Ft

I also have Americas Hundred Thousand, which is a very good book.  It lists a section in the back that compares the turning ability of the planes included.  The list has the FM-2 (with a wingloading of 28.something, so it should turn good ), the P-61, P-63, P-51, P-47, P-38, F6F, and F4U-1d.  

The turning order goes like this (according to the book without flaps, which brings up another question)  Fm-2, P-63,P-61,F6F,P-51,P-38,P-47, and lastly, the F4U-1d.  Now, the wingloading of the F4U-1d and the F6F are practically the same (both 37.something).  The book mentions something about a 'lift co-efficient' of the wing as playing a large part in turning radius as well as wingloading.  How does one figure out this lift co-effecient of a wing (book doesn't explain that)?  The book says the lift coeffecient of the F4U's wing really sucks (paraphrasing lol) which is why it still can't turn even though it has pretty good wing-loading.  

Also, how big a part do flaps play in all of this?  I understand that they increase the surface area of the wing (although I don't understand HOW... they are already ON the back of the wing) thus increasing lift- but how much do they help?  

Also..  for another wingloading question.  The Zero book I have includes a section on flight tests between the Zero and various U.S. planes.  It has a very detailed part comparing the FM-2 and the A6M-5.  According to the book, the A6M5 could only gain 1 circle in 10 on the FM-2.  The wingloading difference is about 3 Lb/Sq Ft between both the FM-2/A6M5 and the 109E4/Spit IX-  but I think the Spitfire gains more than 1 circle in 10 (at least a good Spitfire pilot, I've outturned bad ones).  Is the Spits wing very good at creating lift (A high lift-coefficient I guess), and is the 109s wing very bad?

[Urchin]

Originally posted by Karnak
A quick gestimate of an aircraft's turning capabilities can be gained by calculating its wing loading.

Find the sq.ft. area of the wing and then divide the aircraft's weight by that number.  The result is the pounds per sq.ft.  The higher the number, the worse the aircraft generally turns.

Climbing and turning are not the same thing.  Look at the Bf109G-10, Spitfire Mk XIV and A6M2.  The 109 and Spit will easily outclimb the A6M2, yet the A6M2 will easily out turn the 109 and Spit.  Power loading has a much greater effect on climb rate than it does on turn radius.

Another thing to not is the difference between turn radius and turn rate.  You can have one aircraft that takes longer to turn 360 degrees, but does it in a tighter circle, than another plane.  Each type of turn can be used to your advantage.

Thanks Karnak, I was typing when you responded.  One question I'll ask that I can probably look up is about power loading.  What is power loading?  How do you figure it out?

Also, how can you tell which planes will complete a very tight circle but not get their nose around very fast (small turn radius but low turn rate) and complete very large circles quickly (large turn radius but fast turn rate).  

I DO understand that speed has a lot to do with it, I.E. you can force someone to turn a larger circle than you if they are going much faster.  But, assuming both planes are going the same speed, how can you tell which will have a better turn rate?  Turn radius is primarily a function of wing-loading, right?

[cajun]

Originally posted by Karnak


Climbing and turning are not the same thing.  Look at the Bf109G-10, Spitfire Mk XIV and A6M2.  The 109 and Spit will easily outclimb the A6M2, yet the A6M2 will easily out turn the 109 and Spit.  Power loading has a much greater effect on climb rate than it does on turn radius.

Very good point... But I'm not sure what you mean by "Power Loading"?

[niklas]

Originally posted by Urchin
Spitfire out-turns the 109.  Everybody knows that

Erwin Leykauf:

".....sometimes the slots would suddenly fly out with a bang as if one had been hit, especially when one had throttled back to bank steeply. Indeed many fresh young pilots, thought they were pulling very tight turns even when the slots were closed against the wing. For us, the more experienced pilots, real manoeuvering only started when the slots were out. For this reason, it is possible to find pilots from this period (1940) who will tell you that the spitfires turned better than the Bf109. that is not true, I myself had many dogfights with spitfires and could always outturn them.
One had to enter the turn correctly, then open up the engine. It was a matter of feel. When one noticed the speed becomeing critical - the aircraft vibrated - one had to ease up a bit, then pull back again, so that in plan the best turn would have looked like an egg or a horizontal elipse rather than a circle. In this way one could outturn the spitfire - and I shot down six of them doing it.
"

As you can see, it wasn´t always so clear which aircraft turned better.

niklas

[HoHun]

Hi Urchin,

the first thing you might want to look for is an explanation of "Energy Maneuvering".

Energy Maneuvering is a way of analyzing air combat that was invented in 1960s. The idea is to look at the power the engine provides and compare it to the power the manoeuvres eat up to see if you're winning or losing.

Wing loading was a key parameter in the 1940s' tactical concepts, but these were inaccurate and misleading. Wing loading is only useful if you're talking about aircraft with the same wing, like subversions of the same fighter.

Here's an example: The Spitfire I had an engine running on 87 octane fuel prior to the war. When the engine was changed over to 100 octane in 1939, it provided more power at the same weight. Wing loading didn't change, but with more power, the Spitfire could turn better, flying on the same turn radius at a higher speed.

Later, the Spitfire XIV replaced the Spitfire IX's Merlin engine with a much more powerful (and heavier) Griffon engine. Wingloading went way up, but so did power, and (according to a British test) the Spitfire XIV was able to turn just as well as the Spitfire IX with its lower wingloading.

Of course, there are different types of turns anyway. With the same wing, a lighter aircraft will usually be able to break-turn more rapidly before running out of speed or altitude. Again, wingloading is no safe indicator, though - the Fw 190D-9 could turn much harder than the Ta 152H which had a much lower wingloading, but has a lower G limit as its long wings would break at lower accelerations.

Once both aircraft settle into a sustained turn, though, the engine becomes as important as the wing for determining the turn rate.

Regards,

Henning (HoHun)

[niklas]

ups wrong thread sry

[SELECTOR]

i think i heard once that the spit turned so good because the wing flexed quiet a lot which in turn stopped the air becoming dead over the top of the wing which causes drag and eventualy a stall...where as the 109 had a very stiff wing which stalled quicker in a tight turn...

[Urchin]

Originally posted by HoHun
Hi Urchin,

the first thing you might want to look for is an explanation of "Energy Maneuvering".

Energy Maneuvering is a way of analyzing air combat that was invented in 1960s. The idea is to look at the power the engine provides and compare it to the power the manoeuvres eat up to see if you're winning or losing.

Wing loading was a key parameter in the 1940s' tactical concepts, but these were inaccurate and misleading. Wing loading is only useful if you're talking about aircraft with the same wing, like subversions of the same fighter.

Here's an example: The Spitfire I had an engine running on 87 octane fuel prior to the war. When the engine was changed over to 100 octane in 1939, it provided more power at the same weight. Wing loading didn't change, but with more power, the Spitfire could turn better, flying on the same turn radius at a higher speed.

Later, the Spitfire XIV replaced the Spitfire IX's Merlin engine with a much more powerful (and heavier) Griffon engine. Wingloading went way up, but so did power, and (according to a British test) the Spitfire XIV was able to turn just as well as the Spitfire IX with its lower wingloading.

Of course, there are different types of turns anyway. With the same wing, a lighter aircraft will usually be able to break-turn more rapidly before running out of speed or altitude. Again, wingloading is no safe indicator, though - the Fw 190D-9 could turn much harder than the Ta 152H which had a much lower wingloading, but has a lower G limit as its long wings would break at lower accelerations.

Once both aircraft settle into a sustained turn, though, the engine becomes as important as the wing for determining the turn rate.

Regards,

Henning (HoHun)

So what is 'power-loading'?  Wing-loading / horsepower?  It does make sense that a plane with more power but the same wingloading would turn better, I can't explain why but it makes sense intuitively.  

Just what role does 'power-loading' play in turning?  According to Karnak it plays a much greater role in climbing.  If power-loading is wing loading / horsepower, then that makes sense.  A small plane with a lot of power should climb faster than a big plane with the same power, because less lift is going towards holding the plane up.  Or is power loading weight / horsepower?  That would seem to make more sense than wing loading / horsepower, in light of a couple sentences ago.  

What I don't understand is how the Spit XIV could turn the same as the Spit IX.  It weighted 1,000 pounds more with the same wing.  For the Spit XIV to turn as well as the Spit IX (and having fought a couple I don't think it does, to be honest, at least not in AH) then power-loading would have to play a fairly significant role in turning ability (I think).  

Also, I'm having trouble with this.  The F4U-1D couldnt turn anywhere near as well as the F6F, in spite of having very similar wingloading and 'power-loading' (the planes weighed about the same and they had the same engine in them, so I hope the power loading is the same.. regardless of how you find it lol).  America's Hundred Thousand says the F4U wing had a poor "lift co-efficient"... but what does that MEAN?

[Karnak]

Urchin,

I may have used the wrong words.  I was quite tired when I posted that.  I merely meant lbs per hp as opposed to lbs per sq.ft. of the wing.

Power is more effective at increasing climb and speed than it is at increasing turn.  Cajun seemed to be indication that climbing capability was a indicator of turning capability, I was stating that it really wasn't.

[AmRaaM]

position of wing has nothing to do with lift potential. and wing loading is a very basic explanation of performance. the further back the position of the wing the greater the instability (a good thing for directional changes)ect ect ect... radi, root, e/drg coeff. ect combined  create  optimal performance.