Maybe the 190s arent wrong....or how to be really unpopular in 1 step

[Crumpp]

Guess you don't get that whole "fundamental relationship of" portion underlined, Angus.

As the exerpt I posted states turning is much more of a general problem.  There are many factors that go into it and many shortcuts to estimate turn performance.

However as this engineering text states,  they are each in turn derived from fundamental relationship of thrust required and available or power required and available for various angles of bank.

http://img14.potato.com/img.php?loc=loc129&image=8eb5a_turnperformance.jpg

http://img11.potato.com/img.php?loc=loc146&image=03566_PaequalsPr.jpg

AFAIK there was not one single WWII fighter with the power to fly at CLmax in a sustained turn.  

All the best,

Crumpp

[Grits]

What I find interesting about those two aircraft reports is they seem to be contradictory. One says the P-47 pwns the 190, the other says the opposite.

[Angus]

Crumpp: You either did not read my text properly, or it is you who does not understand the fundamental issues.

With the same airframe,wing, and same power, increased weight, and thereby wingloading will ABSOLUTELY affect turn ability, in a negative manner.

(As well as climb, top speed, acceleration, partially zoom, - basically everything except dive and terminal velocity)

RIGHT?

[justin_g]

AFAIK there was not one single WWII fighter with the power to fly at CLmax in a sustained turn.

Ehh? So no ww2 fighter could sustain a level turn at the edge of a stall? WW2 fighters had enough power to climb in a CLmax turn - eg: 109 spiral climb!

The turning circles of both aircraft are identical. The Spitfire XIV appears to turn slightly better to port than it does to starbord. The warning of an approaching high speed stall is less pronounced in the case of the Spitfire Mk XIV.

How can turning circles be "identical" when they admit that the XIV turns better to port. The IX would turn better to starboard, because the engine rotates in the opposite direction. Perhaps the XIV could match the IX in left turns - best XIV turn, worst IX turn. They mention this difference in other comparisons:

Spitfire XIV can easily turn inside the FW 190, though in the case of a right-hand turn, this difference is not so quite pronounced.

If we look at the Spitfire V vs IX trial, we see this:

The Spitfire IX was compared with a Spitfire VC for turning circles and dog-fighting at heights between 15,000 and 30,000 feet. At 15,000 feet there was little to choose between the two aircraft although the superior speed and climb of the Spitfire IX enabled it to break off its attack by climbing away and then attacking in a dive. This manoeuvre was assisted by the negative 'G' carburettor, as it was possible to change rapidly from climb to dive without the engine cutting. At 30,000 feet there is still little to choose between the two aircraft in manoeurvrability, but the superiority in speed and climb of the Spitfire IX becomes outstanding. The pilot of the Spitfire VC found it difficult to maintain a steep turn without losing height, whereas the pilot of the Spitfire IX found that he had a large reserve of power which enabled him to maintain height without trouble. The all-round performance of the Spitfire IX at 30,000 feet is most impressive.

Here we see the benefit of having greater excess power - at high alt the IX can maintain an angle of bank that the V cannot.

Also, note that the V and IX have "little to choose" in turning circles. V=IX, IX=XIV? So the (2,000lb/30% heavier XIV actually turned as good as a V!;)

[Crumpp]

Also, note that the V and IX have "little to choose" in turning circles. V=IX, IX=XIV? So the (2,000lb/30% heavier XIV actually turned as good as a V!

I find it funny that the entire FW-190A series gained much less than that and just as much power yet is seen as become "piggish" in it's handling.

None of the Focke Wulf pilots who flew the FW-190A8 felt that way or related that to me.  When asked they all loved it in comparison to other Antons.

Only the R7/R8's were seen as having poor handling.

What I find interesting about those two aircraft reports is they seem to be contradictory. One says the P-47 pwns the 190, the other says the opposite.

One is for a P47C the other is a P47D4 using water injection and mounting the paddle blade prop.

All the best,

Crumpp

[Crumpp]

With the same airframe,wing, and same power, increased weight, and thereby wingloading will ABSOLUTELY affect turn ability, in a negative manner.

Sure unless a corresponding increase in power occurs.  I don't think anyone has disputed that in this thread so I am confused as to why you posted it.

WINGLOADING HAS EVERYTHING TO DO WITH ITS EFFECT ON TURN RADIUS!

Actually what is important is not the wingloading increase but the reduction in excess power.  Adding weight has the effect of increasing power required and reduces powerloading.

All the best,

Crumpp

[Angus]

Stack up the best turners of WW2 fighters - you will find out it has almost a paralell list as their wingloading tables.
So it also does in AH.

Oh and this:

"--------------------------------------------------------------------------------
With the same airframe,wing, and same power, increased weight, and thereby wingloading will ABSOLUTELY affect turn ability, in a negative manner.
--------------------------------------------------------------------------------



Sure unless a corresponding increase in power occurs"


Did you read:
"same power" above??????

[bozon]

In principle, Crump is right - In practice he is wrong.
Given enough power loadaing you can hang on the prop and rotate on the spot. It's called a helicopter. When you do not have enough power loading to hover, you need speed and fixed wing lift. You want the smallest speed but on the other hand to produce minimum drag. So you want a wing whose induced drag will not be too high at slow speeds, but still produce enough lift to keep you flying - meaning high aspect ratio + less AoA - meaning more area.

Try turning in a glider - it turns really tight and looses very little alt/speed. Just a small engine would give enough power to keep it level. It's wing efficiency, loading and power loading all mixed.

Bozon

[Crumpp]

In principle, Crump is right - In practice he is wrong.

I hardly think Perkins & Hage is wrong.

It is an engineering test about fixedwing aircraft design.  

Try turning in a glider - it turns really tight and looses very little alt/speed.

It still looses......

No way around it.

However improve the power available to power required and:

Just a small engine would give enough power to keep it level.

And you prove the point in practice.

Stack up the best turners of WW2 fighters - you will find out it has almost a paralell list as their wingloading tables.

It's obvious some people are reading into this and fearing for a game shape.  As the text states, there are numerous methods of estimating turn performance.  However turning is a fundamental function of power required to power available.

As demonstrated by flight testing, a moderate increase in wingloading can be overcome with a corresponding increase in thrust.  Hence the improvement in the P47's turning ability with the High Activity Propeller.  And of course the Spitfire flight testing mentioned above or the F18/F16 trials.
 

All the best,

Crumpp

[bozon]

Actually what is important is not the wingloading increase but the reduction in excess power.

power required to power available.

I believe those are your own words that I copied and pasted. Bigger and more efficient wings means less power required, therefore more power available. You may claim it is weakly dependent on the wings, but it still is.

It is nothing short of a miracle (no kidding), but it is possible to fly with an engine that produce less thrust than your plane weights and manuver with it. The minimum requirement is wings. This means that wings are more efficient in keeping the plane in the air than pure thrust vectoring.

Also notice that on the page you posted (Airplane preformance p.202) it says:
"It is shown in figure 4-1d that minimum radius in level flight accures at the CLmax provided PA>PR".
First, figure 4-1d is not on this page. Second, while minimum radius is achieved at CLmax, it doesn't say anything about its value. Third, as you can see, at the slower side of the drag curve, what eats your power is the induced drag which is dominant over the viscous drag. Increasing wing size and efficiency (aspect ratio etc.) will reduce the induced drag at a given speed for a small cost in viscous drag. Of course you can't go too far with that since at some point viscous drag will be so high it will not be worth the tradeoff (not to mention the weight of the wings themselves).

Bozon

[Angus]

Hehe, Crumpp:
"a moderate increase in wingloading can be overcome with a corresponding increase in thrust"

Moderate yes. The tendency was normally within WW2 fighters, to lose turning ability while getting better climb and top speed.

A Spit I outturns a XIV, a 109E outturns the K and so on.

There are exceptions, 109F turned equal to or better than the 109E and so on. Or maybe it isn't an exception, have to look at the wingloading, for the 109F has some lighter parts?!?!

A boosted Spit IX will outturn a none boosted one (since the boosting in that case doesn't come with a weight penalty) and so on.

But Generally, - to put it simple, -  wing loading.

And then the little odds and ends.

On gliders, the span loading is also very favourable

[Crumpp]

Angus,

FACTS are the Spitfire was able to compensate for the 5lbs wingloading increase.  You cannot get around the fact that in the air, the aircraft were seen as having identical turning ability by the RAE test pilots.

The FW-190 series only gained 3 lbs and just as much power as the Spitfire series.

Why is the FW-190A8 such a pig in AH?  What is the scientific basis?  While it is a common perception that the aircraft gained weight and no power.  That is not the case at all.

bozon,

Third, as you can see, at the slower side of the drag curve, what eats your power is the induced drag which is dominant over the viscous drag.

You’re correct that induced drag is the dominant force at low speed.  However do not confuse coefficients and force with power.

While the cooefficient of inducued drag will gradually increase the slower the aircraft, the power application is different.

http://www.av8n.com/how/htm/4forces.html#fig-coeff-ias

The force of induced drag also rises along with the coefficient.

http://www.av8n.com/how/htm/4forces.html#fig-force-ias

However the power of induced drag rises very little.  It's power comes on very rapidly like a wall and not a gradual tug that increases.  The wall occurs after CLmax on the backside of the polar at the stall.

In the mushing regime, most of the drag is induced drag. As you go slower and slower, induced drag increases dramatically and parasite drag becomes almost negligible.

http://www.av8n.com/how/htm/4forces.html#fig-power-ias

Additionally, designers have been well aware of the benefits of reducing induced drag and ways to manipulate wing efficiency since the 1930's.  The differences in WWII fighter wing efficiency are imperceptible in the air.

A square-tipped rectangular wing is almost as efficient as the elliptic wing.

http://www.centennialofflight.gov/essay/Theories_of_Flight/Reducing_Induced_Drag/TH16.htm

The induced drag is a completely seperate subject and should not be the focus of this thread.  I suggest a new thread to cover this subject or feel free to PM me.  We can discuss it and summerize the results.

It is nothing short of a miracle (no kidding), but it is possible to fly with an engine that produce less thrust than your plane weights and manuver with it.

Yes it is and engines have produced less thrust than the weight of the plane for the vast majority of the time man has been using heavier than air flight.

Second, while minimum radius is achieved at CLmax, it doesn't say anything about its value.

It's not talking about a specific plane, it is referring to all aircraft.  CLmax will change too with conditions.

You may claim it is weakly dependent on the wings, but it still is.

Nowhere do I claim it is weakly dependant upon wings.  I claim the fundamental relationship is not derived from wings.  It is derived from power available to power required.

Even a Glider uses this relationship.  It must be towed to altitude where it converts the potential energy it stored during the tow to kinetic energy for flight.

To focus solely on wing loading is incorrect.  Wing loading is nothing more than one of many shortcuts of estimating this relationship.

Just as Perkins & Hage state.

It is a fact that a wing loading increase can be overcome with thrust.

All the best,

Crumpp

[hitech]

Gentlemen you will have better luck in this discusion if you seperate the two concepts.

Turn Radius.

Turn Rate.

HiTech

[Crumpp]

But one most certainly effects the other.

Rate is a function of velocity and the angle of bank at Pr = Pa.  

Although angle and velocity for minimum time will not be the same as for minimum radius,of course.

It still remains a fundamental relationship of Power required to Power available.  It does not change the fact a thrust increase can overcome a wingloading increase.

All the best,

Crumpp

[Angus]

CC HiTech, see what you mean. All a matter of velocity in the turn so a wider turn may still be faster around the dial. (More G then).

Anyway as a sidenote was fighting 190A5's with a Spit V yesterday.
Must say that a correctly flown 190 will give the Spitty a hard bird to catch.
Did not seem to be too off for my taste the only way to catch a 190 was with superior alt or if they could be forced into slow maneuvers.

I clobbered one in a Hurricane though