Dora stall speed

[Yo-Yo]

What corner speed should I maintain in the 190 to out turn the P-51 ingame Crumpp?

 

What turn do you want? Instanteneous or sustained? The answer will be different.

[Crumpp]

Горизонтальный полет. Самолет устойчив во всем диапазоне скоростей. На максимальной скорости поведение самолета нормальное. Минимальная скорость 210 км/ч (по прибору).

 

Is that stall speed or just the front side of the power curve? That falls in the vicinity of where the power curve changes in my estimation and most aircraft exhibit some instability on the backside.

 

Reason I ask is it that is not very good agreement with the RAE findings or the vicinity of Vs1 (94.4KEAS) using Focke Wulf's CLmax of 1.58.

 

 

530

 

That is the landing roll, right? 530Meters.

 

3800

 

Weight the numbers are corrected too, right?

 

3800Kg = 8377.6lbs

 

 

That is 15% error over what Chuck Yeager the perfect test pilot with maximum braking application could do. Good flying considering that pilots experience in an FW-190! It is very plausible.

 

Let's see what our CL has to be for a landing speed of 154KpH IAS =

 

Whew...that is off the PEC charts....

 

Ballparking ~ -10mph PEC correction

 

154Kph IAS = 95.69mph IAS - 10mph PEC = 85.69mph CAS

 

85.69 mph CAS * .869 = 74.4KEAS

 

A 8377.6 lbs Aircraft traveling at 74.4KEAS needs:

 

q = 74.4KEAS^2/295 = 18.76p/ft^2

 

CL = Weight/(q*S) = 8377.6lbs/(18.76p/ft^2*235.75ft^2) = 2.26

 

That is in the ballpark of a split flap system.

 

IMHO, that makes it really unlikely the 1.58 is the CL max of the aircraft with landing flaps deployed for the performance calcs used on Weiderstandaten von Flugzeugen.

Edited October 8, 2015 by Crumpp

[Crumpp]

THis is Russian report on the 190.

 

Minimal speed (gauge reading) is 210 kph.

 

There is a landing speed observation WITH KNOWN MASS.

 

Thank you for sharing, btw! :thumbup:

[Hummingbird]

What turn do you want? Instanteneous or sustained? The answer will be different.

 

Indeed, but I thought I hinted at that by asking what speed I should maintain :) i.e. I was refering to the sustained turn rate :)

[Crumpp]

What Yo-Yo says...

 

I read too far back on the curve.

Edited October 8, 2015 by Crumpp
see above

[Yo-Yo]

Indeed, but I thought I hinted at that by asking what speed I should maintain :) i.e. I was refering to the sustained turn rate :)

 

At the best (320-350 kph) turning speed Dora is equal to P-51 in sustained turn. At SL, i mean, but the parity will depend on altitude because of different power curves. At higher speed Dora performs better turn but you have to force P-51 to turn at these speeds. :)

[Crumpp]

At the best (320-350 kph) turning speed Dora is equal to P-51 in sustained turn. At SL, i mean, but the parity will depend on altitude because of different power curves. At higher speed Dora performs better turn but you have to force P-51 to turn at these speeds.

 

Or the P-51 slows down to match the Dora's turn rate. :smilewink:

 

He can neutralize the turn advantage but at the cost of speed.

 

There is a reason why fighter pilots say, "Speed is Life".

[Yo-Yo]

By the way, Crumpp, have you seen NACA TN 1044?

[Crumpp]

By the way, Crumpp, have you seen NACA TN 1044?

 

Got it.

[Crumpp]

Interesting conclusions!

 

I hope you model the characteristics of the NACA 23015 at high alt / mach. The FW-190 was not a high altitude fighter, even with a better engine.

 

http://www.wwiiaircraftperformance.org/fw190/Fw_190_Dive.pdf

 

http://www.wwiiaircraftperformance.org/fw190/fw190-0022-dive.html

 

See how the aircraft is porpoising at 9000 meters:

 

http://www.wwiiaircraftperformance.org/fw190/Fw_190_0022-Dive-2.jpg

 

Notice the high mach stall of the F6F....

 

The FW-190 seems to be very similar.

[Yo-Yo]

Interesting conclusions!

 

I hope you model the characteristics of the NACA 23015 at high alt / mach. The FW-190 was not a high altitude fighter, even with a better engine.

 

http://www.wwiiaircraftperformance.org/fw190/Fw_190_Dive.pdf

 

http://www.wwiiaircraftperformance.org/fw190/fw190-0022-dive.html

 

See how the aircraft is porpoising at 9000 meters:

 

http://www.wwiiaircraftperformance.org/fw190/Fw_190_0022-Dive-2.jpg

 

Notice the high mach stall of the F6F....

 

The FW-190 seems to be very similar.

 

Yes, as well as the Mustang. As you can see the tales about "poor CL max" of laminar airfoil are only tales because at average M CL of P-51 has a shelf and other conventional airfoils have monotone slope.

[MiloMorai]

Or the P-51 slows down to match the Dora's turn rate. :smilewink:

 

He can neutralize the turn advantage but at the cost of speed.

 

There is a reason why fighter pilots say, "Speed is Life".

 

Or the P-51 can do another type of turn that is not horizontal. Might even come out of the turn with a little more speed.

[Hummingbird]

Yes, as well as the Mustang. As you can see the tales about "poor CL max" of laminar airfoil are only tales because at average M CL of P-51 has a shelf and other conventional airfoils have monotone slope.

 

Again this is based on a perfectly smooth airfoil, which no P-51 ever had. Under real life conditions the laminar flow airfoil performs noticably worse in CLmax than the NACA 23xxx series, as evidenced by NACA tests on that specific subject.

 

David Lednicer made a comment about a while back as well I remember.

[Crumpp]

Yes, as well as the Mustang. As you can see the tales about "poor CL max" of laminar airfoil are only tales because at average M CL of P-51 has a shelf and other conventional airfoils have monotone slope.

 

Laminar flow airfoils are very misunderstood subject when it comes to airfoils and flight sims.

 

Laminar flow is a high speed/cruise range event. It is not a high angle of attack occurrence.

 

For the readers...the red box is the drag bucket. Notice the Coefficient of Lift it corresponds too.

 

 

Now Laminar flow is very sensitive to fit and finish. One of the aircraft at work even as "bug scale" the mechanics have to use to count the smashed bugs on the LE of the wing. If it has too many, they have to be removed.

 

Even then, the plane will fly fine, it just won't get the benefits of laminar flow in cruise flight.

 

Did I give you a copy of David Lednicers Computational Flow analysis of the P-51?

AIAA-2009-623-922.pdf

[Crumpp]

Or the P-51 can do another type of turn that is not horizontal. Might even come out of the turn with a little more speed.

 

Sure can...

 

The point is the math shows the airplanes to be very even dogfighters no matter which method is used to determine that performance.

[Crumpp]

Here is David's presentation to the AIAA. He does a nice round up of all the aeronautical research on the design.

AIAA913288.pdf

[Hummingbird]

NACA 66(1)-212

NACA 23012

[Yo-Yo]

Here is David's presentation to the AIAA. He does a nice round up of all the aeronautical research on the design.

 

For those who can understand graphics - good picture to show how power-on conditions reduces longitudinal stability and add pitch-up moment at high AoA (CL). :)

[Crumpp]

Hi Hummingbird,

 

My hope is to ensure there is no misunderstanding about the effect of laminar flow.

 

As I said, laminar flow is a low angle of attack phenomenon and has no effect on high angle of attack flight.

 

I think what confusing is the fact that low drag does equal low lift. Drag and Lift are connected by a fixed and direct relationship. When one goes up, the other also increases. Consequently, when the airfoil reaches the drag bucket, the drag goes down and so does the lift.. Outside of that drag bucket, it is a normal airfoil.

 

Do I believe an operational P-51 developed laminar flow?

 

No, I do not. Laminar flow requires a very clean finish that is unlikely to be maintainable in the field. Keeping laminar flow wings maintained requires careful attention to surface fit and finish.

 

Most measured evidence on the P-51 series supports this conclusion.

 

What is the effect of the P-51 series not developing laminar flow as designed?

 

The aircraft burned more gas getting to the target and took a minute longer.

 

In the airlines, the airplane does not get grounded if it does not pass the bug test, it just gets cleaned up at night.

 

What does laminar flow have to do with dog-fighting in DCS?

 

Nothing unless we want to cruise for a couple of hours.

[Crumpp]

For those who can understand graphics - good picture to show how power-on conditions reduces longitudinal stability and add pitch-up moment at high AoA (CL). :)

 

да, да!

 

[Hummingbird]

What I'm trying to get across is that the sharper leading edge of the laminar flow airfoils decreased the CLmax compared to the rounder LE of the more conventional airfoils, esp. under operational conditions and at high AoA. In addition to this stalls were more abrupt with less warning, again due to the sharper LE.

 

i.e. the only advantage of laminar flow airfoils on operational aircraft was in straight flight as the air resistance is reduced, much like the sharpening of the point of a bullet reduces drag just the same, and even more so if you taper the end as well.

 

Hence why the NACA 6 digit series showcased worse CLmax than the NACA 23xxx series in NACA's own testing, however also noticably lower drag in straight flight.

 

The lift disadvantage of laminar flow airfoils was removed with the use of high lift LE devices such as slats and/or the camber changing LE flaps which alter the AoA of LE to the airstream.

Edited October 9, 2015 by Hummingbird

[NineLine]

Again this is based on a perfectly smooth airfoil, which no P-51 ever had. Under real life conditions the laminar flow airfoil performs noticably worse in CLmax than the NACA 23xxx series, as evidenced by NACA tests on that specific subject.

 

David Lednicer made a comment about a while back as well I remember.

 

Yo-Yo has already stated that the information he was working with showed flight testing and wind tunnel testing were comparable, not sure this whole notion of the "perfectly clean airfoil" needs to be brought up all the time in numerous threads.

 

Take the OP for what is was, a dogfight, not testing and comparing turn rates, too many factors in there to be making blind assumptions.

[Hummingbird]

Yo-Yo has already stated that the information he was working with showed flight testing and wind tunnel testing were comparable, not sure this whole notion of the "perfectly clean airfoil" needs to be brought up all the time in numerous threads.

 

This is where I disagree however as I see flight testing disproving it.

 

Take the OP for what is was, a dogfight, not testing and comparing turn rates, too many factors in there to be making blind assumptions.

 

I agree, and like you I haven't had issues outturning -51's in the 109 ingame either, I'm just commenting that something is out of whack if it was otherwise.

[NineLine]

This is where I disagree however as I see flight testing disproving it.

 

Point is that ED has already addressed your concerns, you dont have to agree, but repeating it over and over in different threads isnt getting you anywhere.

[Hummingbird]

I shall let it rest SiTh.