Author Topic: F4u flaps  (Read 6909 times)

Offline Knegel

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« Reply #45 on: November 17, 2006, 02:37:07 PM »
Quote
Originally posted by Squire

Also, wing loading is wing loading, and the F4U had a higher wing loading than many lighter WW2 fighters. Higher wing loading means at a given G, you lose speed faster than a fighter with a lower wing loading. So a Spit IX pulling 5 Gs will say, drop 50mph after one 360 turn, where an F4U would drop 75mph, pulling 5 Gs (assuming same E state and alt). < Just an example, I dont have the data in front of me. The F4U would need to drop to a 4 G turn to remain the same speed, thus the 5 G Spit eventually "out turns" him, thats the mechanics of it.

...and Im not just picking on the F4U, like I say I think the flaps code in AH needs looking at with all of them.


Hi,

actually its the other way around at same G´s!!

If lets say a 109F4 and a SpitVb turn both with 5G´s, it depends to the inertia(spanload), propeller thrust and other wing design factors(wing aspect ratio, airfoil ), which of both decelerate faster.

The reason why many people get confused is the fact that the more heavy wingloaded plane tend ot need a more big AoA to gain the same G load or tunrradius  than the more light wingloaded plane. What most people dont see is the fact that the more heavy wingloaded plane have a smaler relative wingarea. As result, while turning, planes with similar weight(109F4/SpitVb) show a very similar wingarea into flightdirention. The big wing of the Spit need a smaler AoA, while the smal wing of the 109F4 need a more big AoA.

In general planes with heavy wingload tent to keep more energy as faster the planes fly and and/or a smaler the AoA is, while planes with a low wingload tend to be able to turn more tight.

But this depends much to the wingdesign. A wing with a high aspect ratio tend to produce more lift and smaler drag at high AOA than a wing with smal aspectratio. As result the wingarea of a high aspectratio wing can be smaler to arcive the same lift like a more big wing with smal aspectratio.

In your example the F4U for sure will get faster out of the 5G 360° turn than the Spit(only a Spit14 probably could keep up).

Why?? Cause the F4U had MUCH more inertia and MUCH more power.

Same count for the FW190A vs a SpitV and P38 vs A6M2.

The more light wingloaded planes(lets assume they are also more light liftloaded) can turn more tight where the heavy liftloaded planes already stall, and they also have advantages while a sustained turn(but this depends much to the powerload), as faster the planes fly, as less advantage the relative big wings  bring and as more disadvantage they offer. The faster deceleration of the more light wingloaded plane is the reason for a more tight turn while a turn with a constant G load.

Imho in Ah the inertia isnt modeled always right, but it got better with the last patches!  Heavy planes mainly suffer by their weight, while the advantage of the inertia dont count much.
For example the A6M´s keep energy at highspeed(+300mph IAS) like mad, while this relative big but light and powerless planes should bleed speed like mad, same count for the Hurri II.  At highspeed planes like the P47 and FW190 should very easy get rid of this lightweights by flying a highspeed smooth turn, where the high inertia and power keep should keep the speed much better up. Unfortunately its the other way around. Even the smalest turn slow the FW190 down, like dont have any weight, as result it only can run strait to gain distance, a upzoom at 350mph in low level with 2k distance is suecide(and that vs so outdated planes like the Zero and HurriII). While a upzoom with initially 400mph a Spit16 close in to the FW190A8 from 3k distance, althought the the Spit was intially more slow. Looks like the inertia of 850kg at 400mph dont count much, while the P51D and even the FW190A5 zoom pretty good or at least better at 400mph.  

Greetings,
« Last Edit: November 17, 2006, 02:51:39 PM by Knegel »

Offline hitech

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« Reply #46 on: November 17, 2006, 03:12:36 PM »
Knegel:
Quote

Imho in Ah the inertia isnt modeled always right, but it got better with the last patches! Heavy planes mainly suffer by their weight, while the advantage of the inertia dont count much.
For example the A6M´s keep energy at highspeed(+300mph IAS) like mad, while this relative big but light and powerless planes should bleed speed like mad, same count for the Hurri II. At highspeed planes like the P47 and FW190 should very easy get rid of this lightweights by flying a highspeed smooth turn


What you are missing is it takes much more lift & hence more drag to turn a heavy wing load plane at the same g load. Therefore for a given G load and speed the heavy plane will be expending more kinetic energy (yes it also has more to spend), than the light wing loaded plane (which has less to spend).

And it is impossible for inertia (i.e. simply the mass of the airplane) to be wrong in AH.

Offline Knegel

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« Reply #47 on: November 18, 2006, 01:10:20 AM »
Quote
Originally posted by hitech
Knegel:


What you are missing is it takes much more lift & hence more drag to turn a heavy wing load plane at the same g load. Therefore for a given G load and speed the heavy plane will be expending more kinetic energy (yes it also has more to spend), than the light wing loaded plane (which has less to spend).

And it is impossible for inertia (i.e. simply the mass of the airplane) to be wrong in AH.


Hi,

thats wrong!!!

A more heavy plane need more lift to turn at given G, a more heavy wingloaded plane can be more light and would need less lift to turn at given G.
Therefor the more heavy wingloaded plane dont will expending more kinetic energy, but the more heavy plane will do, but this is in relation to its wings(lift) and therefor isnt a handycap while a decelerated turn.

Thats why i took the SpitVb and 109F4 as eaxample, they are both similar heavy and also had similar power(combat power). Both planes need a similar lift to gain a given G. Afaik both wings did produce a very similar ammount of lift at max AoA, with a smal advantage for the big Spit wing, for the price of a high induced drag + high zero drag. As result the SpitV did decelerate faster, resulting in a more tight turn, particular for the price of Speed.

The main handycap of a heavy liftloaded plane is the limited turnradius until a speed where the blackout limit the turn, a higher stall speed and as result also a not that good sustained turn, regarding the E-bleed at highspeed its not not necessarily handycapped, this depends much more to the spanload AND specialy power. 1800HP in the 190A8 + the inertia out of 1400kg vs 1130HP of the A6M5 in low level should do the job while a upzoom out of 350mph.

Ok, if the inertia(somewhat thrust out of moving mass) cant be wrong, its to much induced drag, maybe the calculation dont take the influence of the wing aspect ratio into account??

The Japanese HQ also did need quiet a time to get aware that low wingload(liftload) isnt a advantage at highspeed and specialy hinder the planes to get to highspeed and to keep it.

Btw, i think the relation betwen F4U, P51D and A6M5 is good(only the US flaps are strange), but the P47(it miss the super flaps) and FW190 dont fit. Once the AH P51 also was such a energy killer.  

Greetings,

Offline Knegel

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« Reply #48 on: November 18, 2006, 01:18:20 AM »
Quote
Originally posted by Knegel
Hi,

thats wrong!!!

A more heavy plane need more lift to turn at given G, a more heavy wingloaded plane can be more light and would need less lift to turn at given G.
Therefor the more heavy wingloaded plane dont will expending more kinetic energy, but the more heavy plane will do, but this is in relation to its wings(lift) and therefor isnt a handycap while a decelerated turn.

Thats why i took the SpitVb and 109F4 as eaxample, they are both similar heavy and also had similar power(combat power). Both planes need a similar lift to gain a given G. Afaik both wings did produce a very similar ammount of lift at max AoA, with a smal advantage for the big Spit wing, for the price of a high induced drag + high zero drag. As result the SpitV did decelerate faster, resulting in a more tight turn, particular for the price of Speed.

The main handycap of a heavy liftloaded plane is the limited turnradius until a speed where the blackout limit the turn, a higher stall speed and as result also a not that good sustained turn, regarding the E-bleed at highspeed its not not necessarily handycapped, this depends much more to the spanload AND specialy power. 1800HP in the 190A8 + the inertia out of 1400kg vs 1130HP of the A6M5 in low level should do the job while a upzoom out of 350mph.

Ok, if the inertia(somewhat thrust out of moving mass) cant be wrong, its to much induced drag, maybe the calculation dont take the influence of the wing aspect ratio into account?? Or maybe the FW and P47 have to few drag and also to few power at highspeed, resulting in missing power to keep speed while turning?? Sooooo many possibilitys. ;)

The Japanese HQ also did need quiet a time to get aware that low wingload(liftload) isnt a advantage at highspeed and specialy hinder the planes to get to highspeed and to keep it.

Btw, i think the relation betwen F4U, P51D and A6M5 is good(only the US flaps are strange), but the P47(it miss the super flaps) and FW190 dont fit. Once the AH P51 also was such a energy killer.  

Greetings,

Offline Charge

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« Reply #49 on: November 18, 2006, 03:59:13 AM »
"Thats why i took the SpitVb and 109F4 as eaxample, they are both similar heavy and also had similar power(combat power). Both planes need a similar lift to gain a given G. Afaik both wings did produce a very similar ammount of lift at max AoA, with a smal advantage for the big Spit wing, for the price of a high induced drag + high zero drag. As result the SpitV did decelerate faster, resulting in a more tight turn, particular for the price of Speed."

While I agree with the general idea that these two planes area a close match I have yet to see a thorough analysis of their true relative turn perfomance. The 109 uses the slats to extend its max allowable AoA while at max allowable AoA only the wing tips of the Spit provide lift and the root section is a huge drag. I have always thought that since the basic airfoil the Spit has rather limited AoA the proble of Spit is that it cannot effectively decelerate where as the 109 can, and have to if it wishes to create lift to compete with a larger wing. Dunno...

On topic: Due to the big propellor and huge HP the Corsair is probably able to energize the lift of its wing's root section in slow flight -and that is why it is so prone to spin with torque. Due to this same factor I'd expect its departure to be very sudden and uncontrollable in a slow stall fight. Also remember that the lift the flaps produce is not free but comes with a drag penalty. Notice that the full flaps extend to 50 deg and with max AoA the flap angle to airflow is somewhere around 65 deg. The effect of gull wing is stabilizing but I doubt it produces any magical qualities (like the elliptic wing) but it hides the actual wingspan the wing has.



-C+
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Offline Squire

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« Reply #50 on: November 18, 2006, 09:28:52 AM »
The design of the Spitfire wing was such that when the stall occured, the stall happened 1st at the wingtips, to give the pilot some warning, and it made the stall more gentle.

Source-

"A feature of the final Spitfire design that has often been singled out by pilots is its washout feature, which was unusual at the time. The incidence of the wing is +2° at its root and −½° at its tip. This twist means that the wing roots will stall before the tips, reducing the potentially dangerous rolling moment in the stall known as a spin.

Many pilots have benefited from this feature in combat when doing tight turns close to the aircraft's limits, because when the wing root stalled it made the control column shake, giving the pilot a warning that he was about to reach the limit of the aircraft's performance."

...Im not sure what to make of some of the other comments, Spit not being able to decelerate ect, I really have no idea what you guys are talking about there.

...A low wing loading means you decelerate more slowly at the same G as an a/c with a higher wing loading, ie. it retains energy more efficiently, thats how a/c out turn each other, by retaining better E. At a certain point the high wing loading a/c has to drop to a gentler G, or stall out.

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Offline Charge

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« Reply #51 on: November 18, 2006, 11:17:56 AM »
No biggie, but a slight correction:

"The design of the Spitfire wing was such that when the stall occured, the stall happened 1st at the wingtips, to give the pilot some warning, and it made the stall more gentle."

"This twist means that the wing roots will stall before the tips"

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Offline Knegel

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« Reply #52 on: November 18, 2006, 01:05:40 PM »
Quote
Originally posted by Charge
[B
While I agree with the general idea that these two planes area a close match I have yet to see a thorough analysis of their true relative turn perfomance. The 109 uses the slats to extend its max allowable AoA while at max allowable AoA only the wing tips of the Spit provide lift and the root section is a huge drag. I have always thought that since the basic airfoil the Spit has rather limited AoA the proble of Spit is that it cannot effectively decelerate where as the 109 can, and have to if it wishes to create lift to compete with a larger wing. Dunno...

On topic: Due to the big propellor and huge HP the Corsair is probably able to energize the lift of its wing's root section in slow flight -and that is why it is so prone to spin with torque. Due to this same factor I'd expect its departure to be very sudden and uncontrollable in a slow stall fight. Also remember that the lift the flaps produce is not free but comes with a drag penalty. Notice that the full flaps extend to 50 deg and with max AoA the flap angle to airflow is somewhere around 65 deg. The effect of gull wing is stabilizing but I doubt it produces any magical qualities (like the elliptic wing) but it hides the actual wingspan the wing has.



-C+ [/B]


Hi,

if you wanna get a idea of the lift relation with max AoA, simply compare the stallspeeds. Regarding this the Spit and 109 was pretty close.

The flat airfoil and probably also the "twisted" wing and also the smal wing aspect ratio of the Spit are ptobably the reason for its smal lift factor, which lead to a unexpected "bad" liftload in relation to its wingload.

How much drag the open slats of the 109 did produce we only can guess, same like the we only can guess what induced drag the stalled part of the Spitwing did produce.

But anyway, i dont was up to start a Spit/109 discussion, i only was up to try to explain that a high wingload isnt a indicator for a high e-bleed!

In generally its not good for any plane to make hard manouvers with full flaps, cause extracted flaps decrease the aspectratio and make the planes more unstable. In general flaps was made to drop the nose and to reduce speed(drag). The max AoA normaly also get minimized with full flaps, as result of all this the turn performence of a plane with full flaps decrease. Flying with a high bank angle at slow speed lead to extreme altitude losts, but this i cant see regarding the AH F4U.

The AH F4U can extract the flaps at very high speed(in relation to most other AH planes) and it still keep energy like mad. The Spit flaps are same strange. To use the flaps in the SpitV is a real bringer, while the real flaps was mainly made to create drag and to lower the nose(the spit only had full flaps or nothing).

Greetings,

Knegel

Offline bozon

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« Reply #53 on: November 18, 2006, 05:03:12 PM »
Twisting the wing reduces its efficiency in significant parts of the envelope. What it does allow are two main things:
1. It allows the stall to develop progressively giving the pilot ample warning.
2. It reduces AoA at the aileron section. This is extremely important at high AoA as deflecting the aileron may push the wing beyond the stall on one wing (the one that is supposed to go up in the roll). When only one wing stalls, the plane flips over instantly. So when stall fighting, an attempt to roll hard right may result in a snap roll to the left. The twist of the wing delays this effect - at the cost of efficiency, mainly in high speeds.
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Offline gripen

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« Reply #54 on: November 19, 2006, 02:28:32 AM »
The wing twist or the slots/slats were generally just solutions to the same tip stalling problem in the WWII fighters. Both solutions have good and bad points; at low AoA twist causes some additional (form and induced) drag while the slots/slats also ad some drag (even if closed).

gripen

Offline hitech

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« Reply #55 on: November 19, 2006, 08:46:33 AM »
Knegel: Not really Disagreeing with you that much. But notice in the piece of your post I disagreed with, you were refereeing to inertia. I.E. heavier plane.

In my posted case, I was analyzing same wing & area different plane weights.


HiTech

Offline Hawco

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« Reply #56 on: November 19, 2006, 11:26:23 AM »
So the bottom line is that if you play your cards right while flying the 1A, there's a good chance you'll get inside a Spit 16 or an lgay while turning?
If this is true then that has made my day!:aok
Only downside to that is more than likely you will die quickly after as you would be a sitting duck, worth it though isn't it?

Offline stantond

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« Reply #57 on: November 19, 2006, 08:05:02 PM »
Of the american planes, the F4U series does have more low speed maneuverability and can fly at 110 ias, but a spit 16 will make a sustained turn faster than the F4U at nearly the same speed.  Turn radius is one parameter, like the size of a womans foot.  It doesn't say much about acceleration performance, turn rate, roll rate, or control response for an airplane.    Not that it's bad data, it's just not so useful by itself.

One idea I started on, but didn't get too far, was constructing energy-maneuverability graphs for the AH plane set.  I figured out how to make them, and I think there's some web resources describing them as well.  A concerted (or just group) effort to collect data for E-M charts would go a long way to explaining aircraft relative performance.  E-M charts are a concept thought up after the jet age and so there's no real WW2 historical charts of that type.  

Badboy has described at various times how a p51 can out turn a spitfire by using E-M diagrams.  The same can be said for F4U's vs spits, La's, or even Hurricanes.  The general notion is to exploit the strengths of the aircraft you are in and not the aircraft you are fighting.

Shaw talks about them as turn rate versus speed diagrams with velocity (Energy) on the x-axis and turn rate (maneuverability) on the y-axis for a series of g-load curves (on pg 391).  The maximum instantaneous turn rate can be easily found from this type of curve set at the 5g (or 6g) load speed.  Of course, that type of diagram is good for only one set of conditions including flap settings.  However, depending upon the variations in the curves they can be generalized over a range of altitudes, fuel loads, and flap settings.  

So, my point is that while minimum turn radius data point is a good start, it is only near the minimum speed.  That speed is generally much  less than the maximum turn rate speed.  While I apprecate the data for turn radius, turn rate data at various g's is more useful for an energy-maneuverabilty diagram.  




Regards,

Malta

Offline F4UDOA

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« Reply #58 on: November 19, 2006, 10:41:12 PM »
Malta,

EM charts are great but they are typically made at no power or idle power and no flaps.

The addition of power changes things but at least you get a baseline idea of what the maneuvering envelope should be. In reality these aircraft could pull pretty high instantanious G's at low speeds than in AH but I think people would feel like it was gamey if it were modeled that way.

I have a few EM diagrams if your interested.

Offline stantond

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« Reply #59 on: November 19, 2006, 10:49:46 PM »
Actually, the ones I've seen have been made at WEP power.  Mil power adds yet another change to the curves.  It has to do with a small change in specific power.  Nothing like a jet engine in afterburner, but there is a difference.

Sure, I'm always interested in more performance information but I've never heard they were made at idle before.  Maybe we aren't talking about the same thing?

Here is a thread describing the E-M diagrams:
http://www.hitechcreations.com/forums/showthread.php?threadid=164617&referrerid=4629


Regards,

Malta
« Last Edit: November 19, 2006, 11:00:10 PM by stantond »