F4U turn performance, flaps, the real plane, etc (discussion)

[mtnman]

Obviously, or I would not have said anything.

Makes for easy kills for you then, eh?

[nrshida]

Chalenge read my last post and decided he needed to extend away and gain some more energy before re-engaging.

[Chalenge]

Chalenge read my last post and decided he needed to extend away and gain some more energy before re-engaging.

No. I read your post and decided you are still a noob. People created the term 'pick' for the reasons I described. Most of them come form the DA and bring the DA mentality to the war arena thinking everyone will agree with them. They have taken over the General Forum and anyone posting anything contrary to their DA views are immediately attacked in an attempt to silence and different views.

When you grow up and finally molt out of the DA mentality you may discover that the game has many different aspects and all of them can be fun. But it's your money to toss away to mindless-endless furballing if you want. I cannot see the logic in repeated long trips ending in death but if that's your cup of tea why would I even try to stop you?

Some people never do change because they do not care to learn. I think that's you.

[nrshida]

Let's take this elsewhere and leave this thread to the discussion of flaps shall we:-

http://bbs.hitechcreations.com/smf/index.php/topic,344342.0.html

[mtnman]

I would be grateful if someone with a deep technical understanding of aircraft dynamics could explain this because I thought I understood that Fowler flaps increased the turn rate and given they are reasonably large on the Ki-84 I'm rather sceptical about the comparable rates. How can the DPS be the same with a good deal more lifting surface available, longer chord, a better camber and a slightly higher thrust to drag ratio?

Also I can only assume with the Corsair that the flaps alter the camber to a very favourable degree since apparently the plain flap is one of the less efficient solutions (not the worst). Or is it to do with the speed combinations of deployment which are rather high? This is what I found interesting about the Whirlwind, that the flap could be deployed at so high a speed, around or just below instantaneous corner speed if memory serves.

Sorry for the minor hijack, but any opportunity to learn...

I don't know that this is a hijack?  I think it's an applicable topic for this discussion.

I would also like to have someone with a deeper knowledge step in.  Personally, I've always wondered what the aerodynamic effect of the F4U flaps is compared to flaps on more conventional wings...

If you look at this image, it's easy to see that fully 1/3 of the F4U flaps are deflecting the air in a totally different manner than would happen on conventional wings.  What is the effect of this?  Is it helpful, or detrimental?



On a conventional wing, in a bank all of the deflected air from the flaps on the "high side" of the turn is being pushed to the outside of the turn, and is doing little to provide lift for the plane.  At the same time, the flaps on the lower wing are providing more lift, but holding the plane in this bank with aileron and/or rudder is essentially "fighting" this flap.

On the F4U though, the 1/3 of the flap surface on the high side of the bank is still deflecting air much more directly downward (providing more effective lift).  This is also helping to hold the high wing high, and possibly requiring less aileron/rudder deflection to hold the bank?  Pure speculation here, I honestly don't know...

In level flight with flaps deflected, do the inner flap surfaces on the F4U create a higher pressure under the plane?  Like a "bubble" effect, for lack of a better description?  If so, is this helpful or detrimental?  Does it compare in the slightest to ground effect?  Does it add stability, or detract from it?

Real world, I wouldn't expect these effects (if they exist) to be remarked upon, for many of the same reasons I outlined many posts ago.  I suspect it would take wind tunnel testing to prove or disprove these theories, and I've never come across any describing it?  Real world, I don't recall seeing anything that mentions flap causing stability problems in the F4U?  While landing mishaps were an issue, they seem to be more of a throttle management issue?

Since you brought up the KI84, I took a shot of that too to show how I believe the air is deflected differently.



Please ignore the actual bank angles shown in these images- they are just clips from films so are not comparable.

In testing, has anyone checked what the bank angle is for the different planes at the edge of stall?  I.e. is the F4U capable of holding a more severe bank in a minimum-radius edge-of-stall circle than a P51, or KI84, or whatever?  Is this relevant?  Correct?

[FLS]

 How can the DPS be the same with a good deal more lifting surface available, longer chord, a better camber and a slightly higher thrust to drag ratio?

Where does the higher thrust to drag come from? Thrust is fixed and drag is increased.

The DPS can be the same because the wing is moving slower and that limits the load factor. Turn rate is both speed and load factor.

[Saxman]

mtn,

I've always wondered this myself. It's already known that the configuration of the Corsair's wing had an effect on drag reduction, but no one's ever seemed to been able to answer whether it could affect the flaps as well.

[Chalenge]

Let's take this elsewhere and leave this thread to the discussion of flaps shall we:-

http://bbs.hitechcreations.com/smf/index.php/topic,344342.0.html

You are the one that jumped in and started mouthing off. Just leave.

[Chalenge]

If you look at this image, it's easy to see that fully 1/3 of the F4U flaps are deflecting the air in a totally different manner than would happen on conventional wings.  What is the effect of this?  Is it helpful, or detrimental?

I don't think the flow is actually as you indicated. The relative wind is still the relative wind. I have heard also that the gull wing design prevented the blanketing of the tail during nose high slow flight conditions, but during sustained low-speed flight (especially in disturbed airflow from another aircraft - not occurring in AH) I am not sure if that the case, especially with more than two notches of flaps. My problem with the flap fights has always been that the people that do that sort of thing can even use full flaps. I don't believe that is relative to any reality. The problem being, as someone else pointed out (Badboy I think) that the nose rate has actually dropped below what would be the optimum with only two notches. So dropping flaps should be detrimental to angle fighting, but it seems to be everyones passion.

My entire point being (the problem I see in it) is that your entire idea of flap fighting is to get out of the way of attackers and yet you are not flying in an optimal manner at all. The reward of course is that once you finally get killed you can laugh and claim you had all of your flaps out for so long and no one got you, but you're still dead. Admitting to it. . . your call.

[bozon]

mtnman, the wind does not flow as you pictured it, nor it is "deflected" at all. The flaps change the profile of the wing (lets call it more "curved") and increase the flow vortex at the trailing edge. The result is that the flow accelerates more above the wing (or sucked from above into the vortex if you want to imagine it that way) and lift is increased. Drag also increased because a lot more energy goes to fuel the increased vortex and turbulence at the trailing edge.

[FLS]

In testing, has anyone checked what the bank angle is for the different planes at the edge of stall?  I.e. is the F4U capable of holding a more severe bank in a minimum-radius edge-of-stall circle than a P51, or KI84, or whatever?  Is this relevant?  Correct?

The lift vector is always "up". Bank angle is proportional to load factor.

[nrshida]

You are the one that jumped in and started mouthing off. Just leave.

Funny, the sequence of posts suggest other.

Since you said the Corsair's flaps were not such a great benefit you have demonstrated a lack of understanding of the topic and it's further been established from your score and comments from other players that you are a picker and a runner so you are far less qualified to discuss flaps than me. Why don't you leave.

[nrshida]

Where does the higher thrust to drag come from? Thrust is fixed and drag is increased.

I gathered from other discussions that the efficiency of the prop increased as the airspeed decreased, also parasitic drag dropped off to a negligible level and lift induced drag was to do primarily with Alpha and G load. Have I understood those aspects incorrectly? I do not know the proportions of those even if I have, hence the discussion.

The DPS can be the same because the wing is moving slower and that limits the load factor. Turn rate is both speed and load factor.

Right, but the lifting area is also increased with Fowler flaps, say, so in the case of the Ki-84 that increase in lift merely supplies for reduced airspeed but with the Corsair (with the same lifting area regardless of flap position) it somehow increases it's DPS? Can you explain that to me please?


It's an interesting theory Mtnman, but wouldn't the 'angled' downwards force from the right side be cancelled out by that from the left side?

[nrshida]

In testing, has anyone checked what the bank angle is for the different planes at the edge of stall?  I.e. is the F4U capable of holding a more severe bank in a minimum-radius edge-of-stall circle than a P51, or KI84, or whatever?  Is this relevant?  Correct?

Photoshop says 66 degrees. Co-ordinated turn, 25% fuel, full ammo, full flaps, 15.5 seconds 360 flat turn 23.2 D/Sec.

[FLS]

I gathered from other discussions that the efficiency of the prop increased as the airspeed decreased, also parasitic drag dropped off to a negligible level and lift induced drag was to do primarily with Alpha and G load. Have I understood those aspects incorrectly? I do not know the proportions of those even if I have, hence the discussion.

When you add flaps you add drag. If lift to drag improved why would you ever have your flaps up?

Right, but the lifting area is also increased with Fowler flaps, say, so in the case of the Ki-84 that increase in lift merely supplies for reduced airspeed but with the Corsair (with the same lifting area regardless of flap position) it somehow increases it's DPS? Can you explain that to me please?

You're just looking at the difference between full flaps and none.  Fowler flaps can be relatively low drag but likely not after extending more than 50%.  Full flaps are designed for landing slowly, their effect on turn rate is secondary.