F6F Hellcat

[Saxman]

Looks to me like the most critical stall speed in a fight, power on flaps down, is right where it should be. Power off flaps down may be wrong, but who's honestly flying around with power off in combat?

[Baumer]

I know several of the top sticks are very adept at the flaps down power off turn as part of a good rolling scissors, not that they use it all the time. And a 10% error is pretty significant when your in a tight stall fight.

[mechanic]

power off (0% throttle, not engine off) is the only way to dump speed quickly, otherwise you are still pulling yourself through the air

[TequilaChaser]

The fact that the Corsair in game stalls below every documented stall speed is proof enough that something is wrong.

What ever is wrong probably applies to all aircraft, not just the Corsair.

FLS I just re-ran my stall stall tests for the F4U-1D and this is what I came up with. All stalls were initiated at 500 feet with stabilized speed and maintaining close to zero vertical speed as the plane decelerated. Also, per Hitech I chose to record a stall as the onset of canopy frame shake, this is not when the plane is truly stalled but at least 1 of the lift points in the aerodynamic model is stalled. Typically a pilot would have to fly deeper into a stall to even notice it, most planes I've flown the stall speed in the POH is when the nose drops. I ran these tests at 11,465lbs take off weight with fuel burn at 1.00.

per the Corsair POH 15 Mar 45 with an aircraft weight of 11,300 lbs.

Gear up, flaps up, throttle closed, stall speed of 87kts (100mph)- my ten test average- 98.2 mph
Gear down, flaps down (50), throttle closed, stall speed of 75kts (86mph)- my ten test average- 73.5 mph
Gear up, flaps up, power on (18" & 2400 rpm) stall speed of 84kts (96mph)- my ten test average- 96.8 mph
Gear down, flaps down (50), power on (23" & 2400 rpm) stall speed of 66kts (75mph)- my ten test average- 75.5 mph

The Corsair is my favorite aircraft, but I choose not to fly it much in Aces High. It's excessive views and unrealistic low speed modeling make it too inaccurate for me.

Back  a while when either hitech or pyro posted that one image of all the different data gathering points along the wing of either the F4U or might of been the F6f, Brooke went and did some very thorough data testing...... comparing Aces high planes F4U-1  and the P38J  comparing their flight characteristics / stall points to what the Real Life POH ( Pilots Operational Handbook ) data showed for these particular plane types......  Brooke's research showed that for just about 99.9% ( <--- my thought ) of the data being compared, that the numbers were nearly identical from Real Life to Aces High, acknowledging that their was a .5 mph  to 1 mph  difference here and there........ with maybe 1 or 2 of the test having a lil bit higher indifference of around 2 mph or so.....

here is a link to that data research, that Brooke did:
http://www.electraforge.com/brooke/flightsims/aces_high/stallSpeedMath/stallSpeedMath.html

in regards to using flaps down ( is this full flaps??? ) and power off while turning in a rolling scissors,  I  have to disagree with the thought of anyone doing this..... one should not be chopping throttle/throttle off in a rolling scissors battle, and one should avoid as much as possible using flaps, especially full flaps......... unless they are at the endgame / stallmate in such a rolling scissors that they have no options left..... One should want to have maximum throttle / thrust available and use the Helix and the angle of the helix to prevail in the rolling scissors.....

I do think that it might be possible, and you Baumer, have stated it ( I think earlier )... that the slipstream might be causing some unforeseen adverse effect............ in return letting the F4U series have more rudder authority than they might should have................ maybe because the F4U has gullwings and since they angle down then back up, they do not break up the airflow in such away as to negate rudder authority ability, like what ,might happen to the slipstream forces on say the F6f, or P51, or P38.......... since these planes do not have that particular wing design, by effect these planes wings break up or dirty up the slip stream airflow to where it is negligible and the slipstream airflow is of no benefit..... yet on the F4U and the bent wings, it works in such a way that the F4U does benefit......

the one constant that must be realized is ........ no one back then was able to severely push a plane beyond its boundaries too far, without consequence of them losing their lives......
so if HTC/ hitech can get so close if not exact in plane scaling, powerplant performace, lift-drag-thrust-gravity etc.... , stall performance, turn and climb and speed performance...... is it not possible to say that HTC has been able to get as close to possible to the real thing and that because people have 10's of thousands of hours over the years with no worries of actually dieing, that some of the things that have been seen in game from some of the aircraft, might indeed be possible? after all?


I will close with, I seriously think, if something was so far askew-ed and out of whack with the F4U flight model or flaps, for such a long time as all the different posts in the different AH forums / sub forums show from the complaint threads that have popped up from time to time over the years...... that if something actually was wrong, HiTech would have done fixed it ..... and would have posted that they found an error or something....... they do do that when they find something out of place or find anything that is off

now, you done posted and have been talking with him, regarding a possible torque & slipstream issue.....  and it could very well have some merit to it, and if it does, I would think that HiTech/ HTC would positively fix it and post about it in the update notes,  when an update or newer patch or version comes out..... Maybe the F4U does gain a benefit to be able to have good rudder authority when the indicator is reading 30 mph IAS,  due to its gull wing design and having a larger unobstructed opening for slipstream air to pass through rather than like the other planes who's wings would break it up / dirty it up more ( <--- just an uneducated theory )

<S>

TC

[Saxman]

I think TC's got an interesting point on the gull wings.

Here's a simple front-plan view of the F6F:



By comparison, the F4U:



The wing configuration definitely drops the Corsair's wing well below the center of the prop. Could this have anything to do with how the slipstream modeling affects the Corsair?

[F4UDOA]

Well, I suppose that depends on how you interpret this text:

"Accurate data on minimum turn radius of fighter types is difficult to come by or to estimate.  Information is available, however, from one of the World War II U.S. fighter conferences on stall speeds in three g turns for eight of the eleven types considered here.  Data are provided for the P-38, P-47, P-51, P-61, P-63, FM-2, F4U-1D, and F6F-5.  The information is for clean aircraft configuration, that is gear and flaps retracted, canopy closed, and no external stores aboard.  The assumption is made in each case that engine power available is sufficient to keep the plane in level flight (not sinking) during the turn.  In such a case the minimum turn radius occurs when the wing develops the maximum possible lift coefficient without stalling.  The actual minimum turn radii are not calculated, but Table 103 (quoted in one of my earlier posts) shows the eight types ranked in order from best to poorest turn radius capibility.  The radius depends on the airplane wing loading (weight divided by wing area) and maximum wing lift co-efficient.  A low wing loading tends to make the plane more maneuverable, that is, to have a tighter turning circle capability;  if the wing loading is high turning is penalized.  On the other hand if the wing maximum lift coefficient is low the turn capability is poor;  if it is high turning can be tighter;  the proportionality is inverse."

Shuckins,

I say this because I actually met with Mr.Dean before he passed about 10 + years ago at his home in Concord Pa.not far from me.I asked him about this. His data came from different sources which is why it happens to be scattered. If you calculate the Clmax of the F4U from the stall speeds in the flight manual circa F4U-1D 1946 you will get 1.47/48. The 1.2 comes from a NACA document from an early test airframe from NACA doc 728 that can be found online. You can check the Clmax against any of the aircraft in that table and many are unusual (as I remember). the first F4U's had many imperfections in the wings that lowered the Clmax. I'll pull up some of my old docs if you want.



_____________________________

The part that is bolded indicates that Francis Dean did not come up with this data on his own, or make it up.  Since the men who compiled the data were the flight engineers and military pilots who attended the fighter conference one MUST assume that they knew what they were talking about.  The text that comes after the bolded part stems from Dean attempting to make clear how the data was compiled and why certain assumptions were made.

[Karnak]

From the AH v2.27 patch notes:

Changed the cockpit head bounds on the F6F.

[MAINER]

From the AH v2.27 patch notes:

 

[Shuckins]

F4UDOA, thanks for the reply and the offer.  I certainly would like to see your documents. 

[Shuckins]

In the fall of 1944 a captured Zero 52 was delivered to the NAS at Patuxent River, Maryland to be evaluated against the three main U.S. Naval fighters then employed in combat in the Pacific:  the F4U-1D, F6F-5, and the FM-2.  The results of those tests were released in the Air Command Weekly Intelligence Summary, Allied Technical Air Intelligence Unit, South East Asia, "Flight Trials of Zeke 52, December 17, 1944.

The data released in that summary make fascinating reading, not just because of the comparisons drawn with U.S. naval fighters but also in the unintended comparison drawn between the naval fighters as well.  The following data is taken from that summary.  For the purposes of the flight tests both aircraft were flown side by side, making all things equal in the beginning.  

"In a race for altitude, the best climb of the F4U-1D was equal to the Zero's up to 10,000ft, about 750fpm better at 18,000ft and about 500fpm better at 22,000ft and above.  Best climb speeds of the Corsair and Zero were 156mph and 122mph IAS respectively.

The F4U-1D was faster than the Zero 52 at all altitudes, having the least margin of 42mph at 5,000ft and the widest difference of 80mph at 25,000ft.  Top speeds attained were 413mph TAS at 20,400ft for the Corsair and 335mph TAS at 18,000ft for the Zero.

In slow speed turns the Zero could gain one turn in three and a half at 10,000ft.  At speeds around 202mph, however, by using flaps the F4U could stay with the Zero for about one-half turn, or until its speed fell off to 173mph.

The Zero climbed about 600fpm better than the F6F up to 9,000ft, after which the advantage fell off gradually until the two aircraft were about equal at 14,000ft.  Above this altitude the Hellcat had the advantage, varying from 500fpm better at 22,000ft, to about 250fpm better at 30,000ft.  Best climb speeds of the F6F-5 amd Zero 52 were 150mph and 122mph respectively.

The F6F-5 was faster than the Zero 52 at all altitudes, having the least margin of 25mph at 5,000ft and the widest difference of 75mph at 25,000ft.  Top speeds attained were 409mph at 21,600ft for the Hellcat, and 335mph at 18,000ft for the Zero.

Comments on turns for the Hellcat were identical to those made on the Corsair, except the attempts at turning with flaps were not mentioned.
________________________

Computer just started getting screwy on me....couldn't bold the top speed of the Hellcat.  However, the test indicated that the top speeds for bot the Corsair and Hellcat came at almost identical altitudes and were within 4mph of each other. 

According to Corkey Meyer, who test flew both aircraft, the reason the Corsair was 20 knots faster than the Hellcat at low altitudes was because its engine and carburetor were provided with ram air coming in to the main stage blower directly from the forward-facing wing duct, whereas the Hellcat had the carburetor air coming in from the accessory compartment of the fuselage just behind the engine, with no ram air effect.  The Hellcat was getting carburetor air at the same pressure as it would have were it motionless on the ground, and the Corsair was getting carburetor air supercharged by the speed of the airplane giving it more power and speed in the main stage blower.  In both aircraft, however, the designs were similar in that they provided ram air to the low and high blower stages.  Grumman's engineers had adopted the system used in the Hellcat because taking the warmer air for the main stage blower would prevent inadvertent carburetor icing engine failures.  The Wildcat had ram air in the main stage like the Corsair and many were lost because pilots failed to take precautions in time to avert this type of disaster.
____________________

I'm tired and gotta get up early to go to work.  More later.

[SectorNine50]

I'm confused.  Why would ram air matter on a turbo or supercharged engine?  Wouldn't the ram effect be basically negated by the compressor?

[Greebo]

No, the ram air pressure is added on to the supercharger(s) pressure and atmospheric pressure for that matter. So the pressure delivered to the engine is higher using ram air. Effectively using ram air gives you an extra supercharger stage for nothing.

[Gooss]

AKRaven flies the F6F very well. I'm usually in an F4U and he beats me like a drum.  I'm still a sucker for his "go vert-rudder kick-kill Gooss" move.  I avoid Greebo.

Any comment on the new head positions in the Hellcat making visibility better?

Regarding the F4U stall speeds, who cares?  An F4U at stall speed is a target.  I know this from experience.  It saves me a long flight rtb.

Too many hog pilots have resulted in more people learning how to kill them.  I wish for a limit to b-n-z passes.

HONK!
Gooss

[Slade]

>> Any comment on the new head positions in the Hellcat making visibility better?

It is such a micro change it is hard to call it an "improvement".

There are some internet sources (who is to say which is correct?) that claim all around visibility in the F6 was better than the F4-U.  It would be nice if the F6 rear view was a good as the F4-U. 

There is an F6 at Bradly Field in Windsor Locks, CT.  I am tempted to call them up and ask them to get in it with a digital camera and take a picture of the rear view.  Then pass that on to AH.

[Slade]

>> Any comment on the new head positions in the Hellcat making visibility better?

It is such a micro change it is hard to call it an "improvement".

There are some internet sources (who is to say which is correct?) that claim all around visibility in the F6 was better than the F4-U.  It would be nice if the F6 rear view was a good as the F4-U. 

There is an F6 at Bradly Field in Windsor Locks, CT.  I am tempted to call them up and ask them to get in it with a digital camera and take a picture of the rear view.  Then pass that on to AH.