Acceleration comparisons

[JtD]

Regarding trim, both the F4U and the F6F as tested by NACA required loads of elevator trim. Stick force changes were in the range of 30lb between 200 and 400 mph in level flight. Trimmed for neutral stick forces at low speed, pilots would sometimes not be able to keep the aircraft in a dive.
Trim as suchs seems to have been a bit more effective than it is in game.

[MaxGunz]

Is giving it full throttle and RPM going to give the best acceleration especially to heavy planes with huge power?

Most prop speed controls will try and maintain prop RPM which at lower speeds may be course enough to stall the prop just keeping it from over-rev. Manual 100% RPM will waste full power but at least be a bit better than prop AOA too high. Either way is "spinning wheels" without smoke and noise to show it.

Getting the most out of a plane isn't 'simply' anything.

If you want accurate data, get a devicelink data logger like UDPSpeed and ditch the stopwatch.

[Luno13]

So, I guess what Horseback is getting at is that the USN aircraft require more trim to accelerate properly than their IJN counterparts, which is unfair/unrealistic

If anything, that has to be a problem with the IJN aircraft. Changing speed in an airplane requires a fair deal of attention to trim.

I can also imagine that part of the problem is the uber-experience of online pilots - thousands of hours of flight time with zero real deaths...Even if you run away properly they can nail you from 500+ meters (and a lot of pilots use zoom to do it from even further).

[horseback]

Originally Posted by Luno13

So, I guess what Horseback is getting at is that the USN aircraft require more trim to accelerate properly than their IJN counterparts, which is unfair/unrealistic

If anything, that has to be a problem with the IJN aircraft. Changing speed in an airplane requires a fair deal of attention to trim.

I can also imagine that part of the problem is the uber-experience of online pilots - thousands of hours of flight time with zero real deaths...Even if you run away properly they can nail you from 500+ meters (and a lot of pilots use zoom to do it from even further).

On the contrary, I am pointing out that it is much harder to make any kind of maneuver in the USN aircraft without lots of trim adjustments. You can easily straighten out and run away (and you will be rewarded by even more speed sooner if you drop your nose a bit), but if you attempt all but the most careful turns or climbs without your eyes glued to the slip ball, you will lose all of your hard won energy rather quickly.

The IJN/IJA fighters do require trim adjustments, but the adjustments are not excessive in terms of button presses and they are consistent and predictable in a way that the Corsair and Hellcat are not. This allows the fairly average IJN flyer a degree of immediate precision that the USN flyer must learn over many times more hours of practice (and if he's using button trim, he's still going to be 'behind the curve' the moment he wiggles his stick).

You can add in the way that the F4U and F6F's noses drop and later rise in level (changing AOA) flight as speed increases (this is also evident in the P-47); most of us use the gunsight or some part of the cockpit framing as a reference to maintain our angle of flight, and this will add to the problems of flying with any degree of precision, especially if competing against aircraft whose trim requirements and flight qualities are best guesses derived from 70 year old documents and pilot reports.

cheers

horseback

[horseback]

Originally Posted by MaxGunz

Is giving it full throttle and RPM going to give the best acceleration especially to heavy planes with huge power?

Most prop speed controls will try and maintain prop RPM which at lower speeds may be course enough to stall the prop just keeping it from over-rev. Manual 100% RPM will waste full power but at least be a bit better than prop AOA too high. Either way is "spinning wheels" without smoke and noise to show it.

Getting the most out of a plane isn't 'simply' anything.

If you want accurate data, get a devicelink data logger like UDPSpeed and ditch the stopwatch.

I'm trying to do this from the general player population's point of view; I expect that anyone using the same methods would be able to get very close to the same results that I do, which is the whole point. I don't use a stopwatch, just the track's time displayed in the lower right hand corner. The tool I use most by far is the 'Pause' key.

As for prop speed, for most cases I use the 100% prop pitch setting because it is loosely analogous to low gear in a car; unfortunately, when I try to get a fast start from first gear in a car, I can gauge how much power to apply by feel, something that is not available to the virtual pilot, so I felt that I had to keep things fairly basic. I tried a few experiments with the Spit IX and the P-51C with the engines at both 2700 and 3000 rpm, which are included in the Spitfirepalooza and USAAF fighters charts. The Spit at 3000rpm is superior to the Spit at 2700 at all speeds, while the Mustang at 3000 will rip past the Mustang at 2800 until they reach about 510 kph indicated, at which point the Pony flying at 2700 rpm passed and reached 530 IAS almost a minute sooner (looking at the data table, the 2700rpm bird actually seems to start gaining speed faster around the 490 kph point, which is where I would suggest 'changing gears' if you have to run away from trouble). The Spit IX and the P-51 have very similar if not exactly the same engines, so I figured it would be a good comparison to work with. I created a special chart demonstrating the differences which I will attach below.

I left the Germans' prop pitch, with their 'automatic transmissions', alone, but most of the other aircraft seemed to respond better to just pushing the prop pitch all the way forward at the same time you shove the throttle to the stops. In all cases, I make sure that the supercharger is in the right stage, the mixture setting is appropriate (for instance, the Soviet fighters all ran better at 80% mixture at 3050m than at 100%, while the CW-21B needed 120% mixture to keep even with the Zeke 21) and that the aircraft is trimmed for level flight at 270 kph IAS at around the suggested rpm for cruise (and that the engine is relatively cool).

If someone expert in one type or another feels that he can obtain better results with different settings in a given type, I invite them to put their oar in and help out the community at large.

cheers

horseback

[Jumoschwanz]

Originally Posted by horseback

If someone expert in one type or another feels that he can obtain better results with different settings in a given type, I invite them to put their oar in and help out the community at large.
[Horseback

I did acceleration testing of all the aircraft in this sim for many years, not to help the community at large, but to get an edge on them flying online. Sometimes I did post results here and there on various forums, but as Horseback found out, it is time consuming and my hard work was so I could shoot others down, if they were not smart enough or too lazy to do the work I did, then screw them.

The acceleration tests I did were done in a different way. I figured there were two different things to know about my aircraft and how it accelerated.

The first was acceleration at very low speed. Often if you get mixed up in a dogfight you might find yourself at stall speed, or almost stopped in some evasive maneuver. So I tested all aircraft to see what speed they could get to in a set distance, starting at zero.

Once I had the speeds all aircraft could reach in a set distance from zero, then I saw what speed they reached in exactly twice that distance, so then I knew which aircraft could get away from which from almost no speed at all, and I also knew which could gain the most speed when already starting at a high speed. Both very useful in evasive maneuvers and in energy fighting.

I also tested the top speeds of all aircraft both on the deck and at 5000 meters altitude, which was also very useful to know for every common aircraft flown online in popular servers.

Yes, some aircraft need different trimming and other settings to get the most out of them, but that is to be expected as they were different machines manufactured thousands of miles from each other by extremely different cultures and engineers.

That is why making all the aircraft behave exactly the same would be ridiculous whether it trim or any other parameter or control feature, if you do that we may as well get rid of all the aircraft in the sim except for one, we could all just fly 25lb spits.

I say plug the engineering data for each aircraft into the IL2 simulator and fly what you get. Every pilot in WWII had to learn his specific aircraft, if he switched to a different one then he was set back and had to learn many things all over again.

[horseback]

Originally Posted by Jumoschwanz

Yes, some aircraft need different trimming and other settings to get the most out of them, but that is to be expected as they were different machines manufactured thousands of miles from each other by extremely different cultures and engineers.

That is why making all the aircraft behave exactly the same would be ridiculous whether it trim or any other parameter or control feature, if you do that we may as well get rid of all the aircraft in the sim except for one, we could all just fly 25lb spits.

I say plug the engineering data for each aircraft into the IL2 simulator and fly what you get. Every pilot in WWII had to learn his specific aircraft, if he switched to a different one then he was set back and had to learn many things all over again.

Fine by me, but let's limit the engineering data to what was known and documented in 1945, instead of a steady diet of revised, new & improved data taken with newer and better measuring sticks for just the one group of (aging) aircraft. I spent a good sized chunk of my life testing refurbished and rebuilt weapons and fire control systems that date back to the 1960s; one of our ongoing problems was that modern testing and measurement methods are far more accurate than the ones used to establish the original performance parameters of these systems back in the day. We often had to demonstrate to the Government representative who had to sign off on the performance that these new testing systems left us a whole lot less 'wiggle room' than the ones devised during the Nixon Administration, and that we were still meeting and exceeding the original specifications that could be measured when the specs were written.

Excessive trim modeling is a very good way to keep a good aircraft's performance down in practice while still allowing it to achieve its accepted performance figures; the historical record says quite clearly that the Corsair, the Mustang, the P-47 and the Hellcat were 'easily trimmed', specifically in reference to the earlier US fighters like the Wildcat, P-39 and particularly the P-40, all of which enjoy relatively similar (and easy) trim models in the game compared to the other depicted fighters of WWII (as of version 4.11.1; time will tell if 4.12 is any better).

Of the later fighters, only the Hellcat needed 'much' trim adjustment, but it was considered easily done. That is obviously not my experience in this simulation. The Merlin Mustang from every contemporary account and description needed very little or no trim adjustment for minor changes in speed or throttle (the Allison Mustangs needed practically none at any speed), but the in-game version needs trim adjustment in elevator and rudder for every variation of 10kph (that's only 6 mph, fellow Yanks) in speed or 5% of throttle, which is considerably more than either of the two best known study simulations of the P-51 depict (and strangely enough, I found a quote from a pilot in America's Hundred Thousand that complains of exactly that sort of behavior in the P-40,only for speed variations of as little as 10 mph (or 16 kph), which tells me that the trim model would be overdone by at least 60% even if it were assigned to the universally acknowledged worst trimming American fighter of the war).

The real P-38 needed NO elevator (or rudder) trim for speed and throttle variations (per America’s Hundred Thousand), but the Il-2 Sturmovik Lightning will go literally straight up when you push the throttle forward without shoving the stick three quarters of the way forward at the same instant and punching the elevator trim button constantly for as long as the speed continues to increase. (and it's a lot slower than the real thing was)

The real life P-47 needed no elevator trim for initial acceleration, but the in-game version does the same thing as the Lightning, with the added entertainment value of needing a ton of right rudder as well, and like the Corsair, the nose tends to dip as speed increases in the level plane; by this I mean that the angle of attack varies significantly with speed, something I've never read or heard about in these aircraft in over 45 years of reading, modeling or personally talking to men who flew these aircraft (you'd think that somebody would have mentioned it...).

As for the Spitfire, I have no documentation or discussions of its trimming requirements at all, which would indicate to me that it was fairly well-behaved by the standards of the day (it was well-enough known as an easy aircraft to fly that even German pilots would say "Anyone can fly a Spitfire," which implies to me that they considered themselves more manly because they had tamed the 109...). Yet the Il-2 Sturmovik Spitfires demand a lot of trim adjustment, about the same degree as the Mustang, although with the added difficulty of that hard to read Turn and Bank needle arrangement.

In short, in this simulation these specific aircraft are much harder to trim and control than the real ones were, particularly when measured against the other WWII fighters depicted in this sim, and all of them demand un-historic trim adjustment in the form of multiple button presses for relatively minor variations in speed and throttle settings, as well as climb or diving conditions, and it is next to impossible to roll your trim settings to a set position in anticipation of a sudden change in speed or throttle, as the real-life pilots did regularly.

Exaggerated behaviors like the ones we experience in this sim would have made these fighters practically unacceptable as combat aircraft, and make "historical tactics" next to impossible. No amount of brains in the world is going to change that.

cheers

horseback

[majorfailure]

Originally Posted by horseback

The real P-38 needed NO elevator (or rudder) trim for speed and throttle variations (per America’s Hundred Thousand), but the Il-2 Sturmovik Lightning will go literally straight up when you push the throttle forward without shoving the stick three quarters of the way forward at the same instant and punching the elevator trim button constantly for as long as the speed continues to increase. (and it's a lot slower than the real thing was)

That makes no sense, as this would mean the P-38s wing would generate the same lift all over its speed range. But compared to http://www.wwiiaircraftperformance.org/ data its speed seems fine.

Originally Posted by horseback

The real life P-47 needed no elevator trim for initial acceleration, but the in-game version does the same thing as the Lightning, with the added entertainment value of needing a ton of right rudder as well, and like the Corsair, the nose tends to dip as speed increases in the level plane; by this I mean that the angle of attack varies significantly with speed, something I've never read or heard about in these aircraft in over 45 years of reading, modeling or personally talking to men who flew these aircraft (you'd think that somebody would have mentioned it...).

And how else if not with changing AoA should a plane regulate its lift when changing speed? Faster plane - wings generate more lift with same AoA, to keep the plane level AoA needs to decrease.

Originally Posted by horseback

As for the Spitfire, I have no documentation or discussions of its trimming requirements at all, which would indicate to me that it was fairly well-behaved by the standards of the day (it was well-enough known as an easy aircraft to fly that even German pilots would say "Anyone can fly a Spitfire," which implies to me that they considered themselves more manly because they had tamed the 109...). Yet the Il-2 Sturmovik Spitfires demand a lot of trim adjustment, about the same degree as the Mustang, although with the added difficulty of that hard to read Turn and Bank needle arrangement.

I'd think the reference that anyone could fly a Spit does not mean the plane is trimmed easily, but it is easy to fly in combat maneuvres, and it does not stall viciously and recovers good (I'd think the IL-2 Spitfire meets all those criteria).

Originally Posted by horseback

In short, in this simulation these specific aircraft are much harder to trim and control than the real ones were, particularly when measured against the other WWII fighters depicted in this sim, and all of them demand un-historic trim adjustment in the form of multiple button presses for relatively minor variations in speed and throttle settings, as well as climb or diving conditions, and it is next to impossible to roll your trim settings to a set position in anticipation of a sudden change in speed or throttle, as the real-life pilots did regularly.

Yes, we need some indicator or gradation or whatever to see where trim currently is, and how much we apply. Then one could remember:
SpitIX, 90%, 3.5k alt, left 7 (or 1.5° or whatever) trim, down 34 (or XX° or whatever) trim - flies straight. Currently we can only do this if we reset trim to 0 and then apply trim settings, but this is counterproductive, 'cause except at landing speed a Spit with neutral trim severly noses up.

[horseback]

The following paragraphs are taken whole out of America’s Hundred Thousand by Francis Dean. These are the complete sections labeled Trimming with nothing left out. Bear in mind that these are all American fighters, and any comparisons the pilots quoted herein are to other American fighters, not the Zero, not the Spitfire, not the Lavotchkin and not the Bf 109. This is just part of the picture the author paints; the sections on Ground Handling, Takeoff & Climb, Dive & Recovery, Maneuvering, Approach & Landing, Stalls & Spins, and the Gun Platform and Weapon performance paint a pretty complete picture of how these aircraft flew from a generally American perspective. Most tend to reinforce the picture painted in the Trimming sections. I have underlined or italicized key words or phrases in some cases.

I simply lack the time and patience to transcribe all these in full, even assuming that it would not violate some copyright rules. I would recommend however, that anyone who wishes to argue the point transcribes at least the full paragraph that he is citing instead of engaging in the usual cherry picking.

One interesting note: The second paragraph in the P-40’s Maneuvering section starts with “…P-40 airplanes were very maneuverable for US Army fighters, some said better than a P-51.”

Trimming Sections from America’s Hundred Thousand:

P-38

The P-38 could be trimmed out to be pleasant to fly, and trimmability was rated good to fair by the majority of pilots in one survey. No adjustment of rudder or elevator trim was required with power or speed changes.

P-39

P-39 trimmability was good. Elevator tab action allowed stick force to be trimmed to zero throughout the speed range. Aileron trim changes with speed or power were negligible to 400 mph IAS. Above that speed, there was an erratic trim force change, possibly caused by aileron fabric bulging. There were directional trim changes in climbing and diving, but they were not extreme.

P-40

A major aspect of flying the P-40 series airplane was handling trim changes from power and speed changes. A veteran AAF pilot stated “The trim changes with speed were more than in other contemporary fighters.” Typical of many single engine propeller fighters, the vertical tail fin was slightly offset to counter propeller slipstream effect at cruising speed. In a dive, as speed increased, more and more left rudder had to be added; slowing down in a climb some right rudder was needed. One pilot said “—a drawback was having to virtually stand on the left rudder pedal to keep the ball centered—it could be a real handful in a loop” (where trim reversed from dive to climb and then back again). Although directional trim tab power was available to zero out pedal force, left rudder trim could not be rolled in fast enough with high dive acceleration. No matter what P-40 version was involved, it was the same: “In the air, the Tomahawk tended to yaw considerably with speed changes”, needing directional trim, and for the P-40E/H87A: “Every power and speed change brings an immediate trim change which the pilot must either counteract or trim out”. The H87 was, if anything, worse than the H81 Tomahawk.

On the P-40E lowering the landing gear made the aircraft slightly nose heavy; there was no appreciable trim change with flap positioning. Dropping a belly tank resulted in minor tail heaviness. The elevator trim system could take care of these effects as well as longitudinal variations due to speed and power changes.

P-47

There were some differences in trimmability between models. “The P-47D-25 trimmed harder than the D-15” but generally longitudinal and lateral trimmability was satisfactory on the P-47, and the tabs were very sensitive. There was very little trim change with gear retraction and initial acceleration; dropping flaps made the airplane slightly nose heavy. Longitudinal trim changes with power and speed changes were small, and elevator tab power was sufficient to trim stick forces to zero at all speeds and all normal center of gravity locations. The aileron trim tab action was sufficiently powerful for all flight conditions, and the rudder tab could trim pedal forces to zero at all speeds above 120 mph IAS in the power on clean condition. But as with other fighters, like the P-40, the rudder trim force change with changing power or speed was objectionably high.

P-51

ALLISON powered Mustangs were particularly notable for lack of required trim changes. Power or flap setting changes gave only small trim variations, and the same was true of gear retraction. The changes in tab settings for climbing and diving were negligible. Tab controls were sensitive and had to be used carefully.

Trimmability was also quite good in MERLIN Mustangs, and tabs were sensitive. In these versions directional trim changed more with speed and power changes. When the rudder trim system was changed and rigged as an anti-balance tab to give opposite boost, a resulting disadvantage was more tab was required to trim the aircraft from a climb into a dive.

Along with trimming the airplane for longer term steady flight conditions, some pilots trimmed their aircraft almost continuously to wash out any high stick or pedal force during maneuvering in combat.

F4U

The Corsair was easy to trim out for climb. Trim changes from landing gear and flap retraction were minimal, and those for speed and power changes were quite handleable. In cruise condition the airplane could be trimmed for hands and feet off flying with little trouble. Pilots almost universally rated F4U-1C and -1D trimmability as good. In a dive, as with some other US fighters, a considerable amount of rudder trim was required to zero out pedal force which was high if this was not done.

F6F

There were nose up trim changes with gear and flap retraction, though they were minimal, and the same was true of initial acceleration into climb. In general, there were substantial trim changes both directionally and laterally with speed and power changes, but tab action allowed trimming out control forces to zero except for the rudder. At low speed and high power rudder pedal force could not be trimmed out fully. Most pilots thought trimmability was generally good, though some made the following comments ‘Lack of trimmability”, Excess rudder trim change”, and “Aircraft requires excessive trim” (three pilots). It was noted that in a dive control forces could not be trimmed out quickly enough.

MY COMMENTS:

P-38: the in-game model forces you to apply a LOT of nose down pressure and trim when you apply power, which contradicts the description from Dean. It is also quite a bit slower to accelerate than the in-game P-51B/C, which just doesn’t make sense, if you look at the test records, even those comparing the early P-51Bs without the fuselage overload tank. From the descriptions from several wartime pilots’ memoirs and historical reports as well as from America’s Hundred Thousand, I expected that the Lightning would ‘dither’ for a tiny split second before surging almost straight ahead when full power is applied, but the in-game version will immediately head almost straight up when 100% prop pitch and full power is applied if you don’t anticipate it and force the stick/yoke well forward immediately and start punching in nose down elevator trim with your eyes fixed closely on the climb & dive indicator. I expected to dial in some trim as speed increased, but I didn't expect to have to bang the stick almost all the way forward just to stay level.

P-39:A bit of a shock when I read Dean’s comments on the Airacobra; I thought it would be a bit of a trim hog, but instead the real thing seems to have trimmed out fairly easily at most level speeds. The problems it had were apparently not due to trimming issues so much as the sensitivity of its controls compared to other fighters of its time—I assume that unless the pilot had fully mastered its (several) unique quirks, he could get himself in trouble if he fell back on ‘muscle memory’ acquired in other types. The in-game ‘Cobra is a bit twitchy (you always feel like you are balancing on the head of a pin) and at the same time a bit too good if you don’t remember that the ‘Cobra’s issues with the USAAF in the Pacific in 1942-43 were more because of poor maintenance and field reassembly of hurriedly shipped in aircraft due to a lack of experience and documentation rather than to poor design or quality of production at the factory.

P-40: The Tomahawk and Warhawk were considered to be among the most maneuverable of the Western built fighters in WWII as long as they stayed below 15,000 ft, but it took a very good pilot (and a strong one, at that) to get the most out of it. It was not a good aircraft for persons with attention deficit disorders, because it was notorious for needing constant trim and engine adjustments—nobody relaxed in a Warhawk unless it had been on the ground with the engine off for a good twenty minutes. After mastering the P-40, most WWII pilots would find almost any other fighter of the period relatively easy to control and exploit (the P-38 was easy to fly but hard to master, but veteran combat groups in the Pacific transitioned into it seamlessly from the P-40). I was well aware that the P-40 series was considered very tricky to take off and land, and that taxiing it was considered a bit of a trial, so the Il-2 Sturmovik Forgotten Battles/’46 depiction has always seemed far too user friendly to me. In-game, it requires much less trim adjustment than even the P-39, and is one of the easiest fighters in the game to master. It is by far the most charitable depiction out of all the American built fighters depicted in the game.

P-47: This one is like the P-38 in some ways; in-game, the elevator trim is consistently excessive, and the rudder is fairly easy (too easy, if Dean is to be believed) to adjust. In-game, at 270kph/170 mph, it wallows like a pig and is seriously unstable with a pronounced nose high attitude, which hardly makes sense for a range of speeds that was commonly used for economy cruise and landing approach. In addition, the angle of attack will lower significantly as speed rises, which makes it hard for the pilot to judge whether he is actually keeping anything like level flight, and will complicate your firing solution when diving on an opponent. Like the P-38, the in-game P-47 wants to go sharply up the moment power is applied, and it also wants to turn left because of torque and p factor; if you don’t apply significant nose down pressure on the stick and kick in a LOT of right rudder as you punch the throttle and prop pitch forward, you’re going to waste all that power going in the wrong direction. Again, given the weight of the Thunderbolt, I would expect a slightly longer ‘dither’ than the Lightning, but it should surge more straight ahead than up, at least at first. Also, my reading leads me to believe that the P-47 was pretty fast in a straight line, even if it took a while to get there (especially with the early ‘toothpick prop’ versions) at lower altitudes, while Il-2 Sturmovik ‘46’s depiction makes it not only slow to reach top speed (and very prone to overheat) at 10,000 ft, but that top speed seems a bit short of what it should be.

P-51C: The Mustang should be the easiest US fighter in the game other than the P-38 to trim in almost any conditions by a fairly wide margin, if we are to believe Dean and testimony from pilots of the era. The consensus seems to be that the in-game Mustang demands elevator and rudder adjustments for every 10kph/5mph variation in speed. To put it lightly, that is bogus; Dean’s description says that the Merlin Mustang’s trimmability was “also quite good” in obvious reference to the standard of the Allison powered versions which needed almost no trim adjustments for speed or power changes.

The flight models of both the DCS Mustang and the Wings of Power P-51D for FSX tell me that the rudder trim requires slight adjustments for power increases of 10-15% (5-8 inches of added manifold pressure)or speed increases in the 25-35 mph (40-55 kph) range and that the elevator trim hardly needs touching at all, which is consistent with wartime reports and comparisons that suggest to me that the Mustang was rated more highly in maneuverability than it might have technically deserved because it was much more easily flown with precision than its contemporaries;; i.e., a Mustang pilot could take his aircraft to its limits with more confidence right away than the pilots of other high performance fighters of the period—there was considerably less of an exploratory period needed for it.

The in-game version’s extra acceleration, which is clearly superior to the much lighter Spitfire Mk IX, seems like an attempt to mollify those players who know that the Mustang was one of the all-time great fighter aircraft—the difficulty of bringing your guns to bear because of oversensitive elevator and rudder trim (added to the sheer unreliability of the needle and ball the microsecond you stray from the straight and level) or of achieving coordinated maneuvers are supposed to be excused by the old song and dance about superior training & numbers, plus the—(“See? See? We didn’t really nerf it.”)—speed and range.

F4U:This one is treated a lot like the Mustang in that it has been given almost spectacular speed, but it needs an awful lot of trim adjustment to maintain its E advantages. The moment you start to roll into a turn or pull up into a climb, you will be out of trim and bleeding energy in arterial spurts. Again, this seems to be contrary to the historical record. It is also like the P-47 in that the angle of attack in level flight changes radically (it seems like a drop of several degrees, but if we use the gunsight circle as the standard, it is about half to two-thirds the circle’s diameter down from the 270kph starting speed) during acceleration, but not so much at the same speeds when flying back to the starting point. At certain speeds, it will seem to drop suddenly (or else I’ve been very consistent about over-applying the nose down trim), and the pilot has to pull up on the stick sharply but very precisely in order to stay level.

F6F: With this one, you are almost constantly adding and subtracting trim; three clicks nose down to get it to react, then one or two up to correct, wait two seconds and then repeat the process. Again, once the initial rudder trims are made, it seems to stabilize directionally (which seems to me to contradict Dean's description). Bear in mind that we are talking about speed changes of 10 kph, or a bit over six miles an hour; there's quote in the P-40 Comments section where one pilot complains that he had to make adjustments for every ten miles an hour, or about 16 kph. If adjusting for 16 kph variations in speed are excessive, what does that make adjustments (and I mean absolutely necessary adjustments; if your attention wanders for two or three seconds, your altitude can change by two or three hundred feet at those speeds) for speeds of less than two thirds of that?

In every case except for the P-40 (which appears to be sort of a charity case), the trim requirements are grossly excessive. Compared to say, the Ki-43 or Ki-61 (or any late-model Soviet fighter), the elevator trim requirements in particular for late model American fighters (and the Spitfire, for that matter) are cartoonish, especially for the Mustang and the P-47. In fact, I would class the trim modelling for the Mustang, P-47 and Hellcat about one and a half to two times what should be required for the P-40 in the context of this sim.

The 'straight up' when accelerating tendency in the P-47 and P-38 is counter-intuitive; these were big heavy fighters, and as Dean confirms, should surge almost straight ahead at first, especially the P-47, which like the P-40, was well-known to almost resist entering a climb from level flight. The AOA thing is particularly troubling in aircraft that need to land on a carrier. I could accept some drop in the nose as speed increased, but not to that degree. Of all the fighters of WWII that I have read any amount of information about, only the Focke-Wulf was acknowledged as having a lowered AOA with cruising/combat speed (and I recall some howling over the Il-2 Sturmovik/Forgotten Battles Butcherbirds lacking that feature).

In my test runs so far, the FW doesn't seem to dip as much as the Corsair, Hellcat or P-47; I'm going to have to take a few screenshots for comparison while I do my sea level tests, since the horizon will make it easier to judge.

As I have said, anyone should be able to duplicate my results and see for themselves what I am describing. If you normally place your stick on a keyboard tray, I would recommend that you make sure that you have enough clearance from the desk edge so that you won't lose the skin off your knuckles when you have to shove your stick forward after you punch the throttle.

cheers

horseback

[horseback]

Originally Posted by JtD

Regarding trim, both the F4U and the F6F as tested by NACA required loads of elevator trim. Stick force changes were in the range of 30lb between 200 and 400 mph in level flight. Trimmed for neutral stick forces at low speed, pilots would sometimes not be able to keep the aircraft in a dive.

Trim as suchs seems to have been a bit more effective than it is in game.

I use Francis Dean's America's Hundred Thousand as my primary reference in these things, as well as Barrett Tillman's The Wildcat in WWII, Hellcat: The F6F in WWII, and Corsair: The F4U in WWII and Korea to supplement for 'hard knowledge' on these particular aircraft. I've also had many occasions to talk to men who actually flew these aircraft (my landlord in Coronado many years ago was a former Wildcat, Hellcat and Corsair driver, getting combat time with the Grummans in WWII and with the F4U in Korea; he introduced me to several of his wartime buddies after he noticed my extensive model collection --and bought all my blue airplanes).

On trimming the Corsair, America’s Hundred Thousand says: “The Corsair was easy to trim out for climb. Trim changes from landing gear and flap retraction were minimal, and those for speed and power changes were quite handleable. In cruise condition the airplane could be trimmed for hands and feet off flying with little trouble. Pilots almost universally rated F4U-1C and -1D trimmability as good. In a dive, as with some other US fighters, a considerable amount of rudder trim was required to zero out pedal force which was high if this was not done.”

One the Hellcat’s trim characteristics, it says: “There were nose up trim changes with gear and flap retraction, though they were minimal, and the same was true of initial acceleration into climb. In general, there were substantial both directionally and laterally with speed and power changes, but tab action allowed trimming out control forces to zero except for the rudder. At low speed and high power rudder pedal force could not be trimmed out fully. Most pilots thought trimmability was generally good, though some made the following comments ‘Lack of trimmability”, Excess rudder trim change”, and “Aircraft requires excessive trim” (three pilots). It was noted that in a dive control forces could not be trimmed out quickly enough.

The old Naval aviators I talked to felt without exception that the Hellcat was the easiest aircraft they ever flew off a carrier deck, prop or jet. Of course, most of these old guys were raised on farms or worked at a job demanding a fair amount of physical strength (by modern standards) so a 30lb force difference probably wasn't all that excessive by the standards of the time, especially if you could easily adjust it out with the trim tabs. To be honest, 30lbs (or a bit less than 14kg) doesn't sound like that much to me, but I spent many hours in the pool and the weight room as a younger man.

In-game, trimming out these aircraft is not close to 'easy'.

The point is that many of the aircraft modeled in this sim are based on reports and tests done 70 years ago, and what were called 'mild' or 'light' stick or rudder forces might seem a bit heavy to the average man today. It may not be appropriate to add (over)detailed characteristics to well understood and documented aircraft that have to compete with aircraft that are modeled on older standards that cannot be verified to match the current ones.

Now if you all will excuse me, some miserable sod has released a new patch, and I have to start re-running all of the 100m tests I've done so far...

cheers

horseback

PS: During the early phase of my tests, I ran the trim all the way out in both directions on a number of aircraft, doing both rudder and elevator, as well as a few ailerons; it takes 80 button pushes in each direction from CENTER, or 160 button pushes from one extreme of trim offset to the other. By comparison, using the CH Quad, a tiny increment seemed to have much greater, but much less predictable results. Pick your poison.