A game designer's viewpoint on AHWiki's aircraft descriptions.

[Angus]

Ehm?
"   Spit XIV: From the Mk IX onwards, the Spitfire's roll rate became less than two-thirds of what the Mk V could achieve, and this with the SAME early peak in the speed range, that is, of around 200 MPH TAS(!). The Mk V's highest roll was about 70-78° per second at this 200 MPH TAS point. The Mk IX was 2/3rds of that according to the Supermarine's factory test pilot, so about 50° per second, getting WORSE afterwards... The Mk XIV was slightly worse than this, with the SAME early peak, as is borne out by MK XII roll data, which indicates a peak of 35-40° per second at 200MPH TAS. Outlandishly, Farnborough's well-known side-by-side tests indicate a "generally" superior roll rate for the MK XIV versus the P-51... If you search VERY long on this absolutely bizarre claim, you will find a comment saying "The MK XIV's ailerons were defective but will be fixed in production". THIS is what besting the P-51's roll rate is based on; a test pilot's wishful thinking... A major feature of most Spitfires is in fact slow ailerons, leading to the Galland comment; "great for aerobatics, but ridiculous for fighting". Clipping the wings helped moderately at low altitudes mostly, and the MK V's 78°/sec. at 200 MPH could be the top Spitfire figure if clipped, as 60-70°/sec. seemed common. This would put the MK IX peak at a 40-45°... Obviously, the NACA 868 roll chart's Spitfire figures are not valid for any mass-produced wartime Spitfires...

   Another feature of all Spitfires is a slow initial turn, getting worse at high speed, because a movement of the stick top of more than 3/4 of an inch will cause it to mush forward in a controlled stall. This could be used to gain a firing lead, mind you, but at a great loss of speed or at the risk of "bending" the aircraft at high speed. Though very useful offensively, this is not really an impressive feature of the turn for escaping a pursuing ennemy, and it demonstrates a remarkably poor lift for such a large wing... The high altitude dive speed mach number is outstanding, but at low altitude it is the rigidity of the wing against buffeting, not the mach number, that makes a good diver. The Spitfire does no better than the 109's fluttering ailerons below 20 000 ft.."

Lots there, don't know where to begin, but the whole roll rate claims here remind me of Izzy.
As for the turning claim, that one leaves me puzzled as well.
And the Wing lift, well as a total the lift was quite okay;) Look at the Spits ROC for the horsepowers.

[Gaston]

       Thanks for your responses, I am pleased to see how rational and level-headed they have been. I usually post on aircraft modeling sites (the scale plastic variety), and if these guys were here they would demand to know how many times I have flown the real thing...

       I will try to clarify the points I made about the Spitfire and NACA 868 in general.

       Believe me, I am the last person who would dismiss the NACA chart 868; I think this is probably one of the greatest single discovery about WWII aircraft maneuverability ever made. The 109G is sadly absent, and thus its roll rate is still a matter of debate. 109F charts do exist, and show a much higher speed for the roll peak (350 MPH TAS) than usually assumed, with peak values ranging from 85° to 109° per second. I would peg the G at 70°-80°/sec at 350 MPH, worsening to 50°/sec below 250 MPH.

       Note that the Zero roll rate is labelled "stick force unknown", and that this is critical, because all Zeroes had outstanding roll up to 200 MPH, being close to 100°-120°/sec(!) at a low 120-150 MPH, this always going down after, and ever more steeply after 250 MPH TAS...

       [Of note with Japanese aircrafts is that most of their speeds are quoted at Military Power, NOT War Emergency Power. In comparison, the Japanese WEP was usually longer, for instance, than the 109G's 3 minutes (I suspect the 10 WEP minutes-capable MW-50 tank of the 109 often went unused for logistical reasons...). I estimate the Ki-84 topped out at 690-700 km/h, the A6M5 at 590-600 km/h, the Tojo is quoted in a report at 640 km/h. And so on...]

        Getting back to NACA 868, you will note that the Spitfire Mark is not specified on the chart, while the specific model is specified for almost all the other, conveniently obsolescent, types. This should immediately draw our undivided attention; the year of the report was 1947, and there were still MANY Spitfires in active service with many nations friendly to American interests. Moreover, in Indochina and elsewhere, many of these Spitfires were in active combat, and keeping the info blurry on these and CURRENT British aircrafts might have been seen as the polite thing to do...

       As for what the NACA 868 Spitfires actually were, an indication here with these clipped MK XII tests;

       http://www.spitfireperformance.com/mk12roll.gif

       This from the excellent "WWII aircraft performance" site.

       So the CLIPPED Mk XII ranges from 25° to 50° per second, roughly. 38°-25°/sec to right at 300-400 MPH, 50°-40°/sec to left at 300-400 MPH. The unclipped wing substracts about 6°-8°/sec. to the left at high speed and that's it. I ignored the poor performance of EN 221.

       Note the unusual preference to dip the LEFT wing at higher speeds; most other aircrafts above 250 MPH have a preference to the RIGHT; but here the spiral of air spins in the OPPOSITE direction; the Griffon propeller turns the other way... Below 250 MPH, the reserve power of the engine turns UPSIDE-DOWN the preference, under acceleration, because this time the stronger TORQUE of the propeller twists opposite against a much weaker slipstream spiral. It is then that the Griffon torque wants to dip the RIGHT wing, again opposite to what most others fighters do at low speeds, and again for the same rotation direction reasons...

       Some may find things to quibble, but my feeling is that the above Mk XII performance is probably slightly superior to what we can expect the real, heavier, Mk XIV to do, and is in fact more a mirror image of the MK IX... The Mk IX is slightly better than the MK XIV, if the Supermarine factory test pilot is to be believed, so my guess for the MK XIV would be a range of 40° to 20°/sec. instead of 50° to 25°/sec., from 300 to 400 MPH.

       Obviously the 140°/sec of the NACA 868 chart are from another dimension; ie; fully re-designed wings of the post-war Marks...

       Note that the Mk XIV was produced in fairly modest numbers, a clear sign to my eyes that it was not seen as a huge success.

       Let's disgress for a moment, and consider the strange fact that a MK IX augmented to +25 lbs (colored 150 fuel) will OUT-CLIMB a MK XIV at +18 lbs, yet fails to gain 1 MPH from this extra 350 hp(!), being 40 MPH slower than the +18lbs MK XIV, despite having nearly the same power: ?!! : Radiator design, supposedly...

       Does the slow roll rate mean the late Spitfires were crap? Not entirely. Take the ability to point the nose across the turn in a high speed "mushing" stall; very good offensively when the enemy numbers are dwindling, but bad defensively when they are numerous and behind you.

       Much as I love the roll rate as a maneuver feature, in my game at least its importance is exaggerated. The Spitfire is probably the worst rolling pure day fighter of WWII; pilots flew around the problem quite well, and it did out-climb and out-accelerate ANYTHING, including ALL 109s... Where the Mark XIV was supreme was at high altitude, where its heavy ailerons may have lightened up and its climb rate was comparatively even more incredible. Other than this narrow high-altitude point defense role, I think it is fair to say that with its more rigid wings, the Me-109 had aged slightly better, if you discount its small, and diminishing, endurance...

      Gaston.



    

      

      
      

      

      
    

[thrila]

       Let's disgress for a moment, and consider the strange fact that a MK IX augmented to +25 lbs (colored 150 fuel) will OUT-CLIMB a MK XIV at +18 lbs, yet fails to gain 1 MPH from this extra 350 hp(!), being 40 MPH slower than the +18lbs MK XIV, despite having nearly the same power: ?!! : Radiator design, supposedly... 

Spitfires gained speed with 150 octane at low alt, generally 20-30 mph.

http://www.spitfireperformance.com/merlin66_18_25.jpg

[Anaxogoras]

I like the part about the 190A-8 being a good stall fighter.

[Noir]

I like the part about the 190A-8 being a good stall fighter.

I'm curious about that too.

[BnZs]

I like the part about the 190A-8 being a good stall fighter.

Well, all sources agree the 190 series didn't have the best rate or radius of turn.

SEEMS rather odd, but it could be argued that with the performance disadvantage German fighters tended to experience above 20K vs. the American opposition, forcing the horizontal scissoring fight might have been the best option.

Going by the wingloading and CLmax, seems like the 190 A5 ought to at least somewhat turn with the P-47 at low alt where it has a power loading advantage.

[Kev367th]

   
       Let's disgress for a moment, and consider the strange fact that a MK IX augmented to +25 lbs (colored 150 fuel) will OUT-CLIMB a MK XIV at +18 lbs, yet fails to gain 1 MPH from this extra 350 hp(!), being 40 MPH slower than the +18lbs MK XIV, despite having nearly the same power: ?!! : Radiator design, supposedly...
 

As thrila pointed out at low alts the 25lbs LFIX did gain approx 20-30mph.

However comparing a Griffon based (hi alt) XIV to a low alt Merlin 66 LFIX is absurd.

The XIV will outclimb the LFIX at high alts WITH EASE.

Horses for courses.
XIV - Hi alts.
LF IX/XVI - Low alts.

A much better comparison is the orignal Merlin 61 based F IX against the F XIV.

[SmokinLoon]

Another question I'd like to know the answer to is this:  Has HTC seen this data already?  Or is this stuff new to them?  If they have seen this data then why are there same major descepancies between AH2 aircraft models and the historical data???

If this data is new to HTC... I hope they are paying close attention.   

[humble]

I'm not sure about the A8 but numerous historical accounts exist of the early 190's (A3/4) just dominating the spit V's over France. The surprise was that the 190's abandoned the normal hit and run tactics and "mucked it up". While the A5 is a reasonable dogfighter when flown to its strengths I do think its raw turn capabilities are a bit under modeled. The 8K floor is correct, but what I read is a bit different. The A4 had a high speed accelerated stalled at 322 mph at high G loading. Very few pilots proved capable of catching the tip before it departed and the recovery proved very difficult. The restriction was on dogfighting below the 8k "hard deck" for that reason...

[Charge]

Well for starters I have read about a clim that 109G could maintain 60 deg nose up attitude while flying otherwise horizontally level. Now if that is true what does it tell about its strengths as a turn fighter? Also interesting is J. Meimberg's story in his book about his duel with Egon Meyer how Meyer's 190 was already "hanging from its prop" and from there started a duel which took quite a while and ended in a tie. Thats probably A6 against a G2. No doubt how that kind of stall fight would end in AH.

Awhile ago I also posted link to a Russian report which claimed that the 190 would always try to turn inside LA5 and best defense would be a prolonged vertical fight to make the 190 to bleed its energy because it was a heavier aircraft.

About NACA 868 and Spitfire roll rate: If you read the document you find that the features that make a good roller are found mainly in FW190, not in Spitfire, and the chart which shows the Spitfire catching 190 in roll performance in high speed highly doubtful as in high speed the wing warping of that large wing would take care that 190 would not have to worry about Spit matching its roll, IMO that is. The newer wing was another matter which I cannot comment since I have not read about pilots experiences about those.

The internal (box?) structure of 190's wing made it torsionally very stiff and the fuselage resting on top of solid bars made the wing strong even in high speed pull-outs. The tubular spar structure of Spit is very strong (due to flexibility) in this sense too but rest of the structure does not support its torsional stiffness. I even recall a Spit veteran telling how the outer machineguns in Spit were quite useless in high speed fights as they tended to fire here and there but not the enemy in sights, again indicating that the wing indeed did warp torsionally. Of course the wing clipping was a good move as was discussed in another thread, but I don't think it could match 190 in rolling performance in any speed until the wing was completely redesigned if even after that.

After all fighter design is full of trade offs and some features can be used to counter others but no fighter holds all the cards.

-C+

PS. "seems like the 190 A5 ought to at least somewhat turn with the P-47 at low alt where it has a power loading advantage." There is also a film available of a (claimed) FW190 turning with a P47, turning inside it and even pulling lead for a shot and at the same time you can see vapour trails coming from wing tips of the P47 as it tries to turn tighter. Of course it does not tell much but, at least to me, it certainly tells me about 190's turning ability in some speed range.

[BnZs]

Well for starters I have read about a clim that 109G could maintain 60 deg nose up attitude while flying otherwise horizontally level.

Not too much. You fly normally with the nose pointed straight up until you run out of air if you have enough thrust to do so. Jet fighters can do this but that doesn't mean they can match a WWII prop job in turn radius.

Also, I cannot see how the 109 could have been pitched up at 60 degrees relative the Earth *and* literally flying level relative the Earth, as opposed to climbing. If that is really what is being described Wouldn't that put it well past the AoA for stall? Leading-edge slats can raise the critical AoA for a wing, but raise it to 50+ degrees???

[Gaston]

      Of course the Spitfire IX/XIV comparison was NOT at matching altitudes; the Spit IX outclimbed the XIV at a broad band of LOW altitudes, while the Spit XIV was faster throughout but more so at high altitudes, where it outclimbed everything else, including the +25 lbs MK IX...

     I was just making absolute comparisons I thought were unexpected and significant. Note that the +25 lbs (80 inches MAP) Mk IX is 20-25 MPH SLOWER than a 67 inches MAP P-51D, which has the same engine and 350 fewer hp(!), and the +25lbs MK IX was, in addition, 30 to 40 MPH SLOWER than a P-51B with 72 inches MAP(+21 lbs) and 150 fewer hp(!). Of note is that the +21lbs P-51B was no slouch climber in its own right, and was beginning to match a basic 109G-6, provided it had the -7 engine (about half the B-C production).

     Of course the +25 lbs Mk IX absolutely crushes EVERYTHING in low-medium altitude climb rate, but the interesting point I wanted to make was that it apparently had little else. Perhaps the gap in speed at lower altitudes was less, but it kind of gives one pause when a fighter like the P-51 that has 350 fewer horses, with the SAME engine, and weighs thousands of pounds more, is still about 12-15 MPH FASTER at most altitudes, and about 20-25 MPH(!) faster at some of the higher altitudes...

    As a comparison, the Me-109 radiator drag did not creep up with the increase in speed and power, so that when the G-14 added 300 hp, maximum speed did go up at ALL altitudes by 8MPH, and hugely so (+20-25 MPH)at low altitudes (but was rarely present, especially in later G-10s/K-4). When later G-10s and K-4s had the undernose oil cooler redesigned, this also added 8-12 MPH at ALL altitudes, and the AS/G-10/K-4 supercharger added to that another 10-12 MPH at higher altitudes.

    Increases in power in the 109 led to a higher maximum speed AS WELL as more speed at lower altitudes (except in some oddball K-4 Russian tests, due perhaps to the condition of the aircraft). In the Spit IX, some of the extra power went to low altitude speed,  but most of all it seemed to go mostly into its monstrous climb rate. A sort of one-trick poney that was essentially converted into a fighter-bomber with the heavier and longer-legged MK XVI.

    Note that the climb rate advantage of a +25 lbs Spit IX versus a late 109 was exaggerated further by the fact that MW-50 could not be used for prolonged climbs (or dives!), the issue being I think oil circulation at sustained nose up angles. In prolonged dives, MW-50 would detonate the unloaded engine... (In any case, I think MW-50 was rare in the 109 after its few first months, because it required C-3 fuel that had to go to the 190 which could fly with nothing else.)

    It is not my intention to disparage the beautiful aircraft that was the Spitfire. However, it does seem to me that despite the high speed controlled mush and its absolute climb rate superiority, advantages it retained all the way to the end of the war, the above does seem to indicate a less well rounded aircraft than usually assumed. The aging 109 definitely seemed to be holding its own better, and with infinitely fewer design changes... The only really totally obsolete feature of the late-war 109 was its endurance, and even there the Spitfire was not much better until the MK XVI was loaded down with fuel for its fighter-bomber role...


    Gaston.

    

[texastc316]

 

I had that game back in the 80's

[Murdr]

Gaston,

Just to point out, every AHWiki aircraft page is headed with:

This aircraft page is in two sections:
Historical information about the {plane type} in World War II; and

Information about the {plane type} in the massively multi-player online combat simulation Aces High II.

To date, all the maneuverability information that I am aware of is contained in the AHII section of the pages.  The information there is not only contexted by the AH flight model, but also by the arena format of AH itself.  There are mutiple arena setups availible, but the vast majority of players congregate in the format where all planes are availible for all countries. 

So the context is that in AH late war arenas you may encounter combat with any of nearly 80 plane varients modeled in the game, and performance information is colored accordingly.  For instance, with the 109G, depending on which varient, loadout options, and gross weight, the Cv for clean configuration could be anywhere between 230 mph, to 250ish mph.  Anywhere above Cv, the planes best rate of turn is on a decending trend, and being limited by the pilots G tolerence.  So the games flight model itself gives the best turn performance below 250, but in the gameplay environment a typical AH player will be using it in, any 109G has a number of planes to contend with that will out class it in rate and radius of turn.  When you place it in that context, it makes sense to advise to keep it between the top end of corner velocity, and VNE, so that the option to disengage is there when facing a more nimble plane it would never have historically faced.

[Gaston]

 
    I understand what you are saying, the CV means that past a certain velocity, the increasing turn rate shifts to an always descending trend.

    I think this concept is inherited from jet air combat, where "energy" has a great role to play, because the range of speeds is so vast compared to WWII. The "CV"; the speed at which the turn rate "peaks", is always very low compared a jet's maximum speed, so it is crucial to adjust CORRECTLY between that and the top speed to get where you want to go; thus the slowing "high yo-yo" versus the accelerating "low yo-yo"; terms and maneuvers I have never heard from WWII pilots accounts, which are absolutely bread-and-butter to jet fighter pilots...

    When you listen to WWII accounts, the "energy" (which I read as "excess relative speed") counts less than the altitude advantage and acceleration. Also the CV "peak" was not linear, limited to one, or similar in shape among these vastly idiosyncratic aircrafts. The Me-109G had two CV "peaks", with a big hole in the middle, the P-47 and P-51 had very late CV "peaks", which meant their best turn rates could not be sustained without making a descending spiral, because the engine had no reserve power at this best turn rate, so close was this to the maximum level speed.

    With altitude, a WWII fighter could make a high speed attack/getaway (boom and zoom), but an overlooked aspect of this "energy fighting" is the exaggerated effectiveness of the gun armament in computer games; in reality, the higher the relative speed, the weaker the armamament strike. The more energy you have compared to your opponent, the more bullets/shells will miss. In WWII they HAD to stay and maneuver to finish the job, and they could not attack at too high a relative speed. This is why the Me-163B was so hopeless, despite an armament that could crush any foe. This was simply not how guns allowed the game to be played...

    The exception to the above was combat against Japanese aircrafts, where a few hits would ignite the large long range unprotected fuel tanks of the Japanese, and where the higher speed actually minimized the maneuverability disparity between Japanese and American aircrafts. Here is a WWII situation where excess relative speed was actually useful...

     In Europe there were more maneuvering contests. The Germans faced a disadvantage due to the low fuel situation; no permanent Combat Air Patrols (CAP) were possible; fights were entered after a long climb with a hot engine. This probably lost them the acceleration parity they had a higher altitudes, making it impossible for them to avoid the descending spiral or dives that so favored the P-51 and P-47's best turn rate. A turn rate peak (CV) which, without altitude loss, could not be sustained, so near was it to the maximum level speed of these two American fighters...

     To summarize, my point is that during WWII, the weakness and range of the gun armament did not allow "energy fighting" to the extent of applying the later principles of jet air combat, and the "corner velocity" principle is too neat and simple for the bunch of prop-driven weirdos that are supposed to fit into it.

    Gaston.