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

[Noir]

I've been reading this post since the beginning (and all the others in this section), but since I don't know much about flying physics I was just trying to learn a bit, and surprised with some of Gaston (lagaffe ?)'s conclusions, especially on the 190 low speed behavior and lately on the spit vs P51 duel issue.

It is well known along AH players that a P51 will get its parts handed by a late war spitfire (spit14 at high alt and spit16 at low alt) in a knife dogfight, the P51 would have to extend kilometres and try to get an energy advantage, which is not easy considering the spitfire climb of rate. It is well known too that a 190 whatever its version has a terrible low speed rate of turn, that compensates its very good high speed handling, especially in dives, making it one of the best "E-fighter" in the game. Both this facts have been accepted for a long time by the AH community, along with some other facts, and that explains why you, Gaston, have met such opposition in your claims on this board I believe.

Gaston, You said you weren't an AH player, but why don't you try the game for a few days, offline (offline use is unlimited) or online and try to compare your conclusions with hitech's ? So this thread, this game and yours get a bit better, cause this is going nowhere ! I'll be happy to fly against or with you, I'm just a gamer that tries to push the envelope of the planes so my view is neutral Buy a cheap Saitek stick but a mouse will do...at first 

[E25280]

Though that 450 ft. turn will certainly turn out to be a misprint or an error by Skychimp (It really does seem not to add up...),  

The radius of the circle would have to be 1345ft at 400MPH TAS to keep the G's in aircraft specifications of 8G's.

450 X 3 = 1350.  SectorNine calculates a nearly equal 1345ft.  450 yard turning circle, not feet.

Misprint or you read it wrong.

[Sincraft]

Excellent stuff Gaston. After reading and then later researching WW2 aerial combat, pilots and airplanes I have certainly found it so true, that the more you think you know, the more you know you don't know. There are so many urban myths and glaring errors in the "general" knowledge about WW2 aviation, as well as little or barely known surprising details under the well known facts. Every new book, every interview always brings new surprising things to think about. Your post gives some very interesting new things to ponder at.

Maybe one day we can stick an aircraft with the engine operating into a wind tunnel with super computers and get exact numbers on abilities, even down to scanning thicknesses of armor ....down to the position of the seating and how many g's a guy could take.  But until then, all we have is speculation and some real world accounts with statistical data.

Some day! 

[Murdr]

Concerning the G, the pilot's manual warns the pilot of a more than DOUBLING of the turn time from 250 MPH TAS to 280 MPH TAS!

I think I see a source of confusion here.  The English translation says "Turning time at speed".  This indicates to me that we are talking about a steady state turn (eg. "sustained turn").  The degrees per second also seems to indicate this is a sustained turn.

The following EM diagram is in a bit different format than the previous ones I posted, and is based on the AH flight model...

If we take the speed figure 250 MPH for the 109G under this configuration, and follow the ps=0 line we find the sustained turn rate is at 12.5 DPS.  The manual figures work out to 13.8 DPS.
If we take the speed 280 MPH, we find the sustained rate of turn is about 9 DPS.  The manual figure works out to 7.1 DPS.  Without knowing the power, weight, and altitude configuration of the manual figures reference, that's not too bad of a correlation.

On the other hand if we look at the maximum rate of turn (at a 6 G limit) we find 29.5 DPS at 250 mph, and just under 26 DPS at 280 mph.

Also note that once both planes are above Cv they are subject to the same G force at max dps for a given speed.  This particular diagram plots data only up to maximum level speed at the given altitude, and only indicates level turns.

My point is that G load at a given speed and rate of turn is a known factor.  Whether we pick an arbitrary 6G sustained unaided pilot limit, or an aircrafts structural limit, the G load at a given speed and dps is going to be the same no matter what type of WWII plane we are talking about. 

So when talking high speed handling, the question is whether an aircraft is capable of achieving a given G load/dps.  Things like a lower critical mach number, high control forces, or lower structural limits can prevent a given aircraft from reaching a given dps at high speed.  The P-51 had relatively good high speed attributes in comparison to it's competition, which leads to it "out turning" planes historically at higher speeds.  But that is an issue of the turn performance of the other plane tailing off because of inherent high speed handling issues, as opposed to the P-51 defying the laws of physics.

[Gaston]

   
     Thanks E25280!

     I think the explanation of a 450 M vs 450 ft. confusion is very plausible, as I was never able to find that IL-2 thread again...

     But a guy expressed scepticism at what HE calculated to be 12 Gs. Also, why the metric/MPH mix? It seems the fault was likely not in my reading...

     The fact I couldn't find it again at the time may mean Skychimp had second thoughts about the source, though it was (claimed)official...

     If true, It does indicate the Spit XIV would be out-turned significantly by a P-51D at 400 MPH TAS, which is very interesting in its own right...

     
     I still have failed to find those 1990s P-47/P-51 tests, but my quote from memory is accurate as to the most relevant part, except that the moderate "peak turn closer than expected to the top level speed" I NOW put in it, MAY have actually been "peak turn quite close to the top level speed" which is a rather stronger statement, and this contributed to my buying the 450 ft./400 MPH radius, since I felt I could not know the amount of mushing involved, and the exact shape of the elongated curves...

     I still think Gs are related to the speed and trajectory only, and that the degrees per second of turn the aircraft's nose actually does may be higher if it spins on itself, which the front-driven prop makes quite possible, and depends on the aircraft type. There are many high speed accounts of P-51s gaining 360° in one turn, mostly against the Me-109Gs, strangely enough, which I think may in part be due to a recurring notion I hear of the 109 not turning well to the right at some speeds. I could not confirm this. It may be related to what follows;

     From the Me-109G-6 pilot's manual, this is my recollection of the huge drop in turn rate at 250-280 MPH TAS (posted by Skychimp in IL-2);


                21 seconds for 360° at 400 km/h. (This high rate indicates a maximum rate of turn to me.)

                27 seconds for 110° at 450 km/h. (This is clearly intended as a warning of a speed-related change.)

     You can see why I speak of a "hole" in the turn rate, and this correlate to an observation by pilot Mark Hanna that is I think very relevant to this "hole";

             "At 400 km/h the nose abruptly drops, like the aircraft wants to get close to the ground, and you have to pull on the stick to catch it. It is a bit unsettling at first, and you learn eventually to trim it in."

           Contrast all of this to the RAF comment; "Surprisingly, the Me-109F can make quite tight turns at 420 MPH TAS."

           Or this P-51D pilot vs 109G-6; "We were stuck in the dive (at 500 MPH+), but to my surprise he pulled out of it first."

           The first comment is another one of those that oversold me on high speed turn radiuses...

           I still think the peak turn rates of the P-47 and P-51 are somewhere above 300 MPH TAS or whatever is generally assumed; it is in the character of these aircrafts that they turned BETTER with speed, though I definitely got carried away with it to say all the way up to 400 MPH TAS...

           I will also moderate my view on the FW-190's poor high speed elevators, but I am still convinced, by numerous Allied pilot anecdotes, that its elevator performance above 400 MPH is nowhere near that of late American fighters or the slower-diving Me-109. In Europe at least, it was in a class of its own in mediocrity, and I am convinced Kurt Tank's impressive high speed dive tests of x Gs per Kilo of stick pull reflected a VERY small time frame, which would correlate well with the always good initial turn-in response of the type.

          The thread about the horizontal stall-fighting FW-190 ace on this very forum would be very useful to dig up, being full of details about different ailerons the pilot could choose, and correlating as it does with the admonition given to Eastern front pilots to NEVER use the vertical against the Western Allies. He describes out-turning a P-51D at speeds of about 300-200 MPH, to the right, using flaps and the powerful ailerons to "catch" the stall, then shooting it down after a full 360° gain in about three or four turns, maybe even two...

          Interestingly, he describes preparing for the fight by REDUCING the throttle before the engagement, to have more reserve power to compensate for the drag of the flaps, and thus not have a decreasing speed in the fight, but one he could MAINTAIN more easily... He describes also the broad wood propeller as a major enhancement, out-accelerating at low altitudes the Me-109G-6, and helping with the stall-fighting.

          Correlating this is the well-known, and VERY detailed, P-47D vs FW-190A-5 test, which shows a great superiority of the 190 in turns up to 250 MPH TAS, then a drastic reversal above that, due I think to a combination of improving P-47 turn vs worsening FW-190 turn. The performance and overheating of the P-47 in climbs indicates full 72" MAP 150 octane use, which usually had to be restricted to 65" MAP in climbs.

          Returning to the 190 ace, I think this active throttle use is less typical of other fighters who don't have the "brainbox" throttle, and use a narrower range of throttle/pitch/mixture adjustments in combat.

          In any case I appreciate the inputs I got here, and WILL fix the relevant aircrafts in my game, though it may take awhile for the fixes to appear on Mike's Air Force Dauntless web site.

          I think calculations have limitations in reflecting reality in these subjects, but at least they can put boundaries on the "facts"...

          I'll be more wary the next time around...

          I hope that despite the errors the info provided was useful.

     Gaston.


       

   

               

     

     

[Murdr]

     From the Me-109G-6 pilot's manual, this is my recollection of the huge drop in turn rate at 250-280 MPH TAS (posted by Skychimp in IL-2);


                21 seconds for 360° at 400 km/h. (This high rate indicates a maximum rate of turn to me.)

                27 seconds for 110° at 450 km/h. (This is clearly intended as a warning of a speed-related change.)

I thought my post made it obvious I had the referenced document and figures in front of me, and not a third hand recollection...

Turning time at speed 400 km/h.  180° ca.  13 s.
     "       "     "     "     450     "     100° ca.  14 s.

Is exactly what it says.

[BnZs]

    The peak turn rate of the P-47 and P-51 cannot be near 400 MPH TAS, but I would still say it is much higher than usually assumed; say 330-350 MPH TAS...

   
   

TAS is not important here, IAS is.

[BnZs]

Both this facts have been accepted for a long time by the AH community, along with some other facts, and that explains why you, Gaston, have met such opposition in your claims on this board I believe.

Or maybe it was the physical impossibilities.

[hitech]

     I still think Gs are related to the speed and trajectory only, and that the degrees per second of turn the aircraft's nose actually does may be higher if it spins on itself

to turn an aircraft it requires G's, basics physics. No other form of turn rates are ever listed.

HiTech

[Noir]

Or maybe it was the physical impossibilities.

well that too, except I wouldn't know 

I still think Gs are related to the speed and trajectory only, and that the degrees per second of turn the aircraft's nose actually does may be higher if it spins on itself

Stalling ?

[Gaston]

   
     Yes Murdr, my recollection was not accurate... What I said amounts to 80 or so seconds per 360, it was more like 50 seconds, from 26 instead of 21, but the basic point I said previously was that it was a vast increase of the turn time, mentioning the correct speeds, which is a huge drop in turn rate for a measly 30 MPH, and that it seems to be related to the nose-down tuck described by Mark Hanna, occuring at the exact same speed.

     I've yet to hear anyone commenting on this peculiar behavior when mentioning the 109G, as though it behaves like any other aircraft at these speeds. Even rarer is the mention of the excellent elevator response when trimmed tail-heavy above 420 MPH TAS, which is backed up by numerous combat anecdotes.

     As far as the elevator response of the FW-190 is concerned, the above-mentioned P-47D tests mentions turning contests, and the pull-out after a detailed dive description; "rapidly INCREASING turn superiority above 250 MPH (for the P-47). Much better elevator response at high dive speeds, with a far superior angle of pull-out (for the P-47)." Plus numerous concurring combat anecdotes as well...

     These points are worth emphasizing, and I didn't see them in AHWiki.


   Gaston.

[Charge]

"These points are worth emphasizing, and I didn't see them in AHWiki."

I think that the reason is that many of those flight tests contain personal impressions of pilots flying an aircraft they are not entirely familiar with and many times there is no measurable data to back up their observations. Some observations are correct but some aren't. Usually only commonly accepted facts are filtered and put to wikis and the relative turning performance between 190 and P47 is not one of them.

-C+

[Murdr]

but the basic point I said previously was that it was a vast increase of the turn time, mentioning the correct speeds, which is a huge drop in turn rate for a measly 30 MPH, and that it seems to be related to the nose-down tuck described by Mark Hanna, occuring at the exact same speed.

Yes, you keep repeating that, and it's obvious you're not going to allow facts to get in the way of your eronious conclusion.

Turning time at speed 400 km/h.  180° ca.  13 s.

This is only about a 2.9 G turn.

    "       "     "     "     450     "     100° ca.  14 s.

This is less than a 2 G turn.

These are not max rate of turn numbers.  

And this does not indicate what you think it does...

Pitch tends to heavy up above 250 mph but it is still easily manageable up to 300 mph and the aircraft is perfectly happy carrying out low-level looping maneuvers from 300 mph and below. Above 300 mph one peculiarity is a slight nose down trim change as you accelerate. This means that running in for an airshow above 300 mph the aeroplane has a slight tucking in sensation - a sort of desire to get down to ground level ! This is easily held on the stick or can be trimmed out but is slightly surprising initially. Maneuvering above 300, two hands can be required for more aggressive performance. EIther that or get on the trimmer to help you. Despite this heavying up it is still quite easy to get at 5G's at these speeds.
~the late Mark Hanna on flying the 109

[moot]

Dang, I sure hope the bit about the Komet wasn't wrong too, that's all I'd really paid attention to out of the first post.

[hitech]

moot

  Me-163B: No emphasis in AHWiki on the fact that the Me-163B climbs FASTER and FASTER as the altitude increases! At 40 000 ft the Me-163B's climb rate is almost DOUBLE what it is at 10 000 ft! This unique feature is due to the decreasing air density that does not affect the non-breathing rocket engine. I have heard the figure that, at this high altitude, the horsepower equivalent is 9000... The Me-163 had a good wingload EMPTY, but the turn performance varied in minutes as burning fuel halved the weight(!). Empty or not, the design had a lazy pitch response, like all tailless designs, but roll was optimized for high altitude and excellent, although it apparently became heavy and lazy at low altitude(this from a well-known P-38 combat account)...

I do not have the specific numbers at hand,so I do not know if doubling is correct, but once again the conclusion is completely incorrect even if the facts are.

Yes air density drops with Alt while thrust does not, but this is the minor factor in the increased climb rate. The big factor is simply burring most of its weight in fuel while maintaining a constant thrust. The fuel burn rate is so high, that computing and documenting climb performance becomes problematic.

So when statements like

At 40 000 ft the Me-163B's climb rate is almost DOUBLE what it is at 10 000 ft!

are made , they are completely misleading. Because what is really meant is that the 163 climbs twice as fast at 1/2 the weight, to which most people would say "Well Duahhh"

HiTech