RHS Maneuverability Review: Data [ALL Data Done]

[el cid again]

Herwin: You may be helping. You may, for example, have come up with a justification for doubling the 4 engine divide by factor.

How can roll rate be "gestimated" in any consistent and relatively accurate sense?

[el cid again]

ORIGINAL: Nicholas Bell

    El Cid-

Don't forget to run the tests for yourself if you don't beleive me.  Bomber manueverability has no impact on combat resolution.  Cruise speed does.  Just set the the values to zero in a test run and you'll see.

This does not appear to be correct. First of all, we have an official Matrix statement that maneuverability is the primary factor in air combat. Second, we have two different test beds (at least) using stock, CHS and RHS data, that seem to indicate otherwise.

Note, however, that test results are very hard to interpret without vast numbers of test runs, UNLESS you have the ability to control the "seed."
Matrix code does NOT duplicate the "identical" run each time - but generates a completely different random number each pass - even from the same starting point. ONLY a very unusual editor PLUS knowledge of where the seed it, used on each pass, permits accurate testing. This long confused me - until someone who does run such "fixed" tests - advised me. I do not doubt that everyone suffers from test result confusion as much as I did if they are not addressing this factor. There are likely other factors equally as obscure.

[Mike Scholl]

ORIGINAL: herwin

ORIGINAL: Terminus
The effect of having two engines rather than one is to decrease the maximum roll rate and (usually) to increase weight (relatively speaking). You end up with decreased roll rate (due to the weight of the engines out on the wings), decreased sustained climb and operating altitude (from the reduced power to weight ratio), increased dive speed (because your CD was reduced), decreased maximum speed (more parasitic drag and less power to weight), decreased power to weight (meaning you couldn't accelerate as fast), and reduced turn rate (due to increased wing loading). The only one of these that you can't estimate from the published parameters is roll rate, which you can guestimate.

Don't quite understant the "power-to-weight" portion. A single engine has to power it's own weight and that of the entire airframe. Twin engines have to power their own weight, but only half that of the airframe. Power-to-weight would be particular to the individual design. The Mosquito had a quite high power-to-weight ratio (and speed), while the C-47's was fairly low (especially when you add in cargo). I don't see this portion of your data as being valid. Too much dependent on the individual design.

[el cid again]

It does not matter - because power to weight is a strict function.
Mike is correct - a 2E plane may have a very low power to weight value - and transports in particular generally do. It may also be very high - and something like a P-38 must be in that range. But a function which divides weight by power is going to work out the actual value - regardless of what it is. I think the quoted comments were meant to refer to a restricted data set involving only fighter type planes. Even so, it would surely depend on the exact power and weight - any such generality even if true would have theoretical and probably actual exceptions. But since we are dealing with functions, they will produce values exactly proportional to the values we plug in - so each plane gets its due - as it were. What we are trying to do is figure out a better function - and the problem I think lies in the "divide by number of engines" part - in spite of the fact that probably is a valid factor. Ideally we would just look at pure performance statistics - speed - ROC - loading - name it - and ignore configuration altogether. But it does not appear that is quite valid; configuration seems to matter. P-38 is fabulous - but it is not as good as a single engine plane of the same statistics would be - in terms of maneuverability - while it is somewhat more likely to survive if it suffers fatal engine damage. A 4E plane that had the same statistics as a P-38 would still not be as manueverabilt - but it woul be even more survivable if an engine were hit. [I would prefer to be wrong about this too: just using performance data would be a cleaner function - if only it were also an accurate model]

[herwin]

Remember this post? WWII Air Combat Model

That should give you some insight into your questions.

[herwin]

ORIGINAL: el cid again

Herwin: You may be helping. You may, for example, have come up with a justification for doubling the 4 engine divide by factor.

How can roll rate be "gestimated" in any consistent and relatively accurate sense?

It gets rather complicated. Since turns and rolls involve the same forces, a plane that flips into a turn quickly does so because it rolls quickly. A roll is produced by deflecting the ailerons (involving muscle power in earlier and lighter aircraft), and adjusting the tail surfaces for control. You're generating angular motion around the forward axis of flight, so you have to overcome angular momentum. Two and four engined aircraft have much larger angular momenta, both due to sheer mass and the engines out on the wings, so roll acceleration is slower. In-line engines spin the crankshaft, while radial and rotary engines spin the engine, so they possess more angular momentum in a specific direction to start with--this is the reason your roll acceleration is different in the two directions of roll with radial/rotary engine fighters.

I had to model this stuff for my PhD thesis, but I was concerned with bat aerodynamics. Bats are not little aircraft--they can do impressive things with their wings that even birds can't.

I suspect you can find maximum roll rates and roll accelerations in the technical data for some typical WWII planes. Extrapolate from there.

One other thing--maximum sustained angular rate of turn takes place at a moderate speed. This is because it involves a combination of lift to remain airborne and lift to turn. The fast the aircraft flies, the more lift is available to turn, but the power requirements to maintain a given angular rate go up even faster. The Zero had muscle-powered control surfaces, so it became hard to control at high speed.

[herwin]

ORIGINAL: Mike Scholl

ORIGINAL: herwin

ORIGINAL: Terminus
The effect of having two engines rather than one is to decrease the maximum roll rate and (usually) to increase weight (relatively speaking). You end up with decreased roll rate (due to the weight of the engines out on the wings), decreased sustained climb and operating altitude (from the reduced power to weight ratio), increased dive speed (because your CD was reduced), decreased maximum speed (more parasitic drag and less power to weight), decreased power to weight (meaning you couldn't accelerate as fast), and reduced turn rate (due to increased wing loading). The only one of these that you can't estimate from the published parameters is roll rate, which you can guestimate.

Don't quite understant the "power-to-weight" portion. A single engine has to power it's own weight and that of the entire airframe. Twin engines have to power their own weight, but only half that of the airframe. Power-to-weight would be particular to the individual design. The Mosquito had a quite high power-to-weight ratio (and speed), while the C-47's was fairly low (especially when you add in cargo). I don't see this portion of your data as being valid. Too much dependent on the individual design.

Bigger airframe. The highest power to weight ratios were for small single-engined interceptor fighters.

[el cid again]

Regretfully, finding roll data for a few planes, and "extrapolating from there" is not going to work. It violates CHS/RHS standards for data - and it is probably not going to be valid either. Different manufacturers don't do things the same way, and some radical planes (J7W comes to mind) probably are very different in how they behave than anything we would be looking at. [There is a tiny plane in Anchorage of similar configuration - and it is almost impossible to describe how it can fly - you have to fly it to begin to understand the impact of a canard]. If we cannot come up with a theoretically valid way to determine roll rate from data that is available, we cannot use it. I think arguments would be endless if we tried to estimate this value - and there would be no rational way to settle them either. People would be sure I was a JFB or an AFB if their pet plane was not better than others.

[herwin]

ORIGINAL: el cid again

Regretfully, finding roll data for a few planes, and "extrapolating from there" is not going to work. It violates CHS/RHS standards for data - and it is probably not going to be valid either. Different manufacturers don't do things the same way, and some radical planes (J7W comes to mind) probably are very different in how they behave than anything we would be looking at. [There is a tiny plane in Anchorage of similar configuration - and it is almost impossible to describe how it can fly - you have to fly it to begin to understand the impact of a canard]. If we cannot come up with a theoretically valid way to determine roll rate from data that is available, we cannot use it. I think arguments would be endless if we tried to estimate this value - and there would be no rational way to settle them either. People would be sure I was a JFB or an AFB if their pet plane was not better than others.

Oh, God... All those books are in America. Roll rate involves angular momentum, so high aspect ratio wings are bad and engines on the wings are bad.

"At 160 mph (260 km/h), A6M2 had a roll rate of 56 degrees per second." (from Wikipedia)

Spitfire I roll rate was 140 deg/sec. (http://www.aviation-history.com/)

P47D: 85 degrees per second.

P47N: 100

P38--a slow roller until the L model.

See also Roll Rates

For interesting figures see some guesstimates, it appears.

The first six below are from Perkins and Hage and are reliable.

P-47: 71 at 250 knots (per guesstimates, F6F, F4F, SBD, P-39D, Ki84, A6M3, and A6M5 similar, FM2 about 90)
P-38: 78 at 257 knots
P-51B: 98 at 260 knots
P-40: 134 at 314 knots
Spitfire V: 150 at 176 knots
FW-190: 151 at 226 knots

More guesstimates.
TBF: about 40 at 250 knots
F4U about 120
A6M2 about 50
Ki43 about 55
Bf109 about 85-90
Bf110C about 45
Spitfire V and Hurricane about 85-90
I don't believe the early P38 figures as it was comparable with the Bf110.
D3A and B5N about 33
B25H about 36
B17G about 10

The helix angle (pb/2V) is a constant times the airspeed up to the point that the ailerons start to flex or are too stiff to move. (p is the roll rate in radians per second, is the airspeed in feet per second, and b is the wing span in feet) The minimum acceptable value for the helix angle was about 0.07 for bombardment and transport aircraft and 0.09 for fighters in WWII. Source. About 125 degrees per second at 250 knots corresponds to 0.09 for a 30 foot wingspan, which means most WWII fighters were deficient.

You might find the following interesting: NASA history of aircraft

[Herrbear]

ORIGINAL: el cid again

ORIGINAL: Mifune

Cid, just so I can understand. On your current proposal, how would your formula look?

[ (Speed / 20) + (ROC/250) + (Wing Loading/x) + (Power Loading/y)]

all divided by Square Root (Number of Engines)

Exception 1: Two engines on the same axis count as one.
Exception 2: 3 + engine planes double the denominator.

Where x and y are values not yet determined so that the loadings will end up in the indicated range.

When determining the power load for a 2 engine plane would it be the weight/2xengine horsepower? For example, if a 2 engine plane had 2 1000hp engines and weighed 26000, would the power load be 26000/2000 = 13 lbs/hp?


Also, isn't the more manueverable plane the one with the lower power load figure? So if you were adding power load into the equation, how do you account for lower is better?

Thanks Sid.

[el cid again]

Wikipedia is a book?

A wiki is a group - anyone can put in anything. Wikipedia is just the biggest wiki of all time. It is a most dangerous source and never to be trusted unless you validate what you read. And I have no data on the roll rate of a Zero - not even though I have half a dozen books dedicated to it - including one on the first we ever got to examine - complete with the technical report done on it. While I do not doubt we can get roll data for some Zero - there is one at Tillimook we might test if need be - the problem remains: we need a consistent and scholarly source for ALL planes, or failing that, a way to calculate it from data in the standard sources which is sound and can be shown to work. I do not believe there is any single consistent source of this data - the ideal case - nor even a combination of sources - the fall back case. And I would love to be pointed at such materials. I pretty much have the standard materials related to aircraft - more than a major library does - and I am not aware of where to find this data. But a wiki? Not only will you not find this data for most planes in it, you cannot know if the data is any good without finding it in a better place. If you could do that - just use the better place and be done with it.

[el cid again]

Yes Herrbear

You got power loading right as far as calculating it goes

it is total weight / total power

But no, lower power loading is not more maneuverable. Rather more power = more maneuverable. The real dogs of the air have horrible power to weight ratings.

You may be mixing this up with wing loading. Lower wing loading is better for maneuverability.

[herwin]

OK, here's a formula:

The log2(exchange rate) = -0.86*log2(wing loading) + 0.53*log2(power loading) + 0.28*(maximum speed)/10 +
0.38*log2(initial rate of climb) + 0.5*(number of combats survived up to eight) + C.

I didn't include roll rate in the 1976 analysis, although you could roll out of a combat with a Zero. Try this: figure out the resulting ratings for a F4F and an A6M2, and then estimate the coefficient that when multiplied by the log2(roll rate at 200-250 knots) equalises the two. I suspect it will be on the order of +0.5.

By the way, C is an arbitrary constant.

[el cid again]

Regretfully, we can't use a formula with "number of combats survived"
(or "number of combats" of any sort) because we must enter a single value for the airframe - regardless of the experiene of the pilot! Pilot experience is a different function - and IS present in WITP - but not in the maneuverability rating of the airframe.

I have begun to see that the issue of roll overcoming angular momentum is a justification for the formula we presently use. To the extent that roll rate matters, multi-engine planes don't do it. Our formula gives them credit for their speed and ROC - but penalizes them for (in effect) poor roll rates - by making the penalty inversely proportional to the number of engines.

Now the formula Herwin proposes above is very interesting - but attributes far too little of the rating to speed. The WITP code may originally have expected purely speed for maneuverability (one programmer guessed that was the case - and some of the data supports the theory in the form of speed/10). It appears later to have included ROC - and possibly other factors (in particular double wings on biplanes).
Now speed and ROC really do matter a lot - so much that the Japanese insistence on extreme "maneuverability" in the sense we usually think of it was not as important as faster and fater climbing planes - at least eventually (when we figured out a thing or two). To the extent we modify our rating in favor of planes with less wing loading (etc), we are going to make things like Ki-27 and A5M4 (and Zero) look better. And we are going to make F3Fs and F4Fs and many P-xx planes look worse. I am not sure this is really the intent the critics of the rating system have in mind. Worse, we may find P-38 fares worse as well.

Running the numbers a variety of different ways produces this remarkable conclusion: one can do a lot of math to come to very similar results with what we have right now. I DO think that biplanes are not well represented in the RHS formula - and wing loading will help address that - but I suspect that power loading is more or less going to be very similar (relatively speaking) to ROC values. So increasing the non-speed part of the function is likely to benefit biplanes to a degree, and all fighters vs dogs (in terms of ROC and power loading). That may be exactly what we want to do - for relative to true bombers and transports - P-38 (and other 2E fighters) are going to look better. But they really are not going to look better relative to Zeros and other 1E planes - and in fact worse compared to a Pete - which I fear may be both accurate and unpopular.
P-38s could not really dog fight with Zeros very well - and were much better advised to dive on them from above - gaining still more speed in the dive - and not attempting to continue the fight after the firing pass.
Zeros in particular were not very good at diving, had no armor to protect against hits, making any guns (and guns in numbers on US planes) always effective. If something went wrong, the P-38 had armor - and the Zero's only rapid fire guns were .30 cals - which the armor often could stop. It may be a problem in the WITP air model is that players cannot specify any sort of tactics (other than altitude). This forces a P-38 into an extended combat it may not be wise to engage in. On the other hand, given its armor - and ability to go home after losing an engine on occasion - it may be that extended combats actually hurt Zeros even more? Testing will tell.

Oh - for testing - run the test bed through turn one BEFORE saving it for test use. That way you get a common seed for all tests. A new seed is generated on turn 1 - but the Japanese "player" always starts with the same seed on every turn after turn 1. [That is, in any particular game, the seed is handed on from turn to turn, and you can restart a turn and get the same results because the same turn will always start with the same seed]. This way, test results are not affected by different random number seeds. [There are enough variables to worry about without that to confuse things]

[herwin]

ORIGINAL: el cid again

Regretfully, we can't use a formula with "number of combats survived"

Then ignore it.

(or "number of combats" of any sort) because we must enter a single value for the airframe - regardless of the experiene of the pilot! Pilot experience is a different function - and IS present in WITP - but not in the maneuverability rating of the airframe.

I have begun to see that the issue of roll overcoming angular momentum is a justification for the formula we presently use. To the extent that roll rate matters, multi-engine planes don't do it. Our formula gives them credit for their speed and ROC - but penalizes them for (in effect) poor roll rates - by making the penalty inversely proportional to the number of engines.

Now the formula Herwin proposes above is very interesting - but attributes far too little of the rating to speed. The WITP code may originally have expected purely speed for maneuverability (one programmer guessed that was the case - and some of the data supports the theory in the form of speed/10). It appears later to have included ROC - and possibly other factors (in particular double wings on biplanes).

Actually, the value of speed is quite high in the formula. You get +1 for about a 30 knot increment, and you can't get a lot of increments for the other elements.

Now speed and ROC really do matter a lot - so much that the Japanese insistence on extreme "maneuverability" in the sense we usually think of it was not as important as faster and fater climbing planes - at least eventually (when we figured out a thing or two). To the extent we modify our rating in favor of planes with less wing loading (etc), we are going to make things like Ki-27 and A5M4 (and Zero) look better. And we are going to make F3Fs and F4Fs and many P-xx planes look worse. I am not sure this is really the intent the critics of the rating system have in mind. Worse, we may find P-38 fares worse as well.

Running the numbers a variety of different ways produces this remarkable conclusion: one can do a lot of math to come to very similar results with what we have right now. I DO think that biplanes are not well represented in the RHS formula - and wing loading will help address that - but I suspect that power loading is more or less going to be very similar (relatively speaking) to ROC values. So increasing the non-speed part of the function is likely to benefit biplanes to a degree, and all fighters vs dogs (in terms of ROC and power loading). That may be exactly what we want to do - for relative to true bombers and transports - P-38 (and other 2E fighters) are going to look better. But they really are not going to look better relative to Zeros and other 1E planes - and in fact worse compared to a Pete - which I fear may be both accurate and unpopular.
P-38s could not really dog fight with Zeros very well - and were much better advised to dive on them from above - gaining still more speed in the dive - and not attempting to continue the fight after the firing pass.
Zeros in particular were not very good at diving, had no armor to protect against hits, making any guns (and guns in numbers on US planes) always effective. If something went wrong, the P-38 had armor - and the Zero's only rapid fire guns were .30 cals - which the armor often could stop. It may be a problem in the WITP air model is that players cannot specify any sort of tactics (other than altitude). This forces a P-38 into an extended combat it may not be wise to engage in. On the other hand, given its armor - and ability to go home after losing an engine on occasion - it may be that extended combats actually hurt Zeros even more? Testing will tell.

Oh - for testing - run the test bed through turn one BEFORE saving it for test use. That way you get a common seed for all tests. A new seed is generated on turn 1 - but the Japanese "player" always starts with the same seed on every turn after turn 1. [That is, in any particular game, the seed is handed on from turn to turn, and you can restart a turn and get the same results because the same turn will always start with the same seed]. This way, test results are not affected by different random number seeds. [There are enough variables to worry about without that to confuse things]

[el cid again]

I will play with it.

[Mike Scholl]

Some "ramdom thoughts" from a non-aironautical engineer.

SPEED Seems to be the biggest determining factor of wether or not there will even be combat. The side with a significant advantage in speed (or altitude, which can be "traded" for speed) gets to choose IF there will be combat, and under what set of perameters it will take place.

MANUEVERABILITY Roll rate, climb rate, turn rate, wing loading, and all this other "nifty stuff" comes into play once combat is actually joined and helps determine who gets a shot at who and when and how often. But the faster and higher side determines which of these factors will be the most useful when it initiates the combat. Less of a "factor" when dealing with bomber formations, because they aren't trying to manuever anyway, but trying to bring enough of the 3rd factor into play to discourage/destroy the attacker.

FIREPOWER How much "effect" can you put "on target" and how quickly? Obviously more is generally better, until it's weight begins to effect the Manueverability and Speed factors, because a shorter "burst" is more likely to inflict damage.

DURABILITY How much "punishment" can the airframe absorb "on average"? Obviously, a single bullet to the head of the pilot will bring down most A/C, unless they have larger crews and a co-pilot ready to take the controls. But for a "formula" to work, we have to achieve an "average amount of damage recieved" consensus concerning each airframe's vulnerability. The amount at which it "might still survive"; or "might have gone down already" are relatively equal. Armor, structural strength, radial engines, and other things effect this, as well as sheer size.

(PILOT SKILL is the "kicker" and can equalize a number of the factors above. Fortunately for this discussion it's a different formula.)

So all that is necessary is to juggle the four factors above into a usable set of formulas. Go to it! (Does make it obvious why the Japanese were generally "hurting" through much of the war. The allied A/C were generally faster, so they could choose attacks that utilized their own particular advantages in "manueverability". In Firepower they were at least equal or better in most cases, and in Durability almost always superior. When Japanese pilot skill began to deteriorate, while Allied improved, they were really caught between "a rock and a hard place". No wonder Kamikaze tactics appealed to them - by 1944-45 any mission they flew had a "suicidal" factor to it, so you might as well "go for the gusto" and do it officially.)

[Nicholas Bell]

Mike, you're random thoughts are spot on.  El Cid & Herwin, your desire to mathematically calculate manueverability values is commendable.

Hate to be pessimistic, but it's all meaningless in game terms because the air combat formula is broken, nerfed, borked or what ever you want to call.  No matter how good the data is, it's going to spit out junk.  It's just a numbers game - who's got more planes - with the differentials between manueverability and speed, etc modifying this. 

Please try setting the all the aircraft values to 0 and see what happens.  Then set them all to 10.  Then try speed at 0 and manueverbility at 30.  Ensure all pilots are set at the same experience level (99).

Understand better how the engine works (or doesn't) first, then consider how to standardize the values, is what I am saying.  I've wasted too many hours playing with the values attempting to find some basis to work from for at least somewhat historical results.  What you do with your time is of course your business, but I hate to see you spend so much effort on something which will have so little results.

[Nicholas Bell]

Oh let me add this for your consideration of how hopeless this is:  Aircraft do not need weapons to shoot each other down.  Remove all devices from aircraft and casualties are just as bad as ever.  Try it yourself if you don't believe me.

[Mike Scholl]

ORIGINAL: Nicholas Bell

Oh let me add this for your consideration of how hopeless this is:  Aircraft do not need weapons to shoot each other down.  Remove all devices from aircraft and casualties are just as bad as ever.  Try it yourself if you don't believe me.

WOW! Talk about DEPRESSING.... And you've tested this?