RHS Maneuverability Review: Data [ALL Data Done]

[el cid again]

ORIGINAL: witpqs

Sid,

I understand your answer to other folks' questions here, but mine still stands. Should the P-38 be rated that much lower in maneuverability? It's the degree that I'm concerned about. I fully understand angular momentum - that's why I initially said I understand an off-axis two-engine fighter will be inherently less maneuverable than a single engine fighter.

BTW I agree with rating bomber 'night-fighters' the same as the bomber. I just asking about a purpose built high-performance machine.

Well - maybe not.

This thread is my THIRD try to change the differential - in favor of the P-38 - in response to Rev's complaints about it.

Note that I ALREADY changed this relative differential once - and the proposed new standard moves father in that direction. Further note that the relative difference between dogs with many engines and P-38 is getting wider. That is the most we will ever be able to do: maybe we can make it better - but it is just a question of degree - not an absolute thing.

There is one thing I think may not have been done as I specified - and if that is so the present formula may work a little better (giving us about 1 more point in differential) - but I need to check that. I am trying to do this better.
I am not trying to please P-38 people - just get it relatively right compared to other things. P-38 is never going to rival a F4U-4 in maneuverablity - or a Nate for that matter. Those who think otherwise are never going to be happy with any reasonable formula. And frankly I will never be happy until I have

a) At least three different altitude maneuver factors
b) separate horizontal from vertical maneuver factors

But that is not an option in this version of WITP.

[el cid again]

ORIGINAL: Herrbear

ORIGINAL: el cid again

ORIGINAL: Herrbear


Thanks for your answer. I certainly understand your "c" and now El Cid is taking into account of WL and PL in his formula. His formula causes 2-engine fighters to be almost 1/2 as manueverable as a single engine figther. In your estimation, would your "a" and "b" cause that much deviation?

There needs to be some way to determine the effects of engines. This must apply not just to fighters, but to fighter bombers, bombers and transports. It may be there is a better system. In stock and CHS they DOUBLE the number of engines for heavy bombers: that is they divide by 8!!! They use EXACTLY the number of engines for two engine bombers: that is they divide by 2 - and the same for two engine transports. [Lacking 4 engine transports in stock and CHS I cannot say what they do in that case?] But RHS HAS 4 engine transports - and it is hard to see how an LB-30/C-87 is much different from its B-24 parent? So I choose to treat them the same. Similarly, I fail to see how taking a Ventura bomber and making it a night fighter makes it more maneuverable? So I treat them the same. I will consider a different factor - propose one. But remember it must work for ALL cases - not just one plane or one plane type.
I have tried square root of number of engines - and the impact on 4 E planes is not acceptable.

But should all 2-engine planes be treated the same? Are not planes designed to intercept built and shaped differently than a 2-engine type medium bomber. Certainly speed, ROC, PL and WL play a part and all 2-engine designs apparently are less manueverable than a single engine, but is a 2-engine fitghter and a 2-engine bomber with the same characteristics handle the same?

To the degree they are better, fighters need to PERFORM better: this must show up as speed, ROC, wing loading, something. We are MEASURING what they really do - and if it isn't better - it isn't. I do not get emotional about numbers - I am a scientist - they are what they are. Yes - treat all 2 engine planes exactly the same - and give advantages to those that are faster or whatever.

[el cid again]

ORIGINAL: Herrbear

ORIGINAL: witpqs

ORIGINAL: Herrbear

But should all 2-engine planes be treated the same? Are not planes designed to intercept built and shaped differently than a 2-engine type medium bomber. Certainly speed, ROC, PL and WL play a part and all 2-engine designs apparently are less manueverable than a single engine, but is a 2-engine fitghter and a 2-engine bomber with the same characteristics handle the same?

I believe Sid is agreeing with you. he has noted that planes that are really bombers that have been drafted into the role of night-fighters are being treated like the bomber version.

Yes that is true, but I think he is treating all 2-engine planes the same.

You are both right. And I do treat them all the same - EXCEPT for classification - and THAT matters to code.
But you are not going to see that difference in this field. So it IS going to turn out different in combat - and it is NOT in this field. Understand?

[herwin]

ORIGINAL: Herrbear

ORIGINAL: herwin

ORIGINAL: Herrbear




I can understand your rationale regarding 2-engine fighter types before the use of PL and WL. By using these in the calculation, are you sure that you are not penalizing 2-engine fighter types twice? If not, what is inherently unmanueverable about them when combining speed, ROC, PL and WL? I understand reduction added to 4-engine planes as they were not built to withstand excessive G forces. This would impact many 2-engine bombers as well. Are you also saying that 2-engine planes designed as interceptors could not handle the G forces that a single engine plane could?

Three-part answer:

a. Twin-engined fighters can't roll as fast. Hence they can't go into a turn as fast.

b. Twin-engined fighters have to deal with higher stresses, potentially limiting the Gs they can pull.

c. Twin-engined fighters tend to have higher wing-loadings and lower power-loadings, reducing their maneuverability.

Thanks for your answer. I certainly understand your "c" and now El Cid is taking into account of WL and PL in his formula. His formula causes 2-engine fighters to be almost 1/2 as manueverable as a single engine figther. In your estimation, would your "a" and "b" cause that much deviation?

The slow rate of roll reflects the larger angular momentum of an airplane with engines out on the wings. That also produces the larger stresses, since larger aileron forces are needed to produce a given roll rate or maintain a given roll angle. Those two factors could easily result in reduced maneuverability.

[el cid again]

Looks like my specifications for the new formula were not entirely followed, so we should see a somewhat greater difference in the data than we see above. What we are doing is increasing the relative importance of loading at the expense of speed - and leaving ROC in the same proportions - which should benefit a hot two engine plane. The correct formula already ran for the P-38 - and it picks up another point.

[Herrbear]

ORIGINAL: el cid again

Looks like my specifications for the new formula were not entirely followed, so we should see a somewhat greater difference in the data than we see above. What we are doing is increasing the relative importance of loading at the expense of speed - and leaving ROC in the same proportions - which should benefit a hot two engine plane. The correct formula already ran for the P-38 - and it picks up another point.

Can you publish the revised formula?

[el cid again]

ORIGINAL: Herrbear

ORIGINAL: el cid again

Looks like my specifications for the new formula were not entirely followed, so we should see a somewhat greater difference in the data than we see above. What we are doing is increasing the relative importance of loading at the expense of speed - and leaving ROC in the same proportions - which should benefit a hot two engine plane. The correct formula already ran for the P-38 - and it picks up another point.

Can you publish the revised formula?
[/quote

We are still tampering with the formula to insure the correct result range. We want to avoid lots of high ratings - as a way to keep air combat losses down. 36 seems to be a majic number and if possible I do not want to approach it.
Doing this has worked for RHS so far. We want 4E planes in the 3-5 range with 4 as a norm. We want 2 E bombers and transports running around 6-10 and 2 E night fighters and fighters running in the 8-16 area. We want 1 E planes running all the way from about 6 to about 32, depending on if they are real dogs or hot, with 26 a really good early rating for a fighter plane. This is slightly compressed from stock and CHS in terms of the absolute range - because we don't like the effects of very big numbers - and because you cannot differentiate between a fair preforming 4E plane (a B-17) and a dog (an Me-264) if you use values like 1 and 2 (they will all be the same). The formula is approximately:

speed / 30 it used to be speed / 20 and it is maximum speed in mph (I would prefer knots)

ROC / 500 this is INITIAL ROC - the point where it is most different - allowing hot planes to
show off their stuff

Wing Loading with a K this factor must be inverted - as loading goes up manuverability goes down

Power loading with a K this factor must actually be divided into a K factor

Number of engines This factor is used to divide the sum of the other factors - and it appears to be
the proper way to treat engines pending a better mechanism to measure the impact
of conservation of angular momentum for different structures. It meets the WITP
criteria of being simple and remarkably accurate - in spite of its unpopularity.

[el cid again]

We have a very satisfactory new formula -

BUT it makes 2 engine fighters - and P-38 in particular - WORSE than they are now
for maneuverability.

We find that the high fraction we give speed BENEFITS these planes relative to
wing loading - which hurts them - they are not good at it.

The new system is very nice - but I fear a firestorm if P-38 actually goes down!
And for the record this review was not intended to have that effect.

Comments please.

[witpqs]

Well, as many others who are interested in this mod I am interested in an accurate portrayal. I don't really care about formulas in and of themselves, but obviously they help tremendously with the unimaginable burden to the modder.

Another poster mentioned somewhere above that the most practical route might turn out to be using a formula for the bulk of cases and a bit o' witchcraft and black magic (or words to that effect) for certain cases that defy the formula.

I think we may have arrived at that point. The P-38 seems to be such a case, there might be a very small handful of others (the fewer the better). I do not know exactly what value the P-38 should have, that must be left to others with more data and more knowledge. I know that it was pretty darn good, but that state of the art (and even near state of the art) single-engine fighters of the day were definately more maneuverable. The P-38 had other attributes that helped to compensate.

Also, as I mentioned in a post earlier, the comparison in maneuverability between the P-47 and the P-51 might also benefit from adjusting (to make the comparison more accurate). It's my understanding that the P-51 was more manueverable, while 'The Jug' was more durable.

This brings up another point - does the durability formula consider radial versus in-line engines?

[akdreemer]

ORIGINAL: el cid again

We have a very satisfactory new formula -

BUT it makes 2 engine fighters - and P-38 in particular - WORSE than they are now
for maneuverability.

We find that the high fraction we give speed BENEFITS these planes relative to
wing loading - which hurts them - they are not good at it.

The new system is very nice - but I fear a firestorm if P-38 actually goes down!
And for the record this review was not intended to have that effect.

Comments please.

This would be true in all P-38 models up to the late model J and the L's. Here is a good case of needing to examine what was different: primarily power assisted airelons. All previous P-38's rolled poorly. In a straight up dogfight at speeds over 200kts the P-38L could outroll most fighters. Over 300kts none could roll as fast. Here I am discussing a specific exception to the multiengine rule. Conservation of Angular Motion is only one part of the overall forces effecting roll rate. Single engined aircraft typically rolled worse in the direction opposite of engine torque, as engine torque acts to inrease angular motion in that direction. Conservation of Angular Motion is the primary law of motion only in a closed system. Anything other than a closed system other forces need to be considered.

[el cid again]

Durability - defined by me for CHS at a time I was supervised by Joe Wilkerson - a mathmetician and programmer -
uses a number of factors, including

the sheer size of the aircraft (actually square root of the empty equipped weight in pounds divided by 1000)

the number of engines

the number of pilots

the construction of the aircraft itself - including non-metal, partial metal (including just control surfaces of fabric in this category), all metal - and special case (e.g. the geodesic construction of a British bomber, the peculiar cast forward
structure of the Sturmovik, etc)

and the existence of armor (with a very small number of special cases that might be called "extra armor")

There is no consideration of engine type - and not much interest in my part in trying to figure out the engine type
for 249 types of planes. It is probably a monumental task - and not very practical - and in more than a few cases there is more than one kind of engine! We are likely not to know the type for a number of planes.

[el cid again]

We have some new data - although I am not sure how we got it? By playing with constants we get:

I am a bit tired, but I wanted to run these numbers by you. I like how
this set came out, let me know what you think. A6M2=28, P-38J=16,
Ki-84=32, F4U-4=40, Spitfire VIII=33, B-24D=4, A5M4=26, P-40E=26,
P-51B=33, Ki-45KAIc=14, J2M2=34


This looks outstanding to me - meeting all my criteria.

[witpqs]

Given AW's statement, should there be a modifier for the rare cases (or case) where the aircraft was equipped with power aerilons?

[el cid again]

REPLY TO my own "I don't know how we got it:" What he did was increase the absolute value of ROC by 250% while following my instructions todecrease speed by 33% and adding both types of loading. This isn't quite what I thought of - but it may be better than my proposal (which was leave ROC alone). ROC is a great way to distinguish
between a dog twin engine transport or bomber, a moderate twin engine night fighter or fighter bomber,
and a hot twin engine fighter (e.g. F7F, Ki-102 or P-38). The system is remarkably good and meets my
overall perameter limits (4 for a normal 4 engine plane, 3 the absolute dog bottom, 5 for a good performing
4 E plane - so you can tell them from each other; just over 30 for a hot 1 E fighter - so we avoid the code
kill rates at 36 and above; 2 E planes spread out from dogs at 6 to hot at 16).

REPLY TO WITPQS: To this we might add a special case - along the lines of what we do for the Sterling or the Sturmovik in the case of durability - for cause - for the P-38 L. IF the powered alerons matter above 200 knots,
we must give it to all planes. But even if they matter - a dog fight forces loss of energy, altitude and speed on
all participants - so this plane is still at a disadvantage if the f ight goes on - and speed goes down; I don't want
to rate it equal to a 1E plane. The question is: what is the special case effect? Add a point or two to the
maneuverability? Or multiply it times 1.5? Or something else?

AND we need to look for ANY other case of powered alerons. On BOTH sides. IF we adopt a special case.

Note there is a special case not used: A Ki-62 - or a German Pfiel - or a B-34 (I think) - would be rated as one engine planes because the engines have one axis on the centerline.

[Mifune]

"German Pfiel - or a B-34" I believe you mean the Do-335

[witpqs]

ORIGINAL: el cid again

I don't want to rate it equal to a 1E plane.

Agreed.

The question is: what is the special case effect? Add a point or two to the
maneuverability? Or multiply it times 1.5? Or something else?

I am hoping there is someone out there on the forum who knows enough about the maneuverability of the P-38 versus one of the single engine fighters to give us a comparison. Like "It's a little less than this one" or "It's about equal to that one" or something along those lines. I would be guessing.

If I have to be the one to take a guess, I am willing to do it. I am just hoping someone who knows more than I do can take a swag.

[ChezDaJez]

I am hoping there is someone out there on the forum who knows enough about the maneuverability of the P-38 versus one of the single engine fighters to give us a comparison. Like "It's a little less than this one" or "It's about equal to that one" or something along those lines. I would be guessing.

This is from http://www.spitfireperformance.com. It has several P-38 performance tests for the P-38G-L models that were conducted in 1943 and 1944 by the USAAF at Wright Field and in Florida. Here is an excerpt:

Flight Tests on the Lockheed
P-38J Airplane, AAF NO. 43-28392
Using 44-1 Fuel
I Introduction

Flight test have been conducted at Wright Field on the P-38J-15 Airplane, AAF, No. 28392 at the request of the Power Plant Laboratory, Engineering Division. These tests were made to determine the increased performance of the airplane using the higher powers allowable by the use of 44-1 fuel as compared with the powers allowable with the standard fuel, grade 100/130, Spec AN-F-28. From 6 April to 24 June 1944 approximately 30 hours were flown on the airplane by Major F. A. Borsodi, Major G. E. Lundquiest, Captain Z. D. Fountain, Jr., Captain E. W. Lesch, and Captain J. D. Onerem. Approximately 18 hours were flown on the original engines, the remainder with a new right engine.

II Summary

The P-38J-15 is a twin-engine, high altitude interceptor-fighter. The airplane performs well at high altitude, having a good maneuverability and radius of turn when using maneuvering flaps. The rate of roll is fair at medium speeds and slow at high speeds because of high aileron forces. This is improved in later models by the use of aileron boost.

Unfortunately it doesn't have much data on the L model beyond speed trials at various altitudes. The site does contain performance tests and charts for the P-51 and P-47 plus all variants of Spitfires. It is mainly oriented towards the European theater in aircraft comparisons.

Anyways, read through it and see if it helps.

Chez

[witpqs]

This might answer all your questions... [;)]

[witpqs]

ORIGINAL: ChezDaJez

Anyways, read through it and see if it helps.

Chez

Great site - thanks! The only thing I could gather is that we might have our ROC too low for the P-38 and P-51. Since that is not the current question, I didn't look too deeply into that. As far as the maneuver rating goes, I couldn't tell much. A subject matter expert might.

BTW, regarding that chart (from the site) that I linked to above, it's pretty amazing how some of the altitude/max speed 'curves' are actually zig-zags!

[witpqs]

ORIGINAL: el cid again
The question is: what is the special case effect? Add a point or two to the
maneuverability? Or multiply it times 1.5? Or something else?

Sid,

Here's my best guess. Considering my lack of expertise in this area, somebody with real knowledge please shoot it down if it's all wet.

I hesitate to say 'multiply it times 1.5' because some plane you find might bust the range limit (up to 30) that you've set. Furthermore, the true modification might be non-linear. Maybe a plane with a higher intrinsic value gets less added-value from the power aerilons?

I suggest adding '7' to the P-38J and L models, making their maneuverability values 21 and 22 respectively.

That is about a 1.5 multiple, but I would be cautious about using that as a general rule. I think 'black magic' is appropriate here.